Methanolic Leaves Extract of Ziziphus spina-christi Inhibits Cell Proliferation and Migration of HER2-Positive Breast Cancer via p38 MAPK Signaling Pathway.

Human epidermal growth factor receptor 2 (HER2) is a subtype of breast cancer that is associated with poor prognosis and low survival rates. The discovery of novel anti-cancer agents to manage this subtype of cancer is still needed. Ziziphus spina-christi (ZSC) is a plant species that is native to Qatar. It exerts various biological activities, including cytotoxicity as it contains different essential bioactive constituents, mainly rutin and quercetin. To examine the outcome of ZSC on HER2-positive breast cancer, we standardized the ZSC methanolic leaves extracted by Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) analysis using the flavonoids rutin and quercetin as marker compounds. Here we used two HER2-positive breast cancer cell lines, ZR-75-1 and SK-BR-3, and the chorioallantoic membrane as an angiogenesis model. We found that ZSC extract significantly reduces viability, alters the normal morphological phenotype of HER2-positive breast cancer cells, and inhibits cell migration as well as colony formation; this is accompanied by deregulating different apoptotic markers such as Bax/Bcl-2 and NF-κB in both cell lines. Additionally, ZSC methanolic extract significantly represses the angiogenesis of the chorioallantoic membrane model. Moreover, the molecular pathway investigations pointed out that ZSC extract represses the activity of HER2 and p38 MAPK which could be the main pathways behind the effect of ZSC in HER2-positive cells. Collectively, our results support the potential role of ZSC in the management of HER2-positive breast cancer and form the basis for future investigations.