Department of Cancer Biology; Department of Biochemistry and Molecular Pharmacology; Department of Surgery; Department of Medicine, Division of Hematology/Oncology
Medical Subject Headings
Alcohol Oxidoreductases; Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Chromatin Immunoprecipitation; Colonic Neoplasms; DNA-Binding Proteins; HCT116 Cells; Humans; Membrane Proteins; Methionine; Mice; Mice, Nude; Repressor Proteins; Transplantation, Heterologous; Tumor Suppressor Protein p53
The CtBP transcriptional corepressors promote cancer cell survival and migration/invasion. CtBP senses cellular metabolism via a regulatory dehydrogenase domain, and is antagonized by p14/p19(ARF) tumor suppressors. The CtBP dehydrogenase substrate 4-methylthio-2-oxobutyric acid (MTOB) can act as a CtBP inhibitor at high concentrations, and is cytotoxic to cancer cells. MTOB induced apoptosis was p53-independent, correlated with the derepression of the proapoptotic CtBP repression target Bik, and was rescued by CtBP overexpression or Bik silencing. MTOB did not induce apoptosis in mouse embryonic fibroblasts (MEFs), but was increasingly cytotoxic to immortalized and transformed MEFs, suggesting that CtBP inhibition may provide a suitable therapeutic index for cancer therapy. In human colon cancer cell peritoneal xenografts, MTOB treatment decreased tumor burden and induced tumor cell apoptosis. To verify the potential utility of CtBP as a therapeutic target in human cancer, the expression of CtBP and its negative regulator ARF was studied in a series of resected human colon adenocarcinomas. CtBP and ARF levels were inversely-correlated, with elevated CtBP levels (compared with adjacent normal tissue) observed in greater than 60% of specimens, with ARF absent in nearly all specimens exhibiting elevated CtBP levels. Targeting CtBP may represent a useful therapeutic strategy in human malignancies.
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Citation: Cell Cycle. 2010 Sep 15;9(18):3740-50. Epub 2010 Sep 8. Link to article on publisher's site