Platelet-Synthesized Testosterone in Men with Prostate Cancer Induces Androgen Receptor Signaling

Platelets have been long postulated to play a critical role in the pathogenesis of prostate cancer, although relatively little is known regarding the precise mechanisms involved. Androgen deprivation therapy (ADT) for prostate cancer eventually fails with relapse occurring in the form of castration-resistant prostate cancer (CRPC). CRPC tumors typically overexpress androgen receptor (AR), demonstrating continued dependence upon AR signaling. Platelets have been previously demonstrated to contain androgens, and we sought to explore the contribution of platelet-derived androgens in CRPC. In this study, we examined the role of platelet-derived androgens in vitro using platelets from men with CRPC, men with high-risk prostate cancer, and healthy male donors. A series of in vitro assays was performed to elucidate the impact of platelet-derived androgens on androgen-sensitive prostate tumor cells. By examining platelet-derived androgen effects on AR signaling in prostate tumor cells, we found that platelets, from men with CRPC and on ADT, strongly induce AR target genes and tumor cell proliferation. Moreover, we show a fully intact testosterone (T) biosynthetic pathway within platelets from its precursor cholesterol and demonstrate that platelets of CRPC patients with ADT resistance are able to generate T. Overall, our findings reveal an unknown capacity of platelets to synthesize T at functionally relevant levels in patients with lethal prostate cancer. Importantly, it suggests a novel paracrine mechanism of T production that may act to sustain CRPC state and potentiate therapeutic resistance.Abbreviations: ADT, androgen deprivation therapy; AR, androgen receptor; CRPC, castration-resistant prostate cancer; DHT, dihydrotestosterone; HR, high-risk disease; MS, mass spectrometry; T, testosterone     

Stereotactic body radiation therapy (SBRT) delays the emergence of castration resistance in patients with oligometastatic prostate cancer

Purpose

To investigate whether bone metastases-directed stereotactic body radiation therapy (SBRT) delays the emergence of castration resistance in patients with oligometastatic prostate cancer (OPC).

Methods and material

OPC is usually managed with androgen deprivation therapy (ADT). Migration to castration-resistant prostate cancer will inevitably occur in the majority of these patients. There are several strategies aimed to delay the emergence of castration resistance including intermittent ADT, second generation antiandrogens (abiraterone, enzalutamide) or metastases-directed SBRT. The present report describes two cases of patients with OPC that received SBRT 24 Gy/3Rx to the solitary bony lesion after ADT failure.

Results

Both cases showed complete and durable biochemical response for 13 and 17 months, respectively.

Conclusions

SBRT can be used to delay the emergence of castration resistance and the need for systemic therapy when used after ADT failure.

     

Androgen deprivation therapy and the risk of colorectal cancer in patients with prostate cancer

Purpose

Androgens are known to play an important protective role on colorectal carcinogenesis, and thus the objective of this study was to determine whether androgen deprivation therapy (ADT) is associated with an increased risk of incident colorectal cancer in patients with prostate cancer.

Methods

We conducted a population-based cohort study within the UK General Practice Research Database population which included all patients newly diagnosed with prostate cancer between 1 January 1988 and 31 December 2008, followed until 31 December 2009. Time-dependent Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) of incident primary colorectal cancer associated with the use of ADT. Secondary analyses considered cumulative duration of use and specific ADTs.

Results

The cohort included a total of 21,503 patients, of whom 184 were diagnosed with colorectal cancer during a mean (SD) follow-up 4.0 (3.0) years (rate 2.4/1,000 person-years). Overall, use of ADT was not associated with an increased risk of colorectal cancer (HR 0.99, 95 % CI 0.73–1.35). Similarly, no association was observed in terms of duration use, although this secondary analysis may have been limited by statistical power. With respect to specific ADTs, bilateral orchiectomy was the only therapy associated with an increased risk of colorectal cancer (HR 2.50, 95 % CI 1.13–5.52).

Conclusion

Overall, the use of ADT is not associated with an increased risk of incident colorectal cancer. The increased risk observed with bilateral orchiectomy may possibly be due to the prolonged androgen suppression of this therapy.     

Microvesicle microRNA profiles and functional roles between chronic hepatitis B and hepatocellular carcinoma

Objectives

Hepatocellular carcinoma (HCC) is an inflammation-related malignancy and chronic hepatitis B (CHB) predisposes to HCC. Microvesicles (MVs) transfer various bioactive molecules including microRNA (miRNA) between cells and exert biological functions. The purpose of this study was to detect CHB-MV and HCC-MV miRNAs and analyze the expression profiles and functional roles between CHB and HCC.

Methods

We examined MV miRNA profiles of CHB and HCC using miRNA microarrays. TargetScan, PicTar and miRanda were exerted to predict target genes regulating these differentially expressed miRNAs.

Results

A total of 272 and 242 aberrant fluctuation miRNAs were identified in CHB-MVs and HCC-MVs, respectively. Among them, there were 53 miRNAs co-expressing both in CHB-MVs and HCC-MVs. These miRNAs affected cellular apoptosis, proliferation and molecular signaling pathways. Among them, 25 co-expressed MV miRNAs targeted 21 inflammatory factors and these miRNAs may be a tight linkage between CHB and HCC. Interestingly, there were 14 co-expressed MV miRNAs targeting 17 oncogenes and 7 miRNAs targeting 9 tumor suppressors in the study. In addition, MVs were enriched with maladjusted miRNAs regulating zinc finger proteins and chromosome open reading frame. Those MV miRNAs may play roles in CHB developing to HCC.

Conclusions

We demonstrated that CHB and HCC displayed aberrantly co-expressed MV miRNA profiles for the first time, which may have a link between CHB and HCC. Those MV miRNAs may serve as early biomarkers for HCC and may aid to promote CHB developing to HCC.     

Stereotactic iodine-125 brachytherapy for brain tumors: temporary versus permanent implantation

Background

The natural history of non-metastatic castrate refractory prostate cancer is unknown and treatment options are limited. We present a retrospective review of 13 patients with locally advanced or high risk prostate cancer, initially treated with hormone monotherapy and then treated with prostate radiation after becoming castration refractory.

Findings

Median PSA response following prostate radiation was 67.4%. Median time to biochemical progression following radiotherapy was 15 months and to detection of metastatic disease was 18.5 months. Median survival from castration resistance (to date of death or November 2011) was 60 months, with median survival from RT 42 months.

Conclusion

Prostate radiation appears to be beneficial even in patients with potential micrometastatic disease, which supports the hypothesis that the primary tumour is important in the progression of prostate cancer. These results are an interesting addition to the literature on the biology of prostate cancer especially as this data is unlikely to be available in the future due to combined prostate radiation and androgen deprivation therapy now being the standard of care.     

Analysis of SLX4/FANCP in non-BRCA1/2-mutated breast cancer families

Background

Androgen deprivation therapy (ADT) is the mainstay therapy for men with prostate cancer. However, there are musculoskeletal side effects from ADT that increase the risk for osteoporosis and fracture, and can compromise the quality of life of these individuals. The objectives of this study are to determine the efficacy of a home-based walking exercise program in promoting bone health, physical function and quality of life in men with prostate cancer receiving ADT.

Methods/Design

A 12-month prospective, single-blinded, randomized controlled trial will be conducted to compare the Exercise Group with the Control Group. Sixty men with prostate cancer who will be starting ADT will be recruited and randomly assigned to one of the two groups: the Exercise Group will receive instructions in setting up an individualized 12-month home-based walking exercise program, while the Control Group will receive standard medical advice from the attending physician. A number of outcome measures will be used to assess bone health, physical function, and health-related quality of life. At baseline and 12 months, bone health will be assessed using dual-energy X-ray absorptiometry. At baseline and every 3 months up to 12 months, physical function will be evaluated using the Functional Assessment of Chronic Illness Therapy - Fatigue Scale, Activities-specific Balance Confidence Scale, Short Physical Performance Battery, and Six-Minute Walk Test; and health-related quality of life will be assessed using the Functional Assessment of Cancer Therapy Prostate Module and the Medical Outcomes Study 12-item Short Form Health Survey Version 2. A mixed multiple analysis of variance will be used to analyze the data.

Discussion

Musculoskeletal health management remains a challenge in men with prostate cancer receiving ADT. This study addresses this issue by designing a simple and accessible home-based walking exercise program that will potentially have significant impact on reducing the risk of fracture, promoting physical function, and ultimately improving the health-related quality of life in men with prostate cancer receiving ADT.

Trial registration

ClinicalTrials.gov: NCT00834392.     

Lokal fortgeschrittenes Prostatakarzinom und lokales Rezidiv

Background

Treatment of locally advanced prostate cancer was controversially discussed in the past. Palliative therapy only was often initiated with the implementation of androgen deprivation.

Material and methods

The most recent studies were assessed with respect to the current position of radiation therapy in comparison to surgery.

Results and discussion

According to the results of various prospective studies it could be demonstrated that a combination of radiation therapy with androgen deprivation was superior to hormone therapy. Extended radical prostatectomy was also accompanied by excellent long-term results. A multimodal therapy approach consisting of adjuvant and salvage radiation therapy led to an even greater improvement in results. For patients with locally advanced tumor stages various therapy options with a curative therapeutic approach are currently available.     

Stem cells in prostate cancer: resolving the castrate-resistant conundrum and implications for hormonal therapy

Androgen deprivation therapy (ADT) is initial systemic therapy for advanced prostate cancer and is used as an adjuvant to local therapy for high-risk disease, but responses in advanced disease are transient. Prostate cancer stem cells are a small fraction of tumor cells that give rise to malignant cells. Initial or acquired stem cell resistance to castration must therefore underlie castrate-resistant prostate cancer. We sought to review the evidence on cancer stem cells and androgen deprivation therapy to determine if prostate cancer stem cell resistance occurs from the outset, or if it is an acquired resistance. Prostate cancer stem cells do not express androgen receptor (AR) and hence should not be directly responsive to androgen deprivation therapy. However, castrate-resistant tumors that are derived from stem cells, have molecular changes such as amplification of the androgen receptor gene, or other genetic changes resulting in gain-of-function changes in AR, implying an acquired resistance to androgen deprivation. The origins of castrate-resistant tumors, with mechanisms such as androgen receptor gene amplification from androgen receptor negative prostate cancer stem cells, is an apparent conundrum. Insight into how this occurs may lead to new treatments that overcome or delay castrate-resistance. Herein, we review the evidence on cancer stem cells, the benefits of ADT, the biological basis of response to ADT, and mechanisms of castrate-resistance. We also explore the apparent conundrum of why AR-negative prostate cancer stem cells can give rise to castrate-resistant prostate cancer. We propose possible explanations that may resolve this conundrum and discuss implications for hormonal therapy.     

Androgen deprivation in LNCaP prostate tumour xenografts induces vascular changes and hypoxic stress,resulting in promotion of epithelial-to-mesenchymal transition

Background:

When single-agent androgen deprivation therapy (ADT) is administered for locally advanced prostate cancer, men usually relapse within 1–2 years with more malignant castrate-resistant disease. The reason for this is currently unknown. We now hypothesise that an initial treatment response that increases tumour hypoxia drives selection of more malignant tumours.

Methods:

The LNCaP prostate tumour xenografts were analysed for physiological (oxygen and vasculature) and genetic (PCR array) changes during longitudinal treatment with ADT (bicalutamide, 6 or 2 mg kg⁻¹ daily for 28 days).

Results:

Bicalutamide caused an immediate (within 24 h) dose-dependent fall in oxygenation in LNCaP-luc prostate tumours with a nadir of ≤0.1% oxygen within 3–7 days; this was attributed to a significant loss of tumour microvessels (window chamber study). The hypoxic nadir persisted for 10–14 days. During the next 7 days, tumours regrew, oxygenation improved and the vasculature recovered; this was inhibited by the VEGF inhibitor B20.4.1.1. Gene expression over 28 days showed marked fluctuations consistent with the physiological changes. Accompanying the angiogenic burst (day 21) was a particularly striking increase in expression of genes associated with epithelial-to-mesenchymal transition (EMT). In particular, insulin-like growth factor 1 (IGF-1) showed increases in mRNA and protein expression.

Conclusions:

Hypoxic stress caused by ADT promotes EMT, providing a mechanism for the cause of malignant progression in prostate cancer.     

The C-terminal region of Bfl-1 sensitizes non-small cell lung cancer to gemcitabine-induced apoptosis by suppressing NF-κB activity and down-regulating Bfl-1

Background

Acquisition of drug-resistance in cancer has led to treatment failure, however, their mechanisms have not been clarified yet. Recent observations indicated that aberrant expressed microRNA (miRNA) caused by chromosomal alterations play a critical role in the initiation and progression of cancer. Here, we performed an integrated genomic analysis combined with array-based comparative hybridization, miRNA, and gene expression microarray to elucidate the mechanism of drug-resistance.

Results

Through genomic approaches in MCF7-ADR; a drug-resistant breast cancer cell line, our results reflect the unique features of drug-resistance, including MDR1 overexpression via genomic amplification and miRNA-mediated TP53INP1 down-regulation. Using a gain of function study with 12 miRNAs whose expressions were down-regulated and genome regions were deleted, we show that miR-505 is a novel tumor suppressive miRNA and inhibits cell proliferation by inducing apoptosis. We also find that Akt3, correlate inversely with miR-505, modulates drug sensitivity in MCF7-ADR.

Conclusion

These findings indicate that various genes and miRNAs orchestrate to temper the drug-resistance in cancer cells, and thus acquisition of drug-resistance is intricately controlled by genomic status, gene and miRNA expression changes.     

Integrated miRNA and mRNA expression profiling of the inflammatory breast cancer subtype

Background:

MicroRNAs (miRNAs) are key regulators of gene expression. In this study, we explored whether altered miRNA expression has a prominent role in defining the inflammatory breast cancer (IBC) phenotype.

Methods:

We used quantitative PCR technology to evaluate the expression of 384 miRNAs in 20 IBC and 50 non-IBC samples. To gain understanding on the biological functions deregulated by aberrant miRNA expression, we looked for direct miRNA targets by performing pair-wise correlation coefficient analysis on expression levels of 10 962 messenger RNAs (mRNAs) and by comparing these results with predicted miRNA targets from TargetScan5.1.

Results:

We identified 13 miRNAs for which expression levels were able to correctly predict the nature of the sample analysed (IBC vs non-IBC). For these miRNAs, we detected a total of 17 295 correlated miRNA–mRNA pairs, of which 7012 and 10 283 pairs showed negative and positive correlations, respectively. For four miRNAs (miR-29a, miR-30b, miR-342-3p and miR-520a-5p), correlated genes were concordant with predicted targets. A gene set enrichment analysis on these genes demonstrated significant enrichment in biological processes related to cell proliferation and signal transduction.

Conclusions:

This study represents, to the best of our knowledge, the first integrated analysis of miRNA and mRNA expression in IBC. We identified a set of 13 miRNAs of which expression differed between IBC and non-IBC, making these miRNAs candidate markers for the IBC subtype.     

Androgen Receptor Splice Variants in the Era of Enzalutamide and Abiraterone

The FDA approvals of enzalutamide and abiraterone have rapidly changed the clinical landscape of prostate cancer treatment. Both drugs were designed to further suppress androgen receptor (AR) signaling, which is restored following first-line androgen deprivation therapies. Resistance to enzalutamide and abiraterone, however, is again marked by a return of AR signaling, indicating a remarkable “addiction” of prostate cancer cells to the AR pathway. Several mechanisms of castration resistance have been uncovered in the past decades, featuring a wide spectrum of molecular alterations that may explain sustained AR signaling in castration-resistant prostate cancers (CRPC). Among these, the androgen receptor splice variants (AR-Vs), particularly variant 7 (AR-V7), have been implicated in resistance to enzalutamide and abiraterone in preclinical studies, and they cannot be targeted by currently available AR-directed drugs. Drug development for AR-V-associated CRPC may therefore be necessary to augment the preexisting treatment repertoire. In this mini-review, we will discuss general mechanisms of resistance to AR-directed therapies, with a focus on the role of androgen receptor splice variants in the new era of treating advanced prostate cancer with enzalutamide and abiraterone.     

Integrin αvβ3 and CD44 pathways in metastatic prostate cancer cells support osteoclastogenesis via a Runx2/Smad 5/receptor activator of NF-κB ligand signaling axis

Background

Bone loss and pathological fractures are common skeletal complications associated with androgen deprivation therapy and bone metastases in prostate cancer patients. We have previously demonstrated that prostate cancer cells secrete receptor activator of NF-kB ligand (RANKL), a protein essential for osteoclast differentiation and activation. However, the mechanism(s) by which RANKL is produced remains to be determined. The objective of this study is to gain insight into the molecular mechanisms controlling RANKL expression in metastatic prostate cancer cells.

Results

We show here that phosphorylation of Smad 5 by integrin ??v??3 and RUNX2 by CD44 signaling, respectively, regulates RANKL expression in human-derived PC3 prostate cancer cells isolated from bone metastasis. We found that RUNX2 intranuclear targeting is mediated by phosphorylation of Smad 5. Indeed, Smad5 knock-down via RNA interference and inhibition of Smad 5 phosphorylation by an ??v inhibitor reduced RUNX2 nuclear localization and RANKL expression. Similarly, knockdown of CD44 or RUNX2 attenuated the expression of RANKL. As a result, conditioned media from these cells failed to support osteoclast differentiation in vitro. Immunohistochemistry analysis of tissue microarray sections containing primary prostatic tumor (grade2-4) detected predominant localization of RUNX2 and phosphorylated Smad 5 in the nuclei. Immunoblotting analyses of nuclear lysates from prostate tumor tissue corroborate these observations.

Conclusions

Collectively, we show that CD44 signaling regulates phosphorylation of RUNX2. Localization of RUNX2 in the nucleus requires phosphorylation of Smad-5 by integrin ??v??3 signaling. Our results suggest possible integration of two different pathways in the expression of RANKL. These observations imply a novel mechanistic insight into the role of these proteins in bone loss associated with bone metastases in patients with prostate cancer.     

Genetic polymorphisms of CYP17A1 in steroidogenesis pathway are associated with risk of progression to castration-resistant prostate cancer in Japanese men receiving androgen deprivation therapy

Background

Hormone ablation therapy is the standard therapy for prostate cancer; however, there are large individual differences in the duration of response to the therapy. We investigated, in this retrospective multicenter study, the association between genetic polymorphic variations in steroidogenesis-related genes and the risk of progression to castration-resistant prostate cancer (CRPC) in Japanese patients after androgen deprivation therapy.

Methods

Two hundred and fourteen Japanese patients with prostate cancer who were receiving androgen deprivation therapy were enrolled in this study. We investigated 22 single-nucleotide polymorphisms (SNPs) from 8 genes related to steroidogenesis. The SNPs were assayed by polymerase chain reaction (PCR)-based methods. The different genotypes in this cohort were analyzed according to a case–control status of progression to CRPC at the median duration of hormonal therapy. A logistic regression method with adjustments for patients’ characteristics was applied for the analysis.After applying the logistic regression method, we performed Cox regression analysis, following Kaplan–Meier and log-rank analyses.

Results

In the logistic regression analysis four genetic polymorphisms, rs743572, rs6162, rs6163, and rs1004467, in the CYP17A1 gene were significantly associated with a risk of progression to CRPC (p < 0.05). Cox regression analysis for these SNPs showed an association of risk of progression to CRPC with the rs743572 genotype (p = 0.02, odds ratio [OR] 0.43, 95 % confidence interval [CI] 0.22–0.85).

Conclusion

The genetic backgrounds for CYP17A1 genes could influence the progression of prostate cancer to CRPC after androgen deprivation therapy.     

TGF-β1 alters microRNA profile in human gastric cancer cells

Objective: MicroRNAs (miRNAs) are important regulators that play a key role in tumorigenesis and tumor progression. Transforming growth factor-β1 (TGF-β1) is involved in invasion and metastasis in many tumors. In this study, we investigated the microRNAs (miRNA) profiles altered by TGF-β1 in gastric cancer (GC) cells. Methods: We detected the expression profiles of miRNA by miRNA microarray and quantitative real-time polymerase chain reaction. Migration and invasion, wound-healing assay, prediction of miRNA targets, Western blot and qRT-PCR analysis were carried out to determine the role of one selected miRNA, namely miR-193b, in affecting the biological behaviors of GC BGC823 cells. Results: Among 847 human miRNAs in the microarray, three miRNAs (miR-27a, miR-29b-1 and miR-194) were up-regulated and three (miR-574-3p, miR-193b and miR-130b) were down-regulated in BGC823 cells treated with TGF-β1 compared with control. miR-193b suppressed the invasion and metastasis of GC cells in vivo and in vitro, and down-regulated urokinase-type plasminogen activator (uPA) protein in GC cells. Conclusions: TGF-β1 altered miRNA expression profile in BGC823 cells. Among the altered miRNAs, TGF-β1 induced the down-regulation of miR-193b, which inhibited cell invasion and metastasis in vivo and in vitro, and down-regulated uPA protein in GC cells.     

A phase II trial of androgen deprivation therapy (ADT) plus chemotherapy as initial treatment for local failures or advanced prostate cancer

Purpose

Long-term hormonal ablation in prostate cancer is associated with decreased overall health and quality of life. Few reports emphasized the role of chemotherapy in the management of early stage prostate cancer. This study analyzed the safety and efficacy of androgen deprivation therapy (ADT) plus chemotherapy as initial treatment for patients identified as local failures or not eligible for prostatectomy or radiation therapy due to advanced disease presentation.

Methods

Enrolled patients received ADT in the form of leuprolide every 12 weeks for 24 months with bicalutamide initiating after the completion of chemotherapy. Chemotherapy consisted of ketoconazole and doxorubicin for weeks 1, 3, and 5 and estramustine and docetaxel and for weeks 2, 4 and 6. During weeks 7 and 8, no treatment was received.

Results

Forty-six patients were enrolled, and forty-five patients were evaluable. Median progression-free survival (PFS) was 23.4 months. Median overall survival (OS) was 53.7 months. Out of 45 patients with measurable disease, 22 patients had an objective response: 9 patients achieved a complete response; 2 patients achieved a partial response; 10 patients achieved stable disease. Frequent grade 3 adverse events included elevated ALT (17 %), hypokalemia (13 %), and hypophosphatemia (13 %). Grade 4 adverse events were rare and included low bicarbonate (2 %), hypokalemia (2 %), leukocytopenia (2 %), and neutropenia (2 %).

Conclusions

The treatment demonstrated clinical benefit in all patient subsets with minimal reversible treatment-related adverse events. Subgroup analysis suggests that having prior local therapy resulted in greater PFS and OS.