ARNTL deregulation promotes ovarian cancer progression and metastasis by activating cancer-associated fibroblasts

Circadian disruption fuels tumor growth, but the role of the core clock gene aryl hydrocarbon receptor nuclear translocator-like (ARNTL) in ovarian cancer is still unclear. We investigated how ARNTL affects ovarian cancer cell proliferation, invasion, and migration, and revealed how it shapes these behaviors by acting on the fibroblast-rich tumor microenvironment. We engineered SKOV3 cells to either overexpress or silence ARNTL and then measured how fast they migrated, invaded, and proliferated. RNA sequencing (RNA-seq) and pathway analyses were performed, while Microenvironment Cell Populations-counter (MCP-counter) scored fibroblast abundance. In vivo, ovarian cancer cells were subcutaneously inoculated into immunodeficient mice to monitor tumor growth kinetics and quantify proliferative capacity at the organismal level. Single-cell RNA-seq of the tumors and in vitro co-cultures with cancer-associated fibroblasts (CAFs) uncovered how ARNTL re-programs the fibroblast-rich microenvironment to suppress cancer progression. Here, we found that ARNTL, a circadian core gene, is downregulated in ovarian cancer, and its abundance is negatively correlated with tumor proliferation, invasion, and metastasis. In vitro and in vivo models demonstrated that restoring ARNTL not only inhibits cancer cell proliferation and metastasis, but also reshapes the tumor microenvironment by reducing CAFs recruitment and activation. Mechanistically, ARNTL knockdown promotes PI3K-Akt/TGF-β signaling in ovarian cancer cells and induces CAF activation. Activated CAFs exhibit increased secretion of Stromal Cell-Derived Factor-1 (SDF-1) and Platelet-Derived Growth Factor (PDGF), which reciprocally enhance ovarian cancer cell proliferation and metastatic capacity. Our study indicates that ARNTL functions as a potent tumor suppressor by concurrently repressing cancer cell-intrinsic proliferation-associated genes and reprogramming the phenotype and subset composition of cancer-associated fibroblasts (CAFs) within the tumor microenvironment. Collectively, our findings indicate the mechanisms of ARNTL in inhibiting ovarian cancer progression and metastasis via the ARNTL-CAFs axis, and provide a promising strategy for ovarian cancer treatment.