Association between XRCC3 Thr241Met polymorphism and nasopharyngeal carcinoma risk: evidence from a large-scale case-control study and a meta-analysis.

The X-ray repair cross-complementing group 3 (XRCC3) Thr241Met polymorphism (rs861539, C > T) has drawn wide attentions as its association with cancer risk and its involvement in DNA repair. Several studies have attempted to link rs861539 to nasopharyngeal cancer (NPC) risk; however, the sample sizes of these studies are small and the results are controversial. To investigate the relationship of rs861539 and NPC susceptibility, we conducted a large-scale case-control study involving 4001 NPC cases and 2967 controls of southern Chinese. Logistic regression analysis revealed significant association for rs861539 and NPC risk under the recessive model (TT vs. CT + CC) with adjustment of age and gender (odds ratio, OR = 2.72; 95 % CI 1.10-6.72; P = 0.03). Further, meta-analysis involving 4457 NPC cases and 4132 controls from four studies showed consistent association of TT carriers and NPC risk (OR = 3.12; 95 % CI 1.58-6.13; P = 0.001). Taken together, our findings based on large-scale sample size suggested rs861539 at XRCC3 to be associated with NPC risk through recessive model.

[Advances in development of gene-gene interaction analysis methods based on SNP data: a review].

The SNP-based association analysis has become one of the most important approaches to interpret the underlying molecular mechanisms for human complex diseases. Nevertheless, the widely-used singe-locus analysis is only capable of capturing a small portion of susceptible SNPs with prominent marginal effects, leaving the important genetic component, epistasis or joint effects, to be undetectable. Identifying the complex interplays among multiple genes in the genome-wide context is an essential task for systematically unraveling the molecular mechanisms for complex diseases. Many approaches have been used to detect genome-wide gene-gene interactions and provided new insights into the genetic basis of complex diseases. This paper reviewed recent advances of the methods for detecting gene-gene interaction, categorized into three types, model-based and model-free statistical methods, and data mining methods, based on their characteristics in theory and numerical algorithm. In particular, the basic principle, numerical implementation and cautions for application for each method were elucidated. In addition, this paper briefly discussed the limitations and challenges associated with detecting genome-wide epistasis, in order to provide some methodological consultancies for scientists in the related fields.

Germline Polymorphisms and Length of Survival of Nasopharyngeal Carcinoma: An Exome-Wide Association Study in Multiple Cohorts.

Germline polymorphisms are linked with differential survival outcomes in cancers but are not well studied in nasopharyngeal carcinoma (NPC). Here, a two-phase association study is conducted to discover germline polymorphisms that are associated with the prognosis of NPC. The discovery phase includes two consecutive hospital cohorts of patients with NPC from Southern China. Exome-wide genotypes at 246 173 single nucleotide polymorphisms (SNPs) are determined, followed by survival analysis for each SNP under Cox proportional hazard regression model. Candidate SNP is replicated in another two independent cohorts from Southern China and Singapore. Meta-analysis of all samples (n = 5553) confirms that the presence of rs1131636-T, located in the 3'-UTR of RPA1, confers an inferior overall survival (HR = 1.33, 95% CI = 1.20-1.47, P = 6.31 × 10-8). Bioinformatics and biological assays show that rs1131636 has regulatory effects on upstream RPA1. Functional studies further demonstrate that RPA1 promotes the growth, invasion, migration, and radioresistance of NPC cells. Additionally, miR-1253 is identified as a suppressor for RPA1 expression, likely through regulation of its binding affinity to rs1131636 locus. Collectively, these findings provide a promising biomarker aiding in stratifying patients with poor survival, as well as a potential drug target for NPC.

X-chromosome association study reveals genetic susceptibility loci of nasopharyngeal carcinoma.

BACKGROUND: The male predominance in the incidence of nasopharyngeal carcinoma (NPC) suggests the contribution of the X chromosome to the susceptibility of NPC. However, no X-linked susceptibility loci have been examined by genome-wide association studies (GWASs) for NPC by far. METHODS: To understand the contribution of the X chromosome in NPC susceptibility, we conducted an X chromosome-wide association analysis on 1615 NPC patients and 1025 healthy controls of Guangdong Chinese, followed by two validation analyses in Taiwan Chinese (n = 562) and Malaysian Chinese (n = 716). RESULTS: Firstly, the proportion of variance of X-linked loci over phenotypic variance was estimated in the discovery samples, which revealed that the phenotypic variance explained by X chromosome polymorphisms was estimated to be 12.63% (non-dosage compensation model) in males, as compared with 0.0001% in females. This suggested that the contribution of X chromosome to the genetic variance of NPC should not be neglected. Secondly, association analysis revealed that rs5927056 in DMD gene achieved X chromosome-wide association significance in the discovery sample (OR = 0.81, 95% CI 0.73-0.89, P = 1.49 × 10-5). Combined analysis revealed rs5927056 for DMD gene with suggestive significance (P = 9.44 × 10-5). Moreover, the female-specific association of rs5933886 in ARHGAP6 gene (OR = 0.62, 95%CI: 0.47-0.81, P = 4.37 × 10-4) was successfully replicated in Taiwan Chinese (P = 1.64 × 10-2). rs5933886 also showed nominally significant gender × SNP interaction in both Guangdong (P = 6.25 × 10-4) and Taiwan datasets (P = 2.99 × 10-2). CONCLUSION: Our finding reveals new susceptibility loci at the X chromosome conferring risk of NPC and supports the value of including the X chromosome in large-scale association studies.

Genomic and transcriptomic landscapes of Epstein-Barr virus in extranodal natural killer T-cell lymphoma.

Extranodal natural killer T-cell lymphoma (nasal type; NKTCL) is an aggressive malignancy strongly associated with Epstein-Barr virus (EBV) infection. However, the role of EBV in NKTCL development is unclear, largely due to the lack of information about EBV genome and transcriptome in NKTCL. Here, using high-throughput sequencing, we obtained whole genome (n = 27) and transcriptome datasets (n = 18) of EBV derived from NKTCL tumor biopsies. We assembled 27 EBV genomes and detected an average of 1,152 single nucleotide variants and 44.8 indels (<50 bp) of EBV per sample. We also identified frequent focal EBV genome deletions and integrated EBV fragments in the host genome. Moreover, Phylogenetic analysis revealed that NKTCL-derived EBVs are closely clustered; transcriptome analysis revealed less activation of both latent and lytic genes and larger amount of T-cell epitope alterations in NKTCL, as compared with other EBV-associated cancers. Furthermore, we observed transcriptional defects of the BARTs miRNA by deletion, and the disruption of host NHEJ1 by integrated EBV fragment, implying novel pathogenic mechanisms of EBV. Taken together, we reported for the first time global mutational and transcriptional profiles of EBV in NKTCL clinical samples, revealing important somatic events of EBV and providing insights to better understanding of EBV's contribution in tumorigenesis.

The Heterogeneity Between Lynch-Associated and Sporadic MMR Deficiency in Colorectal Cancers.

Background: Previous studies demonstrated that prognosis of germline deficiency in mismatch repair protein (dMMR) was different from that of sporadic dMMR. The underlying mechanism has not been studied. Methods: From a prospectively maintained database, we collected dMMR colorectal cancer (CRC) patients identified by postoperative immunohistochemistry screening. According to genetic test, patients were grouped as Lynch-associated or sporadic dMMR. We compared the clinical-pathological features, prognosis, and immunoreactive differences between the two groups. By whole-exome sequencing and neoantigen detection pipeline, mutational frequencies and neoantigen burdens were also compared. All statistical tests were two-sided. Results: Sixty-seven sporadic dMMR and 85 Lynch-associated CRC patients were included in the study. Sporadic dMMR patients were older (P < .001) and their tumors were poorly differentiated (P = .03). The survival was better in the Lynch-associated group (P = .001). After adjustment, the difference still remained statistically significant (hazard ratio = 0.29, 95% confidence interval = 0.09 to 0.95, P = .04). The scores of Crohn's-like reaction (CRO; P < .001), immunoreactions in the invasive margin (IM; P = .01), tumor stroma (TS; P = .009), and cancer nest (CN; P = .02) of the Lynch-associated group were statistically significantly higher. The numbers of CD3+, CD8+, Foxp3+ tumor-infiltrating lymphocytes (TILs) in IM; CD3+, CD4+ TILs in TS; and CD3+, CD4+, CD8+ TILs in CN were statistically significantly higher in Lynch-associated dMMR patients. Based on the 16 patients who under went whole-exome sequencing, there were also more somatic mutations and neoantigen burdens in the Lynch-associated group compared with the sporadic dMMR group (439/pt vs 68/pt, P = .006; 628/pt vs 97/pt, P = .009). Conclusions: There are heterogeneities in dMMR CRCs. Lynch-associated dMMR patients present with more somatic mutations and neoantigens compared with sporadic dMMR, which probably results in stronger immunoreactions and survival improvement.

Elevated transcriptional levels of aldolase A (ALDOA) associates with cell cycle-related genes in patients with NSCLC and several solid tumors.

BACKGROUND: Aldolase A (ALDOA) is one of the glycolytic enzymes primarily found in the developing embryo and adult muscle. Recently, a new role of ALDOA in several cancers has been proposed. However, the underlying mechanism remains obscure and inconsistent. In this study, we tried to investigate ALDOA-associated (AA) genes using available microarray datasets to help elucidating the role of ALDOA in cancer. RESULTS: In the dataset of patients with non-small-cell lung cancer (NSCLC, E-GEOD-19188), 3448 differentially expressed genes (DEGs) including ALDOA were identified, in which 710 AA genes were found to be positively associated with ALDOA. Then according to correlation coefficients between each pair of AA genes, ALDOA-associated gene co-expression network (GCN) was constructed including 182 nodes and 1619 edges. 11 clusters out of GCN were detected by ClusterOne plugin in Cytoscape, and only 3 of them have more than three nodes. These three clusters were functionally enriched. A great number of genes (43/79, 54.4%) in the biggest cluster (Cluster 1) primarily involved in biological process like cell cycle process (Pa = 6.76E-26), mitotic cell cycle (Pa = 4.09E-19), DNA repair (Pa = 1.13E-04), M phase of meiotic cell cycle (Pa = 0.006), positive regulation of ubiquitin-protein ligase activity during mitotic cell cycle (Pa = 0.014). AA genes with highest degree and betweenness were considered as hub genes of GCN, namely CDC20, MELK, PTTG1, CCNB2, CDC45, CCNB1, TK1 and PSMB2, which could distinguish cancer from normal controls with ALDOA. Their positive association with ALDOA remained after removing the effect of HK2 and PKM, the two rate limiting enzymes in glycolysis. Further, knocking down ALDOA blocked breast cancer cells in the G0/G1 phase under minimized glycolysis. All suggested that ALDOA might affect cell cycle progression independent of glycolysis. RT-qPCR detection confirmed the relationship of ALDOA with CDC45 and CCNB2 in breast tumors. High expression of the hub genes indicated poor outcome in NSCLC. ALDOA could improve their predictive power. CONCLUSIONS: ALDOA could contribute to the progress of cancer, at least partially through its association with genes relevant to cell cycle independent of glycolysis. AA genes plus ALDOA represent a potential new signature for development and prognosis in several cancers.

Genetic susceptibility to the endemic form of NPC.

Nasopharyngeal carcinoma (NPC) is a malignancy with remarkably high prevalence in East Asia. Lines of evidence have suggested the involvement of genetic lesions in the etiology of NPC, together with the contributions of Epstein-Barr virus infection and environmental exposures. Linkage and association studies, either based on candidate genes or genome-wide levels, have been conducted to dissect the genetic variants that contribute to NPC risk. This review summarizes the current findings of genetic susceptibility to NPC, and points out some future challenges on discovery of other risk variants to explain the missing heritability of NPC.

Psychometric properties of the coronary heart disease scale of the quality-of-life instruments for chronic diseases (QLICD-CHD): an application to Cantonese patients.

The purpose of this study was to validate the applicability of our proposed disease-specific questionnaire to Cantonese coronary heart disease (CHD) patients. During the investigation from August 2010 to March 2012, 1000 Cantonese inpatients were recruited. The reliability of the scale was judged by the internal consistency, and the content and construct validity were assessed by using Pearson correlation and confirmatory factor analysis, respectively. Results showed that the Cronbach's α coefficient for the whole scale and most domains/facets were larger than .70 (.59 to .93). Most items had moderate to strong Pearson correlations with their respective facets (r > 0.50). Confirmatory factor analysis showed that the indices for goodness of fit were nearly acceptable. Overall, the QLICD-CHD scale has adequate psychometric properties when applied to Cantonese CHD patients.

Pathway-based analysis tools for complex diseases: a review.

Genetic studies are traditionally based on single-gene analysis. The use of these analyses can pose tremendous challenges for elucidating complicated genetic interplays involved in complex human diseases. Modern pathway-based analysis provides a technique, which allows a comprehensive understanding of the molecular mechanisms underlying complex diseases. Extensive studies utilizing the methods and applications for pathway-based analysis have significantly advanced our capacity to explore large-scale omics data, which has rapidly accumulated in biomedical fields. This article is a comprehensive review of the pathway-based analysis methods-the powerful methods with the potential to uncover the biological depths of the complex diseases. The general concepts and procedures for the pathway-based analysis methods are introduced and then, a comprehensive review of the major approaches for this analysis is presented. In addition, a list of available pathway-based analysis software and databases is provided. Finally, future directions and challenges for the methodological development and applications of pathway-based analysis techniques are discussed. This review will provide a useful guide to dissect complex diseases.