Sun Kyo Song

Relationship between Urokinase-Type Plasminogen Receptor, Interleukin-8 Gene Expression and Clinicopathological Features in Gastric Cancer

Objective: The serine protease urokinase-type plasminogen (uPA) and its receptor (uPAR) appear to have a major function in tumor invasion and metastasis. Interleukin-8 (IL-8) acts as an angiogenic factor in solid cancer. The purpose of this study was to determine whether the expression of IL-8 and the uPAR gene correlates with clinicopathological parameters in human gastric carcinoma. Methods: We examined the expression of uPAR mRNA and IL-8 mRNA using Northern blot analysis and RT-PCR in 35 gastric carcinomas and the surrounding normal mucosa. Macroscopic and histopathological tumor findings and survival rates were obtained from the patient records. Results: uPAR and IL-8 mRNA expression levels were higher in most neoplasms compared to the corresponding normal mucosal tissue. A correlation between uPAR and IL-8 expression in tumors was observed (r = 0.447, p < 0.01). uPAR mRNA expression in the tumors correlated well with lymph node metastasis (p < 0.02), and its stage (p < 0.01). The IL-8 MRNA expression in the tumors correlated with diffuse-type gastric cancer (p < 0.05). The survival rates of patients with tumors displaying high uPAR expression levels were significantly lower (p < 0.04) than those of patients without uPAR expression, but patients with IL-8 expression only showed a tendency to a lower survival rate. Conclusion: These results suggest that uPAR and IL-8 may be important prognostic factors in human gastric carcinomas.

Hepatoma-derived growth factor regulates the bad-mediated apoptotic pathway and induction of vascular endothelial growth factor in stomach cancer cells.

Hepatoma-derived growth factor (HDGF) is highly expressed in tumor cells and may play an important role in the development and progression of carcinomas. However, the molecular mechanism by which HDGF participates in gastric carcinomatosis requires further analysis. In this study, we determined the role of HDGF in tumorigenesis and elucidated the mechanisms of action. To determine aggressive biological behavior, we knocked down HDGF expression with HDGF-specific shRNA in two gastric cancer cell lines. First, using cDNA microarrary, we showed that hepatocyte growth factor (HGF) induced HDGF and confirmed this by Western blotting. HGF increased HDGF in a dose-dependent manner. We also determined whether HDGF induces angiogenic factor, and found the vascular endothelial growth factor (VEGF) was induced by HDGF. Downregulation of HDGF resulted in a decrement of VEGF. HDGF knock-down was found to induce the expression of the proapoptotic protein, Bad, and also inactivate ERK, which in turn led to dephosphorylation of Bad at ser112 and ser136, and induced apoptosis. Transfection with HDGF-siRNA resulted in a decrement of cell proliferation, as determined with a MMT assay. In an in vitro invasion assay, significantly fewer cells transfected with HDGF-siRNA than control cells were able to invade across a Matrigel membrane barrier. Our results suggest that HDGF is involved in cell growth, cell invasion, and apoptosis. These qualities may contribute to the HDGF-associated aggressive biological behavior of gastric cancer and thus serve as a potential target for cancer therapy.

Inhibition of histone deacetylase activity down-regulates urokinase plasminogen activator and matrix metalloproteinase-9 expression in gastric cancer

Histone acetylation and deacetylaion play important roles in chromatin remodeling and gene expression. An imbalance of these reactions leads to aberrant behavior of the cells in the cell cycle, which in turn contributes to carcinogenesis. Histone deacetylase (HDAC) inhibitors have been shown to have anti-tumor effects in clinical trials. However, the exact mechanisms by which HDAC inhibitors exert anti-tumor effects and modulate gene expression are not completely understood, and remain a subject of intense investigation. In the current study, we determined whether HDACs regulate urokinase plasminogen activator (uPA), matrix metalloproteinase-9 (MMP-9), and tumor invasion. Using cDNA microarray analysis, we found that hepatocyte growth factor (HGF) induced HDAC5 expression in gastric cancer cell lines, NUGC-3 and MKN-28. TSA, a HDAC inhibitor, decreased HGF-induced HADC-5 expression and also repressed uPA and MMP-9 expression. TSA inhibited cell proliferation in both cell lines. In vitro Matrigel invasion assays showed that the HDAC inhibitor decreased cancer cell invasion. Furthermore, GO6976, a PKC inhibitor, significantly inhibited not only HGF-induced HDAC5 expression but also cell invasion. These results demonstrated that HDACs regulate HGF-induced uPA and MMP-9 expression through a PKC-dependent signal pathway in gastric cancer cells. Our data probably suggest that such activities serve as anti-tumor mechanisms of the HDAC inhibitor.

Regulation of hepatocyte growth factor-mediated urokinase plasminogen activator secretion by MEK/ERK activation in human stomach cancer cell lines

The regulatory mechanisms for the proliferation and the particular invasive phenotypes of stomach cancers are not still fully understood. Up-regulations of hepatocytes growth factor (HGF), its receptor (c-Met), and urokinase-type plasminogen activator (uPA) are correlated with the development and metastasis of cancers. In order to investigate roles of HGF/c-Met signaling in tumor progression and metastasis in stomach cancers, we determined effects of a specific MEK1 inhibitor (PD098059) and a p38 kinase inhibitor (SB203580) on HGF-mediated cell proliferation and uPA expression in stomach cancer cell lines (NUGC-3 and MKN-28). HGF treatment induced the phosphorylations of ERK and p38 kinase in time- and dose- dependent manners. Pre-treatment with PD098059 reduced HGF-mediated cell proliferation and uPA secretion. In contrast, SB203580 pre-treatment enhanced cell proliferation and uPA secretion due to induction of ERK phosphorylation. Stable expression of dominant negative-MEK1 in NUGC-3 cells showed a decrease in HGF-mediated uPA secretion. These results suggest that interaction of a MEK/ERK and a p38 kinase might play an important role in proliferation and invasiveness of stomach cancer cells.

Hepatocyte growth factor/c-met signaling in regulating urokinase plasminogen activator in human stomach cancer: A potential therapeutic target for human stomach cancer.

Background Up-regulation of the hepatocyte growth factor (HGF), its transmembrane tyrosine kinase receptor (c-Met), and urokinase type plasminogen activator (uPA), is associated with the development and metastasis of various types of cancers. However, the mechanisms by which HGF/c-Met signaling mediates cancer progression and metastasis are unclear. Methods We investigated the roles of HGF/c-Met in tumor progression and metastasis in NUGC-3 and MKN-28 stomach cancer cell lines. Results Treatment with HGF increased c-Met phosphorylation in a dose-dependent manner, as well as increasing cell proliferation. HGF treatment also increased the protein level and the activity of uPA in NUGC-3 and MKN-28 cells. A monoclonal antibody against human uPA receptor (uPAR), mAb 3936, inhibited HGF-mediated tumor cell invasion in a dose-dependent manner. Down-regulation of uPA using uPA-shRNA induced a decrease in in vitro cell invasion in NUGC-3 cells. Conclusions These results suggest that NUGC-3 and MKN-28 cells express functional c-Met, which may provide a therapeutic target for interfering with metastases of cancer cells by inhibiting uPA and uPAR-mediated proteolysis.

The efficacy of docetaxel and cisplatin combination chemotherapy for the treatment of advanced gastric cancer after failing to 5-fluorouracil based chemotherapy.

PURPOSE This study was conducted to confirm the efficacy and toxicity of docetaxel and cisplatin combination chemotherapy (DP) in patients with advanced gastric cancer. MATERIALS AND METHODS Patients with measurable gastric adenocarcinoma received intravenous docetaxel 75 mg/m(2) and cisplatin 75 mg/m(2) with premedication on day 1, which was repeated every 3 weeks. All patients received DP as a second-line treatment after failing to 5-FU based chemotherapy. RESULTS 34 patients were enrolled in this study between January 1998 and August 2003. A total of 112 cycles (median 3 cycles) were administered. Responses were evaluable in 30 patients. The objective response rate was 16.7% (95% CI: 3.5 approximately 30.3), with a stable disease in 56.7% (95% CI: 40.0 approximately 74.4) and a progressive disease in 26.7% (95% CI: 10.9 approximately 42.5) of patients, with a median follow up duration of 20 months for all the patients, The median duration of response, time to progression and overall survival were 2.1 months (95% CI: 0.4 approximately 3.9), 4.2 months (95% CI: 2.3 approximately 6.1) and 6.8 months (95% CI: 1.3 approximately 12.3), respectively, with a 1-year survival rate of 32%. The toxicity was evaluated in 30 patients, with neutropenia being most common. Renal impairment was seen in two patients with grade 3 creatinine elevation and liver enzyme elevation in four with grades 3 and 4. CONCLUSION Although DP was an active combination regimen, with a tumor control rate of about 73% and with moderate tolerance, adjustment of the administration schedule, with further evaluation of other combination chemotherapies of docetaxel with new agents, other than cisplatin, seem warranted.

Hepatocyte Growth Factor Promotes Cell Survival by Phosphorylation of BAD in Gastric Cancer Cells

Hepatocyte growth factor (HGF) is one of the survival factors with a potent ability to promote cell survival by inhibiting apoptosis. However, the mechanism by which HGF inhibits apoptosis is not completely understood. To explore the genes associated with stomach cancer cell survival by HGF, we used cDNA microarray technology and selected 26 genes up- or downregulated in NUGC-3 cells during HGF treatment. Among them, BAD was confirmed to be upregulated at the RNA and protein levels by HGF treatment. We investigated the effect of BAD induced by HGF on cell survival. HGF treatment inhibited apoptosis induced by BAD overexpression and enhanced BAD phosphorylation. Pretreatment of NUGC-3 cells with PI3K inhibitors, LY 294002, decreased HGF-induced BAD phosphorylation on Ser136 whereas an MEK inhibitor, PD 98059, decreased BAD phosphorylation on Ser112. In conclusion, increases in BAD levels as well as BAD phosphoryation by HGF might contribute to HGF-mediated cell survival in NUGC-3 cells.

Gastric Pseudotumoral Lesion Caused by a Fish Bone Mimicking a Gastric Submucosal Tumor

Gastric complications following unintentional foreign body ingestion are extremely rare. Here, we report the case of a 59-year-old healthy woman who presented with nonspecific abdominal pain and an apparent gastric submucosal tumor that was incidentally detected by gastrofiberscopy. The patient underwent laparoscopic surgery, which revealed an intact gastric wall with no tumor invasion, deformity, or evidence of a gastric submucosal lesion. However, an impacted fish bone was found.

Clinical Outcomes according to Primary Treatment in Gastric Cancer Patients with Peritoneal Seeding

Purpose Peritoneal seeding of gastric cancer is known to have a poor prognosis. With the diagnosis of peritoneal seeding, there is no effective treatment modality. Gastrectomy with chemotherapy or primary chemotherapy is basically one of major options for this condition. This study was conducted to compare the clinical outcomes of these treatments and to identify the better way to improve the prognosis of patients with peritoneal seeding. Materials and Methods Between 2001 and 2007, gastric cancer patients with peritoneal seeding by preoperative or intraoperative diagnosis were reviewed retrospectively. The enrolled patients were divided as primary gastrectomy and primary chemotherapy group. Clinicopathologic characteristics and clinical outcomes of groups were analyzed and compared. Results Fifty-four patients were enrolled. 21 patients belonged to the group of primary gastrectomy and 33 patients were to the primary chemotherapy group. Among 33 patients of the primary chemotherapy group, 17 patients were received only chemotherapy and 16 patients were received gastrectomy due to the good responses of primary chemotherapy. The 3 years survival rates were 14% in primary gastrectomy group, 55% in patients who received gastrectomy after primary chemotherapy, and 0% in patients with primary chemotherapy only. Conclusions Although this study had many limitations, some valuable information was produced. In terms of survival benefits for the gastric cancer patients with peritoneal seeding, primary gastrectomy and additional gastrectomy after primary chemotherapy revealed the better clinical outcomes. But, prospective randomized clinical study and multi-center study are should be performed to decide proper treatment for gastric cancer patients with peritoneal seeding.

Down-regulation of survivin suppresses uro-plasminogen activator through transcription factor JunB

Survivin, a member of the inhibitors of apoptosis protein family, is expressed during development and in various human cancers. However, the clinical relevance of survivin in cancer is still a matter of debate. Genes induced by hepatocyte growth factor (HGF) were screened using cDNA microarray technology in the stomach cancer cell lines, NUGC3 and MKN28. The levels of JunB, survivin, and uro-plasminogen activator (uPA) were up-regulated in cells treated with HGF in a dose-dependent manner. HGF-induced up regulation of JunB, survivin, and uPA was inhibited by pre-treatment with a MEK inhibitor (PD 98059). HGF-induced up-regulation of uPA was repressed by survivin knockdown. HGF enhanced the binding activity of JunB to the survivin promoter in control cells, but not in the JunB-shRNA cells. Transfection with survivin-shRNA resulted in a decrement of cell proliferation, as determined with MTT assays. In an in vitro invasion assay, significantly fewer cells transfected with survivin shRNA than control cells were able to invade across a Matrigel membrane barrier. In conclusion, survivin appeared to play an important role in the up-regulation of uPA induced by HGF via JunB and might contribute to HGF-mediated tumor invasion and metastasis, which may serve as a promising target for gastric cancer therapy.