Trophoblast cell surface antigen-2 phosphorylation triggered by binding of galectin-3 drives metastasis through down-regulation of E-cadherin.

The expression of trophoblast cell surface antigen-2 (Trop-2) is enhanced in many tumor tissues and is correlated with increased malignancy and poor survival of patients with cancer. Previously, we demonstrated that the Ser-322 residue of Trop-2 is phosphorylated by protein kinase Cα (PKCα) and PKCδ. Here, we demonstrate that phosphomimetic Trop-2 expressing cells have markedly decreased E-cadherin mRNA and protein levels. Consistently, mRNA and protein of the E-cadherin-repressing transcription factors zinc finger E-Box binding homeobox 1 (ZEB1) were elevated, suggesting transcriptional regulation of E-cadherin expression. The binding of galectin-3 to Trop-2 enhanced the phosphorylation and subsequent cleavage of Trop-2, followed by intracellular signaling by the resultant C-terminal fragment. Binding of ß-catenin/transcription factor 4 (TCF4) along with the C-terminal fragment of Trop-2 to the ZEB1 promoter upregulated ZEB1 expression. Of note, siRNA-mediated knockdown of ß-catenin and TCF4 increased the expression of E-cadherin through ZEB1 downregulation. Knockdown of Trop-2 in MCF-7 cells and DU145 cells resulted in downregulation of ZEB1 and subsequent upregulation of E-cadherin. Furthermore, wild-type and phosphomimetic Trop-2 but not phosphorylation-blocked Trop-2 were detected in the liver and/or lung of some nude mice bearing primary tumors inoculated intraperitoneally or subcutaneously with wild-type or mutated Trop-2 expressing cells, suggesting that Trop-2 phosphorylation, plays an important role in tumor cell mobility in vivo, too. Together with our previous finding of Trop-2 dependent regulation of claudin-7, we suggest that the Trop-2-mediated cascade involves concurrent derangement of both tight and adherence junctions, which may drive metastasis of epithelial tumor cells.

Impact of Tumor Subclassifications for Identifying an Appropriate Surgical Strategy in Patients with Intrahepatic Cholangiocarcinoma.

BACKGROUND: Intrahepatic cholangiocarcinoma (ICC) is subclassified into small and large duct types. The impact of these subclassifications for identifying appropriate surgical strategies remains unclear. PATIENTS AND METHODS: This study included 118 patients with ICC who underwent liver resection. Based on the pathological examination results, the participants were divided into the small duct-type ICC group (n = 64) and large duct-type ICC group (n = 54). The clinicopathological features and postoperative outcomes were compared between the two groups to investigate the impact of subclassification for selecting appropriate surgical strategies. RESULTS: Ten patients in the small duct-type ICC group had synchronous or metachronous hepatocellular carcinoma. The large duct-type ICC group had higher proportions of patients who underwent major hepatectomy, extrahepatic bile duct resection, portal vein resection, and lymph node sampling or dissection than the small duct-type ICC group. The large duct-type ICC group had significantly higher incidences of lymph node metastasis/recurrence and pathological major vessel invasion than the other. The small duct-type ICC group exhibited significantly higher recurrence-free and overall survival rates than the large duct-type ICC group. Further, the large duct-type ICC group had a significantly higher incidence of lymph node metastasis/recurrence than the small duct-type ICC at the perihilar region group. CONCLUSIONS: Suitable surgical strategies may differ between the small and large duct-type ICCs. In patients with large duct-type ICCs, hepatectomy with lymph node dissection and/or biliary reconstruction should be considered, whereas hepatectomy without these advanced procedures can be suggested for patients with small duct-type ICCs.

[Surgical Technique for Mesorectal Division in the Robotic Anterior Resection for Rectal Cancer].

Since April 2018, robot-assisted rectal resection has been approved as an insurance medical treatment, and robot- assisted rectal resection is rapidly becoming widespread. Even in robot-assisted laparoscopic surgery, mesorectal division is difficult in a narrow pelvic cavity. At the beginning of the operation, Vessel Sealer ExtendTM(price 89,250 yen)was used, but as the procedure became stable, the mesorectal division was started with bipolar forceps and monopolar scissors. The purpose of this study was to investigate the mesorectal division time and postoperative complications associated with changes in the procedure. 36 patients who underwent robot-assisted anterior resection for rectal cancer by the same surgeon from January 2019 to December 2021. We compared mesorectal division time and postoperative complication. Median operation time were 267 minutes, median console time were 132 minutes. There were no complications such as intestinal obstruction or anastomotic leakage. There was no difference in mesorectal division time time between Vessel Sealer groups and Scissors groups(14 min 55 sec vs 16 min 5 sec). The mesorectal division with bipolar forceps and monopolar scissors could be performed without extending the operation time, and could be performed with cost-benefit and safely.

Lipocalin-2 negatively regulates epithelial-mesenchymal transition through matrix metalloprotease-2 downregulation in gastric cancer.

BACKGROUND: Although the role of Lipocalin-2 (LCN2) in cancer development has been focused on recent studies, the molecular mechanisms and clinical relevance of LCN2 in gastric cancer (GC) still remain unclear. METHODS: Transcriptome analysis of GC samples from public human data was performed according to Lauren's classification and molecular classification. In vitro, Western blotting, RT-PCR, wound healing assay and invasion assay were performed to reveal the function and mechanisms of LCN2 in cell proliferation, migration and invasion using LCN2 knockdown cells. Gene set enrichment analysis (GSEA) of GC samples from public human data was analyzed according to LCN2 expression. The clinical significance of LCN2 expression was investigated in GC patients from public data and our hospital. RESULTS: LCN2 was downregulated in diffuse-type GC, as well as in Epithelial-Mesenchymal Transition (EMT) type GC. LCN2 downregulation significantly promoted proliferation, invasion and migration of GC cells. The molecular mechanisms of LCN2 downregulation contribute to Matrix Metalloproteinases-2 (MMP2) stimulation which enhances EMT signaling in GC cells. GSEA revealed that LCN2 downregulation in human samples was involved in EMT signaling. Low LCN2 protein and mRNA levels were significantly associated with poor prognosis in patients with GC. LCN2 mRNA level was an independent prognostic factor for overall survival in GC patients. CONCLUSIONS: LCN2 has a critical role in EMT signaling via MMP2 activity during GC progression. Thus, LCN2 might be a promising therapeutic target to revert EMT signaling in GC patients with poor outcomes.

[Impact of Sarcopenia on Patients with Advanced Gastric Cancer Who Underwent Surgery].

This study aimed to investigate the short- and long-term outcomes in patients with sarcopenia who underwent surgery for advanced gastric cancer. We included 76 patients with pStage Ⅱ or Ⅲ gastric cancer who underwent gastrectomy between January 2017 and June 2021. Patients with pT3N0 cancer were excluded. Using the Asian Working Group for Sarcopenia( AWGS)2019 criteria, the patients were divided into the sarcopenia group(S group)and the non-sarcopenia group (NS group). The surgical outcomes, effects on postoperative adjuvant chemotherapy, and prognosis of the 2 groups were evaluated and compared. No significant differences were observed in the operative time, blood loss, postoperative hospital stays, or incidence of postoperative complications with a grade higher than Clavien-Dindo Grade Ⅱ. The number of patients who received postoperative adjuvant chemotherapy was 5(26.3%)in the S group and 38(66.7%)in the NS group which was significantly lower in the S group(p=0.003). The 3-year overall survival rate was 45.7% in the S group and 71.0% in the NS group(p=0.302). There was no significant difference but survival rate was lower in the S group. The results suggest that postoperative adjuvant chemotherapy is not always available for patients with advanced gastric cancer, and that may worsen the prognosis.

[A Case of Robotic Surgery for Local and Peritoneal Recurrence of Colorectal Cancer].

A 35-year-old women with sigmoid cancer(pT4aN1aM0, pStage Ⅲb)underwent laparoscopic sigmoidectomy. She had 8 courses of CapeOX for adjuvant chemotherapy, but follow up CT scan 1 year after the operation detected intraabdominal nodules in anastomotic site and in left lower quadrant of abdomen. After 10 courses of IRIS plus bevacizumab, the both intraabdominal nodules decreased in size. Robot assisted laparoscopic lower anterior resection and laparoscopic disseminated nodule resection were performed. The patient had no postoperative complications and the postoperative course was good. She remains alive without recurrence at 6 months after the second operation.

Asporin Expression on Stromal Cells and/or Cancer Cells Might Be A Useful Prognostic Marker in Patients with Diffuse-Type Gastric Cancer.

BACKGROUND: Asporin (ASPN), a member of the proteoglycan family, has been shown to have a close correlation with cancer progression. It is not known whether ASPN is an oncogenic driver or a tumor suppressor in human gastric cancer. We sought herein to determine the relationship between ASPN expression and clinicopathological features of gastric cancer. PATIENTS AND METHODS: A total of 296 gastric cancer patients (diffuse type, n = 144; intestinal type, n = 152) were enrolled. The ASPN expression level in each case was analyzed by immunohistochemistry. RESULTS: ASPN was mainly found on stromal cells, especially on fibroblasts in tumor stroma, i.e., cancer-associated fibroblasts. The ASPN expression on either cancer cells or stromal cells was significantly high in macroscopic scirrhous-type tumors (p < 0.001) and histologically abundant stroma-type tumors (p < 0.001). Interestingly, a Kaplan-Meier survival curve of the 144 cases of diffuse-type gastric cancer revealed a significantly poorer prognosis in patients with ASPN-positive expression (p = 0.043; log rank) compared to those with ASPN-negative expression, but the prognoses were not significantly different in these subgroups of the 152 cases of intestinal-type gastric cancer. A multivariate analysis with respect to overall survival showed that ASPN expression on stromal cells and/or cancer cells was significantly correlated with overall survival in patients with diffuse-type gastric cancer (p = 0.041). CONCLUSION: In gastric cancer, ASPN was expressed mainly on stromal cells and partially on cancer cells. ASPN expression on stromal cells and/or cancer cells might be a useful prognostic marker in patients with diffuse-type gastric cancer.

Serine threonine kinase 11/liver kinase B1 mutation in sporadic scirrhous-type gastric cancer cells.

Scirrhous-type gastric carcinoma (SGC), which is characterized by the rapid proliferation of cancer cells accompanied by extensive fibrosis, shows extremely poor survival. A reason for the poor prognosis of SGC is that the driver gene responsible for SGC has not been identified. To identify the characteristic driver gene of SGC, we examined the genomic landscape of six human SGC cell lines of OCUM-1, OCUM-2M, OCUM-8, OCUM-9, OCUM-12 and OCUM-14, using multiplex gene panel testing by next-generation sequencing. In this study, the non-synonymous mutations of serine threonine kinase 11/liver kinase B1 (STK11/LKB1) gene were detected in OCUM-12, OCUM-2M and OCUM-14 among the six SGC cell lines. Capillary sequencing analysis confirmed the non-sense or missense mutation of STK11/LKB1 in the three cell lines. Western blot analysis showed that LKB1 expression was decreased in OCUM-12 cells and OCUM-14 cells harboring STK11/LKB1 mutation. The mammalian target of rapamycin (mTOR) inhibitor significantly inhibited the proliferation of OCUM-12 and OCUM-14 cells. The correlations between STK11/LKB1 expression and clinicopathologic features of gastric cancer were examined using 708 primary gastric carcinomas by immunochemical study. The low STK11/LKB1 expression group was significantly associated with SGC, high invasion depth and frequent nodal involvement, in compared with the high STK11/LKB1 expression group. Collectively, our study demonstrated that STK11/LKB1 mutation might be responsible for the progression of SGC, and suggested that mTOR signaling by STK11/LKB1 mutation might be one of therapeutic targets for patients with SGC.

Circulating tumor cells with FGFR2 expression might be useful to identify patients with existing FGFR2-overexpressing tumor.

Fibroblast growth factor receptor (FGFR) is associated with proliferation, migration, and angiogenesis of carcinomas, and FGFR signaling inhibitors are considered a key drug for the treatment of solid tumors with FGFR overexpression. Amplification of FGFR2 is reportedly identified in 3%-10% of gastric cancers (GCs). The aim of this study is to clarify whether the identification of the circulating tumor cells (CTCs) with FGFR2 overexpression is useful to detect patients with FGFR2-overexpressing GC. One hundred GC patients who underwent gastrectomy were enrolled. A total volume of 8 mL of peripheral blood was collected from each patient just before gastrectomy, and mononuclear cells were enriched by Ficol density gradient centrifugation. These cells were immunostained with PI/CD45/EpCAM/FGFR2. The number of CTCs with FGFR2 expression in each sample was enumerated by FACScan. The FGFR2 expression level of the resected primary tumor was assessed by immunohistochemistry. The number of FGFR2-positive CTCs in the GC patients' peripheral blood was significantly correlated with the FGFR2 expression level of the primary GC. The relapse-free survival of the patients with FGFR2-positive CTCs (≥5 cells/10 mL blood) was significantly poorer (P = .018, log-rank) than that of the patients without FGFR2-positive CTCs (<5 cell/10 mL blood). These findings suggested that the determination of FGFR2-positive CTCs might help identify an existing tumor with FGFR2 overexpression.

[Pancreatic Cancer with Hemobilia after Biliary Self-Expandable Metallic Stent Placement during Neoadjuvant Chemotherapy-A Case Report].

A 67-year-old woman was diagnosed with borderline resectable pancreatic cancer and obstructive jaundice. A covered self-expandable metallic stent(SEMS)was placed endoscopically. Neoadjuvant chemotherapy with gemcitabine plus nabpaclitaxel was provided. Forty-seven days after the SEMS placement, she presented with hematemesis. Computed tomography revealed migration of SEMS into the small bowel. No pseudoaneurysms were detected. Upper digestive endoscopy demonstrated hemobilia without obvious causes of bleeding in the stomach or duodenum. As hemorrhage recurrence was confirmed in the bile duct, we performed pancreaticoduodenectomy. Thus, bile duct hemorrhage can occur in patients with pancreatic cancer after SEMS placement.

[A Case of Metachronous Liver Metastasis of Gallbladder Cancer Controlled by Liver Resection].

The patient was an 81-year-old woman. She had undergone extended cholecystectomy with lymph node dissection for primary gallbladder cancer. The pathological diagnosis was moderately differentiated tubular adenocarcinoma(pT2, N0, M0, pStage Ⅱ). Eleven months after the initial surgery, dynamic CT revealed a solitary low-enhanced tumor in S5 ofthe liver. As the tumor was detected with abnormal FDG uptake by PET-CT, we diagnosed the patient with a metastatic liver tumor from gallbladder cancer. Although chemotherapy was considered, conservative treatment was selected as the patient did not want to undergo chemotherapy. Therefore, laparoscopic partial liver resection was performed 15 months after the initial surgery with the consideration that no other distant metastasis was found, and tumor markers were within normal ranges. The postoperative course was uneventful, and the patient was discharged 13 days after liver resection without any morbidities. The resected tumor was pathologically diagnosed as a metastatic liver tumor from gallbladder cancer. She has achieved 18 months recurrence free survival after the liver resection without adjuvant chemotherapy. Although liver resection for a metastatic liver tumor from gallbladder cancer is not a standardized treatment, it may be a therapeutic option in cases of limited metastasis.

[Undifferentiated Carcinoma of the Gallbladder with Rapid Postoperative Progression-A Case Report].

A 74-year-old woman presented with epigastric pain. Imaging revealed a tumor measuring 80 mm, with internal necrosis, originating from the gallbladder and invading the liver. We performed extended anterior segmentectomy of the liver and lymph node resection following a preoperative diagnosis of gallbladder cancer. Histologically, the tumor was diagnosed as an undifferentiated carcinoma of the gallbladder. Although curative resection was performed, the patient developed recurrence with liver metastasis and peritoneal dissemination after 6 postoperative weeks and died after 10 postoperative weeks.

Comparison of Short-Term Surgical Outcomes of Two Types of Robotic Gastrectomy for Gastric Cancer: Ultrasonic Shears Method Versus the Maryland Bipolar Forceps Method.

BACKGROUND: This study investigated the impact and short-term surgical outcomes of two different main energy devices for robotic gastrectomy for gastric cancer. The outcomes of robotic gastrectomy with ultrasonic shears and those of robotic gastrectomy with conventional forceps were compared. METHODS: We retrospectively evaluated 171 patients who underwent robotic distal gastrectomy or total gastrectomy for gastric cancer. We classified patients into the ultrasonic shears (US) and Maryland bipolar (MB) forceps groups according to the main energy device used for robotic gastrectomy. RESULTS: We extracted 58 patients from the US group and 58 patients from the MB forceps groups using propensity score matching. The total console time (310 min [interquartile range (IQR), 253-369 min] and 332 min, [IQR, 294-429 min]; p = 0.022) and the console time to gastrectomy (222 min [IQR, 177-266 min] and 247 min [IQR, 208-321 min]; p = 0.004) were significantly shorter in the US group than in the MB forceps group. Less blood loss occurred in the US group than in the MB forceps group (20 mL [IQR, 10-40 mL] and 30 mL [IQR, 16-80 mL]; p = 0.014). The postoperative complication rate and postoperative hospital stay length were similar between groups. A multivariate multiple linear regression analysis demonstrated that the use of an ultrasonically activated device was one an independent factor that reduced the operative time of robotic gastrectomy. CONCLUSION: Using ultrasonic shears as the main energy device may contribute to better surgical outcomes after robotic gastrectomy for gastric cancer.

Application of Indocyanine Green Fluorescence Imaging for Tumor Localization during Robot-Assisted Hepatectomy.

The efficacy of indocyanine green (ICG) fluorescence imaging for visualizing hepatic tumors in robot-assisted hepatectomy (RAH) should be validated. This study included 30 consecutive patients with 33 collective tumors who underwent RAH. ICG was administered at a dose of 0.5 mg/kg before surgery. ICG fluorescence imaging was performed intraoperatively. In total, 28 patients with a combined total of 31 tumors underwent ICG fluorescence imaging. Further, 26 (84%) tumors were identified on hepatic surfaces prior to hepatic transection. The fluorescence signals of eight tumors were detected on hepatic raw surfaces during parenchymal dissection, thereby enabling surgeons to adjust the transection planes to ensure appropriate surgical margins. One patient with intrahepatic cholangiocarcinoma tested positive for cancer cells at the dissected stump of the bile duct. However, in all patients in whom ICG fluorescence imaging was used, negative surgical margins were achieved at the site of the dissected hepatic parenchyma. On the other hand, one of two patients with ICG contraindications had a positive surgical margin surrounding the dissected hepatic parenchyma. The median operative time and volume of blood loss were 259 (range: 124-594) min and 150 (range: 1-1150) mL, respectively. ICG fluorescence imaging facilitates the easy identification of hepatic tumors, even in RAH. Hence, it can be useful for confirming appropriate surgical margins.

Establishment of a gastric cancer cell line with high microsatellite instability, OCUM-13, derived from Borrmann type-2 primary tumor.

Gastric cancer (GC) with microsatellite instability (MSI) has been reported to be sensitive to immunotherapy, however some of GC cases with MSI remain resistant to immunotherapy. Cancer cell lines showing MSI might be useful for the analysis of mechanisms of immunotherapy, while only a few GC cell lines with MSI are available so far. In this study, we established a unique GC cell line with MSI, OCUM-13, from a primary GC with abundant tumor-infiltrating lymphocytes. MSI assay indicated that OCUM-13 cells as well as the primary tumor showed a band shift in more than 3 of 5 microsatellite loci, suggesting that OCUM-13 did have high MSI. The subcutaneous inoculation of OCUM-13 cells into mice performed tumor formation. Insulin-like growth factor 1 receptor inhibitor decreased the growth of OCUM-13 cells. The newly established cell line with MSI, OCUM-13, might be useful for the analysis of cancer therapy for GC with MSI.

Dipeptidyl Peptidase-4 from Cancer-associated Fibroblasts Stimulates the Proliferation of Scirrhous-type Gastric Cancer Cells.

BACKGROUND/AIM: Cancer-associated fibroblasts (CAFs) may promote the malignancy of human scirrhous gastric cancer (SGC) cells. We conducted the present study to identify novel growth factors from CAFs. MATERIALS AND METHODS: OCUM-12 and 2 CAF cell lines were used. The proliferation of cancer cells was determined by the number of cancer cells or the MTT assay. The growth factor(s) were purified and characterized by the gel filtration chromatography and protein array. RESULTS: The molecular weight of the growth-stimulating factor was estimated to be approximately 66-669 kDa. Protein array of conditioned medium (CM) from CAFs indicated that dipeptidyl peptidase-4 (DPP-4) was one of the growth factors. The addition of CM increased the phosphorylation of C-X-C chemokine receptor 4 (CXCR4). The DPP-4 inhibitor significantly inhibited the growth-stimulating activity of CM. CONCLUSION: DPP-4 from CAFs might be one of the growth-stimulating factors for SGC through CXCR4.

Jejunal Mesentery Preservation Reduces Leakage at Esophagojejunostomy After Minimally Invasive Total Gastrectomy for Gastric Cancer: a Propensity Score-Matched Cohort Study.

PURPOSE: The mesentery of the jejunum (MJ) of the Roux limb is conventionally divided when Roux-en-Y reconstruction is performed after total gastrectomy for gastric cancer (GC). However, the impact of dividing or preserving the MJ on anastomotic leakage (AL) at the esophagojejunostomy (EJS) site after minimally invasive total gastrectomy for GC is unclear. METHODS: This retrospective cohort study enrolled 226 patients with GC who underwent EJS after laparoscopic or robotic total gastrectomy, including preservation of the MJ (n = 87) and division of the MJ (n = 137). The prevalence of anastomotic complications at the EJS and short-term outcomes were compared between groups using propensity score (PS) matching. RESULTS: After PS matching, 69 patients were selected for the preserving and dividing MJ groups. There were no significant intergroup differences in patient backgrounds, including oncological stage, body mass index, and gender ratio. After PS matching, overall and severe complications after surgery were compared between the preserving and dividing MJ groups (21.7% vs. 27.5%, p = 0.554 and 8.7% vs. 13.8%, p = 0.137, respectively). However, the rate of AL at the EJS was significantly lower in the preserving than that in the dividing MJ group (1.4% vs. 13.0%, p = 0.017). In addition, the median postoperative hospital stay was significantly shorter in the preserving than that in the dividing MJ group (13.0 days vs. 16.0 days, p = 0.005). CONCLUSIONS: Preserving the MJ significantly reduced AL at the EJS after minimally invasive total gastrectomy for GC.

CXCR2 signaling might have a tumor-suppressive role in patients with cholangiocarcinoma.

BACKGROUND: We reported that chemokine C-X-C motif receptor 2 (CXCR2) signaling appears to play an important role in the pathogenic signaling of gastric cancer (GC), and although CXCR2 may have a role in other solid cancers, the significance of CXCR2 in cholangiocarcinoma (CCA) has not been evaluated. Herein, we determined the clinicopathologic significance of CXCL1-CXCR2 signaling in CCA. MATERIALS AND METHODS: Two human CCA cell lines, OCUG-1 and HuCCT1, were used. CXCR2 expression was examined by western blotting. We investigated the effects of CXCL1 on the proliferation (by MTT assay) and migration activity (by a wound-healing assay) of each cell line. Our immunohistochemical study of the cases of 178 CCA patients examined the expression levels of CXCR2 and CXCL1, and we analyzed the relationship between these expression levels and the patients' clinicopathologic features. RESULTS: CXCR2 was expressed on both CCA cell lines. CXCL1 significantly inhibited both the proliferative activity and migratory activity of both cell lines. CXCL1 and CXCR2 were immunohistochemically expressed in 73% and 18% of the CCA cases, respectively. The CXCL1-positive group was significantly associated with negative lymph node metastasis (p = 0.043). The CXCR2-positive group showed significantly better survival (p = 0.042, Kaplan-Meier). A multivariate logistic regression analysis revealed that CXCR2 expression (p = 0.031) and lymph node metastasis (p = 0.004) were significantly correlated with the CCA patients' overall survival. CONCLUSION: CXCR2 signaling might exert a tumor-suppressive effect on CCA cells. CXCR2 might be a useful independent prognostic marker for CCA patients after surgical resection.

EMMPRIN in extracellular vesicles from peritoneal mesothelial cells stimulates the invasion activity of diffuse-type gastric cancer cells.

Peritoneal metastasis of gastric cancer (GC) results in extremely poor prognoses. The peritoneal cavity is covered by a monolayer of peritoneal mesothelial cells (PMCs). Interactions between GC cells and PMCs might play a pivotal role in peritoneal metastasis. Extracellular vesicles (EVs) correlate with intercellular communication. Although intercellular communication between cancer cells and PMCs might be associated with the peritoneal metastatic process, the role of EVs from PMCs remains unclear. We investigated the effects of EVs from PMCs on GC cells. Three GC cell lines (OCUM-12, NUGC-3, and MKN74) and four mesothelial cell lines were used. The effects of EVs derived from the PMCs on the invasion and migration of GC cells were evaluated by Matrigel invasion assay. Factors contained in the PMC EVs were analyzed; extra-cellular matrix metalloproteinase inducer (EMMPRIN) was detected in the EVs. The effects of an EMMPRIN inhibitor on the invasion-stimulating activity of EVs were examined. The EMMPRIN expressions of 110 GCs were evaluated by immunohistochemistry. PMC EVs significantly promoted the invasion of diffuse-type GC cells, i.e., OCUM-12 and NUGC-3 cells. EMMPRIN in the EVs stimulated the invasion of OCUM-12 and NUGC-3 cells. The invasion-stimulating activity of PMC EVs was inhibited by the EMMPRIN inhibitor. A high EMMPRIN expression in PMCs was significantly associated with worse cancer-specific survival and peritoneal-recurrence-free survival. EMMPRIN in EVs from PMCs might stimulate the malignant progression of diffuse-type GC. EMMPRIN might be a useful prognostic marker of recurrence in GC patients.

Gastric cancer stem cells survive in stress environments via their autophagy system.

Cancer stem cells (CSCs) play an important role in the progression of carcinoma and have a high potential for survival in stress environments. However, the mechanisms of survival potential of CSCs have been unclear. The aim of this study was to clarify the significance of autophagy systems of CSCs under stress environments. Four gastric cancer cell line were used. Side population (SP) cells were sorted from the parent cells, as CSC rich cells. The expression of stem cell markers was examined by RT-PCR. The viability of cancer cells under starvation and hypoxia was evaluated. The expression level of the autophagy molecule LC3B-II was examined by western blot. The numbers of autophagosomes and autolysosomes were counted by electron microscope. SP cells of OCUM-12 showed a higher expression of stem cell markers and higher viability in starvation and hypoxia. Western blot and electron microscope examinations indicated that the autophagy was more induced in SP cells than in parent cells. The autophagy inhibitor significantly decreased the viability under the stress environments. These findings suggested that Cancer stem cells of gastric cancer might maintain their viability via the autophagy system. Autophagy inhibitors might be a promising therapeutic agent for gastric cancer.