Abstract 2682: STK11-loss-dependent YAP1-mediated transcriptional activation promotes immune evasion in KRAS-driven lung adenocarcinoma

Abstract

Abstract Why Serine Threonine Kinase 11 (STK11) loss of function (LoF) correlates with anti-PD1 therapy resistance in the context of KRAS-driven lung adenocarcinomas remains unclear and represents a critical outstanding question in the field. To address this, we knocked out STK11 in KRAS-driven human lung adenocarcinoma cell lines and performed RNAseq to identify STK11-loss-dependent differentially expressed genes. Subsequent pathway enrichment analyses implied activation of the HIPPO/YAP1 signaling network occurs in the absence of STK11. Based on work linking YAP1 with transcriptional regulation of cytokine-mediated inflammation and immune-evasion in colorectal cancer and gastric cancer, we wondered whether YAP1 activation might impact anti-PD1 therapy response in KRAS-driven lung cancers lacking STK11. To evaluate this possibility, we applied a YAP1 transcriptional signature to the differentially expressed genes and performed gene set enrichment analysis (GSEA) revealing a strong positive correlation between STK11 LoF and upregulation of YAP1 target genes, most notably induction of IL-6, IL-8 and IL-32. To validate YAP1-mediated transcriptional activation is downstream of STK11 loss, we reasoned we could rescue STK11-loss-dependent YAP1-mediated cytokine induction by genetic disruption of YAP1, or pharmacologic inhibition of YAP1 with verteporfin. STK11/YAP1 double knock-out cell lines express significantly less IL-6, IL-8 and IL-32 compared with STK11 KO lines. Further, inhibition of YAP1 with verteporfin phenocopied YAP1 genetic disruption in these cell lines, changes mirrored at the level of secreted protein. Finally, we demonstrate YAP1 chromatin occupancy is STK11-dependent. Together these data link STK11 LoF with YAP1-mediated transcriptional activation, specifically the upregulation of immune-evasion promoting cytokines including IL-6, IL-8 and IL-32. We posit these STK11-loss-dependent YAP1-mediated tumor-intrinsic changes could result in anti-PD1 therapy resistance and immune-evasion by promoting recruitment of myeloid-derived suppressor cells, neutrophils and T-regulatory cells to the tumor microenvironment. Further, our results indicate that YAP1 antagonism may represent a valid therapeutic approach to circumvent STK11-loss-dependent transcriptional changes and potentially restore sensitivity to anti-PD1 therapy. Elucidating the mechanism(s) linking STK11 with YAP1 transcriptional activation and evaluating the potential for beneficial therapeutic intervention remains the focus of our continuing work. Citation Format: David Joseph Seward. STK11-loss-dependent YAP1-mediated transcriptional activation promotes immune evasion in KRAS-driven lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2682.