Search for the genes regulated by Histone deaetylase inhibitor and the Rb gene

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HDAC inhibitors, such as FK228 and trichostatin A(TSA), induce growth arrest and apoptosis in a variety of human cancer cells. We evaluated cytotoxicity by MTS assay and FACS analysis after 72 h of exposure to FK228 or TSA in 20 human lung cancer cell lines including 15 non-small cell lung cancer(NSCLC) and 5 small cell lung cancr(SCLC) cell lines. We found both FK228 and TSA steeply inhibited cell growth and induced apoptosis in 20 cell lines with nanomolar concentrations.To investigate genes to sensitivity of lung cancers cells to FK228, TSA and 9 chemotherapeutic agents including CDDP, CBDCA, VP-16, SN-38 Paclitaxel, Docetaxel, Vinorelbine, Gemcitabine, SM5887, we performed cDNA microarray analysis of 20 lung cancer cells. A clustering algorithm applied to the expression data showed distinguished subgroups between HDAC inhibitors and 9 chemotherapeutic agents. In addition, we compared the expression data with IC50 data of cell lines. We found significant associations between sensiti … More vity to HDAC inhibitors and expression levels of several genes including CST3, but failed to confirm their significant association by real-time PCR method.The retinoblastoma tumor suppressor protein(RB) is targeted for inactivation in the majority of human tumors, including NSCLC and SCLC. RB inhibits proliferation by repressing the transcription of genes that are essential for cell cycle progression and restoration of the Rb gene to SCLC cells has been shown to suppress the tumorigenecity in vitro. To repress transcription, RB functionally antagonize E2F acitivity through binding E2Fs directly and assembling multiprotein complexes containing chromatin-modifying enzymes, including histone deacetylases(HDACs). However, the extent to which HDACs participate in transcriptional repression and are required for RB-mediated repression is unclear. Since the HDAC inhibitors induced apoptosis in NSCLC and SCLC cells. We examined whether reconstitution of the Rb gene to lung cancer cells blocks the HDAC-induced apoptotic pathway. Combined treatment of HDAC inhibitors with Adenovirus-Rb or Adenovirus-LacZ as a control similarly showed additive to mild synergistic effects by combination index method, indicating reconstitution of Rb did not block the HDAC inhibitor-induced apoptosis. Less