Ceramide Signaling in the Regulation of Head & Neck Cancer Cell Death and Therapy

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SUMMARY Human papilloma virus (HPV) plays major roles in head and neck squamous cell carcinoma (HNSCC) pathogenesis. Paradoxically, HPV(+) HNSCC patients respond better to chemotherapy, such as cisplatin (CDDP), compared to HPV(-) HNSCC patients. However, molecular mechanisms and signaling pathways involved in HPV-mediated chemosensitivity are largely unknown. Thus, the overall goal of this application is to define the mechanisms involved in chemosensitivity of HNSCC cells in response to HPV infection with regard to ceramide metabolism and signaling. Our therapeutic goal is to utilize this mechanistic information for the development of novel strategies to enhance chemotherapy-induced HNSCC cell death and tumor suppression without HPV infection. Based on our novel and unpublished preliminary data, we propose a novel hypothesis that HPV16-E7 enhances CerS1/C18-ceramide-dependent lethal mitophagy in response to chemotherapy- induced cellular stress signaling, leading to enhanced HNSCC cell death and tumor suppression. This hypothesis will be tested in three Specific Aims: 1) Determine the roles of HPV16-E6 versus HPV16-E7 in the regulation of ceramide-mediated lethal mitophagy; 2) Determine the mechanisms by which HPV16-E7 signaling enhances ceramide-dependent lethal mitophagy; and 3) Define the therapeutic roles and mechanisms of HPV16-E7 signaling in the regulation of ceramide-dependent lethal mitophagy and HNSCC tumor suppression. Overall, these studies will help develop mechanism-based therapeutic strategies to induce HPV16-E7/C18-ceramide-mediated lethal mitophagy signaling for improving tumor suppression by chemotherapy in HNSCC patients.