Refined-mapping of the novel TSG within the 17q24.3 chromosomal region in non-small cell lung cancer samples.
Lung cancer is a leading cause of cancer mortality in Taiwan. It has been previously demonstrated that alterations to tumor suppressor genes (TSGs) are involved in the multi-step carcinogenesis process that results in the development of human cancer, including lung cancer. Both copies of the TSG must be inactivated for their function to be lost. As a result, it is important to search for the genomic regions that potentially contain TSGs and to investigate the etiological association of lung cancer with the allelic deletion of various candidate TSGs. Previous genome-wide loss of heterozygosity (LOH) data has demonstrated that the chromosome region at 17q24.3 was a novel and frequent LOH region that was associated with non-small-cell lung cancer (NSCLC). In the present study, refined mapping using 9 additional microsatellite markers was performed targeting chromosome 17q24.3 by polymerase chain reaction (PCR)-LOH analysis. The allelic loss pattern across 48 available tumors indicates that the minimal deletion region was located between markers D17S1882 and D17S2193 and spanned a distance of approximately 2.7 Mb, reaching 65% LOH at locus D17S1816. A putative gene, LOC51321 (AMZ2), was postulated to be the deletion target on 17q24.3 based on the findings from these NSCLC samples. Reverse transcription-PCR (RT-PCR) expression analysis indicated reduced expression of LOC51321 in 54% (7/13) of the NSCLC cell lines tested and 36% (19/53) of the NSCLC tumor tissue samples analyzed. In CL1-5-F4 cells, low mRNA and protein expression of LOC51321 were associated with the promoter hypermethylation, as determined by RT-PCR, western blotting and methylation-specific PCR assays. In addition, treatment with 5-Aza-deoxycytosine successfully restored mRNA expression by de-methylating the putative promoter region in CL1-5-F4 cells that lacked LOC51321 expression, but did harbor the relevant methylated promoter. These findings indicate that LOC51321 may be involved in lung tumorigenesis.
Department of Biomedical Engineering, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei 11221, Taiwan, R.O.C.
Wayren
W
Huang
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan, R.O.C.
Yiching
Y
Wang
Department of Biomedical Engineering, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei 11221, Taiwan, R.O.C.
Woeichyn
W
Chu
Department of Molecular Biology and Human Genetics, College of Life Science, Tzu Chi University, Hualien 97004, Taiwan, R.O.C.
Ruochia
R
Tseng
DNA methylation; chromosome; deletion; marker; non-small cell lung cancer