Cytotoxic effect of Ziziphus Spina-Christi extract alone and in combination with doxorubicin on breast cancer cells

Ziziphus Spina-Christi (L.) (ZSC) is a traditional Arabian medicinal plant used to treat inflammatory symptoms, swellings and pain since long. Triple negative breast cancer (TNBC) is a form of cancer with a poor prognosis owing to the paucity of therapy alternatives. Two of the most critical pathways of TNBC development are Wnt/β-catenin signaling and autophagy. In the present study, we intended to identify the possible mechanisms of the cytotoxic effects mediated by ZSC extract on MDA-MB-231 breast cancer cells and to improve the efficacy of DOX in combination with ZSC. The MTT test was used to estimate cell viability and IC50 values. Apoptosis was detected using AnnexinV-FITC detection kit. ELISA was used to measure caspase-3 levels. Cell cycle and the level of autophagosome marker LC3-II were analysed using flow cytometry. Acidic vesicular organelle (AVOs) formation was observed by fluorescence microscopy. Real-time PCR was used to monitor changes in gene expression of β-catenin and autophagic adapter NBR1. It was shown that ZSC treatment dose-dependently inhibited MDA-MB-231 cell viability and induced apoptosis with accompanying elevation of caspase-3 level. Besides ZSC caused a significant elevation in LC3II level and downregulation of NBR1 gene expression with subsequent downregulation of β-catenin gene expression, indicating the inhibition of the oncogenic Wnt pathway. ZSC and DOX combination had synergistic cytotoxic effect by more effective suppression of Wnt pathway and induction of apoptosis and autosis. Keywords: apoptosis, autophagic adapter NBR1, autophagosome marker LC3-II, breast cancer cells, DOX, Wnt/β-catenin signaling, Ziziphus Spina-Christi