Mutational analysis of the beta-tubulin gene in lung cancer.

Recently, several studies have suggested that a major mechanism of resistance to paclitaxel might involve mutations in the beta-tubulin gene in tumor cells. To investigate the frequency of beta-tubulin mutations in Japanese patients with small and non-small cell lung cancer, direct sequence analysis following reverse transcription-polymerase chain reaction (RT-PCR) of the beta-tubulin gene was performed using total RNA from 20 lung cancer cell lines and 22 specimens from lung cancer patients. First-strand cDNA sequence analysis of the 42 samples showed silent mutations at codon 180 of the beta-tubulin gene, which encodes the GTP-binding site of the protein, and codons 195 and 217. However, neither missense nor non-sense mutations affecting microtubule dynamics, within or near the GTP-binding site of the beta-tubulin gene, were detected. These results indicate that beta-tubulin gene mutations might not play a major role in the mechanism of resistance to paclitaxel in Japanese lung cancer patients. Further investigations are needed to clarify the mechanism of drug resistance.