HMGB1 promotes mitochondrial transfer between hepatocellular carcinoma cells through RHOT1 and RAC1 under hypoxia

Abstract

Abstract Background Mitochondrial transfer has been found to play an important role in various diseases, and many mitochondrial biological behaviors can be regulated by HMGB1. However, the role of mitochondrial transfer in HCC and its relationship with HMGB1 are currently unknown. Method Field emission scanning electron microscope, immunofluorescence, and cell flow cytometry were used to detect mitochondrial transfer between HCC cells. Analyze the change and significance of related molecules in clinical samples of HCC through bioinformatics analysis and tissue microarrays. The specific mechanism was determined by co-immunoprecipitation, luciferase reporter assay and chromatin immunoprecipitation. Cell metastasis and invasion ability were detected through in vitro cell migration and invasion analysis, as well as in vivo tail vein lung metastasis in mice. Result We confirmed the transfer of mitochondria between HCC cells through tunnel nanotubes. The transfer of mitochondria from the higher invasive HCC cells to the lower invasive HCC cells could enhance the migration and invasion ability of the latter, and the hypoxic conditions increased the mitochondria transfer between HCC cells. During this process, RHOT1, as the mitochondrial transport protein, promoted mitochondrial transfer and promoted the migration and metastasis of HCC cells. Under hypoxia, HMGB1 further regulated the expression of RHOT1 by increasing the expression of NFYA and NFYC subunits in the NF-Y complex. RAC1, as the protein associated with the formation of tunnel nanotubes, promoted mitochondrial transfer and also promoted the development of HCC. Besides, HMGB1 regulated RAC1 aggregation to the cell membrane under hypoxia. In clinical samples, patients with high expression of HMGB1, RHOT1, or RAC1 in HCC had the relatively shorter overall survival period. Conclusion Under hypoxic conditions, HMGB1 promotes mitochondrial transfer and migration and invasion of HCC cells by increasing the expression of mitochondrial transport protein RHOT1, as well as the expression of tunnel nanotube formation related protein RAC1.