Alterations in the tumor suppressor genes p53, RB, p16/MTS1, and p15/MTS2 in human pancreatic cancer and hepatoma cell lines

The tumor suppressor genes p53, retinoblastoma (RB), p16, and p15 encode proteins that regulate the cell cycle cooperatively by controlling the transition from G1 to S phase and may play an important role in cell growth and differentiation. To screen for abnormalities in these genes in cancer, we performed genetic analysis in six human pancreatic cancer and five hepatoma cell lines, by single-strand conformation polymorphism (SSCP) analysis, direct sequencing, and the reverse transcriptase-polymerase chain reaction (RT-PCR). All six pancreatic cancer cell lines had p53 mutations, with the concomitant loss of the other normal allele, encoding wild-type p53. Frequent homozygous deletions were found in p16 and p15, but the RB gene was expressed. Four of the five hepatoma cell lines had p53 mutations with loss of the normal allele and aberrant RB. There were no deletions of p16 and p15 in any of the hepatoma cell lines. These findings suggest that alterations in the p53, p16, and p15 genes are common in human pancreatic cancer cell lines, while p53 or RB mutations are common in hepatoma cell lines. Alterations of these tumor suppressor genes may thus be important features in organ-specific carcinogenesis.