HKDC1 reprograms lipid metabolism to enhance gastric cancer metastasis and cisplatin resistance via forming a ribonucleoprotein complex

As essential modulators of transcription and translation, RNA-binding proteins (RBPs) are frequently dysregulated in cancer. Bioinformatics study reveals that the RNA-binding protein hexokinase domain component 1 (HKDC1) is overexpressed in gastric cancer (GC). As HKDC1 plays a role in lipid homeostasis in the liver and glucose metabolism in certain cancers, the exact mechanism of action of HKDC1 in GC remains largely unknown. Upregulation of HKDC1 correlates with chemoresistance and poor prognosis in GC patients. HKDC1 enhances invasion, migration and resistance to cisplatin (CDDP) in GC cells in vitro and in vivo. Comprehensive transcriptomic sequencing and metabolomic analysis reveal that HKDC1 mediates abnormal lipid metabolism in GC cells. Herein, we identify a number of HKDC1-binding endogenous RNAs in GC cells, including protein kinase, DNA-activated, catalytic subunit (PRKDC) mRNA. We further validate that PRKDC is a crucial downstream effector of HKDC1 induced-GC tumorigenesis depends on lipid metabolism. Interestingly, G3BP1, a well-known oncoprotein, can be bound by HKDC1. HKDC1 cooperates with G3BP1 to enhance the stability of PRKDC transcript. Our results reveal a novel HKDC1/G3BP1-PRKDC regulatory axis that induces GC metastasis and chemoresistance via reprogramming lipid metabolism, which may provide an effective therapeutic strategy for a subset of GC with HKDC1 overexpression.