Transglutaminase 2 Induces Intrinsic EGFR-TKI Resistance in NSCLC Harboring EGFR Sensitive Mutations

Abstract

Background: Although non-small cell lung cancer (NSCLC) patients with EGFR sensitizing mutations shows dramatic responsiveness to EGFR-TKI, some of them still showed primary resistance. The loss of PTEN and NF-κB activation have known to contribute to intrinsic EGFR-TKI resistance in EGFR mutant lung cancer. Interestingly, Transglutaminase 2 (TG2) was well known to down-regulate PTEN and IκBα (NF-kB inhibitor) levels in tumor cells. Therefore, we investigated whether TG2 plays a role in the resistance and what kind of mechanisms involves in that resistance. Methods: We have established de novo and ectopic TG2 over-expressing EGFR mutant NSCLC cell lines. Subsequently, we have elaborated the resistance to EGFR-TKI therapy in these TG2-over-expressing cells. We have tried to investigate whether TG2 inhibitor could restore EGFR-TKI sensitivity with EGFR inhibitors in vitro and in vivo. Then, we evaluated TG2 expression in two intrinsic and eight sensitive clinical cases. Findings: The higher TG2 expression and lower PTEN and IκBα expression were evident in the intrinsic EGFR-TKI resistant NSCLC. EGFR-TKI sensitive NSCLC cells, harboring EGFR mutations, that stably expressed TG2 had reduced PTEN and IκBα and exhibited EGFR-TKI resistance. TG2 inhibition alone or co-treatment with TG2 inhibitor and EGFR-TKI in intrinsic EGFR-TKI resistant NSCLC cells harboring EGFR mutations overcame EGFR-TKI resistance via PTEN and IκBα restoration. Interpretation: TG2 elicits intrinsic EGFR-TKI resistance via PTEN loss and activation of the NF-κB pathway in NSCLC harboring EGFR sensitizing mutation. Therefore, TG2 may be a useful predictive marker and also be a target for overcoming the resistance. Funding Statement: This manuscript was supported by a grant from the National R&D Program for Cancer Control, Ministry of Health & Welfare, Republic of Korea (1520220) and the PostGenome Technology Development Program [10067758, Business model development driven by clinico-genomic database for precision immuno-oncology] funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea). Declaration of Interests: D.H.L. declares honoraria from AstraZeneca, Boehringer-Ingelheim, Bristol-Myers Squibb, CJ Healthcare, ChongKunDang, Eli Lilly, Janssen, Merck, MSD, Mundipharma, Novartis, Ono, Pfizer, Roche, Samyang Biopharm and ST Cube. The other authors declare that they have no conflict of interest. Ethics Approval Statement: Animal procedures were approved by the institutional review board of Asan Medical Center