LAUSR

KRAS and LKB1 are frequently co-mutated in lung adenocarcinoma and characterize a particularly aggressive, metastatic, and treatment-resistant subtype of this disease. We recently published that the outputs of biological rhythm pathways downstream of the AMPK kinase are altered in KRAS/LKB1-mutant tumors. In a live-cell phenotyping screen we used RNAseq to identify the circadian clock genes PER1 and PER2 as uniquely upregulated in partially transformed and invasive KRAS/LKB1-mutant human bronchial epithelial cells. We have analyzed expression of individual circadian clock genes in KRAS-mutant and KRAS/LKB1-mutant patient tumors and found that expression of the PER genes, particularly PER1, is increased in the KRAS/LKB1 subtype of lung adenocarcinoma. At the protein level, PER1 expression is increased in KRAS/LKB1-mutant HBECs as compared to KRAS-mutant cells. Addback of wild-type LKB1 in A549 cells, which are KRAS/LKB1-mutant, results in a decrease in PER1 protein levels, confirming that LKB1 has a role in controlling PER1 levels. Multiple phosphorylation events lead to PER1 nuclear translocation to control its role as a transcriptional repressor in the core clock. In circadian-synced HBECs, PER1 enters the nucleus in KRAS-mutant cells, but remains cytosolic in KRAS/LKB1-mutant cells. In circadian-synced A549 cells, we also observed a lack of nuclear PER1 localization. Addback of wild-type LKB1 restored nuclear localization of PER1, as did expression of kinase-dead LKB1, suggesting that LKB1’s regulation of PER1 localization is kinase-independent. Our current and future experiments aim to determine how clock-controlled gene expression may be altered in KRAS/LKB1-mutant cells, what the functional impact of altered PER1 expression and localization is on growth of KRAS/LKB1-mutant tumors, and whether pharmacological manipulation of LKB1-related signaling pathways can restore nuclear localization of PER1. Citation Format: Rebecca E. Parker, Junghui Koo, Bhakti Dwivedi, Adam I. Marcus, Melissa Gilbert-Ross. Defining the role of PER1 and circadian rhythm dysregulation in KRAS/LKB1-mutant lung adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference: Targeting RAS; 2023 Mar 5-8; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Res 2023;21(5_Suppl):Abstract nr A027.