Developing a Single-Chain Variable Fragment Antibody against Nicotinic Acetylcholine Receptor 5 and Estimating Its Therapeutic Effectiveness on Enhancing the Radiosensitivity in Oral Cancer

Oral cancer is a type of head and neck cancer and may originate in any of the tissues from mouth. Radiotherapy is the major strategy to treat oral cancer in current clinics; however, a subpopulation of oral cancer patients who are insensitive to irradiation treatment have a poorer prognosis. Therefore, identifying biomarkers for predicting radiosensitivity or developing new therapeutic strategies to enhance therapeutic response against irradiation is urgently needed in oral cancer patients. Previous studies have demonstrated the role for nicotinic acetylcholine receptors in tumorigenesis or cancer progression (e.g. metastasis or drug resistance). Moreover, our preliminary data demonstrated that CHRNA5, a gene encoding nicotinic acetylcholine receptor 5, is highly expressed in primary tumors compared to normal adjacent tissues derived from oral cancer patients deposited in The Cancer Genome Atlas (TCGA) database. Moreover, the high-level of CHRNA5 transcript was shown to correlate with the poor survival rates in oral cancer patients. Particularly in oral cancer patients who were recorded to receive radiation therapy, CHRNA5 upregulation significantly predicted a poor recurrence-free survival probability. On the other hand, cell-based assay revealed that the endogenous mRNA levels of CHRNA5 positively correlates with the radiosensitivy of the tested oral cancer cell lines. However, further studies are still needed to explore the molecular mechanism in which CHRNA5 upregulation drives radioresistance and the practical application of targeting CHRNA5 or its related signaling axis in oral cancer. To achieve this goal, in this proposed 3-year study, we will investigate the following Specific Aims: (1) To evaluate the functional consequence of CHRNA5 knockdown or overexpression in the radiosensitivity of oral cancer cells in vitro; (2) To estimate the radiosensitivity of oral cancer cells after CHRNA5 knockdown or overexpression in vivo; (3) To generate a chicken-derived single chain variable fragment antibody against CHRNA5 ectodomain; (4) To determine the therapeutic effectiveness of CHRNA5 neutralization by the generated single chain variable fragment antibody on enhancing radiosensitivity in oral cancer cells in vitro and in vivoThe data obtained from this proposed study will highlight a prognostic significance of CHRNA5 in oral cancer patients who are deciding to receive irradiation treatment. Moreover, the therapeutic effectiveness of the generated single chain variable fragment antibody against CHRNA5 on enhancing radiosensitivity will offer a new strategy to combat radioresistant oral cancer clinically.