The study aims to elucidate the pharmacological mechanism of Rauvolfia tetraphylla against breast cancer through a comprehensive, multi-faceted approach. This includes molecular docking, molecular dynamics, and experimental validation. Initial screening via ADME analysis and network pharmacology identified key compounds and potential targets. Protein-protein interaction (PPI) network analysis pinpointed Yes-associated protein-1 (YAP) as a crucial target. Molecular docking revealed that three compounds-ajmaline, reserpine, and serpentine-exhibited strong binding affinities with YAP, with scores of -6.5 to -6.7 kcal/mol. Molecular dynamics simulations were conducted to assess the stability of these interactions further. Experimental validation showed R. tetraphylla inhibited breast cancer cell proliferation, with an IC50 of 348.69 μg/mL, while demonstrating cytoprotective effects on Vero cells (IC50: 1056.23 μg/mL). Migration assays indicated an 88.5% reduction in cell migration, and increased ROS levels signaled elevated stress in cancer cells. Apoptosis was confirmed by AO/EtBr staining. In vivo validation in a DMBA-induced mouse model confirmed significant tumor growth inhibition, supported by changes in YAP expression and histopathological analysis. These findings highlight R. tetraphylla as a promising therapeutic candidate against breast cancer, offering insights into its mechanisms and potential for future drug development and clinical applications.
We investigated the role of protein arginine methylation (PAM) in estrogen receptor (ER)-positive breast cancer cells through pharmacological intervention. Tamoxifen (TAM) or adenosine dialdehyde (ADOX), independently, triggered cell cycle arrest and down-regulated PAM, as reduced protein arginine methyltransferase1 (PRMT1) mRNA and asymmetric dimethylarginine (ADMA) levels. Synergistic effect of these compounds elicited potent anti-cancer effect. However, reduction in ADMA was not proportionate with the compound-induced down-regulation of PRMT1 mRNA. We hypothesized that the disproportionate effect is due to the influence of the compounds on other methyltransferases, which catalyze the arginine dimethylation reaction and the diversity in the degree of drug-protein interaction among these methyltransferases. In silico analyses revealed that independently, ADOX or TAM, binds with phosphatidylethanolamine-methyltransferase (PEMT) or betaine homocysteine-methyl transferase (BHMT); and that the binding affinity of ADOX with PEMT or BHMT is prominent than TAM. These observations suggest that in breast cancer, synergistic effect of ADOX + TAM elicits impressive protective function by regulating PAM; and plausibly, restoration of normal enzyme activities of methyltransferases catalyzing arginine dimethylation could have clinical benefits.