Lactate derived from CAFs mediates H3K18la in stemness gene promoters, which promotes tumor malignant phenotype formation.

Non-small cell lung cancer (NSCLC) is the most common subtype of lung cancer, characterized by high invasiveness, poor prognosis, and limited therapeutic options. Cancer-associated fibroblasts (CAFs), as a core component of the tumor microenvironment (TME), have been shown to promote the malignant progression of NSCLC, but the specific regulatory mechanisms remain incompletely understood. This study aims to investigate the role of CAFs and their metabolic products, particularly lactate, in the progression of NSCLC. CAFs and normal fibroblasts (NFs) were cultured, and the conditioned media (CM) were collected and used to treat NSCLC cells. Cell proliferation was assessed using CCK-8 and EdU assays, while cell migration was evaluated through transwell assays. The expression of E-cadherin and N-cadherin was detected by immunofluorescence (IF). Additionally, lactate levels, gene expression, and lactylation levels were assessed using a lactate detection kit, RT-qPCR, Western blot (WB), and chromatin immunoprecipitation (ChIP). The CM from CAFs enhanced the proliferation, migration, and epithelial-mesenchymal transition (EMT) of NSCLC cells. Our experiments revealed that the metabolites from CAFs, particularly lactate, had a promoting effect on NSCLC. In lactate-treated NSCLC cells, the expression levels of stemness genes were significantly upregulated, accompanied by increased lactylation levels of H3K18. In in vivo experiments, tumors from the lactate treatment group exhibited higher growth rates and increased expression of stemness genes. Furthermore, human NSCLC tumor tissues showed significant upregulation of stemness genes. This study demonstrates that lactate derived from CAFs promotes the expression of stemness genes by mediating H3K18 lactylation in the promoters of these genes in NSCLC cells, thereby accelerating the malignant phenotype formation of NSCLC cells. These findings provide new insights into the role of CAFs in the TME and identify potential therapeutic targets for NSCLC.