CD44 expression is a feature of prostatic small cell carcinoma and distinguishes it from its mimickers. Hum Pathol. 2009;40:252-258. [PMID: 18835619 DOI: 10.1016/j.humpath.2008.07.014]

ETV5 reduces androgen receptor expression and induces neural stem-like properties during neuroendocrine prostate cancer development

Neuroendocrine prostate cancer (NEPC), an aggressive subtype induced by hormone therapy, lacks effective treatments. This study explored the role of E26 transformation-specific variant 5 (ETV5) in NEPC development. Analysis of multiple prostate cancer datasets revealed that NEPC is characterized by significantly elevated ETV5 expression compared to other subtypes. ETV5 expression increased progressively under hormone therapy through epigenetic modifications. ETV5 induced neural stem-like features in prostate cancer cells and facilitated their differentiation into NEPC under hormone treatment conditions, both in vitro and in vivo. Our molecular mechanistic study identified PBX3 and TLL1 as target genes of ETV5 that contribute to ETV5 overexpression-induced castration resistance and stemness. Notably, obeticholic acid, identified as an ETV5 inhibitor in this study, exhibited promising efficacy in suppressing NEPC development. This study highlights ETV5 as a key transcription factor that facilitates NEPC development and underscores its potential as a therapeutic target for this aggressive cancer subtype.

PET radiotracers for whole-body in vivo molecular imaging of prostatic neuroendocrine malignancies

Prostatic neuroendocrine malignancies represent a spectrum of diseases. Treatment-induced neuroendocrine differentiation (tiNED) in hormonally treated adenocarcinoma has been the subject of a large amount of recent research. However, the identification of neuroendocrine features in treatment-naïve prostatic tumor raises a differential diagnosis between prostatic adenocarcinoma with de novo neuroendocrine differentiation (dNED) versus one of the primary prostatic neuroendocrine tumors (P-NETs) and carcinomas (P-NECs). While [18F]FDG is being used as the main PET radiotracer in oncologic imaging and reflects cellular glucose metabolism, other molecules labeled with positron-emitting isotopes, mainly somatostatin-analogues labeled with 68Ga and prostate-specific membrane antigen (PSMA)-ligands labeled with either 18F or 68Ga, are now routinely used in departments of nuclear medicine and molecular imaging, and may be advantageous in imaging prostatic neuroendocrine malignancies. Still, the selection of the preferred PET radiotracer in such cases might be challenging. In the current review, we summarize and discuss published data on these different entities from clinical, biological, and molecular imaging standpoints. Specifically, we review the roles that [18F]FDG, radiolabeled somatostatin-analogues, and radiolabeled PSMA-ligands play in these entities in order to provide the reader with practical recommendations regarding the preferred PET radiotracers for imaging each entity. In cases of tiNED, we conclude that PSMA expression may be low and that [18F]FDG or radiolabeled somatostatin-analogues should be preferred for imaging. In cases of prostatic adenocarcinoma with dNED, we present data that support the superiority of radiolabeled PSMA-ligands. In cases of primary neuroendocrine malignancies, the use of [18F]FDG for imaging high-grade P-NECs and radiolabeled somatostatin-analogues for imaging well-differentiated P-NETs is recommended. KEY POINTS: • The preferred PET radiotracer for imaging prostatic neuroendocrine malignancies depends on the specific clinical scenario and pathologic data. • When neuroendocrine features result from hormonal therapy for prostate cancer, PET-CT should be performed with [18F]FDG or radiolabeled somatostatin-analogue rather than with radiolabeled PSMA-ligand. • When neuroendocrine features are evident in newly diagnosed prostate cancer, differentiating adenocarcinoma from primary neuroendocrine malignancy is challenging but crucial for selection of PET radiotracer and for clinical management.

Near-Infrared Photoimmunotherapy (NIR-PIT) in Urologic Cancers

Near-infrared photoimmunotherapy (NIR-PIT) is a novel molecularly-targeted therapy that selectively kills cancer cells by systemically injecting an antibody-photoabsorber conjugate (APC) that binds to cancer cells, followed by the application of NIR light that drives photochemical transformations of the APC. APCs are synthesized by selecting a monoclonal antibody that binds to a receptor on a cancer cell and conjugating it to IRDye700DX silica-phthalocyanine dye. Approximately 24 h after APC administration, NIR light is delivered to the tumor, resulting in nearly-immediate necrotic cell death of cancer cells while causing no harm to normal tissues. In addition, NIR-PIT induces a strong immunologic effect, activating anti-cancer immunity that can be further boosted when combined with either immune checkpoint inhibitors or immune suppressive cell-targeted (e.g., regulatory T cells) NIR-PIT. Currently, a global phase III study of NIR-PIT in recurrent head and neck squamous cell carcinoma is ongoing. The first APC and NIR laser systems were approved for clinical use in September 2020 in Japan. In the near future, the clinical applications of NIR-PIT will expand to other cancers, including urologic cancers. In this review, we provide an overview of NIR-PIT and its possible applications in urologic cancers.

Molecular and Functional Links between Neurodevelopmental Processes and Treatment-Induced Neuroendocrine Plasticity in Prostate Cancer Progression

Simple Summary

Treatment-induced neuroendocrine prostate cancer (t-NEPC) is a subtype of castration-resistant prostate cancer (CRPC) which develops under prolonged androgen deprivation therapy. The mechanisms and pathways underlying the t-NEPC are still poorly understood and there are no effective treatments available. Here, we summarize the literature on the molecules and pathways contributing to neuroendocrine phenotype in prostate cancer in the context of their known cellular neurodevelopmental processes. We also discuss the role of tumor microenvironment in neuroendocrine plasticity, future directions, and therapeutic options under clinical investigation for neuroendocrine prostate cancer.

Abstract

Neuroendocrine plasticity and treatment-induced neuroendocrine phenotypes have recently been proposed as important resistance mechanisms underlying prostate cancer progression. Treatment-induced neuroendocrine prostate cancer (t-NEPC) is highly aggressive subtype of castration-resistant prostate cancer which develops for one fifth of patients under prolonged androgen deprivation. In recent years, understanding of molecular features and phenotypic changes in neuroendocrine plasticity has been grown. However, there are still fundamental questions to be answered in this emerging research field, for example, why and how do the prostate cancer treatment-resistant cells acquire neuron-like phenotype. The advantages of the phenotypic change and the role of tumor microenvironment in controlling cellular plasticity and in the emergence of treatment-resistant aggressive forms of prostate cancer is mostly unknown. Here, we discuss the molecular and functional links between neurodevelopmental processes and treatment-induced neuroendocrine plasticity in prostate cancer progression and treatment resistance. We provide an overview of the emergence of neurite-like cells in neuroendocrine prostate cancer cells and whether the reported t-NEPC pathways and proteins relate to neurodevelopmental processes like neurogenesis and axonogenesis during the development of treatment resistance. We also discuss emerging novel therapeutic targets modulating neuroendocrine plasticity.

Neuroendocrine Carcinoma as an Independent Prognostic Factor for Patients With Prostate Cancer: A Population-Based Study

BACKGROUND

Neuroendocrine carcinoma (NEC) is a rare and highly malignant variation of prostate adenocarcinoma. We aimed to investigate the prognostic value of NEC in prostate cancer.

METHODS

A total of 530440 patients of prostate cancer, including neuroendocrine prostate cancer (NEPC) and adenocarcinoma from 2004 to 2018 were obtained from the national Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM), multivariable Cox proportional hazard model, Kaplan-Meier method and subgroup analysis were performed in our study.

RESULTS

NEPC patients were inclined to be older at diagnosis (Median age, 69(61-77) vs. 65(59-72), P< 0.001) and had higher rates of muscle invasive disease (30.9% vs. 9.2%, P < 0.001), lymph node metastasis (32.2% vs. 2.2%, P < 0.001), and distal metastasis (45.7% vs. 3.6%, P < 0.001) compared with prostate adenocarcinoma patients. However, the proportion of NEPC patients with PSA levels higher than 4.0 ng/mL was significantly less than adenocarcinoma patients (47.3% vs. 72.9%, P<0.001). NEPC patients had a lower rate of receiving surgery treatment (28.8% vs. 43.9%, P<0.001), but they had an obviously higher rate of receiving chemotherapy (57.9% vs. 1.0%, P<0.001). A Cox regression analysis demonstrated that the NEPC patients faced a remarkably worse OS (HR = 2.78, 95% CI = 2.34-3.31, P < 0.001) and CSS (HR = 3.07, 95% CI = 2.55-3.71, P < 0.001) compared with adenocarcinoma patients after PSM. Subgroup analyses further suggested that NEPC patients obtained significantly poorer prognosis across nearly all subgroups.

CONCLUSION

The prognosis of NEPC was worse than that of adenocarcinoma among patients with prostate cancer. The histological subtype of NEC is an independent prognostic factor for patients with prostate cancer.

MicroRNAs in treatment-induced neuroendocrine differentiation in prostate cancer

Prostate cancer is a condition commonly associated with men worldwide. Androgen deprivation therapy remains one of the targeted therapies. However, after some years, there is biochemical recurrence and metastatic progression into castration-resistant prostate cancer (CRPC). CRPC cases are treated with second-line androgen deprivation therapy, after which, these CRPCs transdifferentiate to form neuroendocrine prostate cancer (NEPC), a highly aggressive variant of CRPC. NEPC arises via a reversible transdifferentiation process, known as neuroendocrine differentiation (NED), which is associated with altered expression of lineage markers such as decreased expression of androgen receptor and increased expression of neuroendocrine lineage markers including enolase 2, chromogranin A and synaptophysin. The etiological factors and molecular basis for NED are poorly understood, contributing to a lack of adequate molecular biomarkers for its diagnosis and therapy. Therefore, there is a need to fully understand the underlying molecular basis for this cancer. Recent studies have shown that microRNAs (miRNAs) play a key epigenetic role in driving therapy-induced NED in prostate cancer. In this review, we briefly describe the role of miRNAs in prostate cancer and CRPCs, discuss some key players in NEPCs and elaborate on miRNA dysregulation as a key epigenetic process that accompanies therapy-induced NED in metastatic CRPC. This understanding will contribute to better clinical management of the disease.

Neuroendocrine cells of prostate cancer: biologic functions and molecular mechanisms

Prostate cancer (PCa) is a major health risk for older men worldwide. Existing systemic therapies mostly target androgen receptor (AR). Although treatments are initially effective, the disease always recurs. A potential mechanism for the treatment failure is that PCa contains, in addition to the AR-positive luminal type tumor cells, a small component of neuroendocrine (NE) cells. The function of NE cells in PCa remains poorly understood, and one important characteristic of these cells is their lack of expression of AR and resistance to hormonal therapy. In addition, many patients develop the more aggressive small-cell neuroendocrine carcinoma (SCNC) after hormonal therapy. Although this clinical phenomenon of disease transformation from adenocarcinoma to SCNC is well established, the cell of origin for SCNC remains unclear. Recently, loss of function of Rb and TP53 and amplification and overexpression of MYCN and Aurora A kinase have been identified as important biomarkers and potential disease drivers. In this article, we systematically review the histology of normal prostate and prostate cancer including the main histologic types: adenocarcinoma and SCNC. We also review the findings from many studies using cellular and animal models as well as human specimens that attempt to understand the molecular mechanisms of treatment failure, disease progression, and tumor transformation from adenocarcinoma to SCNC.

Morphologic, Molecular and Clinical Features of Aggressive Variant Prostate Cancer

The term aggressive variant prostate cancer (AVPCa) refers to androgen receptor (AR)-independent anaplastic forms of prostate cancer (PCa), clinically characterized by a rapidly progressive disease course. This involves hormone refractoriness and metastasis in visceral sites. Morphologically, AVPCa is made up of solid sheets of cells devoid of pleomorphism, with round and enlarged nuclei with prominent nucleoli and slightly basophilic cytoplasm. The cells do not show the typical architectural features of prostatic adenocarcinoma and mimic the undifferentiated carcinoma of other organs and locations. The final diagnosis is based on the immunohistochemical expression of markers usually seen in the prostate, such as prostate-specific membrane antigen (PSMA). A subset of AVPCa can also express neuroendocrine (NE) markers such as chromogranin A, synaptophysin and CD56. This letter subset represents an intermediate part of the spectrum of NE tumors which ranges from small cell to large cell carcinoma. All such tumors can develop following potent androgen receptor pathway inhibition. This means that castration-resistant prostate cancer (CRPCa) transdifferentiates and becomes a treatment-related NE PCa in a clonally divergent manner. The tumors that do not show NE differentiation might harbor somatic and/or germline alterations in the DNA repair pathway. The identification of these subtypes has direct clinical relevance with regard to the potential benefit of platinum-based chemotherapy, poly (ADP-ribose) polymerase inhibitors and likely further therapies.

B7-H4 is a potential prognostic biomarker of prostate cancer

B7-H4 is a member of B7 family which regulates immune responses by delivering costimulatory signals. However, it negatively regulates T cell-mediated immunity and may play an important role in tumor immune evasion. Although several studies have been reported that expression of B7-H4 is elevated in the several types of human cancer with a poor clinical outcome, its clinical significance in the prostate cancer (PCa) has not been well studied. In this study, we investigated the clinical significance of B7-H4 in human PCa and determined if B7-H4 expression is associated with the cancer cell stemness in PCa. Our studies show that expression of B7-H4 is correlated with the pathologic tumor (pT) stage and the clinical stage of PCa. The Kaplan-Meier survival analysis revealed that PCa patients with high expression of B7-H4 exhibits a shorter overall survival (OS) rate. Univariate and multivariate Cox regression analysis indicated that B7-H4 is an independent poor prognostic factor of PCa. In addition, the expression of B7-H4 is correlated with the cancer cell stemness associated genes expression in PCa. Further, our studies show that B7-H4 regulates cancer cell stemness associated genes expression and effects on the cell cycle and PI3K/Akt signaling related genes expression in PCa. These results indicate that B7-H4 expression is associated with cancer cell stemness, and B7-H4 is a potential prognostic biomarker and a therapeutic target of PCa.

Morphologic Spectrum of Neuroendocrine Tumors of the Prostate: An Updated Review

CONTEXT.—

The incidence of neuroendocrine tumors of the prostate increases after hormonal therapy. Neuroendocrine tumors possess a broad spectrum of morphologic features and pose challenges in the pathologic diagnosis and clinical management of patients.

OBJECTIVE.—

To present a brief updated summary of neuroendocrine tumors of the prostate with an overview of their histopathologic and immunohistochemical profiles and differential diagnoses.

DATA SOURCES.—

Literature review, personal experience in the daily practice of pathologic diagnosis, and laboratory research.

CONCLUSIONS.—

Our understanding of neuroendocrine tumors of the prostate classification and diagnosis continues to evolve. These advances benefit the risk stratification and management of prostate cancer.

Low-serum prostate-specific antigen level predicts poor outcomes in patients with primary neuroendocrine prostate cancer

BACKGROUND

The rarities of primary neuroendocrine prostate cancer (NEPC) and primary adenocarcinoma with neuroendocrine differentiation (NE differentiation) mean that their clinical characteristics have not been fully elucidated.

MATERIALS AND METHODS

A total of 449 patients with NEPC, including 352 cases of pure NEPC and 97 cases of NE differentiation, together with 408 629 cases of prostate adenocarcinoma at diagnosis were retrieved from the Surveillance, Epidemiology, and End Results program (2010-2015). Clinical parameters and prognoses were compared between patients with different histological types of NEPC using the χ² test and Kaplan-Meier analysis, respectively. The prognostic value of prostate-specific antigen (PSA) in NEPC and adenocarcinoma was evaluated using Cox regression and the Kaplan-Meier method.

RESULTS

Pure NEPC had higher rates of visceral metastases (brain, lung, and liver: 4.58%, 26.72%, and 36.64%, respectively) but a lower rate of bone metastasis (65.65%) compared with NE differentiation and prostate adenocarcinoma. Moreover, patients diagnosed with pure NEPC had a poorer outcome (median survival time: 10 months) compared with patients with NE differentiation (26 months) and prostate adenocarcinoma (median survival time not reached). Using PSA 4.1 to 10 ng/mL as the reference, the adjusted hazard ratios (HRs) for PSA lower than or equal to 4.0 ng/mL were 2.24 (95% confidence interval [CI]: 1.11-4.55, P = .025) in the NE differentiation group and 1.57 (95% CI: 1.11-2.23, P = .011) in the pure NEPC group.

CONCLUSIONS

Patients with NE differentiation had different clinical characteristics and a better prognosis than patients with pure NEPC. In addition, low-serum PSA levels were associated with a poorer prognosis in patients with either NEPC or NE differentiation.

Neuroendocrine Differentiation in Prostate Cancer: Emerging Biology, Models, and Therapies

Although a de novo clinical presentation of small cell neuroendocrine carcinoma of the prostate is rare, a subset of patients previously diagnosed with prostate adenocarcinoma may develop neuroendocrine features in later stages of castration-resistant prostate cancer (CRPC) progression as a result of treatment resistance. Despite sharing clinical, histologic, and some molecular features with other neuroendocrine carcinomas, including small cell lung cancer, castration-resistant neuroendocrine prostate cancer (CRPC-NE) is clonally derived from prostate adenocarcinoma. CRPC-NE therefore retains early prostate cancer genomic alterations and acquires new molecular changes making them resistant to traditional CRPC therapies. This review focuses on recent advances in our understanding of CRPC-NE biology, the transdifferentiation/plasticity process, and development and characterization of relevant CRPC-NE preclinical models.

Application of Prostate Cancer Models for Preclinical Study: Advantages and Limitations of Cell Lines, Patient-Derived Xenografts, and Three-Dimensional Culture of Patient-Derived Cells

Various preclinical models have been developed to clarify the pathophysiology of prostate cancer (PCa). Traditional PCa cell lines from clinical metastatic lesions, as exemplified by DU-145, PC-3, and LNCaP cells, are useful tools to define mechanisms underlying tumorigenesis and drug resistance. Cell line-based experiments, however, have limitations for preclinical studies because those cells are basically adapted to 2-dimensional monolayer culture conditions, in which the majority of primary PCa cells cannot survive. Recent tissue engineering enables generation of PCa patient-derived xenografts (PDXs) from both primary and metastatic lesions. Compared with fresh PCa tissue transplantation in athymic mice, co-injection of PCa tissues with extracellular matrix in highly immunodeficient mice has remarkably improved the success rate of PDX generation. PDX models have advantages to appropriately recapitulate the molecular diversity, cellular heterogeneity, and histology of original patient tumors. In contrast to PDX models, patient-derived organoid and spheroid PCa models in 3-dimensional culture are more feasible tools for in vitro studies for retaining the characteristics of patient tumors. In this article, we review PCa preclinical model cell lines and their sublines, PDXs, and patient-derived organoid and spheroid models. These PCa models will be applied to the development of new strategies for cancer precision medicine.

Wnt/Beta-Catenin Signaling and Prostate Cancer Therapy Resistance

Metastatic or locally advanced prostate cancer (PCa) is typically treated with androgen deprivation therapy (ADT). Initially, PCa responds to the treatment and regresses. However, PCa almost always develops resistance to androgen deprivation and progresses to castrate-resistant prostate cancer (CRPCa), a currently incurable form of PCa. Wnt/β-Catenin signaling is frequently activated in late stage PCa and contributes to the development of therapy resistance. Although activating mutations in the Wnt/β-Catenin pathway are not common in primary PCa, this signaling cascade can be activated through other mechanisms in late stage PCa, including cross talk with other signaling pathways, growth factors and cytokines produced by the damaged tumor microenvironment, release of the co-activator β-Catenin from sequestration after inhibition of androgen receptor (AR) signaling, altered expression of Wnt ligands and factors that modulate the Wnt signaling, and therapy-induced cellular senescence. Research from genetically engineered mouse models indicates that activation of Wnt/β-Catenin signaling in the prostate is oncogenic, enables castrate-resistant PCa growth, induces an epithelial-to-mesenchymal transition (EMT), promotes neuroendocrine (NE) differentiation, and confers stem cell-like features to PCa cells. These important roles of Wnt/β-Catenin signaling in PCa progression underscore the need for the development of drugs targeting this pathway to treat therapy-resistant PCa.

Poorly Differentiated Small-Cell-Type Neuroendocrine Carcinoma of the Prostate: A Case Report and Literature Review

Neuroendocrine cells are widespread throughout the body and can give rise of neuroendocrine tumors due to abnormal growth of the chromaffin cells. Neuroendocrine tumors divide into many subtypes based on tumor grade (Ki-67 index and mitotic count) and differentiation. These tumors can be further divided into secretory and nonsecretory types based on the production of peptide hormone by tumor cells. Poorly differentiated small-cell-type neuroendocrine tumors are one of the subtypes of neuroendocrine tumors. These tumors are less common; however, they tend to be locally invasive and aggressive in behavior with poor overall median survival. Treatment of the nonsecretory small-cell type is modeled to small-cell lung cancer with a regimen consisting of platinum-based chemotherapy and etoposide with variable response. Here, we present a case of poorly differentiated small-cell neuroendocrine tumor originating from the prostate.

EMT, stemness and tumor plasticity in aggressive variant neuroendocrine prostate cancers

Neuroendocrine/Aggressive Variant Prostate Cancers are lethal variants of the disease, with an aggressive clinical course and very short responses to conventional therapy. The age-adjusted incidence rate for this tumor sub-type has steadily increased over the past 20 years in the United States, with no reduction in the associated mortality rate. The molecular networks fueling its emergence and sustenance are still obscure; however, many factors have been associated with the onset and progression of neuroendocrine differentiation in clinically typical adenocarcinomas including loss of androgen-receptor expression and/or signaling, conventional therapy, and dysregulated cytokine function. "Tumor-plasticity" and the ability to dedifferentiate into alternate cell lineages are central to this process. Epithelial-to-mesenchymal (EMT) signaling pathways are major promoters of stem-cell properties in prostate tumor cells. In this review, we examine the contributions of EMT-induced cellular-plasticity and stem-cell signaling pathways to the progression of Neuroendocrine/Aggressive Variant Prostate Cancers in the light of potential therapeutic opportunities.

Oxibendazole inhibits prostate cancer cell growth

Prostate cancer (PCa) is one of the most common malignancies among men and is the second leading cause of cancer-associated mortality in the developed world. Androgen deprivation therapy (ADT) is the most common treatment for PCa. However, the majority of androgen-sensitive PCa patients will eventually develop resistance to ADT and the disease will become androgen-independent. There is, therefore, an immediate requirement to develop effective therapeutic techniques towards the treatment of recurrent PCa. Oxibendazole (OBZ) is an anthelmintic drug that has also shown promise in the treatment of malignancies. In the present study, the capability of OBZ to repress the growth of PCa cells was assessed in human androgen-independent PCa 22Rv1 and PC-3 cell lines. The growth of the 22Rv1 and PC-3 cell lines, as assessed with a trypan blue exclusion assay, was markedly inhibited by OBZ treatment in vitro, with half-maximal inhibitory concentration values of 0.25 and 0.64 µM, respectively. The mean size of 22Rv1 tumors in nude mice treated with OBZ (25 mg/kg/day) was 47.96% smaller than that of the control mice. Treatment with OBZ increased the expression of microRNA-204 (miR-204), as determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and the level of p53 as determined with western blotting, two well-characterized tumor suppressor genes. When miR-204 expression was knocked down by introduction of an miR-204 inhibitor, the inhibitory effect of OBZ was markedly reduced; however, when it was overexpressed, the inhibitory efficiency of OBZ was markedly higher, indicating that upregulation of miR-204 is key for the efficacy of OBZ. Additionally, OBZ was demonstrated with RT-qPCR to repress the expression of the androgen receptor, and by western blotting to reduce prostate-specific androgen in 22Rv1 cells. The results suggest that OBZ has potential for clinical use in the treatment of recurrent PCa.

Cervical Carcinomas With Neuroendocrine Differentiation: A Report of 28 Cases With Immunohistochemical Analysis and Molecular Genetic Evidence of Common Clonal Origin With Coexisting Squamous and Adenocarcinomas

Cervical neuroendocrine carcinomas are rare, aggressive tumors and their immunohistochemical features and clonal relationship to coexisting tumors are incompletely described. Twenty-eight cases were identified (17 small cell, 9 large cell, and 2 mixed), 10 of which had an invasive squamous or adenocarcinoma component. Staining for synaptophysin, chromogranin A, TTF1, c-kit, CD44, and p16 was performed. Analyses for loss of heterozygosity (LOH) at 5 polymorphic microsatellite markers (D3S1300, D9S171, D11S914, D13S319, and TP53) and X-chromosome inactivation were performed. Of 17 cases with available blocks, 13 (76%) were synaptophysin+, 8 (47%) were chromogranin A+, 8 (47%) were TTF1+, 7 (41%) were c-kit+, and 6 (35%) were CD44+. Strong patchy or strong diffuse p16 staining was seen in all cases. LOH and X-chromosome inactivation analysis were performed for 17 cases, 8 of which had a coexisting squamous or adenocarcinoma component. Five of the 8 (63%) cases with 2 components showed allelic loss in both components. All 5 of these cases demonstrated identical LOH between the neuroendocrine and squamous or adenocarcinoma components. Nonrandom X-chromosome inactivation was seen in the neuroendocrine and other components in 4 of the 8 cases. In all 4 cases the pattern of inactivation was identical between the 2 components. Cervical neuroendocrine carcinomas have features similar to other extrapulmonary neuroendocrine carcinomas, including expression of TTF1, c-kit, and CD44. Consistent staining for p16 is also seen. Concordant genetic alterations support common clonal origin for neuroendocrine carcinomas with a coexisting squamous or adenocarcinoma component.

CD44 regulates prostate cancer proliferation, invasion and migration via PDK1 and PFKFB4

Our recent studies have shown that CD44, a cell-surface protein with functions in many biologic processes, involved in glucose metabolism of prostate cancer cells. However, the molecular mechanisms of the regulation need to be further elucidated. In present study, LNCaP cells infected with lentivirus vector overexpressing CD44. The expression levels of key enzymes in glucose metabolism known as PDK1 and PFKFB4 were determined using QRT-PCR and western blot. PDK1 and PFKFB4 in LNCaP and PC3 cells were knocked down with shRNA respectively, and then cell proliferation, invasion and cell migration assay were performed. We found that overexpression of CD44 increased expression levels of PDK1 and PFKFB4 in LNCaP cells. Silencing of PDK1 and PFKFB4 could decrease cell proliferation, inhibit invasion and migration ability of prostate cancer cells. In addition, CD44 inhibitor could decrease glucose consumption and increase ROS levels of PC-3 cells significantly, as well as sensitize PC-3 cells to docetaxel. Taken together, CD44 could modulate aggressive phenotype of prostate cancer cells, by regulation of the expression of PDK1 and PFKFB4. CD44 may be a novel potential therapeutic target.

Strategies to avoid treatment-induced lineage crisis in advanced prostate cancer

The increasing potency of therapies that target the androgen receptor (AR) signalling axis has correlated with a rise in the proportion of patients with prostate cancer harbouring an adaptive phenotype, termed treatment-induced lineage crisis. This phenotype is characterized by features that include soft-tissue metastasis and/or resistance to standard anticancer therapies. Potent anticancer treatments might force cancer cells to evolve and develop alternative cell lineages that are resistant to primary therapies, a mechanism similar to the generation of multidrug- resistant microorganisms after continued antibiotic use. Herein, we assess the hypothesis that treatment-adapted phenotypes harbour reduced AR expression and/or activity, and acquire compensatory strategies for cell survival. We highlight the striking similarities between castration-resistant prostate cancer and triple-negative breast cancer, another poorly differentiated endocrine malignancy. Alternative treatment paradigms are needed to avoid therapy-induced resistance. Herein, we present a new clinical trial strategy designed to evaluate the potential of rapid drug cycling as an approach to delay the onset of resistance and treatment-induced lineage crisis in patients with metastatic castration-resistant prostate cancer.

Co-Expression of Putative Cancer Stem Cell Markers CD44 and CD133 in Prostate Carcinomas

Cancer stem cells (CSCs) are the main players of prostate tumorigenesis thus; characterization of CSCs can pave the way for understanding the early detection, drug resistance, metastasis and relapse. The current study was conducted to evaluate the expression level and clinical significance of the potential CSC markers CD44 and CD133 in a series of prostate tissues. One hundred and forty eight prostate tissues composed of prostate cancer (PCa), high-grade prostatic intraepithelial neoplasia (HGPIN), and benign prostate hyperplasia (BPH) were immunostained for the putative CSC markers CD44 and CD133. Subsequently, the correlation between the expression of these markers and the clinicopathological variables was examined. A higher level of CD44 expression was observed in 42% of PCa, 57% of HGPIN, and 42% BPH tissues. In the case of CD133 expression PCa, HGPIN, and BPH samples demonstrated high immunoreactivity in 46%, 43%, and 42% of cells, respectively. Statistical analysis showed an inverse significant correlation between CD44 expression with Gleason score of PCa (P = 0.02), while no significant correlation was observed between CD133 expression and clinicopathological parameters. A significant reciprocal correlation was observed between the expression of two putative CSC markers CD44 and CD133 in PCa specimens while not indicating clinical significance. Further clinical investigation is required to consider these markers as targets of new therapeutic strategies for PCa.

B7-H4 expression in ovarian serous carcinoma: a study of 306 cases

The B7 family of immune costimulatory ligands is a group of cell surface proteins that bind to the surface receptors of lymphocytes to fine-tune immune responses. The aberrant expression of these proteins plays a key role in tumor immune evasion. Immunotherapy targeting certain B7 family members, including programmed death ligand 1, has proven quite effective in suppressing tumor growth. However, why such therapy works in only a subgroup of tumors is unclear. We hypothesized that other B7 family members, either alone or in concert with programmed death ligand 1, play a crucial role in tumor pathogenesis and progression. We therefore examined the expression of a newly discovered B7 family member, B7-H4, in 306 cases of ovarian serous carcinoma by immunohistochemistry. We found that 91% (267/293) of the high-grade ovarian serous carcinomas and 69% (9/13) of the low-grade ovarian serous carcinomas expressed B7-H4. The difference between B7-H4 expression in high-grade and low-grade ovarian serous carcinoma was statistically significant (P=.002). Moreover, B7-H4 protein expression in high-grade serous carcinoma was associated with tumor stage (P<.01) but not overall survival or disease-free survival. In conclusion, B7-H4 is frequently expressed in ovarian serous carcinomas, especially high-grade serous carcinomas, and may represent a novel immunotherapeutic target in this cancer.

Neuroendocrine Tumors of the Prostate: Emerging Insights from Molecular Data and Updates to the 2016 World Health Organization Classification

Neuroendocrine neoplasms of the prostate represent a multifarious group of tumors that exist both in pure forms and associated with prostatic adenocarcinoma. Morphologically, neuroendocrine cells in prostate neoplasms can range from being indistinguishable from surrounding prostate adenocarcinoma cells to having high-grade neuroendocrine appearances similar to neuroendocrine malignancies of other organs. On the molecular level, neuroendocrine malignancies arising in the setting of prostate adenocarcinoma have been the subject of a large amount of recent research, most of which has supported the conclusion that neuroendocrine malignancy within the prostate develops as a transdifferentiation from prostate adenocarcinoma. There has not, however, been substantial investigation into rare, pure neuroendocrine malignancies and the possibility that these tumors may have a different cell of origin and molecular genesis. Here, we discuss the morphologic spectrum of malignant neuroendocrine prostate neoplasms and review the most recent molecular data on the subject of malignant neuroendocrine differentiation in prostatic adenocarcinoma. In reflection of the most recent data, we also discuss diagnostic classification of prostate neuroendocrine tumors with reference to the 2016 World Health Organization (WHO) classification. We discuss the reporting of these tumors, placing emphasis on the differentiation between pure and mixed neuroendocrine malignancies so that, in the least, they can be easily identified for the purposes of future clinical and laboratory-based investigation. Finally, we suggest a designation for an unclassifiable (or not otherwise specified) high-grade neuroendocrine prostate malignancy whose features do not easily place it into one of the WHO diagnostic entities.

A dual yet opposite growth-regulating function of miR-204 and its target XRN1 in prostate adenocarcinoma cells and neuroendocrine-like prostate cancer cells

Androgen deprivation therapy in prostate cancer (PCa) causes neuroendocrine differentiation (NED) of prostatic adenocarcinomas (PAC) cells, leading to recurrence of PCa. Androgen-responsive genes involved in PCa progression including NED remain largely unknown. Here we demonstrated the importance of androgen receptor (AR)-microRNA-204 (miR-204)-XRN1 axis in PCa cell lines and the rat ventral prostate. Androgens downregulate miR-204, resulting in induction of XRN1 (5′-3′ exoribonuclease 1), which we identified as a miR-204 target. miR-204 acts as a tumor suppressor in two PAC cell lines (LNCaP and 22Rv1) and as an oncomiR in two neuroendocrine-like prostate cancer (NEPC) cell lines (PC-3 and CL1). Importantly, overexpression of miR-204 and knockdown of XRN1 inhibited AR expression in PCa cells. Repression of miR-34a, a known AR-targeting miRNA, contributes AR expression by XRN1. Thus we revealed the AR-miR-204-XRN1-miR-34a positive feedback loop and a dual function of miR-204/XRN1 axis in prostate cancer.

Molecular aspects of prostate cancer with neuroendocrine differentiation

Neuroendocrine differentiation (NED), which is not uncommon in prostate cancer, is increases in prostate cancer after androgen-deprivation therapy (ADT) and generally appears in castration-resistant prostate cancer (CRPC). Neuroendocrine cells, which are found in normal prostate tissue, are a small subset of cells and have unique function in regulating the growth of prostate cells. Prostate cancer with NED includes different types of tumor, including focal NED, pure neuroendocrine tumor or mixed neuroendocrine-adenocarcinoma. Although more and more studies are carried out on NED in prostate cancer, the molecular components that are involved in NED are still poorly elucidated. We review neuroendocrine cells in normal prostate tissue, NED in prostate cancer, terminology of NED and biomarkers used for detecting NED in routine pathological practice. Some recently reported molecular components which drive NED in prostate cancer are listed in the review.

The Role of CD44 in Glucose Metabolism in Prostatic Small Cell Neuroendocrine Carcinoma

While prostatic adenocarcinomas are relatively indolent, some patients with advanced adenocarcinomas recur with small cell neuroendocrine carcinoma which is highly aggressive and lethal. Because glycolysis is a feature of malignancy and the degree of glycolysis generally correlates with tumor aggressiveness, we wanted to compare the metabolic differences and the molecular mechanisms involved between the two tumor types. In this study, and based on previous characterization, LNCaP and PC-3 prostate cancer cell lines were selected as models of prostatic adenocarcinoma and small cell neuroendocrine carcinoma, respectively. In addition to measuring glucose consumption, lactate secretion, and reactive oxygen species (ROS) levels, we performed metabolic profiling in these two model systems. The role of CD44 was studied by RNAi and lentivirus-mediated overexpression. Expression of key enzymes in glycolysis was studied using human tissue microarrays containing benign prostate, adenocarcinoma, and small cell neuroendocrine carcinoma. Results showed that glycolytic features of PC-3 cells were higher than that of LNCaP cells. PFKFB4 was overexpressed in human small cell carcinoma tissue versus adenocarcinoma tissue. CD44 regulated glucose metabolism, intracellular ROS, and cell proliferation in PC-3 cells. Inhibition of CD44 also sensitized PC-3 cells to carboplatin. In conclusion, this study suggests different pathways of glucose metabolism contribute to the disparate biologic behaviors of these two tumor types.

IMPLICATIONS

CD44 is an important regulator of glucose metabolism in small cell neuroendocrine carcinoma and may be an important therapeutic target.

Androgen-deprivation therapy-induced aggressive prostate cancer with neuroendocrine differentiation

Most prostate cancers (PCas) are classified as acinar type (conventional) adenocarcinoma which are composed of tumor cells with luminal differentiation including the expression of androgen receptor (AR) and prostate-specific antigen (PSA). There are also scattered neuroendocrine (NE) cells in every case of adenocarcinoma. The NE cells are quiesecent, do not express AR or PSA, and their function remains unclear. We have demonstrated that IL8-CXCR2-P53 pathway provides a growth-inhibitory signal and keeps the NE cells in benign prostate and adenocarcinoma quiescent. Interestingly, some patients with a history of adenocarcinoma recur with small cell neuroendocrine carcinoma (SCNC) after hormonal therapy, and such tumors are composed of pure NE cells that are highly proliferative and aggressive, due to P53 mutation and inactivation of the IL8-CXCR2-P53 pathway. The incidence of SCNC will likely increase due to the widespread use of novel drugs that further inhibit AR function or intratumoral androgen synthesis. A phase II trial has demonstrated that platinum-based chemotherapy may be useful for such therapy-induced tumors.

Diagnosis of prostatic neuroendocrine carcinoma: Two cases report and literature review

Two cases of prostatic neuroendocrine carcinoma (PNEC) imaged by computed tomography (CT) and magnetic resonance imaging (MRI), and literature review are presented. Early enhanced CT, MRI, especially diffusion-weighted image were emphasized, the complementary roles of ultrasound, CT, MRI, clinical and laboratory characteristic’s features in achieving accurate diagnosis were valued in the preoperative diagnosis of PNEC.

An ultra scale-down analysis of the recovery by dead-end centrifugation of human cells for therapy

An ultra scale-down method is described to determine the response of cells to recovery by dead-end (batch) centrifugation under commercially defined manufacturing conditions. The key variables studied are the cell suspension hold time prior to centrifugation, the relative centrifugal force (RCF), time of centrifugation, cell pellet resuspension velocities, and number of resuspension passes. The cell critical quality attributes studied are the cell membrane integrity and the presence of selected surface markers. Greater hold times and higher RCF values for longer spin times all led to the increased loss of cell membrane integrity. However, this loss was found to occur during intense cell resuspension rather than the preceding centrifugation stage. Controlled resuspension at low stress conditions below a possible critical stress point led to essentially complete cell recovery even at conditions of extreme centrifugation (e.g., RCF of 10000 g for 30 mins) and long (∼2 h) holding times before centrifugation. The susceptibility to cell loss during resuspension under conditions of high stress depended on cell type and the age of cells before centrifugation and the level of matrix crosslinking within the cell pellet as determined by the presence of detachment enzymes or possibly the nature of the resuspension medium. Changes in cell surface markers were significant in some cases but to a lower extent than loss of cell membrane integrity. Biotechnol. Bioeng. 2015;112: 997–1011. © 2014 Wiley Periodicals, Inc.

UK single centre experience of rare and atypical variant of castrate-resistant prostate cancer: Poorly differentiated neuroendocrine small-cell carcinoma

Background:

We report on the emergence of a rare and atypical variant of castrate-resistant prostate cancer (CRPC) that is characterised by transformation into poorly differentiated neuroendocrine small-cell carcinoma (NSCC). The existence of this variant was previously described in isolated case reports and small case-studies, but as yet there has been no UK series reported in the literature.

Methods:

Between January 2010 and January 2014, eight cases were presented in our local multi-disciplinary team meeting having a diagnosis of NSCC arising on a background of prostate cancer treated with androgen deprivation therapy. We performed a retrospective review of the clinical records of these patients, to identify the mode of presentation, diagnostic investigations, pathological characteristics, and subsequent treatment and survival outcomes.

Results:

The median patient age was 77 years (range, 68 – 84), with a median time interval of 25 months (range, 7 – 83) between the original diagnosis and subsequent transformation to NSCC. The median prostate-specific antigen (PSA) was 4 ng/ml, at presentation. Most patients presented with local progression, combined with high-volume and atypical sites of metastasis (e.g. brain, pancreas and penis). Patients developed a good initial response to platinum-based chemotherapy, but responses were short-lived and prognosis poor, with a median overall survival (OS) of 8 months.

Conclusion:

Prostate NSCC represents an atypical variant of CRPC with significant therapeutic and prognostic implications. Based on our observations, we have proposed a clinical algorithm for early diagnosis and appropriate management of these patients.

Overlap of CD44 expression between prostatic small cell carcinoma and acinar adenocarcinoma

Small cell carcinoma (SmCC) of the prostate is a rare and aggressive histologic subtype of the prostate cancer. It can sometimes mimic acinar adenocarcinoma with a high Gleason score (GS). A previous study showed that immunohistochemical staining for CD44 could help in the differential diagnosis of these 2 entities. In this study, we used 2 tissue microarrays including 63 cases of prostate cancer (18 pure SmCC, 37 pure acinar adenocarcinoma, and 8 mixed acinar adenocarcinoma and SmCC) to validate the value of CD44. When analyzed as a continuous variable, CD44 positivity was significantly higher in acinar adenocarcinoma with GS 8 than GS 9 to 10 (P = .027). However, the difference of CD44 expression between SmCC and acinar adenocarcinoma was insignificant. The current study fails to confirm the value of CD44 in differential diagnosis between prostatic SmCC and acinar adenocarcinoma.

Neuroendocrine differentiation in prostate cancer: novel morphological insights and future therapeutic perspectives

Neuroendocrine prostate cancer (NEPC) is an aggressive variant of prostate cancer that commonly arises in later stages of castration resistant prostate cancer (CRPC) The detection of NEPC has clinical implications as these patients are often treated with platinum chemotherapy rather than with androgen receptor targeted therapies. The poor molecular characterization of NEPC accounts in part for the lack of disease specific therapeutics. Several mechanisms are involved in NE differentiation, including inflammation and autophagy, and may actually represent future therapeutic targets for advanced NEPC patients. Furthermore, a growing body of evidence suggests a potential role of circulating tumor cells in the early diagnosis and treatment of NEPC. Here we summarize the recent findings on NEPC pathogenesis and we discuss the ongoing clinical trials and future perspectives for the treatment of NEPC patients.

TMPRSS2:ERG blocks neuroendocrine and luminal cell differentiation to maintain prostate cancer proliferation

The biological outcome of TMPRSS2:ERG chromosomal translocations in prostate cancer (PC) remains poorly understood. To address this, we compared the transcriptional effects of TMPRSS2:ERG expression in a transgenic mouse model with those of ERG knockdown in a TMPRSS2:ERG-positive PC cell line. This reveals that ERG represses the expression of a previously unreported set of androgen receptor (AR)-independent neuronal genes that are indicative of neuroendocrine (NE) cell differentiation-in addition to previously reported AR-regulated luminal genes. Cell sorting and proliferation assays performed after sustained ERG knockdown indicate that ERG drives proliferation and blocks the differentiation of prostate cells to both NE and luminal cell types. Inhibition of ERG expression in TMPRSS2:ERG-positive PC cells through blockade of AR signaling is tracked with increased NE gene expression. We also provide evidence that these NE cells are resistant to pharmacological AR inhibition and can revert to the phenotype of parental cells upon restoration of AR/ERG signaling. Our findings highlight an ERG-regulated mechanism capable of repopulating the parent tumor through the transient generation of an anti-androgen therapy-resistant cell population, suggesting that ERG may have a direct role in preventing resistance to anti-androgen therapy.

SOX2 expression in the developing, adult, as well as, diseased prostate

BACKGROUND

SOX2 is a member of SOX (SRY-related HMG box) family of transcription factors.

METHODS

in this study, we examined the expression of SOX2 in murine and human prostatic specimens by immunohistochemistry.

RESULTS

we found that SOX2 was expressed in murine prostates during budding morphogenesis and in neuroendocrine (NE) prostate cancer (PCa) murine models. Expression of SOX2 was also examined in human prostatic tissue. We found that SOX2 was expressed in 26 of 30 benign prostate hyperplasia (BPH) specimens. In these BPH samples, expression of SOX2 was limited to basal epithelial cells. In contrast, 24 of 25 primary PCa specimens were negative for SOX2. The only positive primary PCa was the prostatic NE tumor, which also showed co-expression of synaptophysin. Additionally, the expression of SOX2 was detected in all prostatic NE tumor xenograft lines. Furthermore, we have examined the expression of SOX2 on a set of tissue microarrays consisting of metastatic PCa tissues. Expression of SOX2 was detected in at least one metastatic site in 15 of 24 patients with metastatic castration-resistant PCa; and the expression of SOX2 was correlated with synaptophysin.

CONCLUSIONS

SOX2 was expressed in developing prostates, basal cells of BPH, as well as prostatic NE tumors.

Aggressive variants of castration-resistant prostate cancer

A subset of patients with advanced castration-resistant prostate cancer may eventually evolve into an androgen receptor (AR)-independent phenotype, with a clinical picture associated with the development of rapidly progressive disease involving visceral sites and hormone refractoriness, often in the setting of a low or modestly rising serum prostate-specific antigen level. Biopsies performed in such patients may vary, ranging from poorly differentiated carcinomas to mixed adenocarcinoma-small cell carcinomas to pure small cell carcinomas. These aggressive tumors often demonstrate low or absent AR protein expression and, in some cases, express markers of neuroendocrine differentiation. Because tumor morphology is not always predicted by clinical behavior, the terms "anaplastic prostate cancer" or "neuroendocrine prostate cancer" have been used descriptively to describe these rapidly growing clinical features. Patients meeting clinical criteria of anaplastic prostate cancer have been shown to predict for poor prognosis, and these patients may be considered for platinum-based chemotherapy treatment regimens. Therefore, understanding variants within the spectrum of advanced prostate cancer has important diagnostic and treatment implications.

A patient tumor-derived orthotopic xenograft mouse model replicating the group 3 supratentorial primitive neuroectodermal tumor in children

BACKGROUND

Supratentorial primitive neuroectodermal tumor (sPNET) is a malignant brain tumor with poor prognosis. New model systems that replicate sPNET's molecular subtype(s) and maintain cancer stem cell (CSC) pool are needed.

METHODS

A fresh surgical specimen of a pediatric sPNET was directly injected into the right cerebrum of Rag2/SCID mice. The xenograft tumors were serially sub-transplanted in mouse brains, characterized histopathologically, and subclassified into molecular subtype through qRT-PCR and immunohistochemical analysis. CSCs were identified through flow cytometric profiling of putative CSC markers (CD133, CD15, CD24, CD44, and CD117), functional examination of neurosphere forming efficiency in vitro, and tumor formation capacity in vivo. To establish a neurosphere line, neurospheres were propagated in serum-free medium.

RESULTS

Formation of intracerebral xenograft tumors was confirmed in 4 of the 5 mice injected with the patient tumor. These xenograft tumors were sub-transplanted in vivo 5 times. They replicated the histopathological features of the original patient tumor and expressed the molecular markers (TWIST1 and FOXJ1) of group 3 sPNET. CD133(+) and CD15(+) cells were found to have strong neurosphere-forming efficiency in vitro and potent tumor-forming capacity (with as few as 100 cells) in vivo. A neurosphere line BXD-2664PNET-NS was established that preserved stem cell features and expressed group 3 markers.

CONCLUSION

We have established a group 3 sPNET xenograft mouse model (IC-2664PNET) with matching neurosphere line (BXD-2664PNET-NS) and identified CD133(+) and CD15(+) cells as the major CSC subpopulations. This novel model system should facilitate biological studies and preclinical drug screenings for childhood sPNET.

Rb loss is characteristic of prostatic small cell neuroendocrine carcinoma

PURPOSE

Small cell neuroendocrine carcinoma of the prostate is likely to become increasingly common with recent advances in pharmacologic androgen suppression. Thus, developing molecular markers of small cell differentiation in prostate cancer will be important to guide the diagnosis and therapy of this aggressive tumor.

EXPERIMENTAL DESIGN

We examined the status of RB1, TP53, and PTEN in prostatic small cell and acinar carcinomas via immunohistochemistry (IHC), copy-number alteration analysis, and sequencing of formalin-fixed paraffin-embedded specimens.

RESULTS

We found retinoblastoma (Rb) protein loss in 90% of small cell carcinoma cases (26 of 29) with RB1 allelic loss in 85% of cases (11 of 13). Of acinar tumors occurring concurrently with prostatic small cell carcinoma, 43% (3 of 7) showed Rb protein loss. In contrast, only 7% of primary high-grade acinar carcinomas (10 of 150), 11% of primary acinar carcinomas with neuroendocrine differentiation (4 of 35), and 15% of metastatic castrate-resistant acinar carcinomas (2 of 13) showed Rb protein loss. Loss of PTEN protein was seen in 63% of small cell carcinomas (17 of 27), with 38% (5 of 13) showing allelic loss. By IHC, accumulation of p53 was observed in 56% of small cell carcinomas (14 of 25), with 60% of cases (6 of 10) showing TP53 mutation.

CONCLUSIONS

Loss of RB1 by deletion is a common event in prostatic small cell carcinoma and can be detected by a validated IHC assay. As Rb protein loss rarely occurs in high-grade acinar tumors, these data suggest that Rb loss is a critical event in the development of small cell carcinomas and may be a useful diagnostic and potential therapeutic target.

CD44 as a molecular marker to screen cancer stem cells in hypopharyngeal cancer

CONCLUSIONS

The CD44(+) cells have a stronger proliferative capacity and higher tumorigenic potential than the CD44(-) cells, which suggests that the cancer stem cells of hypopharyngeal cancer may exist in the CD44(+) tumor cell population. Therefore, we propose that CD44 is an important biological marker to screen cancer stem cells of hypopharyngeal cancer.

OBJECTIVES

To study the significance of CD44 as a molecular marker for screening cancer stem cells in hypopharyngeal cancer.

METHODS

The CD44 expression levels in the hypopharyngeal cancer cell line FaDu were analyzed using flow cytometry. To investigate the biological significance of the CD44(+) population, we sorted the CD44(+) and CD44(-) cell populations by using magnetic-associated cell sorting (MACS) technology. After the separation, the purity of the CD44(+) cells was determined using flow cytometry. The MTT method was used to detect the different proliferation capabilities of the CD44(+) and CD44(-) cells in vitro. The tumorigenicity of the CD44(+) and CD44(-) cells was determined by injecting CD44(+) or CD44(-) cells (1 × 10(6) and 1 × 10(5)) into the body of NOD/SCID mice.

RESULTS

Some (21.1 ± 1.56)% of the hypopharyngeal cancer cell line FaDu cells expressed CD44. The CD44(+) population was efficiently sorted by MACS, and after separation, the purity of the CD44(+) cells was (99.4 ± 0.29)%. The MTT assay indicated that the sorted CD44(+) cells had a stronger proliferative capacity than the CD44(-) cells. The tumorigenicity study showed that all the mice injected with 1 × 10(6) CD44(+) cells developed tumors (8/8), half the mice injected with 1 × 10(6) CD44(-) cells developed tumors (4/8), 1 of the 8 mice injected with 1 × 10(5) CD44(+) cells developed tumors (12.5%), but none of the mice injected with 1 × 10(5) CD44(-) cells developed any tumors (0/8). At the same concentration, the difference in tumorigenic rates between the CD44(+) and CD44(-) groups was statistically significant (Fisher's exact test, p < 0.05). Furthermore, the CD44(+) group had a shorter incubation period than the CD44(-) group. In addition, the average tumor volume of the CD44(+) group was (2017.81 ± 538.50) mm(3); however, the average tumor volume of the CD44(-) group was (1153.25 ± 503.18) mm(3). The difference was statistically significant (t = 2.67, p < 0.05).

CK5, CK5/6, and double-stains CK7/CK5 and p53/CK5 discriminate in situ vs invasive urothelial cancer in the prostate

For primary bladder tumors, distinguishing urothelial carcinoma (UC) invading the fibromuscular stroma of the prostate (pT4a) from in situ UC involving prostatic ducts can be difficult. Immunohistochemical markers (cytokeratin [CK]5/6, CK5, CK7, CK20, p53, p63, high-molecular-weight keratin [HMWK], androgen receptor, prostate-specific antigen [PSA], prostate specific acid phosphatase [PSAP], laminin, CD44s, CD141) were assessed for their usefulness in determining depth of UC invasion in the prostate. In cystoprostatectomy specimens containing in situ UC in prostatic ducts, both CK5/6 and CK5 clearly differentiated prostatic basal cells from in situ UC. The remaining markers were not effective in determining depth of tumor invasion. Double-stain combinations CK7/CK5 and p53/CK5 were performed and robustly color contrasted in situ tumor from surrounding basal cells. The use of CK5/6, CK5, CK7/CK5, or p53/CK5 is recommended to assist in determining the depth of UC invasion in the prostate when histologic findings are equivocal.

Prognostic significance of neuroendocrine differentiation in prostate adenocarcinoma

Much progress has been made toward an understanding of the development and progression of prostate cancer (PC) and the factors that drive the development of androgen independence. Neuroendocrine (NE) cells may provide an intriguing link between NE cell differentiation (NED) and tumor progression in PC. NED in PC generally confers a more aggressive clinical behavior and less favorable prognosis than conventional PC. In this article, we review the known functions of NE cells in PC and discuss the current knowledge on stimulation of cancer proliferation, invasion, apoptosis resistance, serum and immunohistochemical markers, and the prognostic significance of NED in human PC.

Prostatic carcinomas with neuroendocrine differentiation diagnosed in needle biopsies, a morphologic study of 7 cases among 465 sequential biopsies in a tertiary cancer center

PURPOSE

Neuroendocrine carcinomas (NEC) of the prostate are rare, with only a few series hitherto reported. The objective of this study was to assess in a single institution the clinical and morphologic characteristics of neuroendocrine carcinomas diagnosed in needle core biopsies.

MATERIALS AND METHODS

The current study analyses seven cases diagnosed in needle biopsies at a large tertiary regional cancer center from Northeastern Brazil. Two pathologists reviewed specimens retrospectively, and demographic and morphologic characteristics were compared to 458 acinar tumors diagnosed in the same period.

RESULTS

There were five small cell carcinomas and two low-grade neuroendocrine carcinomas (carcinoid). NEC were associated with an acinar component in 5/7 cases and the Gleason score of the acinar component was always > 6. The number of cores involved in prostates with NEC was greater (65% compared to 24% of acinar tumors, p < 0.05). The mean PSA at diagnosis was 417.7 (range 5.7-1593, SD 218.3), compared to 100.5 (p = 0.1) of acinar tumors (range 0.3-8545, SD 22.7). Prostates harboring NEC were bigger (p < 0.001, mean volume 240 mL vs. 53 mL of acinar tumors). Treatment of NEC included palliative surgery, chemotherapy, and hormonal therapy.

CONCLUSIONS

NEC of the prostate is rare and often associated with a high-grade acinar component. Prostates with NEC tend to be larger and involve a greater number of cores than acinar tumors. PSA at diagnosis does not seem to predict the presence of NE tumors in needle biopsy.

PC3 is a cell line characteristic of prostatic small cell carcinoma

BACKGROUND

The majority of the prostatic cancers are adenocarcinomas characterized by glandular formation and the expression of luminal differentiation markers androgen receptor (AR) and prostate-specific antigen (PSA). Most adenocarcinomas are indolent and androgen-dependent. Hormonal therapy that inhibits AR signaling produces symptomatic relief in patients with advanced and metastatic adenocarcinomas. Prostatic small cell neuroendocrine carcinoma (SCNC) is a variant form of prostate cancer (PC). In contrast to adenocarcinoma, the tumor cells of SCNC do not form glands and are negative for AR and PSA. SCNC is extremely aggressive and does not respond to hormonal therapy. The purpose of this study was to compare the important and relevant features of two most commonly used PC cell lines, LNCaP and PC3, with prostatic adenocarcinoma and SCNC.

METHODS

Xenograft tumors of LNCaP and PC3 were prepared and compared with human prostatic adenocarcinoma and SCNC for the expression of key signaling molecules by immunohistochemistry and Western blot analysis.

RESULTS

LNCaP cells express AR and PSA and their growth is inhibited by androgen withdrawal, similar to human prostatic adenocarcinoma. PC3 cells do not express AR and PSA and their proliferation is independent of androgen, similar to SCNC. Adenocarcinoma cells and LNCaP cells are negative for neuroendocrine markers and stem cell-associated marker CD44 while SCNC and PC3 cells are positive. LNCaP cells have identical cytokeratin profiles to adenocarcinoma while PC3 cells have cytokeratin profiles similar to SCNC.

CONCLUSION

LNCaP cells share common features with adenocarcinoma while PC3 cells are characteristic of SCNC.

Review of small cell carcinomas of the prostate

Small cell carcinoma of the prostate is a rare neoplasm, with only a few series hitherto reported. A little less than half of the cases are associated with conventional acinar adenocarcinoma, which are usually high grade. Although consensus has not been reached, the majority of patients with small cell neuroendocrine carcinoma of the prostate have advanced disease at diagnosis and disproportionally low PSA levels compared to patients with conventional acinar adenocarcinoma. Treatment consists mainly of chemotherapy associated with surgery. Radiation therapy is reserved for selected cases. This study reviews the most up-to-date information on small cell carcinomas of the prostate.

ERG-TMPRSS2 rearrangement is shared by concurrent prostatic adenocarcinoma and prostatic small cell carcinoma and absent in small cell carcinoma of the urinary bladder: evidence supporting monoclonal origin

Prostatic carcinoma is a heterogeneous disease with frequent multifocality and variability in morphology. Particularly, prostatic small cell carcinoma is a rare variant with aggressive behavior. Distinction between small cell carcinoma of the prostate and urinary bladder may be challenging, especially in small biopsy specimens without associated prostatic adenocarcinoma or urothelial carcinoma. Recently, gene fusions between ETS genes, particularly ETS-related gene (ERG), and transmembrane protease, serine 2 (TMPRSS2) have been identified as a frequent event in prostate cancer. Thus, molecular methods may be helpful in determining the primary site of small cell carcinoma. Thirty cases of prostatic small cell carcinoma from the authors' archives were studied, among which 13 had concurrent prostatic adenocarcinoma. Tricolor fluorescence in situ hybridization (FISH) was performed on formalin-fixed paraffin-embedded tissue sections with a probe cocktail for 3'/5' ERG and TMPRSS2. Cases of small cell carcinoma of the bladder and conventional prostatic adenocarcinoma (25 each) were also tested as controls. ERG gene alterations were found only in prostate malignancies and not in benign prostatic tissue or bladder small cell carcinoma. TMPRSS2-ERG gene fusion was found in 47% (14/30) of prostatic small cell carcinoma. Of cases with concurrent prostatic adenocarcinoma, 85% (11/13) had identical findings in both components. In 20% of rearranged cases, the ERG abnormality was associated with 5' ERG deletion. In 17% (5/30) of cases, gain of the 21q22 locus was present. Two cases showed discordant aberrations in the small cell carcinoma and adenocarcinoma, one with deletion of 5' ERG and one with gain of chromosome 21q, both in only the adenocarcinoma component. Small cell carcinoma of the prostate demonstrates TMPRSS2-ERG rearrangement with comparable frequency to prostatic adenocarcinoma. In cases with concurrent adenocarcinoma and small cell carcinoma, the majority showed identical abnormalities in both components, indicating a likely common clonal origin. Discordant alterations were present in rare cases, suggesting that acquisition of additional genetic changes in multifocal tumors may be responsible for disease progression to a more aggressive phenotype. TMPRSS2-ERG fusion is absent in bladder small cell carcinoma, supporting the utility of FISH in distinguishing prostate from bladder primary tumors and identifying metastatic small cell carcinoma of unknown origin.

Expression analysis of putative stem cell markers in human benign and malignant prostate

BACKGROUND

Stem cells were suggested to be present in human prostate cancer as a small population of distinct cells, which may contribute to carcinogenesis, tumor recurrence, and chemoresistance. To identify potential prostatic stem cells, we analyzed the expression of several potential stem cell markers in benign prostate and prostatic adenocarcinoma.

METHODS

CD44, CD133, Oct4, SOX2, and EZH2 expression was detected by immunohistochemical (IHC) staining using tissue microarray assays (TMA) composed of benign (non-neoplastic) prostatic tissue, high grade prostatic intraepithelial neoplasia (HGPIN), and prostatic adenocarcinoma. Positive staining was defined as 1+ (<10%), 2+ (10-50%), or 3+ (>50%).

RESULTS

We found CD44 staining in 97% and 72% of benign + HGPIN and malignant lesions, respectively. CD133 staining was detected in a small fraction (4 of 67) of prostate carcinomas. We found that Oct4 nuclear expression was strongly associated with benign lesions and HGPIN but not prostate cancer (P < 0.05). In most cases, nuclear expression of EZH2 and SOX2 was detected in less than 10% of cells in non-neoplastic prostate glands, HGPINs or prostate adenocarcinomas. Moreover, 27 of 33 SOX2 1+ prostate cancers were also EZH2 1+, whereas all 33 of these cases were CD44+.

CONCLUSIONS

Expression of CD44 and Oct4 identified large populations of benign and malignant cells in the prostate, which did not fit the definition of stem cells as a small fraction of the total cell population. Our results suggest that combined expression of embryonic stem cell markers EZH2 and SOX2 might identify potential cancer stem cells as a minor (<10%) subgroup in CD44+ prostatic adenocarcinoma.

TMPRSS2-ERG gene fusion in small cell carcinoma of the prostate

Recent studies have shown that most prostate cancers carry the TMPRSS2-ERG gene fusion. Here we evaluated the TMPRSS2-ERG gene fusion in small cell carcinoma of the prostate (n = 12) in comparison with small cell carcinoma of the urinary bladder (n = 12) and lung (n = 11). Fluorescence in situ hybridization demonstrated rearrangement of the ERG gene in 8 cases of prostatic small cell carcinoma (67%), and the rearrangement was associated with deletion of the 5' ERG gene in 7 cases, but rearrangement of the ERG gene was not present in any small cell carcinoma of the urinary bladder or lung. Next we evaluated the TMPRSS2-ERG gene fusion in nude mouse xenografts that were derived from 2 prostatic small cell carcinomas carrying the TMPRSS2-ERG gene fusion. Two transcripts encoded by the TMPRSS2-ERG gene fusion were detected by reverse transcriptase polymerase chain reaction, and DNA sequencing demonstrated that the 2 transcripts were composed of fusions of exon 1 of the TMPRSS2 gene to exon 4 or 5 of the ERG gene. Our study demonstrates the specific presence of TMPRSS2-ERG gene fusion in prostatic small cell carcinoma, which may be helpful in distinguishing small cell carcinoma of prostatic origin from nonprostatic origins. The high prevalence of the TMPRSS2-ERG gene fusion in prostatic small cell carcinoma as well as adenocarcinoma implies that small cell carcinoma may share a common pathogenic pathway with adenocarcinoma in the prostate.

Novel therapies against aggressive and recurrent epithelial cancers by molecular targeting tumor- and metastasis-initiating cells and their progenies

A growing body of experimental evidence has revealed that the highly tumorigenic cancer stem/progenitor cells endowed with stem cell-like properties might be responsible for initiation and progression of numerous aggressive epithelial cancers into locally invasive, metastatic and incurable disease states. The malignant transformation of tissue-resident adult stem/progenitor cells or their progenies into tumorigenic and migrating cancer stem/progenitor cells and their resistance to current cancer therapies have been associated with their high expression levels of specific oncogenic products and drug resistance-associated molecules. In this regard, we describe the tumorigenic cascades that are frequently activated in cancer stem/progenitor cells versus their differentiated progenies during the early and late stages of the epithelial cancer progression. The emphasis is on the growth factor signaling pathways involved in the malignant behavior of prostate and pancreatic cancer stem/progenitor cells and their progenies. Of clinical interest, the potential molecular therapeutic targets to eradicate the tumor- and metastasis-initiating cells and their progenies and develop new effective combination therapies against locally advanced and metastatic epithelial cancers are also described.