Liver cancer has a poor prognosis predominantly resulting from tumour heterogeneity and limited treatment options. The two predominant types of liver cancer are Hepatocellular carcinoma (HCC) and Intrahepatic Cholangiocarcinoma (iCCA). CD44v6, a splice variant of the hyaluronic acid receptor CD44, is a marker for cancer stem cells, and is known to impact tumour formation and metastasis in several cancers. The expression of CD44v6 dramatically increases in liver epithelial cells upon carcinogen exposure. With this study, we aim to target CD44v6 in primary human liver carcinoma cell lines by using a small peptide inhibitor, and observe the effects of CD44v6 inhibition on migration, invasion and EMT.
CD44v6 expression was investigated in mouse and human liver and tumour tissue by immunohistochemistry. In addition, we used human HCC and CC cell lines to study the role of CD44v6 inhibition on cell migration, invasion and EMT.
We observed CD44v6+ epithelial cells in premalignant livers of transgenic mouse models with chronic liver damage. The expression patterns of CD44v6+ cells differed in the mouse models, where the cells had a hepatocyte-like phenotype in some mouse models and a cholangiocyte-like phenotype in others. Deletion of Trp53 in the liver resulted in a significant increase in the number of CD44v6+ cells. CD44v6 expression was also increased in murine and human tumours compared to the liver, and coincided with Sox9 expression in murine tumours. Human liver cancer cell lines were analysed for CD44 expression and two CC cell lines were found to have high expression of CD44 (85-90%). Functional assays (clonogenic assay, wound healing assay and transwell migration assay) were performed using the CC cell lines. Treatment with AMC303 conferred a reduction in the migration potential of cells in CC cell lines. Inhibition of CD44v6 also resulted in a reduction in the colony formation potential of the cells, indicating a decrease in the stemness characteristics of the cells. A reduction in EMT in both 2D and 3D culture was also observed.
Inhibition of CD44v6 in liver cancer cell lines led to a reduction in chemotaxis, migration, EMT and the stemness characteristics of cells. In summary, CD44v6 appears to be a promising targetable candidate for liver carcinoma.
The authors.
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All authors have declared no conflicts of interest.