Junro Kataoka

Restored expression of the tumor suppressor gene RUNX3 reduces cancer stem cells in hepatocellular carcinoma by suppressing Jagged1-Notch signaling

Runt-related transcription factor 3 (RUNX3) is a candidate tumor suppressor gene that is downregulated in various cancers. In the present study, we analyzed the regulatory function of RUNX3 on Jagged-1 (JAG1) expression and cancer stem cell (CSC) signaling in hepatocellular carcinoma (HCC). Eleven HCC cell lines and 30 human HCC tissues were used. RUNX3 and JAG1 expression levels were analyzed by immunoblotting and immunohistochemistry. Ectopic RUNX3 expression was induced by introducing RUNX3 cDNA into the RUNX3-negative HCC cell line Hep3B and Huh7 cells. Furthermore endogenous RUNX3 expression was knocked down by RUNX3 siRNA in SK-Hep-1 cells. In order to analyze JAG1 transcriptional regulation, we conducted reporter assays, chromatin immunoprecipitation (ChIP) assays and electrophoretic mobility shift assays (EMSAs). Tumorigenicity was analyzed using a SCID mouse liver injection model. An inverse correlation was observed between RUNX3 expression and JAG1 expression in most HCC cell lines and tissues. Restoring RUNX3 expression decreased the expression of JAG1 in Hep3B and Huh7 cells, whereas JAG1 expression was upregulated in RUNX3 siRNA-treated SK-Hep-1 cells. Reporter assays, ChIP assays and EMSAs revealed that RUNX3 directly bound to the transcriptional regulatory region of JAG1 and suppressed JAG1 transcription. Moreover, RUNX3 restoration downregulated CSCs by suppressing JAG1-mediated Notch signaling. The tumorigenic capacity of RUNX3-expressing Hep3B cells was lower compared to that of control Hep3B cells. RUNX3 expression suppressed JAG1 expression and resulted in downregulation of tumorigenesis by suppression of JAG1-mediated CSCs.

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

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 E‐cadherin 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.

Potential of adenovirus-mediated REIC/Dkk-3 gene therapy for use in the treatment of pancreatic cancer

The reduced expression in immortalized cells REIC/the dickkopf 3 (Dkk‐3) gene, tumor suppressor gene, is downregulated in various malignant tumors. In a prostate cancer study, an adenovirus vector carrying the REIC/Dkk‐3 gene (Ad‐REIC) induces apoptosis. In the current study, we examined the effects of REIC/Dkk‐3 gene therapy in pancreatic cancer.

Novel REIC/Dkk-3-encoding adenoviral vector as a promising therapeutic agent for pancreatic cancer

Reduced expression in immortalized cells (REIC)/dickkopf-3 (Dkk-3), a tumor suppressor gene, is downregulated in various cancers. We previously reported the tumor-inhibitory effects of the REIC/Dkk-3 gene, delivered by a conventional adenoviral vector (Ad-CAG-REIC) in pancreatic cancer. Here, we developed an Ad-REIC vector with a novel gene expression system, termed the super gene expression (SGE) system, and assessed its therapeutic effects relative to those of Ad-CAG-REIC in pancreatic cancer cells. Human pancreatic cancer cell lines ASPC1 and MIAPaCa2 were used. REIC/Dkk-3 expression was assessed by western blot analysis. Relative cell viability and apoptotic effects were examined in vitro. The anti-tumor effects of Ad-REIC treatment were assessed in the mouse xenograft model. Compared with Ad-CAG-REIC, Ad-SGE-REIC elicited a significant increase in REIC protein expression in the cells studied. Relative to Ad-CAG-REIC, Ad-SGE-REIC reduced cell viability and induced apoptosis in the ASPC1 and MIAPaCa2 cell lines in vitro, and achieved superior tumor growth inhibition in the mouse xenograft model. Compared with conventional Ad-REIC agents, Ad-SGE-REIC provided enhanced inhibitory effects against tumor growth. Our results indicate that Ad-SGE-REIC is an innovative therapeutic tool for pancreatic cancer.

Synergistic anti‐pancreatic cancer immunological effects by treatment with REIC/DKK3 protein and peripheral blood mononuclear cells

Reduced expression in immortalized cells/dickkopf‐3 (REIC/DKK3) is a reported tumor suppressor gene and has potential to become an innovative therapy for various cancers. We examined the antitumor immunological effects of human REIC/DKK3 protein against pancreatic cancer.

Synergistic anti‐pancreatic cancer immunological effects by treatment with reduced expression in immortalized cells/dickkopf‐3 protein and peripheral blood mononuclear cells

Reduced expression in immortalized cells/dickkopf‐3 (REIC/DKK3) is a reported tumor suppressor gene and has potential to become an innovative therapy for various cancers. We examined the antitumor immunological effects of human REIC/DKK3 protein against pancreatic cancer.

Hepatic stellate cells promote upregulation of epithelial cell adhesion molecule and epithelial-mesenchymal transition in hepatic cancer cells

Microenvironment plays an important role in epithelial-mesenchymal transition (EMT) and stemness of cells in hepatocellular carcinoma (HCC). Epithelial cell adhesion molecule (EpCAM) is known as a tumor stemness marker of HCC. To investigate the relationship between microenvi-ronment and stemness, we performed an in vitro co-culture assay. Four HCC cell lines (HepG2, Hep3B, HuH-7 and PLC/PRF/5) were co-cultured with the TWNT-1 immortalized hepatic stellate cells (HSCs), which create a microenvironment with HCC. Cell proliferation ability was analyzed by flow cytometry (FCM) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphe-nyltetrazolium bromide (MTT) assay, while migration ability was assessed by a wound healing assay. Expression of EpCAM was analyzed by immunoblotting and FCM. HCC cell lines were co-cultured with TWNT-1 treated with small interfering RNA (siRNA) for TGF-β and HB-EGF; we then analyzed proliferation, migration ability and protein expression using the methods described above. Proliferation ability was unchanged in HCC cell lines co-cultured with TWNT-1. Migration ability was increased in HCC cell lines (HepG2, Hep3B, HuH-7 and PLC/PRF/5) directly (216.2±67.0, 61.0±22.0, 124.0±66.2 and 51.5±40.3%) and indirectly (102.5±22.0, 84.6±30.9, 86.1±25.7 and 73.9±29.7%) co-cultured with TWNT-1 compared with the HCC uni-culture. Immunoblot analysis revealed increased EpCAM expression in the HCC cell lines co-cultured with TWNT-1. Flow cytometry revealed that the population of E-cadherin−/N-cadherin+ and EpCAM-positive cells increased and accordingly, EMT and stemness in the HCC cell line were activated. These results were similar in the directly and indirectly co-cultured samples, indicating that humoral factors were at play. Conversely, HCC cell lines co-cultured with siRNA-treated TWNT-1 showed decreased migration ability, a decreased population of EpCAM-positive and E-cadherin−/N-cadherin+ cells. Taken together, humoral factors secreted from TWNT-1 promote upregulation of EpCAM and EMT in hepatic cancer cells.

Loss of Runt-related transcription factor 3 induces resistance to 5-fluorouracil and cisplatin in hepatocellular carcinoma.

Runt-related transcription factor 3 (RUNX3) is known to function as a tumor suppressor in gastric cancer and other types of cancers, including hepatocellular carcinoma (HCC). However, its role has not been fully elucidated. In the present study, we aimed to evaluate the role of RUNX3 in HCC. We used the human HCC cell lines Hep3B, Huh7 and HLF; RUNX3 cDNA was introduced into Hep3B and Huh7 cells, which were negative for endogenous RUNX3 expression, and RUNX3 siRNA was transfected into HLF cells, which were positive for endogenous RUNX3. We analyzed the expression of RUNX3 and multidrug resistance-associated protein (MRP) by immunoblotting. MTT assays were used to determine the effects of RUNX3 expression on 5-fluorouracil (5-FU) and cisplatin (CDDP) sensitivity. Finally, 23 HCC specimens resected from patients with HCC at Okayama University Hospital were analyzed, and correlations among immunohistochemical expression of RUNX3 protein and MRP protein were evaluated in these specimens. Exogenous RUNX3 expression reduced the expression of MRP1, MRP2, MRP3 and MRP5 in the RUNX3-negative cells, whereas knockdown of RUNX3 in the HLF cells stimulated the expression of these MRPs. An inverse correlation between RUNX3 and MRP expression was observed in the HCC tissues. Importantly, loss of RUNX3 expression contributed to 5-FU and CDDP resistance by inducing MRP expression. These data have important implications in the study of chemotherapy resistance in HCC.

Sa1813 The Efficacy of REIC/DKK-3 Gene Therapy for Pancreatic Cancer

cells displayed cytoprotection through crinophagy. The longer gastrin stimulation (months), the more accumulation of lipofuscin bodies, leading to an impaired function and eventually, cell death. The poorly differentiated cells within the ECL cell tumor are probably derived directly or indirectly via runaway autophagy which is associated with anti-apoptotic pathways. We suggest that autophagy-targeted therapy should focus on this runaway pathway in gastrin-driven neoplasia.