Effects of CYP1A1 and GSTM1 gene polymorphisms and BPDE-DNA adducts on lung cancer / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the effect of CYP1A1 and GSTM1 genetic polymorphisms and BPDE-DNA adducts on lung tumorigenesis.</p><p><b>METHODS</b>The case control study has included 200 cases of lung cancer and 200 controls. DNA was extracted from blood samples of all subjects. The genotype of both CYP1A1 and GSTM1 were detected with PCR-based restriction fragment length polymorphisms (PCR-RELP). BPDE-DNA adducts were detected with competitive ELISA.</p><p><b>RESULTS</b>CYP1A1 mutant genotype and GSTM1 null genotype with smoke has increased the risk of lung cancer, with OR being 2.406(1.321-4.382), 2.755(1.470-5.163), respectively. The level of BPDE-DNA adducts in patients was greater than control, and the adduct level in ever smokers was higher than never smokers, the difference was statistically significant (P= 0.0252). GSTM1 null genotype individuals with BPDE-DNA level higher than 5 adducts/10(8) nucleotide have increased risk of lung cancer (OR= 1.988, 95%CI: 1.011-3.912). Compared with never smokers with CYP1A1 wild genotype, smokers with CYP1A1 mutation genotype had an increased risk of forming a higher level of DNA adducts (P= 0.0459). Smokers with GSTM1 null genotype formed more DNA adducts compared with never smokers with GSTM1 functional genotype (OR = 2.432, 95% CI: 1.072-4.517).</p><p><b>CONCLUSION</b>GSTM1 null genotype with higher level DNA adducts may increase the risk of lung cancer. DNA adducts form easier in smokers with CYP1A1 mutation genotype and GSTM1 null genotype, which in turn may influence lung tumorigenesis.</p>

Correlation between RARbeta gene promoter methylation and P53 gene mutations in non-small cell lung cancer / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the correlation between RARbeta gene promoter methylation and P53 gene mutations in non-small cell lung cancer (NSCLC).</p><p><b>METHODS</b>Promoter methylation of RARbeta and P53 mutations of exons 5 through 9 in 198 resected primary NSCLC tissues were determined by methylation-specific PCR and direct sequencing.</p><p><b>RESULTS</b>RARbeta gene promoter methylation and P53 mutation were detected in 58.1% and 36.4% of tumors, respectively. Both were higher in males than in females and in smokers than in nonsmokers. A higher prevalence of RARbeta promoter methylation was found in patients with advanced stage tumors than those with TNM stage I. P53 gene mutations were more frequent in squamous cell carcinoma and adeno-squamous carcinoma than adenocarcinoma. All such differences were statistically significant (P< 0.05). Frequencies of P53 mutations, including G:C>T:A mutations, transversions and missense mutations were significantly higher in tumors with RARbeta methylation than in those without (P< 0.05). A significantly higher prevalence of RARbeta methylation was found in tumors with only G:C>T:A mutation in P53 gene than those without P53 mutations (P< 0.05). This difference (OR=3.737, 95%CI: 1.414-9.873) was still statistically significant (P< 0.05) in smokers (OR=4.020, 95%CI: 1.263-12.800), squamous cell carcinomas (OR=5.480, 95%CI: 1.400-21.446) or patients with advanced tumors (OR=3.446, 95%CI: 1.054-11.267) after adjusting for age and sex.</p><p><b>CONCLUSION</b>RARbeta methylation is associated with G:C>T:A mutations in P53 gene in NSCLC.</p>

Relationship between promoter methylation of p16, DAPK and RAR beta genes and the clinical data of non-small cell lung cancer / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the effects of promoter methylation of p16, death-associated protein kinase (DAPK) and retinoic acid receptor-beta (RAR beta) genes on clinical data in non-small cell lung cancers, and to study the effect of smoking on the risk of gene methylation.</p><p><b>METHODS</b>The promoter methylation of p16, DAPK and RAR beta genes in 200 primary non-small cell lung cancers and the corresponding nonmalignant lung tissues were determined by methylation-specific PCR.</p><p><b>RESULTS</b>Methylation in the tumor tissues was detected in 51.0% for p16, 60.0% for DAPK, and 58.0% for RAR beta gene, with significant differences (P < 0.05) when compared with those in the corresponding nonmalignant tissues(12.5%, 11.5% and 15.0%) respectively. p16 gene methylation in tumor tissue was associated with age significantly in unconditional logistic regression analysis (P < 0.01) and histologic type (P < 0.05). DAPK gene methylation in tumor tissue was associated significantly with age (P < 0.05), gender (P < 0.05) and clinical type (P < 0.05). RAR beta gene methylation in tumor tissue was associated with clinical type (P < 0.05) and tumor stage (P < 0.05) significantly. The interaction odds ratio (OR) for the gene-gene interaction in tumor tissue between p16 and DAPK was 1.987 (95%CI:1.055-3.743). The results of the gene-smoking analyses revealed that a relationship existed between cigarette smoking and p16 gene methylation (OR = 3.139, 95%CI: 1.046-9.419), the OR for the relationship of DAPK gene methylation and cigarette smoking was 3.585(95%CI: 1.270-10.123) in tumor tissue. The RAR beta gene methylation did not differ based on the smoking status of patients in tumor tissue.</p><p><b>CONCLUSION</b>The p16, DAPK and RAR beta genes methylation are strongly associated with clinical data of non-small cell lung cancer, and methylation of p16 and DAPK genes are associated with tobacco smoking.</p>