IFN-γ Sensitizes Head And Neck Squamous Cell Carcinoma Cells To Chemotherapy-induced Apoptosis And Necroptosis

Objective:Head and neck squamous cell carcinoma (HNSCC), one of the most common cancer worldwide, remains a challenging clinical problem. Acquired resistance to standard chemotherapy accounts for most of treatment failure. IFN-γ may up-regulate the expression of Major histocompatibility complex class Ⅰ and Ⅱ (MHC-Ⅰ and Ⅱ) molecules and possess anti-tumor potential through immune response. As a potent immunomodifier, IFN-γ also regulates the procession of apoptosis and necroptosis. Early growth response-1(Egr-1) gene is involved in regulating invasive behavior of cancer cells. In the present study, we determined the effect of Egr-1in IFN-γ-induced chemosensitivity in HNSCC. We also described the detailed role of apoptotic and necroptotic mechanisms in cell death process in response to the combination of IFN-γ and cytotoxic drugs.Methods:Specific gene expression at protein and mRNA level was tested by western blot and quantitative real-time reverse transcription-PCR, respectively. Protein secreted in cultured supernatant was measured by ELISA. Plasmid transfection and siRNA transient transfection were performed using the HiPerfect transfection reagent and Lipofectamine2000, respectively. Cell survival was determined by MTT assay.Results:1. Interferon-y (IFN-γ) may up-regulate Egr-1gene expression in HNSCC cell line SCC-25.2. Forced expression of Egr-1sensitizes SCC-25cells to chemotherapy-induced apoptosis and necroptosis, a novel form of receptor-interacting protein kinase (RIPK3)-depended programmed cell death.3. Egr-1up-regulation significantly increases the production of Thrombospondin-1(TSP-1), a matricellular glycoprotein which has been described to induce cell death in HNSCC.4. IFN-y-induced sensitization of cells to chemotherapy-mediated cell death and TSP-1production could be markedly abolished by Egr-1silencing.Conclusions:The present investigation provides the first evidence that IFN-y may sensitize HNSCC cells to chemotherapy-induced apoptosis and necroptosis through up-regulation of Egr-1. These data support the combination use of IFN-y and cytotoxic drugs for HNSCC Therapy.