title: Activation of FOXO3a is sufficient to reverse mitogen-activated protein/extracellular signal-regulated kinase kinase inhibitor chemoresistance in human cancer.
abstract: Drug resistance is a central challenge of cancer therapy that ultimately leads to treatment failure. In this study, we characterized a mechanism of drug resistance that arises to AZD6244, an established mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) 1/2 inhibitor currently being evaluated in cancer clinical trials. AZD6244 enhanced the expression of transcription factor FOXO3a, which suppressed cancer cell proliferation. In AZD6244-resistant cancer cells, we observed the impaired nuclear localization of FOXO3a, reduced FOXO3a-mediated transcriptional activity, and decreased the expression of FOXO3a target gene Bim after cell treatment with AZD6244. Resistant cells could be sensitized by phosphoinositide 3-kinase (PI3K)/AKT inhibitors, which are known to enhance FOXO3a nuclear translocation. Our findings define FOXO3a as candidate marker to predict the clinical efficacy of AZD6244. Furthermore, they suggest a mechanism of resistance to MEK inhibitors that may arise in the clinic yet can be overcome by cotreatment with PI3K/AKT inhibitors.
authors.affiliation: Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Jer-Yen
authors.initials: JY
authors.lastname: Yang
authors.forename: Chun-Ju
authors.initials: CJ
authors.lastname: Chang
authors.forename: Weiya
authors.initials: W
authors.lastname: Xia
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Kwok-Kin
authors.initials: KK
authors.lastname: Wong
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Engelman
authors.forename: Yi
authors.initials: Y
authors.lastname: Du
authors.forename: Michael
authors.initials: M
authors.lastname: Andreeff
authors.forename: Gabriel N
authors.initials: GN
authors.lastname: Hortobagyi
authors.forename: Mien-Chie
authors.initials: MC
authors.lastname: Hung
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001562:Benzimidazoles / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002747:Chlorpropamide / Q000031:analogs & derivatives / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D009369:Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D000096926:Benzenesulfonamides
chemical_list: D001562:Benzimidazoles; D002747:Chlorpropamide; D002867:Chromones; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; C111224:API 2; D000096926:Benzenesulfonamides; C517975:AZD 6244; C499517:FOXO3 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C482128:MAP2K2 protein, human; C482125:MAP2K1 protein, human