Decitabine and Vorinostat Cooperate To Sensitize Colon Carcinoma Cells to Fas Ligand-Induced Apoptosis In Vitro and Tumor Suppression In Vivo

Abstract

The death receptor Fas and its physiological legend, FasL, regulate apoptosis of cancerous cells, thereby functioning as a critical component of the host cancer immunosurveillance system. To evade Fas-mediated apoptosis, cancer cells often down-regulate Fas to acquire an apoptosis-resistant phenotype, which is a hallmark of metastatic human colorectal cancer. Therefore, targeting Fas resistance is of critical importance in Fas-based cancer therapy and immunotherapy. Here we demonstrated that epigenetic inhibitors, Decitabine and Vorinostat, cooperate to up-regulate Fas expression in the metastatic human colon carcinoma cells. Decitabine also up-regulates BNIP3 and Bik expression, whereas Vorinostat decreased Bcl-xL expression. Altered expression of Fas, BNIP3, Bik and Bcl-xL resulted in effective sensitization of the metastatic human colon carcinoma cells to FasL-induced apoptosis. Using an experimental metastasis mouse model, we further demonstrated that Decitabine and Vorinostat cooperate to suppress colon carcinoma metastasis. Analysis of tumor-bearing lung tissues revealed that a large portion of tumor-infiltrating CD8+ T cells are FasL+, and Decitabine and Vorinostat-mediated tumor suppression efficacy was significantly decreased in Fasgld mice as compared to wt mice, suggesting a critical role of FasL in Decitabine and Vorinostat-mediated tumor suppression in vivo. Consistent with their function in apoptosis sensitization, Decitabine and Vorinostat significantly increased the efficacy of CTL adoptive transfer immunotherapy in an experimental metastasis mouse model. Our data thus suggest that combined modalities of chemotherapy to sensitize the tumor cell to Fas-mediated apoptosis and CTL immunotherapy is an effective approach for the suppression of colon cancer metastasis.

Deregulation of Apoptotic Factors Bcl-xL and Bax Confers Apoptotic Resistance to Myeloid-derived Suppressor Cells and Contributes to Their Persistence in Cancer

“…Apoptosis Assays-For in vitro apoptosis assay, cells were treated with ABT-737 and FasL for ϳ16 -24 h and then stained with FITC-CD11b mAb, PE-Gr1 mAbs, Alex Fluor 647-annexin V (all from Biolegend, San Diego, CA), and 4Ј,6-diamidino-2-phenylindole (DAPI), and analyzed by flow cytometry as previously described (40,42). For spontaneous MDSC apoptosis assay, a single-cell suspension was prepared from spleens in cold PBS.…”

“…Cell Surface Marker Analysis-Cells were stained with fluorescence-conjugated antibody as previously described (42). Fluorescent dye-conjugated anti-CD4, CD8, CD11b, Gr1, Fas, and FasL mAbs were obtained from Biolegend.…”

Inhibitors of Enzymes Catalyzing Modifications to Histone Lysine Residues: Structure, Function and Activity

“…HDAC inhibitors currently used for cancer treatment include vorinostat 12, romidepsin 13, belinostat 14 and panobinostat 15 ( Figure 6). DNA methylation is guided by histone acetylation and combinations of HDAC and DNA methyltransferase inhibitors are synergistic in sensitizing colon carcinoma cells to Fas ligand-induced apoptosis in vitro and tumor suppression in vivo [115]. Combinations of vorinostat and the DNA methyltransferase inhibitor decitabine have recently finished Phase I and Phase II clinical trials for treatment of some types of leukemia [116,117].…”

Selective inhibition of esophageal cancer cells by combination of HDAC inhibitors and Azacytidine

“…32,33 Importantly, synergistic effects of HDACi and the DNMT inhibitor DAC were reported for growth inhibition, DNA damage, and apoptosis induction in different tumor entities. [34][35][36] Again, the underlying mechanism of action is not validated yet, but HDACi appear to decelerate removal of incorporated DAC from DNA, thereby enhancing the harmful action of DAC. 37 In the setting of the 2 major types of esophageal cancer, this study addressed the basic molecular effects (e.g.…”