In hepatocellular carcinoma (HCC) patients with extrahepatic metastasis, the lung is the most frequent site of metastasis. However, how the lung microenvironment favors disseminated cells remains unclear. Here, it is found that nidogen 1 (NID1) in metastatic HCC cell‐derived extracellular vesicles (EVs) promotes pre‐metastatic niche formation in the lung by enhancing angiogenesis and pulmonary endothelial permeability to facilitate colonization of tumor cells and extrahepatic metastasis. EV‐NID1 also activates fibroblasts, which secrete tumor necrosis factor receptor 1 (TNFR1), facilitate lung colonization of tumor cells, and augment HCC cell growth and motility. Administration of anti‐TNFR1 antibody effectively diminishes lung metastasis induced by the metastatic HCC cell‐derived EVs in mice. In the clinical perspective, analysis of serum EV‐NID1 and TNFR1 in HCC patients reveals their positive correlation and association with tumor stages suggesting the potential of these molecules as noninvasive biomarkers for the early detection of HCC. In conclusion, these results demonstrate the interplay of HCC EVs and activated fibroblasts in pre‐metastatic niche formation and how blockage of their functions inhibits distant metastasis to the lungs. This study offers promise for the new direction of HCC treatment by targeting oncogenic EV components and their mediated pathways.
Lipid accumulation exacerbates tumor development, as it fuels the proliferative growth of cancer cells. The role of medium-chain acyl-CoA dehydrogenase (ACADM), an enzyme that catalyzes the first step of mitochondrial fatty acid oxidation, in tumor biology remains elusive. Therefore, investigating its mode of dysregulation can shed light on metabolic dependencies in cancer development. In hepatocellular carcinoma (HCC), ACADM was significantly underexpressed, correlating with several aggressive clinicopathologic features observed in patients. Functionally, suppression of ACADM promoted HCC cell motility with elevated triglyceride, phospholipid, and cellular lipid droplet levels, indicating the tumor suppressive ability of ACADM in HCC. Sterol regulatory element-binding protein-1 (SREBP1) was identified as a negative transcriptional regulator of ACADM. Subsequently, high levels of caveolin-1 (CAV1) were observed to inhibit fatty acid oxidation, which revealed its role in regulating lipid metabolism. CAV1 expression negatively correlated with ACADM and its upregulation enhanced nuclear accumulation of SREBP1, resulting in suppressed ACADM activity and contributing to increased HCC cell aggressiveness. Administration of an SREBP1 inhibitor in combination with sorafenib elicited a synergistic antitumor effect and significantly reduced HCC tumor growth in vivo. These findings indicate that deregulation of fatty acid oxidation mediated by the CAV1/SREBP1/ACADM axis results in HCC progression, which implicates targeting fatty acid metabolism to improve HCC treatment. Significance: This study identifies tumor suppressive effects of ACADM in hepatocellular carcinoma and suggests promotion of β-oxidation to diminish fatty acid availability to cancer cells could be used as a therapeutic strategy.
The complement system is involved in the immunosurveillance of pathogens and tumour cells. Proteomic profiling revealed that extracellular vesicles (EVs) released by metastatic hepatocellular carcinoma (HCC) cells contained a significant number of complement proteins. Complement Factor H (CFH), an abundant soluble serum protein that inhibits the alternative complement pathway, was found to be highly expressed in EVs of metastatic HCC cell lines. Here, we investigated the functional role of EV‐CFH and explored the therapeutic efficacy of targeting EV‐CFH with an anti‐CFH antibody in HCC. The results showed that EVs that are enriched in CFH promoted HCC cell growth, migration, invasiveness and enhanced liver tumour formation in mice. EV‐CFH also promoted metastasis, which was significantly abrogated when treated with an anti‐CFH antibody. These findings demonstrate an unexplored function of EV‐CFH in protecting HCC cells by evading complement attack, thereby facilitating tumorigenesis and metastasis. Lastly, we demonstrated the therapeutic efficacy of an anti‐CFH antibody in suppressing tumour formation in a syngeneic mouse model. This study suggests a new therapeutic strategy for HCC, by inhibiting EV‐CFH with a tumour specific anti‐CFH antibody.
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