AMPK‑activated protein kinase activation by Impatiens balsamina L. is related to apoptosis in HSC‑2 human oral cancer cells

Objective: In the present study, we investigated the efficacy of a methanol extract from Impatiens balsamina L. (MEIB) against HSC‑2 human oral cancer cells. Materials and Methods: The anti‑cancer efficacies of MEIB were performed by methanethiosulfonate assay, phospho‑kinase array, Western blot, 4’‑6‑diamidino‑2‑phenylindole staining, trypan blue exclusion assay and 5,5’,6,6’‑tetrachloro‑1,1’,3,3’‑tetraethylbenzimidazolylcarbocyanine iodide assay. Results: MEIB decreased the cell viability of HSC‑2 cells. According to phospho‑kinase arrays, MEIB markedly activated AMP‑activated protein kinase (AMPK) signaling, but inactivated mammalian target of rapamycin signaling. MEIB induced apoptosis as evidenced by activation of caspase‑3, poly (ADP‑ribose) polymerase cleavage and nuclear condensation. In addition, AMPK activation by two known activators (5‑aminoimidazole‑4‑carboxamide‑1‑β‑ribofuranoside and metformin) decreased cell viability and induced apoptosis. Moreover, MEIB increased the expression levels of mitochondria‑related proteins (t‑Bid, Bak and Bad), which contributed to the disruption of mitochondrial membrane potential, cytochrome C release and activation of caspase‑9. Metformin also increased t‑Bid expression and the subsequent release of cytochrome C into the cytosol. Conclusion: These results suggest that MEIB may be of therapeutic value for treating oral cancer and that its mechanism of action occurs through AMPK and t‑Bid.