Lung squamous cell carcinomas (LSCC) pathogenesis remains incompletely understood and biomarkers predicting treatment response remain lacking. Here we describe novel murine LSCC models driven by loss of Trp53 and Keap1, both of which are frequently mutated in human LSCCs. Homozygous inactivation of Keap1 or Trp53 promoted airway basal stem cell (ABSC) self-renewal, suggesting that mutations in these genes lead to expansion of mutant stem cell clones. Deletion of Trp53 and Keap1 in ABSCs, but not more differentiated tracheal cells, produced tumors recapitulating histological and molecular features of human LSCCs, indicating that they represent the likely cell of origin in this model. Deletion of Keap1 promoted tumor aggressiveness, metastasis, and resistance to oxidative stress and radiotherapy (RT). KEAP1/NRF2 mutation status predicted risk of local recurrence after RT in non-small lung cancer (NSCLC) patients and could be non-invasively identified in circulating tumor DNA. Thus, KEAP1/NRF2 mutations could serve as predictive biomarkers for personalization of therapeutic strategies for NSCLCs.

During development, the formation of a mature, well-functioning heart requires transformation of the ventricular wall from a loose trabecular network into a dense compact myocardium at mid-gestation. Failure to compact is associated in humans with congenital diseases such as left ventricular non-compaction (LVNC). The mechanisms regulating myocardial compaction are however still poorly understood. Here, we show that deletion of the Ino80 chromatin remodeler in vascular endothelial cells prevents ventricular compaction in the developing mouse heart. This correlates with defective coronary vascularization, and specific deletion of Ino80 in the two major coronary progenitor tissues-sinus venosus and endocardium-causes intermediate phenotypes. In vitro, endothelial cells promote myocardial expansion independently of blood flow in an Ino80-dependent manner. Ino80 deletion increases the expression of E2F-activated genes and endothelial cell S-phase occupancy. Thus, Ino80 is essential for coronary angiogenesis and allows coronary vessels to support proper compaction of the heart wall.

The MAPK pathway mediates TLR signaling during innate immune responses. We discovered previously that MKP-1 is acetylated, enhancing its interaction with its MAPK substrates and deactivating TLR signaling. As HDACs modulate inflammation by deacetylating histone and nonhistone proteins, we hypothesized that HDACs may regulate LPS-induced inflammation by deacetylating MKP-1. We found that mouse macrophages expressed a subset of HDAC isoforms (HDAC1, HDAC2, and HDAC3), which all interacted with MKP-1. Genetic silencing or pharmacologic inhibition of HDAC1, -2, and -3 increased MKP-1 acetylation in cells. Furthermore, knockdown or pharmacologic inhibition of HDAC1, -2, and -3 decreased LPS-induced phosphorylation of the MAPK member p38. Also, pharmacologic inhibition of HDAC did not decrease MAPK signaling in MKP-1 null cells. Finally, inhibition of HDAC1, -2, and -3 decreased LPS-induced expression of TNF-α, IL-1β, iNOS (NOS2), and nitrite synthesis. Taken together, our results show that HDAC1, -2, and -3 deacetylate MKP-1 and that this post-translational modification increases MAPK signaling and innate immune signaling. Thus, HDAC1, -2, and -3 isoforms are potential therapeutic targets in inflammatory diseases.

Purpose: Activation of NFE2L2 has been linked to chemoresistance in cell line models. Recently, somatic mutations that activate NFE2L2, including mutations in NFE2L2, KEAP1, or CUL3, have been found to be associated with poor outcomes in patients with non-small cell lung cancer (NSCLC). However, the impact of these mutations on chemoresistance remains incompletely explored.Experimental Design: We investigated the effect of Keap1 deletion on chemoresistance in cell lines from Trp53-based mouse models of lung squamous cell carcinoma (LSCC) and lung adenocarcinoma (LUAD). Separately, we identified 51 patients with stage IV NSCLC with KEAP1, NFE2L2, or CUL3 mutations and a matched cohort of 52 wild-type patients. Time to treatment failure after first-line platinum doublet chemotherapy and overall survival was compared between the two groups.Results: Deletion of Keap1 in Trp53-null murine LUAD and LSCC resulted in increased clonogenic survival upon treatment with diverse cytotoxic chemotherapies. In patients with NSCLC, median time to treatment failure (TTF) after first-line chemotherapy for the KEAP1/NFE2L2/CUL3-mutant cohort was 2.8 months compared with 8.3 months in the control group (P < 0.0001). Median overall survival (OS) was 11.2 months in the KEAP1/NFE2L2/CUL3mutant group and 36.8 months in the control group (P ¼ 0.006).Conclusions: Keap1 deletion confers chemoresistance in murine lung cancer cells. Patients with metastatic NSCLC with mutations in KEAP1, NFE2L2, or CUL3 have shorter TTF and OS after first-line platinum doublet chemotherapy compared with matched controls. Novel approaches for improving outcomes in this subset of patients with NSCLC are therefore needed.