Abstract 4096: Transglutaminase 2(TG2) induces the intrinsic EGFR-TKI resistance in EGFR-mutant NSCLC

Abstract

Abstract The non-small cell lung cancer (NSCLC) patients with EGFR-sensitive mutations can be therapeutically targeted by EGFR tyrosine kinase inhibitors (EGFR-TKI), such as erlotinib. Unfortunately, even though the intrinsic EGFR-TKI resistant patients harboring the EGFR-sensitizing mutation, a part of those are still resistant to EGFR-TKI. And, it has been reported that both PTEN loss and NF-kB activation contribute to intrinsic EGFR-TKI resistance in EGFR-mutant lung cancer. Transglutaminse 2 (TG2) is post-translational modification enzyme and known to induce degradation of tumor suppressors including PTEN and IκB-α with peptide cross-linking activity. Because TG2 was known as a regulator of PTEN and IκB-α (NF-κB inhibitor) level in cytosol, we have explored if TG2 can be another key regulator to the intrinsic resistance of EGFR-TKI in the intrinsic EGFR-TKI resistant NSCLC cell. In NSCLC with EGFR-sensitive mutations, we first found that higher TG2 expression level and lower PTEN and IκB-α expression levels in the intrinsic EGFR-TKI resistant NSCLC compare with EGFR-TKI sensitive NSCLC. TG2 stably expressing EGFR-TKI sensitive NSCLC cells harboring EGFR mutations showed reduction of both PTEN and IκB-α and exhibited EGFR-TKI resistance. In reverse, TG2 stably downregulated H1650, intrinsic EGFR-TKI resistant NSCLC cell harboring EGFR sensitive mutation, restored EGFR-TKI sensitivity via PTEN and IκB-α restoration by TG2 loss. Xenograft study using TG2 overexpressed and downregulated NSCLC cells also verified our in vitro results. Therefore, we have demonstrated that TG2 elicits the intrinsic EGFR-TKI resistance via PTEN loss and activation of NF-κB pathway. These results suggest that TG2 may be a useful target for overcoming the intrinsic EGFR-TKI resistance of NSCLC harboring EGFR sensitive mutations. Citation Format: Junyoung Choi, Hannah Yang, Sang-We Kim, Kyung Hae Jung, Kang-Seo Park, Dae Ho Lee. Transglutaminase 2(TG2) induces the intrinsic EGFR-TKI resistance in EGFR-mutant NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4096. doi:10.1158/1538-7445.AM2017-4096