title: BCL-2 functions as an activator of the AKT signaling pathway in pancreatic cancer.
abstract: BCL-2 is the prototypic anti-apoptotic protein involved in the regulation of apoptosis. Overexpression of BCL-2 is common in pancreatic cancer and confers resistance to the apoptotic effect of chemo- and radiotherapy. Although these cellular effects of BCL-2 are traditionally related to pathways involving the mitochondrial membrane, we sought to investigate whether BCL-2 is involved in other signaling pathways regulating cell survival and focused on AKT. We examined the effect of overexpression of BCL-2 in the MIA-PaCa-2 human pancreatic cancer cell line on the function and subcellular location of AKT. We observed that the stable subclones of MIA-PaCa-2 overexpressing BCL-2 demonstrated increased activity of AKT as well as IKK (a downstream target of AKT), increasing the transcriptional activity of NF-kappaB. Using immunoprecipitation techniques, we observed co-immunoprecipitation of AKT and BCL-2. Immunocytochemistry demonstrated co-localization of BCL-2 and AKT, which was abrogated by treatment with HA14-1, a small molecule inhibitor of BH-3-mediated protein interaction by BCL-2. Furthermore, treatment with HA14-1 decreased phosphorylation of AKT and increased sensitivity to the apoptotic effect of the chemotherapeutic agent, paclitaxel. These results demonstrate an additional mechanism of regulation of cell survival mediated by BCL-2, namely through AKT activation, in the MIA-PaCa-2 pancreatic cancer cell line. Therefore, directed inhibition of BCL-2 may alter diverse pathways controlling cell survival and overcome the apoptotic resistance that is the hallmark of pancreatic cancer.
authors.affiliation: Department of Surgery, University of California Davis School of Medicine, Sacramento, California, USA.
authors.forename: Melinda M
authors.initials: MM
authors.lastname: Mortenson
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Galante
authors.forename: Oren
authors.initials: O
authors.lastname: Gilad
authors.forename: Michael G
authors.initials: MG
authors.lastname: Schlieman
authors.forename: Subbulakshmi
authors.initials: S
authors.lastname: Virudachalam
authors.forename: Hsing-Jien
authors.initials: HJ
authors.lastname: Kung
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bold
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001578:Benzopyrans / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002999:Clone Cells; D018076:DNA, Complementary; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017930:Genes, Reporter; D006801:Humans; D007150:Immunohistochemistry; D049410:Luciferases, Renilla / Q000378:metabolism; D016328:NF-kappa B / Q000502:physiology; D009570:Nitriles / Q000494:pharmacology; D017239:Paclitaxel / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D011233:Precipitin Tests; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D001578:Benzopyrans; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D009570:Nitriles; D019253:Proto-Oncogene Proteins c-bcl-2; C456800:ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate; D049410:Luciferases, Renilla; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D017239:Paclitaxel