Purpose: Aberrant DNA methylation changes are common somatic alterations in prostate carcinogenesis. We examined the methylation status of six genes in prostate tissue specimens from African American (AA) and Caucasian (Cau) males.Experimental Design: We used pyrosequencing to quantitatively measure the methylation status of GSTP1, AR, RARβ2, SPARC, TIMP3, and NKX2-5. Real-time PCR was used to determine gene expression, and gene reactivation was analyzed by 5-aza-2′-deoxycytidine and/or trichostatin A treatment.Results: Statistical analysis showed significantly higher methylation in the prostate cancer tissue samples in comparison with matched normal samples for GSTP1 (P = 0.0001 for AA; P = 0.0008 for Cau), RARβ2 (P < 0.001 for AA and Cau), SPARC (P < 0.0001 for AA and Cau), TIMP3 (P < 0.0001 for AA and Cau), and NKX2-5 (P < 0.0001 for AA; P = 0.003 for Cau). Overall, we observed significant differences (P < 0.05) in the methylation level for all genes, except GSTP1, in the AA samples in comparison with the Cau samples. Furthermore, regression analysis revealed significantly higher methylation for NKX2-5 (P = 0.008) and TIMP3 (P = 0.039) in normal prostate tissue samples from AA in comparison with Cau, and a statistically significant association of methylation with age for NKX2-5 (P = 0.03) after adjusting for race.Conclusion: Our findings show higher methylation of several genes in prostate

Increasing evidence suggests that aberrant DNA methylation changes may contribute to prostate cancer (PCa) ethnic disparity. To comprehensively identify DNA methylation alterations in PCa disparity, we used the Illumina 450K methylation platform to interrogate the methylation status of 485,577 CpG sites focusing on gene-associated regions of the human genome. Genomic DNA from African-American (AA; 7 normal and 3 cancers) and Caucasian (Cau; 8 normal and 3 cancers) was used in the analysis. Hierarchical clustering analysis identified probe-sets unique to AA and Cau samples, as well as common to both. We selected 25 promoter-associated novel CpG sites most differentially methylated by race (fold change > 1.5-fold; adjusted P < 0.05) and compared the b-value of these sites provided by the Illumina, Inc. array with quantitative methylation obtained by pyrosequencing in 7 prostate cell lines. We found very good concordance of the methylation levels between b-value and pyrosequencing. Gene expression analysis using qRT-PCR in a subset of 8 genes after treatment with 5-aza-2 0 -deoxycytidine and/or trichostatin showed up-regulation of gene expression in PCa cells. Quantitative analysis of 4 genes, SNRPN, SHANK2, MST1R, and ABCG5, in matched normal and PCa tissues derived from AA and Cau PCa patients demonstrated differential promoter methylation and concomitant differences in mRNA expression in prostate tissues from AA vs. Cau. Regression analysis in normal and PCa tissues as a function of race showed significantly higher methylation prevalence for SNRPN (P D 0.012), MST1R (P D 0.038), and ABCG5 (P < 0.0002) for AA vs. Cau samples. We selected the ABCG5 and SNRPN genes and verified their biological functions by Western blot analysis and siRNA gene knockout effects on cell proliferation and invasion in 4 PCa cell lines (2 AA and 2 Cau patients-derived lines). Knockdown of either ABCG5 or SNRPN resulted in a significant decrease in both invasion and proliferation in Cau PCa cell lines but we did not observe these remarkable loss-offunction effects in AA PCa cell lines. Our study demonstrates how differential genome-wide DNA methylation levels influence gene expression and biological functions in AA and Cau PCa.

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BACKGROUND p53 is a transcription factor that regulates the cell cycle, DNA repair, and apoptosis. A variant at codon 72, rs1042522, results in altered activities for p53 and is, notably, differentially distributed among different ethnic populations. However, associations of this variant with cancer in men of African descent have not been explored. Herein, we tested the hypothesis that rs1042522 was associated with prostate cancer (PCa) risk. MATERIALS AND METHODS Genotypes were determined by PCR-RFLP methods in a study population of African descent consisting of 266 PCa patients and 196 male controls. RESULTS Our results indicate that the p53 polymorphism may be associated with increased risk of PCa. Genotypes were significantly and marginally associated with PCa risk using the dominant and log-additive genetic models (OR = 1.53, 95% CI: 1.02–2.29, P = 0.04; OR = 1.33, 95% CI: 0.99–1.78, P = 0.06, respectively). After adjusting for age, the associations with PCa remained, but results were not statistically significant (OR = 1.48, 95% CI: 0.95–2.31, P = 0.08; OR = 1.30, 95% CI: 0.95–1.80, P = 0.10, respectively). CONCLUSIONS The present study demonstrates that population-dependent differences in allele frequencies associated with health disparities provide a valuable framework for the interrogation of complex diseases in all populations.

Sickle erythrocytes have increased ferritin and increased molecular iron on the inner membrane leaflet, and we postulated that cytosolic labile iron is also elevated. We used the fluorescent metallosensor, calcein, and a permeant Fe 2؉ chelator to estimate labile cytoslic Fe 2؉ , and calcein plus an Fe 3؉ chelator to estimate total cytosolic labile iron (Fe 2؉ ؉ Fe 3؉ ). We measured membrane nonheme iron by its reactivity with ferrozine. As estimated by calcein and Fe 2؉ chelator, the mean ؎ SD labile Fe 2؉ concentration was significantly lower in hemoglobin (Hb) SS (n ‫؍‬ 29) than hemoglobin AA (n ‫؍‬ 17) erythrocytes (0.56 ؎ 0.35 M versus 1.25 ؎ 0.65 M; P < .001). In contrast, as estimated by calcein and Fe 3؉ chelator, total erythrocyte labile iron was similar in hemoglobin SS (n ‫؍‬ 12) and hemoglobin AA (n ‫؍‬ 10) participants (1.75 ؎ 0.41 M versus 2.14 ؎ 0.93 M; P ‫؍‬ .2). Mean membrane nonheme iron levels were higher in hemoglobin SS cells than hemoglobin AA cells (0.0016 ؋ 10 ؊4 versus 0.0004 ؋ 10 ؊4 fmol/cell; P ‫؍‬ .01), but much lower than the mean amounts of total labile iron (1.6-1.8 ؋ 10 ؊4 fmol/ cell) or hemoglobin iron (18 000-19 000 ؋ 10 ؊4 fmol/cell

BACKGROUND-African American men have the highest rates of prostate cancer worldwide, and immunogenetic studies suggest that people of African descent have increased susceptibility to diseases of inflammation. Since genetic susceptibility is an etiological factor in prostate cancer, we hypothesize that sequence variants in the promoter region of the CD14 gene that regulate inflammation may modify individual susceptibility to this disease.

BACKGROUND Prostate cancer (PCa) is a common malignancy and a leading cause of cancer death among men in the United States with African-American (AA) men having the highest incidence and mortality rates. Given recent results from admixture mapping and genome-wide association studies for PCa in AA men, it is clear that many risk alleles are enriched in men with West African genetic ancestry. METHODS A total of 77 ancestry informative markers (AIMs) within surrounding candidate gene regions were genotyped and haplotyped using Pyrosequencing in 358 unrelated men enrolled in a PCa genetic association study at the Howard University Hospital between 2000 and 2004. Sequence analysis of promoter region single-nucleotide polymorphisms (SNPs) to evaluate disruption of transcription factor-binding sites was conducted using in silico methods. RESULTS Eight AIMs were significantly associated with PCa risk after adjusting for age and West African ancestry. SNP rs1993973 (intervening sequences) had the strongest association with PCa using the log-additive genetic model (P = 0.002). SNPs rs1561131 (genotypic, P = 0.007), rs1963562 (dominant, P = 0.01) and rs615382 (recessive, P = 0.009) remained highly significant after adjusting for both age and ancestry. We also tested the independent effect of each significantly associated SNP and rs1561131 (P = 0.04) and rs1963562 (P = 0.04) remained significantly associated with PCa development. After multiple comparisons testing using the false discovery rate, rs1993973 remained significant. Analysis of the rs156113–, rs1963562–rs615382l and rs1993973–rs585224 haplotypes revealed that the least frequently found haplotypes in this population were significantly associated with a decreased risk of PCa (P = 0.032 and 0.0017, respectively). CONCLUSIONS The approach for SNP selection utilized herein showed that AIMs may not only leverage increased linkage disequilibrium in populations to identify risk and protective alleles, but may also be informative in dissecting the biology of PCa and other health disparities.

Association studies for complex diseases based on haplotype data have received increasing attention in the last few years. A commonly used nonparametric method, which takes haplotype structure into consideration, is to use the U-statistic to compare the similarities between genetic compositions in the case and control populations. Although the method and its variants are convenient to use in practice, there are some areas where the tests cannot detect even large differences between cases and controls. To overcome this problem and enhance the power, we propose a new form of the weighted U-statistic, which directly compares the dissimilarity between the haplotype structures in the case and control populations. We show that this test statistic is asymptotically a linear combination of the absolute values of normal random variables under the null hypothesis, and shifts strictly toward the right under the alternative, and therefore has no blind areas of detection. Simulation studies indicate that our test statistic overcomes the weakness of the existing ones and is robust and powerful as well.