Xiaoyi Zhou

Genetic variants of miRNA sequences and non–small cell lung cancer survival

Recent evidence indicates that small noncoding RNA molecules known as microRNAs (miRNAs) can function as tumor suppressors and oncogenes. Mutation, misexpression, and altered mature miRNA processing are implicated in carcinogenesis and tumor progression. Because SNPs in pre-miRNAs could alter miRNA processing, expression, and/or binding to target mRNA, we conducted a systematic survey of common pre-miRNA SNPs and their surrounding regions and evaluated in detail the association of 4 of these SNPs with the survival of individuals with non-small cell lung cancer (NSCLC). When we assumed that disease susceptibility was inherited as a recessive phenotype, we found that the rs11614913 SNP in hsa-mir-196a2 was associated with survival in individuals with NSCLC. Specifically, survival was significantly decreased in individuals who were homozygous CC at SNP rs11614913. In the genotype-phenotype correlation analysis of 23 human lung cancer tissue samples, rs11614913 CC was associated with a statistically significant increase in mature hsa-mir-196a expression but not with changes in levels of the precursor, suggesting enhanced processing of the pre-miRNA to its mature form. Furthermore, binding assays revealed that the rs11614913 SNP can affect binding of mature hsa-mir-196a2-3p to its target mRNA. Therefore, the rs11614913 SNP in hsa-mir-196a2 may be a prognostic biomarker for NSCLC. Further characterization of miRNA SNPs may open new avenues for the study of cancer and therapeutic interventions.

Common genetic variants in pre-microRNAs were associated with increased risk of breast cancer in Chinese women.

Small, noncoding RNA molecules, called microRNAs (miRNAs), are thought to function as either tumor suppressors or oncogenes. Common single‐nucleotide polymorphisms (SNPs) in miRNAs may change their property through altering miRNA expression and/or maturation, and thus they may have an effect on thousands of target mRNAs, resulting in diverse functional consequences. However, it remains largely unknown whether miRNA SNPs may alter cancer susceptibility. We evaluated the associations of selected four SNPs (rs2910164, rs2292832, rs11614913, and rs3746444) in pre‐miRNAs (hsa‐mir‐146a, hsa‐mir‐149, hsa‐mir‐196a2, and hsa‐mir‐499) with breast cancer risk in a case‐control study of 1,009 breast cancer cases and 1,093 cancer‐free controls in a population of Chinese women and we found that hsa‐mir‐196a2 rs11614913:T>C and hsa‐mir‐499 rs3746444:A>G variant genotypes were associated with significantly increased risks of breast cancer (odds ratio [OR], 1.23; 95% confidence interval [CI], 1.02–1.48 for rs11614913:T>C; and OR, 1.25; 95% CI, 1.02–1.51 for rs3746444:A>G in a dominant genetic model) in a dose‐effect manner (P for trend was 0.010 and 0.037, respectively). These findings suggest, for the first time, that common SNPs in miRNAs may contribute to breast cancer susceptibility. Further functional characterization of miRNA SNPs and their influences on target mRNAs may provide underlying mechanisms for the observed associations and disease etiology. Hum Mutat 0, 1–6, 2008.

Functional Genetic Variations in Cytotoxic T-Lymphocyte Antigen 4 and Susceptibility to Multiple Types of Cancer

Antitumor T lymphocytes play a pivotal role in immunosurveillance of malignancy. The CTL antigen 4 (CTLA-4) is a vital negative regulator of T-cell activation and proliferation. This study examined whether genetic polymorphisms in CTLA-4 are associated with cancer susceptibility. A two-stage investigation using haplotype-tagging single nucleotide polymorphism approach and multiple independent case-control analyses was performed to assess the association between CTLA-4 genotypes and cancer risk. Functional relevance of the polymorphisms was examined by biochemical assays. We found that the 49G>A polymorphism in the CTLA-4 leading sequence causing (17)Ala to (17)Thr amino acid substitution is associated with increased susceptibility to multiple cancers, including lung, breast, esophagus, and gastric cardia cancers. Genotyping in 5,832 individuals with cancer and 5,831 control subjects in northern and southern Chinese populations showed that the CTLA-4 49AA genotype had an odds ratio of 1.72 (95% confidence interval, 1.50-2.10; P = 3.4 x 10(-7)) for developing cancer compared with the 49GG genotype. Biochemical analyses showed that CTLA-4-(17)Thr had higher capability to bind B7.1 and stronger inhibitory effect on T-cell activation compared with CTLA-4-(17)Ala. T cells carrying the 49AA genotype had significantly lower activation and proliferation rates compared with T cells carrying the 49GG genotype upon stimulation. These results are consistent with our hypothesis and indicate that genetic polymorphisms influencing T-cell activation modify cancer susceptibility.

Genetic variants in fibroblast growth factor receptor 2 (FGFR2) contribute to susceptibility of breast cancer in Chinese women

Fibroblast growth factor receptor 2 (FGFR2) belongs to the FGFR family, which plays an important role in cell growth, invasiveness, motility and angiogenesis. In human breast cancer, expression of FGFR2 is estrogen receptor (ER)-dependent and correlates with a lower rate of apoptosis. Recently, whole-genome association studies have identified several single-nucleotide polymorphisms (SNPs) of FGFR2 as novel breast cancer susceptibility loci. In the present study of 1049 breast cancer patients and 1073 cancer-free controls, we assessed whether polymorphisms of FGFR2 are associated with breast cancer risk in Chinese women and whether these associations are stronger in women with a reproductive history suggestive of greater exposure to endogenous estrogens. We genotyped three FGFR2 polymorphisms (rs2981582C/T, rs1219648A/G and rs2420946C/T) using the SNPstream 12-plex platform. Each of the three SNPs was significantly associated with increased breast cancer risk in a dose-dependent manner. Compared with women with 0-2 risk loci, those with 3 risk loci had a 1.36-fold increased odds of breast cancer (95% confidence interval = 1.13-1.62, P = 0.001). In stratified analyses, associations between the presence of 3 risk loci and breast cancer were stronger among women with ER- and/or progesterone receptor-positive cancers, premenopausal women and women with an older age at first live birth. Furthermore, there was a significant additive interaction between risk genotypes and menopausal status (P for multiplication interaction/additive interaction: 0.083/0.037). These findings indicate that genetic variants in FGFR2 may contribute to breast cancer occurrence in Chinese women, possibly through pathways related to estrogen and/or progesterone.

Interactions of IL-12A and IL-12B Polymorphisms on the Risk of Cervical Cancer in Chinese Women

Purpose: Accumulative evidence suggests that interleukin-12 (IL-12) plays a central role in the Th1 responses and thus participates in the carcinogenesis of human papillomavirus–related cervical cancer. We hypothesized that potentially functional polymorphisms in IL12A and IL12B may individually and jointly contribute to cervical cancer risk. Experimental Design: We genotyped IL12A rs568408 [3′ untranslated region (UTR) G>A] and rs2243115 (5′UTR T>G) and IL12B rs3212227 (3′UTR A>C) in a hospital-based study of 404 cervical cancer cases and 404 cancer-free controls. Results: The IL12A rs568408 GA/AA and IL12B rs3212227 AC/CC variant genotypes were associated with a significantly increased risk of cervical cancer [adjusted odds ratio, 1.43; 95% confidence interval (CI), 1.06-1.93; and adjusted odds ratio, 1.30; 95% CI, 0.97-1.75, respectively], compared with their corresponding wild-type homozygotes. Moreover, a significant gene-gene interaction of these 2 loci were evident in the risk of cervical cancer, and subjects carrying variant genotypes of both loci had a 1.82-fold (95% CI, 1.28-2.57) increased risk of cervical cancer. In the stratified analyses, the combined genetic effect was more pronounced in patients who had early-stage tumors or more parities. Subjects carrying rs568408 AG/AA and rs3212227 AC/CC genotypes and having >2 parities showed a 6.00-fold (95% CI, 2.86-12.56) elevated cervical cancer risk (P for multiplicative interaction = 0.046). Conclusion: These findings suggest that IL12A rs568408 and IL12B rs3212227 may individually and jointly contribute to the risk of cervical cancer and may modify cervical cancer risk associated with parity, but these data need further validation.

Association of Common PALB2 Polymorphisms with Breast Cancer Risk: A Case-Control Study

Purpose: The PALB2 gene has an essential role in BRCA2-mediated DNA double-strand break repair and intra–S phase DNA damage checkpoint control, and its mutations are moderately associated with breast cancer susceptibility. This study was designed to investigate the common variants of PALB2 and their association with breast cancer risk. Experimental Design: Four single nucleotide polymorphisms (SNP; rs249954, rs249935, rs120963, and rs16940342) which tagged all 19 of the reported SNPs (minor allele frequency >0.05) covering PALB2 were selected and genotyped in 1,049 patients with breast cancer and 1,073 cancer-free controls in a female Chinese population. Results: Based on the multiple hypothesis testing with the Benjamini-Hochberg method, tagging SNPs (tSNP) rs249954, rs120963, and rs16940342 were found to be associated with an increase of breast cancer risk (false discovery rate–adjusted P values of 0.004, 0.028, and 0.049, respectively) under the dominant model. tSNP rs249954 was associated with a 36% increase of breast cancer risk [adjusted odds ratio (OR), 1.36; 95% confidence intervals (CI), 1.13-1.64; P = 0.001; TT/TC versus CC genotypes]. The adjusted OR for rs120963 was 1.25 (95% CI, 1.04-1.49; P = 0.014; CC/CT versus TT genotypes). For rs16940342, the adjusted OR was 1.21 (95% CI, 1.02-1.45; P = 0.037; GG/GA versus AA genotypes). Based on an additive model, tSNPs rs249954 and rs120963 were associated with an increase of breast cancer risk (P = 0.005 and 0.019; respectively), with the false discovery rate–adjusted P values being 0.020 and 0.038, respectively. Conclusions: Our data suggest that the variants of PALB2 confer low-penetrance breast cancer susceptibility in a Chinese population.

Polymorphisms in HPV E6/E7 protein interacted genes and risk of cervical cancer in Chinese women: A case-control analysis☆

OBJECTIVE Accumulating studies indicate that HPV E6/E7 oncoproteins interacting genes, TP53, BRCA1 and BARD1, play a critical role in cervical carcinogenesis. We hypothesized that potentially functional polymorphisms in TP53, BRCA1 and BRAD1 may individually and/or jointly contribute to cervical cancer risk. METHODS We genotyped 4 single nucleotide polymorphisms (SNPs) with amino acid changes, TP53 Pro72Arg (rs1042522), BRCA1 Pro871Leu (rs799917), BARD1 Pro24Ser (rs1048108) and Arg378Ser (rs2229571), in a case-control study of 404 cervical cancer cases and 404 cancer-free controls in Chinese women. RESULTS Logistic regression analysis showed that the BRCA1 variant rs799917 TT genotype was associated with a significantly decreased risk of cervical cancer in a recessive genetic model (adjusted OR=0.62, 95% CI=0.40-0.95), compared with the genotypes CT/CC. However, no significant associations with cervical cancer were observed for other 3 SNPs (adjusted OR=1.01, 95% CI=0.68-1.50 for rs1048108 TT vs CT/CC; adjusted OR=1.04, 95% CI=0.67-1.64 for rs2229571 CC vs GG/GC; adjusted OR=0.84, 95% CI=0.59-1.20 for rs1042522 CC vs GG/GC). CONCLUSION These findings indicate that BRCA1 rs799917 polymorphism may contribute to the risk of cervical cancer in this Chinese population, and further validation in other populations are warranted.