Abstract 3320: Identification of potential molecular targets related to radioresistance in human oral cancers
Authors: Teni Tanuja R. , Yasser Mohd , Pawar Sagar 
Published: August 2015

In India, oral cancer is the most common cancer in males and ranks third among females, attributed predominantly to the use of smokeless tobacco. Radiotherapy is an integral part of oral cancer treatment either alone or in combination with surgery and chemotherapy. However the development of radioresistance creates a hurdle in the efficacy of radiotherapy. Therefore, exploring the differential molecular profile of established radioresistant versus parental oral cancer cells may help in predicting the clinical effectiveness of radiotherapy.

The present study aims to profile the radioresistant cell lines established by low dose radiation from their parental oral cancer cell lines, to identify the molecules and the possible mechanisms associated with radioresistance in oral cancer.

We have established three radioresistant oral cancer cell lines i.e. 70Gy-AW13516, 70Gy-AW8507 and 70Gy-SCC029B derived from their parental AW13516, AW8507 and SCC029B cell lines respectively using in-vitro fractionated ionizing radiation (FIR). A clinically admissible 2Gy radiation dose was given using a 60Co-γ linear accelerator (Bhabhatron-2, ACTREC) upto 70Gy totally for each of the cell lines. The radioresistant character was determined by clonogenic cell survival assay and proteomic profiling of parental versus radioresistant cells was done by two-dimensional gel electrophoresis. Gels were analysed by PD-Quest software (Bio-Rad) and differential spot identities were revealed by MALDI-TOF/TOF (Bruker Ultra flex-II). To explore changes at transcript level; cDNA microarray was performed by Affymetirx Gene Chip array and analysed by Gene Spring GX-12.5 software.

Mass spectrometry (MS) identified a total of 106 differentially expressed proteins among the three replicate sets of each parental and radioresistant 2-D gels with significant MS/MS score. Some of the differentially expressed proteins like Prohibitin, Moesin, PCNA, Keratin-8, Vimentin, HSP-70 and 14-3-3 sigma were validated by western blotting. We further, transiently knocked down Moesin expression by siRNA strategies and demonstrated a significant decrease in the radioresistant character of 70Gy-AW13516 cells as compared to control siRNA treated cells, indicating a role for Moesin in acquired radioresistance of oral cancer cells. Also differentially expressed genes (&gt;3 fold) of radioresistant cells, were mapped by David (NIH) & Panther (USC) functional tools. The pathway analysis revealed genes related to cell survival (PI3K, P38), Wnt and Apoptosis signalling.

The proteomic and transcriptomic profiling of radioresistant oral cancer cell lines have revealed several radioresistance associated molecules that may be utilised in predicting cellular response to radiotherapy and the pathways identified may provide new insights in understanding the mechanism underlying clinical radioresistance in oral cancers.

Citation Format: Tanuja R. Teni, Mohd Yasser, Sagar Pawar. Identification of potential molecular targets related to radioresistance in human oral cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3320. doi:10.1158/1538-7445.AM2015-3320