A Novel Primary Cilium-Mediated Mechanism Through which Osteocytes Regulate Metastatic Behavior of Both Breast and Prostate Cancer Cells

Bone metastases are a common cause of suffering in breast and prostate cancer patients, however, the interaction between bone cells and cancer cells is poorly understood. Using a series of co-culture, conditioned media, human cancer spheroid, and organ-on-a-chip experiments, this study reveals that osteocytes suppress cancer cell proliferation and increase migration via tumor necrosis factor alpha (TNF-α) secretion. This action is regulated by osteocyte primary cilia and associated intraflagellar transport protein 88 (IFT88). Furthermore, it shows that cancer cells block this mechanism by secreting transforming growth factor beta (TGF-β), which disrupts osteocyte cilia and IFT88 gene expression. This bi-directional crosstalk signaling between osteocytes and cancer cells is common to both breast and prostate cancer. This study also proposes that osteocyte inhibition of cancer cell proliferation decreases as cancer cells increase, producing more TGF-β. Hence, a positive feedback loop develops accelerating metastatic tumor growth. These findings demonstrate the importance of cancer cell-osteocyte signaling in regulating breast and prostate bone metastases and support the development of therapies targeting this pathway.

28S rRNA-Derived Fragments Represent an Independent Molecular Predictor of Short-Term Relapse in Prostate Cancer

Prostate cancer (PCa) is a global health concern, being a leading cause of cancer-related mortality among males. Early detection and accurate prognosis are crucial for effective management. This study delves into the diagnostic and prognostic potential of 28S rRNA-derived fragments (rRFs) in PCa. Total RNA extracted from 89 PCa and 53 benign prostate hyperplasia (BPH) tissue specimens. After 3'-end polyadenylation, we performed reverse transcription to create first-strand cDNA. Using an in-house quantitative real-time PCR (qPCR) assay, we quantified 28S rRF levels. Post-treatment biochemical relapse served as the clinical endpoint event for survival analysis, which we validated internally through bootstrap analysis. Our results revealed downregulated 28S rRF levels in PCa compared to BPH patients. Additionally, we observed a significant positive correlation between 28S rRF levels and higher Gleason scores and tumor stages. Furthermore, PCa patients with elevated 28S rRF expression had a significantly higher risk of post-treatment disease relapse independently of clinicopathological data. In conclusion, our study demonstrates, for the first time, the prognostic value of 28S rRF in prostate adenocarcinoma. Elevated 28S rRF levels independently predict short-term PCa relapse and enhance risk stratification. This establishes 28S rRF as a potential novel molecular marker for PCa prognosis.

Synthesis and In Vitro Evaluation as Potential Anticancer and Antioxidant Agents of Diphenylamine-Pyrrolidin-2-one-Hydrazone Derivatives

The title compounds were synthesized by the reaction of 5-oxo-1-(4-(phenylamino)phenyl)pyrrolidine-3-carbohydrazide with various aldehydes bearing aromatic and heterocyclic moieties and acetophenones, and their cytotoxicity was tested via MTT assay against human triple-negative breast cancer MDA-MB-231, human melanoma IGR39, human pancreatic carcinoma Panc-1, and prostate cancer cell line PPC-1. Furthermore, the selectivity of compounds towards cancer cells compared to fibroblasts was also investigated. Four compounds were identified as the most promising anticancer agents out of a series of pyrrolidinone-hydrazone derivatives bearing a diphenylamine moiety. These compounds were most selective against the prostate cancer cell line PPC-1 and the melanoma cell lines IGR39, with EC50 values in the range of 2.5-20.2 µM against these cell lines. In general, the compounds were less active against triple-negative breast cancer MDA-MB-231 cell line, and none of them showed an inhibitory effect on the migration of these cells. In the 'wound healing' assay, N'-((5-nitrothiophen-2-yl)methylene)-5-oxo-1-(4-(phenylamino)phenyl)pyrrolidine-3-carbohydrazide was identified as the most promising derivative that could be further developed as an antimetastatic agent. N'-(5-chloro- and N'-(3,4-dichlorobenzylidene)-5-oxo-1-(4-(phenylamino)phenyl)pyrrolidine-3-carbohydrazides most efficiently reduced the cell viability in IGR39 cell spheroids, while there was no effect of the investigated pyrrolidinone-hydrazone derivatives on PPC-1 3D cell cultures. Antioxidant activity determined via FRAP assay of N'-(1-(4-aminophenyl)ethylidene)-5-oxo-1-(4-(phenylamino)phenyl)pyrrolidine-3-carbohydrazide was 1.2 times higher than that of protocatechuic acid.

Identification of a novel recurrent EEF2 gene amplification in familial prostate tumors

Recurrent tumor copy number variations (CNVs) in prostate cancer (PrCa) have predominantly been discovered in sporadic tumor cohorts. Here, we examined familial prostate tumors for novel CNVs as prior studies suggest these harbor distinct CNVs. Array comparative genomic hybridization of 12 tumors from an Australian PrCa family, PcTas9, highlighted multiple recurrent CNVs, including amplification of EEF2 (19p13.3) in 100% of tumors. The EEF2 CNV was examined in a further 26 familial and seven sporadic tumors from the Australian cohort and in 494 tumors unselected for family history from The Cancer Genome Atlas (TCGA). EEF2 overexpression was observed in seven PcTas9 tumors, in addition to seven other predominantly familial tumors (n_total  = 34%). EEF2 amplification was only observed in 1.4% of TCGA tumors, however 7.5% harbored an EEF2 deletion. Analysis of genes co-expressed with EEF2 revealed significant upregulation of two genes, ZNF74 and ADSL, and downregulation of PLSCR1 in both EEF2 amplified familial tumors and EEF2 deleted TCGA tumors. Furthermore, in TCGA tumors, EEF2 amplification and deletion were significantly associated with a higher Gleason score. In summary, we identified a novel PrCa CNV that was predominantly amplified in familial tumors and deleted in unselected tumors. Our results provide further evidence that familial tumors harbor distinct CNVs, potentially due to an inherited predisposition, but also suggest that regardless of how EEF2 is dysregulated, a similar set of genes involved in key cancer pathways are impacted. Given the current lack of gene-based biomarkers and clinical targets in PrCa, further investigation of EEF2 is warranted.

Prostate health index (PHI) as a reliable biomarker for prostate cancer: a systematic review and meta-analysis

OBJECTIVES

Prostate cancer (PCa) represents the second most common solid cancer in men worldwide. In the last decades, the prostate health index (PHI) emerged as a reliable biomarker for detecting PCa and differentiating between non-aggressive and aggressive forms. However, before introducing it in clinical practice, more evidence is required. Thus, we performed a systematic review and meta-analysis for assessing the diagnostic performance of PHI for PCa and for detecting clinically significant PCa (csPCa).

METHODS

Relevant publications were identified by a systematic literature search on PubMed and Web of Science from inception to January 11, 2022.

RESULTS

Sixty studies, including 14,255 individuals, met the inclusion criteria for our meta-analysis. The pooled sensitivity and specificity of PHI for PCa detection was 0.791 (95%CI 0.739-0.834) and 0.625 (95%CI 0.560-0.686), respectively. The pooled sensitivity and specificity of PHI for csPCa detection was 0.874 (95%CI 0.803-0.923) and 0.569 (95%CI 0.458-0.674), respectively. Additionally, the diagnostic odds ratio was 6.302 and 9.206, respectively, for PCa and csPCa detection, suggesting moderate to good effectiveness of PHI as a diagnostic test.

CONCLUSIONS

PHI has a high accuracy for detecting PCa and discriminating between aggressive and non-aggressive PCa. Thus, it could be useful as a biomarker in predicting patients harbouring more aggressive cancer and guiding biopsy decisions.

Bone Marrow-Derived Mesenchymal Stem Cells Migrate toward Hormone-Insensitive Prostate Tumor Cells Expressing TGF-β via N-Cadherin

The prostate tumor microenvironment plays important roles in the metastasis and hormone-insensitive re-growth of tumor cells. Bone marrow-derived mesenchymal stem cells (BM-MSCs) are recruited into prostate tumors to facilitate tumor microenvironment formation. However, the specific intrinsic molecules mediating BM-MSCs’ migration to prostate tumors are unknown. BM-MSCs’ migration toward a conditioned medium (CM) of hormone-insensitive (PC3 and DU145) or hormone-sensitive (LNCaP) prostate tumor cells was investigated using a three-dimensional cell migration assay and a transwell migration assay. PC3 and DU145 expressed transforming growth factor-β (TGF-β), but LNCaP did not. Regardless of TGF-β expression, BM-MSCs migrated toward the CM of PC3, DU145, or LNCaP. The CM of PC3 or DU145 expressing TGF-β increased the phosphorylation of Smad2/3 in BM-MSCs. Inactivation of TGF-β signaling in BM-MSCs using TGF-β type 1 receptor (TGFBR1) inhibitors, SB505124, or SB431542 did not allow BM-MSCs to migrate toward the CM. The CM of PC3 or DU145 enhanced N-cadherin expression on BM-MSCs, but the LNCaP CM did not. SB505124, SB431542, and TGFBR1 knockdown prevented an increase in N-cadherin expression. N-cadherin knockdown inhibited the collective migration of BM-MSCs toward the PC3 CM. We identified N-cadherin as a mediator of BM-MSCs’ migration toward hormone-insensitive prostate tumor cells expressing TGF-β and introduced a novel strategy for controlling and re-engineering the prostate tumor microenvironment.

Prognostic Value of Genes and Immune Infiltration in Prostate Tumor Microenvironment

Background

Prostate cancer (PCa) is one of the most common cancers and the fifth leading cause of cancer-related death in men. Immune responses in the tumor microenvironment are hypothesized to be related to the prognosis of PCa patients; however, no studies are available to confirm the same. In this study, we aimed to explore the potential link between these two factors and identify new biomarkers to estimate the survival rate of PCa patients.

Methods

A total of 490 cases were obtained from The Cancer Genome Atlas (TCGA) database. The gene expression data were analyzed by the ESTIMATE algorithm to evaluate the immune and stromal scores. The survival rate was calculated according to the case-specific clinical data. Enrichment analysis was performed to discover the main biological processes and signaling pathways of immune responses. We further identified and analyzed hub genes in the protein-protein interaction (PPI) network and evaluated their prognostic values.

Results

Immune score significantly correlated with immune cell infiltration and overall survival of PCa patients. The genes CXCR4 and GPR183, identified as hub genes in the PPI network, correlated with immune cell infiltration and prognosis of PCa patients.

Conclusion

CXCR4 and GPR183 participate in immune cell infiltration and function in PCa patients. The immune score, as well as the expression of CXCR4 and GPR183 in prostate cancer tissues, could be potential indexes for the prognosis of prostate cancer.

MINDIN secretion by prostate tumors induces premetastatic changes in bone via β-catenin

Bone metastases are common in advanced prostate cancer patients, but mechanisms by which specific pro-metastatic skeletal niches are formed before tumor cell homing are unclear. We aimed to analyze the effects of proteins secreted by primary prostate tumors on the bone microenvironment before the settlement and propagation of metastases. Here, using an in vivo pre-metastatic prostate cancer model based on the implantation of prostate adenocarcinoma TRAMP-C1 cells in immunocompetent C57BL/6 mice, we identify MINDIN as a prostate tumor secreted protein that induces bone microstructural and bone remodeling gene expression changes before tumor cell homing. Associated with these changes, increased tumor cell adhesion to the endosteum ex vivo and to osteoblasts in vitro was observed. Furthermore, MINDIN promoted osteoblast proliferation and mineralization and monocyte expression of osteoclast markers. β-catenin signaling pathway revealed to mediate MINDIN actions on osteoblast gene expression but failed to affect MINDIN-induced adhesion to prostate tumor cells or monocyte differentiation to osteoclasts. Our study evidences that MINDIN secretion by primary prostate tumors creates a favorable bone environment for tumor cell homing before metastatic spread.

PD-L1 instead of PD-1 status is associated with the clinical features in human primary prostate tumors

Immunotherapy targeting programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) has shown efficacy in a variety of solid tumors. However, prostate cancer has often been a non-responder to anti-PD-1/PD-L1 therapies. The objective of this study was to determine PD-1 and PD-L1 expression status and its correlation with clinical features of the patients. A total of 279 patients who underwent radical prostatectomy for prostate cancer were included in this study. PD-1 and PD-L1 expression in primary prostate tumors was detected using immunohistochemical staining. Analyses were made between PD-1/PD-L1 status and patients' age, ethnicity, body mass index (BMI), diabetes mellitus, tumor stage, lymph node metastasis, prostate-specific antigen (PSA), Gleason score, grade group, and survival. We found that 6.5 (standard deviation 14.3; range 0-161.6) tumor-infiltrating lymphocytes per high power field were positive for PD-1 staining and 50/279 (17.9%) tumors were positive for PD-L1 staining. PD-L1-positive tumors had significantly more PD-1-positive lymphocytes than PD-L1-negative tumors. The number of PD-1-positive lymphocytes was not correlated with any clinical features except that patients with diabetes had significantly less PD-1-positive lymphocytes than patients without diabetes. In contrast, more PD-L1-positive tumors were found in older patients (≥ 65 years), obese patients (BMI ≥ 30), and patients with advanced tumor stage, lymph node metastasis, and high Gleason score. Neither PD-1 nor PD-L1 status was correlated with ethnicity, PSA, or survival. Our findings suggest that PD-L1 instead of PD-1 status is associated with the clinical features in human primary prostate tumors.

Examining correlations of oxygen sensitive MRI (BOLD/TOLD) with [18F]FMISO PET in rat prostate tumors

Hypoxia is regarded as a potential prognostic biomarker for tumor aggressiveness, progression, and response to therapy. The radiotracer ¹⁸F-fluoromisonidazole ([¹⁸F]FMISO) has been used with positron emission tomography (PET) to reveal tumor hypoxia. Meanwhile, blood oxygen level dependent (BOLD) MRI and tissue oxygen level dependent (TOLD) MRI offer insight into oxygenation based on endogenous signals without the need for radiolabels. Here, we compared BOLD and TOLD MRI with [¹⁸F]FMISO uptake using Dunning prostate R3327-AT1 tumor bearing rats. BOLD and TOLD MRI were acquired with respect to an oxygen gas breathing challenge. The following day, dynamic PET was performed up to 90 minutes following IV injection of [¹⁸F]FMISO. Tumors showed distinct heterogeneity based on each technique. Correlations were observed between magnitude of mean BOLD or TOLD MRI signal responses to oxygen-breathing challenge and initial distribution of [¹⁸F]FMISO. Correlations were observed for whole tumor as well on a regional basis with stronger correlations in the well perfused tumor periphery indicating the strong influence of perfused vasculature. After 90 minutes most correlations with signal intensity became quite weak, but correlations were observed between hypoxic fraction based on FMISO and fractions of tumor showing BOLD or TOLD response in a subset of tumors. This emphasizes the importance of considering regional heterogeneity and responsive fractions, as opposed to simple magnitudes of responses. Although the data represent a small cohort of tumors they present direct correlations between oxygen sensitive MRI and PET hypoxia reporter agents in the same tumors, indicating the potential utility of further investigations.

[Clinicopathological characterization of non-Hodgkin lymphoma of the prostate]

OBJECTIVE

To study the clinicopathological characteristics of non-Hodgkin lymphoma (NHL) of the prostate.

METHODS

We collected the clinical data on 6 cases of NHL of the prostate pathologically confirmed between 2001 and 2017. The patients were aged 49－76 (median 62) years old, with the main clinical manifestations of painless swelling of the prostate and lower urinary tract obstruction. We analyzed the clinical features and the results of histological detection, immunohistochemical staining and B-cell gene rearrangement assay, and explored the clinicopathological characteristics and differential diagnosis of the disease based on the relevant literature.

RESULTS

Histological detection revealed diffuse large B-cell lymphoma (DLBCL) in 4 cases (66.7%), B-lymphoblastic lymphoma (B-LBL) in 1 (16.7%), and Burkitt lymphoma (BL) in another (16.7%). DLBCL was histologically characterized by diffuse oval or round medium-to-large-sized lyphoid cells with an infiltrative growth pattern, B-LBL by monotonous small-to-medium-sized lymphoid cells with prominet mitosis and apoptosis, and BL by diffuse and monotonous medium-sized neoplastic cells with round or oval nuclei, an infiltrative growth pattern, scanty cytoplasm and visible mitosis. One of the DLBCL patients received 5 doses of R-CHOP chemotherapy and has been followed up to the present time, while the other 3 were lost to follow-up; the B-LBL patient died at 1 month after diagnosis; and the BL patient gave up treatment.

CONCLUSIONS

Non-Hodgkin's lymphoma of the prostate mostly presents as diffuse large B-cell lymphoma, and its diagnosis depends on immunohistochemistry and related molecular detection as well as its clinical and histopathological manifestations.

Biodistribution and Pharmacokinetic Evaluations of a Novel Taxoid DHA-SBT-1214 in an Oil-in-Water Nanoemulsion Formulation in Naïve and Tumor-Bearing Mice

PURPOSE

The main purpose of this study was to formulate an oil-in-water nanoemulsion of a next generation taxoid DHA-SBT-1214 and evaluate its biodistribution and pharmacokinetics.

METHODS

DHA-SBT-1214 was encapsulated in a fish oil containing nanoemulsion using a high pressure homogenization method. Following morphological characterization of the nanoemulsions, qualitative and quantitative biodistribution was evaluated in naïve and cancer stem cell-enriched PPT-2 human prostate tumor bearing mice.

RESULTS

DHA-SBT-1214 was successfully encapsulated up to 20 mg/ml in the nanoemulsion formulation and had an average oil droplet size of 200 nm. Using a DiR near infra-red dye encapsulated nanoemulsion, we have shown the delivery of nanoemulsion to mouse tumor region. By quantitative analysis, DHA-SBT-1214 encapsulated nanoemulsion demonstrated improved pharmacokinetic properties in plasma and different tissues as compared to its solution form. Furthermore, the nanoemulsions were stable and had slower in vitro drug release compared to its solution form.

CONCLUSIONS

The results from this study demonstrated effective encapsulation of the drug in a nanoemulsion and this nanoemulsion showed sustained plasma levels and enhanced tumor delivery relative to the solution form.

HDAC inhibitor PAC-320 induces G2/M cell cycle arrest and apoptosis in human prostate cancer

HDAC inhibitors (HDACis) have been demonstrated with profound antiproliferative activities in various tumor types. Previously, we screened several polyoxometalate HDACis based on our p21 luciferase promoter system and demonstrated that such HDACis have antitumor activity. Here, we further investigate the antitumor mechanism of PAC-320, a compound among the polyoxometalates, in human prostate cancer. We demonstrate that PAC-320 is a broad-spectrum HDACi and could inhibit growth of prostate cancer cells in vitro and in vivo. Furthermore, we find that PAC-320 induces cell cycle arrest at G2/M phase and apoptosis. Mechanically, PAC-320 induced cell cycle arrest is associated with an increase of p21 and decrease of cyclin A and cyclin B1, while PAC-320 induced apoptosis is mediated through mitochondria apoptotic pathway and is closely associated with increase of BH3-only proteins Noxa and Hrk. Meanwhile, we demonstrate that p38 MAPK pathway is involved in PAC-320 induced antiproliferative activities in prostate cancer. Taken together, our data indicates that PAC-320 has potent prostate cancer inhibitory activity in vitro and in vivo, which is mediated by G2/M cell cycle arrest and apoptosis.

Somatostatin receptor subtype 1 as a potential diagnostic marker and therapeutic target in prostate cancer

BACKGROUND

Prostate cancer (PCa) is a highly prevalent neoplasia that is strongly influenced by the endocrine system. Somatostatin (SST) and its five receptors (sst1-5 encoded by SSTR1-5 genes) comprise a pleiotropic system present in most endocrine-related cancers, some of which are successfully treated with SST analogs. Interestingly, it has been reported that SSTR1 is overexpressed in PCa, but its regulation, functional role, and clinical implications are still poorly known.

METHODS

PCa specimens (n = 52) from biopsies and control prostates from cystoprostatectomies (n = 12), as well as in silico databases were used to evaluate SSTR1 and miRNAs expression. In vitro studies in 22Rv1 PCa cells were implemented to explore the regulation of SSTR1/sst1 by different miRNAs, and to evaluate the consequences of SSTR1/sst1 overexpression, silencing and/or activation [with the specific BIM-23926 sst1 agonist (IPSEN)] on cell-proliferation, migration, signaling-pathways, and androgen-signaling.

RESULTS

We found that SSTR1 is overexpressed in multiple cohorts of PCa samples, as compared with normal prostate tissues, wherein it correlates with androgen receptor (AR) expression, and appears to be associated with aggressiveness (metastasis). Furthermore, our data revealed that SSTR1/sst1 expression might be regulated by specific miRNAs in PCa, including miR-24, which is downregulated in PCa samples and correlates inversely with SSTR1 expression. In vitro studies indicated that treatment with the BIM-23926 sst1 agonist, as well as SSTR1 overexpression, decreased, whereas SSTR1 silencing increased, cell-proliferation in 22Rv1 cells, likely through the regulation of PI3K/AKT-CCND3 signaling-pathway. Importantly, sst1 action was also able to modulate androgen/AR activity, and reduced PSA secretion from PCa cell lines.

CONCLUSIONS

Altogether, our results indicate that SSTR1 is overexpressed in PCa, where it can exert a relevant pathophysiological role by decreasing cell-proliferation and PSA secretion. Therefore, sst1, possibly in combination with miR-24, could be used as a novel tool to explore therapeutic targets in PCa.

Effective use of nanocarriers as drug delivery systems for the treatment of selected tumors

Nanotechnology has recently gained increased attention for its capability to effectively diagnose and treat various tumors. Nanocarriers have been used to circumvent the problems associated with conventional antitumor drug delivery systems, including their nonspecificity, severe side effects, burst release and damaging the normal cells. Nanocarriers improve the bioavailability and therapeutic efficiency of antitumor drugs, while providing preferential accumulation at the target site. A number of nanocarriers have been developed; however, only a few of them are clinically approved for the delivery of antitumor drugs for their intended actions at the targeted sites. The present review is divided into three main parts: first part presents introduction of various nanocarriers and their relevance in the delivery of anticancer drugs, second part encompasses targeting mechanisms and surface functionalization on nanocarriers and third part covers the description of selected tumors, including breast, lungs, colorectal and pancreatic tumors, and applications of relative nanocarriers in these tumors. This review increases the understanding of tumor treatment with the promising use of nanotechnology.

[Brachytherapy needle steering using intra-tissue real-time ultrasound 3d visualization]

AIM

To explore in a model experiment the capability of the developed software for 3D- ultrasound imaging of tumors in the pelvic tissue phantom to steer a brachytherapy needle using 6-axis robotic arm.

MATERIALS AND METHODS

The experiment employed a six-axis robotic arm with a device for moving the needle, a phantom with a tumor model and ultrasound scanner with biplane transducer. Controlled by the developed software, the robotic arm automatically inserted the needle in the phantom. At all stages of inserting the needle, its position in the phantom was continuously tracked using data obtained by the ultrasonic transducer.

RESULTS

The software was developed and tested for intra-tissue ultrasound imaging to steer a brachytherapy needle using US-scanner coupled with the robotic system providing 3D tumor modeling within the pelvic tissue phantom. In the course of the operation, the program corrects the existing model using current US images considering any shifting and swelling of the prostate.

CONCLUSION

The model experiment proved the operational capability of the proposed method of 3D tumor modeling within the pelvic tissue phantom and tracking needle movement in the phantom in real time using US scanner coupled with a robotic system for brachytherapy. Further development of the software, providing ultrasound image processing and automatically correcting the brachytherapy needle trajectory, will complete preclinical studies of a robotic arm and warrant clinical trials.

The stromal genome heterogeneity between breast and prostate tumors revealed by a comparative transcriptomic analysis

Stromal microenvironment increases tumor cell survival, proliferation and migration, and promotes angiogenesis. In order to provide comprehensive information on the stromal heterogeneity of diverse tumors, here we employed the microarray datasets of human invasive breast and prostate cancer-associated stromals and applied Gene Set Enrichment Analysis (GSEA) to compare the gene expression profiles between them. As a result, 8 up-regulated pathways and 73 down-regulated pathways were identified in the breast tumor stroma, while 32 up-regulated pathways and 18 down-regulated pathways were identified in the prostate tumor stroma. Only 9 pathways such as tryptophan metabolism were commonly up or down regulated, but most of them (including ABC transporters) were specific for these two tumors. Several essential tumors stromal marker genes were also significantly identified. For example, CDH3 was significantly up-regulated in the stromals of both breast and prostate tumors, however EGFR was only significantly down-regulated in the stromal of breast tumor. Our study would be helpful for future therapeutic and predictive applications in breast and prostate cancers.

The expression of glucocorticoid receptor is negatively regulated by active androgen receptor signaling in prostate tumors

The glucocorticoid and androgen receptors (GR and AR) can commonly regulate up to 50% of their target genes in prostate cancer (PCa) cells. GR expression is stimulated by castration therapy, which has been proposed to be one mechanism that compensates for AR signaling blockade and promotes castration-resistant PCa (CRPC) progression. However, whether GR functions as a driver for CRPC or a marker reflecting AR activity remains unclear. Here, we applied PCa tissue microarrays to show that GR protein levels were elevated by castration therapy, but reduced to pre-castration levels when tumors were at the CRPC stage. Using subrenal capsule xenograft models, we showed that GR expression was inversely correlated with AR and PSA expressions. GR expression levels are not associated with tumor invasion and metastasis phenotypes. In castration-resistant C4-2 xenografts expressing AR shRNA, regressing tumors induced by AR knockdown expressed higher levels of GR and lower levels of PSA than non-regressing tumors. Immunoblotting and real-time PCR assays further showed that AR knockdown or AR antagonists increased GR expression at both mRNA and protein levels. ChIP combined with DNA sequencing techniques identified a negative androgen responsive element (nARE) 160K base pairs upstream of the GR gene. Gel shift assays confirmed that AR directly interacted with the nARE and luciferase assays demonstrated that the nARE could mediate transcription repression by ligand-activated AR. In conclusion, GR expression is negatively regulated by AR signaling and may serve as a marker for AR signaling in prostate tumors.

Glycans and galectins in prostate cancer biology, angiogenesis and metastasis

Prostate cancer is the second most common cause of cancer and the sixth leading cause of cancer death among men worldwide. While localized prostate cancer can be cured, advanced and metastatic prostate cancer remains a significant therapeutic challenge. Malignant transformation is associated with important modifications of the cellular glycosylation profile, and it is postulated that these changes have a considerable relevance for tumor biology. Metastasis is a multiphasic process that encompasses angiogenesis, the spread of tumor cells and their growth at distant sites from the primary tumor location. Recognition of glycoconjugates by galectins, among other lectins, plays a fundamental role in the metastatic spread, tumor immune escape and the neovascularization process. Particularly in prostate cancer, both carbohydrates and galectins have been implicated in many cellular processes such as proliferation, apoptosis, migration and invasion. However, a limited number of studies assessed their potential implications in the induction of metastasis in prostate cancer patients or in animal models. Moreover, the role of galectin-glycan interactions in vivo still remains poorly understood; concerted effort should thus be made in order to shed some light on this question. This review summarizes current evidence on both the expression and role of glycans and galectins in prostate cancer, particularly turning our attention to the angiogenic and metastatic processes.

Ultrasound-guided intra-tumor injection of combined immunotherapy cures mice from orthotopic prostate cancer

Intra-tumor injection of immunotherapeutic agents is often the most effective, likely because of concomitant modification of tumor microenvironment. We tested an immunotherapeutic regimen consisting of CpG oligonucleotides and of adenovirus-mediated gene delivery of CCL16 chemokine directly into orthotopically implanted prostate tumors by ultrasound-guided injection, followed by systemic administration of an anti-IL-10R antibody. This combination treatment induced rapid stromal rearrangement, characterized by massive leukocyte infiltration and large areas of necrosis, a scenario that eventually led to complete tumor rejection and systemic immunity in 75 % of the treated mice. In vivo T lymphocyte depletion experiments demonstrated that the efficacy of CCL16/CpG/anti-IL-10R combination treatment relies upon CD8 T lymphocytes whereas CD4 T cells are dispensable. The results underlie the feasibility of echo-guided local immunotherapy of tumors located in visceral organs that are not easily accessible.

Paraganglioma of prostatic origin

INTRODUCTION

Paragangliomas are usually benign tumors arising from chromaffin cells located outside the adrenal gland. Prostatic paraganglioma is an unusual entity in adult patients, with only 10 cases reported in the medical literature.

CASE REPORT

A 34-year-old male with a history of chronic prostatitis consulted for perineal pain. On digital rectal examination the prostate was enlarged and firm, without nodules. The PSA level was 0.8 ng/mL and the catecholamines in the urine were elevated. On ultrasound a retrovesical 9 cm mass of undetermined origin measuring was present. A PET-CT scan showed a pelvic lesion measuring 9 cm with moderate increase in glucidic metabolism localized in the area of the prostate. A biopsy of the prostate revealed a neuroendocrine tumor, possibly a prostatic paraganglioma. A body scintigraphy with MIBG I-123 ruled out the presence of metastases or multifocal tumor. A radical prostatectomy with excision of the pelvic mass was performed under adrenergic blockade. One year after surgery the patient is asymptomatic and disease free.

DISCUSSION/CONCLUSIONS

Prostatic paraganglioma is a rare, usually benign tumor, which should be considered in the differential diagnosis of prostate tumors in young males. Its diagnosis is based on the determination of catecholamine in blood and 24-hour urine and in imaging studies principally scintigraphy with MIBG I-123. Diagnostic confirmation is by histopathological study. The treatment consists of radical resection under adrenergic blockade and volume expansion. Given the limited number of cases reported, it is difficult to establish prognostic factors. Malignancy is defined by clinical criteria, and requires life long follow-up.

Comparison of two peptide radiotracers for prostate carcinoma targeting

OBJECTIVES

Scintigraphy is generally not the first choice treatment for prostate cancer, although successful studies using bombesin analog radiopeptides have been performed. Recently, a novel peptide obtained using a phage display library demonstrated an affinity for prostate tumor cells. The aim of this study was to compare the use of a bombesin analog to that of a phage display library peptide (DUP-1) radiolabeled with technetium-99m for the treatment of prostate carcinoma. The peptides were first conjugated to S-acetyl-MAG3 with a 6-carbon spacer, namely aminohexanoic acid.

METHODS

The technetium-99m labeling required a sodium tartrate buffer. Radiochemical evaluation was performed using ITLC and was confirmed by high-performance liquid chromatography. The coefficient partition was determined, and in vitro studies were performed using human prostate tumor cells. Biodistribution was evaluated in healthy animals at various time points and also in mice bearing tumors.

RESULTS

The radiochemical purity of both radiotracers was greater than 95%. The DUP-1 tracer was more hydrophilic (log P = -2.41) than the bombesin tracer (log P = -0.39). The biodistribution evaluation confirmed this hydrophilicity by revealing the greater kidney uptake of DUP-1. The bombesin concentration in the pancreas was greater than that of DUP-1 due to specific gastrin-releasing peptide receptors. Bombesin internalization occurred for 78.32% of the total binding in tumor cells. The DUP-1 tracer showed very low binding to tumor cells during the in vitro evaluation, although tumor uptake for both tracers was similar. The tumors were primarily blocked by DUP1 and the bombesin radiotracer primarily targeted the pancreas.

CONCLUSION

Further studies with the radiolabeled DUP-1 peptide are recommended. With further structural changes, this molecule could become an efficient alternative tracer for prostate tumor diagnosis.

Drugs which inhibit osteoclast function suppress tumor growth through calcium reduction in bone

Prostate carcinoma frequently metastasizes to bone where the microenvironment facilitates its growth. Inhibition of bone resorption is effective in reducing tumor burden and bone destruction in prostate cancer. However, whether drugs that inhibit osteoclast function inhibit tumor growth independent of inhibition of bone resorption is unclear. Calcium is released during bone resorption and the calcium sensing receptor is an important regulator of cancer cell proliferation. The goal of this investigation was to elucidate the role of calcium released during bone resorption and to determine the impact of drugs which suppress bone resorption on tumor growth in bone. To compare tumor growth in a skeletal versus non-skeletal site, equal numbers of canine prostate cancer cells expressing luciferase (ACE-1(luc)) were inoculated into a simple collagen matrix, neonatal mouse vertebrae (vossicles), human de-proteinized bone, or a mineralized collagen matrix. Implants were placed subcutaneously into athymic mice. Luciferase activity was used to track tumor growth weekly, and at one month tumors were dissected for histologic analysis. Luciferase activity and tumor size were greater in vossicles, de-proteinized bone and mineralized collagen matrix versus non-mineralized collagen implants. The human osteoblastic prostate carcinoma cell line C4-2b also grew better in a mineral rich environment with a greater proliferation of C4-2b cells reflected by Ki-67 staining. Zoledronic acid (ZA), a bisphosphonate, and recombinant OPG-Fc, a RANKL inhibitor, were administered to mice bearing vertebral implants (vossicles) containing ACE-1 osteoblastic prostate cancer cells. Vossicles or collagen matrices were seeded with ACE-1(luc) cells subcutaneously in athymic mice (2 vossicles, 2 collagen implants/mouse). Mice received ZA (5 μg/mouse, twice/week), (OPG-Fc at 10mg/kg, 3 times/week) or vehicle, and luciferase activity was measured weekly. Histologic analysis of the tumors, vossicles and endogenous bones and serum biochemistry were performed. Antiresorptive administration was associated with decreased serum TRAP5b, reduced osteoclast numbers, and increased tibia and vossicle bone areas. ZA significantly decreased bone marrow calcium concentrations without affecting serum calcium. ZA and OPG-Fc significantly inhibited tumor growth in bone but not in collagen implants. In conclusion, the inhibitory effects of ZA or OPG-Fc on prostate tumor growth in bone are mediated via blocking bone resorption and calcium release from bone.

Celastrol suppresses angiogenesis-mediated tumor growth through inhibition of AKT/mammalian target of rapamycin pathway

Understanding the molecular basis and target of traditional medicine is critical for drug development. Celastrol, derived from Trypterygium wilfordii Hook F. ("Thunder of God Vine"), a traditional Chinese medicine plant, has been assigned anticancer activities, but its mechanism is not well understood. Here, we investigated whether Celastrol could inhibit angiogenesis-mediated tumor growth and, if so, through what mechanism. When given s.c. to mice bearing human prostate cancer (PC-3 cell) xenografts, Celastrol (2 mg/kg/d) significantly reduced the volume and the weight of solid tumors and decreased tumor angiogenesis. We found that this agent inhibited vascular endothelial growth factor (VEGF)-induced proliferation, migration, invasion, and capillary-like structure formation by primary cultured human umbilical vascular endothelial cells (HUVEC) in a dose-dependent manner. Furthermore, Celastrol abrogated VEGF-induced sprouting of the vessels from aortic rings and inhibited vascular formation in the Matrigel plug assay in vivo. To understand the molecular mechanism of these activities, we next examined the signaling pathways in treated HUVECs and PC-3 tumor cells. Celastrol suppressed the VEGF-induced activation of AKT, mammalian target of rapamycin (mTOR), and ribosomal protein S6 kinase (P70S6K). Additionally, we found that Celastrol inhibited the proliferation of prostate cancer cells and induced apoptosis, and these effects correlated with the extent of inhibition of AKT/mTOR/P70S6K signaling. Taken together, our results suggest that Celastrol targets the AKT/mTOR/P70S6K pathway, which leads to suppression of tumor growth and angiogenesis.

Proton imaging of siloxanes to map tissue oxygenation levels (PISTOL): a tool for quantitative tissue oximetry

Hexamethyldisiloxane (HMDSO) has been identified as a sensitive proton NMR indicator of tissue oxygenation (pO(2)) based on spectroscopic spin-lattice relaxometry. A rapid MRI approach has now been designed, implemented, and tested. The technique, proton imaging of siloxanes to map tissue oxygenation levels (PISTOL), utilizes frequency-selective excitation of the HMDSO resonance and chemical-shift selective suppression of residual water signal to effectively eliminate water and fat signals and pulse-burst saturation recovery (1)H echo planar imaging to map T(1) of HMDSO and hence pO(2). PISTOL was used here to obtain maps of pO(2) in rat thigh muscle and Dunning prostate R3327 MAT-Lu tumor-implanted rats. Measurements were repeated to assess baseline stability and response to breathing of hyperoxic gas. Each pO(2) map was obtained in 3(1/2) min, facilitating dynamic measurements of response to oxygen intervention. Altering the inhaled gas to oxygen produced a significant increase in mean pO(2) from 55 Torr to 238 Torr in thigh muscle and a smaller, but significant, increase in mean pO(2) from 17 Torr to 78 Torr in MAT-Lu tumors. Thus, PISTOL enabled mapping of tissue pO(2) at multiple locations and dynamic changes in pO(2) in response to intervention. This new method offers a potentially valuable new tool to image pO(2) in vivo for any healthy or diseased state by (1)H MRI.

Expression of microRNAs and protein-coding genes associated with perineural invasion in prostate cancer

BACKGROUND

Perineural invasion (PNI) is the dominant pathway for local invasion in prostate cancer. To date, only few studies have investigated the molecular differences between prostate tumors with PNI and those without it.

METHODS

To evaluate the involvement of both microRNAs and protein-coding genes in PNI, we determined their genome-wide expression with a custom microRNA microarray and Affymetrix GeneChips in 50 prostate adenocarcinomas with PNI and 7 without it. In situ hybridization (ISH) and immunohistochemistry was used to validate candidate genes.

RESULTS

Unsupervised classification of the 57 adenocarcinomas revealed two clusters of tumors with distinct global microRNA expression. One cluster contained all non-PNI tumors and a subgroup of PNI tumors. Significance analysis of microarray data yielded a list of microRNAs associated with PNI. At a false discovery rate (FDR)<10%, 19 microRNAs were higher expressed in PNI tumors than in non-PNI tumors. The most differently expressed microRNA was miR-224. ISH showed that this microRNA is expressed by perineural cancer cells. The analysis of protein-coding genes identified 34 transcripts that were differently expressed by PNI status (FDR<10%). These transcripts were down-regulated in PNI tumors. Many of those encoded metallothioneins and proteins with mitochondrial localization and involvement in cell metabolism. Consistent with the microarray data, perineural cancer cells tended to have lower metallothionein expression by immunohistochemistry than nonperineural cancer cells.

CONCLUSIONS

Although preliminary, our findings suggest that alterations in microRNA expression, mitochondrial function, and cell metabolism occur at the transition from a noninvasive prostate tumor to a tumor with PNI.