Interferon-Dependent Cancer-Associated Fibroblasts Render the Responsiveness of Neoadjuvant Radiotherapy in Colorectal Cancer.

The response to neoadjuvant radiotherapy (RT) in colorectal cancer (CRC) patients is compromised partially due to the plasticity and heterogeneity of cancer-associated fibroblasts (CAFs). However, the underlying mechanisms remain unclear. Our study aims to unravel the cues instigating and sustaining distinctive RT induced CAFs subpopulation within the tumor microenvironment (TME) and explores strategies for the repolarization of this CAFs. The hypothesis of this study is that Interferon-dependent CAFs (irCAFs) promote RT-Induced anti-tumor immunity through the interferon gamma (IFN-γ) / signal transducer and activator of transcription 1(STAT1) Pathway in colorectal cancer. To comprehensively unravel the cellular intricacies of CAFs and intercellular interactions in CRC patients post-RT, we using single-cell RNA sequencing, multiparametric flow cytometry, and multiplexed immunofluorescence staining to identified a subpopulation of irCAFs. To probe the functionality of irCAFs and unravel the underlying mechanisms, we established three preclinical CRC models (MC38 syngeneic tumor-bearing mice, autochthonous APCmin/+ CRC tumors and Azoxymethane (AOM)/Dextran sodium sulfate (DSS) induced colitis-associated cancer (CAC) models.) for in vivo monitoring of the effects of RT. In this study, utilizing single-cell RNA sequencing of CRC patient samples, we identified a subpopulation of CAFs characterized by the overexpression of interferon regulatory factor 1 (IRF1). The enrichment of these IRF1-expressing CAFs (irCAFs) enhances RT responses in various solid tumors, including CRC. Mechanistically, IFN-γ signaling induces irCAFs polarization, and recruits T and dendritic cells through CCL4/CCL5 secretion. The activation of IFN-γ/STING signaling leads to stromal reprogramming and augments anti-tumor immunity in both RT-sensitive and resistant CRC tumors. Inhibiting the enrichment of irCAFs by STING silencing in CAFs reduces the vulnerability of tumors to RT. Combining STING agonists with RT results in robust tumor control, providing a compelling rationale for testing this therapeutic strategy in clinical trials. Cumulatively, our findings emphasize the translational potential of combining STING agonists with radiation therapy, warranting exploration in additional clinical settings, particularly in patients who have developed resistance to radiotherapy. [ABSTRACT FROM AUTHOR]