Inhibition of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase pathway induces p53-independent transcriptional regulation of p21(WAF1/CIP1) in human prostate carcinoma cells

Statins as Secondary Preventive Agent to Limit Breast Cancer Metastatic Outgrowth

Metastasis is a leading cause of mortality in breast cancer, as metastatic disease is often aggressive and resistant to conventional treatments. Cancer cells that spread to distant organs can enter a dormant phase for extended periods, sometimes years or decades. During this dormant phase, cancer cells avoid immune and pharmacological response. Thus, new approaches are needed to prevent these disseminated cells from becoming lethal cancers. Statins are known inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase that have been extensively used in patients with cardiovascular diseases to lower cholesterol. However, recent research has demonstrated their potential in anticancer therapies. Epidemiological evidence suggests that statins are associated with a reduction in breast cancer-specific mortality, although they do not appear to affect the incidence of primary tumors. In this review, we discuss the role of statins in metastasis and dormancy, their cytocidal and cytostatic effects and their interactions with different cell types in the tumor microenvironment. The exact mechanisms by which statins reduce mortality without influencing primary tumor growth remain unclear, also warranting further investigation into their potential role in metastasis and tumor dormancy, which could ultimately help patients to improve survival and quality of life.

Modulation of radiosensitivity of DU145 prostate carcinoma cells by simvastatin

PURPOSE

To investigate antiproliferative effects of simvastatin in combination with ionizing radiation on DU145 prostate cancer cells and its influence on cellular HMG-CoA-reductase levels.

METHODS

Proliferative responses of DU145 cells were estimated by means of a clonogenic assay or the crystal violet procedure. HMG-CoA-reductase levels were measured by western blot analysis.

RESULTS

The antiproliferative effects of simvastatin and radiation are dependent on simvastatin dose, radiation dose and treatment time. In vitro treatment of DU145 cells with simvastatin induced HMG-CoA-reductase levels.

CONCLUSION

Ionizing radiation more profoundly reduces proliferation as compared to simvastatin exposure, while the combined application of both modalities is synergistic. The inhibition of CoA-reductase may contribute to these effects.

Evidence on Statins, Omega-3, and Prostate Cancer: A Narrative Review

Dietary intake selections might play a crucial role in prostate cancer (PCa) occurrence and progression. Several studies have investigated whether statin use could reduce PCa risk but with conflicting results. Nevertheless, a significantly decreased incidence of advanced PCa has been consistently noted. Statins may also reduce the risk of biochemical recurrence (BCR) in men with PCa after receiving active treatment. However, the influence of statin usage on BCR and PCa progression in men with high prostate-specific antigen levels has been found to be insignificant. In contrast, the combined use of a statin and metformin was significantly related to the survival status of PCa patients. However, some studies have revealed that the intake of long-chain omega-3 fatty acid (ω-3) from fish or fish oil supplements may elevate PCa risk. Several meta-analyses on ω-3 consumption and PCa have shown controversial results for the relationship between PCa and ω-3 consumption. However, studies with positive results for various genotypes, fatty acid intake or levels, and PCA risk are emerging. This review highlights the association among statins, ω-3, and PCa. The findings summarized here may be helpful for clinicians counseling patients related to PCa.

A Mathematical Model of In Vitro Cellular Uptake of Zoledronic Acid and Isopentenyl Pyrophosphate Accumulation

The mevalonate pathway is an attractive target for many areas of research, such as autoimmune disorders, atherosclerosis, Alzheimer’s disease and cancer. Indeed, manipulating this pathway results in the alteration of malignant cell growth with promising therapeutic potential. There are several pharmacological options to block the mevalonate pathway in cancer cells, one of which is zoledronic acid (ZA) (an N-bisphosphonate (N-BP)), which inhibits the farnesyl pyrophosphate (FPP) synthase enzyme, inducing cell cycle arrest, apoptosis, inhibition of protein prenylation, and cholesterol reduction, as well as leading to the accumulation of isopentenyl pyrophosphate (IPP). We extrapolated the data based on two independently published papers that provide numerical data on the uptake of zoledronic acid (ZA) and the accumulation of IPP (Ag) and its isomer over time by using in vitro human cell line models. Two different mathematical models for IPP kinetics are proposed. The first model (Model 1) is a simpler ordinary differential equation (ODE) compartmental system composed of 3 equations with 10 parameters; the second model (Model 2) is a differential algebraic equation (DAE) system with 4 differential equations, 1 algebraic equation and 13 parameters incorporating the formation of the ZA+enzyme+Ag complex. Each of the two models aims to describe two different experimental situations (continuous and pulse experiments) with the same ZA kinetics. Both models fit the collected data very well. With Model 1, we obtained a prevision accumulation of IPP after 24 h of 169.6 pmol/mgprot/h with an IPP decreasing rate per (pmol/mgprot) of ZA (kXGZ) equal to 13.24/h. With Model 2, we have comprehensive kinetics of IPP upon ZA treatment. We calculate that the IPP concentration was equal to 141.6 pmol/mgprot/h with a decreasing rate/percentage of 0.051 (kXGU). The present study is the first to quantify the influence of ZA on the pharmacodynamics of IPP. While still incorporating a small number of parameters, Model 2 better represents the complexity of the biological behaviour for calculating the IPP produced in different situations, such as studies on γδ T cell-based immunotherapy. In the future, additional clinical studies are warranted to further evaluate and fine-tune dosing approaches.

Statin Use and the Risk of Prostate Cancer Biochemical Recurrence Following Definitive Therapy: A Systematic Review and Meta-Analysis of Cohort Studies

Background

Numerous studies have reported the role of statins on biochemical recurrence (BCR) among patients with prostate cancer (PCa) after definite treatment. However, the conclusions of these studies are contradictory. We aimed to determine the effect of statins on BCR of PCa using a systematic review and meta-analysis.

Methods

We searched PubMed (Medline) and other databases for cohort studies evaluating the effect of statins on the BCR of patients with PCa between January 1, 2000, and December 31, 2021. The random effects (RE) model and quality effects (QE) model were used to calculate the pooled hazard ratio (pHR) and pooled risk ratio (pRR) and their 95% confidence interval (95% CI).

Results

A total of 33 cohort studies were finally selected and included in this systematic review and meta-analysis. Statin use was significantly associated with a 14% reduction in the HR of BCR (pHR: 0.86, 95% CI: 0.78 to 0.95, I² = 64%, random effects model, 31 studies) and a 26% reduction in the RR of BCR (pRR: 0.74, 95% CI: 0.57 to 0.94, 24,591 patients, I² = 88%, random effects model, 15 studies) among patients with PCa. The subgroup analyses showed that statins could result in 22% reduction in the HR of BCR (pHR: 0.78, 95% CI: 0.61 to 0.98, I² = 57%, random effects model) among patients accepting radiotherapy (RT).

Conclusions

Our study suggests that statins have a unique role in the reduction of BCR in patients with PCa after definite treatment, especially RT. In the future, more clinical trials and in vitro and animal experiments are needed to further verify the effects of statins in PCa and the potential mechanisms.

Cell Cycle Progression and Synchronization: An Overview

The cell cycle is the series of events that take place in a cell that drives it to divide and produce two new daughter cells. Through more than 100 years of efforts by scientists, we now have a much clearer picture of cell cycle progression and its regulation. The typical cell cycle in eukaryotes is composed of the G1, S, G2, and M phases. The M phase is further divided into prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. Cell cycle progression is mediated by cyclin-dependent kinases (Cdks) and their regulatory cyclin subunits. However, the driving force of cell cycle progression is growth factor-initiated signaling pathways that controls the activity of various Cdk-cyclin complexes. Most cellular events, including DNA duplication, gene transcription, protein translation, and post-translational modification of proteins, occur in a cell-cycle-dependent manner. To understand these cellular events and their underlying molecular mechanisms, it is desirable to have a population of cells that are traversing the cell cycle synchronously. This can be achieved through a process called cell synchronization. Many methods have been developed to synchronize cells to the various phases of the cell cycle. These methods could be classified into two groups: synchronization methods using chemical inhibitors and synchronization methods without using chemical inhibitors. All these methods have their own merits and shortcomings.

The role of metformin, statins and diet in men on active surveillance for prostate cancer

PURPOSE OF REVIEW

A sound scientific basis has been emerging on the anti-neoplastic role of metformin, statins and dietary interventions. However, evidence in prostate cancer patients remains mixed owing to an absence of completed randomized trials. This overview examines the rationale for metformin, statins and dietary intervention for secondary prevention in men on active surveillance by summarizing current evidence base and biological mechanisms in influencing cancer progression and mortality.

METHODS

A comprehensive literature search was performed to identify studies that evaluated the role of metformin, statins and diet in the secondary prevention of prostate cancer as well as those that described the anti-cancer mechanisms of these agents. The search included Pubmed, MEDLINE, EMBASE and Cochrane library from inception till August 2021.

RESULTS

A total of 14 trials on metformin, 21 trials on statins and 13 trials on dietary measures were evaluated. Majority were observational population-based cohort studies or meta-analysis of them. Three ongoing prospective randomized controlled trials were also reported. Overall, mixed results were obtained.

CONCLUSIONS

The role of metformin and statins remains promising with several trials showing reduced rates of progression and cancer specific mortality. Combination therapy strategies have also been evaluated in more advanced patients showing synergism. Dietary interventions especially fruits, vegetables and fish intake has shown some benefit albeit with mixed results for others like legumes, red meat, coffee and multivitamins. Several ongoing randomized trials will provide stronger evidence in the future for secondary prevention.

Statins use and cancer: an update

After initial concerns regarding the association of statins with increased incidences of cancer and elevated cancer-related mortality, there are now plenty of data on the antitumor, cytostatic and cytotoxic effectiveness of this class of drugs. Here, we present a short review of possible mechanisms of antineoplastic activity obtained from preclinical research and the influence of statins on cancer treatment. In the second part of the article, we focus on the most recent data from observational clinical trials, as well as meta-analyses regarding cancer incidence and mortality in patients treated with statins.

An analysis of the effect of statins on the risk of Non-Hodgkin's Lymphoma in the Women's Health Initiative cohort

Statins have been shown to induce a phosphoprotein signature that modifies MYC (myelocytomatosis viral oncogene) activation and to have anti‐inflammatory activity that may impact the risk of Non‐Hodgkin's lymphoma (NHL). We analyzed the relationship between statins and risk of NHL using data from the Women's Health Initiative (WHI). The study population included 161,563 postmenopausal women ages 50–79 years from which 712 cases of NHL were diagnosed after 10.8 years of follow‐up. Information on statin use and other risk factors was collected by self‐ and interviewer‐administered questionnaires. Multivariable‐adjusted HR and 95% CI evaluating the relationship between statin use at baseline, as well as in a time‐dependent manner and risk of NHL, were computed from Cox proportional hazards analyses. A separate analysis was performed for individual NHL subtypes: diffuse large B‐Cell lymphoma (DLBCL) (n = 228), follicular lymphoma (n = 169), and small lymphocytic lymphoma (n = 74). All statistical tests were two‐sided. There was no significant association between use of statins at baseline and risk of NHL (HR 0.85, 95% C.I. 0.67–1.08). However, in the multivariable‐adjusted time‐dependent models, statin use was associated with a borderline lower risk of NHL (HR 0.81, 95% C.I. 0.66–1.00). Considering subtypes of NHL, statin use was associated with a lower risk of DLBCL (HR 0.62, 95% C.I. 0.42–0.91). This effect was driven by lipophilic statins (HR 0.62, 95% C.I. 0.40–0.96). In the WHI, statins were associated with a lower overall risk of DLBCL, particularly attributable to lipophilic statins. These results may have impact on primary or secondary prevention of NHL, particularly DLBCL.

An analysis of the association between statin use and risk of endometrial and ovarian cancers in the Women's Health Initiative

BACKGROUND

Statins have anti proliferative activity in vitro against endometrial and ovarian cancer and can affect levels of reproductive hormones. We analyzed data from the Women's Health Initiative (WHI) to assess whether statins are associated with risk of endometrial and ovarian cancer.

METHODS

The WHI study included 161,808 postmenopausal women in which incident cases of endometrial (n = 1377) and ovarian cancer (n = 763) were identified over an average of 10.8 (SD + 3.3) years. Information on statin use and risk factors was collected at baseline and follow-up. Cox proportional hazards regression was used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for the association of statin use and risk of endometrial and ovarian cancer. All statistical tests were two-sided.

RESULTS

Statins were used at baseline by 7.5% women and by up to 25% at year nine. The multivariable adjusted HR for risk of endometrial cancer for baseline statin use was 0.74, 95% C.I. 0.59-0.94 and for ovarian cancer was 1.15, 95% C.I. 0.89-1.50. In time-dependent models, statins were not associated with endometrial cancer (HR 0.91, 95% C.I. 0.76-1.08) however there was an increased risk of ovarian cancer (HR 1.30, 95% CI 1.04-1.62), largely attributed to the effect of the hydrophilic statin, pravastatin (1.89, 95% CI 1.24-2.88).

CONCLUSIONS

There was a reduction in risk of endometrial cancer among statin users at baseline but not in time-dependent models. Pravastatin use was associated with an increased risk of ovarian cancer. Analyses of larger numbers of cases are needed to evaluate these findings.

The current evidence on statin use and prostate cancer prevention: are we there yet?

An increasing amount of data supports an inverse association between statin use and cancer risk. The findings for prostate cancer, particularly advanced disease, are the most promising of all cancers studied. Use of these agents seems to also be associated with improved prostate- cancer-specific survival, particularly in men undergoing radiotherapy, suggesting usefulness of statins in secondary and tertiary prevention. Some study results might be influenced by increased PSA screening and health-conscious behaviour in statin users but these factors are unlikely to completely account for observed beneficial effects. The epidemiological evidence is supported by preclinical studies that show that statins directly inhibit prostate cancer development and progression in cell-based and animal-based models. The antineoplastic effect of statins might arise from a number of cholesterol-mediated and non-cholesterol-mediated mechanisms that affect pathways essential for cancer formation and progression. Understanding these mechanisms is instrumental in drug discovery research for the development of future prostate cancer therapeutics, as well as in designing clinical trials to test a role for statins in prostate cancer prevention. Currently, sufficient data are lacking to support the use of statins for the primary prevention of prostate cancer and further research is clearly warranted. Secondary and tertiary prevention trials in men who have been diagnosed with prostate cancer might soon be performed.

Neurocytoprotective Effects of Aliphatic Hydroxamates from Lovastatin, a Secondary Metabolite from Monascus-Fermented Red Mold Rice, in 6-Hydroxydopamine (6-OHDA)-Treated Nerve Growth Factor (NGF)-Differentiated PC12 Cells

Lovastatin, a secondary metabolite isolated from Monascus-fermented red rice mold, has neuroprotective activity and permeates the blood-brain barrier. The aim of this study was to enhance the activity of lovastatin for potential use as a treatment for neuronal degeneration in Parkinson's disease. Six lovastatin-derived compounds were semisynthesized and screened for neurocytoprotective activity against 6-hydroxydopamine (6-OHDA)-induced toxicity in human neuroblastoma PC12 cells. Four compounds, designated as 3a, 3d, 3e, and 3f, significantly enhanced cell viability. In particular, compound 3f showed excellent neurocytoprotective activity (97.0 ± 2.7%). Annexin V-FITC and propidium iodide double staining and 4',6-diamidino-2-phenylindole staining indicated that compound 3f reduced 6-OHDA-induced apoptosis in PC12 cells. Compound 3f also reduced caspase-3, -8, and -9 activities, and intracellular calcium concentrations elevated by 6-OHDA in a concentration-dependent manner, without inhibiting reactive oxygen species generation. JC-1 staining indicated that compound 3f also stabilized mitochondrial membrane potential. Thus, compound 3f may be used as a neurocytoprotective agent. Future studies should investigate its potential application as a treatment for Parkinson's disease.

Cell-Cycle Gene Expression in Lovastatin-Induced Medulloblastoma Apoptosis

Background:

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase is a key rate-limiting enzyme in the mevalonate pathway, which generates precursors both for cholesterol biosynthesis and for the production of nonsteroidal mevalonate derivatives that are involved in a number of growth-regulatory processes. We have reported that lovastatin, a competitive inhibitor of HMG-CoA reductase, not only inhibits medulloblastoma proliferation in vitro, but also induces near-complete cell death via apoptosis. The mechanism of this phenomenon is unclear. Possible involvement of changes in expression of certain cell-cycle related genes led us to study some of them in more detail.

Methods:

Medulloblastoma cell lines were exposed in vitro to lovastatin, and the effects of gene expression changes were studied using RT-PCR, antisense oligonucleotide, DNA electrophoresis and Western blotting analysis.

Results:

1) Levels of total Ras gene mRNA and individual Ras gene mRNA are stable in lovastatin treatment in all examined medulloblastoma cell lines. 2) Blocking c-myc gene over-expression does not enhance medulloblastoma cell sensitivity to lovastatin. 3) Following lovastatin treatment, p16 expression exhibits no change, but pronounced increases of p27KIP1 protein are observed in all examined cell lines. Lovastatin induces pronounced increases of p21WAF1 protein only in Daoy and UW228, but not in D283 Med and D341 Med. 4) Following lovastatin treatment, increased p53 protein is detected only in D341 Med, and bax protein is unchanged in all cell lines.

Conclusion:

Lovastatin-induced growth inhibition and apoptosis in medulloblastoma are not dependent on the regulation of Ras and c-myc gene expression, but may be mediated by p27KIP1 gene expression. Lovastatin-induced apoptosis in medulloblastoma is probably p53 independent, but p53 and p21WAF1 gene expression may also mediate anti-proliferative effects of lovastatin on specific medulloblastoma cell lines.

HMG-CoA reductase inhibitors as adjuvant treatment for hematologic malignancies: what is the current evidence?

Statins have been shown to possess properties that go beyond their lipid-lowering effects. These agents act on the mevalonate pathway and inhibit synthesis of cholesterol, geranylgeranyl pyrophosphate, and farnesyl pyrophosphate, which are necessary for posttranslational modification of the Rho, Rac, and Ras superfamily of proteins. Early phase studies have demonstrated that this modulation of cellular signaling can ultimately exert pro-apoptotic, anti-angiogenic, and immunomodulatory effects, and might even restore chemosensitivity in several hematologic cancers. Nonetheless, these promising preclinical results have not yet migrated from the bench to the bedside as their effectiveness as adjuvant agents in hematologic malignancies is currently uncertain. In the present review, we summarize the existing evidence stemming from preclinical and clinical studies pertaining to the use of statins as adjuvant therapies in hematologic malignancies, and discuss the new insights gained from the ongoing translational research.

Simvastatin plus capecitabine-cisplatin versus placebo plus capecitabine-cisplatin in patients with previously untreated advanced gastric cancer: a double-blind randomised phase 3 study

PURPOSE

We aimed to the addition of synthetic 3-hydroxy-3-methyglutaryl coenzyme A (HMG-CoA) reductase inhibitor, simvastatin to capecitabine-cisplatin (XP) in patients with previously untreated advanced gastric cancer (AGC).

METHODS

In this double-blind, placebo-controlled, phase III study, we enrolled patients aged 18 years or older with histological or cytological confirmed metastatic adenocarcinoma of the stomach or gastroesophageal junction (GEJ) at nine centres in Korea. Patients, stratified by disease measurability and participating site, were randomly assigned (1:1) to receive capecitabine 1000mg/m(2) twice daily for 14 days and cisplatin 80 mg/m(2) on day 1 every 3 weeks plus either simvastatin 40 mg or placebo, once daily. Cisplatin was given for 8 cycles; capecitabine and simvastatin were administered until disease progression or unacceptable toxicities. This study is registered with ClinicalTrials.gov, number NCT01099085.

RESULTS

Between February 2009 and November 2012, 244 patients were enrolled and assigned to treatment groups (120 simvastatin, 124 placebo). Median progression free survival (PFS) for 120 patients allocated XP plus simvastatin was 5.2 months (95% confidence interval (CI) 4.3-6.1) compared with 4.63 months (95% CI 3.5-5.7) for 124 patients who were allocated to XP plus placebo (hazard ratio 0.930, 95% CI 0.684-1.264; p=0.642). 63 (52.5%) of 120 patients in simvastatin group and 70 (56.4%) of 124 had grade 3 or higher adverse events.

CONCLUSIONS

Addition of 40 mg simvastatin to XP does not increase PFS in our trial, although it does not increase toxicity. Low dose of simvastatin (40 mg) to chemotherapy is not recommended in untargeted population with AGC.

A randomized, double-blind, placebo-controlled phase II clinical trial of lovastatin for various endpoints of melanoma pathobiology

On the basis of large cardiovascular clinical trials of lipid-lowering agents that showed a considerable decrease in the incidence of primary melanomas in the active agent arm, we have carried out a randomized, double-blind clinical trial examining the impact of lovastatin on various biomarkers of melanoma pathogenesis. Subjects with at least two clinically atypical nevi were randomized to receive oral lovastatin or placebo for a 6-month period. Clinical, histopathologic, and molecular biomarkers were evaluated for change in the two groups. Eighty subjects were randomized, evaluable, and included in the analyses. Lovastatin showed no benefit in comparison with placebo in the primary endpoint of decreasing the level of histopathologic atypia, nor in any of the secondary endpoints of decreasing clinical atypia, impact on nevus number, nor in showing significant changes in any of the molecular biomarkers. There were no significant differences in adverse event profiles for lovastatin compared with placebo. The lovastatin arm did show a significant and considerable decrease in total serum cholesterol and serum low-density lipoprotein (LDL) levels compared with placebo, an expected result. This finding bolsters confidence in subject compliance. Given the results of this trial, it is concluded that if lovastatin were to lower the incidence of melanoma, it would appear not to be doing so by reversing atypia of precursor atypical nevi over the 6-month time frame studied. Further research into the pathogenesis of melanoma and in other potential chemopreventive agents is needed.

β-ionone induces cell cycle arrest and apoptosis in human prostate tumor cells

3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase is the rate-limiting activity in the mevalonate pathway that provides essential intermediates for posttranslational modification of growth-associated proteins. Assorted dietary isoprenoids found in plant foods suppress HMG CoA reductase and have cancer chemopreventive activity. β-Ionone, a cyclic sesquiterpene and an end-ring analog of β-carotene, induced concentration-dependent inhibition of the proliferation of human DU145 (IC50 = 210 μmol/L) and LNCaP (IC50 = 130 μmol/L) prostate carcinoma cells and PC-3 prostate adenocarcinoma cells (IC50 = 130 μmol/L). Concomitantly, β-ionone-induced apoptosis and cell cycle arrest at the G1 phase in DU145 and PC-3 cells were shown by fluorescence microscopy, flow cytometry, and TUNEL reaction, and downregulation of cyclin-dependent kinase 4 (Cdk4) and cyclin D1 proteins. Growth suppression was accompanied by β-ionone-induced downregulation of reductase protein. A blend of β-ionone (150 μmol/L) and trans, trans-farnesol (25 μmol/L), an acyclic sesquiterpene that putatively initiates the degradation of reductase, suppressed the net growth of DU145 cells by 73%, an impact exceeding the sum of those of β-ionone (36%) and farnesol (22%), suggesting a synergistic effect. β-ionone, individually or in combination with other HMG CoA reductase suppressors, may have potential in prostate cancer chemoprevention and/or therapy.

Geranylgeraniol suppresses the viability of human DU145 prostate carcinoma cells and the level of HMG CoA reductase

The rate-limiting enzyme of the mevalonate pathway, 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, provides essential intermediates for the prenylation of nuclear lamins and Ras and dolichol-mediated glycosylation of growth factor receptors. The diterpene geranylgeraniol downregulates the level of HMG CoA reductase and suppresses the growth of human liver, lung, ovary, pancreas, colon, stomach, and blood tumors. We evaluated the growth-suppressive activity of geranylgeraniol in human prostate carcinoma cells. Geranylgeraniol induced dose-dependent suppression of the viability of human DU145 prostate carcinoma cells (IC50=80±18 µmol/L, n=5) following 72-h incubations in 96-well plates. Cell cycle was arrested at the G1 phase with a concomitant decrease in cyclin D1 protein. Geranylgeraniol-induced apoptosis was detected by flow cytometric analysis, fluorescence microscopy following acridine orange and ethidium bromide dual staining, and caspase-3 activation. Geranylgeraniol-induced viability suppression was accompanied by concentration-dependent decrease in the level of HMG CoA reductase protein. As a nonsterol molecule that downregulates HMG CoA reductase in the presence of sterols, geranylgeraniol may have potential in the chemoprevention and/or therapy of human prostate cancer.

Simvastatin-induced compartmentalisation of doxorubicin sharpens up nuclear topoisomerase II inhibition in human rhabdomyosarcoma cells

Tumours, which are initially sensitive to cytotoxic agents, often develop resistance to a broad spectrum of structurally unrelated drugs. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been shown to inhibit ATP-binding cassette (ABC) transporters but have also impact on glycosylation of such proteins. Doxorubicin is a substrate for ABC transporters like P-glycoprotein (ABCB1) which is present in human RD rhabdomyosarcoma cells. It was therefore the aim of this study to identify the compartmentalisation and action of doxorubicin in simvastatin-treated RD cells. Due to autofluorescence of doxorubicin, intracellular distribution was monitored by confocal microscopy. The biological effects were traced on the level of colony formation, caspase activation and DNA injury. Here we show that simvastatin treatment leads to ABCB1 inhibition and down-regulation of the transporter. Consequently, these cells accumulate significant amounts of doxorubicin, predominantly in the nucleus and lysosomes. While clearance of the anthracycline into lysosomes is not altered by simvastatin treatment, it significantly enhanced nuclear accumulation in a HMG-CoA reductase-independent manner. Thus, in such treated cells, topoisomerase II activity is significantly inhibited, which is further corroborated by augmented double-strand DNA breaks. Moreover, colony formation was synergistically inhibited by the combination of simvastatin and doxorubicin. Given the fact that ABCB1 expression correlates with an adverse prognosis in many tumours, adjuvant chemotherapy including statins might represent a novel therapeutic concept to overcome ABCB1-mediated multidrug resistance by direct inhibition and down-regulation.

Crocetin induces cytotoxicity in colon cancer cells via p53-independent mechanisms

OBJECTIVE

Crocin has been proposed as a promising candidate for cancer chemoprevention. The purpose of this investigation was to investigate the chemopreventive action and the possible mechanisms of crocin against human colon cancer cells in vitro.

METHODS

Cell proliferation was examined using MTT assay and the cell cycle distribution fractions were analyzed using flow cytometric analysis after propidium iodide staining. Apoptosis was detected using the TUNEL Apoptosis Detection Kit with laser scanning confocal microscope. DNA damage was assessed using the alkaline single-cell gel electrophoresis assay, while expression levels of p53, cdk2, cyclin A and P21 were examined by Western blot analysis.

RESULTS

Treatment of SW480 cells with crocetin (0.2, 0.4, 0.8 mmol/L) for 48 h significantly inhibited their proliferation in a concentration-dependent manner. Crocetin (0.8 mmol/L) significantly induced cell cycle arrest through p53-independent mechanisms accompanied by P21 induction. Crocetin (0.8 mmol/L) caused cytotoxicity in the SW480 cells by enhancing apoptosis and decreasing DNA repair capacity in a time-dependent manner.

CONCLUSIONS

This report provides evidence that crocetin is a potential anticancer agent, which may be used as a chemotherapeutic drug.

Atorvastatin activates heme oxygenase-1 at the stress response elements

Statins are known to inhibit growth of a number of cancer cells, but their mechanism of action is not well established. In this study, human prostate adenocarcinoma PC-3 and breast adenocarcinoma MCF-7 cell lines were used as models to investigate the mechanism of action of atorvastatin, one of the statins. Atorvastatin was found to induce apoptosis in PC-3 cells at a concentration of 1 μM, and in MCF-7 cells at 50 μM. Initial survey of possible pathway using various pathway-specific luciferase reporter assays showed that atorvastatin-activated antioxidant response element (ARE), suggesting oxidative stress pathway may play a role in atorvastatin-induced apoptosis in both cell lines. Among the antioxidant response genes, heme oxygenase-1 (HO-1) was significantly up-regulated by atorvastatin. Pre-incubation of the cells with geranylgeranyl pyrophosphate blocked atorvastatin-induced apoptosis, but not up-regulation of HO-1, suggesting that atorvastatin-induced apoptosis is dependent on GTPase activity and up-regulation of HO-1 gene is not. Six ARE-like elements (designated StRE1 [stress response element] through StRE6) are present in the HO-1 promoter. Atorvastatin was able to activate all of the elements. Because these StRE sites are present in clusters in HO-1 promoter, up-regulation of HO-1 by atorvastatin may involve multiple StRE sites. The role of HO-1 in atorvastatin-induced apoptosis in PC-3 and MCF-7 remains to be studied.

Statins and cancer: current and future prospects

Statins are inhibitors of 3-hydroxy-methylglutaryl (HMG) CoA reductase. They exhibit effects beyond cholesterol reduction, including anticancer activity. This review presents the effects of statins in vitro and their possible molecular anticancer mechanisms and critically discusses the data regarding the role of statins in cancer prevention. Finally, this review focuses on the use of statins combined with other chemotherapeutics to increase the effectiveness of cancer treatments. Despite rare and inconclusive clinical data, the preclinical results strongly suggest that such combined treatment could be a promising new strategy for the treatment of certain tumor types.

The association of statins and taxanes: an efficient combination trigger of cancer cell apoptosis

Background:

Cancer cell killing might be achieved by the combined use of available drugs. Statins are major anti-hypercholesterolemia drugs, which also trigger apoptosis of many cancer cell types, while docetaxel is a potent microtubule-stabilising agent.

Methods:

Here, we looked at the combined effects of lovastatin and docetaxel in cancer cells.

Results:

Whole transcriptome microarrays in HGT-1 gastric cancer cells demonstrated that lovastatin strongly suppressed expression of genes involved in cell division, while docetaxel had very little transcriptional effects. Both drugs triggered apoptosis, and their combination was more than additive. A marked rise in the cell-cycle inhibitor p21, together with reduction of aurora kinases A and B, cyclins B1 and D1 proteins was induced by lovastatin alone or in combination with docetaxel. The drug treatments induced the proteolytic cleavage of procaspase-3, a drop of the anti-apoptotic Mcl-1 protein, Poly-ADP-Ribose Polymerase and Bax. Strikingly, docetaxel-resistant HGT-1 cell derivatives overexpressing the MDR-1 gene were much more sensitive to lovastatin than docetaxel-sensitive cells.

Conclusion:

These results suggest that the association of lovastatin and docetaxel, or lovastatin alone, shows promise as plausible anticancer strategies, either as a direct therapeutic approach or following acquired P-glycoprotein-dependent resistance.

Effect of statins and anticoagulants on prostate cancer aggressiveness

PURPOSE

Statins and anticoagulants (ACs) have both been associated with a less-aggressive prostate cancer (PCa) and a better outcome after treatment of localized PCa. The results of these studies might have been confounded because patients might often take both medications. We examined their respective influence on PCa aggressiveness at initial diagnosis.

MATERIALS AND METHODS

We analyzed 381 patients treated with either external beam radiotherapy or brachytherapy for low-risk (n = 152), intermediate-risk (n = 142), or high-risk (n = 87) localized PCa. Univariate and multivariate logistic regression analyses were used to investigate an association between these drug classes and prostate cancer aggressiveness. We tested whether the concomitant use of statins and ACs had a different effect than that of either AC or statin use alone.

RESULTS

Of the 381 patients, 172 (45.1%) were taking statins and 141 (37.0%) ACs; 105 patients (27.6%) used both. On univariate analysis, the statin and AC users were associated with the prostate-specific antigen (PSA) level (p = .017) and National Comprehensive Cancer Network risk group (p = .0022). On multivariate analysis, statin use was associated with a PSA level <10 ng/mL (odds ratio, 2.9; 95% confidence interval, 1.3-6.8; p = .012) and a PSA level >20 ng/mL (odds ratio, 0.29; 95% confidence interval, 0.08-0.83; p = .03). The use of ACs was associated with a PSA level >20 ng/mL (odds ratio, 0.13; 95% confidence interval, 0.02-0.59, p = .02).

CONCLUSION

Both AC and statins have an effect on PCa aggressiveness, with statins having a more stringent relationship with the PSA level, highlighting the importance of considering statin use in studies of PCa aggressiveness.

Crocetin induces cytotoxicity and enhances vincristine-induced cancer cell death via p53-dependent and -independent mechanisms

AIM

To investigate the anticancer effect of crocetin, a major ingredient in saffron, and its underlying mechanisms.

METHODS

Cervical cancer cell line HeLa, non-small cell lung cancer cell line A549 and ovarian cancer cell line SKOV3 were treated with crocetin alone or in combination with vincristine. Cell proliferation was examined using MTT assay. Cell cycle distribution and sub-G(1) fraction were analyzed using flow cytometric analysis after propidium iodide staining. Apoptosis was detected using the Annexin V-FITC Apoptosis Detection Kit with flow cytometry. Cell death was measured based on the release of lactate dehydrogenase (LDH). The expression levels of p53 and p21(WAF1/Cip1) as well as caspase activation were examined using Western blot analysis.

RESULTS

Treatment of the 3 types of cancer cells with crocetin (60-240 μmol/L) for 48 h significantly inhibited their proliferation in a concentration-dependent manner. Crocetin (240 μmol/L) significantly induced cell cycle arrest through p53-dependent and -independent mechanisms accompanied with p21(WAF1/Cip1) induction. Crocetin (120-240 μmol/L) caused cytotoxicity in the 3 types of cancer cells by enhancing apoptosis in a time-dependent manner. In the 3 types of cancer cells, crocetin (60 μmol/L) significantly enhanced the cytotoxicity induced by vincristine (1 μmol/L). Furthermore, this synergistic effect was also detected in the vincristine-resistant breast cancer cell line MCF-7/VCR.

CONCLUSION

Ccrocetin is a potential anticancer agent, which may be used as a chemotherapeutic drug or as a chemosensitizer for vincristine.

BnRCH gene inhibits cell growth of Hela cells through increasing the G2 phase of cell cycle

The ubiquitin-proteasome pathway (UPP) is an important protein degradation system universally existing in eukaryotic organisms from yeast to human. In this system, hundreds of E3 ubiquitin-protein ligases are most important because they provide the substrate specificity and control many cellular processes. UPP has been found to be relevant to cancer development. BnRCH, the protein product from a novel gene isolated from Brassica napus, also has E3 ubiquitin-protein ligase activity. In order to exploit its potential use, human cervical carcinoma cell Hela (Hela cells) was transiently and stably transfected with BnRCH. The experimental results demonstrated: (1) in Hela cells, BnRCH inhibited the cell growth of Hela cells and increased their sensitivity to the anti-cancer chemotherapeutic drug cisplatin; and (2) the growth inhibition effect of BnRCH in Hela cells was found due to G2 phase cell cycle arrest with the transcriptional up-regulation of p21 (waf1/cip1), rather than apoptosis. This research suggests BnRCH has potential use in cancer therapy.

Cladosporol a stimulates G1-phase arrest of the cell cycle by up-regulation of p21(waf1/cip1) expression in human colon carcinoma HT-29 cells

Cladosporols, purified and characterized as secondary metabolites from Cladosporium tenuissimum, display an antifungal activity. In this study, we tested the antiproliferative properties of cladosporol A, the main isoform of this metabolite family, against human cancer cell lines. By assessing cell viability, we found that cladosporol A inhibits the growth of various human colon cancers derived cell lines (HT-29, SW480, and CaCo-2) in a time- and concentration-dependent manner, specifically of HT-29  cells. The reduced cell proliferation was due to a G1-phase arrest, as assessed by fluorescence activated cell sorting analysis on synchronized HT-29  cells, and was associated with an early and robust over-expression of p21(waf1/cip1) , the well-known cyclin-dependent kinases inhibitor. This suggests that the drug may play a role in the control of cancer cell proliferation. Consistently, cyclin D1, cyclin E, CDK2, and CDK4 proteins were reduced and histone H1-associated CDK2 kinase activity inhibited. In addition to p21(waf1/cip1) , exposure to 20 µM cladosporol A caused a simultaneous increase of pERK and pJNK, suggesting that this drug activates a circuit that integrates cell cycle regulation and the signaling pathways both involved in the inhibition of cell proliferation. Finally, we showed that the increase of p21(waf1/cip1) expression was generated by a Sp1-dependent p53-independent stimulation of its gene transcription as mutagenesis of the Sp1 binding sites located in the p21 proximal promoter abolished induction. To our knowledge, this is the first report showing that cladosporol A inhibits colon cancer cell proliferation by modulating p21(waf1/cip1) expression.

Is there a treatment advantage when paclitaxel and lovastatin are combined to dose anaplastic thyroid carcinoma cell lines?

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is the most aggressive type of thyroid carcinoma. The purpose of this study was to evaluate the combined cytotoxic effects of paclitaxel and lovastatin in ATC cell lines.

METHODS

ATC cells were treated with paclitaxel and lovastatin, separately or together, and the cytotoxicity of the compounds was determined by quantifying cell viability and apoptosis. We conducted an isobologram analysis to investigate the combined effect of the two drugs.

RESULTS

In 8505C cells, cellular viability was inhibited by lovastatin and paclitaxel in a concentration-dependent manner (p = 0.002 and p = 0.020, respectively). The IC(50) of lovastatin was 3.53 μM and that of paclitaxel was 5.98 nM. In BHT-101 cells, cellular viability was also inhibited in a concentration-dependent manner by lovastatin and paclitaxel (p = 0.020 and p = 0.032, respectively). The IC(50) of lovastatin was 17.13 μM and that of paclitaxel was 35.26 nM. In 8505C cells, paclitaxel and lovastatin alone induced apoptosis in a concentration-dependent manner. However, both an isobologram analysis on inhibition of viability and an analysis of apoptosis demonstrated antagonism between paclitaxel and lovastatin. In BHT-101 cells, however, neither drug had an apoptotic effect when used individually. There was a variable effect when used in combination, depending on the drug concentrations.

CONCLUSIONS

Paclitaxel and lovastatin were cytotoxic in two ATC cell lines and increased apoptosis in 8505C cells. However, in these cells, the combination of drugs resulted in antagonism that affected both the cytotoxicity of the compounds and the apoptosis of 8505C cells. The combination of paclitaxel and lovastatin did not enhance the treatment effect in ATC cell lines.

Statin use and risk of prostate cancer in a population of men who underwent biopsy

PURPOSE

We determined the association between statin use and prostate cancer in men who underwent prostate biopsy.

MATERIALS AND METHODS

We performed a retrospective cohort study of men who underwent prostate biopsy from 2000 to 2007 at Cleveland Clinic. Statin use was determined using outpatient pharmacy records, and clinical and pathological outcomes were obtained. Multivariate logistic regression analysis to determine the effects of statins (and duration of use) was performed after adjusting for age, body mass index, African-American race, number of cores taken and prostate volume.

RESULTS

We analyzed data from 4,204 patients, and we identified 3,182 (75.7%) not on statins and 1,022 on statins. Men diagnosed with prostate cancer on statins compared to those not taking statins were less likely to have digital rectal examination positivity (5.3% vs 8.9%, OR 0.7, p <0.01), Gleason score 7 or greater prostate cancer (61.4% vs 72.4%, OR 0.78, p = 0.02) and high volume prostate cancer (27.2 vs 31.4, p <0.01). Moreover statin users had lower prostate specific antigen compared to nonstatin users (5.13 vs 5.98, p = 0.03). Multivariate analysis adjusted risk ratios for prostate cancer diagnosis, high grade prostate cancer (Gleason score 7 or greater) and 3 or more cores positive in statin users were 0.92 (95% CI 0.85-0.98), 0.76 (95% CI 0.67-0.85) and 0.86 (95% CI 0.75-0.97) and only high grade prostate cancer persisted with length of use.

CONCLUSIONS

Statin use was associated with a decreased risk of prostate cancer, less frequent high grade prostate cancer and lower volume of prostate cancer, suggesting that statin use has a protective effect against prostate cancer.

HIF-1α depletion results in SP1-mediated cell cycle disruption and alters the cellular response to chemotherapeutic drugs

Hypoxia inducible factor (HIF) is the major transcription factor involved in the regulation of the cellular response to hypoxia, or low oxygen tensions. Even though HIF-1 function is mostly studied following hypoxic stress, well oxygenated areas of several diseased tissues have detectable levels of this transcription factor. Therefore, it is surprising how little is known about the function of HIF in normoxia. This study seeks to fill this gap. Using transient HIF-1α knockdown, as well as, stable cell lines generated using short hairpin RNAs (shRNA), we have further characterized the role of HIF-1α in normoxia. Our data reveals that knockdown of HIF-1α results in a significant increase in cells in the G1 phase of the cell cycle. We find that HIF-1α depletion increases the protein and mRNA of both p21 and p27. p21 is induced via, at least in part, p53-independent but SP1-dependent mechanisms. Interestingly, HIF-1α knockdown also alters the cellular response to chemotherapeutic agents. These data have important implications in not only for the further understanding of HIF-1α, a major transcription factor, but also for the use of HIF-targeted and combination therapies in cancer treatment.

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.

The antitumor activity of the fungicide ciclopirox

Ciclopirox olamine (CPX) is a synthetic antifungal agent clinically used to treat mycoses of the skin and nails. Here, we show that CPX inhibited tumor growth in human breast cancer MDA-MB-231 xenografts. To unveil the underlying mechanism, we further studied the antitumor activity of CPX in cell culture. The results indicate that CPX inhibited cell proliferation and induced apoptosis in human rhabdomyosarcoma (Rh30), breast carcinoma (MDA-MB231) and colon adenocarcinoma (HT-29) cells in a concentration-dependent manner. By cell cycle analysis, CPX induced accumulation of cells in G(1)/G(0) phase of the cell cycle. Concurrently, CPX downregulated cellular protein expression of cyclins (A, B1, D1 and E) and cyclin-dependent kinases (CDK2 and CDK4) and upregulated expression of the CDK inhibitor p21(Cip1), leading to hypophosphorylation of retinoblastoma protein. CPX also downregulated protein expression of Bcl-xL and survivin and enhanced cleavages of Bcl-2. Z-VAD-FMK, a pan-caspase inhibitor, partially prevented CPX-induced cell death, suggesting that CPX-induced apoptosis of cancer cells is mediated at least in part through caspase-dependent mechanism. The results indicate that CPX is a potential antitumor agent.

Statin medication use and the risk of biochemical recurrence after radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) Database

BACKGROUND

Although controversial, evidence suggests statins may reduce the risk of advanced prostate cancer (PC), and recently statin use was associated with prostate-specific antigen (PSA) reductions among men without PC. The authors sought to examine the association between statin use and PSA recurrence after radical prostatectomy (RP).

METHODS

The authors examined 1319 men treated with RP from the Shared Equal Access Regional Cancer Hospital (SEARCH) Database. Time to PSA recurrence was compared between users and nonusers of statin at surgery using Cox proportional hazards models adjusted for multiple clinical and pathological features.

RESULTS

In total, 236 (18%) men were taking statins at RP. Median follow-up was 24 months for statin users and 38 for nonusers. Statin users were older (P<.001) and underwent RP more recently (P<.001). Statin users were diagnosed at lower clinical stages (P=.009) and with lower PSA levels (P=.04). However, statin users tended to have higher biopsy Gleason scores (P=.002). After adjusting for multiple clinical and pathological factors, statin use was associated with a 30% lower risk of PSA recurrence (hazard ratio "HR", 0.70; 95% confidence interval "CI", 0.50-0.97; P=.03), which was dose dependent (relative to no statin use; dose equivalent<simvastatin 20 mg: HR, 1.08; 95% CI, 0.66-1.73; P=.78; dose equivalent=simvastatin 20 mg: HR, 0.57; 95% CI, 0.32-1.00; P=.05; dose equivalent>simvastatin 20 mg: HR, 0.50; 95% CI, 0.27-0.93; P=.03).

CONCLUSIONS

In this cohort of men undergoing RP, statin use was associated with a dose-dependent reduction in the risk of biochemical recurrence. If confirmed in other studies, these findings suggest statins may slow PC progression after RP.

Novel synthetic inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity that inhibit tumor cell proliferation and are structurally unrelated to existing statins

Pilot-scale libraries of eight-membered medium ring lactams (MRLs) and related tricyclic compounds (either seven-membered lactams, thiolactams or amines) were screened for their ability to inhibit the catalytic activity of human recombinant 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase in vitro. A dozen of the synthetic compounds mimic the inhibition of purified HMG-CoA reductase activity caused by pravastatin, fluvastatin and sodium salts of lovastatin, mevastatin and simvastatin in this cell-free assay, suggesting direct interaction with the rate-limiting enzyme of cholesterol biosynthesis. Moreover, several MRLs inhibit the metabolic activity of L1210 tumor cells in vitro to a greater degree than fluvastatin, lovastatin, mevastatin and simvastatin, whereas pravastatin is inactive. Although the correlation between the concentration-dependent inhibitions of HMG-CoA reductase activity over 10 min in the cell-free assay and L1210 tumor cell proliferation over 4 days in culture is unclear, some bioactive MRLs elicit interesting combinations of statin-like (IC50: 7.4-8.0 microM) and anti-tumor (IC50: 1.4-2.3 microM) activities. The HMG-CoA reductase-inhibiting activities of pravastatin and an MRL persist in the presence of increasing concentrations of NADPH. But increasing concentrations of HMG-CoA block the HMG-CoA reductase-inhibiting activity of pravastatin without altering that of an MRL, suggesting that MRLs and existing statins may have different mechanisms of enzyme interaction and inhibition. When tested together, suboptimal concentrations of synthetic MRLs and existing statins have additive inhibitory effects on HMG-CoA reductase activity. Preliminary molecular docking studies with MRL-based inhibitors indicate that these ligands fit sterically well into the HMG-CoA reductase statin-binding receptor model and, in contrast to mevastatin, may occupy a narrow channel housing the pyridinium moiety on NADP+.

Statin use and risk of colorectal cancer in a cohort of middle-aged men in the US: a prospective cohort study

BACKGROUND

Numerous modifiable factors have been associated with a reduced risk of colorectal cancer, including the chronic use of NSAIDs. Thus, it is biologically plausible that HMG-CoA reductase inhibitors (statins), therapeutic agents that also possess anti-inflammatory effects, are also associated with a lowered risk of colorectal cancer.

OBJECTIVE

To examine the association between statin use and the risk of colorectal cancer in a large cohort of middle-aged men enrolled in a prepaid, integrated health maintenance organization.

METHODS

We conducted a prospective cohort study of 69 115 Northern and Southern California Kaiser Permanente (KP) members aged 45-69 years who enrolled in the California Men's Health Study in 2002-3. Colorectal cancer cases were identified by linkage to the KP California Cancer Registries. Statin exposure, estimated from automated KP outpatient pharmacy records (available since 1991 in Southern California and 1994 in Northern California), was treated as time-varying. Cox proportional hazards regression analyses were used to estimate hazard ratios and 95% confidence intervals (CIs), while controlling for potential confounders.

RESULTS

During a maximum of 3.5 years of follow-up, 171 colorectal cancer cases were identified. Compared with nonuse, the adjusted hazard ratio for ever use of statins was 0.89 (95% CI 0.61, 1.30). The hazard ratio for statin use of >or=5 years was 0.83 (95% CI 0.43, 1.63). The results did not differ markedly by type or severity of disease. There was also no evidence of effect modification by regular NSAID use. However, the stratified analyses were limited by small numbers.

CONCLUSION

These findings provide little support for an association between the use of statins and the risk of colorectal cancer in men. There was some suggestion of a modest inverse association between statin use for >or=5 years and risk of colorectal cancer; however, the possibility that this observation may be related to regular NSAID use cannot be ruled out.

Increased low density lipoprotein and increased likelihood of positive prostate biopsy in black americans

PURPOSE

Differences in prostate cancer incidence, grade and stage at diagnosis, and survival in black vs nonblack men are well documented. Recent studies indicate that lipids may have a role in oncogenesis, including that of prostate cancer. We investigated the relationship between circulating lipids in black and nonblack patients, and newly diagnosed prostate cancer.

MATERIALS AND METHODS

The study population included consecutive patients who underwent prostate biopsy for increased prostate specific antigen and/or abnormal digital rectal examination at Atlanta Veterans Affairs Medical Center. Age, race, prostate specific antigen, prostate volume, body mass index, family history, high and low density lipoprotein, triglyceride and cholesterol lowering medications were included in data analysis.

RESULTS

A total of 1,775 men with complete information were included in data analysis. A total of 521 black and 451 white men had positive biopsies. Using 100 mg/dl or less as the referent the adjusted OR reflecting the association of low density lipoprotein and prostate cancer diagnosis in black men was 1.49 (95% CI 1.04-2.13, p = 0.031), 1.51 (95% CI 0.96-2.39, p = 0.076) and 3.24 (95% CI 1.59-6.92, p = 0.002) for low density lipoprotein greater than 100 to 130, greater than 130 to 160 and greater than 160 mg/dl, respectively. Corresponding results in nonblack men showed no significant association.

CONCLUSIONS

Increased serum low density lipoprotein is associated with an increased likelihood of prostate cancer diagnosis in black men but not in nonblack men. This association is strongest in the highest low density lipoprotein risk category. The reasons for the racial differences are unknown but may include genetic, dietary or other environmental factors.

Statin Use and Cancer Risk: An Epidemiologic Review

While the beneficial effects of hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on cardiovascular disease are well established, much uncertainty remains about their effects on cancer. The statins inhibit the rate-limiting step in the mevalonate pathway, leading to reduced levels of cholesterol and other molecules of importance for critical cellular processes. A growing body of preclinical data indicates that statins may have antineoplastic properties, but some studies raise the possibility that statins may possess a carcinogenic potential. Clinical and observational studies of the association between statin use and cancer have been inconclusive with regard to any chemopreventive or therapeutic effect, but they do provide reassuring evidence that statins do not appear to be carcinogenic. The reasons for the varying results are unclear but they may relate to methodological issues. Additional studies, including Phase II randomized trials and epidemiological studies with accurate measures of statin use and comprehensive control for confounding factors, are needed to determine the potentially beneficially effects of statins on cancer development and progression.

Inhibition of tumor cell motility by the interferon-inducible GTPase MxA

To identify pathways controlling prostate cancer metastasis we performed differential display analysis of the human prostate carcinoma cell line PC-3 and its highly metastatic derivative PC-3M. This revealed that a 78-kDa interferon-inducible GTPase, MxA, was expressed in PC-3 but not in PC-3M cells. The gene encoding MxA, MX1, is located in the region of chromosome 21 deleted as a consequence of fusion of TMPRSS2 and ERG, which has been associated with aggressive, invasive prostate cancer. Stable exogenous MxA expression inhibited in vitro motility and invasiveness of PC-3M cells. In vivo exogenous MxA expression decreased the number of hepatic metastases following intrasplenic injection. Exogenous MxA also reduced motility and invasiveness of highly metastatic LOX melanoma cells. A mutation in MxA that inactivated its GTPase reversed inhibition of motility and invasion in both tumor cell lines. Co-immunoprecipitation studies demonstrated that MxA associated with tubulin, but the GTPase-inactivating mutation blocked this association. Because MxA is a highly inducible gene, an MxA-targeted drug discovery screen was initiated by placing the MxA promoter upstream of a luciferase reporter. Examination of the NCI diversity set of small molecules revealed three hits that activated the promoter. In PC-3M cells, these drugs induced MxA protein and inhibited motility. These data demonstrate that MxA inhibits tumor cell motility and invasion, and that MxA expression can be induced by small molecules, potentially offering a new approach to the prevention and treatment of metastasis.

UHRF1 binds G9a and participates in p21 transcriptional regulation in mammalian cells

UHRF1 (ubiquitin-like, containing PHD and RING finger domains 1) is a multi-domain protein associated with cellular proliferation and epigenetic regulation. The UHRF1 binds to methylated CpG dinucleotides and recruits transcriptional repressors DNA methyltransferase 1 (DNMT1) and histone deacetylase 1 (HDAC1) through its distinct domains. However, the molecular basis of UHRF1-mediated transcriptional regulation via chromatin modifications is yet to be fully understood. Here we show that UHRF1 binds histone lysine methyltransferase G9a, and both are co-localized in the nucleus in a cell-cycle-dependent manner. Concurrent with the cell-cycle progression, gradual deposition of UHRF1 and G9a was observed, which mirrored H3K9me2 accumulation on chromatin. Murine Uhrf1-null embryonic stem (ES) cells displayed a reduced amount of G9a and H3K9me2 on chromatin. UHRF1 recruited and cooperated with G9a to inhibit the p21 promoter activity, which correlated with the elevated p21 protein level in both human UHRF1 siRNA-transfected HeLa cells and murine Uhrf1-null ES cells. Furthermore, endogenous p21 promoter remained bound to UHRF1, G9a, DNMT1 and HDAC1, and knockdown of UHRF1 impaired the association of all three chromatin modifiers with the promoter. Thus, our results suggest that UHRF1 may serve as a focal point of transcriptional regulation mediated by G9a and other chromatin modification enzymes.

Statins and cancer: a meta-analysis of case-control studies

3-HMG-CoA reductase inhibitors (statins) block the growth of malignant cells in vitro. A meta-analysis of randomized controlled trials failed to show reduced risk of cancers in statin users. Case-control studies, however, have the advantage of examining remote exposures. This study determined the association between statins and breast cancer, colon cancer, lung cancer, prostate cancer, or any cancer in case-control studies. A comprehensive search for studies published through November 2006 was performed. Twenty case-control studies (100 129 incident cancer cases) were combined to obtain a pooled odds ratio using an inverse variance method. A funnel plot did not suggest a significant absence of unpublished data. The studies were significantly heterogeneous (P<0.01), thus a random effects model was used. The pooled OR and 95% confidence intervals for statin users and cancer were as follows: any cancer 0.71 (0.56-0.89), breast cancer 0.86 (0.60-1.23), colon cancer 0.89 (0.82-0.97), lung cancer 0.75 (0.50-1.11), and prostate cancer 0.74 (0.45-1.20). In this meta-analysis of case-control studies, we found a significant association between statin usage and any cancer, but when stratified by cancer type, only the association with colon cancer remained. On the basis of these results, randomized control trials with longer follow-up times than previously used are warranted.

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

Statins are cholesterol-lowering drugs that are widely used to prevent and treat atherosclerotic cardiovascular disease. Recent research from both in vitro and in vivo studies suggests that there is an association between the use of statins and a reduction in the incidence of and mortality from prostate cancer. Several mechanisms of action that might bring about these beneficial effects of statins have been proposed, most of which include direct effects of statins on intracellular signaling. In this Review we discuss the current knowledge on the use of statins to prevent prostate cancer. We will also look at future directions for clinical research on this topic.