Anti-tumor Effect Of Anisomycin On CT26-bearing Mice And Its Mechanism

Background: It is reported that anisomycin can induce apoptosis to varies of cells in vitro,and our previous study of anisomycin’s effect on EAC and B16tumor in vivo showed thatanisomycin can significantly lengthen survive time of tumor-bearing mouse with its inhibitioneffect on tumor growth. There is no report about the in vivo anti-tumor effect of anisomycin onother different organs and tissues so far. Obviously, further study of the possibility of anisomycinon digestive system tumor therapy may be of significance, and provide experimental basis for itsclinical application.Aim: To observe the in vivo anti-tumor efficacy of anisomycinon CT26murine coloncarcinoma and to investigate the preliminary anti-tumor mechanism of anisomycin in vitro and invivo.Methods: In vitro model of CT26cell line was built for study. MTT assay was employed todetect the effect of ansomycin on CT26cell; Flow cytometry was applied to investigate the cellcycle changes and apoptosis of CT26cells induced by anisomycin; the apoptosis related proteinswere determined by western blotting. In vivo model of CT26solid tumor model was built onBalb/c mouse, drug treatment was carried out by intratumoral injection of5mg/ml anisomycinor adriamycin, and tumor growth, tumor-bearing mouse survival rate and changes of immuneorgans were observed, TUNEL and flow cytometry were carried out to observe the apoptosis ofcells in tumor tissues. Apoptosis related proteins of tumor tissues were also checked by westernblotting. Observation of lymphocyte infiltration was performed after HE staining. ELISA wasalso employed to detect the related cytokine content in serum from CT26-bearing mice. Tumormarker CEA was detected with IHC assay.Result: Anisomycin significantly inhibited CT26cells’ proliferation with the most significantinhibition at48hours and72hours. The cells increasingly accumulated in Sub-G0/G1and fewercells stepped into G0/G1phase, and late-phase apoptosis cells increased as well. The levels of caspase-3, cleaved caspase-3, cleaved caspase-8and cleaved caspase-9were also up-regulatedwith the increasing drug concentration. The tumor volume in the drugs treated groups was bothsmaller than in the control one, while mice in adriamycin treated group lived significantly shorterthan anisomycin treated one(P<0.05); In anisomycin group, spleen index was lower and thymusindex was higher than that of the untreated group. The cell apoptosis proportion of the tumortissue in anisomycin group was significantly more than those in adriamycin group and untreatedgroup with the higher level of apoptosis proteins than other groups. IHC result showed thattumor marker CEA expression in anisomycin group and adriamycin group appeared lower thanin the untreated group. ELISA showed that there was a lower concentration of INF-γ, TNF-αandTGF-βin the both treated groups.Conclusion：The present study shows that anisomycin can significantly inhibit CT26tumorgrowth and prolong the survival time of the tumor-bearing mice. The probable anti-CT26tumormechanism of anisomycin is related to the inhibition of CT26cell proliferation and cell cycleand the induction of CT26cell apoptosis by up-regulating and activating caspase proteins withthe reduction of CEA expression.