Abstract 2818: Investigating TNIK as a radiosensitizing target in lung squamous cell carcinoma
Authors: Nguyen Triet M. , Lafargue Audrey M. , Carrieri Francesca A. , Connis Nick , Chang Jinhee , Jagtap Shreya , Torres-Ayuso Pedro , Brognard John , Hann Christine L. , Tran Phuoc T. 
Published: April 2023

Abstract
In this study, we investigated the potential of TNIK inhibition as a radiosensitizing strategy in lung squamous cell carcinoma (LSCC). LSCC is a type of lung malignancy that accounts for about 30% of all lung cancer cases. As there are no known actionable oncogenic drivers in LSCC, there is currently no FDA-approved targeted therapy for LSCC patients. Most still receive chemotherapy and radiotherapy for locally advanced disease. As such, there is a critical need for the identification of therapeutic targets in LSCC. The protein kinase TNIK represents a potential target for therapeutic intervention. A positive regulator of the Wnt signaling pathway, TNIK is implicated in promoting tumorigenesis and treatment resistance in different cancers. Importantly, TNIK copy number amplification is a signature genomic alteration in LSCC as it is observed in about 50% of LSCC patients. Recently, it was shown that disrupting TNIK activity with NCB-0846, a small-molecule inhibitor of TNIK, inhibited the proliferation of TNIKhigh LSCC tumors. To extend this finding, we investigated whether TNIK inhibition can sensitize LSCC tumors to chemo- and radiotherapy. By employing NCB-0846 and a panel of LSCC cell lines with low and high TNIK expression, we conducted short-term and long-term cell viability experiments to evaluate the synergy between TNIK inhibition and chemo- and radiotherapy. The combination of NCB-0846 with conventional chemotherapeutic agents was antagonistic. Interestingly, we observed that treating LSCC cells with NCB-0846 prior to ionizing radiation (IR) enhanced the tumor-killing effects of IR in a TNIK-specific fashion. The radiosensitizing effect was only observed in TNIKhigh but not in TNIKlow cell lines. Further mechanistic studies suggested that TNIK inhibition may radiosensitize LSCC tumors by impairing the endogenous DNA damage repair process and G2/M cell cycle arrest in response to IR. Consequently, tumor cells incurred elevated DNA damage from IR and underwent more catastrophic cell division events. To test whether TNIK inhibition radiosensitizes in vivo, we subcutaneously implanted in immunocompromised NSG mice LK2 (TNIKhigh) and KNS62 (TNIKlow) human LSCC cells. The mice were treated with (1) vehicle control, (2) NCB-0846 only, (3) IR only, or (4) IR following pre-treatment with NCB-0846. We observed that pretreatment with NCB-0846 significantly potentiated the efficacy of IR in eradicating TNIKhigh LK2 tumors but not TNIKlow KNS62 tumors. Overall, these results indicate that TNIK inhibition may be a viable strategy to enhance the efficacy of radiotherapy in LSCC tumors with high TNIK expression.
Citation Format: Triet M. Nguyen, Audrey M. Lafargue, Francesca A. Carrieri, Nick Connis, Jinhee Chang, Shreya Jagtap, Pedro Torres-Ayuso, John Brognard, Christine L. Hann, Phuoc T. Tran. Investigating TNIK as a radiosensitizing target in lung squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2818.