Effect of tetrandrine combined with arsenic trioxide on stem cells of triple negative breast cancer

Abstract

Background Although the triple negative breast cancer is sensitive to chemotherapy, breast cancer stem cells (BCSCs) is the origin of tumor chemotherapy resistance, tumor recurrence and tumor invasion and metastasis. This study aims to examine the effect of tetrandrine combine with arsenic trioxide on BCSCs and potential mechanism of anti- triple negative breast cancer metastasis. Methods We cultured the triple negative breast cancer cell MDA-MB-231 and induced BCSCs sphere formation by serum-free medium for 5 days. In the MDA-MB-231 cell and MDA-MB-231 stem cell, we compared the ratio of CD44+/CD24- and sorted stem cells by flow cytometry, the expression of Oct4 and Sox2mRNA were by rt-PCR, invasion ability were by Transwell assay. We subsequently measured the effect of tetrandrine combine with arsenic trioxide on BCSCs proliferation by CCK8 method. The stem cell morphology observation was by trypan blue staining. Stem cell cycle and apoptosis were evaluated by flow cytometry. Western Blot was used to measure the protein levels of Hedgehog, Notch1 and PTEN signaling of BCSCs. Results The ratio of CD44+/CD24- in MDA-MB-231 stem cells was 95.0%, while MDA-MB-231 cell was 89.3%. The invasion number of MDA-MB-231 stem cell was significantly higher than that of MDA-MB-231 cells (p<0.01). Furthermore, we demonstrated that tetrandrine and arsenic trioxide could inhibit the BCSCs proliferation. Tetrandrine combine with arsenic trioxide could significantly promote the apoptosis (p<0.01) and increase the percentage of G0/G1 phase and decrease the G2/M phase (p<0.01) of BCSCs. Compared with the control group, arsenic trioxide, tetrandrine and the combined group could significantly reduce the expression of GLI1 and SMO and increase the expression of PTEN protein (P<0.05). Conclusions These findings revealed that tetrandrine combined with arsenic trioxide could suppress the proliferation and induce apoptosis of BCSCs by decreased Gli and SMO expression and increased PTEN expression. Targeting BCSCs treatment, this study provides potential therapeutic drugs against triple negative breast cancer metastasis.