Tumor-specific induction of apoptosis by a p53-reactivating compound.
The tumor suppressor function of p53 is disabled in the majority of tumors, either by a point mutation of the p53 gene, or via MDM2-dependent proteasomal degradation. We have screened a chemical library using a cell-based assay and identified a low molecular weight compound named MITA which induced wild-type p53-dependent cell death in a variety of different types of human tumor cells, such as lung, colon and breast carcinoma cells, as well as in osteosarcoma and fibrosarcoma-derived cells. MITA inhibited p53-MDM2 interaction in vitro and in cells, which in turn prevented MDM2-mediated ubiquitination of p53 and resulted in a prolonged half-life and accumulation of p53 in tumor cells. Notably, p53 induction by MITA resulted in upregulated expression of p53 target genes MDM2, Bax, Gadd45 and PUMA, on protein and mRNA level. Importantly, neither p53 nor these target genes were induced in normal human fibroblasts (HDFs), which correlated with the absence of growth suppression in fibroblasts after treatment with MITA. However, upon activation of oncogenes in fibroblasts an induction and activation of p53 was observed, suggesting that activation of p53 by MITA occurs predominantly in tumor cells.
Hedström
Elisabeth
E
The Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Box 280, SE-171 77, Stockholm, Sweden.
Issaeva
Natalia
N
Enge
Martin
M
Selivanova
Galina
G
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D006801:Humans; D011485:Protein Binding; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D054852:Small Molecule Libraries; D015533:Transcriptional Activation / Q000187:drug effects; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D015854:Up-Regulation
D000970:Antineoplastic Agents; D054852:Small Molecule Libraries; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2