Identification of a Functional Genetic Variant at 16q12.1 for Breast Cancer Risk: Results from the Asia Breast Cancer Consortium

Genetic factors play an important role in the etiology of breast cancer. We carried out a multi-stage genome-wide association (GWA) study in over 28,000 cases and controls recruited from 12 studies conducted in Asian and European American women to identify genetic susceptibility loci for breast cancer. After analyzing 684,457 SNPs in 2,073 cases and 2,084 controls in Chinese women, we evaluated 53 SNPs for fast-track replication in an independent set of 4,425 cases and 1,915 controls of Chinese origin. Four replicated SNPs were further investigated in an independent set of 6,173 cases and 6,340 controls from seven other studies conducted in Asian women. SNP rs4784227 was consistently associated with breast cancer risk across all studies with adjusted odds ratios (95% confidence intervals) of 1.25 (1.20−1.31) per allele (P = 3.2×10−25) in the pooled analysis of samples from all Asian samples. This SNP was also associated with breast cancer risk among European Americans (per allele OR  = 1.19, 95% CI  = 1.09−1.31, P = 1.3×10−4, 2,797 cases and 2,662 controls). SNP rs4784227 is located at 16q12.1, a region identified previously for breast cancer risk among Europeans. The association of this SNP with breast cancer risk remained highly statistically significant in Asians after adjusting for previously-reported SNPs in this region. In vitro experiments using both luciferase reporter and electrophoretic mobility shift assays demonstrated functional significance of this SNP. These results provide strong evidence implicating rs4784227 as a functional causal variant for breast cancer in the locus 16q12.1 and demonstrate the utility of conducting genetic association studies in populations with different genetic architectures

Replication and Functional Genomic Analyses of the Breast Cancer Susceptibility Locus at 6q25.1 Generalize Its Importance in Women of Chinese, Japanese, and European Ancestry

We evaluated the generalizability of a single nucleotide polymorphism (SNP), rs2046210 (A/G allele), associated with breast cancer risk that was initially identified at 6q25.1 in a genome-wide association study conducted among Chinese women. In a pooled analysis of over 31,000 women of East-Asian, European, and African ancestry, we found a positive association for rs2046210 and breast cancer risk in Chinese women [ORs (95%CI)=1.30(1.22–1.38) and 1.64(1.50–1.80) for the AG and AA genotypes, respectively, P for trend = 1.54 × 10−30], Japanese women [ORs (95%CI)=1.31(1.13–1.52) and 1.37(1.06–1.76), P for trend = 2.51 × 10−4], and European-ancestry American women [ORs (95%CI)=1.07(0.99–1.16) and 1.18(1.04–1.34), P for trend = 0.0069]. No association with this SNP, however, was observed in African American women [ORs (95%CI)=0.81(0.63–1.06) and 0.85(0.65–1.11) for the AG and AA genotypes, respectively, P for trend = 0.4027). In vitro functional genomic studies identified a putative functional variant, rs6913578. This SNP is 1,440 bp downstream of rs2046210 and is in high LD with rs2046210 in Chinese (r2=0.91) and European-ancestry (r2=0.83) populations, but not in Africans (r2=0.57). SNP rs6913578 was found to be associated with breast cancer risk in Chinese and European-ancestry American women. After adjusting for rs2046210, the association of rs6913578 with breast cancer risk in African Americans approached borderline significance. Results from this large consortium study confirmed the association of rs2046210 with breast cancer risk among women of Chinese, Japanese, and European ancestry. This association may be explained in part by a putatively functional variant (rs6913578) identified in the region

Transforming Growth Factor β (TGF-β)-Smad Target Gene Protein Tyrosine Phosphatase Receptor Type Kappa Is Required for TGF-β Function

Transforming growth factor β (TGF-β) inhibits proliferation and promotes cell migration. In TGF-β-treated MCF10A mammary epithelial cells overexpressing HER2 and by chromatin immunoprecipitation, we identified novel Smad targets including protein tyrosine phosphatase receptor type kappa (PTPRK). TGF-β up-regulated PTPRK mRNA and RPTPκ (receptor type protein tyrosine phosphatase kappa, the protein product encoded by the PTPRK gene) protein in tumor and nontumor mammary cells; HER2 overexpression down-regulated its expression. RNA interference (RNAi) of PTPRK accelerated cell cycle progression, enhanced response to epidermal growth factor (EGF), and abrogated TGF-β-mediated antimitogenesis. Endogenous RPTPκ associated with EGF receptor and HER2, resulting in suppression of basal and ErbB ligand-induced proliferation and receptor phosphorylation. In MCF10A/HER2 cells, TGF-β enhanced cell motility, FAK phosphorylation, F-actin assembly, and focal adhesion formation and inhibited RhoA activity. These responses were abolished when RPTPκ was eliminated by RNA interference (RNAi). In cells expressing RPTPκ RNAi, phosphorylation of Src at Tyr527 was increased and (activating) phosphorylation of Src at Tyr416 was reduced. These data suggest that (i) RPTPκ positively regulates Src; (ii) HER2 signaling and TGF-β-induced RPTPκ converge at Src, providing an adequate input for activation of FAK and increased cell motility and adhesion; and (iii) RPTPκ is required for both the antiproliferative and the promigratory effects of TGF-β

Gene trap and gene inversion methods for conditional gene inactivation in the mouse-0

<p><b>Copyright information:</b></p><p>Taken from "Gene trap and gene inversion methods for conditional gene inactivation in the mouse"</p><p>Nucleic Acids Research 2005;33(2):e14-e14.</p><p>Published online 19 Jan 2005</p><p>PMCID:PMC548374.</p><p>© 2005, the authors © </p

Association of Genetic Polymorphisms in Cell-Cycle Control Genes and Susceptibility to Endometrial Cancer Among Chinese Women

Although genetic variations in cell-cycle control genes have been previously linked to cancer risk, no study has specifically evaluated the role of these gene variants in endometrial carcinogenesis. Using data from the Shanghai Endometrial Cancer Study, a population-based case-control study with 1,199 cases and 1,212 age-matched controls (1997–2003), the authors carried out a systematic evaluation of the association of cell-cycle control genes with endometrial cancer risk. Sixty-five tagging or potentially functional single nucleotide polymorphisms in the CCNB1, CCND1, CCNE1, CDK2, CDK4, CDK6, CDKN1A, CDKN1B, and CDKN2A genes were genotyped and evaluated. Three single nucleotide polymorphisms in the CDKN1B gene (rs11055027, rs3759216, and rs34330) were related to endometrial cancer risk, although only the association with rs34330 remained statistically significant after adjustment for multiple comparisons. The odds ratios for rs34330 were 1.33 (95% confidence interval (CI): 1.06, 1.66) and 1.51 (95% CI: 1.16, 1.94) for the CT and TT genotypes, respectively, compared with the CC genotype. In vitro luciferase reporter assays showed that the minor allele (A) in rs3759216, which was associated with decreased endometrial cancer risk (odds ratio = 0.73, 95% CI: 0.56, 0.94) without adjustment for multiple comparisons, significantly increased promoter activity. These findings suggest that polymorphisms of the CDKN1B gene may play a role in endometrial carcinogenesis