DLC3 expression in hepatocellular carcinoma

Introduction and objective: Deleted in Liver Cancer (DLC) proteins belong to the family of RhoGAPs and thus are believed to operate as negative regulators of the Rho family of small GTPases. Rho proteins are considered to be significant links between numerous cellular pathways. So far, DLC1 – the first identified member from Deleted in Liver Cancer family – has been established as a tumour suppressor in hepatocellular carcinoma. As shown by many studies, DLC1 expression is reduced by gene loss or epigenetic silencing in this type of cancer. The expression and function of its close family relative DLC3 is less known. The presented study determined the expression and cellular localization of DLC3 protein in hepatocellular carcinoma tissue. Material and Methods: The protein level in two types of hepatocellular carcinoma: typical and fibrolamellar, were assessed by the immunohistochemical approach. Results: DLC3 immunoreactivity was found to be present in the cytoplasm of normal hepatocytes. In hepatocellular carcinoma sections, DLC3 was detected primarily in the cytoplasm of cancer cells, although in a small percentage of cancer cells cell nuclei were also positively stained. Morphometric analysis followed by statistical evaluation showed that the DLC3 immunoreactivity in the tumour sections was comparable to the one observed in non-cancerous liver specimens. Conclusions: The results obtained indicate that DLC3 protein, contrary to DLC1, is commonly expressed in hepatocellular carcinoma. It appears that members of the DLC family, although structurally highly related, may function differently during HCC development.