3-chloromethylene-6-fluorthiochroman-4-one,A Novel DNA Topoisomerase Poison

CMFT has a strong antitumor activity which was synthesized from Hebei university college of pharmacy.It is of great significance to discuss the new compound of anti-tumor mechanism.In this paper,we will compare the antitumor activity of the cis-trans isomers,and explore their inhibiting effects on human topoisomerase I and topoisomerase II in cell free reaction system.The MTT method was used to study inhibition rates;the AO/EB double staining and TUNEL assay was used to assess proportion of apoptotic cells.The inhibition of CMFT to Top I and II could be identified by adding CMFT solutions to Top-DNA reaction mixtures and observing the relative quantities of relaxed strands and supercoils in electrophoresis assay.In vivo,the portability tumors model is used to detect antitumor effect.At the end of the experiment,by spinning off tumor,spleen and thymus of mice,the tumor inhibitory,rate the spleen index and thymus index is calculated after weighing.Results showed that CMFT had dramatic anti-tumor activities at low concentrations and the activity of CMFT trans-isomer is more significant.Use of AO/EB double staining and TUNEL indicated that CMFT induces apoptosis.Cell cycle distribution analysis indicated that there was a concentration-dependent increase in the number of cells in S-phase.Concomitantly,there was a decrease in the number of cells in G1-phase and no significant change in G2/M-phase.These results suggest that CMFT disturbs cell cycle progression,leading to the accumulation of cells in S-phase.DNA relaxation assays and DNA cleavage and relegation assays were performed and showed a higher potential to interact with topoisomerase I(Top I)and topoisomerase II(Top II)and it was verified that CMFT is a Top poison which could be one of the mechanisms that induce cell apoptosis.Our results provide preliminary data for further investigation for the mechanism of CMFT of the apoptotic mechanism.