Abstract LB187: Investigating the roles of ROR1/2 in non-small cell lung carcinoma NSCLC and potential therapeutic applications
Authors: Pan Wen-An , Guo Xin , Galang Christina , Ko Mira , Kucharski Jeff , Miller Nicole , Moskowitz Haim , Watkins Jeff , Lannutti Brian , Jessen Katti , Liu Hao 
Published: April 2024

Abstract
Lung cancer is the leading cause of cancer mortality worldwide, representing an unmet medical need. Receptor tyrosine kinase-like orphan receptors (RORs) are oncofetal antigens that act as receptors/co-receptors of WNT5A and other related noncanonical WNT proteins, in transducing β-catenin independent WNT signaling. Dysregulated ROR/WNT have been linked to cancer progression and therapy resistance. Recently, ROR receptors have drawn increasing attention as anti-cancer targets of antibody-drug conjugates (ADCs) due to their selective expression on the tumor cell surface. The ROR family contains ROR1 and ROR2, which share 58% sequence homology. However, their functional interactions between ROR/WNT5A and whether RORs have distinct or redundant roles in tumor phenotypes remain unclear. In this study, we sought to address these biological questions in NSCLC, and investigate the potential application of anti-ROR therapies. To this end, we used CRISPR/Cas9 to generate clones of ROR1 or ROR2 single knockouts (KOs) in the NSCLC LCLC-103H cell line and implemented an array of assays to characterize the effect of single ROR KOs. ROR KOs were confirmed by both western blot and flow cytometry. We found reduced ROR2 mean fluorescence intensity (MFI) on ROR1 KOs and increased ROR1 MFI on ROR2 KOs in flow cytometrical analysis. Phenotypically, ROR1 KOs did not affect tumor doubling time, but ROR2 KOs promoted cell proliferation in 2D cultures. Unlike 2D cultures, tumor 3D spheroid proliferation was significantly inhibited in both ROR1 and ROR2 KOs, implying that each ROR is indispensable in maintaining tumor growth featured by cell-cell/extracellular matrix interactions. Mechanistically, ROR1 KOs tended to decrease ROR2 and WNT5A/B protein expression, while ROR2 KOs caused compensatory upregulation of ROR1 and WNT5A/B. Both ROR1 and ROR2 KOs decreased SNAIL expression, which is a key driver of epithelial-to-mesenchymal plasticity (EMP). Furthermore, alterations in ROR1/2 signaling pathways were observed. We have identified pathways downstream of ROR1/2 including WNT, EMP, and survival, which may shed light on the biological roles of RORs in cancer and potential therapeutic intervention. Finally, the therapeutic application of ROR1/2 was evaluated by monomethyl auristatin F (MMAF) containing anti-ROR ADCs. ROR1 KOs demonstrated the on-target cytotoxicity of anti-ROR1 ADC, while ROR2 KOs showed increased sensitivity to anti-ROR1 ADC due to the increased ROR1 expression in ROR2 KOs. In vivo analysis is currently underway. Collectively, our results demonstrate that RORs have both distinct and compensatory functions in regulating tumor proliferation. We believe a greater understanding in ROR1/2 biology may lead to better targeted therapeutic applications.
Citation Format: Wen-An Pan, Xin Guo, Christina Galang, Mira Ko, Jeff Kucharski, Nicole Miller, Haim Moskowitz, Jeff Watkins, Brian Lannutti, Katti Jessen, Hao Liu. Investigating the roles of ROR1/2 in non-small cell lung carcinoma NSCLC and potential therapeutic applications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB187.