Abstract 2968: TWIST1-induced suppression of oncogene-induced senescence in non-small cell lung cancer requires the transactivation domain of TWIST1

Abstract Non-small cell lung carcinoma (NSCLC) is a major cause of cancer mortality. High expression of the epithelial-to-mesenchymal transition transcription factor TWIST1 is strongly associated with metastatic cancers and treatment resistance. Additionally, TWIST1 can upregulate O-GlcNAcylation which (1) is required to suppress fail-safe programs such as oncogene (KRasG12D)-induced senescence (OIS) to accelerate tumorigenesis in primary NSCLC tumors, and (2) is a potential modulator of DNA repair/radiation response. To decipher the domains and transcriptional targets required for tumorigenicity and radioresistance, we created a novel genetically engineered mouse model (GEMM) allowing tetracycline-inducible expression in the lung epithelium (via lung specific CCSP-reverse tetracycline transactivator (C)) of KRasG12D (R) with Twist1wt (T) or with Twist1F191G transactivation-null mutant (F). CRT mice had shorter tumor-free survival and more aggressive tumors compared to CR/CRF mice indicating that the Twist1 transactivation domain is required for Twist1-dependent tumorigenesis acceleration. Also, Twist1wt expression promoted radioresistance in cell lines and GEMMs. Contrary to CRT, CRF showed a progressive loss of Twist1F191G expression over time suggesting no functionality/no selective advantage. CRT lung tumors had higher proliferation (Ki67) and lower cell-cycle arrest (p16) compared to CR/CRF suggesting that the transactivation domain of Twist1 is important for the suppression of OIS. Supporting these data, we observed in non-cancer Human Bronchial Epithelial Cell (HBEC) that the co-expression of human TWIST1wt (HBEC-TWIST1wt) could suppress HRasG12V-induced senescence while the transactivation-null TWIST1F187G mutant (HBEC-TWIST1F187G) could not. Additionally, HBEC expressing HRasG12V-TWIST1wt had enhanced tumorigenic/invasive programs. Interestingly, we observed that the inhibition of O-GlcNAcylation rescued OIS in HBEC-HRasG12V-TWIST1wt while the stimulation of O-GlcNAcylation in HBEC-HRasG12V-TWIST1F187G suppressed OIS. Furthermore, TWIST1wt expression with HRasG12V modulated MYC downstream targets and the inhibition of MYC activity using the novel MYC inhibitor MYCi975 in HBEC-HRasG12V-TWIST1wt also rescued OIS induction. Altogether, these results suggest that TWIST1 may suppress OIS via MYC signaling and nominate MYCi975 as a means to activate latent OIS programs. In this context, MYC inhibiting strategies could serve as a therapeutic sensitizer for TWIST1-positive NSCLC. This work and our future studies on TWIST1 toward the control of OIS, O-GlcNAcylation and of mechanisms of radioresistance may help to identify new potential NSCLC therapeutic strategies. Citation Format: Audrey M. Lafargue, Hailun Wang, Sivarajan T. Chettiar, Rajendra P. Gajula, Amol C. Shetty, Yang Song, Brian W. Simons, Triet Nguyen, Christine Lam, Francesca A. Carrieri, Caleb Smack, Nick Connis, Dipanwita Dutta Chowdhury, Jinhee Chang, Danielle Council, Katriana Nugent, Ismaeel Siddiqui, Kekoa Taparra, Mohammad Rezaee, Natasha Zachara, Zachary S. Morris, Christopher McFarland, Sarki Abba Abdulkadir, Christine L. Hann, Phuoc T. Tran. TWIST1-induced suppression of oncogene-induced senescence in non-small cell lung cancer requires the transactivation domain of TWIST1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2968.