DMH1 (4-[6-(4-isopropoxyphenyl)pyrazolo[1,5-a]pyrimidin-3-yl]quinoline) inhibits chemotherapeutic drug-induced autophagy

Our previous work found that DMH1 (4-[6-(4-isopropoxyphenyl)pyrazolo [1,5-a]pyrimidin-3-yl]quinoline) was a novel autophagy inhibitor. Here, we aimed to investigate the effects of DMH1 on chemotherapeutic drug-induced autophagy as well as the efficacy of chemotherapeutic drugs in different cancer cells. We found that DMH1 inhibited tamoxifen- and cispcis-diaminedichloroplatinum (II) (CDDP)-induced autophagy responses in MCF-7 and HeLa cells, and potentiated the anti-tumor activity of tamoxifen and CDDP for both cells. DMH1 inhibited 5-fluorouracil (5-FU)-induced autophagy responses in MCF-7 and HeLa cells, but did not affect the anti-tumor activity of 5-FU for these two cell lines. DMH1 itself did not induce cell death in MCF-7 and HeLa cells, but inhibited the proliferation of these cells. In conclusion, DMH1 inhibits chemotherapeutic drug-induced autophagy response and the enhancement of efficacy of chemotherapeutic drugs by DMH1 is dependent on the cell sensitivity to drugs.