Identification of genetic risk associated with prostate cancer using ancestry informative markers.

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.

p53 Pro72Arg polymorphism and prostate cancer in men of African descent.

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.

Association of GNB3 C825T polymorphism with peak oxygen consumption.

The C825T single nucleotide polymorphism (SNP) in the guanine nucleotide-binding protein, beta polypeptide 3 ( GNB3) gene gives rise to a splice variant, GNB3s that has enhanced G protein activation and signal transduction activity. This variant has been reported to be associated with cardiovascular disease, diabetes and obesity. We studied this SNP in 95 healthy 18 to 30 year-old African American university students to determine its association with aerobic capacity and cardiorespiratory fitness as measured by peak oxygen consumption (VO (2)peak). We also tested the effect of heart rate variability (HRV) as an independent predictor of VO (2)peak. We tested the association of the SNP and HRV with VO (2)peak in a multivariate regression analysis with appropriate adjustments of covariates, under dominant and recessive models. We found a significant independent association of the 825T allele with VO (2)peak under the dominant model (beta-coef.=-0.101, P=0.0442). We also observed that HRV marginally influenced VO (2)peak. This finding suggests that GNB3 C825T polymorphism is associated with VO (2)peak which is influenced by autonomic modulation of heart rate in African Americans.

A common nonsense mutation in EphB2 is associated with prostate cancer risk in African American men with a positive family history.

BACKGROUND: The EphB2 gene was recently implicated as a prostate cancer (PC) tumour suppressor gene, with somatic inactivating mutations occurring in approximately 10% of sporadic tumours. We evaluated the contribution of EphB2 to inherited PC susceptibility in African Americans (AA) by screening the gene for germline polymorphisms. METHODS: Direct sequencing of the coding region of EphB2 was performed on 72 probands from the African American Hereditary Prostate Cancer Study (AAHPC). A case-control association analysis was then carried out using the AAHPC probands and an additional 183 cases of sporadic PC compared with 329 healthy AA male controls. In addition, we performed an ancestry adjusted association study where we adjusted for individual ancestry among all subjects, in order to rule out a spurious association due to population stratification. RESULTS: Ten coding sequence variants were identified, including the K1019X (3055A-->T) nonsense mutation which was present in 15.3% of the AAHPC probands but only 1.7% of 231 European American (EA) control samples. We observed that the 3055A-->T mutation significantly increased risk for prostate cancer over twofold (Fisher's two sided test, p = 0.003). The T allele was significantly more common among AAHPC probands (15.3%) than among healthy AA male controls (5.2%) (odds ratio 3.31; 95% confidence interval 1.5 to 7.4; p = 0.008). The ancestry adjusted analyses confirmed the association. CONCLUSIONS: Our data show that the K1019X mutation in the EphB2 gene differs in frequency between AA and EA, is associated with increased risk for PC in AA men with a positive family history, and may be an important genetic risk factor for prostate cancer in AA.

Clinical characteristics of African-American men with hereditary prostate cancer: the AAHPC Study.

INTRODUCTION: The African-American Hereditary Prostate Cancer (AAHPC) Study was designed to recruit African-American families fulfilling very stringent criteria of four or more members diagnosed with prostate cancer at a combined age at diagnosis of 65 years or less. This report describes the clinical characteristics of a sample of affected AAHPC family members. METHODS: In all, 92 African-American families were recruited into the study between 1998 and 2002. Complete clinical data including age and PSA at diagnosis, number of affected per family, stage, grade, and primary treatment were available on 154 affected males. Nonparametric Wilcoxon two-sample tests and Fisher's exact test (two-tailed), were performed to compare families with 4-6 and >6 affected males with respect to clinical characteristics. RESULTS: The mean number of affected men per family was 5.5, with a mean age at diagnosis of 61.0 (+/-8.4) years. Age at diagnosis, PSA and Gleason score did not show significant differences between the two groups of families. Based on the Gleason score, 77.2% of affected males had favorable histology. Significantly, there were marked differences between the two groups in the frequency of node-positive disease (P=0.01) and distant metastases (P=0.0001). Radical prostatectomy was the preferred primary therapy for 66.2% of all affected men followed by 20.8% who chose radiation therapy. CONCLUSIONS: Our findings suggest that affected males who carry the highest load of genetic factors are at the highest risk for early dissemination of disease, thus efforts at early diagnosis and aggressive therapeutic approaches may be warranted in these families. Since the primary therapy choices in our study favored definitive treatment (87.0%) when compared to the 1983 and 1995 SEER data in which 28 and 64% received definitive treatment, respectively, it appears that affected African-American men in multiplex families may be demonstrating the reported psycho-social impact of family history on screening practices and treatment decisions for prostate cancer.

Extent of linkage disequilibrium between the androgen receptor gene CAG and GGC repeats in human populations: implications for prostate cancer risk.

While studies have implicated alleles at the CAG and GGC trinucleotide repeats of the androgen receptor gene with high-grade, aggressive prostate cancer disease, little is known about the normal range of variation for these two loci, which are separated by about 1.1 kb. More importantly, few data exist on the extent of linkage disequilibrium (LD) between the two loci in different human populations. Here we present data on CAG and GGC allelic variation and LD in six diverse populations. Alleles at the CAG and GGC repeat loci of the androgen receptor were typed in over 1000 chromosomes from Africa, Asia, and North America. Levels of linkage disequilibrium between the two loci were compared between populations. Haplotype variation and diversity were estimated for each population. Our results reveal that populations of African descent possess significantly shorter alleles for the two loci than non-African populations (P<0.0001). Allelic diversity for both markers was higher among African Americans than any other population, including indigenous Africans from Sierra Leone and Nigeria. Analysis of molecular variance revealed that approx. 20% of CAG and GGC repeat variance could be attributed to differences between the populations. All non-African populations possessed the same common haplotype while the three populations of African descent possessed three divergent common haplotypes. Significant LD was observed in our sample of healthy African Americans. The LD observed in the African American population may be due to several reasons; recent migration of African Americans from diverse rural communities following urbanization, recurrent gene flow from diverse West African populations, and admixture with European Americans. This study represents the largest genotyping effort to be performed on the two androgen receptor trinucleotide repeat loci in diverse human populations.

Cyp17 promoter variant associated with prostate cancer aggressiveness in African Americans.

Androgens play an important role in the etiology of prostate cancer. The CYP17 gene encodes the cytochrome P450c17alpha enzyme, which is the rate-limiting enzyme in androgen biosynthesis. A T to C polymorphism in the 5' promoter region has recently been associated with prostate cancer. However, contradictory data exists concerning the risk allele. To investigate further the involvement of the CYP17 variant with prostate cancer, we typed the polymorphism in three different populations and evaluated its association with prostate cancer and clinical presentation in African Americans. We genotyped the CYP17 polymorphism in Nigerian (n = 56), European-American (n = 74), and African-American (n = 111) healthy male volunteers, along with African-American men affected with prostate cancer (n = 71), using pyrosequencing. Genotype and allele frequencies did not differ significantly across the different control populations. African-American men with the CC CYP17 genotype had an increased risk of prostate cancer (odds ratio, 2.8; 95% confidence interval, 1.0-7.4) compared with those with the TT genotype. A similar trend was observed between the homozygous variant genotype in African-American prostate cancer patients and clinical presentation. The CC genotype was significantly associated with higher grade and stage of prostate cancer (odds ratio, 7.1; 95% confidence interval, 1.4-36.1). The risk did not differ significantly by family history or age. Our results suggest that the C allele of the CYP17 polymorphism is significantly associated with increased prostate cancer risk and clinically advanced disease in African Americans.

African-American heredity prostate cancer study: a model for genetic research.

A genome-wide scan of high-risk prostate cancer families in North America has demonstrated linkage of a particular marker to Chromosome 1q (HPC1). An even greater proportion of African-American families have shown linkage to HPC1. Therefore, investigators at the National Human Genome Research Institute (NHGRI) in collaboration with Howard University and a predominantly African-American group of urologists established the African-American Hereditary Prostate Cancer (AAHPC) Study Network to confirm the suggested linkage of HPC in African Americans with a gene on Chromosome 1. Blood samples from recruited families were sent to Howard University for extraction of DNA. The DNA was sent to NHGRI at NIH where the genotyping and genetic sequence analysis was conducted. Genotype data are merged with pedigree information so that statistical analysis can be performed to establish potential linkage. From March 1, 1998, to June 1, 1999, a total of 40 African-American families have been recruited who met the study criteria. Preliminary results suggest that racial/ethnicity grouping may affect the incidence and extent of linkage of prostate cancer to specific loci. The importance of these findings lays in the future treatment of genetic-based diseases.

African-American heredity prostate cancer study: a model for genetic research.

A genome-wide scan of high-risk prostate cancer families in North America has demonstrated linkage of a particular marker to Chromosome Iq (HPC11. An even greater proportion of African-American families have shown linkage to HPC 1. Therefore, investigators at the National Human Genome Research Institute [NHGRI] in collaboration with Howard University and a predominantly African-American group of urologists established the African-American Hereditary Prostate Cancer (AAHPC) Study Network to confirm the suggested linkage of HPC in African Americans with a gene on Chromosome 1. Blood samples from recruited families were sent to Howard University for extraction of DNA. The DNA was sent to NHGRI at NIH where the genotyping and genetic sequence analysis was conducted. Genotype data are merged with pedigree information so that statistical analysis can be performed to establish potential linkage. From March 1, 1998, to June 1, 1999, a total of 40 African-American families have been recruited who met the study criteria. Preliminary results suggest that racial/ethnicity grouping may affect the incidence and extent of linkage of prostate cancer to specific loci. The importance of these findings lays in the future treatment of genetic-based diseases.

Recruitment experience in the first phase of the African American Hereditary Prostate Cancer (AAHPC) study.

The African American Hereditary Prostate Cancer (AAHPC) Study is an ongoing multicenter genetic linkage study organized by Howard University and the National Human Genome Research Institute (NHGRI), with support from the Office for Research on Minority Health and the National Cancer Institute. The goals of the study are to: (i) look for evidence of involvement of chromosome 1q24-25 (HPC1) in African American men with hereditary prostate cancer (HPC) and (ii) conduct a genome-wide search for other loci associated with HPC in African American men. To accomplish these goals, a network has been established including Howard University, the NHGRI, and six Collaborative Recruitment Centers (CRCs). The CRCs are responsible for the identification and enrollment of 100 African American families. To date, 43 families have been enrolled. Recruitment strategies have included mass media campaigns, physician referrals, community health-fairs/prostate cancer screenings, support groups, tumor registries, as well as visits to churches, barber shops, and universities. By far, the most productive recruitment mechanisms have been physician referrals and tumor registries, yielding a total of 35 (81%) families. Approximately 41% (n = 3400) of probands initially contacted by phone or mail expressed interest in participating; the families of 2% of these met the eligibility criteria, and 75% of those families have been enrolled in the study, indicating a 0.5% recruitment yield (ratio of participants to contacts). As the first large-scale genetic linkage study of African Americans, on a common disease, the challenges and successes of the recruitment process for the AAHPC Study should serve to inform future efforts to involve this population in similar studies.

BRCA1 mutations in African Americans.

The breast cancer predisposing gene, BRCA1, was analyzed for germline mutations in 45 African American families at high-risk for hereditary breast cancer. Patients were considered high-risk if they had a family history of the disease, early onset breast cancer, bilateral breast cancer, or breast and ovarian cancer. The entire BRCA1 coding and flanking intron regions have been examined by single stranded conformation polymorphism analysis followed by sequencing of variant bands. Eleven different BRCA1 germline mutations/variations were identified in 7 patients from the 45 high-risk families. Two pathogenic, protein-truncating mutations were detected in exon 11. A ten base pair tandem duplication, 943ins10, was present in a woman with breast and ovarian cancer whose first-degree relatives had prostate cancer. A four base pair deletion, 3450del4, was detected in a breast cancer patient with five cases of breast cancer in the family; two of the proband's sisters with breast cancer also carried the same mutation. Four amino acid substitutions (Lys1183Arg, Leu1564Pro, Gln1785His, and Glu1794Asp) and four nucleotide substitutions in intron 22 (IVS22+78 C/A, IVS22+67 T/C, IVS22+8 T/A and IVS22+7 T/C) were observed in patients and not in control subjects. One early onset breast cancer patient carried five distinct BRCA1 variations, two amino acid substitutions and three substitutions in intron 22. An amino acid substitution in exon 11, Ser1140Gly, was identified in 3 different unrelated patients and in 6 of 92 control samples. The latter probably represents a benign polymorphism.

Plasma lipid alterations in African-American women with breast cancer.

The purpose of this study was to examine the relationship between plasma lipid and lipoprotein levels, stage of disease and breast cancer risk in African-American women. The study population comprised 163 African-American women: patients (n = 58) and controls (n = 105), with mean ages of 57.2 years and 47.7 years respectively. Approximately 71% and 56% of the women with breast cancer and the control population, respectively, were postmenopausal. Those with cancer had significantly higher education levels, P < or = 0.01, and higher triglyceride levels compared to the controls, P < or = 0.001, but lower body mass index (BMI) levels, P < or = 0.01. There were no statistically significant differences observed in total cholesterol, high-density-lipoprotein-containing cholesterol and low-density-lipoprotein-containing cholesterol between the patients and controls. After adjustments for age, education, BMI, and menopausal status, triglycerides remained significantly and positively associated with breast cancer risk. The significant correlation between the high levels of triglycerides and breast cancer risk (odds ratio = 5.12) may be attributed to differences in lipid metabolism between the women with breast cancer and controls, or to the consequences of breast cancer.

Serum antibodies to HIV-1 are produced post-measles virus infection: evidence for cross-reactivity with HLA.

Convalescent sera obtained from patients who were recently recovered from an acute measles virus infection were tested for the presence of anti-HIV-1 antibodies by Western blot analysis. While 16% (17/104) of control sera displayed reactive bands to a variety of HIV proteins, 62% (45/73) of convalescent sera demonstrated immunoreactive bands corresponding to HIV-1 Pol and Gag, but not Env antigens. This cross-reactivity appears to be the result of an active measles infection. No HIV-1 immunoblot reactivity (0/10) was observed in sera obtained from young adults several weeks after a combined measles, mumps, and rubella (MMR) vaccination. Interestingly, examination of anti-HLA typing sera specific for either class I and class II molecules revealed that 46% (19/41) of these sera contained cross-reactive antibodies to HIV-1 proteins. Absorption of measles sera with mixed lymphocyte reaction (MLR)-activated lymphocytes and/or HIV-1 recombinant proteins significantly decreased or removed the presence of these HIV-1-immunoreactive antibodies. Together, these findings suggest that the immune response to a natural measles virus infection results in the production of antibodies to HIV-1 and possibly autoantigens.

The relationship of body mass index to reproductive factors in pre- and postmenopausal African-American women with and without breast cancer.

To date, there are virtually no existing data on the relationship between obesity, menopausal status, and breast cancer in African-Americans. Therefore, the present study was designed to test the following hypotheses in an African-American population: (1) there exists a positive association between BMI and breast cancer among postmenopausal women; (2) there exists an inverse association between BMI and breast cancer among premenopausal women; and (3) similar associations between BMI and reproductive factors exist for both pre- and postmenopausal breast cancer cases. The study population comprised 357 African-American women (n = 193 breast cancer cases; n = 164 controls). No significant differences were observed between premenopausal cases and controls for BMI, obesity categories, and reproductive factors. Among the postmenopausal women, the cases had significantly lower weight and BMI levels than the controls. Age at first pregnancy and parity were significantly lower among postmenopausal cases than their controls. No significant associations were revealed between body mass index and breast cancer for pre- and postmenopausal women. In the present study, early age at menarche was the only reproductive factor that was an independent predictor of BMI for both pre- and postmenopausal women, irrespective of breast cancer status. Also, these findings strongly suggest the need to consider reproductive factors, particularly age at menarche, as a covariate of BMI and other obesity-related diseases.

HLA and multiple myeloma among black and white men: evidence of a genetic association.

To evaluate the possibility that genetic factors contribute to the excess rates of multiple myeloma among blacks, serological typing of human leukocyte antigens (HLA) was conducted for black and white male patients and controls who participated in a large population-based case-control interview study. Forty-six black cases, 88 black controls, 85 white cases, and 122 white controls were typed for the Class I antigens (HLA-A, -B, -C) and for the Class II antigens (HLA-DR, HLA-DQ). Black cases had significantly higher gene frequencies than black controls for Bw65, Cw2, and DRw14, while white cases had higher gene frequencies than white controls for A3 and Cw2 and blanks at the DR and DQ loci. Further analysis of the association between Cw2 and multiple myeloma revealed relative risks of 5.7 (95% confidence interval = 1.5-26.6) and 2.6 (95% confidence interval = 1.0-7.2) for blacks and whites, respectively. The frequency of Cw2 in black and white controls was similar. These findings suggest that the Cw2 allele enhances the risk of myeloma in blacks and whites but do not explain the higher incidence of this cancer among blacks. The study also suggests that undefined DQ antigens may play an etiological role, supporting the need for further research into the immunogenetic determinants of myeloma.

Inhibition of growth of subcutaneous xenografts and metastasis of human breast carcinoma by swainsonine: modulation of tumor cell HLA class I antigens and host immune effector mechanisms.

Swainsonine, an indolizidine alkaloid, can decrease the organ colonization potential of metastatic murine tumor cells by augmentation of host immune effector mechanisms. In this report the above findings were extended by the demonstration that systemic administration of swainsonine strongly suppressed the growth of human breast carcinoma subcutaneous xenografts and experimentally induced lung metastases. This inhibition was not due to a direct effect of swainsonine on cell growth. However swainsonine treatment of tumor cells resulted in enhanced expression of HLA Class I antigens, and HLA class I mRNA. Swainsonine was a potent immunodulator as evidenced by the increased (a) cytotoxicity of splenocytes and macrophages, and, (b) proliferative potential of splenocytes and bone marrow cells. These data suggest that swainsonine-induced inhibition of tumor growth and metastases may be mediated via activation of host effector cells and/or alteration of tumor cell antigenicity.

Cryopreservation of human lymphocyte function as measured by in vitro assays.

Methods are described by which cryopreserved cells can be utilized in a number of in vitro assays. On a per cell basis, nearly total recovery of function can be demonstrated for lymphocyte transformation (mitogens, antigens and MLC) and rosette-forming cells. Excellent recovery of mononuclear cell production of leukocyte migration inhibitory factor was also observed. Highly reproducible activity was recovered on a per lymphocyte basis in lymphocyte cytotoxicity but with a definite decrement in the percentage recovery. Both for longitudinal studies of immune function and for standardization of these assays in one or more laboratories such cryopreserved cells are ofimmense value and should be widely utilized.