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Soliman L, De Souza A, Srinivasan P, Danish M, Bertone P, El-Deiry WS, Carneiro BA. The Role of BCL-2 Proteins in the Development of Castration-resistant Prostate Cancer and Emerging Therapeutic Strategies. Am J Clin Oncol 2021; 44:374-382. [PMID: 34014842 DOI: 10.1097/coc.0000000000000829] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The development of androgen resistance in advanced prostate cancer remains a challenging clinical problem. Because androgen deprivation therapy constitutes the backbone of first-line treatments for metastatic prostate cancer, the phenotypic switch from an androgen-dependent to an androgen-independent growth state limits the treatment options for these patients. This critical change from an androgen-dependent to an androgen-independent growth state can be regulated by the B-cell lymphoma gene 2 (BCL-2) family of apoptotic proteins. While the roles of BCL-2 protein family members in the carcinogenesis of prostate cancer have been well-studied, emerging data also delineates their modulation of disease progression to castration-resistant prostate cancer (CRPC). Over the past 2 decades, investigators have sought to describe the mechanisms that underpin this development at the molecular level, yet no recent literature has consolidated these findings in a dedicated review. As new classes of BCL-2 family inhibitors are finding indications for other cancer types, it is time to evaluate how such agents might find stable footing for the treatment of CRPC. Several trials to date have investigated BCL-2 inhibitors as therapeutic agents for CRPC. These therapies include selective BCL-2 inhibitors, pan-BCL-2 inhibitors, and novel inhibitors of MCL-1 and BCL-XL. This review details the research regarding the role of BCL-2 family members in the pathogenesis of prostate cancer and contextualizes these findings within the contemporary landscape of prostate cancer treatment.
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Affiliation(s)
- Luke Soliman
- Warren Alpert Medical School of Brown University
| | - Andre De Souza
- Warren Alpert Medical School of Brown University
- Division of Hematology/Oncology, Lifespan Cancer Institute
- Cancer Center at Brown University
| | | | - Matthew Danish
- Warren Alpert Medical School of Brown University
- Division of Hematology/Oncology, Lifespan Cancer Institute
| | - Paul Bertone
- Warren Alpert Medical School of Brown University
- Division of Hematology/Oncology, Lifespan Cancer Institute
- Cancer Center at Brown University
| | - Wafik S El-Deiry
- Warren Alpert Medical School of Brown University
- Division of Hematology/Oncology, Lifespan Cancer Institute
- Cancer Center at Brown University
- Department of Pathology and Laboratory Medicine, The Warren Alpert Medical School, Brown University, Providence, RI
| | - Benedito A Carneiro
- Warren Alpert Medical School of Brown University
- Division of Hematology/Oncology, Lifespan Cancer Institute
- Cancer Center at Brown University
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2
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Liang Y, Jeganathan S, Marastoni S, Sharp A, Figueiredo I, Marcellus R, Mawson A, Shalev Z, Pesic A, Sweet J, Guo H, Uehling D, Gurel B, Neeb A, He HH, Montgomery B, Koritzinsky M, Oakes S, de Bono JS, Gleave M, Zoubeidi A, Wouters BG, Joshua AM. Emergence of Enzalutamide Resistance in Prostate Cancer is Associated with BCL-2 and IKKB Dependencies. Clin Cancer Res 2021; 27:2340-2351. [PMID: 33542074 DOI: 10.1158/1078-0432.ccr-20-3260] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/23/2020] [Accepted: 02/02/2021] [Indexed: 11/16/2022]
Abstract
PURPOSE Although enzalutamide (ENZ) has been widely used to treat de novo or castration-resistant metastatic prostate cancer, resistance develops and disease progression is ultimately inevitable. There are currently no approved targeted drugs to specifically delay or overcome ENZ resistance. EXPERIMENTAL DESIGN We selected several ENZ-resistant cell lines that replicated clinical characteristics of the majority of patients with ENZ-resistant disease. A high-throughput pharmacologic screen was utilized to identify compounds with greater cytotoxic effect for ENZ-resistant cell lines, compared with parental ENZ-sensitive cells. We validated the potential hits in vitro and in vivo, and used knockdown and overexpression assays to study the dependencies in ENZ-resistant prostate cancer. RESULTS ABT199 (BCL-2 inhibitor) and IMD0354 (IKKB inhibitor) were identified as potent and selective inhibitors of cell viability in ENZ-resistant cell lines in vitro and in vivo which were further validated using loss-of-function assays of BCL-2 and IKKB. Notably, we observed that overexpression of BCL-2 and IKKB in ENZ-sensitive cell lines was sufficient for the emergence of ENZ resistance. In addition, we confirmed that BCL-2 or IKKB inhibitors suppressed the development of ENZ resistance in xenografts. However, validation of both BCL-2 and IKKB in matched castration-sensitive/resistant clinical samples showed that, concurrent with the development of ENZ/abiraterone resistance in patients, only the protein levels of IKKB were increased. CONCLUSIONS Our findings identify BCL-2 and IKKB dependencies in clinically relevant ENZ-resistant prostate cancer cells in vitro and in vivo, but indicate that IKKB upregulation appears to have greater relevance to the progression of human castrate-resistant prostate cancer.
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Affiliation(s)
- Yi Liang
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Sujeeve Jeganathan
- Quality Control Analytical Excellence, Sanofi Pasteur, Toronto, Ontario, Canada
| | - Stefano Marastoni
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Adam Sharp
- Royal Marsden Hospital, Sutton, Surrey, United Kingdom.,The Institute of Cancer Research, London, United Kingdom
| | | | - Richard Marcellus
- Drug Discovery Program, Ontario Institute for Cancer Research, Toronto, Ontario, Canada
| | - Amanda Mawson
- Garvan Institute of Medical Research, Sydney, Australia
| | - Zvi Shalev
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Aleksandra Pesic
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Joan Sweet
- Department of Laboratory Medicine and Pathobiology, University Health Network, Toronto, Ontario, Canada
| | - Haiyang Guo
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - David Uehling
- Drug Discovery Program, Ontario Institute for Cancer Research, Toronto, Ontario, Canada
| | - Bora Gurel
- The Institute of Cancer Research, London, United Kingdom
| | - Antje Neeb
- The Institute of Cancer Research, London, United Kingdom
| | - Housheng Hansen He
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Bruce Montgomery
- Department of Medicine and Oncology, University of Washington, Seattle Cancer Care Alliance, Seattle, Washington
| | - Marianne Koritzinsky
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.,Department of Radiation Oncology, Department of Medical Biophysics, Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Samantha Oakes
- Garvan Institute of Medical Research, Sydney, Australia.,Faculty of Medicine, UNSW Sydney, Australia
| | - Johann S de Bono
- Royal Marsden Hospital, Sutton, Surrey, United Kingdom.,The Institute of Cancer Research, London, United Kingdom
| | - Martin Gleave
- Department of Urologic Sciences and Vancouver Prostate Centre, University of British Columbia, Vancouver, Canada
| | - Amina Zoubeidi
- Department of Urologic Sciences and Vancouver Prostate Centre, University of British Columbia, Vancouver, Canada
| | - Bradly G Wouters
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.,Department of Radiation Oncology, Department of Medical Biophysics, University of Toronto, Ontario Institute for Cancer Research, Toronto, Ontario, Canada
| | - Anthony M Joshua
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada. .,Garvan Institute of Medical Research, Sydney, Australia.,Faculty of Medicine, UNSW Sydney, Australia.,Department of Medical Oncology, Kinghorn Cancer Centre, St Vincent's Hospital, Sydney, Australia
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3
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Review: Mathematical Modeling of Prostate Cancer and Clinical Application. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10082721] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We review and synthesize key findings and limitations of mathematical models for prostate cancer, both from theoretical work and data-validated approaches, especially concerning clinical applications. Our focus is on models of prostate cancer dynamics under treatment, particularly with a view toward optimizing hormone-based treatment schedules and estimating the onset of treatment resistance under various assumptions. Population models suggest that intermittent or adaptive therapy is more beneficial to delay cancer relapse as compared to the standard continuous therapy if treatment resistance comes at a competitive cost for cancer cells. Another consensus among existing work is that the standard biomarker for cancer growth, prostate-specific antigen, may not always correlate well with cancer progression. Instead, its doubling rate appears to be a better indicator of tumor growth. Much of the existing work utilizes simple ordinary differential equations due to difficulty in collecting spatial data and due to the early success of using prostate-specific antigen in mathematical modeling. However, a shift toward more complex and realistic models is taking place, which leaves many of the theoretical and mathematical questions unexplored. Furthermore, as adaptive therapy displays better potential than existing treatment protocols, an increasing number of studies incorporate this treatment into modeling efforts. Although existing modeling work has explored and yielded useful insights on the treatment of prostate cancer, the road to clinical application is still elusive. Among the pertinent issues needed to be addressed to bridge the gap from modeling work to clinical application are (1) real-time data validation and model identification, (2) sensitivity analysis and uncertainty quantification for model prediction, and (3) optimal treatment/schedule while considering drug properties, interactions, and toxicity. To address these issues, we suggest in-depth studies on various aspects of the parameters in dynamical models such as the evolution of parameters over time. We hope this review will assist future attempts at studying prostate cancer.
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Davies AH, Wang Y, Zoubeidi A. Patient-derived xenografts: A platform for accelerating translational research in prostate cancer. Mol Cell Endocrinol 2018; 462:17-24. [PMID: 28315377 DOI: 10.1016/j.mce.2017.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 03/01/2017] [Accepted: 03/13/2017] [Indexed: 11/19/2022]
Abstract
Recently, there has been renewed interest in the development and characterization of patient-derived tumour xenograft (PDX) models. Numerous PDX models have been established for prostate cancer and, importantly, retain the principal molecular, genetic, and histological characteristics of the donor tumour. As such, these models provide significant improvements over standard cell line xenograft models for biological studies, preclinical drug development, and personalized medicine strategies. This review summarizes the current state of the art in this field, illustrating the opportunities and limitations of PDX models in translational prostate cancer research.
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Affiliation(s)
- Alastair H Davies
- Vancouver Prostate Centre, Vancouver, BC, Canada; Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Yuzhuo Wang
- Vancouver Prostate Centre, Vancouver, BC, Canada; Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Amina Zoubeidi
- Vancouver Prostate Centre, Vancouver, BC, Canada; Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
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Martin-Sanchez D, Fontecha-Barriuso M, Sanchez-Niño MD, Ramos AM, Cabello R, Gonzalez-Enguita C, Linkermann A, Sanz AB, Ortiz A. Cell death-based approaches in treatment of the urinary tract-associated diseases: a fight for survival in the killing fields. Cell Death Dis 2018; 9:118. [PMID: 29371637 PMCID: PMC5833412 DOI: 10.1038/s41419-017-0043-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/26/2017] [Accepted: 10/05/2017] [Indexed: 02/06/2023]
Abstract
Urinary tract-associated diseases comprise a complex set of disorders with a variety of etiologic agents and therapeutic approaches and a huge global burden of disease, estimated at around 1 million deaths per year. These diseases include cancer (mainly prostate, renal, and bladder), urinary tract infections, and urolithiasis. Cell death plays a key role in the pathogenesis and therapy of these conditions. During urinary tract infections, invading bacteria may either promote or prevent host cell death by interfering with cell death pathways. This has been studied in detail for uropathogenic E. coli (UPEC). Inhibition of host cell death may allow intracellular persistence of live bacteria, while promoting host cell death causes tissue damage and releases the microbes. Both crystals and urinary tract obstruction lead to tubular cell death and kidney injury. Among the pathomechanisms, apoptosis, necroptosis, and autophagy represent key processes. With respect to malignant disorders, traditional therapeutic efforts have focused on directly promoting cancer cell death. This may exploit tumor-specific characteristics, such as targeting Vascular Endothelial Growth Factor (VEGF) signaling and mammalian Target of Rapamycin (mTOR) activity in renal cancer and inducing survival factor deprivation by targeting androgen signaling in prostate cancer. An area of intense research is the use of immune checkpoint inhibitors, aiming at unleashing the full potential of immune cells to kill cancer cells. In the future, this may be combined with additional approaches exploiting intrinsic sensitivities to specific modes of cell death such as necroptosis and ferroptosis. Here, we review the contribution of diverse cell death mechanisms to the pathogenesis of urinary tract-associated diseases as well as the potential for novel therapeutic approaches based on an improved molecular understanding of these mechanisms.
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Affiliation(s)
- Diego Martin-Sanchez
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Miguel Fontecha-Barriuso
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Maria Dolores Sanchez-Niño
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Adrian M Ramos
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
- IRSIN, Madrid, Spain
- REDINREN, Madrid, Spain
| | - Ramiro Cabello
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain
| | | | - Andreas Linkermann
- Department of Internal Medicine III, Division of Nephrology, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Ana Belén Sanz
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain.
- IRSIN, Madrid, Spain.
- REDINREN, Madrid, Spain.
| | - Alberto Ortiz
- Research Institute-Fundacion Jimenez Diaz, Autonoma University, Madrid, Spain.
- IRSIN, Madrid, Spain.
- REDINREN, Madrid, Spain.
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6
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Hoang DT, Iczkowski KA, Kilari D, See W, Nevalainen MT. Androgen receptor-dependent and -independent mechanisms driving prostate cancer progression: Opportunities for therapeutic targeting from multiple angles. Oncotarget 2017; 8:3724-3745. [PMID: 27741508 PMCID: PMC5356914 DOI: 10.18632/oncotarget.12554] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/29/2016] [Indexed: 12/25/2022] Open
Abstract
Despite aggressive treatment for localized cancer, prostate cancer (PC) remains a leading cause of cancer-related death for American men due to a subset of patients progressing to lethal and incurable metastatic castrate-resistant prostate cancer (CRPC). Organ-confined PC is treated by surgery or radiation with or without androgen deprivation therapy (ADT), while options for locally advanced and disseminated PC include radiation combined with ADT, or systemic treatments including chemotherapy. Progression to CRPC results from failure of ADT, which targets the androgen receptor (AR) signaling axis and inhibits AR-driven proliferation and survival pathways. The exact mechanisms underlying the transition from androgen-dependent PC to CRPC remain incompletely understood. Reactivation of AR has been shown to occur in CRPC despite depletion of circulating androgens by ADT. At the same time, the presence of AR-negative cell populations in CRPC has also been identified. While AR signaling has been proposed as the primary driver of CRPC, AR-independent signaling pathways may represent additional mechanisms underlying CRPC progression. Identification of new therapeutic strategies to target both AR-positive and AR-negative PC cell populations and, thereby, AR-driven as well as non-AR-driven PC cell growth and survival mechanisms would provide a two-pronged approach to eliminate CRPC cells with potential for synthetic lethality. In this review, we provide an overview of AR-dependent and AR-independent molecular mechanisms which drive CRPC, with special emphasis on the role of the Jak2-Stat5a/b signaling pathway in promoting castrate-resistant growth of PC through both AR-dependent and AR-independent mechanisms.
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Affiliation(s)
- David T Hoang
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kenneth A Iczkowski
- Department of Pathology, Medical College of Wisconsin Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Deepak Kilari
- Department of Medicine, Medical College of Wisconsin Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - William See
- Department of Urology, Medical College of Wisconsin Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Marja T Nevalainen
- Department of Pathology, Medical College of Wisconsin Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Pharmacology/Toxicology, Medical College of Wisconsin Cancer Center, Medical College of Wisconsin, Milwaukee, WI, USA
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7
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Zhu W, Shao Y, Yang M, Jia M, Peng Y. Asparaginyl endopeptidase promotes proliferation and invasiveness of prostate cancer cells via PI3K/AKT signaling pathway. Gene 2016; 594:176-182. [PMID: 27590439 DOI: 10.1016/j.gene.2016.08.049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 08/01/2016] [Accepted: 08/29/2016] [Indexed: 12/27/2022]
Abstract
Recurrence and metastasis are the major lethal causes of prostate cancer. It is urgent to find out the mechanisms and key factors governing prostate cancer progression and metastasis for developing new therapeutic strategies. Asparaginyl endopeptidase (AEP) overexpression has been found in a number of solid tumors. In prostate cancer, AEP has also been shown to exhibit a vesicular staining pattern and significantly associated with advanced tumor stage, high Gleason score, perineural invasion, and larger tumor. Here, we found that AEP was differentially expressed in prostate cancer cells with higher expression in 22RV1 cells and lower expression in PC-3 cells. AEP knockdown in 22RV1 cells significantly inhibited cell proliferation and invasion abilities while overexpression of AEP in PC-3 cells prompted cell proliferation and invasion abilities. Meanwhile, AEP knockdown upregulated cell apoptosis and vice versa. Further, we firstly identified that AEP promotes activation of the PI3K-AKT signaling pathway in prostate cancer cells. Taken together, our results suggest that AEP may be an attractive target for prostate cancer therapy.
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Affiliation(s)
- Wenjing Zhu
- Department of Urology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yiqun Shao
- Department of Urology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Ming Yang
- Department of Urology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Moran Jia
- Department of Urology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yu Peng
- Department of Urology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
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8
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De Maeseneer DJ, Van Praet C, Lumen N, Rottey S. Battling resistance mechanisms in antihormonal prostate cancer treatment: Novel agents and combinations. Urol Oncol 2015; 33:310-21. [DOI: 10.1016/j.urolonc.2015.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 01/11/2015] [Accepted: 01/12/2015] [Indexed: 10/24/2022]
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9
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Lauer RC, Friend SC, Rietz C, Pasqualini R, Arap W. Drug design strategies for the treatment of prostate cancer. Expert Opin Drug Discov 2014; 10:81-90. [PMID: 25366417 DOI: 10.1517/17460441.2015.978855] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
INTRODUCTION While metastatic prostate cancer remains an incurable tumor, remarkable progress has been made with novel drug design strategies for this incurable disease. Several new agents, including hormonal analogues, cytotoxic chemotherapy drugs, radionuclides and innovative targeted therapies, have recently been approved by the FDA for use in advanced and/or metastatic castrate-resistant prostate cancer. Furthermore, a growing number of new diagnostic or predictive genetic tests have also been incorporated into the management of this disease. Immunotherapy-based approaches have shown promise and have led to drug approvals. Other experimental approaches such as vascular targeting are in early translational clinical trials. AREAS COVERED Herein, the authors outline select state-of-the-art approaches in the field. They also discuss the current challenges and future opportunities in the medical care of prostate cancer patients. EXPERT OPINION An inherent challenge in the treatment of prostate cancer is to determine which patients need immediate aggressive treatment versus active surveillance. For patients needing aggressive treatment, integrating the sequence of therapeutic interventions, to provide the most benefit, remains a challenge that clinicians face. Recently, several genetic tests have been approved, facilitating early treatment decisions. Innovative targeted therapies are moving towards clinical applications, providing treatment options for tumors previously considered refractory to androgen ablation treatment.
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Affiliation(s)
- Richard C Lauer
- University of New Mexico Cancer Center, Division of Hematology/Oncology, UNM CC Molecular Medicine , MSC07 4025, Albuquerque, 87131 , USA
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Muniyan S, Chou YW, Ingersoll MA, Devine A, Morris M, Odero-Marah VA, Khan SA, Chaney WG, Bu XR, Lin MF. Antiproliferative activity of novel imidazopyridine derivatives on castration-resistant human prostate cancer cells. Cancer Lett 2014; 353:59-67. [PMID: 25050738 PMCID: PMC4150829 DOI: 10.1016/j.canlet.2014.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 06/28/2014] [Accepted: 07/03/2014] [Indexed: 02/07/2023]
Abstract
Metastatic prostate cancer (mPCa) relapses after a short period of androgen deprivation therapy and becomes the castration-resistant prostate cancer (CR PCa); to which the treatment is limited. Hence, it is imperative to identify novel therapeutic agents towards this patient population. In the present study, antiproliferative activities of novel imidazopyridines were compared. Among three derivatives, PHE, AMD and AMN, examined, AMD showed the highest inhibitory activity on LNCaP C-81 cell proliferation, following dose- and time-dependent manner. Additionally, AMD exhibited significant antiproliferative effect against a panel of PCa cells, but not normal prostate epithelial cells. Further, when compared to AMD, its derivative DME showed higher inhibitory activities on PCa cell proliferation, clonogenic potential and in vitro tumorigenicity. The inhibitory activity was apparently in part due to the induction of apoptosis. Mechanistic studies indicate that AMD and DME treatments inhibited both AR and PI3K/Akt signaling. The results suggest that better understanding of inhibitory mechanisms of AMD and DME could help design novel therapeutic agents for improving the treatment of CR PCa.
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Affiliation(s)
- Sakthivel Muniyan
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Yu-Wei Chou
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA; Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan, ROC
| | - Matthew A Ingersoll
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Alexus Devine
- Department of Chemistry, Clark Atlanta University, Atlanta, GA, USA
| | - Marisha Morris
- Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Valerie A Odero-Marah
- Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA; Center for Cancer Research and Therapeutic Development, Clark Atlanta University, Atlanta, GA, USA
| | - Shafiq A Khan
- Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA; Center for Cancer Research and Therapeutic Development, Clark Atlanta University, Atlanta, GA, USA
| | - William G Chaney
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Xiu R Bu
- Department of Chemistry, Clark Atlanta University, Atlanta, GA, USA; Laboratory for Electro-Optical Materials & NASA Center for High Performance Polymers and Composites, Clark Atlanta University, Atlanta, GA, USA
| | - Ming-Fong Lin
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA; Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA; Department of Surgery/Urology, University of Nebraska Medical Center, Omaha, NE, USA; School of Pharmacy, Kaohsiung Medical University, Kaohsiung 807, Taiwan, ROC.
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11
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Adaptation or selection--mechanisms of castration-resistant prostate cancer. Nat Rev Urol 2012; 10:90-8. [PMID: 23247694 DOI: 10.1038/nrurol.2012.237] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Men with advanced prostate cancer are typically treated with hormonal therapy, which leads to tumour shrinkage. However, tumours relapse and develop into the lethal form of the disease, termed castration-resistant prostate cancer (CRPC). Two distinct, but not mutually exclusive, models have been proposed in the literature to describe the onset of CRPC: adaptation and selection. Although some studies indicate that tumour cells acquire new alterations that enable them to survive in the castrated state (adaptation), other research points to the outgrowth of rare, pre-existing cells capable of surviving hormonal therapy (selection). Targeting the cells that survive hormonal therapy--by either adaptation or selection--is necessary to prevent the development of CRPC. Current research is focused on not only understanding the cellular mechanisms of CRPC, but also defining critical pathways that can be targeted with combinatorial therapies in castration-resistant cancer cells.
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12
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Abstract
Although androgen-deprivation therapy is the standard therapy for advanced and metastatic prostate cancer, this treatment is only palliative. Prostate cancer recurs then grows despite low circulating testicular androgens, using several mechanisms that remain dependent on androgen-receptor signaling in most cases. This article reviews the diversity of mechanisms used for growth by castration-recurrent prostate cancer.
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13
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Song JH, Kraft AS. Pim kinase inhibitors sensitize prostate cancer cells to apoptosis triggered by Bcl-2 family inhibitor ABT-737. Cancer Res 2012; 72:294-303. [PMID: 22080570 PMCID: PMC3251634 DOI: 10.1158/0008-5472.can-11-3240] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pim serine/threonine kinases contribute to prostate tumorigenesis and therapeutic resistance, yet Pim kinase inhibitors seem to have only limited effects on prostate cancer cell survival. Because overexpression of Bcl-2 family members are implicated in chemotherapeutic resistance in prostate cancer, we investigated the cooperative effects of Pim kinase inhibition with ABT-737, a small molecule antagonist of Bcl-2 family members. Strikingly, the addition of ABT-737 to Pim inhibitors triggered a robust apoptosis of prostate cancer cells in vitro and in vivo. Pim inhibitors decreased levels of the Bcl-2 family member Mcl-1, both by blocking 5'-cap dependent translation and decreasing protein half life. In addition, Pim inhibition transcriptionally increased levels of the BH3 protein Noxa by activating the unfolded protein response (UPR), lead to eIF-2α phosphorylation and increased expression of CHOP. Increased levels of Noxa also inactivated the remaining levels of Mcl-1 protein activity. Notably, these specific protein changes were essential to the apoptotic process because ABT-737 did not inhibit Mcl-1 protein activity and Mcl-1 overexpression blocked the apoptotic activity of ABT-737. Our results therefore suggest that this combination treatment could be developed as a potential therapy for human prostate cancer where overexpression of Pim kinases and antiapoptotic Bcl-2 family members drives tumor cell resistance to current anticancer therapies.
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Affiliation(s)
- Jin H. Song
- Departments of Biochemistry and Molecular Biology, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425
- Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425
| | - Andrew S. Kraft
- Department of Medicine, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425
- Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425
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14
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Saraon P, Jarvi K, Diamandis EP. Molecular alterations during progression of prostate cancer to androgen independence. Clin Chem 2011; 57:1366-75. [PMID: 21956922 DOI: 10.1373/clinchem.2011.165977] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Prostate cancer is the most commonly diagnosed cancer among men in North America and is a leading cause of death. Standard treatments include androgen deprivation therapy, which leads to improved clinical outcomes. However, over time, most tumors become androgen independent and no longer respond to hormonal therapies. Several mechanisms have been implicated in the progression of prostate cancer to androgen independence. CONTENT Most tumors that have become androgen independent still rely on androgen receptor (AR) signaling. Mechanisms that enhance AR signaling in androgen-depleted conditions include: AR gene amplification, AR mutations, changes in the balance of AR cofactors, increases in steroidogenic precursors, and activation via "outlaw" pathways. Along with AR signaling, various other AR-independent "bypass" pathways have been shown to operate aberrantly during androgen independence. Changes in the epigenetic signatures and microRNA concentrations have also been implicated in the development of androgen-independent prostate cancer. SUMMARY Understanding of the molecular mechanisms that lead to the development of androgen-independent prostate cancer will allow for improved therapeutic strategies that target key pathways and molecules that are essential for these cells to survive.
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Affiliation(s)
- Punit Saraon
- Samuel Lunenfeld Research Institute and Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada
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15
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Putzke AP, Ventura AP, Bailey AM, Akture C, Opoku-Ansah J, Celiktaş M, Hwang MS, Darling DS, Coleman IM, Nelson PS, Nguyen HM, Corey E, Tewari M, Morrissey C, Vessella RL, Knudsen BS. Metastatic progression of prostate cancer and e-cadherin regulation by zeb1 and SRC family kinases. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:400-10. [PMID: 21703419 DOI: 10.1016/j.ajpath.2011.03.028] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 02/06/2011] [Accepted: 03/08/2011] [Indexed: 12/12/2022]
Abstract
Expression of E-cadherin is used to monitor the epithelial phenotype, and its loss is suggestive of epithelial-mesenchymal transition (EMT). EMT triggers tumor metastasis. Exit from EMT is marked by increased E-cadherin expression and is considered necessary for tumor growth at sites of metastasis; however, the mechanisms associated with exit from EMT are poorly understood. Herein are analyzed 185 prostate cancer metastases, with significantly higher E-cadherin expression in bone than in lymph node and soft tissue metastases. To determine the molecular mechanisms of regulation of E-cadherin expression, three stable isogenic cell lines from DU145 were derived that differ in structure, migration, and colony formation on soft agar and Matrigel. When injected into mouse tibia, the epithelial subline grows most aggressively, whereas the mesenchymal subline does not grow. In cultured cells, ZEB1 and Src family kinases decrease E-cadherin expression. In contrast, in tibial xenografts, E-cadherin RNA levels increase eight- to 10-fold despite persistent ZEB1 expression, and in all ZEB1-positive metastases (10 of 120), ZEB1 and E-cadherin proteins were co-expressed. These data suggest that transcriptional regulation of E-cadherin differs in cultured cells versus xenografts, which more faithfully reflect E-cadherin regulation in cancers in human beings. Furthermore, the aggressive nature of xenografts positive for E-cadherin and the frequency of metastases positive for E-cadherin suggest that high E-cadherin expression in metastatic prostate cancer is associated with aggressive tumor growth.
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Affiliation(s)
- Aaron P Putzke
- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington; Department of Biology, Hope College, Holland, Michigan
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16
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Song R, Harris LD, Pettaway CA. Downmodulation of Bcl-2 sensitizes metastatic LNCaP-LN3 cells to undergo apoptosis via the intrinsic pathway. Prostate 2010; 70:571-83. [PMID: 19938012 DOI: 10.1002/pros.21091] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND We explored the mechanisms of apoptosis after Bcl-2 protein downmodulation in metastatic LNCaP-LN3 cells (LN3). METHODS LNCaP, LNCaP-Pro5 (Pro5) and LN3 cells were cultured in 5% charcoal-stripped serum (CSS) or in R1881 (synthetic androgen) and bicalutamide (synthetic anti-androgen) and growth inhibition was assessed. Expression levels of androgen receptor (AR) and Bcl-2 were determined. LN3 cells were transfected with small interfering RNA Bcl-2 (siRNA Bcl-2) or control siRNA oligonucleotides. Rates of apoptosis and proliferation were obtained. Cytochrome c localization in treated and control cells was assessed +/- cyclosporine A (CsA). Caspases 9, 3, and poly (ADP-ribose) polymerase cleavage (PARP) were measured upon downmodulation of Bcl-2; and cell growth inhibition in vitro after Bcl-2 modulation combined with docetaxel chemotherapy was determined. RESULTS LN3 cells maintained growth under castrate conditions in vitro. AR protein amplification did not explain castrate-resistant LN3 cell growth. Bcl-2 protein levels in LN3 cells were significantly higher than in Pro5 cells, and were effectively downmodulated by siRNA Bcl-2. Subsequently increased apoptosis and decreased proliferation mediated by cytochrome c was noted and this was reversed by CsA. siRNA Bcl-2-transfected LN3 cells exhibited elevated levels of caspases 9, 3, and PARP cleavage. Exposure of LN3 cells to docetaxel led to increased apoptosis, and simultaneous downmodulation of Bcl-2 substantially enhanced this effect. CONCLUSIONS Downmodulation of Bcl-2 in metastatic castrate-resistant LNCaP-LN3 cells led to apoptosis via a cytochrome c-dependent pathway that was enhanced with docetaxel treatment.
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Affiliation(s)
- Renduo Song
- Department of Urology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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17
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Graff JR, Konicek BW, Lynch RL, Dumstorf CA, Dowless MS, McNulty AM, Parsons SH, Brail LH, Colligan BM, Koop JW, Hurst BM, Deddens JA, Neubauer BL, Stancato LF, Carter HW, Douglass LE, Carter JH. eIF4E activation is commonly elevated in advanced human prostate cancers and significantly related to reduced patient survival. Cancer Res 2009; 69:3866-73. [PMID: 19383915 DOI: 10.1158/0008-5472.can-08-3472] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Elevated eukaryotic translation initiation factor 4E (eIF4E) function induces malignancy in experimental models by selectively enhancing translation of key malignancy-related mRNAs (c-myc and BCL-2). eIF4E activation may reflect increased eIF4E expression or phosphorylation of its inhibitory binding proteins (4E-BP). By immunohistochemical analyses of 148 tissues from 89 prostate cancer patients, we now show that both eIF4E expression and 4E-BP1 phosphorylation (p4E-BP1) are increased significantly, particularly in advanced prostate cancer versus benign prostatic hyperplasia tissues. Further, increased eIF4E and p4E-BP1 levels are significantly related to reduced patient survival, whereas uniform 4E-BP1 expression is significantly related to better patient survival. Both immunohistochemistry and Western blotting reveal that elevated eIF4E and p4E-BP1 are evident in the same prostate cancer tissues. In two distinct prostate cancer cell models, the progression to androgen independence also involves increased eIF4E activation. In these prostate cancer cells, reducing eIF4E expression with an eIF4E-specific antisense oligonucleotide currently in phase I clinical trials robustly induces apoptosis, regardless of cell cycle phase, and reduces expression of the eIF4E-regulated proteins BCL-2 and c-myc. Collectively, these data implicate eIF4E activation in prostate cancer and suggest that targeting eIF4E may be attractive for prostate cancer therapy.
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Affiliation(s)
- Jeremy R Graff
- Lilly Research Labs, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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Shimada T, Aihara K. A nonlinear model with competition between prostate tumor cells and its application to intermittent androgen suppression therapy of prostate cancer. Math Biosci 2008; 214:134-9. [DOI: 10.1016/j.mbs.2008.03.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 03/03/2008] [Accepted: 03/04/2008] [Indexed: 10/22/2022]
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Maitland NJ, Collins AT. Prostate cancer stem cells: a new target for therapy. J Clin Oncol 2008; 26:2862-70. [PMID: 18539965 DOI: 10.1200/jco.2007.15.1472] [Citation(s) in RCA: 229] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The existence of prostate cancer stem cells offers a theoretical explanation for many of the enduring uncertainties surrounding the etiology and treatment of the most commonly diagnosed tumor in US males. The study of cancer stem cells in prostate, as in other complex tissues, is critically dependent on the availability of pure cell populations, a situation complicated by the heterogeneity of prostate tumors. However, selection of cells with a CD133(+)/alpha 2 beta 1 integrin/ CD44(+) phenotype enriches for a tumor-initiating population from human prostate cancers. Among the most pressing needs is for enduring therapy in patients who have experienced failure of hormonal treatments. Because the putative cancer stem cell does not express androgen receptor, it is likely to be immune from most androgen-based therapies, and an inherent genetic instability would enable the tumor to develop the new variants present in hormone-refractory disease. Prostate cancer stem cells have a unique gene expression signature that can also be related to Gleason grade and patient outcome. The scarcity of cancer stem cells in a prostate tumor will probably limit their usefulness in cancer diagnosis and prognosis. However, the emergence of new stem-cell therapeutic targets not only will require new assays for efficacy (because of their relatively quiescent nature), but also holds real promise of more lasting treatments to augment those currently directed against the remaining tumor cells, which comprise 99.9% of tumor mass, but paradoxically have a poor tumor-initiating capacity.
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Affiliation(s)
- Norman J Maitland
- YCR Cancer Research Unit, Department of Biology, University of York, Heslinton, York, YO10 5YW, United Kingdom.
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20
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Robust expression of Prominin-2 all along the adult male reproductive system and urinary bladder. Histochem Cell Biol 2008; 130:749-59. [DOI: 10.1007/s00418-008-0445-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2008] [Indexed: 01/21/2023]
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21
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Cai Y, Lee YF, Li G, Liu S, Bao BY, Huang J, Hsu CL, Chang C. A new prostate cancer therapeutic approach: combination of androgen ablation with COX-2 inhibitor. Int J Cancer 2008; 123:195-201. [PMID: 18386814 DOI: 10.1002/ijc.23481] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Prostate cancer is initially responsive to hormonal therapy, but cancers inevitably progress in an androgen-independent fashion with virtually all tumors evolving into more aggressive androgen refractory disease. Immunohistological comparisons of cyclooxygenase 2 (COX-2) expressions in 3 pairs of prostate cancer patients before and after the combined androgen blockade (CAB) therapy show elevated COX-2 expressions. This observation from clinical specimens is further supported by in vitro laboratory data using human prostate cancer cells in which the antiandrogen hydroxyflutamide (HF) induced COX-2 expression, and androgen suppressed COX-2 expression. By applying knockdown and overexpression strategies to modulate AR expression in prostate cancer cells, we confirmed that androgen/AR signal suppressed, and HF induced COX-2 expression at both protein and mRNA levels. COX-2 promoter reporter assay indicated that the suppression of COX-2 by androgen/AR is at the transcriptional level via modulation of NF-kappaB signals. Treatment of LNCaP and LAPC4 cells with 1 microM HF in the presence of 1 nM DHT, which mimics the CAB therapy condition, promotes cell growth, and this growth induction can be suppressed via adding the COX-2 specific inhibitor, NS398. This suggests that HF promoted prostate cancer cell growth is COX-2 dependent and this HF-COX-2 activation pathway can account for one reason of CAB therapy failure. Together, these findings provide a possible explanation how CAB with antiandrogen HF therapy might fail and provide a potential new therapeutic approach to battle prostate cancer via combination of CAB therapy with COX-2 inhibitor(s).
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Affiliation(s)
- Yi Cai
- George H. Whipple Laboratory for Cancer Research, Department of Pathology, University of Rochester Medical Center, Rochester, NY 14642, USA
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Abstract
Stromal-epithelial interactions mediated by paracrine signaling mechanisms dictate prostate development and progression of prostate cancer. The regulatory role of androgens in both the prostate stromal and epithelial compartments set the prostate apart from many other organs and tissues with regard to gene targeting. The identification of androgen-dependent prostate epithelial promoters has allowed successful gene targeting to the prostate epithelial compartment. Currently, there are no transgenic mouse models available to specifically alter gene expression within the prostate stromal compartment. As a primary metastatic site for prostate cancer is bone, the functional dissection of the bone stromal compartment is important for understanding stromal-epithelial interactions associated with metastatic tumor growth. Use of currently available methodologies for the expression or deletion of gene expression in recent research studies has advanced our understanding of the stroma. However, the complexity of stromal heterogeneity within the prostate remains a challenge to obtaining compartment or cell-lineage-specific in vivo models necessary for furthering our understanding of prostatic developmental, benign, tumorigenic, and metastatic growth.
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Affiliation(s)
- Roger S Jackson
- Department of Urologic Surgery, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232-2765, USA
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23
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Gomez LA, de Las Pozas A, Reiner T, Burnstein K, Perez-Stable C. Increased expression of cyclin B1 sensitizes prostate cancer cells to apoptosis induced by chemotherapy. Mol Cancer Ther 2007; 6:1534-43. [PMID: 17513602 DOI: 10.1158/1535-7163.mct-06-0727] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chemotherapeutic drugs ideally should take advantage of the differences between transformed and normal cells and induce apoptosis only in cancer cells. One such difference may be the overexpression of cyclin B1 protein in cancer cells, which is required for the proper progression through mitosis. Previously, we showed that treatment of human prostate cancer cells with 2-methoxyestradiol (2-ME) or docetaxel results in an accumulation of cyclin B1 protein and an increase in cyclin B1 kinase activity, followed by induction of apoptotic cell death. Inhibition of cyclin B1 kinase lowers apoptosis induced by 2-ME and docetaxel. In this study, we established a positive correlation between cyclin B1 protein and apoptosis induced by chemotherapy in prostate cancer cells. There is minimal cyclin B1 and induction of apoptosis by chemotherapy in nontransformed cells. LNCaP and PC-3 prostate cancer cells stably overexpressing cyclin B1 are more sensitive to apoptosis induced by chemotherapy. LNCaP cells expressing cyclin B1 small interfering RNA to lower cyclin B1 protein or dominant negative cyclin-dependent kinase 1 to inhibit cyclin B1 kinase show a decrease in apoptosis. Increased sensitivity to apoptosis by overexpression of cyclin B1 may be due to lower Bcl-2, higher p53, and decreased neuroendocrine differentiation. We suggest that a cancer-specific mechanism whereby 2-ME and docetaxel may exert anti-prostate cancer activity is the deregulated activation of cyclin B1 kinase, leading to the induction of apoptotic cell death. Our results also suggest that higher levels of cyclin B1 in prostate cancer cells may be a good prognostic marker for chemotherapy.
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Affiliation(s)
- Lourdes A Gomez
- Geriatric Research, Education, and Clinical Center and Research Service, VA Medical Center, University of Miami Miller School of Medicine, 1201 Northwest 16 Street, Miami, FL 33125, USA
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24
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Patrikainen L, Porvari K, Kurkela R, Hirvikoski P, Soini Y, Vihko P. Expression profiling of PC-3 cell line variants and comparison of MIC-1 transcript levels in benign and malignant prostate. Eur J Clin Invest 2007; 37:126-33. [PMID: 17217378 DOI: 10.1111/j.1365-2362.2007.01763.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The mechanisms behind prostate cancer progression are largely unknown, but macrophage inhibitory cytokine 1 (MIC-1) has been suggested to be involved in tumour dissemination in vivo due to its reductive effect on cell adhesion. MATERIALS AND METHODS We used two PC-3 prostate cancer epithelial cell line variants as tools to screen for gene expression differences during prostate cancer progression by cDNA microarray analysis. Selected genes were further analysed by Northern blot analysis using mRNA isolated from prostatic cell lines and tissues. MIC-1 expression was studied by in situ hybridization in archival patient specimens containing benign and malignant prostatic tissue. RESULTS Gene expression of human collagen type VI, basement membrane heparan sulphate proteoglycan, integrin alpha 1, and fibronectin I were remarkably decreased in suspension-adapted PC-3 (saPC-3) cells, indicating a gene expression profile of reduced cell adhesion. Asparagine synthetase, serine protease 1, stanniocalcin homologue, NAD-dependent methylene tetrahydrate dehydrogenase cyclohydrolase (NMDMC), fortilin, and MIC-1 were overexpressed in saPC-3 cells. In prostate, the MIC-1 gene was mainly expressed in cancer tissue. However, MIC-1 transcripts were detected in benign tissue areas, especially in specimens containing prostate cancer with Gleason sum scores of 5-8. A significant inverse correlation (Spearman's rho correlation coefficient -0.928**) was observed between the ratio of cancerous to benign MIC-1 expression levels and Gleason scores. CONCLUSIONS Differential expression of the MIC-1 gene occurs during prostate cancer progression. The transcript level of the MIC-1 gene in histologically benign tissue seems to approach that in paired cancer tissue concomitant with an increasing Gleason score.
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Affiliation(s)
- L Patrikainen
- WHO Collaborating Centre for Research on Reproductive Health University of Oulu, Finland
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25
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Su Z, Hong H, Perkins R, Shao X, Cai W, Tong W. Consensus analysis of multiple classifiers using non-repetitive variables: Diagnostic application to microarray gene expression data. Comput Biol Chem 2007; 31:48-56. [PMID: 17303535 DOI: 10.1016/j.compbiolchem.2007.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Revised: 12/05/2006] [Accepted: 01/02/2007] [Indexed: 10/23/2022]
Abstract
Class prediction based on DNA microarray data has been emerged as one of the most important application of bioinformatics for diagnostics/prognostics. Robust classifiers are needed that use most biologically relevant genes embedded in the data. A consensus approach that combines multiple classifiers has attributes that mitigate this difficulty compared to a single classifier. A new classification method named as consensus analysis of multiple classifiers using non-repetitive variables (CAMCUN) was proposed for the analysis of hyper-dimensional gene expression data. The CAMCUN method combined multiple classifiers, each of which was built from distinct, non-repeated genes that were selected for effectiveness in class differentiation. Thus, the CAMCUN utilized most biologically relevant genes in the final classifier. The CAMCUN algorithm was demonstrated to give consistently more accurate predictions for two well-known datasets for prostate cancer and leukemia. Importantly, the CAMCUN algorithm employed an integrated 10-fold cross-validation and randomization test to assess the degree of confidence of the predictions for unknown samples.
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Affiliation(s)
- Zhenqiang Su
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
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26
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Nelson EC, Cambio AJ, Yang JC, Ok JH, Lara PN, Evans CP. Clinical implications of neuroendocrine differentiation in prostate cancer. Prostate Cancer Prostatic Dis 2006; 10:6-14. [PMID: 17075603 DOI: 10.1038/sj.pcan.4500922] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The cellular signaling pathways of the prostate play a central role in the induction, maintenance, and progression of prostate cancer (CaP). Neuroendocrine (NE) cells demonstrate attributes that suggest they are an integral part of these signaling cascades. We summarize what is known regarding NE cells in CaP focusing on NE cellular transdifferentiation. This significant event in CaP progression appears to be accelerated by androgen deprivation (AD) treatment. We examine biochemical pathways that may impact NE differentiation in a chronological manner focusing on AD therapy (ADT) as a central event in inducing androgen-independent CaP. Our analysis is limited to the common adenocarcinoma pattern of CaP and excludes small-cell and carcinoid prostatic variants. In conclusion, we speculate on the future of treatment and research in this area.
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Affiliation(s)
- E C Nelson
- Department of Urology, Davis Medical Center, University of California at Davis, Sacramento, CA 95817, USA
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27
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Pang ST, Weng WH, Flores-Morales A, Johansson B, Pourian MR, Nilsson P, Pousette A, Larsson C, Norstedt G. Cytogenetic and expression profiles associated with transformation to androgen-resistant prostate cancer. Prostate 2006; 66:157-72. [PMID: 16173030 DOI: 10.1002/pros.20328] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The mechanisms underlying the progression of prostate cancer to androgen-resistant cancer are still not fully understood. Here, we studied the genetic events associated with this transformation. METHODS The androgen sensitive prostate cancer cells line LNCaP-FGC and its androgen resistant subline LNCaP-r were investigated using SKY, CGH, and cDNA microarray. RESULTS Karyotypically, several additional chromosomal aberrations were seen in LNCaP-r as compared to the parental line. CGH also revealed unique net chromosomal alterations in LNCaP-r compared to LNCaP-FGC, including gain of 2p13-23, 2q21-32, and 13q and loss of 6p22-pter. cDNA microarray analysis identified several genes involved in DNA methylation, such as DNMT2, DNMT3a, and methyl-CpG binding domain protein 2 and 4 that were higher expressed in LNCaP-r. Interestingly, androgen responsiveness of LNCaP-r was restored after treated with DNA methyltransferase inhibitor. CONCLUSIONS Our findings may serve as a basis for molecular dissection of the mechanisms involved in development of androgen resistant prostate cancer.
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Affiliation(s)
- See-Tong Pang
- Department of Surgery, Division of Urology, Chang Gung Memorial Hospital, Kwei-Shan, Tao Yuan, Taiwan.
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28
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Fina F, Muracciole X, Rocchi P, Nanni-Métellus I, Delfino C, Daniel L, Dussert C, Ouafik L'H, Martin PM. Molecular profile of androgen-independent prostate cancer xenograft LuCaP 23.1. J Steroid Biochem Mol Biol 2005; 96:355-65. [PMID: 16043352 DOI: 10.1016/j.jsbmb.2005.04.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
After castration or therapeutic hormone deprivation, most cancer of the prostate (CaP) cells develop androgen-independent (AI) growth. In this work, we studied the effect of androgen depletion (castration) on the growth of experimental model LuCaP 23.1 xenograft. A total of 101 nude mice were implanted and analysed for their growth profile before experimental period 1 (11 weeks) and after castration experimental period 2 (15 weeks). For specific periods, tumors were harvested and assessed for molecular marker expression specific for CaP. Taking into account tumor dynamic growth, prior to castration we found 37 fast growing (FG) tumors (948.9+/-76.9 mm3) and 63 slow growing (SG) tumors (229.6+/-18.4 mm3). Real-time quantitative RT-PCR showed that in comparison to SGs, FGs contained elevated expression of epidermal growth factor receptor type 1 (HER1), urokinase plasminogen activator (uPA), thymidine phosphorylase (TP) and thymidilate synthase (TS) mRNAs expression and low levels of 5alpha-reductase 2 (5alpha-R2) mRNA. After castration all FG tumors progressed rapidly (by 5 weeks) to AI growth (FG-P). In SG castrated tumors, 66% of tumors showed retarded progression (by 12 weeks) to AI (SG-P), whereas 34% responded to castration (SG-R). Molecular analysis demonstrated distinct molecular profiles integrating different pathways associated with AI progression. The progressive tumors FG-P, and some tumors of SG-P subgroup, presented significantly high levels of HER1, epidermal growth factor receptor type 2 (HER2), TS, uPA, TP, tumor necrosis factor superfamily member 6 (FAS) and peptidylglycine alpha-amidating mono-oxygenase (PAM) mRNA all of which correlated with androgen receptor (AR) mRNA. The second subgroup of SG-P tumors showed a high expression of the anti-apoptotic gene Bcl-2. A third subgroup of SG-P tumors showed significant expression of hypoxia-related genes such as adrenomedullin (AM) after castration. LuCaP 23.1 xenograft represent a useful dynamic model to study pre-clinically new therapeutic molecules and evaluate non-randomized therapeutics protocols combining different target inhibition specific to each AI pathways.
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Affiliation(s)
- F Fina
- Université de la Méditerranée, Aix-Marseille II, Laboratoire de Transfert d'Oncologie Biologique, Assistance Publique--Hôpitaux de Marseille (AP-HM), Faculté de Médecine Secteur nord, Bd Pierre Dramard, 13916 Marseille Cedex, France
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Khatib AM, Bassi D, Siegfried G, Klein-Szanto AJP, Ouafik L. Endo/exo-proteolysis in neoplastic progression and metastasis. J Mol Med (Berl) 2005; 83:856-64. [PMID: 16133424 DOI: 10.1007/s00109-005-0692-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Accepted: 04/22/2005] [Indexed: 10/25/2022]
Abstract
Biological control of individual cells, organs, and organisms is achieved through interplay of a host of specific interactions that involve various peptidic molecules as modulators or effectors. In tumor cells, these processes may result in uncontrolled growth as a consequence of autocrine and/or paracrine actions. In recent years, growing evidence has accumulated for the important role of proprotein convertases (PCs) and peptide alpha-amidation enzymes in these processes. The widespread belief that these enzymes are involved in the major features of tumor progression, namely, invasiveness and metastasis, has taken place because of their capacity to process and activate many protein precursors involved in the neoplastic progression and metastasis. This includes degrading extracellular matrix proteases, growth promoting factors, and adhesion molecules. Usually, when the processing of these precursor proteins is achieved by one or more of the known PC family members within the general motif (K/R)-(X)n-(K/R) downward arrow, where n=0, 2, 4, or 6, and X, any amino acid except Cys, the accomplishment of the maturation of these molecules is attained by various posttranslational modifications, including the carboxy-terminal alpha-amidation. This review article summarizes recent findings on the role of these enzymatic systems in multiple cellular functions that impact on the invasive/metastatic potential of cancer cells and highlight the potential use of their inhibitors in the treatment of multiple cancers.
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30
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Jackson TL. A mathematical investigation of the multiple pathways to recurrent prostate cancer: comparison with experimental data. Neoplasia 2005; 6:697-704. [PMID: 15720795 PMCID: PMC1531673 DOI: 10.1593/neo.04259] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Considerable research is aimed at determining the mechanisms by which hormone-refractory prostate cancer develops. In an effort to assist in the understanding of recurrent prostate cancer and the cellular processes that mediate this disease, a mathematical model is presented that describes both the pretreatment growth and the posttherapy relapse of human prostate cancer xenografts. Our goal is to evaluate the interplay between the multiple mechanisms that have been postulated as causes of androgen-independent relapse. Simulations of the model show that molecular events that render the androgen receptor irrelevant to disease progression, such as upregulation of BCL2, can result in relapse after androgen deprivation therapy. However, decreased apoptosis of androgen-independent cells alone overestimates the effects of hormone therapy when compared to experimental data. When decreased apoptosis is combined with continual androgen receptor activation, the posttherapy growth dynamics are in excellent correlation with experimental observations of the growth of LuCaP xenografts. Furthermore, the mathematical model predicts that upregulation of the androgen receptor, together with its increased activation, is alone sufficient to result in the androgen-independent growth of LNCaP xenografts. Recent experimental studies that suggest that the posttherapy increase in and continual activation of the androgen receptor are common and crucial features of recurrent prostate cancer provide validation of the model predictions. This approach provides a framework for using mathematical techniques to study novel therapeutic strategies aimed at controlling this disease.
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Affiliation(s)
- Trachette L Jackson
- Department of Mathematics, 525 E. University, University of Michigan, Ann Arbor, MI 48109-1109, USA.
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Liu AY, Roudier MP, True LD. Heterogeneity in primary and metastatic prostate cancer as defined by cell surface CD profile. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 165:1543-56. [PMID: 15509525 PMCID: PMC1618667 DOI: 10.1016/s0002-9440(10)63412-8] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/07/2004] [Indexed: 10/18/2022]
Abstract
Cluster designation (CD) antigens are cell surface markers that can be used to identify constituent cell populations of an organ. We have previously determined the CD phenotype of normal prostate parenchymal cells and are now extending this analysis to prostate cancer. Since expression of CD antigens is associated with cellular differentiation, cancer cells may differ from their normal counterpart in their CD profile. Compared with luminal secretory cells, prostate adenocarcinoma cells are frequently negative for CD10 and CD13, express increased levels of the cell activation molecule CD24, and decreased levels of the apoptosis-associated multifunctional enzyme CD38. Expression of CD57, CD63, CD75s, CD107a, CD107b, CD164, and CD166 by cancer cells is similar to that of secretory cells. Prostate basal epithelial cells do not express the CD antigens characteristic of prostate secretory cells; and the basal cell CD markers, CD29, CD44, CD49b, CD49f, CD104, and nerve growth factor receptor (NGFR) are not expressed by cancer cells. The preferential expression of secretory cell-associated CD markers by prostate cancer cells suggests a closer lineage relationship between cancer cells and secretory cells than basal cells. Although the above cancer CD phenotype was the most frequently seen, some prostate cancers contained populations of CD10- and/or CD13-positive cells, and CD57-negative cells. Furthermore, the cancer phenotype of tumor metastasis is different. Despite its low frequency in primary tumors, CD10 is expressed by virtually all of the nodal metastases of prostate cancer. In addition, stromal fibromuscular cells associated with primary prostate cancer differ from stromal cells in benign prostate tissue by an increased level of expression of the cell activation molecule, CD90. In summary, our data show that the CD marker expression profile of prostate cancer cells most closely resembles that of secretory prostate epithelial cells and that some prostate cancers consist of heterogeneous cell populations as distinguished by CD-marker expression profiles.
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Affiliation(s)
- Alvin Y Liu
- Department of Urology, Box 356510, University of Washington, Seattle, WA 98195, USA.
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Rocchi P, Muracciole X, Fina F, Mulholland DJ, Karsenty G, Palmari J, Ouafik L, Bladou F, Martin PM. Molecular analysis integrating different pathways associated with androgen-independent progression in LuCaP 23.1 xenograft. Oncogene 2004; 23:9111-9. [PMID: 15489889 DOI: 10.1038/sj.onc.1208154] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
After therapeutic hormone deprivation, most prostate cancer (PrCa) cells develop androgen-independent (AI) growth. PrCa is highly heterogeneous and multifocal, suggesting that several molecular processes or pathways may be contributing to AI. The human LuCaP 23.1 xenograft model retains clinical hallmarks of PrCa, including heterogeneous growth, PSA production, androgen-responsiveness and progression to AI. In this work, we studied the effect of androgen depletion (castration) on the growth of LuCaP 23.1 xenografts. A total of 100 nude mice were implanted and analysed for their growth profiles before and after castration. By 11 and 15 weeks, tumours were harvested and assessed for molecular marker expression specific for PrCa. Prior to castration we found 37 fast growing (FG) tumours (948.9+/-76.9 mm(3)) and 63 slow growing (SG) tumours (229.6+/-18.4 mm(3)), a previously undescribed result for this PrCa model. Quantitative RT-PCR showed that in comparison to SGs, FGs contained high HER1, uPA and thymidilate synthetase (TS) expression with low levels of 5alpha-reductase 2 mRNA. All FG tumours progressed rapidly to AI growth 5 weeks after castration (FG-P). In SG castrated tumours, 66% of tumours (SG-P) showed retarded progression (by 12 weeks) to AI, whereas 34% responded to castration (SG-R). Molecular analysis permitted us to define distinct molecular profiles integrating different pathways associated with AI progression. FG-P, and a subgroup of SG-P tumours, presented significantly high levels of peptidylglycine alpha-amidating monooxygenase (PAM), HER1, HER2, TS, and uPA mRNA, all of which correlated with AR expression. The second subgroup of SG-P tumours showed overexpression of the antiapoptotic gene Bcl-2. A third subgroup of SG-P tumours showed significant expression of hypoxia-related gene (adrenomedullin) after castration. This work permitted to define distinct molecular profiles related to different AI growth in the LuCaP 23.1 xenograft.
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Affiliation(s)
- Palma Rocchi
- Laboratoire de Cancérologie Expérimentale EMI 0359/Laboratoire de Transfert d'Oncologie Biologique, Assistance Publique-Hôpitaux de Marseille IFR Jean Roche, Faculté de Médecine de Marseille, France.
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Angelucci A, Festuccia C, Gravina GL, Muzi P, Bonghi L, Vicentini C, Bologna M. Osteopontin enhances the cell proliferation induced by the epidermal growth factor in human prostate cancer cells. Prostate 2004; 59:157-66. [PMID: 15042616 DOI: 10.1002/pros.20008] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Susceptibility to extracellular matrix and growth factors has been demonstrated to play a critical role in the development of prostate cancer (PCa) metastases. The aim of this study was to elucidate some mechanisms by which stroma controls tumor progression. METHODS In our study we tested the growth ability of the LNCaP human prostatic cell line in steroid-free culture conditions in response to osteopontin (OPN), a non-collageneous matrix protein, localized in large amounts in the bone. RESULTS In the LNCaP cell model, OPN stimulates cell proliferation in serum-free medium and colony growth at high dilution but this effect is visible only in presence of epidermal growth factor (EGF). Proliferation induced by OPN is accompanied by a sustained activation of EGF receptor (EGFR) whose phosphorylation is detectable up to 12 hr after treatment in association with EGF. The colocalization of integrin beta1, a ligand of OPN, and of EGFR on the cellular membrane, suggests that the association of these cell surface receptors may be the principal mechanism involved in the long-term activation of the EGFR. CONCLUSIONS Our data describe a new possible mechanism involved in the establishment of bone metastases which may also account for the formation of androgen-independent cellular clones, frequently responsible of the clinical progression of PCa.
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Affiliation(s)
- Adriano Angelucci
- Department of Experimental Medicine, University of L'Aquila, Medical School, Coppito-2, L'Aquila, Italy.
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Peng W, Verbitsky A, Bao Y, Sawicki J. Regulated expression of diphtheria toxin in prostate cancer cells. Mol Ther 2002; 6:537-45. [PMID: 12377196 DOI: 10.1006/mthe.2002.0694] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Despite their known potential for effectively killing cells, the therapeutic use of plant and bacterial toxins for the treatment of cancer has been slow to enter the clinical setting. This has been due in large part to the lack of gene regulatory elements that control expression of highly toxic genes in a sufficiently tight manner, such that the toxins are only expressed in specific target cells. "Leaky" promoters result in unwanted and harmful cell death. In this study, we tested a novel gene therapy strategy aimed at expressing diphtheria toxin (DT-A) in androgen-independent prostate cancer cells that express the protein BCL2. This strategy relies on both transcriptional regulation and inducibly regulated DNA recombination mediated by the site-directed Flp recombinase to control expression of the toxin. Adenoviruses are used to introduce the genetic elements required for this approach into cultured cells and xenografts. Administration of 4-hydroxytamoxifen, resulting in recombination and expression of the toxin, effectively kills the cancer cells. Our results suggest that following androgen ablation therapy for the treatment of prostate cancer, use of a regulated recombination system to target expression of DT-A to androgen-independent cancer cells would be an effective way to arrest the development of recurrent tumors.
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Affiliation(s)
- Weidan Peng
- Lankenau Institute for Medical Research, Wynnewood, Pennsylvania 19096, USA.
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36
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Abstract
BACKGROUND Loss of contact with the extracellular matrix (ECM) triggers a specialized form of apoptosis known as "anoikis" in normal epithelial cells. Dependence on adhesion to ECM is often lost in transformed cells, and the degree of anchorage independence may vary in non-metastatic and metastatic cancer cells. BCL-2 oncoprotein overexpression correlates with the progression and metastases of prostate cancer. Materials and Methods We studied anoikis in suspension cultures of PC-3 and LNCaP prostate carcinoma cells selected for enhanced metastatic potential in vivo and in PC-3 and LNCaP cells stably transfected with BCL-2. Apoptosis-associated DNA fragmentation was measured by agarose gel electrophoresis and propidium iodide staining and flow cytometry. Expression of BCL-2 family polypeptides was determined by immunoblotting. RESULTS Non-metastatic PC-3P cells were significantly more sensitive to anoikis than the metastatic PC-3 variants (PC-3M, PC-3M-PRO-4, and PC-3M-LN-4), but anoikis resistance did not correlate with metastatic potential in LNCaP-derived cell lines. Expression of BCL-2 was higher in metastatic PC-3 and LNCaP subclones compared to isogenic non-metastatic cells, but these levels were not affected by anoikis. Enforced overexpression of BCL-2 did not protect either PC-3P or LNCaP-PRO-5 cells from anoikis, even though it rendered them resistant to thapsigargin and inhibited cytochrome c release. Strikingly, cells that died of anoikis maintained their pretreatment levels of BCL-2, whereas the cells that survived anoikis expressed much lower levels of the protein. CONCLUSIONS Sensitivity to anoikis is regulated by BCL-2 independent mechanisms in LNCaP and PC-3 prostate cancer cells.
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Affiliation(s)
- Victor M Bondar
- Department of Cancer Biology, University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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Jongsma J, Oomen MH, Noordzij MA, Van Weerden WM, Martens GJM, van der Kwast TH, Schröder FH, van Steenbrugge GJ. Different profiles of neuroendocrine cell differentiation evolve in the PC-310 human prostate cancer model during long-term androgen deprivation. Prostate 2002; 50:203-15. [PMID: 11870798 DOI: 10.1002/pros.10049] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Neuroendocrine (NE) cells are androgen-independent cells and secrete growth-modulating peptide hormones via a regulated secretory pathway (RSP). We studied NE differentiation after long-term androgen withdrawal in the androgen-dependent human prostate cancer xenograft PC-310. METHODS Tumor-bearing nude mice were killed at 0, 2, 5, 7, 14, 21, 47, 84, and 154 days after castration. The half-life of the PC-310 tumor was 10 days, with a stable residual tumor volume of 30--40% after 21 days and longer periods of androgen deprivation. RESULTS Proliferative activity and prostate-specific antigen serum levels decreased to zero after castration, whereas cell-cycle arrest was manifested by increased p27(kip1) expression. A temporary downregulation of androgen receptor (AR) expression was noted after androgen deprivation. The expression of chromogranin A, secretogranin III, and secretogranin V (7B2) increased 5 days after castration and later. Subsequently, pro-hormone convertase 1 and peptidyl alpha--amidating monooxygenase as well as vascular endothelial growth factor were expressed from 7 days after castration on. Finally, such growth factors as gastrin-releasing peptide and serotonin were expressed in a small part of the NE cells 21 days after castration, but strong expression was induced late during androgen deprivation, that is, 84 and 154 days after castration, respectively. CONCLUSIONS Androgen deprivation of the NE-differentiated PC-310 model induced the formation of NE-differentiated AR(minus sign) and non-NE AR(+) tumor residues. The NE-differentiated cells actively produced growth factors via an RSP that may lead to hormone-refractory disease. The dormant non-NE AR(+) tumor cells were shown to remain androgen sensitive even after long-term androgen deprivation. In the PC-310 xenograft, time-dependent NE differentiation and subsequent maturation were induced after androgen depletion. The androgen-dependent PC-310 xenograft model constitutes an excellent model for studying the role of NE cells in the progression of clinical prostate cancer.
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Affiliation(s)
- Johan Jongsma
- Department of Experimental Urology, Josephine Nefkens Institute, Erasmus University, Rotterdam, Netherlands.
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Abstract
The normal prostate and early-stage prostate cancers depend on androgens for growth and survival, and androgen ablation therapy causes them to regress. Cancers that are not cured by surgery eventually become androgen independent, rendering anti-androgen therapy ineffective. But how does androgen independence arise? We predict that understanding the pathways that lead to the development of androgen-independent prostate cancer will pave the way to effective therapies for these, at present, untreatable cancers.
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Affiliation(s)
- B J Feldman
- Department of Medicine, Stanford University School of Medicine, California 94305-5103, USA.
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Honn KV, Aref A, Chen YQ, Cher ML, Crissman JD, Forman JD, Gao X, Grignon D, Hussain M, Porter AT, Pontes EJ, Powell I, Redman B, Sakr W, Severson R, Tang DG, Wood DP. Prostate Cancer - Old Problems and New Approaches. (Part II. Diagnostic and Prognostic Markers, Pathology and Biological Aspects). Pathol Oncol Res 2001; 2:191-211. [PMID: 11173606 DOI: 10.1007/bf02903527] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Diagnostic and prognostic markers for prostatic cancer (PCa) include conventional protein markers (e.g., PAP, PSA, PSMA, PIP, OA-519, Ki-67, PCNA, TF, collagenase, and TIMP 1), angiogenesis indicator (e.g., factor VIII), neuroendocrine differentiation status, adhesion molecules (E-cadherin, integrin), bone matrix degrading products (e.g., ICPT), as well as molecular markers (e.g., PSA, PSMA, p53, 12-LOX, and MSI). Currently, only PSA is used clinically for early diagnosis and monitoring of PCa. The histological differential diagnosis of prostatic adenocarcinoma includes normal tissues such as Cowper's gland, paraganglion tissue and seminal vesicle or ejaculatory duct as well as pathological conditions such as atypical adenomatous hyperplasia, atrophy, basal cell hyperplasia and sclerosing adenosis. A common PCa is characterized by a remarkable heterogeneity in terms of its differentiation, microscopic growth patterns and biological aggressiveness. Most PCa are multifocal with signi ficant variations in tumor grade between anatomically separated tumor foci. The Gleason grading system which recognizes five major grades defined by patterns of neoplastic growth has gained almost uniform acceptance. In predicting the biologic behavior of PCa clinical and pathological stages are used as the major prognostic indicators. Among the cell proliferation and death regulators androgens are critical survival factors for normal prostate epithelial cells as well as for the androgen-dependent human prostatic cancer cells. The androgen ablation has been shown to increase the apoptotic index in prostatic cancer patients and castration also promotes apoptotic death of human prostate carcinoma grown in mice. The progression of PCa, similarly to other malignancies, is a multistep process, accompanied by genetic and epigenetic changes, involving phenomenons as adhesion, invasion and angiogenesis (without prostate specific features).
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Affiliation(s)
- Kenneth V Honn
- Wayne State University, Cancer Biology Division, Department of Radiation Oncology, Detroit, USA
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Abstract
Apoptosis is a cell suicide program characterized by distinct morphological (cell shrinkage, membrane blebbing, pyknosis, chromatin margination, denser cytoplasmic images) and biochemical (e.g., DNA fragmentation into distinct ladders; degradation of apoptotic markers such as PARP and nuclear lamins) features. It is involved in multiple physiological processes examplified by involution of mammary tissues, embryonic development, homeostatic maintenance of tissues and organs, and maturation of the immune system, as well as in many pathological conditions represented by neurologic degeneration (Alzeimer's disease), autoimmune and inflammatory diseases, etiology of atherosclerosis, AIDS, and oncogenesis and tumor progression. Numerous molecular entities have been shown to regulate the apoptotic process. This review provides a concise summary of the recent data on the role of oncogenes/tumor suppressor genes, cytokines and growth factors/growth factor receptors, intracellular signal transducers, cell cycle regulators, reactive oxygen species or other free radicals, extracellular matrix regulators/cell adhesion molecules, and specific endonucleases and cytoplasmic proteases (the ICE family proteins) in regulating cell survival and apoptosis. Elucidation of the molecular mechanisms regulating apoptosis bears tremendous impact on enhancing our understanding of many diseases inflicting the human beings and undoubtedly brings us hope for the cure of these diseases.
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Affiliation(s)
- Dean G Tang
- Wayne State University, Department of Radiation Oncology, Detroit, USA
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41
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Abstract
BACKGROUND An increased understanding of the biology of prostate carcinoma has led to the clinical evaluation of mechanism-based and targeted therapies. Modulating the immune system has been pursued through the use of both active and passive immunity as well as the ex vivo genetic manipulation of effector cells. A variety of gene therapies has been proposed not only to replace defective genes but to localize activation of prodrugs. Angiogenesis and tumor invasion also have been targeted, as have cell cycling and signal transduction. Strategies promoting apoptosis and augmenting differentiation are also under study. METHODS This study is a review of current clinical strategies using biologic, immunologic, and genetic approaches for the treatment of prostate carcinoma. RESULTS The clinical development of therapy targeting differentiation, apoptosis, cell signaling, angiogenesis, metastasis, immune surveillance, and others are in various stages of clinical development. A disease states model is used to discuss treatment groups, outcome measures, and other trial design elements in relation to specific therapeutic strategies. CONCLUSIONS Development of novel agents requires consideration of where in the natural history of the disease they should be applied. In addition, understanding the genetic and molecular alterations that occur as the disease progresses from a localized to a metastatic state, and from androgen dependence to independence, is necessary. Clinical trial design will require consideration of cytostatic and cytotoxic effects, the status of pathways not directly targeted, and potentially unexpected influences on prostate specific antigen expression by these agents.
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Affiliation(s)
- M J Morris
- Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
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Abstract
BACKGROUND Our understanding of the mechanisms of (progressive) growth of prostatic cancer has been largely obtained through the study of experimental animal models. To be able to validate new concepts, representative model systems of human origin that mimic the clinical process of the disease in patients are essential. Unfortunately, the limited number of human prostate tumor models has considerably hampered research. METHODS Various research groups have put much effort in the development of human prostate tumor xenograft models, and large numbers of clinical prostate tumors were heterotransplanted in immune-deficient host animals. This huge effort has resulted in a number of tumor lines which are reviewed here. RESULTS Up to now, approximately 25 xenograft models of human prostate cancer have been established and reported in the literature. The available xenografts seem to represent the various stages of clinical prostate cancer, such as early progression and transition from androgen-dependent to androgen-independent growth. In addition, recent efforts are concentrating on the establishment of in vitro cell lines from these xenografts as well as on the development of (bone) metastatic variants. CONCLUSIONS Xenograft models are important for elucidating regulatory pathways of tumor growth and progression and are indispensible for testing of new treatment modalities.
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Affiliation(s)
- W M van Weerden
- Department of Experimental Urology, Josephine Nefkens Institute, Erasmus University Rotterdam, The Netherlands.
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Jongsma J, Oomen MH, Noordzij MA, Romijn JC, van Der Kwast TH, Schröder FH, van Steenbrugge GJ. Androgen-independent growth is induced by neuropeptides in human prostate cancer cell lines. Prostate 2000; 42:34-44. [PMID: 10579797 DOI: 10.1002/(sici)1097-0045(20000101)42:1<34::aid-pros5>3.0.co;2-2] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Androgen-independent growth leads to progressive prostate cancer after androgen-ablation therapy. This may be caused by altered specificity of the androgen receptor (AR), by ligand-independent stimulation of the AR, or by paracrine growth modulation by neuropeptides secreted by neuroendocrine (NE) cells. METHODS We established and characterized the androgen-independent FGC-DCC from the androgen-dependent LNCaP fast growing colony (FGC) cell line. The androgen-independent DU-145, FGC-DCC, and PC-3, and the androgen-dependent LNCaP and PC-346C cell lines were used to study growth modulation of gastrin-releasing peptide (GRP), calcitonin (CT), serotonin (5-HT), and vasoactive intestinal peptide (VIP) by (3)H-thymidine incorporation. Specificity of the growth-modulating effects was tested with the anti-GRP monoclonal antibody 2A11 and induction of cAMP by neuropeptides. RESULTS Androgen-independent growth stimulation by neuropeptides was shown in DU-145 and PC-346C. 2A11 inhibited GRP-induced (3)H-thymidine incorporation in DU-145 and PC-346C and inhibited proliferation of the FGC-DCC and PC-3 cell lines. With some exceptions, cAMP induction paralleled growth stimulation. Dideoxyadenosine (DDA) inhibited the GRP-induced growth effect in DU-145 and PC-346C, whereas oxadiazoloquinoxaline-1-one (ODQ) had no effect on (3)H-thymidine incorporation. None of the neuropeptides stimulated growth of LNCaP, FGC-DCC, or PC-3. CONCLUSIONS GRP-induced growth of DU-145 and PC-346C was specific and cAMP-mediated. Androgen-independent growth of FGC-DCC cells was mainly due to an induction of Bcl-2 expression and possibly through the activation of an autocrine and NE-like pathway, as has been shown also for the PC-3 cell line. Growth induction of non-NE cells by neuropeptides could be a possible role for NE cells in clinical prostate cancer.
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Affiliation(s)
- J Jongsma
- Department of Experimental Urology, Erasmus University, Rotterdam, The Netherlands.
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Jongsma J, Oomen MH, Noordzij MA, Van Weerden WM, Martens GJ, van der Kwast TH, Schröder FH, van Steenbrugge GJ. Kinetics of neuroendocrine differentiation in an androgen-dependent human prostate xenograft model. THE AMERICAN JOURNAL OF PATHOLOGY 1999; 154:543-51. [PMID: 10027412 PMCID: PMC1850014 DOI: 10.1016/s0002-9440(10)65300-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/26/1998] [Indexed: 10/18/2022]
Abstract
It was previously shown in the PC-295 xenograft that the number of chromogranin A (CgA)-positive neuroendocrine (NE) cells increased after androgen withdrawal. NE cells did not proliferate and differentiated from G0-phase-arrested cells. Here we further characterized NE differentiation, androgen receptor status, and apoptosis-associated Bcl-2 expression in the PC-295 model after androgen withdrawal to assess the origin of NE cells. PC-295 tumor volumes decreased by 50% in 4 days. Intraperitoneal bromodeoxyuridine (BrdU) incorporation and MIB-1 labeling decreased to 0%, and the apoptosis was maximal at day 4. Androgen receptor expression and prostate-specific antigen (PSA) serum levels decreased rapidly within 2 days. The number of NE cells increased 6-fold at day 4 and 30-fold at day 7. Five and ten percent of the CgA-positive cells were BrdU positive after continuous BrdU labeling for 2 and 4 days, respectively. However, no MIB-1 expression was observed in CgA-positive cells. NE cells expressed the regulated secretory pathway marker secretogranin III but were negative for androgen receptor and Bcl-2. Bcl-2 expression did increase in the non-NE tumor cells. In conclusion, androgen withdrawal leads to a rapid PC-295 tumor regression and a proliferation-independent induction of NE differentiation. The strictly androgen-independent NE cells that were still present after 21 days differentiated mainly from G0-phase-arrested cells.
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Affiliation(s)
- J Jongsma
- Department of Urology, Erasmus University, Rotterdam, The Netherlands.
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Liu AY, True LD, LaTray L, Nelson PS, Ellis WJ, Vessella RL, Lange PH, Hood L, van den Engh G. Cell-cell interaction in prostate gene regulation and cytodifferentiation. Proc Natl Acad Sci U S A 1997; 94:10705-10. [PMID: 9380699 PMCID: PMC23453 DOI: 10.1073/pnas.94.20.10705] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
To examine the role of intercellular interaction on cell differentiation and gene expression in human prostate, we separated the two major epithelial cell populations and studied them in isolation and in combination with stromal cells. The epithelial cells were separated by flow cytometry using antibodies against differentially expressed cell-surface markers CD44 and CD57. Basal epithelial cells express CD44, and luminal epithelial cells express CD57. The CD57+ luminal cells are the terminally differentiated secretory cells of the gland that synthesize prostate-specific antigen (PSA). Expression of PSA is regulated by androgen, and PSA mRNA is one of the abundant messages in these cells. We show that PSA expression by the CD57+ cells is abolished after prostate tissue is dispersed by collagenase into single cells. Expression is restored when CD57+ cells are reconstituted with stromal cells. The CD44+ basal cells possess characteristics of stem cells and are the candidate progenitors of luminal cells. Differentiation, as reflected by PSA production, can be detected when CD44+ cells are cocultured with stromal cells. Our studies show that cell-cell interaction plays an important role in prostatic cytodifferentiation and the maintenance of the differentiated state.
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Affiliation(s)
- A Y Liu
- Department of Urology, University of Washington, Seattle, WA 98195, USA.
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Abstract
BACKGROUND Prostate cancer is the most commonly diagnosed neoplasm and the second leading cause of male death in this country. Multiple genetic and epigenetic factors have been implicated in the oncogenesis and progression of prostate cancer. However, the molecular mechanisms underlying the disease remain largely unknown. The major difficulty in the clinical management of prostate cancer stems from the reality that reliable and accurate diagnostic/prognostic biomarkers are not available and that effective treatment regimens for hormone-resistant prostate cancers are yet to be developed. METHODS The present review, through extensive literature research, summarizes the most recently accumulated experimental and clinical data on the relationship between apoptosis and prostate cancer. We analyze the possibility of inducing prostate cancer cell apoptosis by: 1) androgen ablation by castration or biochemical antagonists: 2) chemotherapeutic drugs or natural/synthetic chemicals; 3) manipulation of apoptosis-related oncoproteins; and 4) modulation of intracellular signal transducers. RESULTS 1) Prostate cancer, like most other solid tumors, represents a very heterogeneous entity. Most prostate cancers, at the time of clinical diagnosis, present themselves as mixtures of androgen-dependent and androgen-independent cells. 2) Most prostate cancers respond initially to androgen ablation since the population of androgen-dependent cells undergoes rapid apoptosis upon androgen withdrawal. However, androgen ablation rarely cures patients, most of whom will experience recurrence due to takeover of the tumor mass by androgen-independent tumor cells as well as the emergence of apoptosis-resistant clones as a result of further genetic alterations such as bcl-2 amplification. 3) On the other hand, although androgen-independent prostate cancer cells do not undergo apoptosis upon androgen blocking, they do maintain the appropriate molecular machinery of apoptosis. Therefore, certain conventional chemotherapy drugs can eliminate androgen-independent cancer cells by inducing apoptosis. 4) However, most drugs used in chemotherapy induce apoptosis or mediate cytotoxicity only in proliferating cancer cells. Human prostate cancer cells demonstrate very slow growth kinetics. Thus, novel chemical/natural products need be identified to eradicate those nonproliferating cancer cells. In this regard, the angiogenesis inhibitor, linomide, and a plant extract, beta-lapachone, demonstrate very promising apoptosis-inducing effects on prostate cancer cells in a proliferation-independent manner. 5) An alternative way to modulate the apoptotic response is by interfering with the expression levels of essential regulatory molecule of apoptosis. Bcl-2 and p53 represent two prime targets for such manipulations. 6) Finally, modulation of signal transduction pathways (e.g., intracellular Ca2+ levels, PKC activity) involved in apoptosis may also induce and/or enhance the apoptotic response of prostate cancer cells. CONCLUSIONS Modulation of apoptotic response represents a novel mechanism-based approach which may help identify novel drugs and/or develop new therapeutic regimens for the treatment of prostate cancers.
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Affiliation(s)
- D G Tang
- Department of Radiation Oncology, Wayne State University, Detroit, Michigan 48202, USA.
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Klein KA, Reiter RE, Redula J, Moradi H, Zhu XL, Brothman AR, Lamb DJ, Marcelli M, Belldegrun A, Witte ON, Sawyers CL. Progression of metastatic human prostate cancer to androgen independence in immunodeficient SCID mice. Nat Med 1997; 3:402-8. [PMID: 9095173 DOI: 10.1038/nm0497-402] [Citation(s) in RCA: 290] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Prostate cancer mortality results from metastasis to bone and hormone-independent tumor growth. Models to study these progressive changes are lacking. Here we describe the propagation of advanced human prostate cancer by direct transfer of surgical samples from patients into immune-deficient male SCID mice. Explants from six of eight patients formed prostate tumors and two showed unique cytogenetic, biologic and molecular features that were retained through six or more passages. One grew in an androgen-independent fashion, whereas the second formed tumors that regressed following castration then regrew. Micrometastatic disease was detected in the hematopoietic tissues of half of the recipient mice. Thus selected specimens of advanced human prostate cancer can be propagated in SCID mice in a manner that recapitulates the clinical transition from androgen-sensitive to androgen-independent growth, accompanied by micrometastasis.
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Affiliation(s)
- K A Klein
- Department of Medicine, UCLA School of Medicine 90095-1678, USA
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Bladou F, Vessella RL, Buhler KR, Ellis WJ, True LD, Lange PH. Cell proliferation and apoptosis during prostatic tumor xenograft involution and regrowth after castration. Int J Cancer 1996; 67:785-90. [PMID: 8824549 DOI: 10.1002/(sici)1097-0215(19960917)67:6<785::aid-ijc6>3.0.co;2-n] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The biological mechanisms involved in androgen-dependent and -independent prostate cancer growth after castration were analyzed in the LuCaP 23.1 human prostate cancer xenograft model. Athymic mice (n = 82) bearing LuCaP 23.1 xenograft were castrated and tumors were harvested at different time points from day 0 to day 112 post castration. In each group of mice, tumor growth rate (TGR), serum PSA concentration, percentage of tumor cells incorporating bromodeoxyuridine (BUdR index), percentage of apoptotic tumor cells assessed by morphological analysis (apoptotic index), and presence of apoptosis-related DNA "ladder" were analyzed. Castration induced a significant decrease in TGR and serum PSA from day 1 to day 7, and a progressive increase in the 2 parameters from day 14 to day 112, heralding androgen-independent tumor relapse. Meanwhile the BUdR and apoptotic indexes varied as follows after castration: an increase was noted for both at day 3, a significant increase in apoptotic index with a decrease in BUdR index from day 5 to day 14, and a progressive decrease in apoptotic index while BUdR index remained at 50% of the pre-castration value from day 28 to day 112. DNA ladder was present sparsely in tumors grown in non-castrated hosts, universally present in tumors from day 1 to day 28 post castration, and frequent in tumors from day 56 to 112. Castration-induced effects in LuCaP 23.1 tumors were characterized by an increase in number of apoptotic cells and a decrease in proliferative activity. The androgen-independent tumor relapse after castration was associated with a low apoptotic index with no increase in proliferative activity.
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Affiliation(s)
- F Bladou
- Department of Urology, University of Washington Medical School, Seattle, USA
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49
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Wright GL, Grob BM, Haley C, Grossman K, Newhall K, Petrylak D, Troyer J, Konchuba A, Schellhammer PF, Moriarty R. Upregulation of prostate-specific membrane antigen after androgen-deprivation therapy. Urology 1996; 48:326-34. [PMID: 8753752 DOI: 10.1016/s0090-4295(96)00184-7] [Citation(s) in RCA: 465] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES To determine the expression of prostate-specific membrane antigen (PSMA) before and after androgen-deprivation therapy and to compare PSMA expression with prostate-specific antigen (PSA) expression. METHODS We studied specimens from 20 patients with prostate cancer undergoing medical or surgical castration or combination androgen-deprivation therapy in whom matched pretreatment and post-treatment tissue specimens were available and 16 patients in whom only a post-treatment specimen was available. The expression of PSMA and PSA in the tissue specimens was determined by immunoperoxidase staining. The extent of staining was calculated by multiplying the percent of antigen-positive tumor cells by the staining intensity to arrive at a stain index for each biomarker. An in vitro study assessed the concentration of PSMA and PSA in extracts of LNCaP cells cultured in the presence or absence of androgen as determined by immunoassays and Western blot analysis. RESULTS PSMA reactivity was found to be increased in 55% (11 of 20) of post-treatment primary tissues and 100% (4 of 4) of post-treatment metastatic specimens. In contrast, PSA expression was found to be decreased in 70% (14 of 20) of post-treatment primary and 100% (4 of 4) of post-treatment metastatic specimens. Neither type of androgen-deprivation treatment nor tissue sensitivity to androgen deprivation appeared to influence degree of biomarker expression. PSMA was found to be downregulated and PSA upregulated when LNCaP cells were cultured in the presence of testosterone or dihydrotestosterone. CONCLUSIONS The enhanced expression of PSMA in tissues and LNCaP cells after androgen deprivation suggests that PSMA is upregulated in the majority of prostate carcinomas after androgen treatment. The high expression in metastatic tissues strongly suggests that PSMA may be a clinically useful target for antibody-and genetic-directed therapy of prostate cancer that recurs after androgen deprivation. The mechanism whereby androgens suppress the expression of PSMA, and the association of PSMA with the development of hormone-independent prostate cancers, will require further study.
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Affiliation(s)
- G L Wright
- Department of Microbiology and Immunology, Eastern Virginia Medical School, Norfolk 23501, USA
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