Identification of potential target genes of cardiac glycosides from Vernonia amygdalina Delile in HER2+ breast cancer cells

Abstract

Vernonia amygdalina Delile or bitter leaf, a traditional medicinal plant endemic to Africa, has shown anticancer properties by inhibiting the downstream signaling of human epidermal growth factor receptor 2 (HER2) in several cancer cells through the PI3K/AKT/mTOR pathways. This study explored the potential target of Vemonia cardiac glycosides for the treatment of HER2+ breast cancer (CTG) using bioinformatics and in vitro experiments. The similarity ensemble technique Swiss TargetPrediction was used to predict protein targets of cardiac glycosides. DisGeNET and UALCAN were used to collect the regulatory genes of HER2+ breast cancer cells. We obtained 75 CTG sequences from the predicted target and regulatory genes of HER2+ breast cancer. Subsequent analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment revealed that CTG was enriched for multiple pathways, such as PI3K-Akt signaling, breast cancer, EGFR tyrosine kinase inhibitor resistance, and ErbB signaling pathways. Further bioinformatic analysis identified five CTG: ERBB2, ESR1, EGFR, PIK3CA, and PTPN11. The ethanolic extract and its ethyl acetate fraction of V. amigdalina were referred to as REF and EA, respectively. Cytotoxicity tests showed that EA exerted strong cytotoxicity on MCF-7/HER2 cells by inducing S-phase cell cycle arrest and apoptosis, modulating the mRNA expression of CTG: ERBB2, ESR1, and proliferation and apoptosis markers, PCNA, CCND1, BAX, BCL2, and CASP7. Future studies should develop EA and cardiac glycosides as anticancer agents against HER2+breast cancer cells.