4-(5-benzo(1-3)dioxol-5-yl-4-pyridin-2-yl-1h-imidazol-2-yl)benzamide and Stomach-Neoplasms

Peritoneal dissemination is the most frequent metastatic pattern of advanced gastric cancer and the main cause of death in gastric cancer patients. Transforming growth factor-beta1 (TGF- ß1), one of the most potent fibrotic stimuli for human peritoneal mesothelial cells, has been shown to play an important role in this process. In this study, we investigated the effect of TGF- ß1 signaling blockade in gastric cancer cell (GCC)-induced human peritoneal mesothelial cell (HPMC) fibrosis. HPMCs were cocultured with the high TGF- ß1 expressing GCC line SGC-7901 and various TGF- ß1 signaling inhibitors or SGC-7901 transfected with TGF-ß1-specific siRNA. HPMC fibrosis was monitored on the basis of morphology. Expression of the epithelial cell marker, E-cadherin, and the mesenchymal marker, α-smooth muscle actin (α-SMA), was evaluated by Western blotting and immunofluorescence confocal imaging. GCC adhesion to HPMC was also assayed. In nude mouse tumor model, the peritoneal fibrotic status was monitored by immunofluorescent confocal imaging and Masson's trichrome staining; formation of metastatic nodular and ascites fluid was also evaluated. Our study demonstrated that GCC expressing high levels of TGF-ß1 induced HMPC fibrosis, which is characterized by both upregulation of E-cadherin and downregulation of α-SMA. Furthermore, HPMC monolayers fibrosis was reversed by TGF- ß1 signaling blockade. In vivo, the TGF- ß1 receptor inhibitor SB-431542 partially attenuated early-stage gastric cancer peritoneal dissemination (GCPD). In conclusion, our study confirms the significance of TGFß1 signaling blockade in attenuating GCPD and may provide a therapeutic target for clinical therapy.

Topics: Actins; Animals; Benzamides; Dioxoles; Epithelial Cells; Fibrosis; Humans; Male; Mice; Mice, Inbred BALB C; Neoplasm Invasiveness; Peritoneum; Signal Transduction; Stomach Neoplasms; Transforming Growth Factor beta1

Gastric cancer cells leaving the primary tumour are exposed to low oxygen levels in the peritoneal cavity; however, peritoneal metastatic phenotypes of hypoxic cancer cells remain unclear. We used 6 gastric cancer cell lines, including 3 diffuse-type gastric cancer (DGC) and 3 non-DGC cell lines. Using adhesion assay, we examined the effect of hypoxic conditions on their ability to adhere to peritoneal components. The expression level of transforming growth factor-beta (TGF-beta) and integrins mRNA of cancer cells was examined using reverse transcriptase-polymerase chain reaction. We further examined the effect of anti-integrin neutralising antibodies and a TGF-beta receptor inhibitor on the adhesion ability of hypoxic cancer cells. The binding ability of DGC cells was higher than that of non-DGC cells; it was significantly increased by hypoxic (1% O2) conditions compared to normoxic (21% O2) conditions. In contrast, no remarkable change in adhesion ability was observed in the non-DGC cells under normoxic and hypoxic conditions. Integrins and TGF-beta expression of hypoxic DGC cells was significantly higher than that of normoxic cells. TGF-beta increased the adhesion ability and alpha2-, alpha3- and alpha5-integrin expression of hypoxic DGC cells, whereas the TGF-beta receptor inhibitor decreased them. Neutralising antibodies against alpha2-, alpha3- and alpha5-integrin inhibited the adhesion ability of DGC cells. These findings suggested that hypoxic conditions promote the adhesion of DGC cells to the peritoneum. The upregulation of alpha2-, alpha3- and alpha5-integrin by TGF-beta under hypoxic conditions may be one of the mechanisms responsible for the high metastatic potential of hypoxic DGC cells to the peritoneum.

Topics: Antibodies, Neutralizing; Benzamides; Cell Adhesion; Cell Hypoxia; Cell Line, Tumor; Dioxoles; Humans; Integrins; Neoplasm Proteins; Peritoneal Neoplasms; Phosphorylation; Receptors, Transforming Growth Factor beta; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Smad2 Protein; Smad3 Protein; Stomach Neoplasms; Transforming Growth Factor beta

Human peritoneal mesothelial cells (HPMCs) in intact mesothelium have been demonstrated to protect against tumor peritoneal metastasis. We have previously reported that gastric cancer cells can induce peritoneal apoptosis, lead to damage of peritoneum integrity, and therefore promote peritoneal metastasis. In this study, we investigated the effects of TGF-beta1 on tumor-mesothelial interaction. Briefly, the levels of various soluble factors, in particular TGF-beta1, were measured. HMrSV5 cells, a human peritoneal mesothelial cell line, were co-incubated with TGF-beta1, gastric cancer cells, or gastric cancer cells and TGF-beta1 receptor inhibitor SB431542. The expressions of smad 2/3 and phosphorylated smad 2/3, indicator of TGF-beta/Smads pathway activation, were evaluated. Then the morphological changes of HPMCs were observed. The cell damage was quantitatively determined by fluorescent microscopy and flow cytometry. Tumor-mesothelial cell adhesion was also examined. Results showed a significant elevation of TGF-beta1 expression, which is companied by dramatically increased phosphorylated-smad 2/3 levels, after mesothelial cell co-culture with the gastric cancer cell line. In addition, mesothelial cells exposed to gastric cancer cells or TGF-beta1 became exfoliated and exhibited signs of injury, while blocking TGF-beta1 can partially inhibit these effects. These results indicate that soluble factors, such as TGF-beta1, produced in autocrine/paracrine manner in the peritoneal cavity, affect the morphology and function of mesothelial cells so that the resulting environment becomes favorable for peritoneal metastases.

Topics: Apoptosis; Autocrine Communication; Benzamides; Carcinoma; Cell Adhesion; Cell Shape; Cells, Cultured; Coculture Techniques; Culture Media, Conditioned; Culture Media, Serum-Free; Dioxoles; Epithelial Cells; Epithelium; Humans; Neoplasm Metastasis; Paracrine Communication; Peritoneal Neoplasms; Receptors, Transforming Growth Factor beta; Stomach Neoplasms; Transforming Growth Factor beta1