Nuclear expression of WRAP53β is associated with a positive response to radiotherapy and improved overall survival in patients with head and neck squamous cell carcinoma.

Today there are no reliable predictive markers for radiotherapy response in head and neck squamous cell carcinoma (HNSCC), leading to both under- and over-treatment of patients, personal suffering, and negative socioeconomic effects. Inherited mutation in WRAP53β (WD40 encoding RNA Antisense to p53), a protein involved in intracellular trafficking, dramatically increases the risk of developing HNSCC. The purpose of this study was to investigate whether WRAP53β can predict response to radiotherapy in patients with HNSCC. Tumor biopsies from patients with HNSCC classified as responders or non-responders to radiotherapy were examined for the expression of the WRAP53β protein and single nucleotide polymorphisms in the corresponding gene employing immunohistochemistry and allelic discrimination, respectively. In addition, the effect of RNAi-mediated downregulation of WRAP53β on the intrinsic radiosensitivity of two HNSCC cell lines was assed using crystal violet and clonogenic assays. Nuclear expression of WRAP53β was significantly associated with better response to radiotherapy and improved patient survival. Downregulation of WRAP53β with siRNA in vitro enhanced cellular resistance to radiation. Our findings suggest that nuclear expression of WRAP53β promotes tumor cell death in response to radiotherapy and is a promising predictor of radiotherapy response in patients with HNSCC.