Statins and prostate cancer prevention: where we are now, and future directions

Association between genetically proxied HMGCR inhibition and male reproductive health: A Mendelian randomization study

BACKGROUND

The causal associations between statin use and male sex hormone levels and related disorders have not been fully understood. In this study, we employed Mendelian randomization for the first time to investigate these associations.

METHODS

In two-sample Mendelian randomization framework, genetic proxies for hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) inhibition were identified as variants in the HMGCR gene that were associated with both levels of gene expression and low density lipoprotein cholesterol (LDL-C). We assessed the causal relationship between HMGCR inhibitor and 5 sex hormone levels/2 male-related diseases. Additionally, we investigated the association between 4 circulating lipid traits and outcomes. The "inverse variance weighting" method was used as the primary approach, and we assessed for potential heterogeneity and pleiotropy. In a secondary analysis, we revalidated the impact of HMGCR on 7 major outcomes using the summary-data-based Mendelian randomization method.

RESULTS

Our study found a significant causal association between genetic proxies for HMGCR inhibitor and decreased levels of total testosterone (TT) (LDL-C per standard deviation = 38.7mg/dL, effect = -0.20, 95% confidence interval [CI] = -0.25 to -0.15) and bioavailable testosterone (BT) (effect = -0.15, 95% CI = -0.21 to -0.10). Obesity-related factors were found to mediate this association. Furthermore, the inhibitor were found to mediate a reduced risk of prostate cancer (odds ratio = 0.81, 95%CI = 0.7-0.93) by lowering bioavailable testosterone levels, without increasing the risk of erectile dysfunction (P = .17). On the other hand, there was a causal association between increased levels of LDL-C, total cholesterol, triglycerides (TG) and decreased levels of TT, sex hormone-binding globulin, and estradiol.

CONCLUSIONS

The use of HMGCR inhibitor will reduce testosterone levels and the risk of prostate cancer without the side effect of erectile dysfunction. LDL-C, total cholesterol, and TG levels were protective factors for TT, sex hormone-binding globulin, and estradiol.

Influence of statins in metastatic castration-resistant prostate cancer patients treated with new antiandrogen therapies: a systematic review and meta-analysis

Objective

To evaluate whether the addition of statins to the new antiandrogens (enzalutamide or abiraterone) affects overall survival in patients with metastatic castration-resistant prostate cancer.

Methods

We searched studies in English language including the keywords statins, overall survival, and metastatic castration-resistant prostate cancer, at PubMed^® (MEDLINE^®), Embase and Cochrane databases.

Results

A total of 195 articles were initially identified, but only four met the inclusion criteria and were selected for the meta-analysis. A total of 955 patients, 632 on the new antiandrogens only group, and 323 on the new antiandrogens + statins group, were analyzed. In all four studies the combination therapy (new antiandrogens + statin) was well tolerated, regardless of which new antiandrogens were used. Neither the type of statin nor the doses and duration of use were well specified in the studies. The combination therapy in metastatic castration-resistant prostate cancer was associated with an overall survival improvement, and a 46% reduction in death (hazard ratio of 0.54; 95%CI 0.34-0.87; p<0.01) in multivariate analysis.

Conclusion

There seems to be a clinical benefit with the association of statins to the new antiandrogens in patients with metastatic castration-resistant prostate cancer, suggesting longer overall survival with no important collateral effect. However, due to fragility of the studies available in the literature, we are not yet capable of recommending this combination of drugs in the clinical practice. Further randomized prospective studies are warranted to confirm these beneficial outcomes.

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.

SHH-N non-canonically sustains androgen receptor activity in androgen-independent prostate cancer cells

Prostate cancer is the second most frequent cancer diagnosed in men worldwide. Localized disease can be successfully treated, but advanced cases are more problematic. After initial effectiveness of androgen deprivation therapy, resistance quickly occurs. Therefore, we aimed to investigate the role of Hedgehog-GLI (HH-GLI) signaling in sustaining androgen-independent growth of prostate cancer cells. We found various modes of HH-GLI signaling activation in prostate cancer cells depending on androgen availability. When androgen was not deprived, we found evidence of non-canonical SMO signaling through the SRC kinase. After short-term androgen deprivation canonical HH-GLI signaling was activated, but we found little evidence of canonical HH-GLI signaling activity in androgen-independent prostate cancer cells. We show that in androgen-independent cells the pathway ligand, SHH-N, non-canonically binds to the androgen receptor through its cholesterol modification. Inhibition of this interaction leads to androgen receptor signaling downregulation. This implies that SHH-N activates the androgen receptor and sustains androgen-independence. Targeting this interaction might prove to be a valuable strategy for advanced prostate cancer treatment. Also, other non-canonical aspects of this signaling pathway should be investigated in more detail and considered when developing potential therapies.

Serum lipids and prostate cancer

BACKGROUND

Conflicting results are found in the literature relating serum lipids levels and prostate cancer. Some results imply a relationship between them; others contradict this association. The purpose of this study was to investigate a possible association between serum lipids levels and prostate cancer, at time of diagnosis.

METHODS

We measured serum levels of total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides in 237 patients submitted to a prostate biopsy, with PSA between 2 and 10 ng/ml. Patients without cancer at biopsy were used as controls, and the others were considered as cases. No information about lipid-lowering therapy, including statins, was available neither in cases nor in controls. Cases were divided into risk groups, according to the disease severity, based on staging. Lipids levels were compared between groups, using parametric and nonparametric tests. Logistic regression analysis and odds ratios were calculated.

RESULTS

LDL and total cholesterol levels were lower in patients with cancer, with the difference being statistically significant for LDL cholesterol (p = 0.010) and borderline for total cholesterol (p = 0.050). No significant differences were found between the several risk groups. Odds ratios for low LDL cholesterol (<130 mg/dl) and low total cholesterol (<200 mg/dl), with prostate cancer as the outcome, were 1.983 and 1.703, respectively. There were no significant differences between cases and controls for the other lipids.

CONCLUSION

Lower LDL cholesterol (<130 mg/dl) and lower total cholesterol (<200 mg/dl) serum levels seem to associate with prostate cancer, at time of diagnosis.

Association of statin use with risk of Gleason score-specific prostate cancer: A hospital-based cohort study

BACKGROUND

Conflicting evidence suggests that statins act chemopreventively against prostate cancer (PCa). Whether the association of statin use with PCa risk is Gleason score-dependent, time-, dose-respondent is not well studied.

METHODS

We conducted a cohort study at a tertiary hospital in the Southeastern US using longitudinal data of electronic medical records (EMR) from 1994 to 2016. Only cancer-free men aged >18 years at baseline with follow-up time of ≥12 months were included. Time-dependent Cox proportional hazards regression was used to estimate adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs).

RESULTS

Among 13 065 men, 2976 were diagnosed with PCa over median follow-up of 6.6 years. Statin use was associated with lower risk of both Gleason low- (score <7: aHR, 0.85; 95% CI, 0.74-0.96) and high-grade PCa (score ≥7: aHR, 0.54; 95% CI, 0.42-0.69). The protective association was observed only when statins had been used for a relatively longer duration (≥11 months) or higher dose (≥121 defined daily doses), and were more pronounced for PCa of higher Gleason score (<7: aHR, 0.85, 95% CI, 0.74-0.96; 7 [3 + 4]: aHR, 0.62, 95% CI, 0.43-0.90; 7 [4 + 3]: aHR, 0.49, 95% CI, 0.29-0.82; 8: aHR, 0.60, 95% CI, 0.37-0.96; 9-10: aHR, 0.24, 95% CI, 0.11-0.54). Lipophilic statins (aHR, 0.83; 95% CI, 0.72-0.95) might be more protective than hydrophilic statins (aHR, 0.91, 95% CI, 0.63-1.33) against PCa.

CONCLUSION

Statin use might be associated with reduced PCa risk only when used for a relatively longer duration, and the risk reduction was higher for PCa of higher Gleason score.

The balance between induction and inhibition of mevalonate pathway regulates cancer suppression by statins: A review of molecular mechanisms

Statins are widely used drugs for their role in decreasing cholesterol in hypercholesterolemic patients. Statins through inhibition of Hydroxy Methyl Glutaryl-CoA Reductase (HMGCR), the main enzyme of the cholesterol biosynthesis pathway, inhibit mevalonate pathway that provides isoprenoids for prenylation of different proteins such as Ras superfamily which has an essential role in cancer developing. Inhibition of the mevalonate/isoprenoid pathway is the cause of the cholesterol independent effects of statins or pleotropic effects. Depending on their penetrance into the extra-hepatic cells, statins have different effects on mevalonate/isoprenoid pathway. Lipophilic statins diffuse into all cells and hydrophilic ones use a variety of membrane transporters to gain access to cells other than hepatocytes. It has been suggested that the lower accessibility of statins for extra-hepatic tissues may result in the compensatory induction of mevalonate/isoprenoid pathway and so cancer developing. However, most of the population-based studies have demonstrated that statins have no effect on cancer developing, even decrease the risk of different types of cancer. In this review we focus on the cancer developing "potentials" and the anti-cancer "activities" of statins regarding the effects of statins on mevalonate/isoprenoid pathway in the liver and extra-hepatic tissues.

Synergistic chemopreventive effects of nobiletin and atorvastatin on colon carcinogenesis

Different cancer chemopreventive agents may act synergistically and their combination may produce enhanced protective effects against carcinogenesis than each individual agent alone. Herein, we investigated the chemopreventive effects of nobiletin (NBT, a citrus polymethoxyflavone) and atorvastatin (ATST, a lipid-lowering drug) in colon cancer cells/macrophages and an azoxymethane (AOM)-induced colon carcinogenesis rat model. The results demonstrated that co-treatments of NBT/ATST produced enhanced growth inhibitory and anti-inflammatory effects on the colon cancer cells and macrophages, respectively. Isobologram analysis confirmed that these interactions between NBT and ATST were synergistic. NBT/ATST co-treatment also synergistically induced extensive cell cycle arrest and apoptosis in colon cancer cells. Oral administration of NBT (0.1%, w/w in diet) or ATST (0.04%, w/w in diet) significantly decreased colonic tumor incidence and multiplicity in AOM-treated rats. Most importantly, co-treatment of NBT/ATST at their half doses (0.05% NBT + 0.02% ATST, w/w in diet) resulted in even stronger inhibitory effects on colonic tumor incidence and multiplicity than did NBT or ATST alone at higher doses. Statistical analysis confirmed that the enhanced chemopreventive activities against colon carcinogenesis in rats by the NBT/ATST combination were highly synergistic. Our results further demonstrated that NBT/ATST co-treatment profoundly modulated key cellular signaling regulators associated with inflammation, cell proliferation, cell cycle progression, apoptosis, angiogenesis and metastasis in the colon of AOM-treated rats. In conclusion, for the first time, our results demonstrated a strong synergy in inhibiting colon carcinogenesis produced by the co-treatment of NBT and ATST, which provided a scientific basis for using NBT in combination with ATST for colon cancer chemoprevention in humans.

Preventing aggressive prostate cancer with proven cardiovascular disease preventive methods

Cardiovascular disease (CVD) has been the number one cause of death in the U.S. for 114 of the last 115 years. Risk factors for prostate cancer have primarily mirrored risk proven risk factors for CVD, especially aggressive disease. Obesity, dyslipidemia, glucose intolerance, metabolic syndrome, unhealthy dietary habits or caloric excess, lack of physical activity, and inflammation are just some of these shared risk factors. The evidence also suggests proven CVD preventive measures are identical to prostate cancer preventive measures, especially in regard to aggressive disease. Thus, apart from lifestyle measures that can encourage optimal heart and prostate health there are potentially several dietary supplements that need to be avoided in healthy men because they may also increase the risk of prostate cancer. However, there are also several low-cost, generic, safe in the appropriate individuals, and naturally derived agents that could reduce prostate cancer risk, and these can be discussed and remembered utilizing the acronym S.A.M. (statins, aspirin, and/or metformin).

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.

Statin Use and Prostate Cancer Survival in the Finnish Randomized Study of Screening for Prostate Cancer

BACKGROUND

Recent research has suggested that statins have an effect on prostate cancer prognosis. It is currently unclear how prostate cancer screening, tumor and patient characteristics, or treatment selection may affect this association.

OBJECTIVE

To evaluate the risk of prostate cancer death among statin users. To determine how disease and treatment characteristics affect the association.

DESIGN, SETTING, AND PARTICIPANTS

This is a population-based cohort study consisting of a general male population of Finland participating in the Finnish Randomized Study for Prostate Cancer Screening. The cohort of consisted of 6537 prostate cancer cases diagnosed in the Finnish Randomized Study of Screening for Prostate Cancer population during 1996-2012. The cohort was linked to the National Prescription Database for information on the use of statins and other drugs.

INTERVENTION

Statin use before and after prostate cancer diagnosis compared with nonuse.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Hazard ratios (HRs) for the risk of prostate cancer death by amount, duration, and intensity of statin use. Cox proportional hazards regression with postdiagnostic statin use as a time-dependent variable.

RESULTS

During the median follow-up of 7.5 yr postdiagnosis 617 men died of prostate cancer. Statin use after diagnosis was associated with a decreased risk of prostate cancer death (HR 0.80; 95% confidence interval 0.65-0.98). A decreasing risk trend was observed by increasing intensity of usage (doses/year). The risk decrease was clearest in men managed with androgen deprivation therapy. Prediagnostic statin use was not associated with risk of prostate cancer death (HR 0.92; 95% confidence interval 0.75-1.12).

CONCLUSIONS

Decreased risk of prostate cancer death by statin use after diagnosis suggests that statins may delay or prevent prostate cancer progression. The risk decrease was significant only in men managed with androgen deprivation therapy, but statistical power was limited to estimate the association in men managed with surgery or radiotherapy.

PATIENT SUMMARY

Use of statins after prostate cancer diagnosis was associated with a decreased risk of prostate cancer death. The risk decrease was dose-dependent and observed especially among patients treated with hormone therapy.

Heart healthy equals prostate healthy and statins, aspirin, and/or metformin (S.A.M.) are the ideal recommendations for prostate cancer prevention

Cardiovascular disease (CVD) has been the number one cause of death in the U.S. for 114 of the last 115 years. Lifestyle factors that promote CVD also appear to increase prostate cancer risk and those that reduce CVD risk also appear to reduce the risk of prostate cancer. The largest randomized trials utilizing dietary supplements or pharmacologic agents for prostate cancer prevention (Selenium and Vitamin E Cancer Prevention Trial [SELECT]) have also shed light on the problems and future solutions in this area. Dietary supplements that have not been found to be CVD protective, such as selenium and Vitamin E have not been found to be prostate protective. In addition, over exposure to specific anti-oxidants in nutritionally replete populations may be encouraging cancer growth. Future trials of dietary supplements to prevent prostate cancer could be problematic because by the time a definitive trial is initiated the participants will no longer be “deficient” in the nutrient being tested, which arguably occurred in the SELECT trial. It is also interesting that statins, aspirin, and/or metformin (S.A.M.) are 3 generic, low-cost, heart healthy agents derived from natural sources with separate mechanism of actions, which all appear to have the best benefit to risk ratio compared to any other agent available for prostate cancer prevention, especially aggressive disease, or as an ancillary agent (s) to conventional cancer treatment. It is time to focus on the forest over the trees and recommend proven CVD protective measures for men concerned about their risk of prostate cancer.

Statin use and risk of disease recurrence and death after radical prostatectomy

BACKGROUND

Statins have been linked with improved prostate cancer survival and lower risk of recurrence in men treated with radiation therapy. However, the association is unclear for surgically-treated men. We studied the risk of prostate cancer recurrence and death by statin usage after radical prostatectomy in a cohort of prostate cancer patients treated with radical prostatectomy.

METHODS

A cohort of 1,314 men who underwent curative-intent radical prostatectomy at the Tampere University Hospital, Tampere, Finland during 1995-2009 were linked to national prescription database to obtain detailed information on statin purchases. The risk of PSA recurrence and death (overall and prostate cancer-specific) by statin use before and after the surgery were evaluated using Cox regression with model adjustment for tumor characteristics, total cholesterol and simultaneous use of antidiabetic and antihypertensive drugs. Tissue expression of putative prognostic markers were measured from a subgroup of 323 men.

RESULTS

During the median follow-up of 8.6 years after surgery 484 men recurred, while 244 men died (32 due to prostate cancer). In general statin use before or after prostatectomy was not associated with risk of disease recurrence or death. Tissue expression of Ki-67 and ERG modified the association between statin use and risk of disease recurrence; the risk estimates were lower in men with Ki-67 expression above the median (P for interaction 0.001 and 0.004 for statin use before and after prostatectomy, respectively) and no ERG expression in the tumor tissue (P for interaction 0.006 and 0.011).

CONCLUSIONS

Statin use generally did not affect prostate cancer prognosis after prostatectomy. The effect on disease recurrence may depend on tumor properties, such as proliferation activity. Thus possible future prospective studies should recognize and enroll subgroups of prostate cancer patients most likely to benefit from statins.

Targeting geranylgeranylation reduces adrenal gland tumor burden in a murine model of prostate cancer metastasis

The isoprenoid biosynthetic pathway (IBP) is critical for providing substrates for the post-translational modification of proteins key in regulating malignant cell properties, including proliferation, invasion, and migration. Inhibitors of the IBP, including statins and nitrogenous bisphosphonates, are used clinically for the treatment of hypercholesterolemia and bone disease respectively. The statins work predominantly in the liver, while the nitrogenous bisphosphonates are highly sequestered to bone. Inhibition of the entire IBP is limited by organ specificity and side effects resulting from depletion of all isoprenoids. We have developed a novel compound, disodium [(6Z,11E,15E)-9-[bis(sodiooxy)phosphoryl]-17-hydroxy-2,6,12,16-tetramethyheptadeca-2,6,11,15-tetraen-9-yl]phosphonate (GGOHBP), which selectively targets geranylgeranyl diphosphate synthase, reducing post-translational protein geranylgeranylation. Intracardiac injection of luciferase-expressing human-derived 22Rv1 PCa cells into SCID mice resulted in tumor development in bone (100 %), adrenal glands (72 %), mesentery (22 %), liver (17 %), and the thoracic cavity (6 %). Three weeks after tumor inoculation, daily subcutaneous (SQ) injections of 1.5 mg/kg GGOHBP or the vehicle were given for one month. Dissected tumors revealed a reduction in adrenal gland tumors corresponding to a 54 % (P < 0.005) reduction in total adrenal gland tumor weight of the treated mice as compared to vehicle-treated controls. Western blot analysis of the harvested tissues showed a reduction in Rap1A geranylgeranylation in adrenal glands and mesenteric tumors of the treated mice while non-tumorous tissues and control mice showed no Rap1A alteration. Our findings detail a novel bisphosphonate compound capable of preferentially altering the IBP in tumor-burdened adrenal glands of a murine model of PCa metastasis.

Simultaneous treatment with statins and aspirin reduces the risk of prostate cancer detection and tumorigenic properties in prostate cancer cell lines

Nowadays prostate cancer is the most common solid tumor in men from industrialized countries and the second leading cause of death. At the ages when PCa is usually diagnosed, mortality related to cardiovascular morbidity is high; therefore, men at risk for PCa frequently receive chronic lipid-lowering and antiplatelet treatment. The aim of this study was to analyze how chronic treatment with statins, aspirin, and their combination influenced the risk of PCa detection. The tumorigenic properties of these treatments were evaluated by proliferation, colony formation, invasion, and migration assays using different PCa cell lines, in order to assess how these treatments act at molecular level. The results showed that a combination of statins and aspirin enhances the effect of individual treatments and seems to reduce the risk of PCa detection (OR: 0.616 (95% CI: 0.467-0.812), P<0.001). However, if treatments are maintained, aspirin (OR: 1.835 (95% CI: 1.068-3.155), P=0.028) or the combination of both drugs (OR: 3.059 (95% CI: 1.894-4.939), P<0.001) represents an increased risk of HGPCa. As observed at clinical level, these beneficial effects in vitro are enhanced when both treatments are administered simultaneously, suggesting that chronic, concomitant treatment with statins and aspirin has a protective effect on PCa incidence.

Statin use and incident prostate cancer risk: does the statin brand matter? A population-based cohort study

BACKGROUND

Statins have known anticarcinogenic effects; evidence for long-term statin use as effective chemoprevention for prostate cancer is inconsistent.

METHODS

We conducted a population-based cohort study to examine the association between statin use and risk of prostate cancer using the Database of Clalit Health Services. A total of 66,741 eligible participants were identified at 1 January 2001 and followed through to 31 December 2009. Cox proportional hazard models were used to compute hazard ratios (HRs) of incident prostate cancer associated with statin therapy controling for patients' clinical and sociodemographic characteristics.

RESULTS

A total of 1813 cases of prostate cancer were diagnosed. Statin use was associated with a decreased incidence of prostate cancer, the association was stronger with increasing total dose, hydrophobic statins use and longer periods of treatment. When comparing statin use of over 6 months, this association was strongest for simvastatin (HR 0.51, 95% confidence interval (CI) 0.47-0.56), atorvostatin (HR 0.48, 95% CI 0.33-0.68) and rosuvastatin (HR 0.22, 95% CI 0.08-0.75).

CONCLUSIONS

Our findings suggest that prolonged statin use is associated with a reduced risk of prostate cancer; however, this was not true for all types of statin.

[Pharmaco and diet based prostate cancer prevention]

In 2010, in France, 8,790 men died from prostate cancer despite a low and decreasing mortality rate. The individual risk/benefit ratio of prostate cancer screening is the focus of controversy and currently not in favor of a systematic screening program. Therefore, only prevention could reduce incidence, side effects of treatment and related mortality. Interestingly, prostate cancer prevention is also a field of controversy mainly about 5-alpha-reductase inhibitors. However, it could be expected that pharmaco- or diet-based prevention will be a huge tool for cancer control, even more for prostate cancer burden. This review comprehensively analyses which molecules or compounds could be used in preventive trials. With regard to pharmaco-prevention, three different kinds of drugs could be identified. First drugs, which aim at mainly or even solely reduce prostate cancer risk such as 5-alpha-reductase inhibitors and selective estrogen receptor modulators. Drugs, which aim at wider preventive impact such as: nonsteroidal anti-inflammatory drugs or difluoromethylornithine. Lastly, drugs for which reducing prostate cancer incidence is merely a side effect such as statins, metformin or histones desacetylase inhibitors. With regard to diet-based prevention, two main approaches could be identified: aliments and nutriments, on one hand, and vitamin and minerals, on the other. Interestingly if compounds reach experimental plausibility, natural foods or even global diet seem to have a higher impact. Lastly, besides assessment of efficacy, effectiveness required the critical step of compliance, which might actually be the weakest link of the prevention chain.

Association between statin usage and prostate cancer prevention: a refined meta-analysis based on literature from the years 2005-2010

INTRODUCTION

Statins are cholesterol-lowering drugs that are widely used to prevent and treat atherosclerotic cardiovascular disease. It was found that statins can be associated with the occurrence of prostate cancer. However, no consensus has been concluded.

MATERIALS AND METHODS

In the present study, we provide a refined meta-analysis on the association between statins and prostate cancers. Our objective is to offer a congruent recognition of the impact of statins on prostate cancer.

RESULTS

Our refined analysis has included seven previous publications from the years 2005 to 2010.

CONCLUSIONS

Based on the results, we concluded that there were associations for statin usage in preventing prostate cancer (OR 1.195, 95% CI 1.018-1.403, p = 0.029). Different from previous meta-analyses, our positive conclusion is primarily based on the recent new published literature, which supported the efficiency of statin use to control prostate cancer. More specific efforts for excluding the influence of other factors are crucial in further assessment of the efficiency of statin use.

Activation of AMPK by pterostilbene suppresses lipogenesis and cell-cycle progression in p53 positive and negative human prostate cancer cells

Prostate cancer is one of the leading causes of cancer death in men in Western countries. Epidemiological studies have linked the consumption of fruits and vegetables to a reduced risk of prostate cancer, and small fruits are particularly rich sources of many active phytochemical stilbenes, such as pterostilbene. As a constituent of small fruits such as grapes, berries, and their products, pterostilbene is under intense investigation as a cancer chemopreventive agent. Using the p53 wild type LNCaP and p53 null PC3 cells, we found that treatment with pterostilbene resulted in dose-dependent inhibition of cellular proliferation, which suggested that the interaction of pterostilbene with the p53 might not fully explain its inhibitory effect on proliferation. In this study, we found that pterostilbene activated AMPK in both p53 positive and negative human prostate cancer cells. Pterostilbene-activated AMPK decreased the activity and/or expression of lipogenic enzymes, such as fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC). Interestingly, the resolution between apoptosis and growth arrest following AMPK activation is greatly influenced by p53 status. In p53 positive LNCaP cells, pterostilbene blocked the progression of cell cycle at G1 phase by inducing p53 expression and further up-regulating p21 expression. However, pterostilbene induced apoptosis in p53 negative PC3 cells. Our results suggest that pterostilbene may be a functional chemopreventive agent and that dietary exposure to pterostilbene would be helpful for antiprostate cancer activity.

The importance of LDL and cholesterol metabolism for prostate epithelial cell growth

Cholesterol-lowering treatment has been suggested to delay progression of prostate cancer by decreasing serum LDL. We studied in vitro the effect of extracellular LDL-cholesterol on the number of prostate epithelial cells and on the expression of key regulators of cholesterol metabolism. Two normal prostatic epithelial cell lines (P96E, P97E), two in vitro immortalized epithelial cell lines (PWR-1E, RWPE-1) and two cancer cell lines (LNCaP and VCaP) were grown in cholesterol-deficient conditions. Cells were treated with 1-50 µg/ml LDL-cholesterol and/or 100 nM simvastatin for seven days. Cell number relative to control was measured with crystal violet staining. Changes in mRNA and protein expression of key effectors in cholesterol metabolism (HMGCR, LDLR, SREBP2 and ABCA1) were measured with RT-PCR and immunoblotting, respectively. LDL increased the relative cell number of prostate cancer cell lines, but reduced the number of normal epithelial cells at high concentrations. Treatment with cholesterol-lowering simvastatin induced up to 90% reduction in relative cell number of normal cell lines but a 15-20% reduction in relative number of cancer cells, an effect accompanied by sharp upregulation of HMGCR and LDLR. These effects were prevented by LDL. Compared to the normal cells, prostate cancer cells showed high expression of cholesterol-producing HMGCR but failed to express the major cholesterol exporter ABCA1. LDL increased relative cell number of cancer cell lines, and these cells were less vulnerable than normal cells to cholesterol-lowering simvastatin treatment. Our study supports the importance of LDL for prostate cancer cells, and suggests that cholesterol metabolism in prostate cancer has been reprogrammed to increased production in order to support rapid cell growth.

The optimal male health diet and dietary supplement program

The primary cause of mortality in most developed countries is cardiovascular disease, which is the primary cause of death in the largest clinical studies of male health conditions. There are simplistic correlations between heart health and male-specific diseases. Clinicians need to motivate and provide a simplistic and realistic set of lifestyle, dietary supplement, and prescription drug recommendations to men to affect all-cause morbidity and mortality. This article provides recommendations to assist the clinician and patient to make practical changes that may be accomplished in a short period of time, and should provide tangible overall benefit for men's health.

Statin use and fatal prostate cancer: a matched case-control study

BACKGROUND

Statins are some of the most commonly prescribed medications in medical practice, and prostate cancer is the most common malignancy among men. Although there has been no consistent evidence that statins affect cancer incidence, including prostate cancer, several reports suggest they may decrease the rate of advanced prostate cancer. However, no study to date has specifically examined statin use and prostate cancer mortality. The authors conducted this population-based case-control investigation to examine this association.

METHODS

This was a matched case-control study. Cases were residents of New Jersey ages 55 to 79 years who died from prostate cancer between 1997 and 2000. The cases were matched individually to population-based controls by 5-year age group and race. Medication data were obtained identically for cases and controls from blinded medical chart review. Conditional logistic regression was used to adjust for confounders.

RESULTS

In total, 718 cases were identified, and cooperation was obtained from 77% of their spouses (N = 553). After a review of medical records, 387 men were eligible, and 380 were matched to a control. The unadjusted odds ratio was 0.49 (95% confidence interval, 0.34-0.70) and decreased to 0.37 (P < .0001) after adjusting for education, waist size, body mass index, comorbidities, and antihypertensive medication. There was little difference between lipophilic and hydrophilic statins, but more risk reduction was noted for high-potency statins (73%; P < .0001) compared with low-potency statins (31%; P = .32).

CONCLUSIONS

Statin use was associated with substantial protection against prostate cancer death, adding to the epidemiologic evidence for an inhibitory effect on prostate cancer.

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.

Statin Clinical Trial (REALITY) for prostate cancer: an over 15-year wait is finally over thanks to a dietary supplement

Support for a prescription statin clinical trial for the prevention or treatment of prostate cancer has been lacking, although recent data have provoked interest in such a study. The authors have initiated a pilot trial of red yeast rice (RYR) extract and prostate cancer. RYR significantly reduces low-density lipoprotein and is an option for statin-intolerant patients. RYR appears to be an adequate proxy for some statins as long as quality control is monitored. The REALITY (REduction in Active surveillance Lipid Indices Through Yeast of red rice) trial will be conducted in Toronto, Canada.

The impact of hypertriglyceridemia on prostate cancer development in patients aged ≥60 years

OBJECTIVE

•  To investigate the relationship between serum triglyceride (TG) levels and the incidence and characteristics of prostate cancer detected on biopsy.

PATIENTS AND METHODS

•  We evaluated data from consecutive patients who underwent prostatic biopsy. Data analysed included age, total serum prostate-specific antigen (PSA) level, prostatic volume, body mass index (BMI), TG levels, and cholesterol-lowering medications.

RESULTS

•  We analysed data from 905 patients, including 528 (58.3%) with positive biopsy findings. •  Using 150 mg/dL as the threshold point of TG levels, multivariate analysis yielded an adjusted odds ratio (OR) reflecting the association of higher TG levels with prostate cancer diagnosis of 1.66 (95% confidence interval (CI) 1.21-2.29, P = 0.002). •  Pearson correlation coefficient analysis including age, PSA level, prostatic volume, BMI and TG, showed TG level significantly correlated with BMI (r = 0.185, P < 0.001). •  In the analysis by age intervals (≤59, 60-69, and ≥70 years), the association between high TG levels and positive biopsy findings was enhanced in the age groups 60-69 and ≥70 years (OR 2.10, 95% CI 1.31-3.37, P = 0.002 and OR 1.91, 95% CI 1.03-3.53, P = 0.039, respectively), but not in the group aged ≤59 years. •  In patients aged ≥60 years, high TG levels were statistically significantly associated with a Gleason score of ≥8.

CONCLUSIONS

•  High TG levels correlated well with a higher incidence of prostate cancer, especially in patients aged ≥60 years. •  High TG levels were also associated with a Gleason score of ≥8 in this age group. •  Our results suggest that elderly patients with high TG levels may be more vulnerable to the development of prostate cancer with an aggressive biology.

Statin use is associated with improved prostate cancer survival: is it time for a clinical trial?

Recent studies have reported an inverse association between statin use and risk of advanced prostate cancer. Thus, it is possible that statin exposure delays progression of prostate tumors to an advanced stage. The study by Gutt and colleagues gives two important contributions to this field of research. With a cohort of 691 men undergoing curative-intent radiation therapy for prostate cancer between 1996 and 2008, and with a median follow-up of 50 months, they demonstrate that statin use is associated with improved relapse-free survival. The result supports the idea that statins could delay prostate cancer progression. In addition, they demonstrate that low low-density lipoprotein levels are associated with improved relapse-free survival, supporting the idea that the prostate cancer progression-preventing effects of statins could be, at least in part, mediated by their systemic low-density lipoprotein-lowering effect. The study adds to the growing body of evidence on statins' benefits against prostate cancer. The results have important implications when designing possible future clinical studies on this topic.

mTORC2 is required for proliferation and survival of TSC2-null cells

Mutational inactivation of the tumor suppressor tuberous sclerosis complex 2 (TSC2) constitutively activates mTORC1, increases cell proliferation, and induces the pathological manifestations observed in tuberous sclerosis (TS) and in pulmonary lymphangioleiomyomatosis (LAM). While the role of mTORC1 in TSC2-dependent growth has been extensively characterized, little is known about the role of mTORC2. Our data demonstrate that mTORC2 modulates TSC2-null cell proliferation and survival through RhoA GTPase and Bcl2 proteins. TSC2-null cell proliferation was inhibited not only by reexpression of TSC2 or small interfering RNA (siRNA)-induced downregulation of Rheb, mTOR, or raptor, but also by siRNA for rictor. Increased RhoA GTPase activity and P-Ser473 Akt were inhibited by siRNA for rictor. Importantly, constitutively active V14RhoA reversed growth inhibition induced by siRNA for rictor, siRNA TSC1, reexpression of TSC2, or simvastatin. While siRNA for RhoA had a modest effect on growth inhibition, downregulation of RhoA markedly increased TSC2-null cell apoptosis. Inhibition of RhoA activity downregulated antiapoptotic Bcl2 and upregulated proapoptotic Bim, Bok, and Puma. In vitro and in vivo, simvastatin alone or in combination with rapamycin inhibited cell growth and induced TSC2-null cell apoptosis, abrogated TSC2-null tumor growth, improved animal survival, and prevented tumor recurrence by inhibiting cell growth and promoting apoptosis. Our data demonstrate that mTORC2-dependent activation of RhoA is required for TSC2-null cell growth and survival and suggest that targeting both mTORC2 and mTORC1 by a combination of proapoptotic simvastatin and cytostatic rapamycin shows promise for combinational therapeutic intervention in diseases with TSC2 dysfunction.

Finasteride metabolism and pharmacogenetics: new approaches to personalized prevention of prostate cancer

Incidences of prostate cancer in most countries are increasing owing to better detection methods; however, prevention with the use of finasteride, a very effective steroid 5α-reductase type II inhibitor, has been met with mixed success. A wide interindividual variation in response exists and is thought to be due to heritable factors. This article summarizes the literature that attempts to elucidate the molecular mechanisms of finasteride in terms of its metabolism, excretion and interaction with endogenous steroid molecules. We describe previously reported genetic variations of steroid-metabolizing genes and their potential association with finasteride efficacy. Based on the literature, we outline directions of research that may contribute to understanding the interindividual variation in finasteride prevention and to the future development of personalized medicine.

Statins and prostate cancer: molecular and clinical aspects

The field of the potential applications of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) beyond their unambiguous cardiovascular beneficial effects is steadily increasing. In this regard, statins have also been shown to possess anti-inflammatory, immunomodulatory, antioxidant and growth inhibitory properties. Regarding their role in carcinogenesis, both preclinical and clinical studies report conflicting results. Intriguingly, accumulating evidence suggests that statins may relate to decreased prostate cancer incidence and recurrence risk. However, data from clinical studies seem to be still weak and are confounded by several factors. Nonetheless, preclinical data suggest that statins might exert a chemopreventive role against prostate cancer by inhibiting the proliferation and inducing apoptosis of prostate cancer cells and also inhibiting angiogenesis, inflammation and metastasis. Cholesterol lowering as well as statin pleiotropy through inhibition of the synthesis of isoprenoids have both been implicated in their anticancer properties. In this review, we discuss the preclinical and clinical evidence supporting the preventive or potentially harmful effects of statins on prostate tumourigenesis and conclude that statins should not be recommended for the prevention of prostate cancer development or progression based on the current data.

Liver X receptors, lipids and their reproductive secrets in the male

Liver X receptor (LXR) α and LXRβ belong to the nuclear receptor superfamily. For many years, they have been called orphan receptors, as no natural ligand was identified. In the last decade, the LXR natural ligands have been shown to be oxysterols, molecules derived from cholesterol. While these nuclear receptors have been abundantly studied for their roles in the regulation of lipid metabolism, it appears that they also present crucial activities in reproductive organs such as testis and epididymis, as well as prostate. Phenotypic analyses of mice lacking LXRs (lxr-/-) pointed out their physiological activities in the various cells and organs regulating reproductive functions. This review summarizes the impact of LXR-deficiency in male reproduction, highlighting the novel information coming from the phenotypic analyses of lxrα-/-, lxrβ-/- and lxrα;β-/- mice. This article is part of a Special Issue entitled: Translating nuclear receptor from health to disease.

Metabolic alterations and targeted therapies in prostate cancer

Cancer cells synthesize de novo large amounts of fatty acids and cholesterol, irrespective of the circulating lipid levels and benefit from this increased lipid synthesis in terms of growth advantage, self-survival and drug resistance. Key lipogenic alterations that commonly occur in prostate cancer include over-expression of the enzyme fatty acid synthase (FASN) and deregulation of the 5-AMP-activated protein kinase (AMPK). FASN is a key metabolic enzyme that catalyses the synthesis of palmitate from the condensation of malonyl-CoA and acetyl-CoA de novo and plays a central role in energy homeostasis, by converting excess carbon intake into fatty acids for storage. AMPK functions as a central metabolic switch that governs glucose and lipid metabolism. Recent interest has focused on the potential of targeting metabolic pathways that may be altered during prostate tumorigenesis and progression. Several small molecule inhibitors of FASN have now been described or in development for therapeutic use; in addition, drugs that directly or indirectly induce AMPK activation have potential benefit in prostate cancer prevention and treatment.

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.

Statin and NSAID use and prostate cancer risk

PURPOSE

Some studies have reported reduced risks of advanced, but not early, prostate cancer among statin users, and one study found a reduced risk only among statin users who had also used non-steroidal anti-inflammatory drugs (NSAIDs). We have previously reported no association between statin use and prostate cancer in our hospital-based Case Control Surveillance Study. The purpose of the present analyses was to update the findings by cancer stage and to evaluate the joint use of statins and NSAIDs.

METHODS

Cases were 1367 men with prostate cancer and controls were 2007 men with diagnoses unrelated to statin or NSAID use. We used multivariable logistic regression analyses to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for statin use compared with no use, and joint use of statin and NSAIDs compared with use of neither.

RESULTS

The odds ratio among regular statin users was 1.1 (95%CI 0.9-1.5), and odds ratios were similar among early and late stage cancers. The odds ratio among joint statin and NSAID users was 1.1 (95%CI 0.7-1.6).

CONCLUSION

The present results do not support a protective effect of statin use, or statin and NSAID use, on the risk of advanced prostate cancer.

Prostate cancer and PSA among statin users in the Finnish prostate cancer screening trial

Decreased risk of advanced prostate cancer has been reported among men using statins. However, the evidence on overall prostate cancer risk is conflicting. We compared the relative risk between current users and non-users of statins or other cholesterol-lowering medications in a population undergoing systematical prostate cancer screening. The study cohort comprised of 23,320 men participating in the screening arm of the Finnish prostate cancer screening trial during 1996-2004. Information on medication use was obtained from a comprehensive national prescription database. Cox proportional hazards regression was used to calculate multivariable adjusted hazard ratios (HRs) for prostate cancer. Serum prostate-specific antigen (PSA) level was compared between current users and non-users of cholesterol-lowering drugs. Compared with medication non-users, the overall prostate cancer incidence was decreased among statin users [HR 0.75, 95% confidence interval (CI) 0.63-0.89]. The inverse association was dose-dependent with cumulative amount of statin use, and strongest for low-grade and early stage tumors. The incidence was nonsignificantly lower also among users of other types of cholesterol-lowering drugs (HR 0.62, 95% CI 0.28-1.38), but without dose-dependence. Age-adjusted median serum PSA tended to be lower among users of cholesterol-lowering drugs, but the relative risk decrease among statin users was not related to decreased PSA. Overall incidence of prostate cancer was lowered among statin users when bias due to differential PSA testing between medication users and non-users was eliminated by systematical prostate cancer screening. Cholesterol-lowering with statins seems beneficial for prostate cancer prevention.

Prostate cancer prevention: concepts and clinical recommendations

Prevention is an important strategy for limiting prostate cancer morbidity and mortality. Two major types of prevention are primary (reduction of incident cases) and tertiary (inhibition of disease progression and recurrence). Pharmacological and dietary interventions have potential functions in both the primary and tertiary prevention of prostate cancer. Five-α reductase inhibitors (5-ARIs) reduce the incidence of prostate cancer in both general and higher-risk populations and are currently under study for tertiary prevention in active surveillance and biochemical recurrence patients. Selenium, vitamin E, and vitamin C do not prevent incident prostate cancer in the general population; however, other promising diet-based interventions are currently under study for tertiary prevention. We recommend consideration of 5-ARIs for prostate cancer prevention in (1) asymptomatic men with a PSA ≤ 3.0 ng ml(-1) who are undergoing or anticipate undergoing PSA screening for early detection of prostate cancer and (2) asymptomatic men with PSA ≥ 2.5 and ≤ 10 ng ml(-1) and an earlier prostate biopsy negative for cancer. Men should be informed of the potential risks of 5-ARI therapy. Currently, there is neither clinical evidence to support the use of 5-ARIs for tertiary prevention in active surveillance or biochemical recurrence populations, nor micronutrients for prostate cancer prevention of any type.

Rosuvastatin, identified from a zebrafish chemical genetic screen for antiangiogenic compounds, suppresses the growth of prostate cancer

BACKGROUND

Prostate cancer (PCa) is the most common malignancy in males in Western countries. Despite improvements in standard treatments such as surgery, radiotherapy, and chemotherapy, many patients still progress to advanced stages. Recent clinical trials have shown encouraging results regarding the application of angiogenic inhibitors in the treatment of angiogenesis-dependent diseases, paving the way for novel PCa therapies.

OBJECTIVE

To identify new antiangiogenic compounds and examine their therapeutic potential in models of PCa.

DESIGN, SETTING, AND PARTICIPANTS

We performed a chemical genetic screen in developing zebrafish embryos to identify small molecules inhibiting zebrafish angiogenesis. Transgenic Tg(flk1:EGFP) zebrafish embryos were used in the screening of the Spectrum Collection compound library. Subsequently, the antiangiogenic mechanism of an identified lead compound, rosuvastatin, was studied by conducting endothelial cell function assays and examining antitumor efficacy in a PCa xenograft mouse model. MEASUREMENTS, RESULTS AND LIMITATIONS: Seven lead compounds, including isorotenone, dihydromunduletone, aristolochic acid, simvastatin, mevastatin, lovastatin, and rosuvastatin, were identified to inhibit the growth of the zebrafish intersegmental vessels. Of these seven leads, rosuvastatin was further evaluated for its antiangiogenic mechanism and anticancer efficacy. Rosuvastatin decreased the viability of the human umbilical endothelial cells (HUVECs) (one-half inhibitory concentration: 5.87 microM) by inducing G(1) phase arrest and promoting apoptosis. Moreover, rosuvastatin remarkably inhibited the migration of HUVECs and dose-dependently inhibited the HUVEC capillary-like tube formation in vitro. Furthermore, we demonstrated that rosuvastatin suppressed xenografted PPC-1 prostate tumors in nonobese diabetic severe combined immunodeficiency (NOD-SCID) mice associated with decreased microvessel density (MVD) and tumor cell apoptosis.

CONCLUSIONS

Collectively, our data suggest that rosuvastatin possesses antiangiogenic and antitumor activities and has therapeutic potential for the treatment of PCa. This study represents the first zebrafish antiangiogenic chemical genetic screen to identify a lead compound that targets cancer angiogenesis.

New strategies in prostate cancer: targeting lipogenic pathways and the energy sensor AMPK

Although the role of metabolic syndrome (MS) and a high fat diet in prostate cancer (PCa) risk is still a matter of intense debate, it is becoming increasingly clear that obesity can cause perturbations in metabolic pathways that contribute to the pathogenesis and progression of PCa. Moreover, prostate epithelial cells per se undergo a series of metabolic changes, including an increase in de novo lipogenesis, during the process of tumor formation. These metabolic alterations, at both the cellular and organismal levels, are intertwined with genetic aberrations necessary for neoplastic transformation. Thus, altered metabolism is currently subject to intense research efforts and might provide preventative and therapeutic opportunities, as well as a platform for biomarker development. In this article, we review evidence that the metabolic sensor 5'-AMP-activated protein kinase (AMPK), which physiologically integrates nutritional and hormonal signals and regulates cell survival and growth-related metabolic pathways to preserve intracellular ATP levels, represents a link between energy homeostasis and cancer. Thus, when AMPK is not activated, as in the setting of MS and obesity, systemic metabolic alterations permissive to the development of PCa are allowed to proceed unchecked. Hence, the use of AMPK activators and inhibitors of key lipogenic enzymes may represent a promising therapeutic strategy for PCa.

Liver X Receptor activation downregulates AKT survival signaling in lipid rafts and induces apoptosis of prostate cancer cells

Cholesterol is a structural component of lipid rafts within the plasma membrane. These domains, used as platforms for various signaling molecules, regulate cellular processes including cell survival. Cholesterol contents are tightly correlated with the structure and function of lipid rafts. Liver X receptors (LXRs) have a central role in the regulation of cholesterol homeostasis within the cell. Therefore, we investigated whether these nuclear receptors could modulate lipid raft signaling and consequently alter prostate cancer (PCa) cell survival. Treatment with the synthetic LXR agonist T0901317 downregulated the AKT survival pathway and thus induced apoptosis of LNCaP PCa cells in both xenografted nude mice and cell culture. The decrease in tumor cholesterol content resulted from the upregulation of ABCG1 and the subsequent increase in reverse cholesterol transport. RNA interference experiments showed that these effects were mediated by LXRs. Atomic force microscopy scanning of the inner plasma membrane sheet showed smaller and thinner lipid rafts after LXR stimulation, associated with the downregulation of AKT phosphorylation in these lipid rafts. Replenishment of cell membranes with exogenous cholesterol antagonized these effects, showing that cholesterol is a key modulator in this process. Altogether, pharmacological modulation of LXR activity could thus reduce prostate tumor growth by enhancing apoptosis in a lipid raft-dependent manner.

A chemical biology screen reveals a role for Rab21-mediated control of actomyosin contractility in fibroblast-driven cancer invasion

Background:

Carcinoma-associated fibroblasts (CAFs) can promote the progression of tumours in many ways. They can remodel the extracellular matrix to generate an environment that enables the invasion of cancer cells. We hypothesised that compounds that prevent matrix remodelling by CAFs would block their ability to promote carcinoma cell invasion.

Methods:

We designed a screen for compounds that interfere with CAF-promoted matrix remodelling. Hits from this screen were investigated in organotypic invasion models of squamous cell carcinoma (SCC).

Results:

We find that lovastatin and simvastatin reduce matrix remodelling by fibroblasts and thereby reduce SCC invasion. This class of compounds exert their effects partly through disrupting the function of Rab proteins, and we show a new role for Rab21 in promoting cancer cell invasion promoted by CAFs.

Conclusions:

Rab21 is required for CAFs to promote the invasion of cancer cells. It enables the accumulation of integrin α5 at the plasma membrane and subsequent force-mediated matrix remodelling.

The effects of lovastatin on conventional medical treatment of lower urinary tract symptoms with finasteride

OBJECTIVE

To explore whether or not statins have any impact on the progression of components of benign prostatic hyperplasia (lower urinary tract symptoms severity, prostate volume and serum prostate specific antigen (PSA) when combined with other agents inhibiting growth of prostate cells.

MATERIALS AND METHODS

This was a preliminary, clinical study. Eligible patients were aged > 50 yrs, with International Prostate Symptom Score (IPSS) between 9 and 19, total prostate volume (TPV) >40 mL, and serum PSA > 1.5 ng/mL. Patients were divided in two groups: those with and those without lipidemia. After selection, eligible BPH patients with lipidemia (n = 18) were prescribed lovastatin 80 mg daily and finasteride 5 mg daily, while eligible patients without lipidemia (n = 15) were prescribed only finasteride 5 mg daily. IPSS, TPV and serum PSA were evaluated at end point (4 months).

RESULTS

There was no difference between the two groups on the primary end point of mean change from baseline in IPSS (p = 0.69), TPV (p = 0.90) and PSA (p = 0.16) after 4 months of treatment.

CONCLUSIONS

Short-term lovastatin treatment does not seem to have any effect on IPSS, TPV and PSA in men with prostatic enlargement due to presumed BPH.

Novel lipogenic enzyme ELOVL7 is involved in prostate cancer growth through saturated long-chain fatty acid metabolism

A number of epidemiologic studies have indicated a strong association between dietary fat intake and prostate cancer development, suggesting that lipid metabolism plays some important roles in prostate carcinogenesis and its progression. In this study, through our genome-wide gene expression analysis of clinical prostate cancer cells, we identified a novel lipogenic gene, ELOVL7, coding a possible long-chain fatty acid elongase, as overexpressed in prostate cancer cells. ELOVL7 expression is regulated by the androgen pathway through SREBP1, as well as other lipogenic enzymes. Knockdown of ELOVL7 resulted in drastic attenuation of prostate cancer cell growth, and it is notable that high-fat diet promoted the growth of in vivo tumors of ELOVL7-expressed prostate cancer. In vitro fatty acid elongation assay and fatty acid composition analysis indicated that ELOVL7 was preferentially involved in fatty acid elongation of saturated very-long-chain fatty acids (SVLFA, C20:0 approximately ). Lipid profiles showed that knockdown of ELOVL7 in prostate cancer cells affected SVLFAs in the phospholipids and the neutral lipids, such as cholesterol ester. Focusing on cholesterol ester as a source of de novo steroid synthesis, we show that ELOVL7 affected de novo androgen synthesis in prostate cancer cells. These findings suggest that EVOLV7 could be involved in prostate cancer growth and survival through the metabolism of SVLFAs and their derivatives, could be a key molecule to elucidate the association between fat dietary intake and prostate carcinogenesis, and could also be a promising molecular target for development of new therapeutic or preventive strategies for prostate cancers.