Study On The Anti-cancer Effect Of Isorhmnetin And Its Mechanism Of Action

Objective:To study the inhibiting effect of isorhmnetin on human cervical cancer, tongue squamous epithelium cancer, Lung cancer and esophageal tumor cells, and to elucidate the molecular mechanisms of this compound inhibiting cancer cells.Methods and Resultes:1. Inhibiting growth in cancer cells were measured by microculture tetrazolium assay, growth curve, clone formation test and 3H-thymidine uptake assay, observed and analyzed by light microscopy, electronic microscopy, agarose gel electrophoresis, cell cycle analyzed by flow cytometry. Results: The growth of cancer cells were inhibited evidently after treated by isorhmnetin, the growth inhibition of cancer cells versus the concentration of isorhmnetin exhibited a dose-response and time-response relationship. The cells showed characters of apoptsis and differentiation observed by light and electronic microscopy, agarose gel electrophoresis of DNA showed change of "Ladder" pattern. The rates of apoptosis increased after treated with isorhmnetin, and the cell was inhibited in G0/G1 phase, the cellular number in S phase decreased (P<0.05).2.The telomerase activities of HeLa,Tca-8113,YTLMC-90 and Eca-109 cells in vivro were investigated by TRAP-ELIAS technique.The catalase activities of cancer cells were analyzed with UV-visible Recording Spectrophotometer. The expressions of genes were analyzed by flow cytometry. The expression of PCNA was detected by immunohistochemical method. The expression of Id-1 were inspected by flow cytometry and immunofluorescence method. Results: The telomerase and catalase activities of cancer were inhibited when treated with isorhmnetin compared to the negative control. Isorhmnetin decreased the expression of bcl-2, c-myc, H-ras oncogene and increased the expression of bax, c-fos and p53. The expression of PCNA and Id-1 were lower than the negative control group after treated with isorhmnetin.3.To investigate the effect of isorhmnetin on tumor growth, cell proliferation and apoptosis in transplantation rumor of lung cancer of Lewis cell line in C57BL/6 mice. Lewis cells were inoculated into the the C57BL/6 mice to establish Lewis lung cancer model, then fifty six C57B1/6 mice with Lewis tumor were randomized four groups: control group, isorhmnetin group, treated in advanced with isorhmnetin group, cisplatin group. After 7 days treatment,samples of tumor were collected. The sections of tumor were observed under light microscope and electron microscope. The expression of PCNA, bcl-2 and bax were detected by immunohistochemistry. We found that, the tumor weight of control group was significally higher than those treated with medicines; immunohistochemical stainng of PCNA showed that the PCNA lable index displayed significally defference between negative control group and medicine groups, the expression of PCNA of medicine groups lower than that of negative control, and so did the staining of bcl-2; but the expression of bax of medicine groups higher than that of control group (P<0.05). 4. The circadian rhythms of DNA synthesis and the expression of c-myc gene in untreated and treated Eca-109 cells in human esophageal cancer with isorhmnetin were studied. The circadian rhythms of 3H-TdR incorporation and expression of c-myc gene in untreated and treated Eca-109 cells was measured by 3H-thymidine uptake assay and flow cytometry. Dates were documented by ANOVA and Cosinor analysis. The results showed that DNA synthesis and expression of c-myc gene in untreated group varied according to circadian time with statistical significance, the distribution curves of both DNA synthesis and the expression level of c-myc were fit for cosinor changes. The circadian rhythms of DNA synthesis and circadian parameters of c-myc expression in treated Eca-109 cells changed. The circadian parameters of DNA synthesis and expression level of c-myc were varied after treating by isorhmnetin. Conclusion:The results once more confirmed that isorhmnetin can inhibit growth, proliferation and induce differentiation of Hela, Tca-8113, YTLMC-90 and Eca-109 cells. The mechani...