[Cisplatin-induced apoptosis in laryngeal squamous cell carcinoma strain and the influence on cell cycle]

To find more effective chemotherapeutic agents and treatment regimens, we studied the cytotoxicity of cisplatin to human laryngeal squamous cell carcinoma strain Hep2.

Using flow cytometry, fluorescence microscopy, and DNA agarose gel electrophoresis technique, we investigated in vitro Hep2 cells in different conditions.

Hep2 was adherent cells in normal survival condition. Cisplatin affected Hep2 cell growth apparently. Under fluorescence microscope, necrotic cells were red, apoptotic cells were blue with condensed and fragmented nuclei, and normal cells were evenly blue. Adherent cells were 86%-96% viable. But nonadherent cells were 6%-13% viable. Death cells increased with the increase of drug concentration and time elapsing. Death cells were mainly apoptotic cells. The latter appeared to be time- and dose-dependent. DNA "ladder" was observed for nonadherent cells in agarose gel electrophoresis, but adherent cells were not. "Sub-G1" phase peak occurred in flow cytometry. After cisplatin treatment, the volume of adherent cells increased with dose- and time dependence. Cisplatin could cause Hep2 cell cycle to change. At first, G1 phase cell percentage reduced, while S phase increased. With time elapsing, G2/M phase increased. Cells experienced a slow-down in S-phase followed by a G2 block.

Apoptosis is a major way of Hep2 cell death after cisplatin treatment and appeared to be time- and dose-dependent. In clinical chemotherapy, cisplatin should be used in high concentration. Inducing apoptosis is one of the characteristics of chemotherapeutic agents. Cisplatin should be taken a combination regimen with cell cycle-special agents.