Cellular sensitivity determinants to docetaxel in human gastrointestinal cancers.

beta-tubulin (beta-TUB), Bcl-XL, and additionally glutathione S-transferase pi (GSTpi) were found to participate in sensitivity to docetaxel (TXT) in 7 human gastrointestinal cancer cell lines. The gene expression level of beta-TUB, Bcl-XL, and GSTpi was closely correlated with the IC50 for TXT. beta-TUB amount related to TXT resistance, and GST activity was correlated with IC50 for TXT in the 30-min treatment setting. Bcl-XL transfection increased TXT resistance of COLO201 cells, whereas GST inhibition by ethacrynic acid enhanced TXT cytotoxicity. Continuous TXT treatment increased beta-TUB and GSTpi expression, but the increased GSTpi mRNA was observed in TXT-resistant HCC-48 cells alone.