Introduction: Radiation fibrosis affects up to half of all patients undergoing radiotherapy for head and neck cancer treatment. It is characterized by excess extracellular matrix deposition, leading to tissue dysfunction, distortion, hardening, and pain. There are currently no effective treatments for radiation fibrosis. A fundamental challenge has been to understand and modulate the function of fibroblasts, a key mediator in extracellular matrix production and degradation. Recent evidence has demonstrated that metabolic regulation plays an important role in altering cell behavior in cancer biology and immunology. However, little is known about how metabolic changes affect fibroblast phenotype.

Hypothesis: We propose that metabolic reprogramming may be an effective strategy to modulate fibroblast function and reduce radiation fibrosis.

Results: An interplay between fatty acid oxidation and glycolysis was found to be a convergence point directly governing fibroblast behavior. It was demonstrated that manipulating the balance between FAO and glycolysis in fibroblasts induced either an extracellular matrix anabolic or catabolic phenotype. Specifically, anabolic fibroblasts relied on a fatty acid oxidation to glycolysis shift to produce extracellular matrix components. Reversal of this metabolic shift generated a catabolic fibroblast, which downregulated extracellular matrix synthesis and upregulated extracellular matrix lysosomal degradation. We further uncovered that CD36, a multifunctional fatty acid transporter, was a crucial link connecting fibroblast metabolism with extracellular matrix regulation, as its depletion completely inhibited collagen-1 internalization and degradation. Finally, through metabolic reprogramming using fibroblasts expressing high levels of CD36, but not CD36 knockout fibroblasts, metabolic balance could be restored, and in turn extracellular matrix accumulation was reduced in murine radiation fibrosis.

Conclusions: We have uncovered that a fibroblast’s phenotype can be differentiated and regulated based on its metabolic signature. These findings have significant implications for drug development and for future cellular therapies to reduce radiation fibrosis.

Citation Format: Xiao Zhao, Pamela Psarianos, David Goldstein, Ralph Gilbert, Ian Witterick, Laurie Ailles, Benjamin Haibe-Kains, Fei-Fei Liu. Utilizing metabolic reprogramming to regulate fibroblast phenotype and reduce radiation fibrosis [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B13.