The effect of co-treatment with DAPT and oxaliplatin on the biological behavior of human ovarian cancer stem cells

Abstract To assess the effects of the combination of DAPT and oxaliplatin on the biological behavior of human ovarian cancer stem cells. In vitro cultured human ovarian cancer stem cells were randomly divided into DAPT, L-OHP, DAPT + L-OHP, and control groups. MTT assays were measured to assess the ability of inhibit proliferation. Inverted microscopy, flow cytometry, and in vitro invasion assays were performed to assess cell morphology, apoptosis, and cell invasion, respectively. Then, western blotting was used to detect Notch-1 and LRP1 expression in the four groups of cells. MTT assay revealed that DAPT and L-OHP monotherapy could inhibit the proliferation of ovarian cancer stem cells in a time- and dose-dependent manner. Inverted microscopy showed that untreated ovarian cancer stem cells had an oval or polygonal morphology, with a plump shape and large nuclei. After treatment with DAPT or L-OHP, cells shrank and cracked, with an irregular shape and increased shedding. Flow cytometry revealed that apoptosis was significantly higher in the DAPT and L-OHP groups compared with the control group; the DAPT + L-OHP group had a significantly higher rate of apoptosis than either the DAPT or L-OHP groups. An in vitro invasion assay revealed that DAPT + L-OHP inhibited cell invasion to a greater extent than either DAPT or L-OHP alone. Western blotting revealed that, compared with control, L-OHP had no effect on Notch-1 protein expression, whereas DAPT and DAPT + L-OHP significantly reduced Notch1 protein levels. In addition, cells treated with DAPT + L-OHP expressed much less Notch than those treated with DAPT alone. In the L-OHP group, LRP protein levels were increased significantly, whereas levels were decreased significantly in the DAPT and DAPT + L-OHP groups. DAPT inhibits the proliferation of ovarian cancer stem cells, promotes their apoptosis, weakens their invasive ability, and functions synergistically with L-OHP.