title: Deoxycholic acid and selenium metabolite methylselenol exert common and distinct effects on cell cycle, apoptosis, and MAP kinase pathway in HCT116 human colon cancer cells.
abstract: The cell growth inhibition induced by bile acid deoxycholic acid (DCA) may cause compensatory hyperproliferation of colonic epithelial cells and consequently increase colon cancer risk. On the other hand, there is increasing evidence for the efficacy of certain forms of selenium (Se) as anticancer nutrients. Methylselenol has been hypothesized to be a critical Se metabolite for anticancer activity in vivo. In this study, we demonstrated that both DCA (75-300 micromol/l) and submicromolar methylselenol inhibited colon cancer cell proliferation by up to 64% and 63%, respectively. In addition, DCA and methylselenol each increased colon cancer cell apoptosis rate by up to twofold. Cell cycle analyses revealed that DCA induced an increase in only the G1 fraction with a concomitant drop in G2 and S-phase; in contrast, methylselenol led to an increase in the G1 and G2 fractions with a concomitant drop only in the S-phase. Although both DCA and methylselenol significantly promoted apoptosis and inhibited cell growth, examination of mitogen-activated protein kinase (MAPK) pathway activation showed that DCA, but not methylselenol, induced SAPK/JNK1/2, p38 MAPK, ERK1/2 activation. Thus, our data provide, for the first time, the molecular basis for opposite effects of methylselenol and DCA on colon tumorigenesis.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota, USA. huawei.zeng@ars.usda.gov
authors.forename: Huawei
authors.initials: H
authors.lastname: Zeng
authors.forename: James H
authors.initials: JH
authors.lastname: Botnen
authors.forename: Mary
authors.initials: M
authors.lastname: Briske-Anderson
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000201:enzymology / Q000473:pathology*; D003840:Deoxycholic Acid / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D016193:G1 Phase / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects; D045325:HCT116 Cells; D006801:Humans; D000432:Methanol / Q000031:analogs & derivatives* / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016566:Organoselenium Compounds / Q000494:pharmacology*; D016196:S Phase / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D016566:Organoselenium Compounds; D003840:Deoxycholic Acid; C019003:methaneselenol; D020928:Mitogen-Activated Protein Kinases; D000432:Methanol