ILEI requires oncogenic Ras for the epithelial to mesenchymal transition of hepatocytes and liver carcinoma progression

Abstract

In human hepatocellular carcinoma (HCC), epithelial to mesenchymal transition (EMT) correlates with aggressiveness of tumors and poor survival. We employed a model of EMT based on immortalized p19 ARF null hepatocytes (MIM), which display tumor growth upon expression of oncogenic Ras and undergo EMT through the synergism of Ras and transforming growth factor (TGF)-b. Here, we show that the interleukin-related protein interleukin-like EMT inducer (ILEI), a novel EMT-, tumor-and metastasis-inducing protein, cooperates with oncogenic Ras to cause TGF-b-independent EMT. Ras-transformed MIM hepatocytes overexpressing ILEI showed cytoplasmic E-cadherin, loss of ZO-1 and induction of a-smooth muscle actin as well as plateletderived growth factor (PDGF)/PDGF-R isoforms. As shown by dominant-negative PDGF-R expression in these cells, ILEI-induced PDGF signaling was required for enhanced cell migration, nuclear accumulation of b-catenin, nuclear pY-Stat3 and accelerated growth of lung metastases. In MIM hepatocytes expressing the Ras mutant V12-C40, ILEI collaborated with PI3K signaling resulting in tumor formation without EMT. Clinically, human HCC samples showed granular or cytoplasmic localization of ILEI correlating with well and poorly differentiated tumors, respectively. In conclusion, these data indicate that ILEI requires cooperation with oncogenic Ras to govern hepatocellular EMT through mechanisms involving PDGF-R/b-catenin and PDGF-R/ Stat3 signaling.

Down-regulation of CMTM8 Induces Epithelial-to-Mesenchymal Transition-like Changes via c-MET/Extracellular Signal-regulated Kinase (ERK) Signaling

“…Unlike the results obtained with expression of activated RasV12, CMTM8 knockdown did not elevate the expression of ␣-smooth muscle actin (data not shown), which is a mesenchymal marker reported for EMT in hepatocyte-originated cell models (35). This difference may be due to incomplete knockdown with the available CMTM8 siRNAs, which are not capable of maintaining full knockdown during the course of extended EMT experiments.…”

“…We first tested the expression of EMT markers by indirect immunofluorescence and Western blotting. E-cadherin is an epithelial marker that functions in epithelial cell-cell adhesion and is down-regulated or mislocalized both in EMT cell models and at the invasive edge of some human tumor biopsies (2,15,16,34,35). In HepG2 cells with CMTM8 knockdown, E-cadherin was indeed down-regulated, which was verified by both immunofluorescence (Fig.…”

The FAM3 superfamily member ILEI ameliorates Alzheimer’s disease-like pathology by destabilizing the penultimate amyloid-β precursor

“…Earlier works have revealed that ILEI acts downstream of TGF-b to induce epithelial-to-mesenchymal transition of epithelial cells, whereas PANDER, which is cosecreted with insulin from pancreatic islet cells, is involved in regulation of insulin secretion and glycemic levels 28,36,37 . Expression of the ILEI transcript in human brain has been described 22 .…”

Epithelial-mesenchymal transitions and hepatocarcinogenesis

“…Elevated expression of another EMT mediator, integrin-linked kinase (ILK), identifies hepatoma cell lines that are resistant to epidermal growth factor receptor-targeted therapies, and knocking down ILK restores sensitivity to these agents (21). EMT is also induced in neoplastic hepatocytes by TGF-β, IL-like EMT inducer (ILE1), and oncogenic Ras interactions that promote distant metastasis (22). Similarly, ectopic expression of Twist or Snail in hepatoma cell lines with low endogenous expression of these factors enhances cancer cell motility and invasiveness (12,17).…”