Abstract 3082: The liver microenvironment promotes glycolysis in metastatic colorectal cancer by activating her3

Abstract Background: Liver metastasis occurs in ~80% of all metastatic colorectal cancer (mCRC) and the liver has a unique endothelial cell (EC) -rich microenvironment that promotes cancer cell survival. We previously reported that liver ECs secrete soluble factors to promote CRC growth via activating CRC-associated the HER3 signaling pathway. The present study reports that ECs promote mCRC growth by shifting cancer metabolism towards glycolysis and elucidates the involved signaling pathway. Methods: We performed mass spectrometry to profile the metabolic changes in mCRC treated with/without HER3 inhibition in a syngeneic, orthotopic mCRC model. We also performed Seahorse and lactate ELISA assays to determine the effect of liver EC-secreted factors on CRC metabolism. To further determine the role of HER3 in promoting glycolysis and CRC growth in the liver, we used siRNA silencing of HER3 and pharmacological inhibition of HER3 downstream signaling proteins to identify the key mediator (s) of HER3-induced metabolic shift in CRC. Results: We determined that HER3 inhibition leads to increased oxidative phosphorylation metabolites (OXPHOS) and decreased glycolysis metabolites in CRC liver metastases. Conditioned medium containing EC-secreted factors decreased oxygen consumption (determined by Seahorse, a readout of OXPHOS) and increased lactate secretion (determined by ELISA, a readout of glycolysis) in CRC. As HER3 inhibition reversed the metabolic shift and increased OXPHOS as an alternative survival strategy, we found that simultaneous inhibition of HER3 and OXPHOS synergistically blocked CRC cell and tumor growth. Lastly, we found that PFK2 is activated by HER3 signaling, determined by phosphorylation, and determined that the HER3-AKT-PFK2 signaling axis is the key mediator of EC-induced metabolic shifts. Conclusions: We identified that the liver microenvironment activates HER3 and the downstream AKT-PFK2 signaling to promote glycolysis and growth in CRC liver metastases by activating AKT-PFK2-dependent glycolysis. Our findings highlighted the potential of combining HER3 and OXPHOS inhibitions as a potential strategy for treating patients with mCRC. Citation Format: Moeez Ghani Rathore, Kimberly Curry, Christina Boutros, Zhenghe Wang, Jordan Winter, Rui Wang. The liver microenvironment promotes glycolysis in metastatic colorectal cancer by activating her3 abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3082.