Characterisation of the p53 status, BCL-2 expression and radiation and platinum drug sensitivity of a panel of human ovarian cancer cell lines.

The P53 gene is frequently mutated in late stage ovarian cancer and has been proposed as a determinant of radiation and chemosensitivity. We have therefore determined the p53 functional status, P53 sequence, radiation sensitivity and cytotoxicity of cisplatin and the novel platinum analogue, AMD473, in a panel of 6 human ovarian cancer cell lines. Constitutive p53 protein levels were low in A2780, CH1, LK1, LK2 and PA1 but were markedly induced following irradiation. In OV1P, constitutive p53 protein was readily detectable and levels were induced slightly following irradiation. p21WAF1/CIP1 and MDM-2 mRNA were constitutively expressed in all the cell lines and expression was induced markedly following irradiation. There was marked radiation induced G1/S arrest in A2780 but only partial arrests in CH1, LK1, LK2, PA1 and OV1P lines. No mutations were found in A2780, CH1, LK1, LK2 and PA1 cells by single-strand conformational polymorphism (SSCP) analysis but a heterozygous point mutation was found in exon 5 of OV1P. All the cell lines were radiation sensitive and also relatively sensitive to cisplatin; however, OV1P was the most resistant being consistent with its heterozygous P53 status. AMD473 was less potent than cisplatin but a similar pattern of drug sensitivity was observed with the exception of LK2, which was resistant. CH1, LK1, LK2 and PA1 all expressed BCL-2 protein but there was no expression in A2780 and OV1P. Our results suggest an overall association between wild type P53 and radiation and platinum drug sensitivity in these ovarian cancer cell lines.