Statins reduce the androgen sensitivity and cell proliferation by decreasing the androgen receptor protein in prostate cancer cells

Association between Statin Use and Clinical Outcomes in Patients with De Novo Metastatic Prostate Cancer: A Propensity Score-weighted Analysis

PURPOSE

Numerous studies have produced conflicting findings regarding the efficacy of statins in prostate cancer treatment. Our objective was to examine the correlation between statin usage and clinical outcomes in Taiwanese men with de novo metastatic prostate cancer.

MATERIALS AND METHODS

We identified patients diagnosed with de novo metastatic prostate cancer from the Chang Gung Research Database spanning the years 2007 to 2020. To minimize confounding bias, we employed the inverse probability of treatment weighting (IPTW) method. Clinical outcomes were assessed using IPTW-adjusted Kaplan-Meier curves. Multivariate Cox proportional hazard regression analysis was utilized to evaluate the association between mortality and clinical factors.

RESULTS

The study cohort comprised 1,716 statin users and 276 non-users. Patients who used statins exhibited a longer median overall survival (85.4 months compared to 58.2 months; p=0.001) and cancer-specific survival (112.6 months compared to 75.7 months; p<0.001) compared to non-users. The median time to the development of castration-resistant status was similar between statin users and non-users (p=0.069). Multivariable Cox proportional hazards regression analysis, after IPTW adjustment, demonstrated that statin use was associated with improved overall survival.

CONCLUSIONS

Our study indicates that the use of statins following a de novo metastatic prostate cancer diagnosis enhances survival outcomes. However, statins did not appear to delay the onset of castration-resistant status. Further large-scale and long-term studies are warranted to investigate the biological effects of statins in men with prostate cancer.

Overcoming statin resistance in prostate cancer cells by targeting the 3-hydroxy-3-methylglutaryl-CoA-reductase

Prostate cancer is the most prevalent malignancy in men. While diagnostic and therapeutic interventions have substantially improved in recent years, disease relapse, treatment resistance, and metastasis remain significant contributors to prostate cancer-related mortality. Therefore, novel therapeutic approaches are needed. Statins are inhibitors of the 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway which plays an essential role in cholesterol homeostasis. Numerous preclinical studies have provided evidence for the pleiotropic antitumor effects of statins. However, results from clinical studies remain controversial and have shown substantial benefits to even no effects on human malignancies including prostate cancer. Potential statin resistance mechanisms of tumor cells may account for such discrepancies. In our study, we treated human prostate cancer cell lines (PC3, C4-2B, DU-145, LNCaP) with simvastatin, atorvastatin, and rosuvastatin. PC3 cells demonstrated high statin sensitivity, resulting in a significant loss of vitality and clonogenic potential (up to - 70%; p < 0.001) along with an activation of caspases (up to 4-fold; p < 0.001). In contrast, C4-2B and DU-145 cells were statin-resistant. Statin treatment induced a restorative feedback in statin-resistant C4-2B and DU-145 cells through upregulation of the HMGCR gene and protein expression (up to 3-folds; p < 0.01) and its transcription factor sterol-regulatory element binding protein 2 (SREBP-2). This feedback was absent in PC3 cells. Blocking the feedback using HMGCR-specific small-interfering (si)RNA, the SREBP-2 activation inhibitor dipyridamole or the HMGCR degrader SR12813 abolished statin resistance in C4-2B and DU-145 and induced significant activation of caspases by statin treatment (up to 10-fold; p < 0.001). Consistently, long-term treatment with sublethal concentrations of simvastatin established a stable statin resistance of a PC3SIM subclone accompanied by a significant upregulation of both baseline as well as post-statin HMGCR protein (gene expression up to 70-fold; p < 0.001). Importantly, the statin-resistant phenotype of PC3SIM cells was reversible by HMGCR-specific siRNA and dipyridamole. Our investigations reveal a key role of a restorative feedback driven by the HMGCR/SREBP-2 axis in statin resistance mechanisms of prostate cancer cells.

Improved Prostate-Specific Membrane Antigen (PSMA) Stimulation Using a Super Additive Effect of Dutasteride and Lovastatin In Vitro

Prostate-specific membrane antigen (PSMA)-based imaging improved the detection of primary, recurrent and metastatic prostate cancer. However, in certain patients, a low PSMA surface expression can be a limitation for this promising diagnostic tool. Pharmacological induction of PSMA might be useful to further improve the detection rate of PSMA-based imaging. To achieve this, we tested dutasteride (Duta)-generally used for treatment of benign prostatic enlargement-and lovastatin (Lova)-a compound used to reduce blood lipid concentrations. We aimed to compare the individual effects of Duta and Lova on cell proliferation as well as PSMA expression. In addition, we tested if a combination treatment using lower concentrations of Duta and Lova can further induce PSMA expression. Our results show that a treatment with ≤1 μM Duta and ≥1 μM Lova lead to a significant upregulation of whole and cell surface PSMA expression in LNCaP, C4-2 and VCaP cells. Lower concentrations of Duta and Lova in combination (0.5 μM Duta + 0.5 μM Lova or 0.5 μM Duta + 1 μM Lova) were further capable of enhancing PSMA protein expression compared to a single compound treatment using higher concentrations in all tested cell lines (LNCaP, C4-2 and VCaP).

Development of a High-Throughput Screening Assay for Small-Molecule Inhibitors of Androgen Receptor Splice Variants

The role of the androgen receptor (AR) in the progression of prostate cancer (PCa) is well established and competitive inhibition of AR ligand binding domain (LBD) has been the mainstay of antiandrogen therapies for advanced and metastatic disease. However, the efficacy of such drugs is often limited by the emergence of resistance, mediated through point mutations and receptor splice variants lacking the AR-LBD. As a result, the prognosis for patients with malignant, castrate-resistant disease remains poor. The amino terminal domain (NTD) of the AR has been shown to be critical for AR function. Its modular activation function (AF-1) is important for both gene regulation and participation in protein–protein interactions. However, due to the intrinsically disordered structure of the domain, its potential as a candidate for therapeutic intervention has been generally overlooked. In this article, we describe the design and development of a functional cell-based assay aimed at identifying small-molecule inhibitors of the AR-NTD. We demonstrate the suitability of the assay for high-throughput screening platforms and validate two initial hits emerging from a small, targeted, library screen in PCa cells.

Combination therapy with novel androgen receptor antagonists and statin for castration-resistant prostate cancer

BACKGROUND

One of the growth mechanisms of castration-resistant prostate cancer (CRPC) is de novo androgen synthesis from intracellular cholesterol, and statins may be able to inhibit this mechanism. In addition, statins have been reported to suppress the expression of androgen receptors (ARs) in prostate cancer cell lines. In this study, we investigated a combination therapy of novel AR antagonists and statin, simvastatin, for CRPC.

METHODS

LNCaP, 22Rv1, and PC-3 human prostate cancer cell lines were used. We developed androgen-independent LNCaP cells (LNCaP-LA). Microarray analysis was performed, followed by pathway analysis, and mRNA and protein expression was evaluated by quantitative real-time polymerase chain reaction and Western blot analysis, respectively. Cell viability was determined by MTS assay and cell counts. All evaluations were performed on cells treated with simvastatin and with or without AR antagonists (enzalutamide, apalutamide, and darolutamide).

RESULTS

The combination of darolutamide and simvastatin most significantly suppressed proliferation in LNCaP-LA and 22Rv1 cells. In a 22Rv1-derived mouse xenograft model, the combination of darolutamide and simvastatin enhanced the inhibition of cell proliferation. In LNCaP-LA cells, the combination of darolutamide and simvastatin led to reduction in the mRNA expression of the androgen-stimulated genes, KLK2 and PSA; however, this reduction in expression did not occur in 22Rv1 cells. The microarray data and pathway analyses showed that the number of differentially expressed genes in the darolutamide and simvastatin-treated 22Rv1 cells was the highest in the pathway termed "role of cell cycle." Consequently, we focused our efforts on the cell cycle regulator polo-like kinase 1 (PLK1), cyclin-dependent kinase 2 (CDK2), and cell cycle division 25C (CDC25C). In 22Rv1 cells, the combination of darolutamide and simvastatin suppressed the mRNA and protein expression of these three genes. In addition, in PC-3 cells (which lack AR expression), the combination of simvastatin and darolutamide enhanced the suppression of cell proliferation and expression of these genes.

CONCLUSIONS

Simvastatin alters the expression of many genes involved in the cell cycle in CRPC cells. Thus, the combination of novel AR antagonists (darolutamide) and simvastatin can potentially affect CRPC growth through both androgen-dependent and androgen-independent mechanisms.

Association of statins use and mortality outcomes in prostate cancer patients who received androgen deprivation therapy: a systematic review and meta-analysis

Introduction

While several recent studies investigated the influence of statins on survival outcomes in prostate cancer (PCa) patients on androgen deprivation therapy (ADT), definitive conclusions are still missing. The present systematic review and meta-analysis aimed to develop an overarching framework for the association of statins use and survival outcomes in PCa patients who receive ADT.

Material and methods

We conducted a systematic review and meta-analysis of the literature assessing the survival outcomes for statin compared to non-statin users in PCa patients who received ADT. We searched PubMed and Web of Science for studies published before March 1, 2021. We used the random effect model in the presence of heterogeneity and the fixed-effects model in the absence of heterogeneity per the I² statistic. We did two meta-analyses; the primary meta-analysis was accomplished for articles reporting cancer-specific survival (CSS) as an outcome. A secondary meta-analysis was completed for articles reporting overall survival (OS) as an outcome.

Results

Ten studies were eligible for inclusion. Nine studies included in the first meta-analysis comprising 136,285 patients showed no statistically significant difference in CSS (HR 0.77; 95% CI 0.49–1.21) between statin users and non-users in PCa patients who received ADT. In four studies included in the second meta-analysis comprising 95,032 patients, statin users had a significantly better OS compared to non-users (HR 0.67; 95% CI 0.62–0.73).

Conclusions

Although the combination of statins and ADT in PCa patients significantly improves OS, it seems not to be through an effect on cancer-specific factors.

The Effects of Statins on Prostate Cancer Patients Receiving Androgen Deprivation Therapy or Definitive Therapy: A Systematic Review and Meta-Analysis

Mortality associated with statin use has been reported in prostate cancer (PCa) patients treated with androgen deprivation therapy (ADT) or definitive therapy in several observational studies, although the results have varied. This study aimed to analyze the association of statin use with all-cause mortality and cancer-specific mortality among PCa patients receiving ADT or definitive therapy as their primary treatment and to examine the effect of statin initiation (pre-ADT) timing on outcomes. A systematic literature search of PubMed, the Cochrane library, and Embase was conducted from database inception to 4 October 2021. In total, 12 eligible studies from 976 references were included in the final analysis. The results showed that statin use was associated with a significant reduction in the risks of all-cause mortality (hazard ratio (HR) = 0.73, 95% confidence interval (CI) = 0.64–0.84, p < 0.0001) and cancer-specific mortality (HR = 0.61, 95% CI = 0.49–0.77, p < 0.0001) in PCa patients receiving ADT. However, statin use before ADT initiation did not significantly lower the risk of all-cause mortality (HR = 0.87, 95% CI = 0.66–1.16, p = 0.35) or cancer-specific mortality (HR = 0.84, 95% CI = 0.62–1.13, p = 0.25) in advanced PCa patients receiving ADT. In contrast, statin use was not associated with a significantly reduced risk of all-cause mortality (HR = 0.69, 95% CI = 0.39–1.21, p = 0.20), but it was associated with a reduced risk of cancer-specific mortality (HR = 0.82, 95% CI = 0.68–0.98, p = 0.03) in PCa patients receiving definitive therapy. This review indicated that statin use in combination with ADT was correlated with better all-cause and cancer-specific mortality in PCa patients. However, the beneficial effect might not come from statin use before ADT initiation. In addition, statin use in combination with definitive therapy was correlated with a reduced risk of cancer-specific mortality in PCa patients. In the future, randomized controlled trials are needed to validate the efficacy of statin use in combination with primary treatment for PCa among PCa patients.

Testosterone Deficiency Promotes Hypercholesteremia and Attenuates Cholesterol Liver Uptake via AR/PCSK9/LDLR Pathways

BACKGROUND

Testosterone deficiency is reportedly correlated with an elevation of cholesterol in plasma, but the mechanism remains unclear. Our objective was to investigate the effects of testosterone deficiency on cholesterol metabolism and the corresponding molecular changes in vivo and in vitro.

METHODS

SD rats were randomized into three groups: sham-operated (SHAM), subtotal orchiectomized (SO), and orchiectomized (ORX) and fed for 8 weeks. HepG2 cells were cultured with medium containing testosterone with the final concentrations of 0, 10, 30, and 300 nM. Method of isotope tracing and fluorescence labelling was adopted to investigate cholesterol metabolism. Several key molecules of cholesterol metabolism were also analyzed.

RESULTS

SO and ORX rats displayed dysfunctional liver uptake of cholesterol. HepG2 cells incubated with testosterone of lower and excessive level exhibited reduced capacity of cholesterol uptake. Further investigation revealed that lack of testosterone induced increased proprotein convertase subtilisin/kexin type 9 (PCSK9) and decreased low-density lipoprotein receptor (LDLR) both in vivo and in vitro. Moreover, the androgen receptor (AR) antagonist flutamide mimicked the effects of testosterone deficiency on PCSK9 and LDLR indicating the role of AR as a mediator in triggering attenuating liver cholesterol uptake in which testosterone instead of dihydrotestosterone (DHT) is the major functional form of androgen.

CONCLUSION

Testosterone deficiency attenuated cholesterol liver uptake mediated by the PCSK9-LDLR pathway, in which AR and testosterone without transforming to DHT play important roles.

Outcomes of Screening for Prostate Cancer Among Men Who Use Statins

Importance

Prostate-specific antigen (PSA) screening for prostate cancer has resulted in a slight reduction in prostate cancer mortality but also a concomitant overdiagnosis of low-risk tumors. Prostate-specific antigen levels are affected by use of cholesterol-lowering statin drugs, but the association of statin use with PSA screening performance is unknown.

Objective

To investigate whether statin use was associated with outcomes of a randomized PSA-based prostate cancer screening intervention.

Design, Setting, and Participants

This post hoc subgroup analysis of a cohort from a population-based randomized clinical trial used data from the population-based Finnish Randomized Study of Prostate Cancer Screening, which randomized men to PSA screening or routine care from March 1, 1996, to December 31, 1999, with follow-up continuing until December 31, 2015. The population included all men aged 55 to 67 years at baseline and residing in the Tampere or Helsinki districts of Finland. Information on statin purchases from 1996 to 2009 was obtained from a national prescription registry. Eligible men were identified from the population registry of Finland. Prevalent prostate cancer cases at baseline were excluded. Data were analyzed from January 1, 2019 to March 31, 2021.

Interventions

Three invitations for PSA screening at 4-year intervals from 1996 to 2007 vs routine care.

Main Outcomes and Measures

Risk for prostate cancer overall, high-risk disease, and prostate cancer mortality in the screening group vs the control group as an intention-to-treat analysis. The analysis was stratified by statin use.

Results

The study comprised 78 606 men (median age, 59 years [range, 55-67 years]) with statin purchase data available. Although PSA screening was associated with increased prostate cancer incidence among statin nonusers (screening vs control, 11.2 vs 8.6 per 1000 person-years); rate ratio [RR], 1.31; 95% CI, 1.24-1.38), no similar increase in incidence was observed among statin users (6.9 vs 5.9 per 1000 person-years; RR, 1.02; 95% CI, 0.95-1.10; P < .001 for interaction). Incidence of low-risk (Gleason score 6) and localized tumors was lower among statin users, whereas detection of tumors with a Gleason score of 8 to 10 was similar. Screening was associated with a lower incidence of metastatic tumors regardless of statin use.

Conclusion and Relevance

In this post hoc subgroup analysis of a cohort from a population-based randomized clinical trial, PSA screening among statin users was associated with a decreased incidence of advanced prostate cancer that was similar among statin nonusers, but with less increase in detection of low-grade localized tumors in statin users than in nonusers. These findings suggest that statin use does not materially compromise benefits of PSA-based screening.

Post-Translational Modifications That Drive Prostate Cancer Progression

While a protein primary structure is determined by genetic code, its specific functional form is mostly achieved in a dynamic interplay that includes actions of many enzymes involved in post-translational modifications. This versatile repertoire is widely used by cells to direct their response to external stimuli, regulate transcription and protein localization and to keep proteostasis. Herein, post-translational modifications with evident potency to drive prostate cancer are explored. A comprehensive list of proteome-wide and single protein post-translational modifications and their involvement in phenotypic outcomes is presented. Specifically, the data on phosphorylation, glycosylation, ubiquitination, SUMOylation, acetylation, and lipidation in prostate cancer and the enzymes involved are collected. This type of knowledge is especially valuable in cases when cancer cells do not differ in the expression or mutational status of a protein, but its differential activity is regulated on the level of post-translational modifications. Since their driving roles in prostate cancer, post-translational modifications are widely studied in attempts to advance prostate cancer treatment. Current strategies that exploit the potential of post-translational modifications in prostate cancer therapy are presented.

Acute Statin Treatment Improves Antibody Accumulation in EGFR- and PSMA-Expressing Tumors

PURPOSE

Statins are cholesterol-depleting drugs used to treat patients with hypercholesterolemia. Preclinically, statins disrupt trafficking of receptors present at the cell membrane. Membrane receptors, defined as tumor biomarkers and therapeutic targets, are often internalized by an endocytic pathway. Indeed, receptor endocytosis and recycling are dynamic mechanisms that often affect receptor density at the cell surface. In therapies using monoclonal antibodies (mAb), a downregulation in receptor density at the cell surface decreases antibody binding to the extracellular domain of the membrane receptor. Here, we determined the potential of lovastatin, simvastatin, and rosuvastatin in preclinically modulating epidermal growth factor receptor (EGFR) and prostate-specific membrane antigen (PSMA) receptor density at the tumor cell surface.

EXPERIMENTAL DESIGN

Small-animal PET was used to study the binding of ⁸⁹Zr-labeled antibodies in ectopic xenografts. Ex vivo analyses were performed to determine changes in endocytic proteins, EGFR, and PSMA surface levels.

RESULTS

Acute statin treatment using lovastatin, simvastatin, or rosuvastatin enhanced tumors' avidity for the mAbs panitumumab, cetuximab, and huJ591. Statins temporarily modulated caveolin-1, cavin-1, endophilin, clathrin, and dynamin proteins in EGFR- and PSMA-overexpressing xenografts.

CONCLUSIONS

These data show the potential of statins as pharmacologic modulators of endocytic proteins for improved tumors' accumulation of mAbs. The translational significance of these findings lies in the potential of statins to temporarily modulate the heterogeneous presence of receptors at the cell membrane, a characteristic often associated with poor response in tumors to therapeutic antibodies.

High-throughput screen identifies 5-HT receptor as a modulator of AR and a therapeutic target for prostate cancer

BACKGROUND

Eradication of persistent androgen receptor (AR) activity in castration-resistant prostate cancer may be a promising strategy to overcome castration resistance. We aimed to identify novel compounds that inhibit AR activity and could be potential therapeutic agents for prostate cancer.

METHODS

A high-throughput screening system involving cell lines stably expressing AR protein and AR-responsive luciferase was employed for the 1260 compound library. Molecular and antitumor effects on candidate pathways that interacted with AR signaling were examined in prostate cancer cells expressing AR.

RESULTS

The high-throughput screening identified various potential compounds that interfered with AR signaling through known and novel pathways. Among them, a 5-hydroxytryptamine 5A (5-HT5A) receptor antagonist suppressed AR activity through protein kinase A signaling, which was confirmed by 5-HT5A receptor knockdown. Consistently, 5-HT5A receptor inhibitors showed cytotoxic effects toward prostate cancer cells.

CONCLUSIONS

Taken together, this study identifies 5-HT5A receptor as a promising therapeutic target for prostate cancer via its interaction with AR signaling.

Effects of isolated or combined exposure to sibutramine and rosuvastatin on reproductive parameters of adult male rats

Many obese patients are exposed to hypolipidemic and serotonin-norepinephrine reuptake inhibitor (SNRI) drugs. Statins are one of the most marketed drugs in the world to treat dyslipidemia, while sibutramine, a SNRI drug, is prescribed in some countries to treat obesity and is detected as an additive in many adulterated weight loss supplements marketed worldwide. Previous studies reported adverse effects of isolated exposure to these drugs on male rat reproductive parameters. In the present work, we further investigated male reproductive toxicity of these drugs, administered in isolation or combination in adult rats for a longer period of treatment. Adult male rats (90 days) were treated (gavage) for 70 days with saline and dimethyl sulfoxide (control), sibutramine (10 mg/kg), rosuvastatin (5 mg/kg), or rosuvastatin combined with sibutramine. Sibutramine alone or with rosuvastatin, promoted a reduction in food intake and body weight gain, weight of the epididymis, ventral prostate and seminal vesicle; as well as decreased sperm reserves and transit time through the epididymis; androgen depletion; and increased index of cytoplasmic droplet. The rosuvastatin-treated group showed reduced frequency of ejaculation. Exposure to this drug alone or combined with sibutramine impaired epididymal morphology. Co-exposed rats had altered epididymal morphometry, and seminal vesicle and testis weights. The rats also showed decreased fertility after natural mating and a trend toward a delay in ejaculation, suggesting a small synergistic effect of these drugs. Given the greater reproductive efficiency of rodents, the results obtained in the present study raise concern regarding possible fertility impairment in men taking statins and SNRI drugs.

The effect of statins on advanced prostate cancer patients with androgen deprivation therapy or abiraterone/enzalutamide: A systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

To evaluate the effects of statin use on the treatment outcomes (i.e. overall survival and cancer-specific survival) among advanced prostate cancer (PCa) patients treated with androgen deprivation therapy (ADT) or abiraterone/enzalutamide.

METHODS

The original studies, examining the effects of statins on the outcomes (i.e. overall survival and cancer-specific survival) among PCa patients treated with ADT or abiraterone/enzalutamide, were identified through a systematic search by two independent reviewers in the PubMed, Cochrane, Embase, American Society of Clinical Oncology and European Society of Medical Oncology databases. Databases were searched using keywords (abiraterone OR enzalutamide OR androgen deprivation therapy) AND statin. In total, nine eligible studies from 111 references were included for final analysis.

RESULTS AND DISCUSSION

Statin use significantly lowered the risk of all-cause mortality (100 709 patients, HR = 0.73, 95%CI = 0.64-0.83, P < .00001) and the risk of cancer-specific mortality (100 343 patients, HR = 0.64, 95% CI = 0.53-0.77, P < .00001) in advanced PCa patients treated with ADT. The sensitivity analysis showed that the results were reliable. However, it could not generate reliable evidence in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone/enzalutamide, as relevant studies were limited and had inconsistent results.

WHAT IS NEW AND CONCLUSION

The review indicated that the use of statins in combination with ADT was associated with better all-cause survival and cancer-specific survival in patients with advanced PCa. Randomized controlled trials should be conducted to establish efficacy of statins among PCa patients.

The impact of statins in combination with androgen deprivation therapyin patients with advanced prostate cancer: A large observational study

BACKGROUND

Statins are thought to possess antineoplastic properties related to their effect on cell proliferation and steroidogenesis. Progression to castrate resistant prostate cancer (CaP) includes de-regulation of androgen synthesis suggesting a role for statins in this setting. Our goal was to assess the role of statin use on oncologic outcomes in patients with advanced CaP being treated with androgen deprivation therapy (ADT).

METHODS

The national VA database was used to identify all men diagnosed with CaP who were treated with ADT for at least 6 months between 2000 and 2008 with follow-up through May 2016. Our cohort was stratified based on statin use of at least 6 months duration during the same time. Multivariable Cox proportional hazards analyses with inverse propensity score weighted (IPSW) adjustment were calculated to assess for primary outcomes of CaP-specific survival (CSS), overall survival (OS) and skeletal related events (SREs).

RESULTS

A total of 87,346 patients on ADT were included in the study cohort, 53,360 patients used statins and 33,986 did not. Statin users were younger in age (median 73 vs. 76, P < 0.001), more likely to have a higher Charlson comorbidity index (CCI) >3 (3.1% vs. 2.5%, P < 0.001) and more likely to have a high grade (Gleason score 8-10) cancer (12.3% vs. 10.9%, P < 0.001). Statin users had longer OS (median 6.5 vs. 4.0 years P < 0.001) and decreased death from CaP (5-year CSS 94.0% vs. 87.3%, P < 0.001). Statin use was also associated with longer time to a SRE (median 5.9 vs. 3.7 years, P < 0.001). On multivariable Cox proportional hazards analysis with inverse propensity score weighted, statin use was an independent predictor of improved OS (hazard ratio [HR] 0.66, confidence interval [CI] 0.63-0.68; P < 0.001), CSS (HR 0.56, 95% CI 0.53-0.60; P < 0.001), and SREs (HR 0.64, 95%CI 0.59-0.71; P < 0.001) when controlling for age, race, Charlson comorbidity index, prostate-specific antigen, and Gleason score.

CONCLUSION

The use of statins in men on ADT for CaP is associated with improved CSS and OS. Statins are inexpensive, well-tolerated medications that offer a promising adjunct to ADT, but require further prospective studies.

Pirfenidone, an Anti-Fibrotic Drug, Suppresses the Growth of Human Prostate Cancer Cells by Inducing G₁ Cell Cycle Arrest

Pirfenidone (PFD) is an anti-fibrotic drug used to treat idiopathic pulmonary fibrosis by inducing G₁ cell cycle arrest in fibroblasts. We hypothesize that PFD can induce G₁ cell cycle arrest in different types of cells, including cancer cells. To investigate the effects of PFD treatment on the growth of human prostate cancer (PCa) cells, we used an androgen-sensitive human PCa cell line (LNCaP) and its sublines (androgen-low-sensitive E9 and F10 cells and androgen-insensitive AIDL cells), as well as an androgen-insensitive human PCa cell line (PC-3). PFD treatment suppressed the growth of all PCa cells. Transforming growth factor β1 secretion was significantly increased in PFD-treated PCa cells. In both LNCaP and PC-3 cells, PFD treatment increased the population of cells in the G₀/G₁ phase, which was accompanied by a decrease in the S/G₂ cell population. CDK2 protein expression was clearly decreased in PFD-treated LNCaP and PC-3 cells, whereas p21 protein expression was increased in only PFD-treated LNCaP cells. In conclusion, PFD may serve as a novel therapeutic drug that induces G₁ cell cycle arrest in human PCa cells independently of androgen sensitivity. Thus, in the tumor microenvironment, PFD might target not only fibroblasts, but also heterogeneous PCa cells of varying androgen-sensitivity levels.

Inhibition of de novo lipogenesis targets androgen receptor signaling in castration-resistant prostate cancer

Standard of care for metastatic castration-resistant prostate cancer (mCRPC) mainly relies on suppression of androgen receptor (AR) signaling. This approach has no lasting benefit due to the emergence of resistance mechanisms, such as ligand-independent splicing variant AR-V7. A metabolic feature of mCRPC is the upregulation of de novo lipogenesis to provide substrates and fuel for metastatic spread. Whether increased levels of fats affect AR signaling to promote an aggressive disease remains to be determined. Using a selective and potent inhibitor of fatty acid synthase we demonstrate that suppression of this key enzyme inhibits AR, most importantly AR-V7, and reduces mCRPC growth. Our findings offer a therapeutic opportunity for mCRPC and a potential mechanism to overcome resistance to AR inhibitors.

A hallmark of prostate cancer progression is dysregulation of lipid metabolism via overexpression of fatty acid synthase (FASN), a key enzyme in de novo fatty acid synthesis. Metastatic castration-resistant prostate cancer (mCRPC) develops resistance to inhibitors of androgen receptor (AR) signaling through a variety of mechanisms, including the emergence of the constitutively active AR variant V7 (AR-V7). Here, we developed an FASN inhibitor (IPI-9119) and demonstrated that selective FASN inhibition antagonizes CRPC growth through metabolic reprogramming and results in reduced protein expression and transcriptional activity of both full-length AR (AR-FL) and AR-V7. Activation of the reticulum endoplasmic stress response resulting in reduced protein synthesis was involved in IPI-9119–mediated inhibition of the AR pathway. In vivo, IPI-9119 reduced growth of AR-V7–driven CRPC xenografts and human mCRPC-derived organoids and enhanced the efficacy of enzalutamide in CRPC cells. In human mCRPC, both FASN and AR-FL were detected in 87% of metastases. AR-V7 was found in 39% of bone metastases and consistently coexpressed with FASN. In patients treated with enzalutamide and/or abiraterone FASN/AR-V7 double-positive metastases were found in 77% of cases. These findings provide a compelling rationale for the use of FASN inhibitors in mCRPCs, including those overexpressing AR-V7.

MDR reversal and pro-apoptotic effects of statins and statins combined with flavonoids in colon cancer cells

The resistance of cancer cells to a variety of structurally non-related cytotoxic drugs is known as multidrug resistance phenomenon (MDR). In cellular membranes an activity of MDR transporters such as P-glycoprotein (ABCB1) is affected by their lipid environment. Many various compounds have been examined for their ability to restore drug-sensitivity of resistant cancer cells. Statins, inhibitors of the key enzyme of mevalonate pathway HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase are drugs commonly prescribed in order to reduce serum level of cholesterol and to diminish the risk of cardiovascular disease. Statins as drugs that influence lipid composition of cell membrane and in that way they also exert influence on lipid bilayer properties appear to be good candidates as MDR modulators. In this work it was shown that statins - mevastatin and simvastatin exert antiproliferative, pro-apoptotic and reversing drug resistance effect in human colon adenocarcinoma cell line LoVo and its drug-resistant subline LoVo/Dx. A hypothesis was also checked whether flavones, which as it is well known are able to influence the biosynthesis of cholesterol, may change the anticancer activity of statins. Our investigations have revealed that combined use of statins and studied flavonoids results in enhanced cell growth inhibition and apoptosis and lower cancer cell proliferation as compared to the application only statins alone. Moreover, in drug resistant LoVo/Dx cells a stronger decrease of resistance to doxorubicine was observed in the presence of statins in combination with flavones as compared to the effect observed for statins only.

Inhibition of cholesterol biosynthesis overcomes enzalutamide resistance in castration-resistant prostate cancer (CRPC)

Enzalutamide, a nonsteroidal second-generation antiandrogen, has been recently approved for the management of castration-resistant prostate cancer (CRPC). Although patients can benefit from enzalutamide at the beginning of this therapy, acquired enzalutamide resistance usually occurs within a short period. This motivated us to investigate the mechanism involved and possible approaches for overcoming enzalutamide resistance in CRPC. In the present study, we found that 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), a crucial enzyme in the mevalonate pathway for sterol biosynthesis, is elevated in enzalutamide-resistant prostate cancer cell lines. HMGCR knockdown could resensitize these cells to the drug, and HMGCR overexpression conferred resistance to it, suggesting that aberrant HMGCR expression is an important enzalutamide-resistance mechanism in prostate cancer cells. Furthermore, enzalutamide-resistant prostate cancer cells were more sensitive to statins, which are HMGCR inhibitors. Of note, a combination of simvastatin and enzalutamide significantly inhibited the growth of enzalutamide-resistant prostate cancer cells in vitro and tumors in vivo Mechanistically, simvastatin decreased protein levels of the androgen receptor (AR), which was further reduced in combination with enzalutamide. We observed that the decrease in AR may occur through simvastatin-mediated inhibition of the mTOR pathway, whose activation was associated with increased HMGCR and AR expression. These results indicate that simvastatin enhances the efficacy of enzalutamide-based therapy, highlighting the therapeutic potential of statins to overcome enzalutamide resistance in CRPC.

The effects of metformin and simvastatin on the growth of LNCaP and RWPE-1 prostate epithelial cell lines

The anti-diabetic drug metformin and cholesterol-lowering statins inhibit prostate cancer cell growth in vitro and have been linked with lowered risk of prostate cancer in epidemiological studies. We evaluated the effects of these drugs on cancerous and non-cancerous prostate epithelial cell lines. Cancer (LNCaP) and normal (RWPE-1) prostate epithelial cell lines were treated with pharmacologic concentrations of metformin and simvastatin alone and in combinations. Relative changes in cell number were measured with crystal violet staining method. Drug effects on apoptosis and cell cycle were measured with flow cytometry. We also measured changes in the activation and expression of a set of reported target proteins of metformin and statins with Western blotting. Metformin decreased the relative cell number of LNCaP cells by inducing G1 cell cycle block, autophagy and apoptosis, and slightly increased cytosolic ATP levels, whereas RWPE-1 cells were resistant to metformin. However, RWPE-1 cells were sensitive to simvastatin, which induced G2 cell cycle block, autophagy and apoptosis, and increased cytosolic ATP levels in these cells. Combination of metformin and simvastatin synergistically decreased cytosolic ATP levels, increased autophagy and instead of apoptosis, induced necrosis in LNCaP cells. Synergistic effects were not observed in RWPE-1 cells. These results suggest, that prostate cancer cells may be more vulnerable to combined growth-inhibiting effects of metformin and simvastatin compared to normal cells. The data presented here provide evidence for the potency of combined metformin and statin, also at pharmacologic concentrations, as a chemotherapeutic option for prostate cancer.

Equol inhibits prostate cancer growth through degradation of androgen receptor by S-phase kinase-associated protein 2

Chemopreventive and potential therapeutic effects of soy isoflavones have been shown to be effective in numerous preclinical studies as well as clinical studies in prostate cancer. Although the inhibition of androgen receptor signaling has been supposed as one mechanism underlying their effects, the precise mechanism of androgen receptor inhibition remains unclear. Thus, this study aimed to clarify their mechanism. Among soy isoflavones, equol suppressed androgen receptor as well as prostate-specific antigen expression most potently in androgen-dependent LNCaP cells. However, the inhibitory effect on androgen receptor expression and activity was less prominent in castration-resistant CxR and 22Rv1 cells. Consistently, cell proliferation was suppressed and cellular apoptosis was induced by equol in LNCaP cells, but less so in CxR and 22Rv1 cells. We revealed that the proteasome pathway through S-phase kinase-associated protein 2 (Skp2) was responsible for androgen receptor suppression. Taken together, soy isoflavones, especially equol, appear to be promising as chemopreventive and therapeutic agents for prostate cancer based on the fact that equol augments Skp2-mediated androgen receptor degradation. Moreover, because Skp2 expression was indicated to be crucial for the effect of soy isoflavones, soy isoflavones may be applicable for precancerous and cancerous prostates.

Simvastatin blocks TGF-β1-induced epithelial-mesenchymal transition in human prostate cancer cells

In recent years, the use of statins has been reported to be associated with a reduced risk of prostate cancer (PCa), particularly metastatic PCa. The mechanisms underlying these epidemiological observations are poorly understood. Epithelial-mesenchymal transition (EMT) is a critical initial step and a hallmark for cancer metastasis. In the present study, the relationship between simvastatin and EMT in PCa and the mechanism involved was investigated. It was demonstrated that simvastatin inhibited the EMT as assessed by reduced expression of N-cadherin and vimentin, and increased E-cadherin in TGF-β1 treated DU145 PCa cells. Furthermore, simvastatin inhibited TGF-β1-induced migration and invasion of DU145 cells. The TGF-β1/Smad pathway and non-Smad pathway were investigated in simvastatin-treated DU145 cells. Simvastatin had no effect on TGF-β1-induced phosphorylation of Smad2 and Smad3. In the non-Smad pathway, simvastatin reduced TGF-β1-induced p38 MAPK phosphorylation, but had no effect on TGF-β1-induced Erk1/2 phosphorylation. Simvastatin attenuated TGF-β1-induced EMT, cell migration and invasion in DU145 cells. These effects may have been mediated by the inhibition of p38 MAPK phosphorylation, not through the canonical Smad pathway. Therefore simvastatin may be a promising therapeutic agent for treating PCa.

Effects of statin use on the response duration to androgen deprivation therapy in metastatic prostate cancer

Purpose

To determine whether statin use delays the development of castration-resistant prostate cancer (CRPC) in patients with metastatic prostate cancer treated with androgen deprivation therapy (ADT).

Materials and Methods

A total of 171 patients with metastatic prostate cancer at the time of diagnosis who were treated with ADT between January 1997 and December 2013 were retrospectively analyzed. The patients were classified into two groups: the nonstatin use group (A group) and the statin use group (B group). Multivariate analysis was performed on statin use and other factors considered likely to have an effect on the time to progression to CRPC.

Results

The mean patient age was 67.1±9.1 years, and the mean follow-up period was 52 months. The mean initial prostate-specific antigen (PSA) level was 537 ng/mL. Of the 171 patients, 125 (73%) were in group A and 46 (27%) were in group B. The time to progression to CRPC was 22.7 months in group A and 30.5 months in group B, and this difference was significant (p=0.032). Blood cholesterol and initial PSA levels did not differ significantly according to the time to progression to CRPC (p=0.288, p=0.198). Multivariate analysis using the Cox regression method showed that not having diabetes (p=0.037) and using a statin (p=0.045) significantly increased the odds ratio of a longer progression to CRPC.

Conclusions

Statin use in metastatic prostate cancer patients appears to delay the progression to CRPC. Large-scale, long-term follow-up studies are needed to validate this finding.

Statin Use Reduces Prostate Cancer All-Cause Mortality: A Nationwide Population-Based Cohort Study

Studies have suggested that statin use is related to cancer risk and prostate cancer mortality. We conducted a population-based cohort study to determine whether using statins in prostate cancer patients is associated with reduced all-cause mortality rates. Data were obtained from the Taiwan National Health Insurance Research Database. The study cohort comprised 5179 patients diagnosed with prostate cancer who used statins for at least 6 months between January 1, 1998 and December 31, 2010. To form a comparison group, each patient was randomly frequency-matched (according to age and index date) with a prostate cancer patient who did not use any type of statin-based drugs during the study period. The study endpoint was mortality. The hazard ratio (HR) and 95% confidence interval (CI) were estimated using Cox regression models. Among prostate cancer patients, statin use was associated with significantly decreased all-cause mortality (adjusted HR = 0.65; 95% CI = 0.60-0.71). This phenomenon was observed among various types of statin, age groups, and treatment methods. Analyzing the defined daily dose of statins indicated that both low- and high-dose groups exhibited significantly decreased death rates compared with nonusers, suggesting a dose-response relationship. The results of this population-based cohort study suggest that using statins reduces all-cause mortality among prostate cancer patients, and a dose-response relationship may exist.

Impact of cholesterol on disease progression

Cholesterol-rich microdomains (also called lipid rafts), where platforms for signaling are provided and thought to be associated with microbe-induced pathogenesis and lead to cancer progression. After treatment of cells with cholesterol disrupting or usurping agents, raft-associated proteins and lipids can be dissociated, and this renders the cell structure nonfunctional and therefore mitigates disease severity. This review focuses on the role of cholesterol in disease progression including cancer development and infectious diseases. Understanding the molecular mechanisms of cholesterol in these diseases may provide insight into the development of novel strategies for controlling these diseases in clinical scenarios.

Inhibition of the mevalonate pathway affects epigenetic regulation in cancer cells

The mevalonate pathway provides metabolites for post-translational modifications such as farnesylation, which are critical for the activity of RAS downstream signaling. Subsequently occurring regulatory processes can induce an aberrant stimulation of DNA methyltransferase (DNMT1) as well as changes in histone deacetylases (HDACs) and microRNAs in many cancer cell lines. Inhibitors of the mevalonate pathway are increasingly recognized as anticancer drugs. Extensive evidence indicates an intense cross-talk between signaling pathways, which affect growth, differentiation, and apoptosis either directly or indirectly via epigenetic mechanisms. Herein, we show data obtained by novel transcriptomic and corresponding methylomic or proteomic analyses from cell lines treated with pharmacologic doses of respective inhibitors (i.e., simvastatin, ibandronate). Metabolic pathways and their epigenetic consequences appear to be affected by a changed concentration of NADPH. Moreover, since the mevalonate metabolism is part of a signaling network, including vitamin D metabolism or fatty acid synthesis, the epigenetic activity of associated pathways is also presented. This emphasizes the far-reaching epigenetic impact of metabolic therapies on cancer cells and provides some explanation for clinical observations, which indicate the anticancer activity of statins and bisphosphonates.

Statin use not associated with improved outcomes in patients treated with brachytherapy for prostate cancer

PURPOSE

To investigate the association between statin use and prostate cancer outcomes in intermediate- and high-risk patients treated with brachytherapy for prostate cancer.

METHODS AND MATERIALS

Between 1998 and 2010, 754 men with National Comprehensive Cancer Network intermediate- (n = 627) and high-risk (n = 127) prostate cancer were treated with prostate brachytherapy at our institution. Patients received either low-dose-rate or high-dose-rate brachytherapy as monotherapy or in combination with supplemental external beam radiotherapy. Two hundred eighty-five patients (37.8%) also received androgen-deprivation therapy. Two hundred seventy-three men (36.2%) were identified as taking statin medication before initiating radiation therapy. Prostate-specific antigen relapse-free survival (PSA-RFS), distant metastasis-free survival (DMFS), and overall survival were compared using log-rank tests. Associations of patient and treatment characteristics with outcomes were analyzed with univariate and multivariate regression. The median followup was 48 months.

RESULTS

The 8-year PSA-RFS for intermediate-risk, high-risk, and all patients was 92.2%, 64.1%, and 87.7%, respectively. The 8-year DMFS was 97.1%, 82.9%, and 94.9%, respectively. The 8-year overall survival for the entire cohort was 86.6%. There were no significant differences between statin users and nonusers when stratified by risk group, nor when analyzed as a full cohort. On multivariate analysis, Gleason score 4 + 3 = 7 and >7 were significantly associated with worse PSA-RFS (p ≤ 0.003 and <0.001, respectively). Gleason score > 7 (p = 0.008) and the use of neoadjuvant androgen-deprivation therapy (p = 0.03) was associated with worse DMFS. Statin use did not significantly impact PSA-RFS or DMFS.

CONCLUSIONS

Pretreatment statin use is not associated with improved outcomes in intermediate- and high-risk patients undergoing prostate brachytherapy-based regimens for prostate cancer.

PMA induces androgen receptor downregulation and cellular apoptosis in prostate cancer cells

Phorbol 12-myristate 13-acetate (PMA) induces cellular apoptosis in prostate cancer cells, the growth of which is governed by androgen/androgen receptor (AR) signaling, but the mechanism by which PMA exerts this effect remains unknown. Therefore, in this study, we investigated the mechanistic action of PMA in prostate cancer cells with regard to AR. We showed that PMA decreased E2F1 as well as AR expression in androgen-dependent prostate cancer LNCaP cells. Furthermore, PMA activated JNK and p53 signaling, resulting in the induction of cellular apoptosis. In LNCaP cells, androgen deprivation and a novel anti-androgen enzalutamide (MDV3100) augmented cellular apoptosis induced by PMA. Moreover, castration-resistant prostate cancer (CRPC) C4-2 cells were more sensitive to PMA compared with LNCaP cells and were sensitized to PMA by enzalutamide. Finally, the expression of PKC, E2F1, and AR was diminished in PMA-resistant cells, indicating that the gain of independence from PKC, E2F1, and AR functions leads to PMA resistance. In conclusion, PMA exerted its anti-cancer effects via the activation of pro-apoptotic JNK/p53 and inhibition of pro-proliferative E2F1/AR in prostate cancer cells including CRPC cells. The therapeutic effects of PMA were augmented by androgen deletion and enzalutamide in androgen-dependent prostate cancer cells, as well as by enzalutamide in castration-resistant cells. Taken together, PMA derivatives may be promising therapeutic agents for treating prostate cancer patients including CRPC patients.

Novel prospects of statins as therapeutic agents in cancer

Statins are well known competitive inhibitors of hydroxymethylglutaryl-CoA reductase enzyme (HMG-CoA reductase), thus traditionally used as cholesterol-lowering agents. In recent years, more and more effects of statins have been revealed. Nowadays alterations of lipid metabolism have been increasingly recognized as a hallmark of cancer cells. Consequently, much attention has been directed toward the potential of statins as therapeutic agents in the oncological field. Accumulated in vitro and in vivo clinical evidence point out the role of statins in a variety of human malignancies, in regulating tumor cell growth and anti-tumor immune response. Herein, we summarize and discuss, in light of the most recent observations, the anti-tumor effects of statins, underpinning the detailed mode of action and looking for their true significance in cancer prevention and treatment, to determine if and in which case statin repositioning could be really justified for neoplastic diseases.

Statins: protectors or pretenders in prostate cancer?

The role of statin therapy in prostate cancer (PCa) prevention and treatment is plagued by controversy. This critical review of published clinical series reveals several caveats in earlier studies, which reported no benefit. Recent studies that adjust for confounding factors have demonstrated statin therapy to be associated with PCa prevention and favorable clinical outcomes. Developed as inhibitors of cholesterol synthesis, the expected mechanism of statin action is systemic cholesterol reduction. By lowering circulating cholesterol, statins indirectly reduce cellular cholesterol levels in multiple cell types, impacting on membrane microdomains and steroidogenesis. Although non-cholesterol mechanisms of statin action have been proposed, they are limited by the uncertainties surrounding in vivo tissue statin concentrations.

Does Statin or ASA Affect Survival When Prostate Cancer Is Treated with External Beam Radiation Therapy?

Background. Prior studies evaluating the effect of statins or acetylsalicylic acid (ASA) on the survival of men receiving prostate cancer were treatment have reported conflicting results, and have not adjusted for comorbidity. Our aim is to investigate the influence of statins and ASA on prostate cancer survival, when comorbidity is adjusted for, in men treated with external beam radiation therapy (EBRT) for prostate cancer. Methods. A cohort of 3851 patients with prostate cancer treated with curative EBRT ± androgen deprivation therapy (ADT) between 2000 and 2007. Stage, treatment, medication use, and Charlson comorbidity index (CCI) scores were analyzed. Results. Median followup was 8.4 years. Mean age was 70.3 years. Neoadjuvant ADT was used in 67%. Statins were used in 23%, ASA in 24%, and both in 11%. Comorbidity scores were 0 in 65%, 1 in 25%, and ≥2 in 10% of patients. Statin and ASA use were associated with increased age and comorbidity. Although statin and ASA use were significantly associated with improved prostate cancer specific survival (PCSS) on univariate analysis, neither were on multivariate analysis. Conclusion. Neither statin nor ASA use impacted PCSS on multivariate competing risks analysis. Survival was impacted by increased comorbidity as well as statin and ASA use.

Effects of long-term atorvastatin treatment on cardiac aging

A number of studies have reported that atorvastatin (AVT) may have an important role in the delay of cardiac aging. However, the mechanism by which AVT affects cardiac aging has not been established. In this study, a series of experiments were performed to investigate the effects of AVT treatment on the cardiovascular system and the associated mechanism. Wistar rats were administered AVT or saline for 4 months. Age-related changes in the hearts were measured at the end of the experiment. The results showed that compared with young rats, the aged rats had significant changes indicative of myocardial aging, including increased blood lipid 1evelss, increased body weight, cardiac hypertrophy, larger myocardial cells, irregular muscle fibers, fewer deeply stained nuclei, smaller intercellular spaces, a larger number of apoptotic cells and increased levels of lipofuscin in myocardial tissue. However, long-term AVT treatment was able to significantly delay or even reverse these aging-related changes. In addition, these effects showed a certain dose-dependence. In general, long-term AVT treatment reduces blood lipids, inhibits cardiac hypertrophy, suppresses cardiomyocyte apoptosis and lowers the level of oxidative stress to protect the heart from aging.

Pathological characteristics, biochemical recurrence and functional outcome in radical prostatectomy patients on statin therapy

INTRODUCTION

We assessed the pathological characteristics of the radical prostatectomy specimen, the rate of biochemical failure and the functional outcome after surgery, in terms of incontinence and erectile dysfunction rate, in patients on statin medication.

MATERIALS AND METHODS

A total of 588 patients with a mean age 65.2 years (SD = 5.7 years) participated in the study. All patients were contacted and interviewed.

RESULTS

Users who had been on statin medication for more than 2 years had lower levels of preoperative serum PSA (p = 0.034), a 2.76 times greater likelihood of being staged as pT3a to pT3b rather than pT2a to pT2c, and a 5.39 times greater likelihood of having a postoperative Gleason score equal to seven or more. Positive surgical margins and urinary incontinence were not significantly associated with statin use. The probability of erectile dysfunction was significantly greater for statin users.

CONCLUSION

Statin medication was associated with a statistically significantly lower PSA value and an increased rate of high Gleason score and pathologic stage in patients receiving medication for more than 2 years. Statins were found to be an independent predictor of recurrence. Lastly, statin users were more likely to present with preoperative and postoperative erectile dysfunction.

Inhibition of the insulin-like growth factor-1 receptor enhances effects of simvastatin on prostate cancer cells in co-culture with bone

Prostate cancer (PC) bone metastases show weak responses to conventional therapies. Bone matrix is rich in growth factors, with insulin-like growth factor-1 (IGF-1) being one of the most abundant. IGF-1 acts as a survival factor for tumor cells and we speculate that bone-derived IGF-1 counteracts effects of therapies aimed to target bone metastases and, consequently, that therapeutic effects could be enhanced if given in combination with IGF-1 receptor (IGF-1R) inhibitors. Simvastatin inhibits the mevalonate pathway and has been found to induce apoptosis of PC cells. The aims of this study were to confirm stimulating effects of bone-derived IGF-1 on PC cells and to test if IGF-1R inhibition enhances growth inhibitory effects of simvastatin on PC cells in a bone microenvironment. The PC-3 and 22Rv1 tumor cell lines showed significantly induced cell growth when co-cultured with neonatal mouse calvarial bones. The tumor cell IGF-1R was activated by calvariae-conditioned media and neutralization of bone-derived IGF-1 abolished the calvarium-induced PC-3 cell growth. Treatment of PC-3 and 22Rv1 cells with simvastatin, or the IGF-1R inhibitor NVP-AEW541, reduced tumor cell numbers and viability, and induced apoptosis. Combined simvastatin and NVP-AEW541 treatment resulted in enhanced growth inhibitory effects compared to either drug given alone. Effects of simvastatin involved down-regulation of IGF-1R in PC-3 and of constitutively active androgen receptor variants in 22Rv1 cells. In conclusion, we suggest that IGF-1 inhibition may be a way to strengthen effects of apoptosis-inducing therapies on PC bone metastases; a possibility that needs to be further tested in pre-clinical models.

Association between use of β-blockers and prostate cancer-specific survival: a cohort study of 3561 prostate cancer patients with high-risk or metastatic disease

BACKGROUND

We recently reported reduced prostate cancer (PCa)-specific mortality for β-blocker users among patients receiving androgen-deprivation therapy in a health survey cohort including 655 PCa patients. Information on clinical characteristics was limited.

OBJECTIVE

To assess the association between β-blockers and PCa-specific mortality in a cohort of 3561 prostate cancer patients with high-risk or metastatic disease, and to address potential confounding from the use of statins or acetylsalicylic acid (ASA).

DESIGN, SETTING, AND PARTICIPANTS

Clinical information from all men reported to the Cancer Registry of Norway with a PCa diagnosis between 2004 and 2009 (n=24 571) was coupled with information on filled prescriptions between 2004 and 2011 from the Norwegian Prescription Database. Exclusion criteria were low- or intermediate-risk disease; planned radiotherapy or radical prostatectomy; initiation of β-blocker, ASA, or statin use after diagnosis where applicable; missing information on baseline Gleason score, prostate-specific antigen level, T stage or performance status; and missing follow-up.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cox proportional hazards modelling and competing risk regression modelling were used to analyse the effects of β-blocker use on all-cause and PCa-specific mortality, respectively. Differences between β-blocker users and nonusers regarding baseline clinical characteristics were assessed by the Wilcoxon-Mann-Whitney U test, Pearson chi-square test, and Student t test.

RESULTS AND LIMITATIONS

Median follow-up was 39 mo. β-Blocker use was associated with reduced PCa mortality (adjusted subhazard ratio: 0.79; 95% confidence interval [CI], 0.68-0.91; p value: 0.001). The observed reduction in PCa mortality was independent of the use of statins or ASA. We observed no association with all-cause mortality (adjusted hazard ratio: 0.92; 95% CI, 0.83-1.02). The main limitations of the study were the observational study design and short follow-up.

CONCLUSIONS

β-Blocker use was associated with reduced PCa-specific mortality in patients with high-risk or metastatic disease at the time of diagnosis. Our findings need validation from further observational studies.

Pro-survival and anti-apoptotic properties of androgen receptor signaling by oxidative stress promote treatment resistance in prostate cancer

Oxidative stress caused by an increase in reactive oxygen species levels or a decrease in cellular antioxidant capacity can evoke the modulation of various cellular events including androgen receptor (AR) signaling via direct or indirect interactions. In this review, we summarize the mechanisms of AR activation by oxidative stress including: i) AR overexpression; ii) AR activation by AR co-regulators or intracellular signal transduction pathways; iii) generation of AR mutations or splice variants; and iv) de novo androgen synthesis. AR signaling augmented by oxidative stress appears to contribute to pro-survival and anti-apoptotic effects in prostate cancer cells in response to androgen deprivation therapy. In addition, AR signaling suppresses anti-survival and pro-apoptotic effects in prostate cancer cells in response to various cytotoxic and tumor-suppressive interventions including taxanes and radiation through the modulation of βIII-tubulin and ataxia telangiectasia-mutated kinase expression respectively. Taken together, AR signaling appears to render prostate cancer cells refractory to various therapeutic interventions including castration, taxanes, and radiation, indicating that AR signaling is a comprehensive resistant factor and crucial target for prostate cancer treatment.

Phospholipase PLA2G7, associated with aggressive prostate cancer, promotes prostate cancer cell migration and invasion and is inhibited by statins

Prostate cancer is the second leading cause of cancer mortality in men in developed countries. Due to the heterogeneous nature of the disease, design of novel personalized treatments is required to achieve efficient therapeutic responses. We have recently identified phospholipase 2 group VII (PLA2G7) as a potential drug target especially in ERG oncogene positive prostate cancers. Here, the expression profile of PLA2G7 was studied in 1137 prostate cancer and 409 adjacent non-malignant prostate tissues using immunohistochemistry to validate its biomarker potential and putative association with disease progression. In order to reveal the molecular alterations induced by PLA2G7 impairment, lipidomic and gene expression profiling was performed in response to PLA2G7 silencing in cultured prostate cancer cells. Moreover, the antineoplastic effect of statins combined with PLA2G7 impairment was studied in prostate cancer cells to evaluate the potential of repositioning of in vivo compatible drugs developed for other indications towards anti-cancer purposes. The results indicated that PLA2G7 is a cancer-selective biomarker in 50% of prostate cancers and associates with aggressive disease. The alterations induced by PLA2G7 silencing highlighted the potential of PLA2G7 inhibition as an anti-proliferative, pro-apoptotic and anti-migratorial therapeutic approach in prostate cancer. Moreover, the anti-proliferative effect of PLA2G7 silencing was potentiated by lipid-lowering statins in prostate cancer cells. Taken together, our results support the potential of PLA2G7 as a biomarker and a drug target in prostate cancer and present a rationale for combining PLA2G7 inhibition with the use of statins in prostate cancer management.

[Is statin use associated with D'Amico risk groups and biochemical recurrence after radical prostatectomy?]

OBJECTIVE

To examine the association between statin use and prostate cancer (PC) stratified with D'Amico risk groups and biochemical recurrence (BR) in patients undergoing radical prostatectomy (RP).

PATIENTS AND METHODS

All medical charts of patients managed from 2004 to 2008 for PC with RP were reviewed retrospectively. The use and the type of statin were identified. Patients were split according to the use (S+) or not (S-) of statin. The two groups were compared using the Chi(2) test. A logistic regression was performed for multivariate analysis.

RESULTS

Overall, 377 patients were included. Mean age was 64 (48-76) (median, range). Ninety-seven patients (27.5%) used statin for at least a year. Groups S- and S+ were comparable in terms of age, obesity, diabetes, preoperative PSA, biopsy Gleason score or clinical stage. The use of statin was statistically associated with D'Amico risk groups (P=0.003). The number of high-risk PC was higher in Group S+ (23.7% vs. 10.7%) with an odds ratio of 2.4 (P=0.009). With a mean follow up of 33±10 months, the overall 2-years-BR was 89%. The 2-years-BR was higher in the S+ (93% vs. 88%, P=0.16). After adjustment, this difference was statistically significant with a hazard ratio of 0.46 (P=0.036).

CONCLUSION

The use of statin was associated with high risk PC in this study. Surprisingly, the statin use seem also to be associated with better disease-free survival, independently of other risk factors.

Activation of androgen receptor, lipogenesis, and oxidative stress converged by SREBP-1 is responsible for regulating growth and progression of prostate cancer cells

We previously reported that sterol regulatory element-binding protein-1 (SREBP-1) is involved in the transcriptional regulation of androgen receptor (AR) and formation of fatty acid through altered expression of fatty acid synthase (FASN). In this article, we provide a new finding that SREBP-1 induced oxidative stress in prostate cancer cells through increased production of reactive oxygen species (ROS) and expression of NADPH oxidase 5 (Nox5). We have shown that (i) expression of SREBP-1 protein is positively associated with the clinical Gleason grades in human prostate cancer; (ii) genetic overexpression or knockdown of SREBP-1 in prostate cancer cells resulted in corresponding increased or decreased AR, FASN and Nox5 expression, fatty acid and lipid droplet accumulation, and ROS generation; and (iii) SREBP-1 induces and promotes the growth, migration, invasion, and castration-resistant progression of prostate cancer cells in vitro and in vivo. Our data show a novel molecular mechanism by which SREBP-1 promotes prostate cancer growth and progression through alterations in the concerted intracellular metabolic and signaling networks involving AR, lipogenesis, and ROS in prostate cancer cells.

Y-box binding protein-1 promotes castration-resistant prostate cancer growth via androgen receptor expression

The androgen receptor (AR) is well known to play a central role in the pathogenesis of prostate cancer (PCa). In several studies, AR was overexpressed in castration-resistant PCa (CRPC). However, the mechanism of AR overexpression in CRPC is not fully elucidated. Y-box binding protein-1 (YB-1) is a pleiotropic transcription factor that is upregulated in CPRC. We aimed to elucidate the role of YB-1 in castration resistance of PCa and identify therapeutic potential of targeting YB-1. Using immunohistochemistry, we found that nuclear YB-1 expression significantly correlated with the Gleason score and AR expression in PCa tissues. In PCa cells, YB-1 regulated AR expression at the transcriptional level. Furthermore, YB-1 expression and nuclear localization were upregulated in CRPC cells. Overexpression of AR, as well as YB-1, conferred castration-resistant growth in LNCaP and 22Rv1 cells. Conversely, knocking down YB-1 resulted in suppressed cell growth and induced apoptosis, which was more efficient than knocking down AR in LNCaP cells. In other types of PCa cells, such as CRPC cells, knocking down YB-1 resulted in a significant reduction of cell growth. In conclusion, these findings suggested that YB-1 induces castration resistance in androgen-dependent PCa cells via AR expression. Thus, YB-1 may be a promising therapeutic target for PCa, as well as CRPC.

Anticancer efficacy of simvastatin on prostate cancer cells and tumor xenografts is associated with inhibition of Akt and reduced prostate-specific antigen expression

Prostate cancer is the second-leading cause of cancer-associated death among men in the United States. There has been renewed interest in the potential therapeutic benefits of statins for cancer. Simvastatin, a widely used generic drug for preventing cardiovascular events, is well known for its effects on cellular proliferation and inflammation, two key processes that also determine the rate of tumor growth. Although a growing body of evidence suggests that statins have the potential to reduce the risk of many cancers, there are discrepancies over the pro- and anticancer effects of statins. In the current study, we sought to investigate the effects of simvastatin on the Akt pathway in prostate cancer cells with respect to the regulation of various cell functions in vitro and tumor growth in vivo. Time- and dose-dependent effects of simvastatin on LNCaP (androgen-dependent) and PC3 (androgen-independent) cells indicate that treatment with simvastatin at concentrations as low as 25 μM was sufficient to inhibit serum-stimulated Akt activity. Akin to this, treatment with simvastatin significantly inhibited serum-induced cell migration, invasion, colony formation, and proliferation. Simvastatin-mediated effects on colony formation were rescued by adenovirus-mediated expression of constitutively active Akt (myristoylated Akt) in PC3 cell lines. A PC3 xenograft model performed in nude mice exhibited reduced tumor growth with simvastatin treatment associated with decreased Akt activity and reduced prostate-specific antigen (PSA) levels. Our findings demonstrate the therapeutic benefits of simvastatin for prostate cancer and suggest a link between simvastatin, regulation of Akt activity, and PSA expression in prostate tumors.