Transcription blockage frequently occurs in tumor cells, and aberrant R-loop formation during this process drives genome instability. However, the regulation of R-loop homeostasis and its contribution to tumorigenesis remain to be investigated. Here, we report that the RNA exonuclease REXO4 resolves R-loops by 3'-5' exonucleolytic cleavage of the RNA strand within RNA-DNA hybrids. Accessible RNA ends, generated by endonucleases, are required for this process, and N6-methyladenosine (m6A) modification on RNA moieties promotes REXO4 localization and R-loop removal in human cells. REXO4 ablation-induced DNA damage stimulates an interferon response and tumor immune infiltration, suppressing mouse squamous cell carcinoma (SCC) progression. Importantly, inhibition of REXO4 potentiates the anti-tumor efficacy of PD-1 blockade against SCC by recruiting and activating CD8+ T cells. Thus, our study provides mechanistic insight into how m6A couples with an exonuclease in R-loop clearance and genome maintenance and uncovers a druggable epitranscriptional machinery that constrains the innate immune response and enables SCC immune evasion.
Jieyou Zhang, Kaiwen Bao, Yayan Hou et al.· Molecules and Cells· 0 citations
Inflammatory cancer-associated fibroblasts (iCAFs) are a highly plastic stromal population that critically shapes tumor progression, immunosuppression, and therapeutic response in esophageal squamous-cell carcinoma (ESCC). Epithelial-intrinsic programs are increasingly recognized as key determinants of fibroblast reprogramming within the tumor microenvironment, yet the underlying mechanisms remain incompletely understood. Here, we identified hepatoma-derived growth factor (HDGF) as a pivotal epithelial-intrinsic regulator that drives iCAF formation in ESCC. Mechanistically, nuclear HDGF functioned as a transcriptional activator by directly binding the ENO1 promoter, thereby upregulating the expression of the glycolytic enzyme enolase 1, enhancing aerobic glycolysis, and promoting lactate secretion from tumor cells. Tumor-derived lactate was subsequently taken up by CAFs and induced histone H4 lysine 12 lactylation (H4K12la), which epigenetically activated NF-κB signaling and promoted iCAF formation. Functionally, HDGF-induced iCAFs promoted tumor progression through activation of the IL-6/JAK1/STAT3 axis and established an immunosuppressive microenvironment characterized by increased recruitment of regulatory T cells and reduced infiltration of CD8+ T cells, thereby facilitating immune evasion. Therapeutically, blockade of ENO1 effectively disrupted the glycolysis-lactylation cascade, markedly suppressing tumor growth and iCAF formation in vivo. Moreover, ENO1 inhibition reprogrammed the immunosuppressive tumor microenvironment and significantly enhanced the efficacy of anti-PD-1 therapy. Collectively, our findings reveal an HDGF/ENO1/H4K12la/iCAF axis that links tumor metabolic reprogramming, stromal inflammatory activation, and immunosuppression in ESCC, identifying this axis as a promising therapeutic target for overcoming immunotherapy resistance.
Zhengqing Song, Cainan Li, Pujie Wu et al.· Cancer Letters· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
