Abstract 5476: CIP2A can be a therapeutic target of rapamycin in radioresistant head and neck cancer with P53 mutation

The presence of p53 mutation was associated with poor survival in various tumors. The involvement of p53 in apoptosis and cell-cycle control makes it a plausible biomarker of prognosis . Classifying TP53 mutations in HNSCC described disruptive TP53 mutation in either the L2 or L3 loop of the DNA binding domain, resulting in polarity change within the protein, or stop cordon. Disruptive TP53 mutation in HNSCC tumors predicts for locoregional recurrence, due to increased radioresistance via the inhibition of senescence. Senescence induction contributes to cancer therapy responses and is crucial for p53-mediated tumor suppression. However, whether p53 inactivation actively suppresses senescence induction has been unclear. Here, we found that overexpression CIP2A (cancerous inhibitor of protein phosphatase 2A) positively correlated with presence of p53 mutation in head and neck cancer and mediates radioresistance through suppression of radiation induced senescence. And we demonstrated that rapamycin could induce senescence via CIP2A downregulation and increase radiosensitivity in p53 disruptive mutation cell line. This is the first investigation to analyze the role of CI2A in resistance to the radiotherapy of head and neck cancer. As a consequence, a greater understanding of radioresistance mechanisms through our results in head and neck cancer with p53 mutation will enable the rational design of combination regimens and sequential treatment algorithms to improve clinical outcomes and points to the usefulness of CIP2A as a biomarker to predict clinical response to rapamycin in head and neck cancer. Citation Format: Song Hee Kim, Won hyeok Lee, Myung Jin Lee, Hyo Won Chang, Ji Won Kim, Mi Ra Kim, Jung Je Park, Myung Woul Han, Sang Yoon Kim. CIP2A can be a therapeutic target of rapamycin in radioresistant head and neck cancer with P53 mutation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5476. doi:10.1158/1538-7445.AM2017-5476