CTEN (C-terminal Tensin-like) regulates head and neck cancer invasion and survival

Jason Fleming1,Veronika Jenei1,Karwan Moutasim1,Matthew Ward1,Emma King1,4,Sassan Hafizi2,Dae Kim3,Jeremy Blaydes1,Gareth Thomas1

1University of Southampton, Southampton, UK,2University of Portsmouth, Portsmouth, UK,3St. George’s University Hospitals, London, UK,4Poole Hospital NHS Foundation Trust, Poole, UK

Presenting date: Tuesday 3 November
Presenting time: 16.50-17.05

Background

C-terminal tensin-like (CTEN; TNS4) is a member of the TENSIN gene family that encodes focal adhesion adaptor proteins. CTEN in particular is emerging as a prognostic marker in many cancer types but its mechanism of action and clinical relevance in head and neck cancer (HNSCC) is unknown.

Method

 

We investigated the functional role of CTEN in a panel of head and neck cancer cell lines. Gene knockdown of CTEN was utilised to evaluate function in integrin-dependent assays including transwell invasion assays and physiological 3D organotypic cultures. Clinical correlation was examined through tissue microarray construction and immunohistochemistry analysis of 259 consecutively treated oropharyngeal cancer (OPSCC) patients. Clonogenic assays were performed in a radiosensitive cell line (SCC25) following ionising radiation/cisplatin exposure to identify the effect of CTEN expression on radio/chemosensitivity.

Results

 

CTEN knockdown suppressed invasion of all tested HNSCC cell lines, both in Transwell invasion assays and 3D organotypic cultures (P<0.05). Immunohistochemisty analysis of OPSCC microarray demonstrated that on univariate analysis, high CTEN protein expression predicted shortened disease-free survival (P<0.01). Similarly on multivariate analysis, CTEN independently influenced disease-free survival when adjusted for age, T stage, N stage, and smoking status (P<0.05). Kaplan-Meier survival analysis linked high CTEN expression with significantly reduced overall disease-specific OPSCC survival (P<0.001;log-rank test). This significant correlation was maintained for both HPV-negative (P<0.05) and HPV-positive disease (P<0.01). Interestingly sub-group analysis demonstrated the impact of CTEN expression on survival was most significant in patients treated with chemo-radiation and clonogenic assays suggested a role for CTEN in promoting radioresistence.

Conclusion

Our results suggest that CTEN functions as an oncogene in HNSCC through its promotion of cell invasion. Furthermore, CTEN demonstrates prognostic ability in OPSCC irrelevent of viral status and this may function through a novel role in regulating radiosensitivity. These findings have important implications for head and neck cancer prognosis and targeted treatment of individual patients.