Study On Anticancer Effect Of Two Novel Topoisomerase Inhibitors And Their Mechanisms

Aim: To investigate the anticancer effect of 6-methyl-11-(N, N-dimethyl-4- vinylbenzenamine)-7,8,9,10-tetrahydro-1H-indolo[1, 2-b]indazole trifluoromethylsulfonate (Compound 1) and 4-((Z)-(5H- 1-methyl-indeno[1, 2-b]pyridine-5-ylidene)methyl)-N, N- dimethylbezenamine trifluoromethylsulfonate (Compound 2) in vitro and their mechanism.Methods: The proliferative inhibitions of 9 human tumor cell lines induced by Compound 1 or Compound 2 were assessed with MTT assay. The effects of compounds on TopoⅠmediated-pBR322 DNA unwinding were measured by using agarose gel electrophoresis, the protein expression of TopoⅠ/Ⅱin HEp-2 cells was evaluated by western-blot analysis. The activation of proapoptotic effect and cell cycle arrest of HEp-2 cells were characterized by Hoechst stain, AO stain, single cell gel electrophoresis and flow cytometry. Western blot analysis was used to study the mechanism in Compound-induced death of HEp-2 cells.Results: MTT assay indicated that Compound 1 and Compound 2 decreased the viability of 9 human tumor cell lines in dose- and time-dependent; Compound 1 and Compound 2 inhibited the TopoⅠ-mediated relaxation of supercoiled pBR322 plasmid DNA effectively. The results of western blot assay indicated that the compounds could decrease the TopoⅠ/Ⅱprotein expression in cells; Apoptosis was induced in HEp-2 cells by the compounds as detected by Hoechst staining and AO staining; DNA damage induced by the compounds was detected by single cell gel electrophoresis; flow cytometry analysis indicated that the compounds increased cell population at sub-G1 phase, an index of apoptosis, S and G2/M cell arrest (induced by Compound 1) and G1 cell arrest (induced by Compound 2); western blot analysis indicated that the compounds increase Bid, Bax and JNK expression, decrease Bcl-2, cyclin B1 and cyclin D1.Conclusions: Together, these findings indicated that 6-methyl-11-(N, N-dimethyl-4- vinylbenzenamine)-7, 8, 9, 10-tetrahydro-1H-indolo[1,2-b]indazole trifluoromethylsulfonate and 4-((Z)-(5H-1-methyl-indeno1,2-b]pyridine-5-ylidene)methyl)-N,N-dimethylbezenamine trifluoromethylsulfonate induced the proliferation inhibition, their mechanism are probably related to these factors as follow:①Inhibition of catalytic activity of TopoⅠand down-regulation of TopoⅠ/Ⅱprotein expression in cells;②By regulating transcription and expression of tumor related genes to induce apoptosis;③The cell cycle arrest which improved the apoptosis of the cells.