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Rescue of K562 cells from MDM2‐modulated p53‐dependent apoptosis by growth factor‐induced differentiation
Author(s) -
Mahdi Tarek,
Alcalay Dominique,
Cognard Christian,
Tanzer Joseph,
Kitzis Alain
Publication year - 1998
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1998.tb01070.x
Subject(s) - k562 cells , biology , transfection , apoptosis , mdm2 , microbiology and biotechnology , cell culture , complementary dna , leukemia , cancer research , immunology , gene , biochemistry , genetics
The wild‐type human MDM2 protooncogene was tested for its ability to modulate apoptotic activity of the de novo expressed p53 tumor suppressor gene in K562 cells. We also studied the role ofsome cytokines in this phenomenon. K562, a human myeloid leukemia cell line, does not express p53 at the mRNA or protein level. In this study, we stably transfected K562 with eukaryotic vectors containing either normal p53 cDNA (pC53‐SN3) or mutated p53 (143 Val→Ala ) cDNA (pC53‐SCX3). Transfectants expressing WT p53 or those expressing mutant p53 are called K562 SN and K562 SM respectively. Many leukemic cell lines undergo apoptosis when de novo WT p53 is expressed alone. In contrast, while the resulting clones (K562 SN and K562 SM) expressed p53, they did not undergo apoptosis. However, when treated with MDM2 mRNA antisense (MDM2 AS) oligodeoxynucleotides (ODNs), K562 SN demonstrated apoptotic features at both molecular and morphological levels. No change was observed when the other clones (K562 and K562 SM) were treated with MDM2 AS. Apoptosis induced in this manner was associated with a relatively small increase in intracellular calcium [Ca 2+ ] i . Cells cultured in medium previously supplemented with recombinant human (rh) interleukin (IL)‐3 and rh‐erythropoietin (Epo) did not undergo apoptosis. Moreover, K562 SN cells were induced to differentiate. This differentiation was evaluated by measuring hemoglobin (Hb) level in cellular extracted proteins and by analyzing erythroid colony number and morphology. High Hb synthesis was obtained when K562 SN cells were cultured with cytokines (IL‐3 + Epo) combined with MDM2 AS. Our results are consistent with the hypothesis that the function of the proto‐oncogene MDM2 is to provide a ‘feedback’ mechanism for the p53‐dependent pathway of apoptosis that could be shunted toward differentiation.