Abstract 5829: Elucidating the significance of amphiregulin and its implications for EGFR inhibition strategies in LKB1-mutant NSCLC
Authors: Solone Xzaviar Kaymar , Zhou Xin , Yu Mu , Li Jennifer W. , Rimay Finn , Kaye Frederic , Wu Lizi 
Published: March 2024

Abstract
LKB1-mutant non-small cell lung cancer (NSCLC) is aggressive and treatment-refractory, underscoring the need for new therapeutic strategies. Our comparative study involving mouse lung tumors driven by oncogenic KrasG12D and LKB1 loss as well as tumors driven solely by KrasG12D, revealed that LKB1 loss upregulated amphiregulin (Areg), a pro-growth EGFR ligand. Therefore, this study investigates how the inactivation of LKB1 enhances AREG expression, the significance of elevated AREG in sustaining lung cancer growth, and the responses of AREG-high lung cancer to EGFR inhibitors. We first evaluated the potential clinical significance of AREG using The Cancer Genome Atlas (TCGA) lung adenocarcinoma dataset and the Cancer Cell Line Encyclopedia (CCLE) database. We observed that LKB1-null tumors with high AREG levels were associated with shorter patient survival and exhibited transcriptional signatures similar to EGFR-mutant tumors. High AREG expression also correlated positively in NSCLC cell lines with LKB1 mutations and Western blot analysis confirmed that elevated AREG levels in lung cancer cells were associated with constitutive EGFR signaling. We next explored the impact of LKB1 loss on AREG expression in lung cancer. Our prior RNA-seq and ChIP-seq investigations demonstrated CRTC2 and CREB enrichment on the AREG promoter in LKB1-null lung cancer cells. Upon LKB1 reintroduction, the enrichment diminished, indicating that CRTC-CREB transcriptionally induces AREG in LKB1-null lung cancer. To corroborate, reintroducing LKB1 or expressing a dominant-negative construct (dnCRTC), disrupting CREB/CRTC interaction, decreased AREG levels, as confirmed by RT-qPCR in LKB1-null lung cancer cells. This supports that AREG is a direct target of CRTC-CREB activation induced by LKB1 loss. To assess the impact of elevated AREG in LKB1-mutant lung cancer growth, we used RNA interference and antibodies to inhibit AREG. Both interventions decreased cell growth and colony formation, underscoring AREG is critical for LKB1-mutant lung cancer growth. Moreover, we investigated the potential correlation between AREG and the response to the EGFR tyrosine-kinase inhibitor Erlotinib in NSCLC cell lines, utilizing AREG expression data from CCLE and Erlotinib response data from the Genomics of Drug Sensitivity in Cancer (CDSC) databases. Stratifying NSCLC cell lines into sensitive, intermediate, and resistant categories revealed a potential positive association between AREG expression and Erlotinib sensitivity. Notably, LKB1-null lung cell lines with high AREG expression demonstrated heightened sensitivity compared to those with low AREG expression. Our study revealed that LKB1 loss increases AREG, triggering aberrant EGFR signaling critical for lung cancer growth, and AREG expression might impact the Erlotinib response in LKB1-inactive cells.
Citation Format: Xzaviar Kaymar Solone, Xin Zhou, Mu Yu, Jennifer W. Li, Finn Rimay, Frederic Kaye, Lizi Wu. Elucidating the significance of amphiregulin and its implications for EGFR inhibition strategies in LKB1-mutant NSCLC [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 5829.