Polymorphisms in DNA repair genes in lung cancer patients living in a coal-mining region.

Air pollutants and ionizing radiation are well-known carcinogens involved in the pathogenesis of lung cancer, and residents of coal-mining regions are exposed routinely to these agents. Polymorphisms in DNA repair genes may be associated with an increased risk of malignant transformation. We investigated associations between the risk of lung cancer in residents of the coal-mining region and polymorphisms in the genes APEX1 (rs1130409), hOGG1 (rs1052133), XRCC1 (rs25489, rs25487), XRCC2 (rs3218536), XRCC3 (rs861539), ADPRT/PARP1 (rs1136410), XPD/ERCC2 (rs13181), XPG/ERCC5 (rs17655), XPC (rs2228001), ATM (rs1801516), and NBS1 (rs1805794). Three hundred and forty residents of the Kemerovo Region (a coal-mining region of western Siberia) were lung cancer patients exposed to air pollutants and ionizing radiation (case) and 335 were healthy donors (control). Genotyping was performed by real-time PCR and allele-specific PCR. We discovered that polymorphisms in the XPD gene in men [log-additive model: odds ratio (OR) = 1.64, 95% confidence interval (CI): 1.17-2.31], the ATM gene in women and nonsmokers (codominant model: OR = 0.11, 95% CI: 0.02-0.49 and OR = 0.25, 95% CI: 0.08-0.72, respectively), the APEX1 gene for smokers (recessive model: OR = 2.55, 95% CI: 1.34-4.85), and the NBS1 gene for those who work in the coal industry (overdominant model: OR = 0.40, 95% CI: 0.21-0.75) are associated with an increased risk of lung cancer. Using the multifactor dimensionality reduction method, we found a model of gene-gene interactions associated with the risk of lung cancer: NBS1 (rs1805794)-XRCC1 (rs25487)-hOGG1 (rs1052133)-XPG (rs17655). These results indicate an association between combinations of polymorphisms in the studied genes and the risk of lung cancer in residents of a coal-mining region.

Chromosome aberrations in peripheral blood lymphocytes of lung cancer patients exposed to radon and air pollution.

Lung cancer is one of the most common forms of cancer. The aim of this study was to validate chromosome aberrations in peripheral blood lymphocytes of lung cancer patients living in a region with high air pollution and increased background radon levels as a biomarker of cancer risk. A total of 417 lung cancer patients and 468 control participants were analysed using a chromosome aberration assay in peripheral blood lymphocytes. The results showed that chromatid-type aberrations (2.26±1.58 vs. 1.60±1.58) and chromosome-type aberrations (CSAs) (0.96±1.36 vs. 0.42±0.70) in lung cancer patients were increased significantly in comparison with the controls. The most significant two-fold increase was detected for CSAs (nonsmoking patients: 0.84±1.54 vs. 0.41±0.73%, smoking patients: 0.99±1.31 vs. 0.44±0.67%). The frequency of dicentric and ring chromosomes, double minutes and rogue cells was significantly higher (P=0.002, 0.00002, 0.01, 0.0007) in the lung cancer patients. As both analysed groups lived in the same environment, our results show that increased radon levels were not the only source for the detected genome damage. Using binomial logistic regression, the estimated odds ratios and 95% confidence intervals adjusted for the main confounders (smoking, occupational exposure, age) were 1.31 (1.20-1.40) for chromatid-type aberrations, 1.28 (1.17-1.33), and 1.68 (1.49-1.88) for CSAs. It may be suggested that lung cancer patients show a significant increase in genome damage that may be caused by an interplay between exposure and individual low capacity of DNA repair, leading to genome instability.

Polymorphisms of GSTM1, GSTT1, GSTP1 genes and chromosomal aberrations in lung cancer patients.

PURPOSE: To study the potential links between genetic polymorphisms in the GSTT1, GSTM1, GSTP1 genes and the frequency of chromosomal aberrations (CAs) in lung cancer patients and healthy residents in Russian Federation. METHODS: 200 cells in well-spread metaphase with 46 chromosomes were examined for 353 newly diagnosed lung cancer patients (males) who received medical treatment in the Kemerovo Regional Oncology Center (Kemerovo, Russian Federation), and 300 healthy males from Kemerovo, Russian Federation. The polymorphisms of the GSTM1 del and GSTT1 del genes were analysed by multiplex PCR. Genotyping of the polymorphic variants in the GSTP1 (A313G, T341C) gene was performed using Real-time PCR with competing TaqMan probes complementary to the polymorphic DNA sites. The data analysis was performed using software STATISTICA 8.0 (StatSoft Inc., USA). RESULTS: We discovered that a GSTM1 del polymorphism increases the frequency of chromosomal damage in smoking patients with lung cancer, a general group of lung cancer patients, donors with non-small cell lung cancer and patients in the latest stages of the malignant process. The synergetic effects of occupational exposure and the malignant process can induce some modifications in the cytogenetic status in lung cancer patients harbouring the GSTM1 del polymorphism. CONCLUSIONS: CAs in peripheral blood lymphocytes can be used as biomarkers of the early biological effects of exposure to genotoxic carcinogens and may predict future cancer incidence in several epidemiologic studies. Genetic changes in genes encoding phase II detoxification enzymes are linked to decreases in the metabolic detoxification of environmentally derived genotoxic carcinogens.