Analysis of Methylation Patterns of Some Tumor Suppressor Genes in Non-Small Cell Lung Cancer Using the Multiplex Ligation-Dependent Probe Amplification (MLPA) Method Küçük Hücreli Olmayan Akciğer Kanserleriyle İlişkilendirilmiş Tumor Süpressör Genlerin Multiplex Ligation-Dependent Probe Amplification (MLPA) Yöntemi ile Metilasyon Paternlerinin İncelenmesi

Lung cancer has the leading mortality rate among all cancer types and is the second most common cause of death after cardiovascular diseases. Apart from being an epigenetic mechanism, methylation is also a molecular mechanism which inhibits cancer-related gene expression although there is no mutation at DNA level. The aim of this study was to analyze a probe panel interrogated DNA for methylation patterns in 24 tumor suppressor genes in non-small cell lung cancer using the Methylation Specific- Multiplex Ligation-dependent Probe Amplification (MS-MLPA) method the Multiplex Liga- tion-dependent Probe Amplification (MLPA) method. Previously examined clinically and histopathologically diagnosed a hundred cases with "non-small cell lung cancer"were included into the study. The DNAs were extracted samples from both cancerous tissues of the cases and their corresponding control tissues. The relations of the methylation profile to clinicopathological factors in NSCLC were evaluated. The genes frequently methylated in NSCLC including CDKN2B, BRCA1, CDH13 and HIC1 were also hypermethylated in surrounding nontumorous lung tissues. However, hypermethylated APC, CDKN2A, MLH1, RARB, CHFR and GSTP1 probe regions were only specific to the tumorous tissues of the cases. The aberrant methylation profile of the CDH13 probe region was only detected in the surrounding normal tissues and the difference was statistically significant. Methylation rates for ATM, RARB, CDKN2B, HIC1, CDKN1B, PTEN, VHL and APC were different between squamous and adenocarcinomas. Almost all hypermethylated probe regions were detected in higher grade tumors but CDKN2B hypermethylation seemed to be an early event in NSCLCs. In conclusion, MS-MLPA can be used to determine aberrant methylation patterns of specific genes in lung tumors. However, since MS-MLPA is a screening test, the confirmation and expression analysis by using different ap- proaches are necessary.