title: MIF family members cooperatively inhibit p53 expression and activity.
abstract: The tumor suppressor p53 is induced by genotoxic stress in both normal and transformed cells and serves to transcriptionally coordinate cell cycle checkpoint control and programmed cell death responses. Macrophage migration inhibitory factor (MIF) is an autocrine and paracrine acting cytokine/growth factor that promotes lung adenocarcinoma cell motility, anchorage-independence and neo-angiogenic potential. Several recent studies indicate that the only known homolog of MIF, D-dopachrome tautomerase (D-DT - also referred to as MIF-2), has functionally redundant activities with MIF and cooperatively promotes MIF-dependent pro-tumorigenic phenotypes. We now report that MIF and D-DT synergistically inhibit steady state p53 phosphorylation, stabilization and transcriptional activity in human lung adenocarcinoma cell lines. The combined loss of MIF and D-DT by siRNA leads to dramatically reduced cell cycle progression, anchorage independence, focus formation and increased programmed cell death when compared to individual loss of MIF or D-DT. Importantly, p53 mutant and p53 null lung adenocarcinoma cell lines were only nominally rescued from the cell growth effects of MIF/D-DT combined deficiency suggesting only a minor role for p53 in these transformed cell growth phenotypes. Finally, increased p53 activation was found to be independent of aberrantly activated AMP-activated protein kinase (AMPK) that occurs in response to MIF/D-DT-deficiency but is dependent on reactive oxygen species (ROS) that mediate aberrant AMPK activation in these cells. Combined, these findings suggest that both p53 wildtype and mutant human lung adenocarcinoma tumors rely on MIF family members for maximal cell growth and survival.
authors.affiliation: Molecular Targets Program, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America.
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Brock
authors.affiliation: Molecular Targets Program, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America.
authors.forename: Beatriz E
authors.initials: BE
authors.lastname: Rendon
authors.affiliation: Molecular Targets Program, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America.
authors.forename: Dan
authors.initials: D
authors.lastname: Xin
authors.affiliation: Molecular Targets Program, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America.
authors.forename: Kavitha
authors.initials: K
authors.lastname: Yaddanapudi
authors.affiliation: Molecular Targets Program, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Mitchell
mesh_terms: D055372:AMP-Activated Protein Kinases; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002999:Clone Cells; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000172:deficiency / Q000378:metabolism*; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D008263:Macrophage Migration-Inhibitory Factors / Q000172:deficiency / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010641:Phenotype; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D008263:Macrophage Migration-Inhibitory Factors; D016159:Tumor Suppressor Protein p53; D055372:AMP-Activated Protein Kinases; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase