We selected eight genes, ATM serine/threonine kinase gene (ATM), BRCA2, DNA repair associated gene (BRCA2), checkpoint kinase 2 gene (CHEK2), EGFR, parkin RBR E3 ubiquitin protein ligase gene (PARK2), telomerase reverse transcriptase gene (TERT), tumor protein p53 gene (TP53), and Yes associated protein 1 gene (YAP1), on the basis of prior anecdotal association with lung cancer or genome-wide association studies.
We identified large-effect genome-wide associations for squamous lung cancer with the rare variants BRCA2 p.Lys3326X (rs11571833, odds ratio (OR) = 2.47, P = 4.74 × 10(-20)) and CHEK2rs17879961" genes_norm="11200;8626">p.Ile157Thr (rs17879961, OR = 0.38, P = 1.27 × 10(-13)).
Several other genetic regions including variants of CHEK2 (22q12), TP53BP1 (15q15) and RAD52 (12p13) have been demonstrated to influence lung cancer risk in candidate- or pathway-based analyses.
For instance, a greater absolute risk reduction of lung and upper aerodigestive cancers in smokers than in non-smokers carrying the I157TCHEK2 variant has been observed, as has an interaction between TP53 intron 3 16-bp repeats and multiple X-ray exposures on lung cancer risk.
Based on the estimation from the hierarchical modeling, subjects who carried OGG1 326C/326C homozygotes, MGMT 143V or 178R, and CHEK2 157I had an odds ratio of lung cancer equal to 1.45 [95% confidence interval (95% CI), 1.05-2.00], 1.18 (95% CI, 1.01-1.40), and 1.58 (95% CI, 1.14-2.17).
We reported that the CHK2 expression is diminished or absent in both non-small cell lung cancer (NSCLC) cell lines and clinical lung cancer tumor specimens.
These findings confirm that the DNA damage checkpoint pathway involving CHK2 is indeed inactivated in this fatal adult cancer and also suggest that reduced expression of Chk2 may also be an important inactivating mechanism, contributing to the development of lung cancer.
We found that the CHK2 gene was somatically mutated in lung cancer in vivo, although at a low frequency, and that a previously undescribed shorter isoform of CHK1 was expressed preferentially in small cell lung cancer in a tumor-predominant manner.