Semi-quantitative analysis of DNA topoisomerase-I mRNA level using reverse transcription-polymerase chain reaction in cancer cell lines: its relation to cytotoxicity against camptothecin derivative.

Expression of DNA topoisomerase (Topo)-I-mRNA in various cancer cell lines was detected using the reverse transcription-polymerase chain reaction (RT-PCR) method. The cytoplasmic polyadenylated RNA isolated from cancer cell lines was reverse-transcribed and the complementary DNA was amplified by PCR primed with Topo-I specific primers. Fidelity of the amplified sequence was confirmed by restriction endonuclease digestion and Southern blot hybridization. The level of Topo-I mRNA was correlated positively with the cytotoxicity of a Topo-I inhibitor, a camptothecin derivative. This RT-PCR method may be applicable to the assessment of sensitivity of cells to Topo-I targeted drugs, especially when only small quantities of cell samples are available.