ANALYSIS OF THE RB GENE AND CYCLIN-DEPENDENT KINASE-4 INHIBITOR GENES(P16(INK4) AND P15(INK4B)) IN HUMAN OVARIAN-CARCINOMA CELL-LINES

In the present study, we analyzed human ovarian carcinoma cell lines f or abnormalities in the tumor suppressor gene Rb (retinoblastoma) and in cyclin-dependent kinase 4 (CDK4) inhibitor genes (p16(LNK4) and p15 (INK4B)) using molecular biology techniques. For the Rb gene, in all s ix cell lines (PA-1, Caov-3 and -4, OVCAR-3, SK-OV-3, and Kuramochi), Rb gene abnormality was not detected using Southern blotting. In the C aov-3 cell line transcripts were not detectable by either Northern blo t or polymerase chain reaction. Sequence analysis of the entire coding region of the Rb gene revealed point mutations (AAC to GAG) resulting in codon 123 (Asn to Asp) changes in the Caov-4 cell line. In the PA- 1 cell line both wild-type Rb and mutant-type Rb (codon 798: CGG to TG G) were expressed, and in the OVCAR-3 cell line both wild-type Rb and mutant-type Rb (codon 704: ATG; to GTG) were expressed. In four of six human ovarian carcinoma cell lines Rb gene abnormality was detected. For the p16(INK4) and p15(INK4B) genes, only the SK-OV-3 cell line had abnormalities. There was a gene rearrangement or minor deletion of th e p16(INK4) gene in the SK-OV-3 cell line, while the p15(INK4B) gene w as deleted in this cell line. In the SK-OV-3 cell line no mRNAs of p16 (INK4) and p15(INK4B) were expressed. At the point of Rb gene inactiva tion, we can explain five cell lines of six: four cell lines had abnor malities in the Rb gene itself, which is another mechanism by which th e Rb gene is inactivated, while one cell line (SK-OV-3) had abnormalit ies in CDK4 inhibitor genes, another of the inactivation mechanisms of the Rb gene. These data suggest that abnormalities of Rb and CDK4 inh ibitor genes (p16(INK4), p15(INK4B)) may be involved in human ovarian carcinogenesis. (C) 1997 Academic Press.