Discoidin Domain Receptor 1 Promotes Hepatocellular Carcinoma Progression Through Modulation Of SLC1A5 And The MTORC1 Signaling Pathway

Objective: Hepatocellular carcinoma(HCC)has poor prognosis and high mortality,and is one of the leading cancers in the world.Therefore,further study and understanding of the molecular mechanisms of hepatocellular carcinoma progression can provide important insights into our treatment and management of hepatocellular carcinoma.Receptor tyrosine kinases(RTKs)play an important role in the occurrence and development of various cancers,and discoidin domain receptor 1(DDR1)is a trans-Membrane RTK.Methods: Western blotting and immunohistochemical staining were used to detect the protein level of DDR1 in liver cancer cell lines and primary liver cancer patient samples;we overexpressed and knocked down DDR1 according to the expression level of DDR1 in each cell line To detect the effect of DDR1 on tumor proliferation.We explored the effect of DDR1 on tumor proliferation using CCK8 and clonogenic assays,and cell cycle assays using flow cytometry.Mechanistically,we discovered a protein that binds to DDR1 by liquid chromatography-mass spectrometry(LC-MS).To explore how DDR1 affects the stability of SLC1A5,we pretreated liver cancer cell lines overexpressing or knocking down DDR1 with a protein synthesis inhibitor(CHX).At the same time,we used proteasome inhibitor(Mg132)and lysosome inhibitor(NH4Cl)to pretreat the cells to detect the regulation mode.We also detected the expression of SLC1A5 in hepatocellular carcinoma patient samples by western blotting and immunohistochemistry.Results: The expression of DDR1 was significantly increased in HCC by western blotting and immunohistochemical staining,and was associated with poor clinical prognosis.In addition,DDR1 can affect the proliferation rate of HCC tumor cells both in vivo and in vitro,and we also found that the loss or increase of DDR1 expression affects the HCC cell cycle progression.Furthermore,DDR1 affects the stability of SLC1A5 through a lysosomal protein degradation pathway.Histochemical and Western blotting experiments proved that there is a correlation between DDR1 and SLC1A5 protein expression.Conclusion: The study revealed a new mechanism by which DDR1 plays a role in promoting hepatocellular carcinoma,and DDR1 expression can be used as an independent prognostic marker for hepatocellular carcinoma.The protein expression levels of DDR1 and SLC1A5 were positively correlated in clinical samples.Our findings provide a new perspective for understanding the development of HCC and provide new ideas for the treatment and management of HCC.