Augmenter of Liver Regeneration (ALR) which is critically important in liver regeneration and hepatocyte proliferation is highly expressed in cirrhotic livers and hepatocellular carcinomas (HCC). In the current study the functional role of ALR in hepatocancerogenesis was analysed in more detail. HepG2 cells in which the cytosolic 15 kDa ALR isoform was stably re-expressed (HepG2-ALR) were used in migration and invasion assays using modified Boyden chambers. Epithelial-mesenchymal transition (EMT) markers were determined in HepG2-ALR cells in vitro and in HepG2-ALR tumours grown in nude mice. ALR protein was quantified in HCC and non-tumorous tissues by immunohistochemistry.HepG2-ALR compared to HepG2 cells demonstrated reduced cell motility and increased expression of the epithelial cell markers E-cadherin and Zona occludens-1 (ZO-1) whereas SNAIL, a negative regulator of E-cadherin, was diminished. Matrix metalloproteinase MMP1 and MMP3 mRNA expression and activity were reduced. HepG2-ALR cell derived subcutaneously grown tumours displayed less necrotic areas, more epithelial-like cell growth and less polymorphisms and atypical mitotic figures than tumours derived from HepG2 cells. Analysis of tumour tissues of 53 patients with HCC demonstrated an inverse correlation of ALR protein with histological angioinvasion and grading. The 15 kDa ALR isoform was mainly found in HCC tissues without histological angioinvasion. In summary the present data indicate that cytosolic ALR reduces hepatoma cell migration, augments epithelial growth, and therefore, may act as an anti-metastatic and EMT reversing protein.
