Alteration in TWIST expression: possible role in paclitaxel-induced apoptosis in human laryngeal carcinoma Hep-2 cell line.

AIM: To explore the relationship between alteration in the expression of TWIST, highly conserved transcription factor from the basic helix-loop-helix family, and apoptosis of Hep-2 cells induced by chemotherapeutic agent paclitaxel. METHODS: Morphological changes of Hep-2 cells were observed by acridine orange cytochemistry staining. Viability of Hep-2 cells treated with various concentrations of paclitaxel was examined by cell proliferation assay. Apoptosis was examined by flow cytometry. The mRNA and protein expression of TWIST in response to paclitaxel at 24 hours, 48 hours, and 72 hours was examined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. RESULTS: Typical morphological changes of apoptotic cells at 24 hours, 48 hours, or 72 hours after treatment wiyth paclitaxel (10x10(-9) mol/L) were observed. The cell survival rates significantly decreased in a concentration- and time-dependent manner (P=0.001). Paclitaxel-induced apoptosis increased with culture time (22.6+/-5.3% after 24 hours, 38.7+/-7.9% after 48 hours, and 52.4+/-14.3% after 72 hours; P=0.002). Both mRNA and protein expression of TWIST was markedly decreased at both mRNA levels and protein levels, at 24 hours, 48 hours, and 72 hours in the paclitaxel-induced apoptosis of Hep-2 cells (P<0.001). CONCLUSION: TWIST, which has a significantly decreased expression in response to paclitaxel in Hep-2 cells, may play a pivotal role in paclitaxel-induced apoptosis of Hep-2 cells.