Comprehensive functional annotation of susceptibility variants identifies genetic heterogeneity between lung adenocarcinoma and squamous cell carcinoma / 医学前沿

Although genome-wide association studies have identified more than eighty genetic variants associated with non-small cell lung cancer (NSCLC) risk, biological mechanisms of these variants remain largely unknown. By integrating a large-scale genotype data of 15 581 lung adenocarcinoma (AD) cases, 8350 squamous cell carcinoma (SqCC) cases, and 27 355 controls, as well as multiple transcriptome and epigenomic databases, we conducted histology-specific meta-analyses and functional annotations of both reported and novel susceptibility variants. We identified 3064 credible risk variants for NSCLC, which were overrepresented in enhancer-like and promoter-like histone modification peaks as well as DNase I hypersensitive sites. Transcription factor enrichment analysis revealed that USF1 was AD-specific while CREB1 was SqCC-specific. Functional annotation and gene-based analysis implicated 894 target genes, including 274 specifics for AD and 123 for SqCC, which were overrepresented in somatic driver genes (ER = 1.95, P = 0.005). Pathway enrichment analysis and Gene-Set Enrichment Analysis revealed that AD genes were primarily involved in immune-related pathways, while SqCC genes were homologous recombination deficiency related. Our results illustrate the molecular basis of both well-studied and new susceptibility loci of NSCLC, providing not only novel insights into the genetic heterogeneity between AD and SqCC but also a set of plausible gene targets for post-GWAS functional experiments.

East meets West: ethnic differences in epidemiology and clinical behaviors of lung cancer between East Asians and Caucasians / 癌症

Lung cancer is the leading cause of cancer death worldwide, with large variation of the incidence and mortality across regions. Although the mortality of lung cancer has been decreasing, or steady in the US, it has been increasing in Asia for the past two decades. Smoking is the leading cause of lung cancer, and other risk factors such as indoor coal burning, cooking fumes, and infections may play important roles in the development of lung cancer among Asian never smoking women. The median age of diagnosis in Asian patients with lung cancer is generally younger than Caucasian patients, particularly among never-smokers. Asians and Caucasians may have different genetic susceptibilities to lung cancer, as evidenced from candidate polymorphisms and genome-wide association studies. Recent epidemiologic studies and clinical trials have shown consistently that Asian ethnicity is a favorable prognostic factor for overall survival in non-small cell lung cancer (NSCLC), independent of smoking status. Compared with Caucasian patients with NSCLC, East Asian patients have a much higher prevalence of epidermal growth factor receptor (EGFR) mutation (approximately 30% vs. 7%, predominantly among patients with adenocarcinoma and never-smokers), a lower prevalence of K-Ras mutation (less than 10% vs. 18%, predominantly among patients with adenocarcinoma and smokers), and higher proportion of patients who are responsive to EGFR tyrosine kinase inhibitors. The ethnic differences in epidemiology and clinical behaviors should be taken into account when conducting global clinical trials that include different ethnic populations.

Relationship between polymorphisms of genes encoding microsomal epoxide hydrolase and glutathione S-transferase P1 and chronic obstructive pulmonary disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD). However, only 10% - 20% of chronic heavy cigarette smokers develop symptomatic disease. COPD is most likely the result of complex interactions between environmental and genetic factors. Genetic susceptibility to COPD might depend on the variations in enzyme activities that detoxify cigarette smoke products, such as microsomal epoxide hydrolase (mEH) and glutathione S-transferase (GST). In this study, we investigated the relationship between polymorphisms in the genes encoding mEH and glutathione S-transferase P1 (GSTP1) and COPD in a Chinese population.</p><p><b>METHODS</b>Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to find mEH polymorphism in exon 3 (Tyr113-->His), exon 4 (His139-->Arg) and GSTP1 polymorphism in exon 5 (Ile105-->Val) in 100 COPD patients and 100 age- and sex-matched healthy controls.</p><p><b>RESULTS</b>The proportion of mEH exon 3 heterozygotes was significantly higher in patients with COPD than that in the control subjects (42% vs 32%). The odds ratio (OR) adjusted by age, sex, body mass index (BMI) and cigarette years was 2.96 (95% CI 1.24 - 7.09). There was no marked difference in very slow activity genotype versus other genotypes between COPD patients and the controls. When COPD patients were non-smokers, the OR of very slow activity genotype versus other genotypes was more than 1.00; and when COPD patients were smokers (current smokers and ex-smokers), the OR was less than 1.00. There was no significant difference in GSTP1 polymorphism adjusted by age, sex, BMI and smoking between COPD patients and the controls.</p><p><b>CONCLUSIONS</b>mEH exon 3 heterozygotes might be associated with susceptibility to COPD in China. The interaction might exist between mEH genotype and smoke. The gene polymorphism for GSTP1 might not be associated with susceptibility to COPD in the Chinese population.</p>