Study On The Anti-tumor Activities And Mechanisms Of A Novel Camptothecin Compounds, ZH-001

Objectives: To evaluate the anti-tumor activity of a novel camptothecin compound ZH-001 in vitro and in vivo.To explore possible mechanisms by which ZH-001 induced cytotoxicity and tumor growth suppression.Methods: 1.Anti-tumor activity of ZH-001 in vitro and in vivo: 1)MTT assay and SRB assay were applied to evaluate the potent cytotoxicity against 20 different human cancer cell lines and calculate the IC50 value.2)Colo205,HCT-116,SW-620 and NCI-H460 xenografted athymic mice models were established to evaluate anti-tumor activity of ZH-001 in vivo.2.The anti-tumor mechanism of ZH-001: 1)The effect of ZH-001 on Topoisomerase ? activity was examined using agarose gel electrophoresis.2)HCT-116 cells were treated with concentration gradient of ZH-001.Flow cytometry analysis was performed to determinecell cycle distribution by using PI staining.3)Western blotting assay was conducted to validate the expression of the proteins relating to cell cycle,apoptosis and ?-H2 AX in HCT-116 cell.Results: 1.ZH-001 exhibited broad anti-tumor spectrum in vitro and effective anti-tumor activity in vivo: 1)Cytotoxicity assay demonstrated that ZH-001 was a high efficient anti-tumor compound in 20 different cell lines with average IC50 value of 3.46-259.76 n M.The average IC50 value of two positive drugs,TPT and SN-38,were 11.34-1814.42 n M and 6.05-1169.66 n M,respectively.2)In Colo205 xenograft model,ZH-001 1.6 mg/kg had the same therapeutic effect as the positive drug CPT-11 2.5 mg/kg.In HCT-116 and SW-620 xenograft models,minimum effective dose of ZH-001 was 0.8 mg/kg,which was less than the positive drugs.In NCI-H460 xenograft model,ZH-001 perform dose-dependent inhibition to tumor growth but less effective than the positive drugs.2.ZH-001 could inhibit Topoisomerase ? activity,induce DNA damage,lead to cell cycle arrest and apoptosis,and ultimately play an anti-proliferation activity: 1)ZH-001 could intervene the activation of Topoisomerase ? and reduce DNA supercoiling release,the effect is similar to SN-38,but more apparent than TPT.2)Western blotting assay showed an accumulate effect on ?-H2 AX,suggesting an occurrence ofDNA damage,which had no cognitive difference comparing to TPT and SN-38.3)Cell cycle G2/M phase arrest was observed in a time-dependent manner,which was more effective than TPT but equivalent to SN-38.Moreover,the expression of cell cycle related proteins like CDK1 and Cyclin B1 declined in ZH-001-treated HCT-116 cells.4)ZH-001 could increase the expression of pro-apoptotic protein Bax,reduce the expression of anti-apoptotic protein Bcl-2,but the effect of promoting the down-regulation of pro-Caspase-3 was less than that of the positive control SN-38.Conclusion: ZH-001 has a board anti-tumor spectrum in vitro and in vivo,and performs more effective than SN-38 and TPT.ZH-001 exerts anti-tumor activity through restraining Topoisomerase ? activity,inducing DNA damage,leading to cell cycle arrest and apoptosis.Our results suggest that ZH-001 is a novel,high efficient camptothecin compound.It may have the good prospects for further development.