Runt‐related transcription factor 3 reverses epithelial–mesenchymal transition in hepatocellular carcinoma

Abstract

Loss or decreased expression of runt-related transcription factor 3 (RUNX3), a tumor suppressor gene involved in gastric and other cancers, has been frequently observed in hepatocellular carcinoma (HCC). The objective of this study was to identify the regulatory mechanism of the epithelial-mesenchymal transition (EMT) by RUNX3 in HCC. Human HCC cell lines, Hep3B, Huh7, HLF and SK-Hep1, were divided into low-and high-EMT lines, based on their expression of TWIST1 and SNAI2, and were used in this in vitro study. Ectopic RUNX3 expression had an anti-EMT effect in low-EMT HCC cell lines characterized by increased Ecadherin expression and decreased N-cadherin and vimentin expression. RUNX3 expression has previously been reported to reduce jagged-1 (JAG1) expression; therefore, JAG1 ligand peptide was used to reinduce EMT in RUNX3-expressing low-EMT HCC cells. Immunohistochemical analyses were performed for RUNX3, E-cadherin, N-cadherin and TWIST1 in 33 human HCC tissues, also divided into low-and high-EMT HCC, based on TWIST1 expression. E-cadherin expression was correlated positively and N-cadherin expression was correlated negatively with RUNX3 expression in low-EMT HCC tissues. Correlations between EMT markers and RUNX3 mRNA expression were analyzed using Oncomine datasets. Similarly, mRNA expression of E-cadherin was also significantly correlated with that of RUNX3 in low-EMT HCC, while mRNA expression of JAG1 was negatively correlated with that of RUNX3. These results suggest a novel mechanism by which loss or decreased expression of RUNX3 induces EMT via induction of JAG1 expression in low-EMT HCC.

RUNX3 regulates vimentin expression via miR‐30a during epithelial–mesenchymal transition in gastric cancer cells

“…Tanaka et al . 35 also found that RUNX3 reversed the EMT in hepatocellular carcinoma, but the mechanism underlying RUNX3 action is different in gastric cancer cells. Tanaka et al .…”

“…Tanaka et al . 35 showed that ectopic RUNX3 protein expression induced E-cadherin expression and suppressed vimentin expression in hepatocellular carcinoma cells with low EMT. However, in our study, RUNX3 did not induce E-cadherin in human gastric cancer cells.…”

The Notch ligand Jagged1 as a target for anti-tumor therapy

“…A role in EMT has also been described in cervical cancer, where JAG1 expression correlates with the rapid induction of phosphoinositol-3-kinase (PI3K)-mediated EMT (67); in hepatocellular carcinoma where it is repressed by the tumor-suppressor RUNX3 (68); and in treatment-resistant pancreatic cancer cells, where the JAG1-Notch2 axis controls several EMT transcription factors such as SNAIL, SLUG, and ZEB1 (69). Pro-invasive, migratory, and metastatic function has been also demonstrated for prostate cancer, where high JAG1 expression has been clinically linked to metastasis development and regulation of migration/invasion via NF-κB (70, 71), and for colon cancer, where it mediates APEX1 pro-tumorigenic functions and induces the metastasis markers MMP-2 and MMP-9 (72, 73).…”

Human hepatocyte carcinogenesis

“…RUNX3 is a potential tumor suppressor gene for HCC, as the decreased mRNA expression of RUNX3 was observed in 50–92% of HCC cases (31,32). The significance of decreased expression of RUNX3 is related to dysfunction of cell cycle regulation, decrement of apoptosis (33,34), enhancement of angiogenesis, and the development of epithelial-mesenchymal transition (35). …”