Numerical abnormalities of chromosome 9 and p16CDKN2A gene deletion detected by FISH in non-small cell lung cancer.

Background: Lung cancer is one of the most common types of cancer worldwide and its pathogenesis is closely associated with various environmental exposures and gene alterations. The identification of genetic changes is a useful strategy toward understanding tumourigenesis and specific genetic associations. Since the tumor suppressor gene p16 located at 9p21 chromosomal region might have an important role in lung carcinogenesis, the aim of the present study was to investigate p16 gene alterations and numerical aberrations of chromosome 9 in non-small cell lung cancer.

Materials And Methods: Nineteen cases of non-small cell lung cancer (11 squamous cell carcinomas, 6 adenocarcinomas and 2 large cell carcinomas) were investigated by fluorescence in situ hybridization (FISH) technique using a DNA p16 probe and alpha-satellite probe specific for chromosome 9.

Results: Polysomy 9 was found in 13 cases (6/11 squamous cell carcinomas, 5/6 adenocarcinomas and 2/2 large cell carcinomas). p16 gene alterations were found in 16 cases. Among them, deletion of p16 gene was found in 15 cases (8/11 squamous cell carcinomas, 5/6 adenocarcinomas and 2/2 large cell carcinomas). In six cases with p16 gene deletion, homozygous deletion was observed.

Conclusion: Numerical aberrations of chromosome 9 and p16 gene deletion are common findings in all subtypes of non-small cell lung cancer. Despite suggesting the p16 gene in the 9p chromosomal region plays a role in lung carcinogenesis, the presence of other oncogenes reflected by polysomy 9 participating in the neoplastic process cannot be excluded. Data of the present study also suggest, that there might not be a fundamental relationship between genetic changes and histological subtype of non-small cell lung cancer.