OBJECTIVETo study effects of hypericin associated with light irradiation on human laryngeal squamous cell carcinoma strain Hep-2.

METHODSUsing techniques of tumor cells culture in vitro, Hep-2 cells were exposed to different concentration hypericin as 0.5, 1.0, 2.0, 3.0, 5.0 microg/ml, then 10 minutes 7.5 J/cm2 light irradiation was given after an hour. Other groups Hep-2 culture cells were also exposed to different concentration hypericin as 5.0, 10.0, 20.0, 25.0 microg/ml, without light irradiation. In all groups, contrast groups were set up. And 48 hours later, growth characteristics of Hep-2 cells were studied by morphological observation, fluorescence microscope, MTT assay and flow cytometry.

RESULTSIn normal contrast group, Hep-2 cells grew intensively and contacted with each other. However, cells which were treated with hypericin, combination with light irradiation were declined greatly. In higher dose hypericin group, necrosis could be found. MTT assay showed that hypericin associated with light irradiation inhibited growth of laryngeal cell with dose dependence manner. Flow cytometry showed that hypericin with light irradiation could block cell growth at G0/G1 phase, inducing apoptosis of laryngeal cell. Under fluorescence microscope, some sings of cell apoptosis including coagulation of chromatin, fragmentation of nuclei and apoptotic body could be found.

CONCLUSIONHuman laryngeal squamous cell carcinoma strain Hep-2 can be inhibited and induced into apoptosis by treated with hypericin combination with light irradiation.