Identification Of Genes Involved In Chemoradiation Response Of Head And Neck Cancer By Functional Genetic Screens

Introduction: Patients with advanced head and neck squamous cell carcinoma (HNSCC) are treated with cisplatin-containing chemoradiation protocols, but tumor responses can be short-lasting. For these patients surgery combined with postoperative radiotherapy is preferred over chemoradiation. Currently, there are no strong predictors of chemoradiation response that would allow to personalize treatment. We performed a functional genetic siRNA screen to identify genes that can be used to predict upfront which tumors are likely to respond to chemoradiation. Methods: A large panel of HNSCC cell lines was characterized for cisplatin sensitivity. A suitable HNSCC cell line was selected and forward transfected with a genome-wide library of short interfering RNAs (siRNAs), followed by cisplatin (IC20 and IC80) or mock treatment. Genes influencing cellular response to cisplatin were identified by comparing cell viability between the different conditions. The screen was carried out in duplicate and data were analyzed by Z-score calculation using two independent statistical methods. Results: Scrambled siRNAs and siRNAs targeting genes known to influence cell viability or cisplatin sensitivity were included as controls and gave the expected results: less than 10% toxicity and >80% knock-down. Hit lists obtained with both methods of data analysis revealed 86 siRNAs that appeared to influence cisplatin response significantly. Some of these 86 siRNAs target genes that are known to cause sensitivity to cisplatin, thereby confirming the reliability of the approach. We also obtained a list of 80 genes that influenced basic cell viability of HNSCC cells independent of cisplatin. Conclusion: By specifically knocking down all human genes in HNSCC cells, we obtained an unbiased list of at least 86 candidate genes that seem to influence the cellular response to cisplatin. Refined statistical analysis combined with bioinformatics, the exclusion of off-target effects, as well as confirmation of the hits in multiple cell lines is needed to validate these results. Validated hits will be evaluated as predictive markers in clinical samples. This research was supported by the Center for Translational Molecular Medicine (AIRFORCE project). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1750. doi:10.1158/1538-7445.AM2011-1750