Cytotoxic effect of DEBIO 1143 on Triple Negative Mouse Breast Cancer Cell Lines by Non-Apoptosis Death Mechanisms

Abstract

Background Triple negative breast cancer (TNBC) is a lethal cancer lacking therapeutic targets. In this project, we aimed to investigate the cytotoxic effect of DEBIO 1143, a SMAC mimetic, on 4T1 and 4T1-HER2 mouse TNBC cell lines and the cell death pathway through which this effect is mediated. Methods and results MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test was used to determine cell viability, flow cytometry analysis was performed to determine apoptosis, and MDC (monodansylcadaverine) was used to determine autophagic vesicles. In addition, LC3II, Beclin 1, RIP3 and cIAP1 proteins were analyzed by western blot. In both cell lines, it was determined that DEBIO 1143 IC50 doses caused predominantly non-apoptotic cell death in the 48-h drug-treated group. In western blot analysis, LC3II level was significantly increased in 4T1-HER2 cells treated with DEBIO 1143 for 24 and 48 hours compared to control. Beclin 1 expression was significantly elevated in the drug treatment groups of both cell lines. The expression level of RIP3 in 4T1 cells was relatively increased after 24 and 48 h treatment of DEBIO 1143 compared to control. cIAP1 protein bands were detected in both control and 24- h treatment groups of both cell lines, but not in 48- h treatment groups. Conclusions Our findings revealed that DEBIO 1143 showed a time-dependent cytotoxic effect in mouse TNBC cell lines. This effect may be predominantly mediated through non-apoptosis cell death mechanisms such as autophagy and necrosis. Further research is recommended to clarify the issue fully.