Geographical Difference of Chromosome Aberrations between Japanese and American Small Cell Lung Cancer Cell Lines

Lung-cancer is the leading cause of cancer-related death worldwide. Cytogenetic analysis have been performed last two decades, but comparative analysis of karyotypes of small cell lung cancer (SCLC) from between Japan and America has not been precisely studied. Six Japanese and one American SCLC cell lines examined were hyperdiploid to neartetraploid with modal number of 52-91. These cells had a complex karyotype with more than 10 rearrangements. The karyotypic patterns were relatively consistent alterations involved long arm of chromosomes 1, 3, 7 and 11, and short arm of chromosomes 1 and 3. Higher rearrangements specially associated with translocations and deletions were observed in short and long arms of chromosomes 3 (3p21&3q25), and recurrently long arms of chromosome 7 (7q36 and 7q23). Although the chromosome of SCLC is too complex and G-banding analysis could not resolve all of many of the karyotypic abnormalities seen, several potentially site -specific abnormalities such as deletions of chromosome 3p, 7q and 3q, and amplifications of 3p, 7q, 1q, 11p, 2p and 12p in 6 SCLC cell lines established from chemotherapy resistant patients tumor cells. Losses of short arm chromosome 11 and 12 (11p, 12p) and long arm of chromosome 13 (13q), and amplifications of chromosomes 2, 11, 12, 13 and 19 (2p, 11p, 12p, 13q, 19p) were recurrently identified in the several cell lines, being different from published chromosomal abnormalities in American SCLC, which suggests geographical difference of SCLC karyotype. Also, these abnormal patters were largely different from non-small cell lung carcinoma (NSCLC). Unknown oncogenes localizing on these chromosome breakpoints for translocation or deletion region might be associated with the pathogenesis of SCLC. Present analysis can provide information on significant genes involved pathogenesis of SCLC.