Faculty Bibliography

Selection and genetic drift can create genetic differences between populations. Cytokines and chemokines play an important role in both hematopoietic development and the inflammatory response. We compared the genotype frequencies of 45 SNPs in 30 cytokine and chemokine genes in two healthy Chinese populations and one Caucasian population. Several SNPs in IL4 had substantial genetic differentiation between the Chinese and Caucasian populations (F ST approximately 0.40), and displayed a strikingly different haplotype distribution. To further characterize common genetic variation in worldwide populations at the IL4 locus, we genotyped 9 SNPs at the IL4 gene in the Human Diversity Panel's (N = 1056) individuals from 52 world geographic regions. We observed low haplotype diversity, yet strikingly different haplotype frequencies between non-African populations, which may indicate different selective pressures on the IL4 gene in different parts of the world. SNPs in CSF2, IL6, IL10, CTLA4, and CX3CR1 showed moderate genetic differentiation between the Chinese and Caucasian populations (0.15 < F ST < 0.25). These results suggest that there is substantial genetic diversity in immune genes and exploration of SNP associations with immune-related diseases that vary in incidence across these two populations may be warranted

BACKGROUND: Alpha-methylacyl-CoA racemase (AMACR), which prepares branched chain fatty acids to be metabolized for energy and is implicated in the activation of the COX-inhibiting form of ibuprofen, is overexpressed in prostate cancer and its precursor lesions. Significant differences in AMACR allele frequencies have been reported for hereditary prostate cancer (HPC), but the relevance of AMACR in the context of its substrates have not been studied. METHODS: We conducted a nested case-control study of 1,318 prostate cancer cases and 1,842 controls from the screening arm of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Five non-synonymous (nsSNP) and two intronic AMACR polymorphisms were genotyped. Conditional logistic regression models were used to evaluate the associations between the genetic variants and prostate cancer. RESULTS: Overall, prostate cancer was not related to AMACR gene variants; however, risks for prostate cancer were significantly reduced among regular ibuprofen users who carried allele variants at four nsSNP loci (M9V, D175G, S201L, and K277E; all P(trend) < 0.05) or carried the TGTGCG haplotype (OR = 0.65; 95% CI 0.44-0.97). No AMACR-related associations were noted among nonregular ibuprofen users (all P(interaction) > 0.33). CONCLUSION: AMACR gene variants were unrelated to prostate cancer overall in this study. The protective associations observed among ibuprofen users suggest that AMACR gene variants may enhance the chemopreventive effects of ibuprofen on prostate cancer risk

BACKGROUND: Estrogen receptor beta (ESR2) may play a role in modulating prostate carcinogenesis through the regulation of genes related to cell proliferation and apoptosis. METHODS: We conducted nested case-control studies in the Breast and Prostate Cancer Cohort Consortium (BPC3) that pooled 8,323 prostate cancer cases and 9,412 controls from seven cohorts. Whites were the predominant ethnic group. We characterized genetic variation in ESR2 by resequencing exons in 190 breast and prostate cancer cases and genotyping a dense set of single nucleotide polymorphisms (SNP) spanning the locus in a multiethnic panel of 349 cancer-free subjects. We selected four haplotype-tagging SNPs (htSNP) to capture common ESR2 variation in Whites; these htSNPs were then genotyped in all cohorts. Conditional logistic regression models were used to assess the association between sequence variants of ESR2 and the risk of prostate cancer. We also investigated the effect modification by age, body mass index, and family history, as well as the association between sequence variants of ESR2 and advanced-stage (>or=T3b, N1, or M1) and high-grade (Gleason sum >or=8) prostate cancer, respectively. RESULTS: The four tag SNPs in ESR2 were not significantly associated with prostate cancer risk, individually. The global test for the influence of any haplotype on the risk of prostate cancer was not significant (P = 0.31). However, we observed that men carrying two copies of one of the variant haplotypes (TACC) had a 1.46-fold increased risk of prostate cancer (99% confidence interval, 1.06-2.01) compared with men carrying zero copies of this variant haplotype. No SNPs or haplotypes were associated with advanced stage or high grade of prostate cancer. CONCLUSION: In our analysis focused on genetic variation common in Whites, we observed little evidence for any substantial association of inherited variation in ESR2 with risk of prostate cancer. A nominally significant (P < 0.01) association between the TACC haplotype and prostate cancer risk under the recessive model could be a chance finding and, in any event, would seem to contribute only slightly to the overall burden of prostate cancer

Transforming growth factor beta 1 (TGFB1) is a multifunctional cytokine that has been implicated in the pathogenesis of colorectal neoplasia. To investigate the association between genetic variants in TGFB1 and the risk of colorectal adenoma, we conducted a case-control study of 754 advanced adenoma cases and 769 controls from the baseline screening exam of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Cases included participants diagnosed with advanced left-sided adenoma (>or=1 cm, high-grade dysplasia or villous characteristics), and controls were subjects without evidence of a left-sided polyp by sigmoidoscopy. DNA was extracted from blood specimens, and five single-nucleotide polymorphisms in TGFB1 of known or suggested functional significance (-800G>A, -509C>T, Leu10Pro, Arg25Pro and Thr263Ile) were genotyped. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association between each polymorphism and adenoma. The high TGFB1 producer genotypes, -509TT and 10Pro/Pro, were associated with an increased risk of colorectal adenoma compared with other genotypes (OR = 1.51, 95% CI: 1.04-2.20 and OR = 1.37, 95% CI: 1.02-1.86, respectively). These increased risks, particularly for -509TT, were greater for persons with multiple adenomas (OR = 1.89, 95% CI: 1.16-3.09, P = 0.01) and individuals with rectal adenoma (OR = 2.95, 95% CI: 1.66-5.26, P = 0.0002). Haplotype analysis revealed similar findings under a recessive model. No associations were observed for polymorphisms at codons 25 and 263. In conclusion, variants that enhance TGFB1 production may be associated with an increased risk of advanced colorectal adenoma

A recent analysis showed that the excess odds ratio (EOR) for lung cancer due to smoking can be modeled by a function which is linear in total pack-years and exponential in the logarithm of smoking intensity and its square. Below 15-20 cigarettes per day, the EOR/pack-year increased with intensity (direct exposure rate or enhanced potency effect), suggesting greater risk for a total exposure delivered at higher intensity (for a shorter duration) than for an equivalent exposure delivered at lower intensity. Above 20 cigarettes per day, the EOR/pack-year decreased with increasing intensity (inverse exposure rate or reduced potency effect), suggesting greater risk for a total exposure delivered at lower intensity (for a longer duration) than for an equivalent exposure delivered at higher intensity. The authors applied this model to data from 10 case-control studies of cancer, including cancers of the lung, bladder, oral cavity, pancreas, and esophagus. At lower intensities, there was enhanced potency for several cancer sites, but narrow ranges for pack-years increased uncertainty, precluding definitive conclusions. At higher intensities, there was a consistent reduced potency effect across studies. The intensity effects were statistically homogeneous, indicating that after accounting for risk from total pack-years, intensity patterns were comparable across the diverse cancer sites

BACKGROUND: Several epidemiologic studies have reported associations between fruit and vegetable intake and reduced risk of prostate cancer, but the findings are inconsistent and data on clinically relevant advanced prostate cancer are limited. METHODS: We evaluated the association between prostate cancer risk and intake of fruits and vegetables in 1338 patients with prostate cancer among 29,361 men (average follow-up = 4.2 years) in the screening arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Participants completed both a general risk factor and a 137-item food-frequency questionnaire at baseline. Cox proportional hazards models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs). All statistical tests were two-sided. RESULTS: Vegetable and fruit consumption was not related to prostate cancer risk overall; however, risk of extraprostatic prostate cancer (stage III or IV tumors) decreased with increasing vegetable intake (RR = 0.41, 95% CI = 0.22 to 0.74, for high versus low intake; P(trend) = .01). This association was mainly explained by intake of cruciferous vegetables (RR = 0.60, 95% CI = 0.36 to 0.98, for high versus low intake; P(trend) = .02), in particular, broccoli (RR = 0.55, 95% CI = 0.34 to 0.89, for >1 serving per week versus <1 serving per month; P(trend) = .02) and cauliflower (RR = 0.48, 95% CI = 0.25 to 0.89 for >1 serving per week versus <1 serving per month; P(trend) = .03). We found some evidence that risk of aggressive prostate cancer decreased with increasing spinach consumption, but the findings were not consistently statistically significant when restricted to extraprostatic disease. CONCLUSION: High intake of cruciferous vegetables, including broccoli and cauliflower, may be associated with reduced risk of aggressive prostate cancer, particularly extraprostatic disease

BACKGROUND: alpha-Methylacyl-CoA racemase (AMACR), an enzyme involved in oxidation of branched chain fatty acids and cholesterol metabolites, as well as ibuprofen metabolism, is overexpressed in colorectal adenomas and cancer. AMACR gene variants have been associated with hereditary prostate cancer, but no studies have evaluated their etiologic role in colorectal carcinogenesis. METHODS: We conducted a case-control study of 725 advanced distal colorectal adenoma cases and 729 frequency-matched controls from the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Seven AMACR polymorphisms were genotyped. Unconditional logistic regression models were used to evaluate the associations adjusting for age at randomization and gender. RESULTS: The 201L allele of S201L [TT versus CC: odds ratio (OR), 1.74; 95% confidence interval (95% CI), 1.15-2.62; TC versus CC: OR, 1.17; 95% CI, 0.93-1.49] and the 277E allele of K277E (GG versus AA: OR, 1.66; 95% CI, 1.03-2.68; GA versus AA: OR, 1.21; 95% CI, 0.96-1.53) were associated with increased risk of advanced distal colorectal adenoma (both P(trend) </= 0.02); the TGTGCG haplotype of six informative single nucleotide polymorphisms was also associated with increased risk (OR, 1.27; 95% CI, 1.03-1.55). Regular ibuprofen users who were homozygous for the variant allele at either M9V or D175G were at reduced risk for adenoma (both P(interaction) < 0.05). CONCLUSION: Our study identified variants in AMACR associated with advanced distal colorectal adenoma and pointed to potential interactions with ibuprofen use

Superoxide dismutase (SOD) plays a key role in the detoxification of superoxide free radicals. We evaluated the association of prostate cancer with genetic polymorphisms in SOD1 (CuZn-SOD; IVS3-251A>G), SOD2 [MnSOD; Ex2+24T>C (V16A)], and SOD3 (EC-SOD; IVS1+186C>T, Ex3-631C>G, Ex3-516C>T, and Ex3-489C>T), the three main isoforms of SOD. Prostate cancer cases (n = 1,320) from the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial were frequency matched to nondiseased controls (n = 1,842) by age, race, time since initial screening, and year of blood draw. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI); stratified analysis by the level of antioxidative vitamins was also conducted. The higher activity Ala variant at SOD2 Ex2+24T>C (V16A), which has been hypothesized to suppress prostate carcinogenesis, was associated with elevation of prostate cancer risk in Caucasians (Val/Ala versus Val/Val: OR, 1.17; 95% CI, 0.97-1.42; Ala/Ala versus Val/Val: OR, 1.28; 95% CI, 1.03-1.60; P(trend) = 0.03). Stratification by quartiles of dietary and supplemental vitamin E intake (IU/d) showed risks of prostate cancer tended to be increased among SOD2 Ala allele carriers, except at the highest quartile of vitamin E intake (>222; P(interaction) = 0.06, Q1-Q3 versus Q4). The association between Ala allele and prostate cancer risk among those with lower intake of vitamin E (</=222) was stronger for smokers (OR, 1.44; 95% CI, 1.10-1.90). No significant association with prostate cancer was observed for polymorphic variants in SOD3 or SOD1. These results suggest that the Ala variant of SOD2 is associated with moderately increased risk of prostate cancer, particularly among men with lower intakes of dietary and supplemental vitamin E

Catechol-O-methyltransferase (COMT) is an important modulator in the catabolism of extraneural dopamine, which plays an important role in drug reward mechanisms. It is hypothesized that genetic variations in the COMT gene, which can result in a three to fourfold difference in COMT enzyme activity, may be associated with several reward-motivated behaviors. The aim of our study was to examine the relationship between COMT polymorphisms with smoking, obesity and alcohol. Three single nucleotide polymorphisms (SNPs) in COMT were genotyped in 2,371 participants selected randomly from the screening arm of the PLCO Cancer Screening Trial after stratifying by sex, age, and smoking status. Smoking, obesity, and alcohol consumption were assessed by questionnaire. SNP and haplotype associations were estimated using odds ratios (ORs) and 95% confidence intervals (CIs) derived from conditional logistic regression models, adjusted for race/ethnicity. The COMT Ex4-76C > G (Leu136Leu) polymorphism was statistically significantly associated with individuals who had >30% increases in BMI from ages 20 to 50 years, compared to those with 0-5% increase in BMI (0-5%) over the same age period: (CC is referent; OR(CG )= 1.42, OR(GG )= 1.46, P (trend )= 0.06). By sex, the increased risk was further pronounced among females (OR(CG )= 1.50, OR(GG )= 2.10, P (trend )= 0.03). Consistent with our analyses of single polymorphisms, individuals whose BMI increased >30% from ages 20 to 50 years were more likely than individuals with 0-5% increases in BMI to possess COMT haplotypes [COMT Ex3-104C > T-COMT Ex4-76 C > G-COMT Ex4-12 A > G] that included the variant allele for COMT Ex4-76 C > G: C-G-G (T-C-A is referent: OR(C-G-G )= 1.33, 95% CI 1.01-1.77) and C-G-A (OR(C-G-A )= 1.79, 95% CI 0.72-4.49). We observed no association between any of the COMT polymorphisms with smoking behavior or alcohol intake. The COMT Ex4-76C > G (Leu136Leu) polymorphism appears to play a role in large increases in BMI. The null association with smoking and alcohol and the pronounced association with increasing BMI among women further implicates COMT's role in estrogen metabolism as a potentially culpable pathway. Our results support a need for comprehensive evaluation of COMT variations and their functional relevance as COMT may be an important molecular target to evaluate for new treatments regarding obesity