Xiaoping Miao

Identification of genetic variants in base excision repair pathway and their associations with risk of esophageal squamous cell carcinoma.

The etiology of esophageal squamous cell carcinoma (ESCC) has been shown to be associated with genetic and certain environmental factors that produce DNA damage. Base excision repair (BER) genes are responsible for repair of DNA damage caused by reactive oxygen species and other electrophiles and therefore are good candidate susceptibility genes for ESCC. We first screened eight BER genes for new and potential functional polymorphisms by resequencing 27 DNA samples. We then identified and genotyped for important tagging single nucleotide polymorphisms (SNPs) in a case-control study of 419 patients with newly diagnosed esophageal cancer and 480 healthy controls by frequency matching on age and sex. The association between genotypes and ESCC risk was estimated by unconditional multivariate logistic regression analysis, and stepwise regression procedure was used for constructing the final logistic regression model. We identified 129 SNPs in the eight BER genes, including 18 SNPs that cause amino acid changes. In the final model, 4 SNPs, including 2 in the coding regions (ADPRT Val762Ala and MBD4 Glu346Lys) and others in noncoding regions (LIG3 A3704G and XRCC1 T-77C), remained as significant predictors for the risk of ESCC. The adjusted odd ratios were 1.25 [95% confidence interval (CI) 1.02–1.53] for the ADPRT 762Ala allele, 1.25 (95% CI 1.02–1.53) for the MBD4 346 Lys allele, 0.78 (95% CI 0.63–0.97) for the LIG3 3704G allele, and 1.38 (95% CI 1.01–1.89) for the XRCC1–77C allele. In addition, we observed a significant gene-gene interaction between XRCC1 Gln399Arg and ADPRT Val762Ala. The results suggest that the polymorphisms in five BER genes may be associated with the susceptibility to ESCC in a Chinese population.

Genome-wide association study identifies three new susceptibility loci for esophageal squamous-cell carcinoma in Chinese populations

Esophageal squamous-cell carcinoma (ESCC) is one of the most prevalent cancers worldwide and occurs at a relatively high frequency in China. To identify genetic susceptibility loci for ESCC, we conducted a genome-wide association study on 2,031 individuals with ESCC (cases) and 2,044 controls of Chinese descent using 666,141 autosomal SNPs. We evaluated promising associations in an additional 6,276 cases and 6,165 controls of Chinese descent from different areas of China. We identified seven susceptibility loci on chromosomes 5q11, 6p21, 10q23, 12q24 and 21q22 (ranging from P = 7.48 × 10−12 to P = 2.44 × 10−31); among these loci, 5q11, 6p21 and 21q22 were newly identified. Three variants in high linkage disequilibrium on 12q24 confer their risks to ESCC in a gene-lifestyle interaction manner, with more pronounced risk enhancement seen in tobacco and alcohol users. Furthermore, the identified variants had a cumulative association with ESCC risk (Ptrend = 7.92 × 10−56). These findings highlight the involvement of multiple genetic loci and gene-environment interaction in the development of esophageal cancer.

A genome-wide association study identifies new susceptibility loci for non-cardia gastric cancer at 3q13.31 and 5p13.1

Gastric cancer, including the cardia and non-cardia types, is the second leading cause of cancer-related deaths worldwide. To identify genetic risk variants for non-cardia gastric cancer, we performed a genome-wide association study in 3,279 individuals (1,006 with non-cardia gastric cancer and 2,273 controls) of Chinese descent. We replicated significant associations in an additional 6,897 subjects (3,288 with non-cardia gastric cancer and 3,609 controls). We identified two new susceptibility loci for non-cardia gastric cancer at 5p13.1 (rs13361707 in the region including PTGER4 and PRKAA1; odds ratio (OR) = 1.41; P = 7.6 × 10−29) and 3q13.31 (rs9841504 in ZBTB20; OR = 0.76; P = 1.7 × 10−9). Imputation analyses also confirmed previously reported associations of rs2294008 and rs2976392 on 8q24, rs4072037 on 1q22 and rs13042395 on 20p13 with non-cardia gastric cancer susceptibility in the Han Chinese population.

The role of P53 and MDM2 polymorphisms in the risk of esophageal squamous cell carcinoma.

The tumor suppressor P53 pathway plays a crucial role in preventing carcinogenesis and genetic variations of this pathway may be associated with cancer susceptibility. We tested this hypothesis by examining the contribution of functional polymorphisms in P53 and MDM2 to risk of esophageal squamous cell carcinoma (ESCC). DNA from 758 ESCC patients and 1,420 controls were genotyped for P53 codon 72Arg>Pro and MDM2 309T>G polymorphisms. Odds ratios (OR) and 95% confidence intervals (CI) of ESCC were estimated by logistic regression. We observed an increased risk of ESCC associated with the P53 Pro/Pro (OR, 1.83; 95% CI, 1.43-2.35; P < 0.001) or MDM2 GG (OR, 1.49; 95% CI, 1.16-1.91; P = 0.002) genotype, compared with the P53 Arg/Arg or MDM2 TT genotype, respectively. Interaction between these P53 and MDM2 polymorphisms increased risk of ESCC in a multiplicative manner, with the OR being 3.10 (95% CI, 2.07-4.69) for subjects carrying both P53 Pro/Pro and MDM2 GG genotypes. Significant interactions were observed between these polymorphisms and smoking, with risk being the highest (OR, 5.29; 95% CI, 2.91-9.61) in smokers having both P53 Pro/Pro and MDM2 GG genotypes. The MDM2 GG genotype was also associated with risk of developing poorly differentiated and advanced ESCC compared with the GT or TT genotype (OR for high-grade and stages III-IV versus low-grade and stages I-II = 1.60; 95% CI, 1.00-2.64; P = 0.049). The P53 and MDM2 polymorphisms may be genetic determinants for the development of ESCC.

Genome-wide association analyses of esophageal squamous cell carcinoma in Chinese identify multiple susceptibility loci and gene-environment interactions

We conducted a genome-wide association study (GWAS) and a genome-wide gene-environment interaction analysis of esophageal squamous-cell carcinoma (ESCC) in 2,031 affected individuals (cases) and 2,044 controls with independent validation in 8,092 cases and 8,620 controls. We identified six new ESCC susceptibility loci, of which four, at chromosomes 4q23, 16q12.1, 22q12 and 3q27 had a significant marginal effect (P = 1.78 × 10−39 to P = 2.49 × 10−11) and two of which, at 2q22 and 13q33, had a significant association only in the gene–alcohol drinking interaction (gene-environment interaction P (PG × E) = 4.39 × 10−11 and PG × E = 4.80 × 10−8, respectively). Variants at the 4q23 locus, which includes the ADH cluster, each had a significant interaction with alcohol drinking in their association with ESCC risk (PG × E = 2.54 × 10−7 to PG × E = 3.23 × 10−2). We confirmed the known association of the ALDH2 locus on 12q24 to ESCC, and a joint analysis showed that drinkers with both of the ADH1B and ALDH2 risk alleles had a fourfold increased risk for ESCC compared to drinkers without these risk alleles. Our results underscore the direct genetic contribution to ESCC risk, as well as the genetic contribution to ESCC through interaction with alcohol consumption.

Functional Haplotypes in the Promoter of Matrix Metalloproteinase-2 Predict Risk of the Occurrence and Metastasis of Esophageal Cancer

Matrix metalloproteinase-2 (MMP-2) plays important roles in cancer development and aggression. Our previous studies revealed a strong association between the MMP-2 −1306C/T polymorphism and risk of several cancers. A novel −735C/T polymorphism in MMP-2 promoter has been identified but the function is undefined. This study examined our hypothesis that these two polymorphisms might have functional relevance and impact on risk of esophageal squamous cell carcinoma in the context of haplotype. Genotypes and haplotypes were analyzed in 527 cases and 777 controls and odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. The function of the polymorphisms was examined by electrophoretic mobility shift assays, luciferase gene expression assays, and reverse transcriptase-PCR analyses. It was found that the −735C→T transition disrupts an Sp1 site and displays a lower promoter activity. The C-1306–C-735 haplotype had 7-fold increased luciferase expression and 3.7-fold increased MMP-2 mRNA levels in esophageal tissues compared with the T-1306–T-735 haplotype. A case-control analysis revealed a 1.52-fold (95% CI = 1.17–1.96) or 1.30-fold (95% CI = 1.04–1.63) excess risk of developing esophageal squamous cell carcinoma for the −1306CC or −735CC genotype carriers compared with noncarriers, respectively. A greater association was observed between elevated risk of developing esophageal squamous cell carcinoma and C-1306 or C-735 allele containing haplotypes, with the risk being highest for the C-1306–C-735 haplotype compared with the T-1306–T-735 haplotype (OR = 6.53; 95% CI = 2.78–15.33). The C-1306–C-735 haplotype was also associated with increased risk for distant metastasis of esophageal squamous cell carcinoma (OR = 3.34; 95% CI = 1.16–9.63). These findings suggest that the C-1306–C-735 haplotype in the MMP-2 promoter contributes to risk of the occurrence and metastasis of esophageal squamous cell carcinoma by increasing expression of MMP-2.

Genome-wide association study identifies NRG1 as a susceptibility locus for Hirschsprung's disease

Hirschsprungs disease (HSCR), or aganglionic megacolon, is a congenital disorder characterized by the absence of enteric ganglia in variable portions of the distal intestine. RET is a well-established susceptibility locus, although existing evidence strongly suggests additional loci contributing to sporadic HSCR. To identify these additional genetic loci, we carried out a genome-wide association study using the Affymetrix 500K marker set. We successfully genotyped 293,836 SNPs in 181 Chinese subjects with sporadic HSCR and 346 ethnically matched control subjects. The SNPs most associated with HSCR were genotyped in an independent set of 190 HSCR and 510 control subjects. Aside from SNPs in RET, the strongest overall associations in plausible candidate genes were found for 2 SNPs located in intron 1 of the neuregulin1 gene (NRG1) on 8p12, with rs16879552 and rs7835688 yielding odds ratios of 1.68 [CI95%:(1.40, 2.00), P = 1.80 × 10−8] and 1.98 [CI95%:(1.59, 2.47), P = 1.12 × 10−9], respectively, for the heterozygous risk genotypes under an additive model. There was also a significant interaction between RET and NRG1 (P = 0.0095), increasing the odds ratio 2.3-fold to 19.53 for the RET rs2435357 risk genotype (TT) in the presence of the NRG1 rs7835688 heterozygote, indicating that NRG1 is a modifier of HSRC penetrance. Our highly significant association findings are backed-up by the important role of NRG1 as regulator of the development of the enteric ganglia precursors. The identification of NRG1 as an additional HSCR susceptibility locus not only opens unique fields of investigation into the mechanisms underlying the HSCR pathology, but also the mechanisms by which a discrete number of loci interact with each other to cause disease.

Functional polymorphisms in cell death pathway genes FAS and FASL contribute to risk of lung cancer

Background: The FAS and FASL system plays a key role in regulating apoptotic cell death and corruption of this signalling pathway has been shown to participate in immune escape and tumorigenesis. There is reduced expression of FAS but elevated expression of FASL in many types of human cancers including lung cancer. We recently reported an association between functional polymorphisms in FAS (−1377G→A) and FASL (−844T→C) and risk of oesophageal cancer. Objective: To examine the contribution of these polymorphisms to risk of developing lung cancer. Methods: Genotypes of 1000 lung cancer patients and 1270 controls were analysed by PCR based restriction fragment length polymorphism. Associations with risk of lung cancer were estimated by logistic regression. Results: Compared with non-carriers, there was a 1.6 fold excess risk of developing lung cancer for carriers of the FAS −1377AA genotype (odds ratio (OR) 1.59, 95% confidence interval (CI) 1.21 to 2.10; p = 0.001), and 1.8 fold excess risk (OR 1.79, 95% CI 1.26 to 2.52; p = 0.001) for carriers of FASL −844CC. Gene–gene interaction of FAS and FASL polymorphisms increased risk of lung cancer in a multiplicative manner (OR for the carriers of both FAS −1377AA and FASL −844CC genotypes 4.18, 95% CI 2.83 to 6.18). Gene–environment interaction of FAS or FASL polymorphism and smoking associated with increased risk of lung cancer was also found. Conclusion: These results are consistent with our initial findings in oesophageal cancer and further support the hypothesis that the FAS and FASL triggered apoptosis pathway plays an important role in human carcinogenesis.

Polymorphisms of DNA repair genes XRCC1 and XPD and their associations with risk of esophageal squamous cell carcinoma in a Chinese population

Esophageal squamous cell carcinoma (ESCC), which is prevalent in China, is believed to be induced by environmental carcinogens. Accumulating evidence has shown that individual variation in DNA repair capacity resulting from genetic polymorphism influences risk of environmental carcinogenesis. We therefore investigated the associations between genetic polymorphisms in the DNA repair genes XRCC1 (Arg194Trp and Arg399Gln) and XPD (Asp312Asn and Lys751Gln) and risk of ESCC in an at‐risk Chinese population. Genotypes were determined by a PCR‐based approach in 433 patients with ESCC and 524 frequency‐matched normal controls. We found that individuals with Trp/Trp genotype at XRCC1 Arg194Trp site had a 2‐fold increased risk of this disease compared to Arg/Arg genotype (adjusted OR = 1.98; 95% CI 1.26–3.12). Furthermore, when compared to Arg/Arg and Arg/Trp genotype combined, homozygote for Trp/Trp genotype significantly increased the risk of developing ESCC, with the adjusted OR being 2.07 (95% CI 1.34–3.20). However, the XRCC1 Arg399Gln polymorphism was not significantly associated with risk of ESCC, with the adjusted OR being 0.87 (95% CI 0.55–1.37). Neither Asp312Asn nor Lys751Gln polymorphisms in the XPD gene influenced risk of ESCC in our study. These findings suggest that DNA repair gene XRCC1 but not XPD might play a role in esophageal carcinogenesis and might represent a genetic determinant in the development of the cancer.

FASL –844C polymorphism is associated with increased activation-induced T cell death and risk of cervical cancer

The FAS receptor–ligand system plays a key role in regulating apoptotic cell death, and corruption of this signaling pathway has been shown to participate in tumor-immune escape and carcinogenesis. We have recently demonstrated (Sun, T., X. Miao, X. Zhang, W. Tan, P. Xiong, and D. Lin. 2004. J. Natl. Cancer Inst. 96:1030–1036; Zhang, X., X. Miao, T. Sun, W. Tan, S. Qu, P. Xiong, Y. Zhou, and D. Lin. 2005. J. Med. Genet. 42:479–484) that functional polymorphisms in FAS and FAS ligand (FASL) are associated with susceptibility to lung cancer and esophageal cancer; however, the mechanisms underlying this association have not been elucidated. We show that the FAS –1377G, FAS –670A, and FASL –844T variants are expressed more highly on ex vivo–stimulated T cells than the FAS –1377A, FAS –670G, and FASL –844C variants. Moreover, activation-induced cell death (AICD) of T cells carrying the FASL –844C allele was increased. We also found a threefold increased risk of cervical cancer among subjects with the FASL –844CC genotype compared with those with the –844TT genotype in a case-control study in Chinese women. Together, these observations suggest that genetic polymorphisms in the FAS–FASL pathway confer host susceptibility to cervical cancers, which might be caused by immune escape of tumor cells because of enhanced AICD of tumor-specific T cells.