title: AMPK-activated protein kinase activation by Impatiens balsamina L. is related to apoptosis in HSC-2 human oral cancer cells.
abstract: 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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Oral Pathology, School of Dentistry, Institute of Oral Bioscience, Chonbuk National University, Jeonju, 561-756, Republic of Korea.
authors.forename: Ji-Ae
authors.initials: JA
authors.lastname: Shin
authors.affiliation: Department of Food Science and Nutrition, College of Health Welfare and Education, Gwangju University, Gwangju, Republic of Korea.
authors.forename: Ki Han
authors.initials: KH
authors.lastname: Kwon
authors.affiliation: Department of Oral Pathology, School of Dentistry, Institute of Oral Bioscience, Chonbuk National University, Jeonju, 561-756, Republic of Korea.
authors.forename: Sung-Dae
authors.initials: SD
authors.lastname: Cho
keywords: AMP-activated protein kinase; Impatiens balsamina L; apoptosis; oral cancer; t-Bid