Tumor Necrosis Factor a-Dependent Lung Inflammation Promotes the Progression of Lung Adenocarcinoma Originating From Alveolar Type II Cells MIF-CD74

Lung adenocarcinoma is the most common type of lung cancer. We recently reported that inflammation-driven lung adenocarcinoma (IDLA) originates from alveolar type (AT)-II cells, which depend on major histocompatibility complex (MHC) class II to promote the expansion of regula-tory T cells. The MHC class II-associated invariant chain (CD74) binds to the macrophage migration inhibitory factor (MIF), which is associated with promoting tumor growth and invasion. However, the role of MIF-CD74 in the progression of lung adenocarcinoma and the underlying mechanisms remain unclear. We aimed to explore the role of MIF-CD74 in the progression of lung adenocar-cinoma and elucidate the mechanisms by which tumor necrosis (TNF)-a-mediated inflammation regulates CD74 and MIF expression in IDLA. In human lung adenocarcinoma, CD74 was upregu-lated on the surface of tumor cells originating from AT-II cells, which correlated positively with lymph node metastasis, tumor origin/nodal involvement/metastasis stage, and TNF-a expression. MIF interaction with CD74 promoted the proliferation and migration of A549 and H1299 cells in vitro. Using a urethane-induced IDLA mouse model, we observed that CD74 was upregulated in tumor cells and macrophages. MIF expression was upregulated in macrophages in IDLA. Blocking TNF-a-dependent inflammation downregulated CD74 expression in tumor cells and CD74 and MIF expression in macrophages in IDLA. Conditioned medium from A549 cells or activated mouse AT-II cells upregulated MIF in macrophages by secreting TNF-a. TNF-a-dependent lung inflammation contributes to the progression of lung adenocarcinoma by upregulating CD74 and MIF expression, and AT-II cells upregulate MIF expression in macrophages by secreting TNF-a. This study provides novel insights into the function of CD74 in the progression of IDLA. (c) 2022 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.