Abstract 1535: Glycogen metabolism is critical for cancer-associated fibroblast proliferation and immunosuppressive activity

Background: Metabolic reprogramming is a characteristic feature of both cancer cells and their neighboring cells in the immunosuppressive tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are the major sources of secreted cytokines contributing to the immunosuppressive activity in the TME. Dysregulation of glycogen metabolism is integral to cancer cell proliferation and metastasis. The purpose of this study was to identify whether glycogen metabolism is important for CAF proliferation and cytokine production. Methods: CAFs were isolated from colorectal cancer (CRC) patient samples and cultured in conditioned medium (CM) derived from HCT116 human CRC cells. The expression of glycogen phosphorylase liver form (PYGL), glycogen phosphorylase brain form (PYGB), hexokinase 2 (HK2), lactate dehydrogenase A (LDHA), IL6, CLCF1, LIF, and CXCL6 was determined by either real time (RT)-PCR or western blot. Glycogen levels were determined using a Glycogen Analysis Kit. Cell proliferation was determined using WST-1. Results: (i) Data set analysis identified an elevated glucose metabolism in CAFs compared to normal fibroblasts. (ii) Treatment of CAFs with CM derived from HCT116 cells resulted in activated glycogen metabolism as noted by elevated protein expression of glycogen synthase, PYGL, PYGB, and the reduced level of glycogen in CAFs. In addition, CM increased glucose metabolism in CAFs as noted by significantly increased expression of HK2 and LDHA. Moreover, CM increased the expression of IL6 family cytokines such as IL6, CLCF1, LIF and CXCL6 in CAFs. (iii) Inhibition of glycogen metabolism by treatment with the PYG inhibitor, CP-91149, significantly repressed CAF proliferation and reduced the expression of these cytokines. Consistently, knockdown of PYGB or PYGL significantly decreased the level of these cytokines in CAFs. (iv) Inhibition of glycogen synthase by treatment with the glycogen synthase inhibitor, MZ-101, or knockdown of glycogen synthase 1 decreased the expression of these cytokines in CAFs. Conclusion: Our results demonstrate that glycogen metabolism is crucial for promoting CAF proliferation and cytokine production. Importantly, our findings suggest that targeting glycogen metabolism in CAFs reshapes the immunosuppressive TME and may enhance the efficacy of immunotherapy for CRC. Citation Format: Xudong Zhu, Yuning Zhou, Zhijie Yin, Jinpeng Liu, Chi Wang, B.Mark Evers, Qingding Wang. Glycogen metabolism is critical for cancer-associated fibroblast proliferation and immunosuppressive activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1535.