ABSTRACT
Background: Cancers arising within the gastrointestinal tract are complex disorders involving genetic events that cause the conversion of normal tissue to premalignant lesions and malignancy. Shared genetic features are reported in epithelial-based gastrointestinal cancers which indicate common susceptibility among this group of malignancies. In addition, the contribution of rare variants may constitute parts of genetic susceptibility. Methods: A cross-cancer analysis of 38,171 shared rare genetic variants from genome-wide association assays was conducted, which included data from 3,194 cases and 1,455 controls across three cancer sites (esophageal, gastric and colorectal). The SNP-level association was performed by multivariate logistic regression analyses for single cancer, followed by association analysis for SubSETs (ASSET) to adjust the bias of overlapping controls. Gene-level analyses were conducted by SKAT-O, with multiple comparison adjustments by false discovery rate (FDR). Based on the significant genes indicated by SKATO analysis, pathways analysis was conducted using Gene Ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome databases. Results: Meta-analysis in three gastrointestinal (GI) cancers identified 13 novel susceptibility loci that reached genome-wide significance (P ASSET< 5×10-8). SKAT-O analysis revealed EXOC6, LRP5L and MIR1263/LINC01324 to be significant genes shared by GI cancers (P adj<0.05, P FDR<0.05). Furthermore, GO pathway analysis identified significant enrichment of synaptic transmission and neuron development pathways shared by all three cancer types. Conclusion: Rare variants and the corresponding genes potentially contribute to shared susceptibility in different GI cancer types. The discovery of these novel variants and genes offers new insights for the carcinogenic mechanisms and missing heritability of GI cancers.
ABSTRACT
BACKGROUND: Lung cancer has the highest mortality among cancers, represented by a low 5-year survival rate. The function of the immune system has a profound influence on the development and progression of lung cancer. Thus genetic variants of the immune-related genes may serve as potential predictors of non-small cell lung cancer (NSCLC) survival. METHODS: In the present study, we conducted a two-stage survival analysis in 1,531 NSCLC patients and assessed the associations between genetic variants in the immune-activation gene set and the overall survival (OS) of NSCLC patients. The validated variants were further subjected to functional annotation and in vitro experiments. RESULTS: We identified 25 SNPs spanning six loci associated with NSCLC OS after multiple-testing corrections in all datasets, in which two variants, PSMA4 rs12901682 A > C and VAV2 rs12002767 C > T, were shown to potentially affect lung cancer OS by cis-regulating the expression of the corresponding genes [(HR (95% CI) = 0.76 (0.65-0.89) and 1.36 (1.12-1.65), p = 4.29 × 10-4 and 0.002, respectively]. CONCLUSION: Our findings provide new insights into the role of genetic variants in the immune-activation pathway genes in lung cancer progression.
