Crosstalk Between RARγ-Driven Tumor Cells and Cancer-Associated Fibroblasts Governs Ferroptosis Resistance in Cholangiocarcinoma.

Abstract

Cholangiocarcinoma (CCA) is characterized by a dense desmoplastic microenvironment dominated by cancer-associated fibroblasts (CAFs), which profoundly shape tumor behavior and diminish therapeutic efficacy. By integrating analyses of patient specimens with multi-omics profiling, mechanistic assays, tumor-CAF co-culture and xenograft models, and single-cell transcriptomics, we identified retinoic acid receptor γ (RARγ) as a central regulator of reciprocal communication between malignant cells and CAFs that promotes ferroptosis resistance. RARγ was markedly elevated in CAF-enriched tumors and associated with poor overall survival. Multi-omics integration revealed that RARγ increases CREB stability and reduces K33- and K48-linked polyubiquitination, thereby enhancing CREB occupancy at the AKR1C1 promoter and driving transcriptional activation. AKR1C1 subsequently reinforces the Nrf2-GPX4 antioxidant axis, elevates glutathione metabolism, and suppresses lipid peroxidation. Beyond intrinsic protection, RARγ induces LCN2 transcription and promotes exosomal packaging of LCN2, which is transferred to adjacent CAFs and triggers robust CSF3 (G-CSF) secretion. CAF-derived G-CSF feeds back to malignant cells to amplify RARγ expression and ferroptotic tolerance, forming a self-sustaining paracrine circuit. Single-cell RNA sequencing further supported coordinated interactions between RARG+ tumor subsets and CSF3+ CAFs, reinforcing the relevance of this signaling loop in human CCA. Collectively, these findings position RARγ as a master organizer of tumor-stroma crosstalk through the CREB-AKR1C1 and LCN2-CSF3 axes, establishing a ferroptosis-resistant niche and promoting CCA aggressiveness.

Key Findings

• RARγ is elevated in cancer-associated fibroblast (CAF)-enriched cholangiocarcinoma tumors and correlates with poor overall survival.
• RARγ enhances CREB stability, leading to increased AKR1C1 transcription, which reinforces the Nrf2-GPX4 antioxidant axis, elevates glutathione metabolism, and suppresses lipid peroxidation, promoting ferroptosis resistance.
• RARγ induces LCN2 expression and exosomal transfer to CAFs, triggering CAF secretion of G-CSF, which in turn amplifies RARγ expression and ferroptotic tolerance in tumor cells, creating a self-sustaining paracrine circuit.

Clinical Significance

Citation

Li Si-Yang, Liu Fa-Hui, Shang Jinet al.. Crosstalk Between RARγ-Driven Tumor Cells and Cancer-Associated Fibroblasts Governs Ferroptosis Resistance in Cholangiocarcinoma. Cancer letters. 2026-Nov-06.