Ashraful Hoque

Statin induces apoptosis and cell growth arrest in prostate cancer cells.

Statins are a class of low molecular weight drugs that inhibit the rate-limiting enzyme of the mevalonate pathway 3-hydroxy-3-methylglutaryl-CoA reductase. Statins have been approved and effectively used to control hypercholesterolemia in clinical setting. Recent study showed statins antitumor activity and suggested a potential role for prevention of human cancers. In this study, we did cell viability, DNA fragmentation, and terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling assays to evaluate the action of statins on prostate cancer cells and used Western blotting and RhoA activation assay to investigate the underlying molecular mechanism of action. Our data showed that lovastatin and simvastatin effectively decreased cell viability in three prostate cancer cell lines (PC3, DU145, and LnCap) by inducing apoptosis and cell growth arrest at G1 phase. Both lovastatin and simvastatin induced activation of caspase-8, caspase-3, and, to a lesser extent, caspase-9. Both statins suppressed expression of Rb, phosphorylated Rb, cyclin D1, cyclin D3, CDK4, and CDK6, but induced p21 and p27 expression in prostate cancer cells. Furthermore, lovastatin and simvastatin suppressed RhoA activation and c-JUN expression, but not cyclooxygenase-2 expression. Our data showed that the antitumor activity of statins is due to induction of apoptosis and cell growth arrest. The underlying molecular mechanism of statins action is mediated through inactivation of RhoA, which in turn induces caspase enzymatic activity and/or G1 cell cycle. Future studies should focus on examining statins and other apoptosis-inducing drugs (e.g., cyclooxygenase-2 inhibitors or curcumin) together to assess their efficacy in prevention of prostate cancer. (Cancer Epidemiol Biomarkers Prev 2008;17(1):88–94)

Prognostic significance of differentially expressed miRNAs in esophageal cancer

Altered microRNA (miRNA) expression has been found to promote carcinogenesis, but little is known about the role of miRNAs in esophageal cancer. In this study, we selected 10 miRNAs and analyzed their expression in 10 esophageal cancer cell lines and 158 tissue specimens using Northern blotting and in situ hybridization, respectively. We found that Let‐7g, miR‐21 and miR‐195p were expressed in all 10 cell lines, miR‐9 and miR‐20a were not expressed in any of the cell lines, and miR‐16‐2, miR‐30e, miR‐34a, miR‐126 and miR‐200a were expressed in some of the cell lines but not others. In addition, transient transfection of miR‐34a inhibited c‐Met and cyclin D1 expression and esophageal cancer cell proliferation, whereas miR‐16‐2 suppressed RAR‐β2 expression and increased tumor cell proliferation. Furthermore, we found that miR‐126 expression was associated with tumor cell dedifferentiation and lymph node metastasis, miR‐16‐2 was associated with lymph node metastasis, and miR‐195p was associated with higher pathologic disease stages in patients with esophageal adenocarcinoma. Kaplan‐Meier analysis showed that miR‐16‐2 expression and miR‐30e expression were associated with shorter overall and disease‐free survival in all esophageal cancer patients. In addition, miR‐16‐2, miR‐30e and miR‐200a expression were associated with shorter overall and disease‐free survival in patients with esophageal adenocarcinoma; however, miR‐16‐2, miR‐30e and miR‐200a expression were not associated with overall or disease‐free survival in squamous cell carcinoma patients. Our data indicate that further evaluation of miR‐30e and miR‐16‐2 as prognostic biomarkers is warranted in patients with esophageal adenocarcinoma. In addition, the role of miR‐34a in esophageal cancer also warrants further study.

Chronic Inflammation in Benign Prostate Tissue Is Associated with High-Grade Prostate Cancer in the Placebo Arm of the Prostate Cancer Prevention Trial

Background: Chronic inflammation is hypothesized to influence prostate cancer development, although a definitive link has not been established. Methods: Prostate cancer cases (N = 191) detected on a for-cause (clinically indicated) or end-of-study (protocol directed) biopsy, and frequency-matched controls (N = 209), defined as negative for cancer on an end-of-study biopsy, were sampled from the placebo arm of the Prostate Cancer Prevention Trial. Inflammation prevalence and extent in benign areas of biopsy cores were visually assessed using digital images of hematoxylin and eosin–stained sections. Logistic regression was used to estimate associations. Results: Of note, 86.2% of cases and 78.2% of controls had at least one biopsy core (of three assessed) with inflammation in benign areas, most of which was chronic. Men who had at least one biopsy core with inflammation had 1.78 [95% confidence interval (CI), 1.04–3.06] times the odds of prostate cancer compared with men who had zero cores with inflammation. The association was stronger for high-grade disease (Gleason sum 7–10, N = 94; OR, 2.24; 95% CI, 1.06–4.71). These patterns were present when restricting to cases and controls in whom intraprostatic inflammation was the least likely to have influenced biopsy recommendation because their prostate-specific antigen (PSA) was low (<2 ng/mL at biopsy). Conclusion: Inflammation, most of which was chronic, was common in benign prostate tissue, and was positively associated with prostate cancer, especially high grade. The association did not seem to be due to detection bias. Impact: This study supports an etiologic link between inflammation and prostate carcinogenesis, and suggests an avenue for prevention by mitigating intraprostatic inflammation. Cancer Epidemiol Biomarkers Prev; 23(5); 847–56. ©2014 AACR.

Cancer among a Michigan cohort exposed to polybrominated biphenyls in 1973

The long-term health effects of human exposure to polybrominated biphenyls are not known. In this nested case-control study, we evaluated the association between site-specific cancer risk and serum polybrominated biphenyl levels among a Michigan cohort accidentally exposed to polybrominated biphenyls in 1973. The Michigan Department of Public Health has followed 3,899 people through 1993, among whom 195 primary cancers were identified in 187 persons. Controls were 696 randomly selected cancer-free individuals who were frequency matched to cases by sex and age (in 5-year strata). Baseline serum polybrominated biphenyl levels were measured using standard methods. We found an increasing dose-response relation for digestive system cancer risk with higher serum polybrominated biphenyl category [4–20 parts per billion (ppb), 21–50 ppb, and >50 ppb] after adjustment for age, family cancer history, cigarette smoking, alcohol drinking, and baseline serum polychlorinated biphenyl level. Adjusted odds ratios (ORs) for each category were 8.23 [95% confidence interval (CI) = 1.27–53.3], 12.3 (95% CI = 0.80–191), and 22.9 (95% CI = 1.34–392), respectively. Univariate analysis for polybrominated biphenyl level and lymphoma risk also showed a dose-response relation, with corresponding ORs of 3.24 (95% CI = 0.24–95.9), 20.5 (95% CI = 1.51–608), and 32.6 (95% CI = 3.33–861). (Epidemiology 1998;9:373–378)

Single nucleotide differences (SNDs) in the dbSNP database may lead to errors in genotyping and haplotyping studies.

The creation of single nucleotide polymorphism (SNP) databases (such as NCBI dbSNP) has facilitated scientific research in many fields. SNP discovery and detection has improved to the extent that there are over 17 million human reference (rs) SNPs reported to date (Build 129 of dbSNP). SNP databases are unfortunately not always complete and/or accurate. In fact, half of the reported SNPs are still only candidate SNPs and are not validated in a population. We describe the identification of SNDs (single nucleotide differences) in humans, that may contaminate the dbSNP database. These SNDs, reported as real SNPs in the database, do not exist as such, but are merely artifacts due to the presence of a paralogue (highly similar duplicated) sequence in the genome. Using sequencing we showed how SNDs could originate in two paralogous genes and evaluated samples from a population of 100 individuals for the presence/absence of SNPs. Moreover, using bioinformatics, we predicted as many as 8.32% of the biallelic, coding SNPs in the dbSNP database to be SNDs. Our identification of SNDs in the database will allow researchers to not only select truly informative SNPs for association studies, but also aid in determining accurate SNP genotypes and haplotypes. Hum Mutat 31:67–73, 2010.

Androgen Receptor CAG Repeat Length and Association With Prostate Cancer Risk: Results From the Prostate Cancer Prevention Trial

PURPOSE We investigated the association between the length of the polymorphic trinucleotide CAG microsatellite repeats in exon 1 of the AR gene and the risk of prostate cancer. MATERIALS AND METHODS This is a nested case-control study of 1,159 cases and 1,353 controls from the Prostate Cancer Prevention Trial, a randomized, placebo controlled trial testing whether the 5α-reductase inhibitor finasteride could decrease the 7-year prevalence of prostate cancer. During the course of the trial men underwent annual digital rectal examination and prostate specific antigen measurement. Prostate biopsy was recommended in all men with abnormal digital rectal examination or finasteride adjusted prostate specific antigen greater than 4.0 ng/ml. Cases were drawn from men with biopsy determined prostate cancer identified by for cause or end of study biopsy. Controls were selected from men who completed the end of study biopsy. RESULTS Mean CAG repeat length did not differ between cases and controls. The frequency distribution of cases and controls for the AR CAG repeat length was similar. There were no significant associations of CAG repeat length with prostate cancer risk when stratified by treatment arm (finasteride or placebo), or when combined. There was also no significant association between CAG repeat length and the risk of low or high grade prostate cancer. CONCLUSIONS There is no association of AR CAG repeat length with prostate cancer risk. Knowledge of AR CAG repeat length provides no clinically useful information to predict prostate cancer risk.

Finasteride modifies the relation between serum C-peptide and prostate cancer risk: results from the Prostate Cancer Prevention Trial

Hyperinsulinemia and obesity-related metabolic disturbances are common and have been associated with increased cancer risk and poor prognosis. To investigate this issue in relation to prostate cancer, we conducted a nested case-control study within the Prostate Cancer Prevention Trial (PCPT), a randomized, placebo-controlled trial testing finasteride versus placebo for primary prevention of prostate cancer. Cases (n = 1,803) and controls (n = 1,797) were matched on age, PCPT treatment arm, and family history of prostate cancer; controls included all eligible non-whites. Baseline bloods were assayed for serum C-peptide (marker of insulin secretion) and leptin (an adipokine) using ELISA. All outcomes were biopsy determined. Logistic regression calculated odds ratios (OR) for total prostate cancer and polytomous logistic regression calculated ORs for low-grade (Gleason <7) and high-grade (Gleason >7) disease. Results were stratified by PCPT treatment arm for C-peptide. For men on placebo, higher versus lower serum C-peptide was associated with a nearly 2-fold increased risk of high-grade prostate cancer (Gleason >7; multivariate-adjusted OR, 1.88; 95% confidence interval, 1.19–2.97; Ptrend = 0.004). When C-peptide was modeled as a continuous variable, every unit increase in log(C-peptide) resulted in a 39% increased risk of high-grade disease (P = 0.01). In contrast, there was no significant relationship between C-peptide and high-grade prostate cancer among men receiving finasteride. Leptin was not independently associated with high-grade prostate cancer. In conclusion, these results support findings from other observational studies that high serum C-peptide and insulin resistance, but not leptin, are associated with increased risk of high-grade prostate cancer. Our novel finding is that the C-peptide–associated risk was attenuated by use of finasteride. Cancer Prev Res; 3(3); 279–89

Inhibition of farnesoid X receptor controls esophageal cancer cell growth in vitro and in nude mouse xenografts

Gastroesophageal reflux is a risk factor for esophageal adenocarcinoma, and bile acid and its farnesoid X receptor (FXR) have been implicated in esophageal tumorigenesis. The authors investigated the role of FXR expression and activity in esophageal cancer initiation and growth.

Human Papillomavirus Types 16, 18, and 31 Serostatus and Prostate Cancer Risk in the Prostate Cancer Prevention Trial

Since human papillomavirus (HPV) infection was first identified as a risk factor for cervical cancer, several seroepidemiologic and tissue-based studies have investigated HPV in relation to prostate cancer, another common genitourinary malignancy, with mixed results. To further inform this potential association, we conducted a large, prospective investigation of HPV types 16, 18, and 31 in relation to risk of prostate cancer in the Prostate Cancer Prevention Trial. Cases were a sample of men diagnosed with prostate cancer after visit 2 or on their end-of-study biopsy (n = 616). Controls were men not diagnosed with prostate cancer during the trial or on their end-of-study biopsy (n = 616). Controls were frequency matched to cases by age, treatment arm, and family history of prostate cancer. Sera from visit 2 were tested for IgG antibodies against HPV types 16, 18, and 31. No associations were observed for weak or strong HPV-16 [odds ratio (OR), 0.94; 95% confidence interval (95% CI), 0.53-1.64 and OR, 1.07; 95% CI, 077-1.48, respectively], HPV-18 (OR, 0.75; 95% CI, 0.27-2.04 and OR, 0.87; 95% CI, 0.47-1.63, respectively), or HPV-31 seropositivity (OR, 0.76; 95% CI, 0.45-1.28 and OR, 1.15; 95% CI, 0.80-1.64, respectively) and risk of prostate cancer. Considering this finding in the context of the HPV and prostate cancer literature, HPV does not appear to be associated with risk of prostate cancer, at least by mechanisms proposed to date, and using epidemiologic designs and laboratory techniques currently available. Cancer Epidemiol Biomarkers Prev; 19(2); 614–8

Centralized Blood Processing for the Selenium and Vitamin E Cancer Prevention Trial: Effects of Delayed Processing on Carotenoids, Tocopherols, Insulin-Like Growth Factor-I, Insulin-Like Growth Factor Binding Protein 3, Steroid Hormones, and Lymphocyte Viability

This experiment examined the effects of delays in separation and freezing of whole blood components on analytes of interest in studies of prostate cancer prevention, in order to evaluate the feasibility of centralized processing of blood for the multisite Selenium and Vitamin E Cancer Prevention Trial. Blood from 40 healthy men was subjected to four treatment protocols, allowing the contrast of immediate processing to delays of 32, 72, and 144 hours. At 32 hours, simulating refrigerated storage and overnight shipping, there was a 2.9% decrease (95% confidence interval, 0.7-5.1) in insulin-like growth factor-I (IGF-I) but no significant change in carotenoids, tocopherols, testosterone, 3α-androstanediol glucuronide (AAG), sex hormone–binding globulin (SHBG) or insulin-like growth factor binding protein 3 (IGFBP3). A 144-hour processing delay, simulating weekend blood collection or shipping delay, resulted in significant changes in γ-tocopherol (−1.5%), IGF-I (−5.7%), IGFBP3 (−2.9%), SHBG (−4.0%), testosterone (+4.7%), and AAG (+5.5%). The rank-order and intraclass correlations between analytes from blood processed immediately and those subjected to delayed processing were 0.96 or higher for carotenoids, tocopherols, AAG, and SHBG, and between 0.87 and 0.95 for IGF-I, IGFBP3, and testosterone. A 32-hour delay decreased lymphocyte viability from 82.5% to 75.0% (P = 0.45), but a 72-hour delay decreased viability to 36.8% (P < 0.001). Overnight shipping and centralized processing is an acceptable approach to blood collection in large multisite trials examining the cancer-related measures proposed in the Selenium and Vitamin E Cancer Prevention Trial. Longer processing delays, however, have small but statistically significant effects on many analytes and substantially decrease lymphocyte viability.