日蟾蜍它灵通过HSP90/突变p53途径抑制三阴性乳腺癌细胞增殖

Gamabufotalin Inhibits the Proliferation of Triple Negative Breast Cancer Cells Through HSP90/mutant p53 Pathway

三阴性乳腺癌(triple negative breast cancer,TNBC)恶性程度高,预后差,其p53基因的突变频率达80%以上。日蟾蜍它灵(gamabufotalin,CS-6)是日本蟾蜍的皮肤分泌物,有研究表明CS-6具有抗癌作用,但其对TNBC的作用和机制尚无报道。本文采用MTT法和细胞克隆形成实验检测了不同浓度CS-6对TNBC细胞系MDA-MB-468和MDA-MB-231细胞增殖的影响;采用Western-blot检测了CS-6在外源和内源水平对p53和热休克蛋白90(heat shock protein 90,HSP90)表达水平的影响;采用联合指数及等效线分析法考察了CS-6和HSP90的抑制剂坦螺旋霉素(tanespimycin,17-AAG)对MDA-MB-468和MDA-MB-231细胞增殖的协同作用。结果显示,CS-6明显抑制MDA-MB-468和MDA-MB-231细胞的增殖,其抑制增殖机制有可能与降解HSP90/突变p53有关;而且,CS-6和HSP90抑制剂17-AAG联合用药对抑制MDA-MB-468和MDA-MB-231细胞增殖具有协同作用。

Triple negative breast cancer(TNBC)is a highly malignant tumor with a poor prognosis,and the mutation frequency of p53 gene in TNBC patients is more than 80%.Gamabufotalin(CS-6),a skin secretion from Japanese common toad(Bufo japonicus),has been shown to have anticancer effects.However,the role and underlying mechanism of CS-6 against TNBC have not been reported.Herein,the effects of different concentrations of CS-6 on the proliferation of TNBC cell lines MDA-MB-468 and MDA-MB-231 were detected by MTT assay and clone formation assay.The effects of CS-6 on the expression of p53 and heat shock protein 90(HSP90)at exogenous and endogenous levels were detected by Western-blot.The synergistic effect of CS-6 and the HSP90 inhibitor tanespimycin(17-AAG)on the proliferation of MDA-MB-468 and MDA-MB-231 cells was investigated by combination index and equivalent linearization analysis.The results showed that CS-6 significantly inhibited the proliferation of MDA-MB-468 and MDA-MB-231 cells.The mechanism of inhibition of the tumor cell proliferation may be related to degradation of HSP90/mutant p53 protein.In addition,CS-6 and HSP90 inhibitor 17-AAG had a synergistic inhibitory effect on the proliferation of MDA-MB-468 and MDA-MB-231 cells.