Lung cancer remains the most lethal of all cancers. Survival from lung cancer is related to stage at presentation. As localized tumors generally do not cause symptoms, the disease is usually diagnosed at advanced stages when the prognosis is poor. As a result, the overall 5-year lung cancer survival rate is only 15%. Therefore, early detection is essential to improve survival and prognosis. It is well known that epigenetic alterations at CpG islands are associated with cancer. These epigenetic hypermethylations can be potential biomarkers for lung cancer risk or possibly early detection. Our goal for this study is to identify DMA promoter hypermethylation as markers of early detection of lung cancer. We previously reported hypermethylation at 21 genes in lung tumor tissues after genome-wide restriction landmark genomic scanning (RLGS) determined that CpG islands at these loci were differentially methylated compared to adjacent non-involved tissue. In contrast to non-specific hypermethylation in both tumor and non-involved adjacent tissue, silenced loci that are methylated in tumor but not in adjacent noninvolved tissue may be critical to carcinogenesis. The hypothesis of this study is that neoplastic progression in lung cancer is characterized by progressive epigenetic silencing associated with promoter hypermethylation at specific loci. We propose to compare RLGS differential methylation of lung tumors, adjacent precursor lesions and normal lung tissues resected from lung cancer patients. The resulting data will identify the specific CpG island sequences frequently hypermethylated in the early stages of lung cancer. Then we will determine which among the differentially hypermethylated loci show lung cancer-associated gene silencing. Finally, using bisulfite modified sequencing, we will determine the extent of hypermethylation within the affected CpG islands. Methylation profiles in tumor/precursor/normal tissues will be compared within same patients, therefore, CpG island differential methylation represents cancer-specific epigenetic changes. These results may be of immense benefit towards the early diagnosis of lung cancer. We also can identify markers associated with progression, which may provide insight into the biological mechanism of lung cancer. The proposed study will generate data that will be the groundwork for larger studies to validate the use of the identified methylation sites to develop markers for early lung cancer diagnosis.
| Park, Jong Y; Kim, Donghwa; Yang, Mihi et al. (2013) Gene silencing of SLC5A8 identified by genome-wide methylation profiling in lung cancer. Lung Cancer 79:198-204 |
