CDKN2 IN HPV-POSITIVE AND HPV-NEGATIVE CERVICAL-CARCINOMA CELL-LINES

Human cervical cancers frequently contain retinoblastoma protein (Rb) that is inactivated by binding with human papilloma virus (HPV) E7 pro tein or through mutation. The CDKN2 gene encodes p16(INKA) which inhib its cdk4-cyclin D phosphorylation of Rb, preventing the G(1)-S transit ion. To determine whether abnormalities of CDKN2 occur in cervical-can cer cells, II cervical cell lines, including 8 HPV-positive cell lines , 2 HPV-negative cell lines containing mutant Rb, and one tumorigenic cell line derived from normal cervical cells following transfection wi th HPV-16 and v-H-ros (CX16-2HR), were analyzed. No cell line had a ho mozygous deletion of exon I or 2 of CDKN2, and only one cell line, CX1 6-2HR, had an altered DNA sequence, which represents a common polymorp hism at codon 148. To exclude the possibility of other subtle inactiva ting mutations, immunoblot analysis of protein lysates was performed u sing a polyclonal anti-p16(INKA) rabbit anti-serum. Abundant levels of normal-sized p16(INKA) were observed in all cell samples. Thus, no al terations of CDKN2 were detected in these cervical cell lines. These r esults confirm that mutational inactivation of p16(INKA) is a rare eve nt in tumor samples with compromised Rb activity. (C) 1995 Wiley-Liss, Inc.