Genetic polymorphisms in CYP17, CYP3A4, CYP19A1, SRD5A2, IGF-1, and IGFBP-3 and prostate cancer risk in African-American men: the Flint Men's Health Study

Predicting biochemical-recurrence-free survival using a three-metabolic-gene risk score model in prostate cancer patients

BACKGROUND

Biochemical recurrence (BCR) after initial treatment, such as radical prostatectomy, is the most frequently adopted prognostic factor for patients who suffer from prostate cancer (PCa). In this study, we aimed to construct a prognostic model consisting of gene expression profiles to predict BCR-free survival.

METHODS

We analyzed 70 metabolic pathways in 152 normal prostate samples and 494 PCa samples from the UCSC Xena dataset (training set) via gene set enrichment analysis (GSEA) to select BCR-related genes and constructed a BCR-related gene risk score (RS) model. We tested the power of our model using Kaplan-Meier (K-M) plots and receiver operator characteristic (ROC) curves. We performed univariate and multivariate analyses of RS using other clinicopathological features and established a nomogram model, which has stronger prediction ability. We used GSE70770 and DFKZ 2018 datasets to validate the results. Finally, we performed differential expression and quantitative real-time polymerase chain reaction analyses of the UCSC data for further verification of the findings.

RESULTS

A total of 194 core enriched genes were obtained through GSEA, among which 16 BCR-related genes were selected and a three-gene RS model based on the expression levels of CA14, LRAT, and MGAT5B was constructed. The outcomes of the K-M plots and ROC curves verified the accuracy of the RS model. We identified the Gleason score, pathologic T stage, and RS model as independent predictors through univariate and multivariate Cox analyses and constructed a nomogram model that presented better predictability than the RS model. The outcomes of the validation set were consistent with those of the training set. Finally, the results of differential expression analyses support the effectiveness of our model.

CONCLUSION

We constructed an RS model based on metabolic genes that could predict the prognosis of PCa patients. The model can be easily used in clinical applications and provide important insights into future research on the underlying mechanism of PCa.

Germline Predisposition to Prostate Cancer in Diverse Populations

There remains a paucity of data related to germline genetic alterations predisposing patients to prostate cancer. Recent data suggest that African American, Hispanic, and Asian and Pacific Islander men exhibit genetic alterations in both highly penetrant germline genes, including BRCA1/2, ATM, and CHEK2, and the mismatch repair genes associated with Lynch syndrome, as well as low-penetrant single-nucleotide polymorphisms. However, cohort sizes remain small in many studies limiting the ability to determine clinical significance, appropriate risk stratification, and treatment implications in these diverse populations.

The CYP19A1 (TTTA)n Repeat Polymorphism May Affect the Prostate Cancer Risk: Evidence from a Meta-Analysis

Abnormal aromatase (CYP19A1) expression may participate in prostate cancer (PCa) carcinogenesis. However, the results of studies on the CYP19A1 gene polymorphisms and PCa are conflicting. This meta-analysis aimed to systematically evaluate the associations between the CYP19A1 Arg264Cys polymorphism and the (TTTA)n repeat polymorphism and PCa. Electronic databases (PubMed, EmBase, ScienceDirect, and Cochrane Library) were comprehensively searched to identify eligible studies. The strength of the association between the Arg264Cys polymorphism and PCa was assessed by pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) in allelic, dominant, recessive, homozygous, and heterozygous genetic models. To analyze the impact of the (TTTA)n repeat polymorphism, we sequentially took the N-repeat allele (where N equals 7,8,10,11,12, and 13) as the minor allele and the sum of all the other alleles as the major allele. The ORs and 95% CIs were calculated in the allelic model; this analysis was performed individually for each repeat number. Pooled estimates of nine studies addressing the Arg264Cys polymorphism indicated that this polymorphism was not associated with PCa risk in the overall population or in the Caucasian or Asian subgroups. The 8-repeat allele in the (TTTA)n repeat polymorphism increased PCa risk in the overall population (OR = 1.34, 95% CI = 1.14-1.58, p = .001) and in the subgroup with population-based (PB) controls (OR = 1.41, 95% CI = 1.13-1.74, p = .002) as well as in the subgroup using capillary electrophoresis to identify this polymorphism (OR = 1.34, 95% CI = 1.09-1.65, p = .006).The meta-analysis indicated that the CYP19A1 (TTTA)n repeat polymorphism, but not the Arg264Cys polymorphism, may affect PCa risk.

The Impact of African Ancestry on Prostate Cancer Disparities in the Era of Precision Medicine

Prostate cancer disproportionately affects men of African ancestry at nearly twice the rate of men of European ancestry despite the advancement of treatment strategies and prevention. In this review, we discuss the underlying causes of these disparities including genetics, environmental/behavioral, and social determinants of health while highlighting the implications and challenges that contribute to the stark underrepresentation of men of African ancestry in clinical trials and genetic research studies. Reducing prostate cancer disparities through the development of personalized medicine approaches based on genetics will require a holistic understanding of the complex interplay of non-genetic factors that disproportionately exacerbate the observed disparity between men of African and European ancestries.

Polymorphism in the Androgen Biosynthesis Gene (CYP17), a Risk for Prostate Cancer: A Meta-Analysis

Gene polymorphism is one of the few factors that increases the risk of prostate cancer. T to C substitution in the 5’ promoter region of the CYP17 gene is hypothesized to increase the rate of gene transcription, increase androgen production, and thereby increase the risk of prostate cancer. Nevertheless, the inconsistencies originating from studies on CYP17 polymorphism and prostate cancer prompted this meta-analysis, to decipher the association between CYP17 polymorphism and prostate cancer. Most case-control studies addressing CYP17 polymorphism and prostate cancer were exhaustively searched from Web of Science, Google Scholar, and PubMed. The various genotype distributions as well as the minor allele distributions were retrieved. Pooled odds ratios (ORs) with their 95% CI and estimates of the Hardy–Weinberg Equilibrium were calculated. Analyses were performed using the RevMan v.5.3 software and SPSS v.21. There was high-pooled heterogeneity (I² = 87.0%, OR = .42, CI [.39, .45], and p < .001) among the A2 versus A1 allele. With the per-allele model (A2 versus A1), ethnicity was a major risk factor to prostate cancer, with Asians recording the highest risk (OR = 12.61, 95% CI [8.77, 18.12]). From the genotype models, A1/A1 versus A2/A2 (OR = 3.02, 95% CI [2.65, 3.44]) and A1/A2 versus A2/A2 (OR = 4.39, 95% CI [3.86, 5.00]) were all significantly associated with prostate cancer. Although some genotype models were associated with the risk of prostate cancer, we should be mindful when interpreting the results of this study because of the limited number of studies and the small sample size used.

The role of insulin-like growth factors in the development of prostate cancer

INTRODUCTION

Preclinical, clinical, and population studies have provided robust evidence for an important role for the insulin-like growth factor (IGF) system in the development of prostate cancer.

AREAS COVERED

An overview of the IGF system is provided. The evidence implicating the IGF system in the development of prostate cancer is summarized. The compelling evidence culminated in a number of clinical trials of agents targeting the system; the reasons for the failure of these trials are discussed.

EXPERT OPINION

Clinical trials of agents targeting the IGF system in prostate cancer were terminated due to limited objective clinical responses and are unlikely to be resumed unless a convincing predictive biomarker is identified that would enable the selection of likely responders. The aging population and increased screening will lead to greater diagnosis of prostate cancer. Although the vast majority will be indolent disease, the epidemics of obesity and diabetes will increase the proportion that progress to clinical disease. The increased population of worried men will result in more trials aimed to reduce the risk of disease progression; actual clinical endpoints will be challenging and the IGFs remain the best intermediate biomarkers to indicate a response that could alter the course of disease.

Association Between CYP17A1, CYB5A Polymorphisms and Efficacy of Abiraterone Acetate/Prednisone Treatment in Castration-Resistant Prostate Cancer Patients

PURPOSE

The purpose of this study was to investigate the association between single nucleotide polymorphisms (SNPs) of CYP17A1, CYB5A and the efficacy of abiraterone acetate treatment in patients with castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

Data were collected from 58 CRPC patients who had been treated with abiraterone acetate/prednisone (AA/P). The SNPs rs743572 and rs10883783 on CYP17A1 and SNPs rs1790834 and rs1790858 on CYB5A were assayed, and their relationship with prostate-specific antigen (PSA) response in patients after AA/P treatment, overall survival (OS) and progression-free survival (PFS) were analyzed by logistic regression, Cox regression, Kaplan-Meier and Log rank analyses.

RESULTS

The SNP rs1790834 on CYB5A showed significant association with PSA response in CRPC patients treated with AA/P (P < 0.05), but rs743572, rs10883783 and rs1790858 did not. The rs1790834 variant significantly decreased both PFS and OS (P < 0.05).

CONCLUSION

The CYB5A rs790834 genotype is a novel SNP related to CRPC and may be used as a biomarker for CRPC treatment.

Epidemiology of Prostate Cancer

Prostate cancer is the second most frequent cancer diagnosis made in men and the fifth leading cause of death worldwide. Prostate cancer may be asymptomatic at the early stage and often has an indolent course that may require only active surveillance. Based on GLOBOCAN 2018 estimates, 1,276,106 new cases of prostate cancer were reported worldwide in 2018, with higher prevalence in the developed countries. Differences in the incidence rates worldwide reflect differences in the use of diagnostic testing. Prostate cancer incidence and mortality rates are strongly related to the age with the highest incidence being seen in elderly men (> 65 years of age). African-American men have the highest incidence rates and more aggressive type of prostate cancer compared to White men. There is no evidence yet on how to prevent prostate cancer; however, it is possible to lower the risk by limiting high-fat foods, increasing the intake of vegetables and fruits and performing more exercise. Screening is highly recommended at age 45 for men with familial history and African-American men. Up-to-date statistics on prostate cancer occurrence and outcomes along with a better understanding of the etiology and causative risk factors are essential for the primary prevention of this disease.

Does milk intake promote prostate cancer initiation or progression via effects on insulin-like growth factors (IGFs)? A systematic review and meta-analysis

PURPOSE

To establish whether the association between milk intake and prostate cancer operates via the insulin-like growth factor (IGF) pathway (including IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3).

METHODS

Systematic review, collating data from all relevant studies examining associations of milk with IGF, and those examining associations of IGF with prostate cancer risk and progression. Data were extracted from experimental and observational studies conducted in either humans or animals, and analyzed using meta-analysis where possible, with summary data presented otherwise.

RESULTS

One hundred and seventy-two studies met the inclusion criteria: 31 examining the milk-IGF relationship; 132 examining the IGF-prostate cancer relationship in humans; and 10 animal studies examining the IGF-prostate cancer relationship. There was moderate evidence that circulating IGF-I and IGFBP-3 increase with milk (and dairy protein) intake (an estimated standardized effect size of 0.10 SD increase in IGF-I and 0.05 SD in IGFBP-3 per 1 SD increase in milk intake). There was moderate evidence that prostate cancer risk increased with IGF-I (Random effects meta-analysis OR per SD increase in IGF-I 1.09; 95% CI 1.03, 1.16; n = 51 studies) and decreased with IGFBP-3 (OR 0.90; 0.83, 0.98; n = 39 studies), but not with other growth factors. The IGFBP-3 -202A/C single nucleotide polymorphism was positively associated with prostate cancer (pooled OR for A/C vs. AA = 1.22; 95% CI 0.84, 1.79; OR for C/C vs. AA = 1.51; 1.03, 2.21, n = 8 studies). No strong associations were observed for IGF-II, IGFBP-1 or IGFBP-2 with either milk intake or prostate cancer risk. There was little consistency within the data extracted from the small number of animal studies. There was additional evidence to suggest that the suppression of IGF-II can reduce tumor size, and contradictory evidence with regards to the effect of IGFBP-3 suppression on tumor progression.

CONCLUSION

IGF-I is a potential mechanism underlying the observed associations between milk intake and prostate cancer risk.

Phase II Trial of Abiraterone Acetate Plus Prednisone in Black Men With Metastatic Prostate Cancer

Lessons Learned

The safety and activity findings of abiraterone acetate plus prednisone treatment in black men with mCRPC were similar to results from previously conducted studies with largely white populations.

Poor trial accrual continues to be a challenge in black men with mCRPC and further efforts are needed to address such underrepresentation.

Background.

Self-identified black men have higher incidence and mortality from prostate cancer in the United States compared with white men but are dramatically underrepresented in clinical trials exploring novel therapies for metastatic castration-resistant prostate cancer (mCRPC).

Methods.

Black men with mCRPC were treated with abiraterone acetate (AA), 1,000 mg daily, and prednisone (P), 5 mg twice daily. The primary objective was to determine antitumor activity (defined by a ≥30% decline in prostate-specific antigen [PSA] level) and to correlate germline polymorphisms in androgen metabolism genes with antitumor activity. Secondary objectives included determining safety, post-treatment changes in measurable disease, and time to disease progression.

Results.

From April 2013 to March 2016, a total of 11 black men were enrolled and received AA plus P (AA+P); 7 of 10 evaluable patients were docetaxel naive. Post-treatment declines in PSA level of ≥30% were achieved in 90% of patients. The side effect profile was consistent with prior clinical trials exploring AA+P in mCRPC. Due to poor accrual, the study was closed prematurely with insufficient sample size for the planned pharmacogenetic analyses.

Conclusion.

In this small prospective study terminated for poor accrual, the safety and activity of AA+P in black men with mCRPC was similar to that reported in prior studies exploring AA in largely white populations. Further efforts are needed to address underrepresentation of black men in mCRPC trials.

Assessing the role of insulin-like growth factors and binding proteins in prostate cancer using Mendelian randomization: Genetic variants as instruments for circulating levels

Circulating insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) are associated with prostate cancer. Using genetic variants as instruments for IGF peptides, we investigated whether these associations are likely to be causal. We identified from the literature 56 single nucleotide polymorphisms (SNPs) in the IGF axis previously associated with biomarker levels (8 from a genome-wide association study [GWAS] and 48 in reported candidate genes). In ∼700 men without prostate cancer and two replication cohorts (N ∼ 900 and ∼9,000), we examined the properties of these SNPS as instrumental variables (IVs) for IGF-I, IGF-II, IGFBP-2 and IGFBP-3. Those confirmed as strong IVs were tested for association with prostate cancer risk, low (< 7) vs. high (≥ 7) Gleason grade, localised vs. advanced stage, and mortality, in 22,936 controls and 22,992 cases. IV analysis was used in an attempt to estimate the causal effect of circulating IGF peptides on prostate cancer. Published SNPs in the IGFBP1/IGFBP3 gene region, particularly rs11977526, were strong instruments for IGF-II and IGFBP-3, less so for IGF-I. Rs11977526 was associated with high (vs. low) Gleason grade (OR per IGF-II/IGFBP-3 level-raising allele 1.05; 95% CI: 1.00, 1.10). Using rs11977526 as an IV we estimated the causal effect of a one SD increase in IGF-II (∼265 ng/mL) on risk of high vs. low grade disease as 1.14 (95% CI: 1.00, 1.31). Because of the potential for pleiotropy of the genetic instruments, these findings can only causally implicate the IGF pathway in general, not any one specific biomarker.

Polymorphisms of Estrogen Metabolism-Related Genes and Prostate Cancer Risk in Two Populations of African Ancestry

Background

Estrogens are thought to play a critical role in prostate carcinogenesis. It has been suggested that polymorphisms of genes encoding enzymes involved in estrogen metabolism are risk factors for prostate cancer. However, few studies have been performed on populations of African ancestry, which are known to have a high risk of prostate cancer.

Objective

We investigated whether functional polymorphisms of CYP17, CYP19, CYP1B1, COMT and UGT1A1 affected the risk of prostate cancer in two different populations of African ancestry.

Methods

In Guadeloupe (French West Indies), we compared 498 prostate cancer patients and 565 control subjects. In Kinshasa (Democratic Republic of Congo), 162 prostate cancer patients were compared with 144 controls. Gene polymorphisms were determined by the SNaPshot technique or short tandem repeat PCR analysis. Logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).

Results

The AA genotype and the A allele of rs4680 (COMT) appeared to be inversely associated with the risk of prostate cancer in adjusted models for both Afro-Caribbean and native African men. For the A allele, a significant inverse association was observed among cases with low-grade Gleason scores and localized clinical stage, in both populations.

Conclusions

These preliminary results support the hypothesis that polymorphisms of genes encoding enzymes involved in estrogen metabolism may modulate the risk of prostate cancer in populations of African ancestry.

Genetic polymorphisms in the androgen metabolism pathway and risk of prostate cancer in low incidence Malaysian ethnic groups

Androgens are involved in prostate cancer (PCa) cell growth. Genes involved in androgen metabolism mediate key steps in sex steroid metabolism. This study attempted to investigate whether single nucleotide polymorphisms (SNPs) in the androgen metabolism pathway are associated with PCa risk in low incidence Asian ethnic groups. We genotyped 172 Malaysian subjects for cytochrome P450 family 17 (CYP17A1), steroid-5-alpha-reductase, polypeptide 1 and 2 (SRD5A1 and SRD5A2), and insulin-like growth factor 1 (IGF-1) genes of the androgen metabolism pathway and assessed the testosterone, dihydrotestosterone and IGF-1 levels. SNPs in the CYP17A1, SRD5A1, SRD5A2, and IGF-1 genes were genotyped using real-time polymerase chain reaction. Although we did not find significant association between SNPs analysed in this study with PCa risk, we observed however, significant association between androgen levels and the IGF-1 and several SNPs. Men carrying the GG genotype for SNP rs1004467 (CYP17A1) had significantly elevated testosterone (P = 0.012) and dihydrotestosterone (DHT) levels (P = 0.024) as compared to carriers of the A allele. The rs518673 of the SRD5A1 was associated with prostate specific antigen (PSA) levels. Our findings suggest CYP17A1 rs1004467 SNP is associated with testosterone and DHT levels indicating the importance of this gene in influencing androgen levels in the circulatory system of PCa patients, hence could be used as a potential marker in PCa assessment.

IGFBP3 polymorphisms and risk of esophageal cancer in a Chinese population

Esophageal cancer is the sixth leading cause of cancer-related deaths worldwide. It is very aggressive with a poor prognosis. Besides environmental risk factors, genetic factors might contribute to the esophageal cancer carcinogenesis. To evaluate the association between the risk of esophageal squamous cell carcinoma (ESCC) and genetic variants in IGFBP3, we conducted a hospital-based case-control study to assess the genetic effects of these SNPs. A total of 380 esophageal squamous cell carcinoma (ESCC) cases and 380 controls were recruited for this study. The genotypes were determined using a matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The IGFBP3 single nucleotide polymorphisms (SNPs) rs2270628 C>T, rs10282088 C>A, and rs3110697 G>A were associated with a significantly decreased risk of ESCC. However, our results were obtained with a limited sample size. To confirm the current findings, larger studies with other ethnic populations are required.

Is there an association between variants in candidate insulin pathway genes IGF-I, IGFBP-3, INSR, and IRS2 and risk of colorectal cancer in the Iranian population?

BACKGROUND

Several epidemiological studies have shown associations between colorectal cancer (CRC) risk and type 2 diabetes and obesity. Any effects would be expected to be mediated through the insulin pathway. Therefore it is possible that variants of genes encoding components of the insulin pathway play roles in CRC susceptibility. In this study, we hypothesized that polymorphisms in the genes involving the insulin pathway are associated with risk of CRC.

MATERIALS AND METHODS

The associations of four single nucleotide polymorphisms (SNPs) in IGF-I (rs6214), IGFBP-3 (rs3110697), INSR (rs1052371), and IRS2 (rs2289046) genes with the risk of CRC were evaluated using a case-control design with 167 CRC cases and 277 controls by the PCR-RFLP method.

RESULTS

Overall, we observed no significant difference in genotype and allele frequencies between the cases and controls for the IGF-I, IGFBP-3, INSR, IRS2 gene variants and CRC before or after adjusting for confounders (age, BMI, sex, and smoking status). However, we observed that the IRS2 (rs2289046) GG genotype compared with AA+AG genotypes has a protective effect for CRC in normal weight subjects (p=0.035, OR=0.259, 95%CI= 0.074-0.907).

CONCLUSIONS

These findings do not support plausible associations between polymorphic variations in IGF-I, IGFBP-3, INSR, IRS2 genes and risk of CRC. However, the evidence for a link between the IRS2 (rs2289046) variant and risk of CRC dependent on the BMI of the subjects, requires confirmation in subsequent studies with greater sample size.

Genetic variation: effect on prostate cancer

The crucial role of androgens in the development of prostate cancer is well established. The aim of this review is to examine the role of constitutional (germline) and tumor-specific (somatic) polymorphisms within important regulatory genes of prostate cancer. These include genes encoding enzymes of the androgen biosynthetic pathway, the androgen receptor gene, genes that encode proteins of the signal transduction pathways that may have a role in disease progression and survival, and genes involved in prostate cancer angiogenesis. Characterization of deregulated pathways critical to cancer cell growth have lead to the development of new treatments, including the CYP17 inhibitor abiraterone and clinical trials using novel drugs that are ongoing or recently completed [1]. The pharmacogenetics of the drugs used to treat prostate cancer will also be addressed. This review will define how germline polymorphisms are known affect a multitude of pathways, and therefore phenotypes, in prostate cancer etiology, progression, and treatment.

Quantitative assessment of the association between CYP17 rs743572 polymorphism and prostate cancer risk

Published data on the association between CYP17 rs743572 polymorphism and risk of PC showed inconclusive results. The aim of this study was to further estimate the pooled effect size of rs743572 polymorphism and PC progression via large-scale meta-analysis. We searched the case-control studies of rs743572 polymorphism and PC risk in PubMed, Embase, and Web of Science databases up to February 2014. Odds ratios (ORs) along with 95 % confidence intervals (CIs) were pooled by means of both fixed effects model and random effects model. A total of 38 publications consisting of 42 studies with 15,735 cases and 17,825 controls were included in this meta-analysis. Overall, no significant association was found between rs743572 polymorphism and PC risk. Stratified analyses by control source and sample size did not provide significant results. However, there was a borderline association in African population under A2A2 versus A1A2 + A1A1 genetic model (OR = 1.39, 95 % CI: 1.01-1.92, P = 0.975, I (2) = 0.0 %). Results from the current meta-analysis suggested that CYP17 rs743572 polymorphism might modify the risk of PC in the subjects of African decent.

Association between the CYP3A4 and CYP3A5 polymorphisms and cancer risk: a meta-analysis and meta-regression

Previously published data on the association between CYP3A4 A392G and CYP3A5 Met235Thr polymorphisms and the risk of cancer remained controversial. Thus, we performed a meta-analysis to investigate the association between cancer susceptibility and CYP3A4 A392G (18,629 cases and 22,323 controls from 49 studies) and CYP3A5 Met235Thr polymorphisms (14,334 cases and 18,183 from 39 studies) in different inheritance models. We used odds ratios with 95 % confidence intervals to assess the strength of the association. Overall, significant association was found between CYP3A4 A392G polymorphism and cancer susceptibility (dominant model, odds ratio (OR) = 1.19; 95 % confidence interval (CI) = 1.03-1.38). In the further stratified and sensitivity analyses, significant increased prostate cancer risk was found among Caucasians (dominant model, OR = 1.88; 95 % CI = 1.20-2.95; recessive model, OR = 2.10; 95 % CI = 1.23-3.60; additive model, OR = 1.80, 95 % CI = 1.24-2.63; homozygous model, OR = 2.34, 95 % CI = 1.36-4.03; heterozygote model, OR = 1.79, 95 % CI = 1.11-2.89) for CYP3A4 A392G. For CYP3A5 Met235Thr polymorphism, no significant association was found among overall analysis and any subgroup analysis. In summary, this meta-analysis suggests that CYP3A4 A392G polymorphism is associated with increased prostate cancer risk among Caucasians and CYP3A5 Met235Thr polymorphism is not associated with the risk of cancer.

Global transcriptome analysis of formalin-fixed prostate cancer specimens identifies biomarkers of disease recurrence

Prostate cancer remains the second leading cause of cancer death in American men and there is an unmet need for biomarkers to identify patients with aggressive disease. In an effort to identify biomarkers of recurrence, we performed global RNA sequencing on 106 formalin-fixed, paraffin-embedded prostatectomy samples from 100 patients at three independent sites, defining a 24-gene signature panel. The 24 genes in this panel function in cell-cycle progression, angiogenesis, hypoxia, apoptosis, PI3K signaling, steroid metabolism, translation, chromatin modification, and transcription. Sixteen genes have been associated with cancer, with five specifically associated with prostate cancer (BTG2, IGFBP3, SIRT1, MXI1, and FDPS). Validation was performed on an independent publicly available dataset of 140 patients, where the new signature panel outperformed markers published previously in terms of predicting biochemical recurrence. Our work also identified differences in gene expression between Gleason pattern 4 + 3 and 3 + 4 tumors, including several genes involved in the epithelial-to-mesenchymal transition and developmental pathways. Overall, this study defines a novel biomarker panel that has the potential to improve the clinical management of prostate cancer.

Racial differences in the association of insulin-like growth factor pathway and colorectal adenoma risk

PURPOSE

Insulin resistance is believed to play an important role in the link between energy imbalance and colon carcinogenesis. Emerging evidence suggests that there are substantial racial differences in genetic and anthropometric influences on insulin-like growth factors (IGFs); however, few studies have examined racial differences in the associations of IGFs and colorectal adenoma, precursor lesions of colon cancer.

METHODS

We examined the association of circulating levels of IGF-1, IGFBP-3 and IGFBP-1, and SNPs in the IGF-1 receptor (IGF1R), IGF-2 receptor (IGF2R), and insulin receptor genes with risk of adenomas in a sample of 410 incident adenoma cases and 1,070 controls from the Case Transdisciplinary Research on Energetics and Cancer (TREC) Colon Adenomas Study.

RESULTS

Caucasians have higher IGF-1 levels compared to African Americans; mean IGF-1 levels are 119.0 ng/ml (SD = 40.7) and 109.8 ng/ml (SD = 40.8), respectively, among cases (p = 0.02). Mean IGF-1 levels are also higher in Caucasian controls (122.9 ng/ml, SD = 41.2) versus African American controls (106.9, SD = 41.2), p = 0.001. We observed similar differences in IGFBP3 levels by race. Logistic regression models revealed a statistically significant association of IGF-1 with colorectal adenoma in African Americans only, with adjusted odds ratios (ORs) of 1.68 (95 % CI 1.06-2.68) and 1.68 (95 % CI 1.05-2.71), respectively, for the second and third tertiles as compared to the first tertile. One SNP (rs496601) in IGF1R was associated with adenomas in Caucasians only; the per allele adjusted OR is 0.73 (95 % CI 0.57-0.93). Similarly, one IGF2R SNP (rs3777404) was statistically significant in Caucasians; adjusted per allele OR is 1.53 (95 % CI 1.10-2.14).

CONCLUSION

Our results suggest racial differences in the associations of IGF pathway biomarkers and inherited genetic variance in the IGF pathway with risk of adenomas that warrant further study.

The RTK/ERK pathway is associated with prostate cancer risk on the SNP level: a pooled analysis of 41 sets of data from case-control studies

Prostate cancer (PCa) is a malignant disease influencing numerous men worldwide every year. However, the exact pathogenesis and the genes, environment, and other factors involved have not been explained clearly. Some studies have proposed that cell signaling pathways might play a key role in the development and progression of PCa. According to our previous study, the RTK/ERK pathway containing nearly 40 genes was associated with PCa risk. On the basis of these genes, we conducted a meta-analysis with our own Chinese Consortium for Prostate Cancer Genetics (ChinaPCa) study and available studies in the databases to describe the association between the pathway and PCa on the SNP level. The results suggested that rs4764695/IGF1 (recessive model: pooled OR=0.92, 95%CI=0.852-0.994, P=0.034; I(2)=0%, P=0.042; allele analysis: pooled OR=0.915, 95%CI=0.874-0.958, P=0; I(2)=0%, P=0.424; codominant model: OR=0.835, 95%CI=0.762-0.916, P=0; I(2)=0%, P=0.684) and rs1570360/VEGF (recessive model: OR=0.596, 95%CI=0.421-0.843, P=0.003; I(2)=23.9%, P=0.269; codominant model: OR=0.576, 95%CI=0.404-0.820, P=0.002; I(2)=49.1%, P=0.140) were significantly associated with PCa. In subgroup analysis, the relationship was also found in Caucasians for IGF1 (dominant model: OR=0.834, 95%CI=0.769-0.904, P=0; allele analysis: OR=0.908, 95%CI=0.863-0.955, P=0; AA vs CC: OR=0.829, 95%CI=0.750-0.916, P=0; AC vs CC: OR=0.837, 95%CI=0.768-0.912, P=0). In addition, in Asians (allele analysis: OR=0.21, 95%CI=0.168-0.262, P=0) and Caucasians (recessive model: OR=0.453, 95%CI: 0.240-0.855, P=0.015; codominant model: OR=0.464, 95%CI=0.240-0.898, P=0.023) for VEGF, the association was significant. The results indicated that rs4764695/IGF1 and rs1570360/VEGF might play a key role in the development and progression of PCa. On the SNP level, we suggest that the study gives us a new view of gene-pathway analysis and targeted therapy for PCa.

Genetic and molecular differences in prostate carcinogenesis between African American and Caucasian American men

Prostate cancer is the most common non-skin cancer and the second leading cause of cancer-related death for men in the United States. Prostate cancer incidence and associated mortality are highest in African American men in comparison to other races. The observed differences in incidence and disease aggressiveness at presentation support a potential role for different pathways of prostate carcinogenesis between African American and Caucasian men. This review focuses on some of the recent molecular biology discoveries, which have been investigated in prostate carcinogenesis and their likely contribution to the known discrepancies across race and ethnicity. Key discussion points include the androgen receptor gene structure and function, genome-wide association studies and epigenetics. The new observations of the ethnic differences of the ERG oncogene, the most common prostate cancer gene, are providing new insights into ERG based stratification of prostate cancers in the context of ethnically diverse patient populations. This rapidly advancing knowledge has the likely potential to benefit clinical practice. Current and future work will improve the ability to sub-type prostate cancers by molecular alterations and lead to targeted therapy against this common malignancy.

Polymorphisms in CYP17 and CYP3A4 and prostate cancer in men of African descent

BACKGROUND

A meta and pooled analysis of published and unpublished case-control studies was performed to evaluate the association of CYP17 (rs743572) and CYP3A4 (rs2740574) polymorphisms and prostate cancer (PCa) in men from the USA, Caribbean, and Africa.

METHODS

Eight publications (seven studies) and two unpublished studies for CYP17 included 1,580 subjects (559 cases and 1,021 controls) and eleven publications and three unpublished studies for CYP3A4 included 3,400 subjects (1,429 cases and 1,971 controls).

RESULTS

Overall, the CYP17 heterozygous and homozygous variants were not associated with PCa, but they confer a 60% increased risk of PCa in a sub-group analysis restricted to African-American men (T/C + C/C, OR: 1.6, 95% CI: 1.1-2.4). No associations were observed for CYP3A4, overall and in stratified analyses for African-Americans and Africans. The pooled analysis suggests that after adjusting for study, age, PSA, and family history of PCa, CYP17 was associated with PCa for men of African ancestry (Adjusted OR: 3.5, 95% CI: 1.2-10.0).

CONCLUSIONS

Our findings suggest that genetic factors involved in the androgen pathway play a role in PCa risk among men of African ancestry.

Steroid 5-alpha-reductase type 2 (SRD5A2) V89L and A49T polymorphisms and sporadic prostate cancer risk: a meta-analysis

Steroid 5-α-reductase type 2 (SRD5A2) V89L and A49T polymorphisms are thought to play a crucial role in the androgen synthesis and metabolic pathway, but their associations with prostate cancer risk remain controversial. To provide a more precise estimation of the associations between V89L and A49T polymorphisms and prostate cancer risk, we performed a meta-analysis using all published case-control studies of prostate cancer since January 1995. We used odds ratio (OR) and its 95% confidence interval (CI) to assess the strength of the association under various genetic models in both overall and stratified analyses. We also calculated the false-positive report probability, the power of the current study, and the observed P value for significant findings. This analysis included 45 eligible studies of a total of 15,562 cases and 15,385 controls, in which no significant associations were found for the V89L polymorphisms under all genetic models. However, small excess prostate cancer risk was associated with the 49T allele in mixed populations compared with the 49A allele (OR = 1.24, 95% CI = 1.02-1.50), and similar results were observed in Caucasians (OR = 1.24, 95% CI = 1.01-1.53). The sensitivity analysis further strengthened the validity of these findings without publication bias. Although there was no overall association between V89L and prostate cancer risk, A49T might play a role in the etiology of prostate cancer among Caucasians. Additional large and well-designed studies are warranted to validate these findings.

A2 allele polymorphism of the CYP17 gene and prostate cancer risk in an iranian population

BACKGROUND

Studies have shown that alterations of steroid hormone metabolism, particularly involving testosterone, affect the risk of prostate cancer. Therefore, genetic variation in genes of enzymes which are involved could be of importance. The gene most interest is CYP17, whose enzyme product has an essential role in testosterone hormone synthesis. Some studies have indicated that the A2 allele polymorphism of CYP17 associated with increased risk of prostate cancer that could be affected by ethnicity. Therefore, the aim of this study was determination of presence or absence of the A2 allele in patients with prostate cancer.

MATERIALS AND METHODS

We studied the association of A2 allele and prostate cancer among 74 patients with prostate cancer and 128 healthy men which were referred to hospitals of SBMU.

RESULTS

This study revealed a significant association between prostate cancer risk and the A2 allele in an Iranian population so that A1A2 and A2A2 genotypes were more common in cases than controls with P-values of 0.029 and 0.010, respectively.

CONCLUSIONS

Results of our study support a possible role of the A2 allele in sporadic prostate cancer development in Iran, in line with findings elsewhere.

CYP17 T27C polymorphism and prostate cancer risk: a meta-analysis based on 31 studies

Objective

The cytochrome P450 17α-hydroxylase (CYP17) plays a vital role in androgen biosynthesis. A T-to-C polymorphism in the 5′ promoter region of CYP17 has been implicated as a risk factor for prostate cancer, but the results of individual studies are inconclusive or controversial. To derive a more precise estimation of the relationship, we performed an updated meta-analysis from 31 studies based on 27 publications.

Methods

A comprehensive search was conducted to examine all the eligible studies of CYP17 polymorphism and prostate cancer risk. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association.

Results

Overall, individuals with CC/CT genotype were not associated with prostate cancer risk (CC vs. TT: OR = 1.03, 95% CI = 0.86-1.24, P = 0.72, P_{heterogeneity} < 0.0001; CT vs. TT: OR = 0.99, 95% CI = 0.87-1.12, P = 0.88, P_{heterogeneity} = 0.0006). In the stratified analysis by ethnicity, there was a significantly increased risk of prostate cancer among individuals of African descent under the recessive model (OR = 1.56, 95% CI = 1.01-2.39, P = 0.04, P_{heterogeneity} = 0.65).

Conclusion

This meta-analysis suggested that CYP17 polymorphism might be associated with prostate cancer risk among individuals of African descent.

Ethnical disparities of prostate cancer predisposition: genetic polymorphisms in androgen-related genes

Prostate cancer (PCa) is the most commonly diagnosed male malignancy and the second biggest cause of cancer death in men of the Western world. Higher incidences of PCa occur in men from North America, Oceania and Western countries, whereas men from Asia and North Africa have a much lower PCa incidence rate. Investigations into this population disparity of PCa incidence, in order to identify potential preventive factors or targets for the therapeutic intervention of PCa, have found differences in both environmental and genetic variations between these populations. Environmental variations include both diet and lifestyle, which vary widely between populations. Evidence that diet comes into play has been shown by men who immigrate from Eastern to Western countries. PCa incidence in these men is higher than men in their native countries. However the number of immigrants developing PCa still doesn't match native black/white men, therefore genetic factors also contribute to PCa risk, which are supported by familial studies. There are a number of genetic polymorphisms that are differentially presented between Western and Eastern men, which are potentially associated with PCa incidence. Androgen and its receptor (AR) play a major role in PCa development and progression. In this study, we focus on genes involved in androgen biosynthesis and metabolism, as well as those associated with AR pathway, whose polymorphisms affect androgen level and biological or physiological functions of androgen. While many of the genetic polymorphisms in this androgen/AR system showed different frequencies between populations, contradictory evidences exist for most of these genes investigated individually as to the true contribution to PCa risk. More accurate measurements of androgen activity within the prostate are required and further studies need to include more African and Asian subjects. As many of these genetic polymorphisms may contribute to different steps in the same biological/physiological function of androgen and AR pathway, an integrated analysis considering the combined effect of all the genetic polymorphisms may be necessary to assess their contribution to PCa initiation and progression.

The impact of IGF-I gene polymorphisms on coronary artery disease susceptibility

BACKGROUND

Coronary artery disease (CAD) was the second leading cause of death for the past 3 years in Taiwan. The insulin-like growth factor (IGF) system is considered a new risk factor of CAD because investigations show that the levels and bioactivity of IGF-I and IGFBP-3 (where IGFBP is insulin-like growth factor-binding protein) may be involved in elevating the risk of CAD. This study investigated the relationships among IGF-I +1770, IGF-I +6093, and IGFBP-3 -202 genetic polymorphisms and CAD in the Taiwanese population.

METHODS

A total of 581 subjects, including 390 non-CAD controls and 191 patients with CAD, were recruited and the isolated DNA was subjected to real-time polymerase chain to evaluate the effects of these three polymorphic variants on CAD.

RESULTS

Our results showed a significant association between the IGF-I +1770 gene polymorphism and increased risk of CAD. Furthermore, CAD patients with a minimum of one mutant C allele, T/C or C/C, in IGF-I +1770 gene polymorphism had significantly high blood pressure including systolic blood pressure (SBP; P = 0.025) and diastolic blood pressure (DBP; P = 0.004), compared to CAD patients with T/T homozygotes. Moreover, CAD patients with a minimum of one mutant A allele, G/A or A/A, in the IGF-I +6093 gene polymorphism had a 1.695-fold elevated risk of congestive heart failure (CHF), compared to CAD patients with the G/G homozygote.

CONCLUSIONS

Polymorphism of IGF-I +1770 was associated with increased CAD risk. In CAD patients, the contributions of IGF-I +1770 and +6093 could be through the effect on blood pressure in CAD patients.

Polymorphisms in androgen signaling pathway predisposing to prostate cancer

Prostate cancer is the most frequent male malignancy diagnosed in western countries and androgens are known to mediate key physiological processes in prostate tissue. Since endogenous androgens have long been considered to be risk factors for prostate cancer, genes involved in androgen biosynthesis and metabolism have been extensively studied. In this review, association of androgen pathway genes, their polymorphic sites and risk of prostate cancer in different ethnic backgrounds is addressed together with their use to predict susceptibility and clinical outcomes of prostate cancer patients. The effect of the polymorphisms seems vary in different patients, populations and ethnic backgrounds. To date it is evident that the association between androgen pathway gene polymorphisms and prostate cancer risk is complex and many of the results are characterized by irreproducibility, which can be attributed to a variety of biological, statistical and technical reasons. In the future, with increasing knowledge, developing technologies and new genomic biomarkers it likely becomes possible to better estimate the risk of prostate cancer, and distinguish indolent disease from aggressive based on molecular profiling, and the analysis of gene-gene and gene-environment interactions.

A false single nucleotide polymorphism generated by gene duplication compromises meat traceability

Controlling meat traceability using SNPs is an effective method of ensuring food safety. We have analyzed several SNPs to create a panel for bovine genetic identification and traceability studies. One of these was the transversion g.329C>T (Genbank accession no. AJ496781) on the cytochrome P450 17A1 gene, which has been included in previously published panels. Using minisequencing reactions, we have tested 701 samples belonging to eight Spanish cattle breeds. Surprisingly, an excess of heterozygotes was detected, implying an extreme departure from Hardy-Weinberg equilibrium (P<0.001). By alignment analysis and sequencing, we detected that the g.329C>T SNP is a false positive polymorphism, which allows us to explain the inflated heterozygotic value. We recommend that this ambiguous SNP, as well as other polymorphisms located in this region, should not be used in identification, traceability or disease association studies. Annotation of these false SNPs should improve association studies and avoid misinterpretations.

CYP17 gene polymorphisms and prostate cancer risk: a meta-analysis based on 38 independent studies

BACKGROUND

The results of recent published studies focusing on CYP17 polymorphisms in prostate cancer (PCa) susceptibility are often conflicting. We performed a meta-analysis based on 38 independent studies to evaluate the association.

METHODS

Data were collected from the following electronic databases: PubMed, Excerpta Medica Database, and Chinese Biomedical Literature Database, with the last report up to September 2010. Meta-analysis was conducted in a fixed/random effect model.

RESULTS

Thirty-eight independent studies including 34,782 cases and 38,626 controls on the association of CYP17 gene polymorphisms with PCa risk in different ethnic groups were identified. The meta-analysis was performed for five polymorphisms: rs743572 (A1/A2, 38 studies), rs6162 (C/T, 3 studies), rs619824 (C/A, 4 studies), rs2486758 (T/C, 4 studies), and rs10883782 (A/G, 4 studies). When all groups were pooled, we did not detect the association of rs743572 polymorphism with PCa risk. In the subgroup analysis, a significant association of rs743572 polymorphism and PCa was found in Black population (A2/A2 vs. A1/A1 + A2/A1: OR = 1.70, 95% CI = 1.08-2.69, P = 0.02), but not in Caucasian or Asian population. For other polymorphisms, we found that rs619824 polymorphism was associated with a significant decreased risk of PCa (A vs. C: OR = 0.95, 95% CI = 0.92-0.99, P = 0.01), and rs2486758 polymorphism was associated with a significant increased risk of PCa (C vs. T: OR = 1.07, 95% CI = 1.03-1.12, P = 0.002).

CONCLUSION

This meta-analysis suggests that rs743572 polymorphism is associated with PCa risk in Black population, but not in Caucasian or Asian population. Moreover, our study suggests that rs619824 and rs2486758 polymorphisms are associated with PCa risk.

Disparities at presentation, diagnosis, treatment, and survival in African American men, affected by prostate cancer

BACKGROUND

Prostate cancer (PCa) remains the most common malignancy and the second leading cause of cancer death among men in the United States. PCa exhibits the most striking racial disparity, as African American men are at 1.4 times higher risk of being diagnosed, and 2-3 times higher risk of dying of PCa, compared to Caucasian men. The etiology of the disparity has not been clearly elucidated. The objective of this article is to critically review the literature and summarize the most prominent PCa racial disparities accompanied by proposed explanations.

METHODS

The present literature on disparities at presentation, diagnosis, treatment, and survival of African American men affected by PCa was systematically reviewed. Original research as well as relevant review articles were included.

RESULTS

African American men persistently present with more advanced disease than Caucasian men, are administered different treatment regimens than Caucasian men, and have shorter progression-free survival following treatment. In addition, African American men report more treatment-related side-effects that translates to the diminished quality of life (QOL).

CONCLUSIONS

PCa racial disparity exists at stages of presentation, diagnosis, treatment regimens, and subsequent survival, and the QOL. The disparities are complex involving biological, socio-economic, and socio-cultural determinants. These mounting results highlight an urgent need for future clinical, scientific, and socio-cultural research involving transdisciplinary teams to elucidate the causes for PCa racial disparities.

Mechanisms of prostate cancer initiation and progression

Prostate cancer is a major health problem as it continues to be the most frequently diagnosed cancer in men in the Western world. While improved early detection significantly decreased mortality, prostate cancer still remains the second leading cause of cancer-related death in Western men. Understanding the mechanisms of prostate cancer initiation and progression should have a significant impact on development of novel therapeutic approaches that can help to combat this disease. The recent explosion of novel high-throughput genetic technologies together with studies in animal models and human tissues allowed a comprehensive analysis and functional validation of the molecular changes. This chapter will summarize and discuss recently identified critical genetic and epigenetic changes that drive prostate cancer initiation and progression. These discoveries should help concentrate the efforts of drug development on key pathways and molecules, and finally translate the knowledge that is gained from mechanistic studies into effective treatments.

CYP17 gene polymorphism and prostate cancer susceptibility in a Tunisian population

Prostate cancer (PCa) formation has been reported to be associated with androgen. Two key steps in the sex steroid synthesis are mediated by the enzyme cytochrome P450c 17α which is encoded in the CYP17 gene. The A2 allele of the CYP17 gene has been thought to be associated with increased functional activity of this steroidogenic enzyme. Consequently, the A2 allele has been examined as a biomarker of individual susceptibility to hormone-related diseases among men. We prospectively assessed the association between the A2 allele of CYP17 and PCa risk among 125 cases and 125 controls in a case-control study. Our aim was to investigate whether a polymorphism of CYP17 gene could be used as a genetic marker for associating PCa. The result revealed a significant association between the CYP17 polymorphic genotypes and PCa. Therefore, CYP17 gene polymorphism is likely contributed to the pathogenesis of PCa but not to disease severity.

Meta-analysis of three polymorphisms in the steroid-5-alpha-reductase, alpha polypeptide 2 gene (SRD5A2) and risk of prostate cancer

The steroid-5-alpha-reductase, alpha polypeptide 2 (SRD5A2) gene plays a crucial role in androgen metabolism pathway in human prostate. It encodes SRD5A2 enzyme, which catalyses testosterone to dihydrotestosterone (DHT). DHT is the main active structure binding with androgen receptor (AR). After the activation of AR, it further regulates a series of target genes in androgen metabolism pathway. However, no clear consensus has been reached on the association between the SRD5A2 V89L, A49T and TA repeat polymorphisms and prostate cancer (PCa) risk. Thus, we performed a meta-analysis of 31 association studies with 14,726 PCa cases and 15,802 controls. We found no association between PCa and 89L compared with 89V allele [odds ratio (OR) = 1.02, 95% confidence interval (CI) 0.98-1.06, P(heterogeneity) = 0.44]. The 49T allele showed a significantly elevated effect on the high stage (Stages III-IV) of PCa risk both under the dominant genetic model (OR = 2.13, 95% CI 1.44-3.15, P(heterogeneity) = 0.65) and in the contrast T versus A allele (OR = 2.06, 95% CI 1.41-3.02, P(heterogeneity) = 0.69). There was a significantly decreased association between PCa and long TA repeat as compared versus short TA repeat (OR = 0.86, 95% CI 0.74-1.00, P(heterogeneity) = 0.79). No significant between-study heterogeneity was found in all subjects under four genetic models (dominant model, recessive model, allele comparison and homozygosity comparison) for these three polymorphisms, respectively, so the fixed effects model was used to pool the result. Our result indicated that carriers of 49T might improve the risk of PCa in higher stages (Stages III-IV), carriers of long TA repeat might decrease the risk of PCa and 89L may not be an important risk factor for PCa. However, due to the limited sample sizes, this meta-analysis did not achieve sufficiently conclusive results. Still more well-designed studies should be performed to clarify the role of these three polymorphisms in the development of PCa.

Evaluation of the influence of polymorphic variants CYP1A1 2B, CYP1B1 2, CYP3A4 1B, GSTM1 0, and GSTT1 0 in prostate cancer

BACKGROUND/OBJECTIVE

Genetic polymorphisms in cytochrome P-450 (CYPs) and glutathione S-transferase (GSTs) genes can influence the appearance of tumors by the formation of new enzymes with altered activities. In the present study, 5 polymorphic variants were examined in 154 patients with prostate carcinoma and in 154 controls.

MATERIALS AND METHODS

DNA analysis was carried out through PCR-based methods. The statistical methods used were odds ratio and confidence interval (95% CI), χ(2), Fisher, and Mann-Whitney.

RESULTS

The study showed absence of association for CYP1A1 2B, CYP1B1 2, GSTM1 0, and GSTT1 0. The statistical analysis implied a positive association of variant CYP3A4 1B for prostate cancer. The combined analysis of CYP1A1 2B, CYP1B1 2, and CYP3A4 1B genotypes showed positive association. The analysis of histopathologic parameters detected statistically significant differences for Gleason score and biochemistry recurrence risk. The presence of the GSTT1 0 genotype in red meat consumers increased the risk for this disease.

CONCLUSION

Some polymorphic variants analyzed can influence the development and the progression of prostate cancer.

Association of body mass index with prostate cancer biochemical failure

PURPOSE

The association between obesity and biochemical failure measured by prostate specific antigen after prostate cancer treatment is controversial. We determined whether there is an association between body mass index and biochemical failure in men treated for low and intermediate risk prostate cancer with various treatment modalities.

MATERIALS AND METHODS

We performed a cohort study in 2,687 patients who underwent treatment for low and intermediate risk prostate adenocarcinoma as described by National Comprehensive Cancer Network guidelines at Cleveland Clinic between January 1996 and December 2005. Univariate and multivariate analyses were done to determine the effect of multiple patient characteristics on biochemical failure.

RESULTS

There were 319 biochemical failures (11.9%). Body mass index as a continuous variable was significantly associated with biochemical failure on univariate analysis (HR 1.030, p = 0.02). There was a significant association with biochemical failure when comparing normal vs overweight and normal vs obese men but not overweight vs obese men. On multivariate analysis body mass index as a continuous or a categorical variable was not significantly associated with biochemical failure. Multivariate analysis revealed certain variables significantly associated with biochemical failure, including black race, greater initial prostate specific antigen, Gleason score 7, treatment type and more frequent prostate specific antigen screening.

CONCLUSIONS

We found a significant association between body mass index and biochemical failure on univariate analysis that did not hold true on multivariate analysis. Black race was associated with biochemical failure on multivariate analysis. The reason for this is unclear. Future studies should further characterize the relationship between race and biochemical failure.

Review of studies on metabolic genes and cancer in populations of African descent

Genetic polymorphisms described for a number of enzymes involved in the metabolism of tobacco carcinogens and alcohol have been linked to increase cancer risk. Racial disparities in cancer between whites and populations of African descent are well documented. In addition to differences in access to health care, both environment and genetic factors and their interaction may contribute to the increased cancer risk in minority populations. We reviewed the literature to identify case-control studies that included subjects of African descent. Meta-analyses investigating the association of genetic polymorphisms in tobacco metabolic genes and cancer were performed. Although several genes and cancers have been studied, only one or two studies per gene for each cancer site have been published, with the exception of breast (CYP1A1 and CYP1B1), lung (GSTM1, CYP1A1, and NQO1), and prostate (CYP3A4 A293G and CYP17). Marginal statistically significant associations were observed for CYP3A4 A293G and CYP17 5'UTR polymorphisms and prostate cancer. Our findings support the need for additional genetic association studies of breast, prostate, and lung cancers that include a larger number of minority participants. Because incidence and mortality rates for these cancers rank highest among populations of African descent, concentrated research in these areas are warranted.

SRD5A2 V89L polymorphism and prostate cancer risk: a meta-analysis

BACKGROUND

Increasing studies investigating the association between steroid 5-alpha reductase type II gene polymorphism at codon 89 (SRD5A2 V89L) and susceptibility to prostate cancer (PCa) confer inconsistent results. To precisely estimate the relationship with more statistical power, a meta-analysis was performed.

METHODS

A comprehensive search was conducted to identify all case-control studies investigating such an association. Odds ratio (OR) and its 95% confidence interval (CI) were used to evaluate the size effect.

RESULTS

Twenty-five eligible reports were identified including 8,615 cases/9,089 controls in 33 comparisons. In overall analysis, no significant associations were found in all genetic models. Subgroup analyses by ethnicity revealed that small excess PCa risks were observed in dominant model (OR, 1.11; 95% CI, 1.03-1.19 for (LL + VL) vs. VV; P < 0.01; P(heterogeneity) = 0.49) and L allele frequency comparison (OR, 1.09; 1.03-1.15 for L allele frequency; P < 0.01; P(heterogeneity) = 0.07) in Europeans. Meanwhile, SRD5A2 V89L polymorphism was significantly associated with an increased PCa risk in men aged < or =65 under the co-dominant (OR, 1.70; 95% CI, 1.09-2.66 for LL vs. VV; P = 0.02; P(heterogeneity) = 0.31) and recessive (OR, 1.75; 95% CI, 1.14-2.68 for LL vs. (VV + VL); P = 0.01; P(heterogeneity) = 0.12) models. However, no significant associations were found in Asians and Africans.

CONCLUSIONS

Our study suggests SRD5A2 V89L polymorphism could play a low-penetrant role in PCa risk among Europeans and individuals younger than 65 years. Additional well-designed studies are warranted to validate these findings.

Genetic variation in CYP17A1 and pancreatic cancer in a population-based case-control study in the San Francisco Bay Area, California

Pancreatic cancer is the fourth leading cause of cancer-related death in men and women in the United States. Reproductive factors and steroid hormones have been suspected risk factors for many years, but the results from epidemiologic studies to date have been inconclusive. CYP17A1 encodes cytochrome P450c17alpha, an enzyme with 17alpha-hydroxylase and 17,20-lyase activities in estradiol biosynthesis. A polymorphism in the 5'UTR promoter region of CYP17A1-34T/C(A1/A2) has been associated with circulating estrogens in premenopausal women and with susceptibility to breast, prostate, and endometrial cancer. Questionnaire data and germline DNA collected in a San Francisco Bay Area population-based case-control study of pancreatic cancer (cases = 532, controls = 1701) were used to conduct analyses of pancreatic cancer susceptibility related to the CYP17A1 polymorphism and whether effects associated with smoking and reproductive risk factors were modified by this polymorphism. Mass spectrometry- and TaqMan-based methods were used to determine CYP17A1 genotypes in DNA samples from 308 cases and 964 controls. Results showed that carriers of the A2 allele (vs. A1/A1) were significantly less likely to have been diagnosed with pancreatic cancer (A1/A2, adjusted odds ratio (OR) = 0.77, 95% confidence interval (CI) = 0.58-1.0; A2/A2, OR = 0.63, 95%CI = 0.42-0.93; p-trend = 0.01). ORs for CYP17A1 genotypes did not differ by sex, but the observed inverse association was stronger in postmenopausal women. ORs for smoking and pancreatic cancer were not modified by CYP17A1 genotype. Our results suggest that the CYP17A1 A2 allele may be associated with a lower risk of pancreatic cancer in both men and women.

Current affairs in quantitative targeted proteomics: multiple reaction monitoring-mass spectrometry

Quantitative targeted proteomics has recently taken front stage in the proteomics community. Centered on multiple reaction monitoring-mass spectrometry (MRM-MS) methodologies, quantitative targeted proteomics is being used in the verification of global proteomics data, the discovery of lower abundance proteins, protein post-translational modifications, discrimination of select highly homologous protein isoforms and as the final step in biomarker discovery. An older methodology utilized with small molecule analysis, the proteomics community is making great technological strides to develop MRM-MS as the next method to address previously challenging issues in global proteomics experimentation, namely dynamic range, identification of post-translational modifications, sensitivity and selectivity of measurement which will undoubtedly further biomedical knowledge. This brief review will provide a general introduction of MRM-MS and highlight its novel application for targeted quantitative proteomic experimentations.

Association among polymorphisms in the steroid 5alpha-reductase type II (SRD5A2) gene, prostate cancer risk, and pathologic characteristics of prostate tumors in an Ecuadorian population

Androgens are essential to normal prostate growth and development. It is therefore possible that polymorphisms in the androgen synthesis gene 5alpha-reductase type II (SRD5A2) may be involved in the progression of prostate tumors. We evaluated the relationship of two single-nucleotide polymorphisms, A49T and V89L, with prostate cancer risk in a case-control study. A total of 114 prostate cancer patients and 144 healthy control males were genotyped. We found highly significant differences between the two polymorphisms, the risk of developing prostate cancer, and some of the clinical-pathologic characteristics. Individuals who carry at least one V allele may have a higher risk of developing prostate cancer [odds ratio (OR) = 7.5, 95% confidence interval (CI) = 2.57-22.08, P<0.001]. In addition, individuals with LL genotype showed reduction in the progression to a higher tumor stage (OR = 0.10, 95%CI = 0.040-0.27, P<0.001). The A49T substitution was associated with a higher pTNM stage (OR = 2.87, 95%CI 1.14-7.21, P = 0.003) and elevated Gleason grade (OR = 3.14, 95%CI = 1.12-8.78; P = 0.004). Furthermore, the allelic frequencies of the A49T variant (33% controls and 45% cases) are the highest reported worldwide. These findings suggest that among the Ecuadorian population, these polymorphisms influence the risk of developing prostate cancer.

The SRD5A2 V89L polymorphism is associated with severity of disease in men with early onset prostate cancer

BACKGROUND

Emerging evidence indicates that testosterone (T), and not dihydrotestosterone (DHT), is the most relevant androgen that promotes carcinogenesis in the prostate. Steroid 5-alpha reductase type II (SRD5A2) catalyzes the irreversible conversion of T to DHT in male reproductive organs. Because the SRD5A2 gene is highly polymorphic at codon 89, two SRD5A2 isoforms are expressed that differ in K(m) and V(max) values. The more common and rapid catalytic isoform contains a valine residue at position 89; the slower-catalytic variant contains leucine at this position.

METHODS

Thirty-three men with early onset prostate cancer (PCa) were genotyped for the SRD5A2 V89L substitution and other polymorphisms in genes encoding receptors or enzymes that play important roles in pathways of steroid metabolism to ascertain if they were associated with standard clinical measures of disease progression at the time of diagnosis.

RESULTS

The expression of at least one SRD5A2 leucine allele in young men with PCa was associated with more significant disease at the time of presentation, as was defined by pretreatment PSA level, clinical staging and Gleason score when compared with affected subjects harboring the more common SRD5A2 valine variant. A dosage effect of a single leucine allele was evident in heterozygotes, as values of their clinical and pathological variables were consistently situated between the extremes of the homozygous V or L phenotypes.

CONCLUSION

The SRD5A2 leucine isoform appears to be acting in a dose-dependent manner as a significant disease-modifying factor in young men diagnosed with PCa.

Substantial family history of prostate cancer in black men recruited for prostate cancer screening: results from the Prostate Cancer Risk Assessment Program

BACKGROUND

Black men are at increased risk for prostate cancer (PCA), particularly with a family history (FH) of the disease. Previous reports have raised concern for suboptimal screening of black men with an FH of PCA. The extent of FH of PCA are reported from a prospective, longitudinal PCA screening program for high-risk men.

METHODS

Black men ages 35 to 69 years are eligible for PCA screening through the Prostate Cancer Risk Assessment Program (PRAP) regardless of FH. Rates of self-reported FH of PCA, breast, and colon cancer at baseline were compared with an age-matched sample of black men from the 2005 National Health Interview Survey (NHIS) using standard statistical methods.

RESULTS

As of January 2007, 332 black men with pedigree information were enrolled in PRAP and FH of PCA was compared with 838 black men from the 2005 NHIS. Black men in PRAP reported significantly more first-degree relatives with PCA compared with black men in the 2005 NHIS (34.3% [95% confidence interval (95% CI), 29.2-39.7] vs 5.7% [95% CI, 3.9-7.4]). Black men in PRAP also had more FH of breast cancer compared with those in the 2005 NHIS (11.5% [95% CI, 8.2-15.4] vs 6.3% [95% CI, 4.6-8.0]).

CONCLUSIONS

FH of PCA appears to be a motivating factor for black men seeking PCA screening. Targeted recruitment and education among black families should improve PCA screening rates. Efforts to recruit black men without an FH of PCA are also needed.

Androgens and the molecular epidemiology of prostate cancer

PURPOSE OF REVIEW

Despite clinical and experimental evidence that show androgens are important in prostate carcinogenesis, epidemiologic studies of serum androgens have been inconclusive. In this review, we summarize the current state of the literature and provide insights and direction for epidemiologic research on androgens and prostate cancer.

RECENT FINDINGS

To date, data on serum androgens in prostate cancer remain inconclusive. Large studies on variants in some androgen-metabolizing genes [SRD5A2, CYP17A1, and hydroxysteroid dehydrogenase (HSD)17B1] do not show a convincing links to prostate cancer, though there are insufficient data to draw conclusions on other genes related to androgen metabolism, including UDP-glycosyltransferases (UGT), sulfotransferases (SULT), CYP3A, and estrogen-related genes. There is some evidence, although controversial, suggesting that select variants may confer risk to certain subtypes of prostate cancer. The most notable finding in 2007 is the highly reproducible link between the chromosome 8q24 risk region and prostate cancer susceptibility.

SUMMARY

Besides the link between the 8q24 region and prostate cancer risk, population studies do not convincingly show that polymorphisms in androgen metabolism genes are associated with prostate cancer risk. Large epidemiologic studies with comprehensive gene coverage and reliable exposure data are needed to clarify further the role of androgens and their related genes in prostate cancer.