Combined effect of docetaxel and cisplatin for non-small cell lung cancer cell lines in vitro.

Docetaxel (DOC) plus cisplatin (CDDP) is a novel combination chemotherapy for the treatment of advanced non-small-cell lung cancer (NSCLC). We investigated the combined effect of DOC with CDDP in sequence and the reverse schedule for NSCLC cell lines EBC-1 (squamous cell carcinoma) and RERF-LC-MS (adenocarcinoma) using an MTT assay and an improved isobologram method. The results showed that the combination of DOC and CDDP in human lung cancer cell lines was antagonistic. To investigate the possible mechanism of the antagonistic effect, we focused on the cell cycle perturbation and the inhibition of apoptosis fractions induced by chemotherapeutic agents. Pretreatment of CDDP significantly blocked the following DOC-induced apoptosis fraction. Therefore we consider that the suppression of apoptosis could be one of the mechanisms for antagonistic effects of combination chemotherapy of DOC and CDDP.