The cellular entry of Hantaan virus (HTN) occurs through interactions with β3 integrins as cellular receptors. However, the process of HTN infection following attachment to the cell surface is not ...well understood. Our data indicate that overexpression of a dominant-negative mutant dynamin inhibits HTN internalization and that compounds that block clathrin- but not caveolae-dependent endocytosis also reduce HTN infectivity. In addition, we show that HTN colocalizes with the clathrin heavy chain but not with caveolae. At the early phase of infection HTN colocalizes with EEA-1, an early endosome marker, and later, HTN colocalizes with LAMP-1, a lysosome marker. Cells treated with lysosomotropic agents are largely resistant to infection, suggesting that a low-pH-dependent step is required for HTN infection. These findings demonstrate that HTN enters cells via the clathrin-coated pit pathway and uses low-pH-dependent intracellular compartments for infectious entry.
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•Brusatol affects migration and invasion ability of HCC cells.•Brusatol affects EMT process through modulation of STAT3 activation pathway.•Brusatol mitigates tumorigenesis and ...metastasis in HCC preclinical model.
Epithelial-mesenchymal transition (EMT) is a process of transdifferentiation where epithelial cells attain mesenchymal phenotype to gain invasive properties and thus, can contribute to metastasis of tumor cells.
The antimetastatic and antitumor efficacy of brusatol (BT) was investigated in a hepatocellular carcinoma (HCC) model.
We evaluated the action of BT on EMT process using various biological assays in HCC cell lines and its effect on tumorigenesis in an orthotopic mouse model.
We found that BT treatment restored the expression of Occludin, E-cadherin (epithelial markers) while suppressing the levels of different mesenchymal markers in HCC cells and tumor tissues. Moreover, we observed a decline in the expression of transcription factors (Snail, Twist). Since the expression of these two factors can be regulated by STAT3 signaling, we deciphered the influence of BT on modulation of this pathway. BT suppressed the phosphorylation of STAT3Y705 and STAT3 depletion using siRNA resulted in the restoration of epithelial markers. Importantly, BT (1mg/kg) reduced the tumor burden in orthotopic mouse model with a concurrent decline in lung metastasis.
Overall, our results demonstrate that BT interferes with STAT3 induced metastasis by altering the expression of EMT-related proteins in HCC model.
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