Africa leaf (Vernonia amygdalina Delille.) DCM extract synergistically supports growth suppression effect of doxorubicin on MCF7 and MCF7/HER2 with different effects on cell cycle progression and apoptosis evidence

Africa leaf (Vernonia amygdalina Delille) has low cytotoxic activities against several cancer cells. We evaluated its combination treatment with doxorubicin against luminal breast cancer cells against MCF-7 and MCF-7/HER2 cells. The dried leaves were extracted to collect Hexane, Butanol, Dichloromethane (DCM), and ethyl acetate (EA) extracts and were then tested for their cytotoxic activities on MCF7 and MCF7/HER2 cells using MTT assay. The most potential extracts were then examined for cytotoxicity in combination treatment with doxorubicin followed by cell cycle and apoptosis analysis with flow cytometry. All the extracts showed low and no cytotoxic activities against both MCF7 and MCF7/HER2 cells. The DCM extract exhibited a weak cytotoxic activity on both cancer cells with the IC50 values of 220 μg/ml. However, DCM and EA extracts gave synergistic cytotoxic effects with Dox on both cells with strong synergism characteristics. Both extracts induced cell cycle accumulation on the S-phase for DCM and the G1 phase for EA. Both extracts also caused apoptosis with Dox but in different ways in modulating apoptosis. In conclusion, DCM and EA extract of V. amygdalina provide potential synergistic anticancer properties with Dox for luminal breast cancer through cell cycle modulation and apoptosis induction.