Deletion of epithelial HKDC1 decelerates cellular proliferation and impairs mitochondrial function of tumorous epithelial cells thereby protecting from intestinal carcinogenesis in mice
BackgroundA metabolic switch favoring glycolysis over aerobic oxidative phosphorylation, namely the "Warburg effect", represents a hallmark of cancer cells. Hexokinases (HK) catalyze the first step of glycolysis, thereby regulating its rate. Dysregulated HKDC1 (HK domain containing 1) expression has been associated with various cancer types and blocking HKDC1 prevents disease progression for hepatic carcinoma T cell lymphoma and lung adenocarcinoma, but its implication for colorectal cancer (CRC) remained unknown. Here, we functionally investigated the role of HKDC1 for intestinal carcinogenesis. MethodsFirst, we analyzed HKDC1 expression in the intestinal mucosa of healthy controls (HC) and CRC patients and in different tumor tissues using transcriptomic data from publicly available databases. We then generated HKDC1-deficient human and murine colonic epithelial cell lines as well as intestinal organoids and profiled their phenotypic functions. Next, we screened for proteins interacting with HKDC1 by immunoprecipitation. Finally, we generated tumor-bearing ApcMin/+ mice with a conditional deletion of HKDC1 in intestinal epithelial cells and also performed a xenograft mouse model to test the role of HKDC1 for intestinal carcinogenesis in vivo. ResultsHKDC1 was found to be overexpressed in tumor compared to normal tissue of CRC patients. In vitro, HKDC1-deficient human Caco-2 and murine CMT-93 cells displayed reduced proliferation, altered susceptibility to cell death induction, and disrupted mitochondrial functions, particularly mitochondrial respiration. These altered cancer hallmarks were then corroborated in HKDC1-deficient normal and tumor-derived ApcMin/+ intestinal organoids. Immunoprecipitation and mass spectometry proteomic analyses revealed interactions of HKDC1 with several mitochondria-related proteins. In vivo, two distinct mouse models demonstrated that epithelial deletion of HKDC1 protected from carcinogenesis. First, ApcMin/+-Hkdc1{Delta}IEC mice showed mildly improved disease phenotypes in the colon accompanied with reduced numbers of Ki67-positive proliferating epithelial cells. Finally, HKDC1-deficient Caco-2 cells completely failed to form any tumor mass in a xenograft model when implanted into immunodeficient mice. ConclusionsWe demonstrate that HKDC1 influences cancer cell proliferation and susceptibility to cell death, potentially through interactions with mitochondrial proteins that regulate membrane permeability, ultimately impacting intestinal carcinogenesis. Collectively, these findings highlight the significance of HKDC1 for CRC pathobiology, presenting it as a promising target for further investigation and potential therapeutic interventions.