title: Complementation by wild-type p53 of interleukin-6 effects on M1 cells: induction of cell cycle exit and cooperativity with c-myc suppression.
abstract: Stable transfection of M1 myeloid leukemia cells with a temperature-sensitive mutant of p53 results in two phenomena that are manifested exclusively at the permissive temperature. On one hand, activation of wild-type p53 by the temperature shift induced an apoptotic type of cell death which could be inhibited by interleukin-6 (IL-6) (E. Yonish-Rouach, D. Resnitzky, J. Lotem, L. Sachs, A. Kimchi, and M. Oren, Nature 352:345-347, 1991). On the other hand, as reported in this work, activated p53 complemented the antiproliferative effects of IL-6 in M1 cells. A shift to the permissive temperature concomitant with or early after IL-6 treatment imposed a novel pattern of cell cycle arrest in which about 95% of the cells were retained within a G0-like quiescent state. This phase was characterized by 2N DNA content and low RNA and protein content. On the molecular level, activation of wild-type p53 transrepressed the c-myc gene but not the cyclin A, D1, or D2 gene, which are all independently suppressed by IL-6 in M1 cells. To further analyze whether c-myc inhibition mediates or complements p53 effects, the p53-transfected M1 cells were infected with a retroviral vector expressing deregulated c-myc, refractory to p53 or IL-6 action. It was found that the process of cell death was not interrupted at all in these M1 c-myc-p53 double transfectants, suggesting that the transrepression of c-myc is not a major obligatory event mediating p53-induced cell death. In addition, some of the antiproliferative effects of activated p53, manifested in the presence of IL-6, could still be transmitted in the background of constitutive c-myc. Yet the context of deregulated c-myc interfered with the final accumulation of cells within a G0-like phase, suggesting complementary interactions between the outcome of p53 activation and of c-myc suppression in the control of cell cycle arrest.
authors.affiliation: Department of Molecular Genetics and Virology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: N
authors.initials: N
authors.lastname: Levy
authors.forename: E
authors.initials: E
authors.lastname: Yonish-Rouach
authors.forename: M
authors.initials: M
authors.lastname: Oren
authors.forename: A
authors.initials: A
authors.lastname: Kimchi
mesh_terms: D002453:Cell Cycle / Q000187:drug effects* / Q000235:genetics; D005809:Genes, Regulator / Q000187:drug effects; D016259:Genes, myc; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology*; D013489:Suppression, Genetic; D013696:Temperature; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000494:pharmacology*
chemical_list: D015850:Interleukin-6; D016159:Tumor Suppressor Protein p53