The combination of Elephantopus scaber and Phaleria macrocarpa leaves extract promotes anticancer activity via downregulation of ER-α, Nrf2 and PI3K/AKT/mTOR pathway

Background: Elephantopus scaber and Phaleria macrocarpa have recently been interested as novel anticancer agents. However, there was no scientific evaluation of the anticancer effect of both plant combinations.

Objective: This study investigated the potential anticancer effects of combined E. scaber and P. macrocarpa leaves extract on human breast cancer cells lines.

Materials and methods: T47D cells were treated with the combination of E. scaber and each part of P. macrocarpa (leaves/EL, mesocarp/EM, seed/ES and pericarp/EP). T47D cells were then exposed to three ratios (1:1, 2:1, and 1:2) of the best combination for 24, 48, and 72 h. The cell viability of T47D and TIG-1 cells was assessed using WST-1 assay. The apoptotic hallmarks were determined using FITC Annexin V-PI staining and DNA fragmentation assay. The cell proliferation and cell cycle profiles were analyzed using CFSE (carboxyfluorescein succinimidyl ester) and Propidium iodide-flowcytometry assays. The relative number of p-ERα, p-Nrf2, p-PI3K, p-AKT, and p-mTOR were assessed using flow cytometry. The molecular docking analysis was also performed to confirm the mechanism of the extract in silico.

Results: The combination of E. scaber and P. macrocarpa leaves (EL) possessed strong cytotoxic activity (p < 0.05) than other combination groups and cisplatin. EL showed selective killing only to T47D cells. EL at a ratio of 2:1 potentially suppressed the cell viability and cell division, induced apoptosis, and arrested the cell cycle of T47D cells by triple inhibiting the p-Nrf2, p-ERα, and p-PI3K/AKT/mTOR signaling pathway. Molecular docking analysis confirmed that the possible mechanism of EL to reduce T47D cell growth was by inhibiting ERα and Nrf2-complex, resulting in the reduction in the crosstalk effect of Nrf2, ERα and PI3K/AKT/mTOR pathways.

Conclusion: The combination of leaf extracts from E. scaber and P. macrocarpa caused cell death in breast cancer cells T47D and not in normal cells TIG-1; hence has the potential to show anticancer efficacy in preclinical and clinical trials.