Daisuke Fujimoto

The activation of Proteinase-Activated Receptor-1 (PAR1) mediates gastric cancer cell proliferation and invasion

BackgroundIn addition to regulating platelet function, the G protein-coupled sub-family member Proteinase-activated receptor-1 (PAR1) has a proposed role in the development of various cancers, but its exact role and mechanism of action in the invasion, metastasis, and proliferation process in gastric cancer have yet to be completely elucidated. Here, we analyzed the relationship between PAR1 activation, proliferation, invasion, and the signaling pathways downstream of PAR1 activation in gastric cancer.MethodsWe established a PAR1 stably transfected MKN45 human gastric cancer cell line (MKN45/PAR1) and performed cell proliferation and invasion assays employing this cell line and MKN28 cell line exposed to PAR1 agonists (α-thrombin and TFLLR-NH2). We also quantified NF-κB activation by electrophoretic mobility shift assay (EMSA) and the level of Tenascin-C (TN-C) expression in conditioned medium by ELISA of MKN45/PAR1 following administration of α-thrombin. A high molecular weight concentrate was derived from the resultant conditioned medium and subsequent cultures of MKN45/PAR1 and MKN28 were exposed to the resultant concentrate either in the presence or absence of TN-C-neutralizing antibody. Lysates of these subsequent cells were probed to quantify levels of phospholyrated Epidermal Growth Factor Receptor (EGFR).ResultPAR1 in both PAR1/MKN45 and MKN28 was activated by PAR1 agonists, resulting in cell proliferation and matrigel invasion. We have shown that activation of NF-κB and EGFR phosphorylation initially were triggered by the activation of PAR1 with α-thrombin. Quantitative PCR and Western blot assay revealed up-regulation of mRNA and protein expression of NF-κB target genes, especially TN-C, a potential EGFR activator. The suppressed level of phosphorylated EGFR, observed in cells exposed to concentrate of conditioned medium in the presence of TN-C-neutralizing antibody, identifies TN-C as a putative autocrine stimulatory factor of EGFR possibly involved in the sustained PAR1 activation responses observed.ConclusionOur data indicate that in gastric carcinoma cells, PAR1 activation can trigger an array of responses that would promote tumor cell growth and invasion. Over expression of NF-κB, EGFR, and TN-C, are among the effects of PAR1 activation and TN-C induces EGFR activation in an autocrine manner. Thus, PAR1 is a potentially important therapeutic target for the treatment of gastric cancer.

PAR1 participates in the ability of multidrug resistance and tumorigenesis by controlling Hippo-YAP pathway

The Hippo pathway significantly correlates with organ size control and tumorigenesis. The activity of YAP/TAZ, a transducer of the Hippo pathway, is required to sustain self-renewal and tumor-initiation capacities in cancer stem cells (CSCs). But, upstream signals that control the mammalian Hippo pathway have not been well understood. Here, we reveal a connection between the Protease-activated receptor 1 (PAR1) signaling pathway and the Hippo-YAP pathway in gastric cancer stem-like cells. The selective PAR1 agonist TFLLR-NH2 induces an increase in the fraction of side population cells which is enriched in CSCs, and promotes tumorigenesis, multi cancer drug resistance, cell morphological change, and cell invasion which are characteristics of CSCs. In addition, PAR1 activation inhibits the Hippo-YAP pathway kinase Lats via Rho GTPase. Lats kinase inhibition in turn results in increased nuclear localization of dephosphorylated YAP. Furthermore, PAR1 activation confers CSCs related traits via the Hippo-YAP pathway, and the Hippo-YAP pathway correlates with epithelial mesenchymal transition which is induced by PAR1 activation. Our research suggests that the PAR1 signaling deeply participates in the ability of multi drug resistance and tumorigenesis through interactions with the Hippo-YAP pathway signaling in gastric cancer stem-like cells. We presume that inhibited YAP is a new therapeutic target in the treatment human gastric cancer invasion and metastasis by dysregulated PAR1 or its agonists. The Hippo pathway significantly correlates with organ size control and tumorigenesis. The activity of YAP/TAZ, a transducer of the Hippo pathway, is required to sustain self-renewal and tumor-initiation capacities in cancer stem cells (CSCs). But, upstream signals that control the mammalian Hippo pathway have not been well understood. Here, we reveal a connection between the Protease-activated receptor 1 (PAR1) signaling pathway and the Hippo-YAP pathway in gastric cancer stem-like cells. The selective PAR1 agonist TFLLR-NH2 induces an increase in the fraction of side population cells which is enriched in CSCs, and promotes tumorigenesis, multi cancer drug resistance, cell morphological change, and cell invasion which are characteristics of CSCs. In addition, PAR1 activation inhibits the Hippo-YAP pathway kinase Lats via Rho GTPase. Lats kinase inhibition in turn results in increased nuclear localization of Dephosphorylated YAP. Furthermore, PAR1 activation confers CSCs related traits via the Hippo-YAP pathway, and the Hippo-YAP pathway correlates with epithelial mesenchymal transition which is induced by PAR1 activation. Our research suggests that the PAR1 signaling deeply participates in the ability of multi drug resistance and tumorigenesis through interactions with the Hippo-YAP pathway signaling in gastric cancer stem-like cells. We presume that inhibited YAP is a new therapeutic target in the treatment human gastric cancer invasion and metastasis by dysregulated PAR1 or its agonists.

The activation of proteinase-activated receptor-1 (PAR1) promotes gastric cancer cell alteration of cellular morphology related to cell motility and invasion

Cell motility proceeds by cycles of edge protrusion, adhesion and retraction. Whether these functions are coordinated by biochemical or biomechanical processes is unknown. Tumor invasion and metastasis is directly related to cell motility. We showed that stimulation of proteinase-activated receptor-1 (PAR1) can trigger an array of responses that would promote tumor cell growth and invasion. Thus, we examined aspects of PAR1 activation related to cell morphological change that might contribute to cell motility. We established a PAR1 stably transfected MKN45 gastric cancer cell line (MKN45/PAR1). We examined morphological changes, Rho family activation and overexpression of cytoskeletal protein in cells exposed to PAR1 agonists (α-thrombin and TFLLR-NH2). MKN45/PAR1 grows with an elongated and polarized morphology, extending pseudopodia at the leading edge. However, in the presence of PAR1 antagonist, MKN45/PAR1 did not show any changes in cell shape upon addition of either α-thrombin or TFLLR-NH2. Activated PAR1 induced RhoA and Rac1 phosphorylation, and subsequent overexpression of myosin IIA and filamin B which are stress fiber components that were identified by PMF analysis of peptide mass data obtained by MALDI-TOF/MS measurement. Upon stimulation of MKN45/PAR1 for 24 h with either α-thrombin or TFLLR-NH2, the distribution of both myosin IIA and filamin B proteins shifted to being distributed throughout the cytoplasm to the membrane, with more intense luminescence signals than in the absence of stimulation. These results demonstrate that PAR1 activation induces cell morphological change associated with cell motility via Rho family activation and cytoskeletal protein overexpression, and has a critical role in gastric cancer cell invasion and metastasis.

Thrombin conducts epithelial‑mesenchymal transition via protease‑activated receptor‑1 in human gastric cancer

Epithelial-mesenchymal transition (EMT) is thought to be a key step for cancer metastasis. Using an immunohistochemical approach with gastric carcinoma tissue, we found the expression of protease-activated receptor-1 (PAR1), along with a metalloproteinase known to activate PAR1, were associated with poorer prognosis, compared with expression-negative tumors, and activated PAR1 promotes gastric cancer cell invasion and proliferation in vivo. In this study we observed EMT induction by the PAR1 agonist α-thrombin, in human gastric cell lines stably expressing PAR1. We investigated α-thrombin-induced changes in the cell forms of pcDNA3.1-MKN45 (MKN45/Mock), pcDNA3.1‑PAR1 transfected MKN45 (MKN45/PAR1), and MKN74. Expression levels of epithelial and mesenchymal markers as well as the distribution of transcriptional factors of E-cadherin in the cytoplasm and nucleus were also noted in these cell lines. We observed α-thrombin-induced morphological changes in MKN45/PAR1 and MKN74 cells. Western blotting and immunohistochemistry of these cells indicated a fall in the expression level of E-cadherin and an increase in fibronectin expression after 48 h. PAR1 activation also induced significant increases in nuclear levels of the Snail which is a repressor of E-cadherin gene expression. We found EMT in gastric cancer cell lines that underwent α-thrombin-induced PAR1 activation.

Five-Year Survival of Alpha-Fetoprotein-Producing Gastric Cancer with Synchronous Liver Metastasis: A Case Report

Alpha-fetoprotein-Producing gastric cancer is associated with poor prognosis because of frequent liver and lymph node metastasis. We present a case with synchronous liver metastasis who survived for 5 years. A 69-year-old man with upper abdominal pain was referred to our hospital. Gastrointestinal endoscopy revealed a Borrmann II-like tumor in the lower part of the stomach. Computed tomography revealed a tumor in the left lobe of the liver. Serum alpha-fetoprotein levels were markedly increased. We performed distal gastrectomy after administering oral tegafur/gimeracil/oteracil potassium and administered hepatic intra-arterial cisplatin injection. Liver metastasis showed partial response on computed tomography. Despite left hepatic lobectomy, further metastases to the liver and mediastinal lymph nodes became difficult to control. After sorafenib tosylate administration, stabilization of the disease was observed for 4 months. We conclude that hepatic intra-arterial chemotherapy and oral administration of sorafenib tosylate may potentially improve the prognosis in such cases.

Randomized Phase II trial of paclitaxel plus valproic acid vs paclitaxel alone as second-line therapy for patients with advanced gastric cancer.

The standard regimen of second-line chemotherapy for patients with unresectable gastric cancer has not been established. However, weekly paclitaxel (wPTX) has become the preferable second-line chemotherapy in Japan. Histone deacetylase (HDAC) inhibitors have been shown to have antiproliferative activity through cell-cycle arrest, differentiation, and apoptosis in gastric cancer cells. One HDAC inhibitor, valproic acid (VPA), also inhibits tumor growth by inducing apoptosis, and enhances the efficacy of paclitaxel in a mouse xenograft model of gastric cancer. wPTX plus VPA as a second-line chemotherapy is expected to improve survival in gastric cancer patients. A multicenter randomized Phase II study was conducted to compare the effects of wPTX plus VPA and wPTX alone. A total of 66 patients participated in this study. The primary end point of the study was overall survival, and secondary end points were progression-free survival, response rate, and assessment of peripheral neuropathy.

Retrocolic Roux-en-Y anastomosis for total laparoscopic distal gastrectomy: Fix-the-remnant-first technique

Herein we report our retrocolic Roux‐en‐Y anastomosis for laparoscopic distal gastrectomy and its feasibility.

RPN2 is effective biomarker to predict the outcome of combined chemotherapy docetaxel and cisplatin for advanced gastric cancer

Preoperative chemotherapy, often using docetaxel and cisplatin, is a famous treatment option for advanced gastric cancer in Japan. But, there are no effective biomarkers that predict the therapeutic outcome on gastric cancer. Ribophorin II (RPN2) silencing, which decreases glycosylation of P-glycoprotein (P-gp) and membrane localization, restores the sensitivity to docetaxel and cisplatin. We inquired whether RPN2 expression in advanced gastric cancer biopsy tissues may be a predictive biomarker for docetaxel and cisplatin combination preoperative chemotherapy. We judged RPN2 expression immunohistochemically in upper endoscopic biopsy tissues from 40 advanced gastric cancer patients, who received the combination preoperative chemotherapy of docetaxel and cisplatin and gastrectomy with D2 resection during 2008-2014, and compared clinicopathological effects between RPN2-positive and RPN2-negative groups. We also examined sensitivity of RPN2-knockout gastric cancer cells by genome editing to docetaxel and cisplatin. RPN2 expression was observed in 19 of 40 gastric cancer cases. The RPN2-negative group had better clinicopathological responses to docetaxel and cisplatin combination chemotherapy than the RPN2-positive group, especially, in assessment of the histopathological criteria to preoperative chemotherapy. And RPN2-negative group had a significantly higher overall survival and progression-free survival compared to the RPN2-positive group. We also found RPN2-knockout to change docetaxel and cisplatin sensitivity in vitro. RPN2 expression in upper endoscopic biopsy tissues can be an effective predictive biomarker for the treatment outcome to docetaxel and cisplatin combination preoperative chemotherapy in advanced gastric cancer.

Initial results of reduced port laparoscopic gastrectomy for gastric cancer

Reduced port laparoscopic gastrectomy (RPLG) for gastric cancer is started from some skilled surgeons in the selected cases. The procedures of RLPG have two ways that of using multi-channel-ports device and of using needle devices, reported from the meeting of 3 rd Reduced Port Surgery Forum 2014 or recent publications. The current results of RLPG were not inferior to the conventional laparoscopic gastrectomy (LG). But further improvements in the instruments, the technique, and the education would be required for the wider indication to the reduced port surgery.

A study of cell-free and concentrated ascites reinfusion therapy (CART) for intractable ascites associated with cancerous ascites.

205 Background: Intractable ascites associated with cancerous ascites causes severe abdominal distention, loss of appetite, poor nutritional condition and reduce the quality of life. We treat patients suffering from cancerous ascites by Cell-free and Concentrated Ascites Reinfusion Therapy (CART). But, cancerous ascites contains a lot of cellular components, and it easily cause filter obstruction. So we applied new method of CART: KM-CART in cancerous ascites patients. This CART system has a filter cleaning function, so the system has less incidence of filter obstruction. We report on our experience on CART for patients with cancerous ascites. Methods: Since November 2009 to August 2014, we applied CART in 31 cases of cancerous ascites (gastric cancer, 13; colorectal cancer, 6; pancreatic cancer, 10; others, 2). Results: On average, 3.8kg (range 1.2-7.5kg) of ascites were filtrated and concentrated to 440g (70-1110g). In all cases abdominal distention disappeared and abdominal girth decreased. Side effect...