A Study On The Effect And Mechanism Of Artemisinin And Artemether On The Radiosensitivity Of Human CNE-1 Nasopharyngeal Carcinoma Cell

Objective :The research projects is to investigate the effect and mechanism of artemisinin and artemether on radiosensitivity of p53 CNE-1 nasopharyngeal carcinoma cells. To determine the proper concentration and action time of artemisinin and artemether used in radiosensitising study by studing the inhibition effect of artemisinin and artemether onCNE-1 cells with change of the concentration and action time. To discuss the effect of To discuss the effect of artemisinin and artemether on the radiosensitivity of cells by the studing effect of artemisinin and artemether on proliferation capacity of CNE-1 cells after radiate. To discuss the mechanism of radiosensitising of artemisinin and artemether by the studing effect of artemisinin and artemether combined with 60Coγray on cell cycle and expression of cell cycle regulatory protein wee1, cyclinB1.Methods: (1) The effect of artemisinin and artemether on survival fraction of nasopharyngeal carcinoma cells was assessed by MTT assay . (2) The effect of artemisinin and artemether on radiosensitization on the cells was assessed by colony formation .(3) Study the effect to CNE-1 cells by artemisinin and artemether combined with 60Co-γby using cytokinesis block method(CB method) micronucleus method and conventional chromosome examination; (4) The changes of cell cycle distribution effected by artemisinin and artemether combined with 60Co-γirradiation was detected by flow cytometry . (5) Change of expression of cycle regulatory protein wee1 , cyclinB1 caused by artemisinin and artemether combined with 60Co-γirradiation was investigated by Western blot .Results: (1)MTT analysis showed that The inhibition of artemisinin and artemether on human CNE-1 cells of were in concentration-dependent and time-depentent manners.(2) Inhibition rate of artemisinin and artemether to CNE-1 cells was different, when inhibition rate of artemisinin and artemether to CNE-1cells both reached about 10%, drug concentration was 5μmol/L and 20μmol/L respectively. (3) With the same dose of radiation, clone formation rate decreased with the increase of concentration of artemisinin and artemether. With the same drug concentration, clone formation rate decreased with the increase of radiation dose. Artemether on the CNE-1 cell toxicity is lower than artemisinin. the radiosensitizing of artemether is more obvious in CNE-1 cells. As to CNE-1 cells , in radiation group and artemisinin plus radiation group, the mean lethal dose (D0) was 5.6Gy and 4.4Gy respectively, and the quasi-threshold dose (Dq) was 1.33Gy and0.285Gy respectively, so SER was 1.272 . in radiation group and artemether plus radiation group, the mean lethal dose (D0) was 5.6Gy and 3.7Gy respectively, the quasi-threshold dose (Dq) was 1.33Gy and0.25Gy respectively, so SER was 1.481. (3)micronucleus and chromosome analysis showed that: chromosome damage of CNE-1 cells treated with artemisinin and artemether united with irradiation of the same dose is more serious than treated only with radiation; (5) Compared with radiation group, in CNE-1 cells , the percent of cells in G1 phase increased and G2 phase decreased in the radiation combined with drug group , and apoptosis also increased. (6)Western blot result showed that, compared with radiation group , in CNE-1 cells , expression of wee1 decreased and cyclinB1 increased.Conclusions: (1) artemisinin and artemether are hypo-cytotoxic drugs to the CNE-1 cells of human nasopharyngeal carcinoma and its'inhibition rate of these cells is increased with the rising concentration and prolonging time of action; (2) The inhibition rate of CNE- cells is different between the artemisinin and artemether with the same dose and artemisinin's inhibition rate of CNE-1 cells is higher than that of artemether's. (3) Artemisinin and artemether could have radiosensistivity of CNE-1 cells with mutant type P53 gene proteis stronger than that of artemisinin. (4) The damage degree of chromosome under the action of artemisinin and artemether combined with the same dose irradiation is more serious than by the single irradiation. (5) the radiosensitizing effects of artemisinin and artemether on CNE-1 cells are associated with the inhibiting of induction and activation of the blockade effect, caused by irradiation, on stage G2/M, in on human nasopharyngeal carcinoma and the radiosensisitive action of artemether which lead the damaged cells into death for they entered the division straight without being repaired. (6)the radiosensitizing effects of artemisinin or artemether in combination with irradiation on CNE-1 cells is via the inducing low expression of wee1 proteins, high expression of cyclin B 1 proteins, which could weaken the blockage effects on stage G2/M caused by the irradiation.Artemisinin and artemether have certain radiosensitizing effects in CNE-1 cells of human nasopharyngeal carcinoma and the action of artemether is stronger than that of artemisinin. Their mechanism is related to the changing cell cycle distribution, inducing the cell blocked at the radiosensitive stage G2 and inhibiting sub-lethal reparation of cells.