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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. [ABSTRACT FROM AUTHOR]

The prognosis for patients with cancers known for a highly activated stromal reaction, including diffuse‐type (scirrhous) gastric cancer, consensus molecular subtype 4 (CMS4) colorectal cancer, and pancreatic ductal adenocarcinoma, is extremely poor. To explore the resistance of conventional therapy for those refractory cancers, detailed classification and investigation of the different subsets of cancer‐associated fibroblasts (CAFs) involved are needed. Recent studies with a single‐cell transcriptomics strategy (single‐cell RNA‐seq) have demonstrated that CAF subpopulations contain different origins and marker proteins with the capacity to either promote or suppress cancer progression. Through multiple signaling pathways, CAFs can promote tumor growth, metastasis, and angiogenesis with extracellular matrix (ECM) remodeling; they can also interact with tumor‐infiltrating immune cells and modulate the antitumor immunological state in the tumor microenvironment (TME). Here, we review the recent literature on the various subpopulations of CAFs to improve our understanding of the cell‐cell interactions in the TME and highlight future avenues for CAF‐targeted therapy. [ABSTRACT FROM AUTHOR]

Asporin (ASPN), a small leucine‐rich proteoglycan expressed predominantly by cancer associated fibroblasts (CAFs), plays a pivotal role in tumor progression. ASPN is also expressed by some cancer cells, but its biological significance is unclear. Here, we investigated the effects of ASPN expression in gastric cancer cells. Overexpression of ASPN in 2 gastric cancer cell lines, HSC‐43 and 44As3, led to increased migration and invasion capacity, accompanied by induction of CD44 expression and activation of Rac1 and MMP9. ASPN expression increased resistance of HSC‐43 cells to oxidative stress by reducing the amount of mitochondrial reactive oxygen species. ASPN induced expression of the transcription factor HIF1α and upregulated lactate dehydrogenase A (LDHA) and PDH‐E1α, suggesting that ASPN reprograms HSC‐43 cells to undergo anaerobic glycolysis and suppresses ROS generation in mitochondria, which has been observed in another cell line HSC‐44PE. By contrast, 44As3 cells expressed high levels of HIF1α in response to oxidant stress and escaped apoptosis regardless of ASPN expression. Examination of xenografts in the gastric wall of ASPN–/– mice revealed that growth of HSC‐43 tumors with increased micro blood vessel density was significantly accelerated by ASPN; however, ASPN increased the invasion depth of both HSC‐43 and 44As3 tumors. These results suggest that ASPN has 2 distinct effects on cancer cells: HIF1α‐mediated resistance to oxidative stress via reprogramming of glucose metabolism, and activation of CD44‐Rac1 and MMP9 to promote cell migration and invasion. Therefore, ASPN may be a new therapeutic target in tumor fibroblasts and cancer cells in some gastric carcinomas. [ABSTRACT FROM AUTHOR]

It has been reported that circulating tumor cells (CTCs) are beneficial for predicting tumor stage or treatment response. Although epithelial cell adhesion molecules (EpCAMs) and cytokeratin (CK) have been often used for the identification of CTCs, other tumor markers have not been fully investigated as detecting tools for CTCs. Thus, this study aims to clarify the significance of carcinoembryonic antigen (CEA, CD66e)‐positive CTCs in patients with gastric cancer. A total of 150 patients with gastric cancer were enrolled in this study. The mononuclear fraction of peripheral blood was enriched by Ficoll. The number of cells was enumerated depending on the positivity of EpCAM and CEA or CK by flow cytometry. The association of these cells with clinicopathologic characteristics was investigated. The mean age was 70 (range 28–92). The macroscopic type of gastric cancer was classified as 0/1/2/3/4/5 in 59/11/22/38/16/4 patients, respectively. Seventy‐one patients (47.3%) were diagnosed with intestinal‐type cancer, while 76 patients (50.7%) were diagnosed with the diffuse type. The mean numbers of cells with EpCAM−CK+, EpCAM+CK−, EpCAM+CK+, EpCAM−CEA+, EpCAM+CEA−, and EpCAM+CEA+ were 618, 237, 19.9, 1147, 291, and 7.41, respectively. The number of EpCAM−CEA+cells was significantly higher in patients with stage II–III and IV than in patients with stage I. The 3‐year RFS rate in patients with a high number of EpCAM−CEA+cells (>=622) was 57.5%, while it was 79.3% in patients with a low number of EpCAM−CEA+cells (<622) (log‐rank p = 0.0079). Thus, we conclude that CEA‐positive CTCs will be a clinically beneficial biomarker in patients with gastric cancer. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Metastatic cancers commonly activate adaptive chemotherapy resistance, attributed to both microenvironment‐dependent phenotypic plasticity and genetic characteristics of cancer cells. However, the contribution of chemotherapy itself to the non‐genetic resistance mechanisms was long neglected. Using high‐grade serous ovarian cancer (HGSC) patient material and cell lines, we describe here an unexpectedly robust cisplatin and carboplatin chemotherapy‐induced ERK1/2‐RSK1/2‐EphA2‐GPRC5A signaling switch associated with cancer cell intrinsic and acquired chemoresistance. Mechanistically, pharmacological inhibition or knockdown of RSK1/2 prevented oncogenic EphA2‐S897 phosphorylation and EphA2‐GPRC5A co‐regulation, thereby facilitating a signaling shift to the canonical tumor‐suppressive tyrosine phosphorylation and consequent downregulation of EphA2. In combination with platinum, RSK inhibitors effectively sensitized even the most platinum‐resistant EphA2high, GPRC5Ahigh cells to the therapy‐induced apoptosis. In HGSC patient tumors, this orphan receptor GPRC5A was expressed exclusively in cancer cells and associated with chemotherapy resistance and poor survival. Our results reveal a kinase signaling pathway uniquely activated by platinum to elicit adaptive resistance. They further identify GPRC5A as a marker for abysmal HGSC outcome and putative vulnerability of the chemo‐resistant cells to RSK1/2‐EphA2‐pS897 pathway inhibition. Synopsis: Platinum chemotherapy induces RSK1/2‐EphA2‐GPRC5A oncogenic signaling switch associated to intrinsic and acquired resistance. This study identifies GPRC5A as a marker for poor therapy response and vulnerability of the resistant cells to RSK1/2‐EphA2‐pS897 pathway inhibition in ovarian cancer. The oncogenic switch is mediated by platinum‐activated ERK1/2‐RSK1/2 pathway coupled with co‐localization of EphA2 and the EphA2‐interacting orphan receptor GPRC5A.RSK inhibition impairs, through EphA2‐pY588 activation and consequent EphA2 downregulation, the platinum‐induced resistance‐associated GPRC5A‐EphA2‐pS897 co‐regulation, thus sensitizing HGSC cell to platinum.GPRC5A expression is associated with HGSC cell sensitivity to RSKi‐platinum combination treatment ex vivo.In human HGSC tumors, high GPRC5A levels are correlated with poor treatment response, as well as adverse overall and progression‐free patient survival. Combined EphA2‐GPRC5A expression predict shorter progression‐free survival. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinase 14 (MMP14), a membrane‐associated matrix metalloproteinase, has been shown to influence the invasion and metastasis of several solid tumors. Prospero homeobox protein 1 (PROX1), involved in the development and cell fate determination, is also expressed in malignant diseases functioning either as a tumor‐suppressing or oncogenic factor. In certain cancers PROX1 appears to transcriptionally suppress MMP14 expression. This study, therefore, aimed to explore the association between MMP14 and PROX1 and understand their potential as prognostic biomarkers in gastric cancer. The cohort consisted of 313 individuals operated for gastric adenocarcinoma between 2000 and 2009 in the Department of Surgery, Helsinki University Hospital. MMP14 and PROX1 expressions were studied using immunohistochemistry in the patient sample and using immunoblotting and immunofluorescence in gastric cancer cell lines. We generated survival curves using the Kaplan‐Meier method, determining significance via the log‐rank test. A high MMP14 expression associated with being ≥67 years (P = .041), while a positive nuclear PROX1 expression associated with tumors of a diffuse histological type (P = .041) and a high cytoplasmic PROX1 expression (P < .001). Five‐year disease‐specific survival among patients with a high MMP14 expression was 35.9% (95% confidence interval [CI] 24.9‐46.9), compared to 45.3% (95% CI 38.0‐52.6) for patients with a low MMP14 (P = .030). Survival was worse specifically among those with a high MMP14 and absent nuclear PROX1 expression (hazard ratio [HR] 1.65; 95% CI 1.09‐2.51; P = .019). Thus, this study confirms that a high MMP14 expression predicts a worse survival in gastric cancer, revealing for the first time that survival is particularly worse when PROX1 is low. [ABSTRACT FROM AUTHOR]

Scirrhous‐type gastric cancer (SGC) is one of the most intractable cancer subtypes in humans, and its therapeutic targets have been rarely identified to date. Exploration of somatic mutations in the SGC genome with the next‐generation sequencers has been hampered by markedly increased fibrous tissues. Thus, SGC cell lines may be useful resources for searching for novel oncogenes. Here we have conducted whole exome sequencing and RNA sequencing on 2 SGC cell lines, OCUM‐8 and OCUM‐9. Interestingly, most of the mutations thus identified have not been reported. In OCUM‐8 cells, a novel CD44‐IGF1R fusion gene is discovered, the protein product of which ligates the amino‐terminus of CD44 to the transmembrane and tyrosine‐kinase domains of IGF1R. Furthermore, both CD44 and IGF1R are markedly amplified in the OCUM‐8 genome and abundantly expressed. CD44‐IGF1R has a transforming ability, and the suppression of its kinase activity leads to rapid cell death of OCUM‐8. To the best of our knowledge, this is the first report describing the transforming activity of IGF1R fusion genes. However, OCUM‐9 seems to possess multiple oncogenic events in its genome. In particular, a novel BORCS5‐ETV6 fusion gene is identified in the OCUM‐9 genome. BORCS5‐ETV6 possesses oncogenic activity, and suppression of its message partially inhibits cell growth. Prevalence of these novel fusion genes among SGC awaits further investigation, but we validate the significance of cell lines as appropriate reagents for detailed genomic analyses of SGC. [ABSTRACT FROM AUTHOR]

Exosomes are small (30–100 nm) membrane vesicles that serve as regulatory agents for intercellular communication in cancers. Currently, exosomes are detected by immuno‐based assays with appropriate pretreatments like ultracentrifugation and are time consuming (>12 h). We present a novel pretreatment‐free fluorescence‐based sensing platform for intact exosomes, wherein exchangeable antibodies and fluorescent reporter molecules were aligned inside exosome‐binding cavities. Such antibody‐containing fluorescent reporter‐grafted nanocavities were prepared on a substrate by well‐designed molecular imprinting and post‐imprinting modifications to introduce antibodies and fluorescent reporter molecules only inside the binding nanocavities, enabling sufficiently high sensitivity to detect intact exosomes without pretreatment. The effectiveness of the system was demonstrated by using it to discriminate between normal exosomes and those originating from prostate cancer and analyze exosomes in tear drops. Making a good impression: A novel pretreatment‐free fluorescence‐based sensing platform for intact exosomes was prepared by using molecular imprinting and post‐imprinting modifications, in which exchangeable antibodies and fluorescent reporter molecules were aligned only inside exosome‐binding cavities. The resulting high sensitivity enabled exosome detection without sample pretreatment. The system was used to distinguish cancer‐secreted exosomes from normal ones. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the significance of glucose metabolism-related enzymes in the proliferation of gastric cancer under hypoxia. Four hypoxia-resistant gastric cancer cell lines and four parent cell lines were used. Reverse transcription-PCR was used to evaluate the mRNA expression levels of the following metabolism-related enzymes: pyruvate kinase isozyme M2 (PKM2), glutaminase (GLS), enolase 1 (ENO1), glucose-6-phosphate dehydrogenase (G6PDH), and PKM1. The effects of these enzymes on the proliferation of gastric cancer cells were examined using siRNAs, shikonin as a PKM2 inhibitor, or BPTES as a GLS inhibitor, in vitro and in vivo. Levels of both PKM2 and GLS mRNA were significantly high in all hypoxia-resistant cell lines, compared with those of their parent cells. Knockdown of PKM2 and GLS significantly decreased the proliferation of all hypoxia-resistant cells. The combination of siPKM2 and siGLS significantly decreased proliferation compared with treatment by siPKM2 or siGLS alone. The knockdown of ENO1, G6PDH, or PKM1 did not decrease the proliferation of all hypoxia-resistant cells. Combination treatment using shikonin and BPTES inhibited the proliferation of all hypoxia-resistant cancer cells more than that by either agent alone. The in vivo study indicated that the tumor size treated by the combination of shikonin and BPTES was significantly smaller than that of vehicle-treated group. These findings suggested that PKM2 and GLS might play important roles in the proliferation of hypoxic gastric cancer cells. A combination of PKM2 and GLS inhibitors could be therapeutically promising for the treatment of gastric cancer. [ABSTRACT FROM AUTHOR]

Tumor lymphangiogenesis is a major prognostic indicator of gastric cancer. Tumor-induced inflammation has been shown to attract tumor-associated macrophages that affect lymphangiogenesis. However, detailed mechanisms of macrophage-induced lymphangiogenesis have not been elucidated. Here, we evaluated the interaction between tumor-associated macrophages and lymphatic endothelial cells ( LECs) derived from lymph nodes ( LNs) of human gastric cancer. Lymphatic endothelial cells were directly or indirectly cocultured with macrophages from healthy human blood, with or without the supernatant of the gastric cancer cell line, OCUM-12. We analyzed the effect of cancer pretreated macrophages and of macrophages from metastatic LNs of gastric cancer on LECs. We observed morphological changes of LECs in coculture and assessed the gene expression of possible lymphangiogenic molecules of macrophages and LECs after contact coculture, and of cancer pretreated macrophages, by quantitative RT- PCR. Specimens of metastatic LN of gastric cancer were immunofluorescently stained. We found that tubulogenesis of LECs was observed only in the contact coculture model. OCUM-12 cells promoted macrophage-induced tubulogenesis of LECs. Relative gene expression of MMP and adhesion molecules was significantly upregulated in both capillary-forming LECs and cocultured macrophages. Cancer pretreated macrophages upregulated lymphangiogenic factors including inflammatory cytokines, MMPs, adhesion molecules, and vascular endothelial growth factor-C. Blocking of intercellular adhesion molecule-1 and macrophage activation suppressed tubulogenesis of LECs. Immunohistochemistry showed macrophages localized around lymphatic vessels. Our results suggested that interaction between LECs and macrophages may be an important initial step of tumor lymphangiogenesis developing LN metastasis. Understanding of its mechanisms could be useful for future therapeutics of gastric cancer. [ABSTRACT FROM AUTHOR]

Cancer tissues have biological characteristics similar to those observed in embryos during development. Many types of cancer cells acquire pro-invasive ability through epithelial-mesenchymal transition ( EMT). Similar processes (gastrulation and migration of cranial neural crest cells [ CNCC]) are observed in the early stages of embryonic development in Xenopus during which cells that originate from epithelial sheets through EMT migrate to their final destinations. The present study examined Xenopus embryonic tissues to identify anti-cancer compounds that prevent cancer invasion. From the initial test of known anti-cancer drugs, AMD3100 (an inhibitor of CXCR4) and paclitaxel (a cytoskeletal drug targeting microtubules) effectively prevented migration during gastrulation or CNCC development. Blind-screening of 100 synthesized chemical compounds was performed, and nine candidates that inhibited migration of these embryonic tissues without embryonic lethality were selected. Of these, C-157 (an analog of podophyllotoxin) and D-572 (which is an indole alkaroid) prevented cancer cell invasion through disruption of interphase microtubules. In addition, these compounds affected progression of mitotic phase and induced apoptosis of SAS oral cancer cells. SAS tumors were reduced in size after intratumoral injection of C-157, and peritoneal dissemination of melanoma cells and intracranial invasion of glioma cells were inhibited by C-157 and D-572. When the other analogues of these chemicals were compared, those with subtle effect on embryos were not tumor suppressive. These results suggest that a novel chemical-screening approach based on Xenopus embryos is an effective method for isolating anti-cancer drugs and, in particular, targeting cancer cell invasion and proliferation. [ABSTRACT FROM AUTHOR]

Mammalian target of rapamycin (mTOR) is a serine-threonine kinase that acts downstream of the phosphatidylinositol 3-kinase signaling pathway and regulates a wide range of cellular functions including transcription, translation, proliferation, apoptosis, and autophagy. Whereas genetic alterations that result in mTOR activation are frequently present in human cancers, whether the mTOR gene itself becomes an oncogene through somatic mutation has remained unclear. We have now identified a somatic non-synonymous mutation of mTOR that results in a leucine-to-valine substitution at amino acid position 2209 in a specimen of large cell neuroendocrine carcinoma. The mTOR(L2209V) mutant manifested marked transforming potential in a focus formation assay with mouse 3T3 fibroblasts, and it induced the phosphorylation of p70 S6 kinase, S6 ribosomal protein, and eukaryotic translation initiation factor 4E-binding protein 1 in these cells. Examination of additional tumor specimens as well as public and inhouse databases of cancer genome mutations identified another 28 independent non-synonymous mutations of mTOR in various cancer types, with 12 of these mutations also showing transforming ability. Most of these oncogenic mutations cluster at the interface between the kinase domain and the FAT (FRAP, ATM, TRRAP) domain in the 3-D structure of mTOR. Transforming mTOR mutants were also found to promote 3T3 cell survival, and their oncogenic activity was sensitive to rapamycin. Our data thus show that mTOR acquires transforming activity through genetic changes in cancer, and they suggest that such tumors may be candidates for molecularly targeted therapy with mTOR inhibitors. [ABSTRACT FROM AUTHOR]

The antitumor activity of prostaglandin (PG) D2 has been demonstrated against some types of cancer, including gastric cancer. However, exogenous PGD2 is not useful from a clinical point of view because it is rapidly metabolized in vivo. The aim of this study was to clarify the antitumor efficacy of an alternative, PGD synthase (PGDS), on gastric cancer cells. The effects of PGD2 and PGDS on the proliferation of gastric cancer cells were examined in vivo and in vitro. The expression levels of PGD2 receptors and peroxisome proliferator-activated receptor γ (PPARγ) were evaluated by RT-PCR. The effects of a PPARγ antagonist or siPPARγ on the proliferation of cancer cells and the c-myc and cyclin D1 expression were examined in the presence or absence of PGD2 or PGDS. PPARγ was expressed in gastric cancer cell lines, but PGD2 receptors were not. PGD2 and PGDS significantly decreased the proliferation of gastric cancer cells that highly expressed PPARγ. PGDS increased the PGD2 production of gastric cancer cells. A PPARγ antagonist and siPPARγ transfection significantly suppressed the growth-inhibitory effects of PGD2 and PGDS. Expression of c-myc and cyclin D1 was significantly decreased by PGD2; this inhibitory effect was suppressed by PPARγ antagonist. Both PGD2 and PGDS significantly decreased subcutaneous tumor growth in vivo. Tumor volume after PGDS treatment was significantly less than PGD2 treatment. These findings suggest that PGDS and PGD2 decrease the proliferation of gastric cancer cells through PPARγ signaling. PGDS is a potentially promising therapeutic agent for gastric cancers that express PPARγ. [ABSTRACT FROM AUTHOR]

Cancer-associated fibroblasts (CAFs) have recently been implicated in tumor growth and metastasis in gastric cancer. Cancer stem cells (CSCs) have been proposed to have an important role in cancer progression. The aim of this study was to clarify the effect of CAFs on CSCs characteristics in gastric carcinoma. Scirrhous gastric cancer cell lines, OCUM-12 and OCUM-2MD3, and non-scirrhous gastric cancer cell lines, MKN-45 and MKN-74, were used. OCUM-12/side population (SP) cells and OCUM-2MD3/SP cells were sorted by flow cytometry as CSC-rich cells from the parent cells. CaF-37 was established from the tumoral gastric specimens as CAFs. Flow cytometric analysis of SP fraction, spheroid colony assay, and RT-PCR analysis of CSC markers were performed to identify CSCs properties. Effect of CAFs on the tumorigenicity by OCUM-12/SP cells was examined using nude mice. CAF CM significantly increased the percentages of the SP fraction of OCUM-12/SP and OCUM-2MD3/SP cells, but not that of MKN-45/SP and MKN-74/SP cells. Taken together, CM from CaF-37 significantly increased the number of spheroid colonies and the expression level of CSC markers of OCUM-12/SP and OCUM-2MD3/SP cells. These stimulating-activities by CM were significantly decreased by TGFβ inhibitors, but not FGFR and cMet inhibitor. Tumorigenicity by subcutaneous coinoculation of OCUM-12/SP cells with CAFs was significantly high in comparison with that by OCUM-12/SP cells alone. Phospho-Smad2 expression level was significantly increased by co-inoculation with CAFs. These findings suggested that CAFs might regulate the stemness of CSCs in scirrhous gastric cancer by TGFβ signaling. [ABSTRACT FROM AUTHOR]

Gastric cancer ( GC) is one of the most common malignancies worldwide. In particular, scirrhous type GC is highly metastatic and is characterized clinically by rapid disease progression and poor prognosis. Micro RNAs (mi RNAs) play crucial roles in cancer development and progression. In the present study, we identified several mi RNAs that are expressed at higher levels in scirrhous type GC than in non-scirrhous type GC by mi RNA microarray analysis. Among these, micro RNA-143 (miR-143) expression was higher in scirrhous type GC than in non-scirrhous types of GC. In situ hybridization and quantitative RT- PCR analysis showed that miR-143 is expressed by stromal fibroblasts but not by cancer cells. In stromal cells, miR-143 enhanced collagen type III expression in normal gastric fibroblasts and cancer-associated fibroblasts through activation of transforming growth factor-β)/ SMAD signaling. Furthermore, high miR-143 expression in GC was associated with worse cancer-specific mortality ( P = 0.0141). Multivariate analysis revealed that miR-143 was an independent prognostic factor. Treatment of GC cell lines with 5-aza-2′-deoxycytidine restored the expression of miR-143, and precursor miR-143 caused the inhibition of cancer cell invasion. These data suggest that miR-143 regulates fibrosis of scirrhous type GC through induction of collagen expression in stromal fibroblasts and that miR-143 expression serves as a prognostic marker of GC. [ABSTRACT FROM AUTHOR]

Human epidermal growth factor receptor 2 ( HER2) amplification occurs in approximately 20% of gastric and gastroesophageal junction cancers in the United States and European Union. Lapatinib, a dual HER2 and epidermal growth factor receptor tyrosine kinase inhibitor, has demonstrated clinical efficacy in HER2-amplified cancer cells. However, several studies have shown that some cytokines can mediate resistance to lapatinib using their receptor tyrosine kinase ( RTK) pathways. One of these, Heregulin1 ( HRG1), can confer resistance to lapatinib-mediated growth inhibition in HER2-amplified breast cancer cells, but the underlying mechanisms remain unknown. Here, we investigated whether and how HRG1 causes resistance to lapatinib in gastric and gastroesophageal junction cancers in vitro. HER2-amplified gastric and gastroesophageal junction cancer cell lines were highly sensitive to lapatinib. Exposure to HRG1 together with lapatinib rescued cells from lapatinib-induced cell cycle arrest and apoptosis. Downregulation of HER3 with si RNA in the presence of HRG1 re-sensitized HER2-amplified cancer cells to lapatinib. Immunoblotting analysis indicated that HRG1 re-activated HER3 and AKT in the presence of lapatinib, which persisted for at least 72 h. Activation of HER3 and downstream AKT was mediated by residual activity of HER2. HRG1-mediated resistance could be reduced by PI3 K/m TOR inhibitors or by complete inhibition of HER2. Thus, we conclude that HRG1 mediates resistance to lapatinib through HER3 and AKT activation, and that this depends on residual HER2 activity. Lapatinib in combination with anti- PI3 K therapies or more potent HER2 inhibitors would improve the efficacy and avoid the emergence of resistant cells. [ABSTRACT FROM AUTHOR]

Aldehyde dehydrogenase 1 (ALDH1) has been shown to serve as a marker for cancer-initiating cells (CICs), but little is known about the regulation of the CIC functions of ALDH1+ cancer cells. We isolated ALDH1+ cells from human diffuse-type gastric carcinoma cells and characterized these cells using an Aldefluor assay. ALDH1+ cells constituted 5-8% of the human diffuse-type gastric carcinoma cells, OCUM-2MLN and HSC-39; were more tumourigenic than ALDH1− cells; and were able to self-renew and generate heterogeneous cell populations. Using gene expression microarray analyses, we identified REG4 ( regenerating islet-derived family, member 4) as one of the genes up-regulated in ALDH1+ cells, and thus as a novel marker for ALDH1+ tumour cells. Induced expression of REG4 enhanced the colony-forming ability of OCUM-2MLN cells, while knockdown of REG4 inhibited the tumourigenic potential of ALDH1+ cells. We further found that TGF-β signalling reduces the expression of ALDH1 and REG4, and the size of the ALDH1+ cell population. In human diffuse-type gastric carcinoma tissues, the expression of ALDH1 and REG4 correlated with each other, as assessed by immunohistochemistry, and ALDH1 expression correlated inversely with Smad3 phosphorylation as a measure of TGF-β signalling. These findings illustrate that, in diffuse-type gastric carcinoma, REG4 is up-regulated in ALDH1+ CICs, and that the increased tumourigenic ability of ALDH1+ cells depends on REG4. Moreover, TGF-β down-regulates ALDH1 and REG4 expression, which correlates with a reduction in CIC population size and tumourigenicity. Targeting REG4 in ALDH1+ CICs may provide a novel strategy in the treatment of diffuse-type gastric carcinoma. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Tumor progression has been recognized as the product of evolving crosstalk between cancer cells and the surrounding stromal cells. Cancer-associated orthotopic myofibroblasts may be linked to the progression of gastric carcinomas. To understand the significance of orthotopic myofibroblasts, we examined the effects of cancer-associated orthotopic myofibroblasts on the malignant phenotype of gastric cancer cells. Three human gastric cancer cell lines ( OCUM-2 MD3, OCUM-12, MKN-45) and four human gastric fibroblast cell lines (cancer-associated orthotopic fibroblast [ Ca F]-29, Ca F-33, normal orthotopic fibroblast [ NF]-29, NF-33) were used. The cancer-associated orthotopic fibroblast cell lines Ca F-29 and Ca F-33 were established from a tumoral gastric wall, and normal orthotopic fibroblast NF-29 and NF-33 were established from a non-tumoral gastric wall. Fibroblasts that were α-smooth muscle actin-positive were defined as myofibroblasts. We examined the effects of cancer-associated orthotopic myofibroblasts on the aggressiveness of gastric cancer cells by wound-healing assay, invasion assay, and RT- PCR. The ratios of myofibroblasts in Ca F-29 (33%) and Ca F-33 (46%) were significantly ( P < 0.001) greater than those in NF-29 (11%) or NF-33 (13%). Although all four orthotopic fibroblast lines increased the motility of gastric cancer cells, including migration and invasion ability, the motility-stimulating activity of cancer-associated fibroblasts ( Ca F-29 and Ca F-33) was significantly higher than that of normal fibroblasts ( NF-29 and NF-33). These motility-stimulating activities of cancer-associated orthotopic fibroblasts were downregulated by Smad2 si RNA treatment and anti-transforming growth factor-β neutralizing antibody. These findings suggest that cancer-associated orthotopic myofibroblasts may play an important role in the progression of gastric cancers and that transforming growth factor-β produced by myofibroblasts may be one of the factors associated with the aggressiveness of gastric carcinoma cells. ( Cancer Sci 2012; 103: 797-805) [ABSTRACT FROM AUTHOR]

Cancer metastasis remains the primary cause of pain, suffering, and death in cancer patients, and even the most current therapeutic strategies have not been highly successful in preventing or inhibiting metastasis. In most patients with scirrhous gastric cancer (one of the most aggressive of diffuse-type gastric cancer), recurrence occurs even after potentially curative resection, most frequently in the form of peritoneal metastasis. Given that the occurrence of diffuse-type gastric cancers has been increasing, the development of new strategies to combat metastasis of this disease is critically important. Plasminogen activator inhibitor-1 (PAI-1) is a critical factor in cancer progression; thus, PAI-1 RNAi may be an effective therapy against cancer metastasis. In the present study, we used an RNAi technique to reduce PAI-1 expression in an in vivo model system for gastric cancer metastasis. Ex vivo plasmid transfection and adenovirus infection were tested as mechanisms to incorporate specific PAI-1 RNAi vectors into human gastric carcinoma cells. Both approaches significantly decreased peritoneal tumor growth and the formation of bloody ascites in the mouse model, suggesting that this approach may provide a new, effective strategy for inhibiting cancer metastasis. ( Cancer Sci 2012; 103: 228-232) [ABSTRACT FROM AUTHOR]

ERas is a recently identified oncogene involved in the tumorgenic growth of embryonic stem cells. We examined the significance of ERas expression in scirrhous gastric carcinoma, and the possibility of ERas as a tumor-associated antigen of gastric cancer for developing a cancer vaccine. ERas expression was determined in scirrhous gastric carcinoma specimens by immunohistochemical staining. To assess the possibility of the ERas protein as an anticancer vaccine target, we examined whether ERas for HLA-A-restricted epitope peptides were capable of eliciting cytotoxic T lymphocyte activity. Immunohistochemical analysis identified ERas protein in the nucleus and cytoplasm of cancer cells, yet ERas was not expressed in normal gastric epithelium. By western blotting, lysates of the scirrhous gastric cancer cell lines, OCUM-8, OCUM-2MD3 and OCUM-2M were shown to contain a 25-kDa band of ERas protein. ERas mRNA was detected in these cell lines by RT-PCR. To investigate cytotoxicity, we successfully established cytotoxic T lymphocyte clones stimulated by HLA-A*2402-restricted ERas peptides (FALDDPSSL). These peptides have specific cytotoxicity against corresponding HLA-A*2402-positive target cells pulsed with the candidate peptide. We found that the cytotoxic T lymphocyte clones demonstrated cytotoxic activity against OCUM-8 cells that endogenously express ERas. Our results suggest that ERas is a novel tumor-associated antigen with the potential application to be a vaccine against scirrhous gastric cancer. ( Cancer Sci 2011; 102: 683-689) [ABSTRACT FROM AUTHOR]

Transforming growth factor-β (TGF-β) signals are closely associated with the distant metastases of gastric cancer. The aim of this study was to clarify the effect of a TGF-β receptor I (TβR-I) phosphorylation inhibitor, Ki26894, in combination with anticancer drugs, on the lymph node (LN) metastasis of scirrhous gastric cancer. A novel TβR-I kinase inhibitor, Ki26894, inhibits the phosphorylation of Smad2 at the ATP binding site of TβR-I. S1 is a 5-fluorouracil analog. The human scirrhous gastric cancer cell line OCUM-2MLN and the human gastric fibroblasts NF-33 were used. OCUM-2MLM cells in the upper well and NF-33 cells in the lower well were co-incubated with or without Ki26894. The proliferation of OCUM-2MLN cells was significantly stimulated by co-culture with NF-33 cells. Ki26894 significantly suppressed the growth interactions between OCUM-2MLN cells and NF-33 cells. Gastric cancer models established by orthotopic inoculation of OCUM-2MLN cells showed diffusely infiltrating gastric adenocarcinoma accompanied by LN metastases. We divided these mice into four groups, (control vehicle, Ki26894, S1, Ki26894 plus S1), and examined the effect of Ki26894 and/or S1 on phosphorylation of Smad2, tumor size, LN metastases, and lymphatic involvements. Ki26894 inhibited the Smad2 phosphorylation of cancer cells and decreased the extent of lymphatic involvement, compared with the control or S1 only group. The Ki26894 plus S1 administration group significantly suppressed tumor growth and decreased LN metastasis more effectively than either alone. These findings suggested that the TβR-I kinase inhibitor with S1 is useful for the treatment of scirrhous gastric carcinoma with LN metastasis. ( Cancer Sci 2010) [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factor receptors (VEGFRs) are mainly expressed by endothelial cells, but they are also expressed by some cancer cells, including pancreatic cancer. The objective of this study was to evaluate the significance of VEGFRs expression in pancreatic cancer cells. A total of 107 primary pancreatic tumors were stained with antibodies against VEGFR-1, VEGFR-2, phospho-VEGFR-2 (pVEGFR-2), VEGFR-3, VEGF-A, VEGF-C, and VEGF-D. VEGFR-2 and pVEGFR-2 expression were positive in 74 (69%) and 54 (50%) of 107 pancreatic cancers. There was a significant correlation ( P < 0.001) between VEGFR-2 expression and pVEGFR-2 expression. pVEGFR-2 was significantly associated with invasion to the anterior capsule of pancreas ( P = 0.032) and arterial invasion ( P = 0.012). In contrast, VEGFR-1 and VEGFR-3 expression was only observed in 13 (12%) and 15 (14%) of 107 pancreatic cancers, and was not associated with any clinicopathological features. The prognosis of pVEGFR-2 positive patients with stage IIA tumors was significantly ( P = 0.0441) poorer than that of pVEGFR-2-negative patients. VEGF-A, VEGF-C, and VEGF-D expression was positive in 42 (39%), 82 (77%), and 39 (36%) of 107 pancreatic cancers, respectively. The prognosis for VEGF-A-positive patients was significantly ( P = 0.0425) poor, but not for VEGF-C-positive and VEGF-D-positive patients. A multivariate analysis indicated pVEGFR-2 expression to be an independent prognostic factor, but not VEGF-A. These findings suggested that VEGFR-2 signaling might therefore be associated with the prognosis of patients with pancreatic cancer. The expression of pVEGFR-2 might be a novel predictive prognostic marker for patients with pancreatic cancers, especially at clinical stage IIA. ( Cancer Sci 2010) [ABSTRACT FROM AUTHOR]

Lapatinib is a small molecule inhibitor of both HER2 and the epidermal growth factor receptor (EGFR). We investigated the effect of treatment with lapatinib alone or in combination with a fluoropyrimidine derivative S-1 against pancreatic cancer. The HER2/EGFR expression in each of the four pancreatic cancer cell lines MiaPaca-2, PANC-1, Capan-1 and Capan-2 was measured by flow cytometry. The anti-tumor effects of lapatinib (30 mg/kg) and/or S-1 (10 mg/kg) were evaluated using female BALB/c nude mice xenografts generated using these four cell lines. Synergy between lapatinib and S-1 was examined by median effect analysis in vitro. Resected pancreatic cancer tissues from 137 patients were immunohistochemically stained with anti-human HER2 and EGFR antibodies. The administration of lapatinib as a single agent substantially suppressed tumor growth in vivo of all pancreatic cancer cell lines examined. A strong correlation was observed between HER2 expression and the anti-tumor effect of lapatinib in vivo. Lapatinib synergized with S-1 to inhibit the tumor growth of MiaPaca-2 and PANC-1 xenografts. When used as a single agent in vitro, lapatinib barely inhibit the cell growth of any cell line. However, lapatinib synergized with the anti-tumor activity of the S-1 components 5-fluorouracil and 5-chloro-2,4-dihydrogenase against all cell lines. Immunohistochemical staining demonstrated that 70% of the pancreatic cancers overexpressed HER2 and/or EGFR. Both lapatinib monotherapy and combined treatment with S-1 may be promising treatments for patients with pancreatic cancers; the majority these cancers express lapatinib target molecules. ( Cancer Sci 2009; 00: 000–000) [ABSTRACT FROM AUTHOR]

The aim of this study is to clarify the benefit of combination chemotherapy in gastric cancer based on a cell-signal inhibitor and an anticancer drug. Two scirrhous gastric cancer cell lines and two non-scirrhous gastric cancer cell lines were used. Five anticancer drugs (5-fluorouracil [5FU], paclitaxel, oxaliplatin, irinotecan, and gemcitabine) and four cell-signal inhibitors, mammalian target of rapamycin (mTOR) inhibitor, glycogen synthase kinase 3β, p38αβMAPK, and cyclin-dependent kinase, were used. The proliferation of cancer cells was examined by MTT assay and in vivo study. The apoptosis of cancer cells and the expression of apoptosis-related molecules were examined by flow cytometry, real-time PCR, and immunostaining. mTOR inhibitors with 5FU showed a synergistic antiproliferative effect in scirrhous gastric cancer, whereas the other signal inhibitors showed no synergistic effect with any anticancer drugs. mTOR inhibitor decreased the IC50 of 5FU and increased the apoptosis rate in scirrhous gastric cancer cells, but not in non-scirrhous gastric cancer cells. The pan-caspase inhibitor, zVAD-fmk, inhibits apoptosis induced in combination with 5FU and mTOR inhibitor. mTOR inhibitor decreased dihydropyrimidine dehydrogenase, thymidylatesynthase, and bcl-2expression, and increased caspase-3 and p21 expression of scirrhous gastric cancer cells, but did not affect those of non-scirrhous gastric cancer cells. In an in vivo study, mTOR inhibitor significantly enhanced the therapeutic efficacy of S1, an analog of 5FU. These findings suggest that mTOR inhibitor interacts with 5FU in a synergistic manner in scirrhous gastric cancer cells by the activation of the apoptosis signal. Therefore, mTOR inhibitor is a promising therapeutic agent in combination with 5FU in scirrhous gastric cancer. ( Cancer Sci 2009; 100: 2402–2410) [ABSTRACT FROM AUTHOR]

c-Ski, originally identified as a proto-oncogene product, is an important negative regulator of transforming growth factor (TGF)-β family signaling through interaction with Smad2, Smad3, and Smad4. High expression of c-Ski has been found in some cancers, including gastric cancer. We previously showed that disruption of TGF-β signaling by dominant-negative TGF-β type II receptor in a diffuse-type gastric carcinoma model accelerated tumor growth through induction of tumor angiogenesis by decreased expression of the anti-angiogenic factor thrombospondin (TSP)-1. Here, we examined the function of c-Ski in human diffuse-type gastric carcinoma OCUM-2MLN cells. Overexpression of c-Ski inhibited TGF-β signaling in OCUM-2MLN cells. Interestingly, c-Ski overexpression resulted in extensive acceleration of the growth of subcutaneous xenografts in BALB/c nu/nu female mice (6 weeks of age). Similar to tumors expressing dominant-negative TGF-β type II receptor, histochemical studies revealed less fibrosis and increased angiogenesis in xenografted tumors expressing c-Ski compared to control tumors. Induction of TSP-1 mRNA by TGF-β was attenuated by c-Ski in vitro, and expression of TSP-1 mRNA was decreased in tumors expressing c-Ski in vivo. These findings suggest that c-Ski overexpression promotes the growth of diffuse-type gastric carcinoma through induction of angiogenesis. ( Cancer Sci 2009; 100: 1809–1816) [ABSTRACT FROM AUTHOR]

Cancer stem cells (CSCs) are considered to be responsible for cancer metastasis, but the evidence to conclusively prove this hypothesis remains uncertain. The side population (SP), as evaluated by a flow cytometric analysis using Hoechst 33342, has been known as CSC-rich population. The aim of this study was to clarify the characterization of the SP cells in peritoneal metastasis of gastric carcinoma. Gastric cancer cell lines OCUM-2M, OCUM-2D, and OCUM-2MD3 (a daughter cell line with high potential for peritoneal metastasis) were used. We isolated SP cells from OCUM-2M and OCUM-2D using flow cytometry. Serial sorting was performed three times to enrich SP cells, and they were designated as OCUM-2M/SP and OCUM-2D/SP cells. Flow cytometric analysis showed 0.46%, 0.29%, 5.24%, 6.49%, and 11.3% of the SP cells to be found in OCUM-2M, OCUM-2D, OCUM-2MD3, OCUM-2M/SP, and OCUM-2D/SP cells, respectively. The intraperitoneal inoculation of SP cells and OCUM-2MD3 cells produced peritoneal metastasis, but parent cells did not. The adhesion ability of SP and OCUM-2MD3 cells was significantly high in comparison to that of parent cells. The expression level of adhesion molecules α2-, α5-, β3-, and β5-integrin, and CD44, was high in SP cells compared to parent cells. The expression of stemness markers, Oct3/4 and Sox2, increased in the SP-cell-injected tumors. These findings suggested that CSC-like SP cells expressing α2-, α5-, β3-, and β5-integrin, and CD44, may play an important role for peritoneal metastasis in gastric carcinoma. Oct3/4 and Sox2 may be associated with CSC in gastric cancer. ( Cancer Sci 2009) [ABSTRACT FROM AUTHOR]

HER2 overexpression has been linked to clinical outcomes in several solid tumors, such as breast cancer. However, the correlation between HER2 overexpression and survival in pancreatic carcinoma remains unclear. The impact of HER2 overexpression on survival in pancreatic ductal cancer was examined. Immunohistochemical staining of 129 pancreatic cancers without hematogenous metastases or peritoneal dissemination treated by macroscopically curative resection were analyzed in association with survival data. To determine HER2 overexpression in this pancreatic cancer series, the polyclonal antibody included in HercepTest, which is used worldwide for clinical examination of HER2 overexpression in breast cancer, was used. Immunoreactivity was classified according to the scale presented in the HercepTest Scoring Guidelines. Twenty-two cases (17.1%) had a score of 0, 28 cases (21.7%) had of a score of 1+, 41 cases (31.8%) had a score of 2+, and 38 cases (29.4%) had a score of 3+. Therefore, HER2 overexpression (score 2+ or 3+) was observed in 79 cases (61.2%). Patients with HER2 overexpression tumors had significantly shorter survival times than those with HER2 normal expression (score 0 or 1+) tumors (median survival time, 14.7 vs 20.7 months, respectively; P = 0.0078 on the log-rank test). On multivariate survival analysis, HER2 overexpression remained an independent prognostic factor (hazard ratio, 1.806; P = 0.0258). A significant percentage of pancreatic cancers were demonstrated to have HER2 overexpression, and overexpression of this tyrosine kinase receptor proved to be an independent factor for a worse prognosis. These results should encourage further investigation of treatments using new molecular targeting agents against HER2 protein to improve the survival of pancreatic cancer patients. ( Cancer Sci 2009; 100: 1243–1247) [ABSTRACT FROM AUTHOR]

The National Comprehensive Cancer Network guidelines recommend radiotherapy as a standard treatment for patients with a high risk of recurrence in gastric cancer. Because radiation is harmful to the surrounding organs, a radiation sensitizer might therefore be useful to decrease the side effects of patients with advanced gastric carcinoma. The aim of the current study was to clarify the effect of a DNA methyltransferase inhibitor, 5-aza-2′-deoxycytidine (CdR), on radiation sensitivity in gastric cancer cells. Five gastric cancer cell lines, OCUM-2M, OCUM-12, KATO-III, MKN-45, and MKN-74, were used. The effects of 5-aza-CdR with irradiation on the growth activity, cell-cycle distribution, apoptosis, and apoptosis-associated gene expression were examined. 5-aza-CdR sensitized three of five gastric cancer cell lines to radiation. A combination of irradiation and 5-aza-CdR significantly ( P < 0.05) decreased the growth activity compared with irradiation alone in OCUM-2M, OCUM-12, and MKN-45 cells, but not in KATO-III and MKN-74 cells. The percentage of cells in G2–M phase and the apoptotic rate with irradiation in combination with 5-aza-CdR were increased in OCUM-2M, OCUM-12, and MKN-45 cells compared with irradiation alone, but not in KATO-III and MKN-74 cells. 5-aza-CdR increased the expression of p53, RASSF1, and death-associated protein kinases (DAPK) genes compared with the control or irradiation alone. These findings suggest that 5-aza-CdR might therefore be useful as a radiation sensitizer to treat some types of gastric carcinoma. The arrest at G2–M phase and increased apoptotic rate might be partly mediated by enhanced expression of the p53, RASSF1, or DAPK gene families by 5-aza-CdR. ( Cancer Sci 2009; 100: 181–188) [ABSTRACT FROM AUTHOR]

Epigenetic alterations of DNA methylation play an important role in the regulation of gene expression associated with chemosensitivity of gastric carcinomas. With the aim of improving the chemotherapeutic efficacy of gastric carcinoma, the effect of DNA methyltransferase inhibitor, 5-aza-CdR, on the chemosensitivity of five anticancer drugs was investigated. Human gastric cancer cell lines, OCUM-2M and MKN-74, and five anticancer drugs, 5-FU, PTX, OXA, SN38, and GEM, were used. In both gastric cancer cell lines, a synergistic antiproliferative effect by a combination of 5-aza-CdR at 5 µM was found in SN38 and GEM. 5-Aza-CdR at 5 µM increased apoptosis induced by SN38 and GEM in both cell lines. 5-Aza-CdR increases the expression of DAPK-2 and DAPK-3, RASSF1, and THBS1 genes in both OCUM-2M and MKN-74 cells, but not that of hMLH1, p16, MGMT, E-cadherin, and p53 genes. These findings suggest that 5-aza-CdR is a promising chemotherapeutical agent for gastric carcinomas, in combination with the anticancer drugs SN38 and GEM, in apoptosis signaling. The upregulation of DAPK-2 and DAPK-3, RASSF1, and THBS1 genes by 5-aza-CdR might be associated with the synergistic effect. ( Cancer Sci 2006; 97: 938–944) [ABSTRACT FROM AUTHOR]

We evaluated the effect of a 'tailor-made' chemo-gene therapy in scirrhous gastric cancer (SGC)-bearing nude mice. For this tailor-made approach, we first selected gefitinib (epidermal growth factor receptor-tyrosine kinase inhibitor)-sensitive SGC cell lines, and 5/8 cell lines demonstrated various degrees of gefitinib-sensitivity. In the highly gefitinib-sensitive NUGC-4, the biological response to NK4 (HGF antagonist/angiogenesis inhibitor) was examined. Subsequently, the composition of an NK4-expressing ternary complex (cationic lipid/nucleic acid/HMG-1, 2 protein) was optimized for maximum transfection activity in NUGC-4. Finally, mice were peritoneally coinoculated with NUGC-4 and scirrhous-associated gastric fibroblasts, NF22, on day 0. Animal models were orally administrated gefitinib (50 mg/kg/day, on days 7-28), and peritoneally NK4-expressing ternary complex (on days 14, 21 and 28). NK4-expression suppressed the gefitinib-resistance induced by the interaction between fibroblasts and SGC, and eventually, this tailor-made combination synergistically decelerated the disease progression by inhibiting proliferative, angiogenic and antiapoptotic effects in tumor tissues. On day 28, both the hemoglobin concentration (g/dl) (control ( n = 8), 11.9; treated ( n = 8), 17.3; p = 0.0014) and the numbers of mice in good condition (control, 2; treated, 8; p = 0.0012) were significantly greater, and the abdominal girth (mm) (control, 81.1; treated, 70.3; p = 0.0036) was significantly reduced. The median points of bloody ascite-free survival time (days) (control, 22; treated, 44; p < 0.0001) and time to euthanasia (days) (control, 36.5; treated, 56; p < 0.0001) were also significantly prolonged. This combination is a potentially useful approach to the treatment of peritoneal gefitinib-sensitive SGC dissemination. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The cyclooxygenase (COX)-2 inhibitor has been reported to impede the progression of gastric cancer, but underlying mechanisms remain unclear. We therefore investigated the effect of a COX-2 inhibitor, JTE-522, on the ability of orthotopic fibroblasts to stimulate invasion of scirrhous gastric carcinoma cells. The human scirrhous gastric cancer cell lines OCUM-2D or OCUM-2M, and human gastric fibroblasts (NF-21) were cultured in the absence or presence of JTE-522 at various concentrations. Cancer cells were then assayed for invasiveness in vitro by invasion assay. The effect of prostaglandins (PG) on growth factor production in NF-21 cells was examined by ELISA. Finally, the effects of orally administrated JTE-522 on orthotopically transplanted tumors were examined in nude mice. NF-21 cells stimulated invasion by OCUM-2D cells, an effect suppressed by JTE-522 at 5 × 10−6 M. Hepatocyte growth factor (HGF) and PGE2 production by NF-21 cells were suppressed by JTE-522 ( P < 0.01). PGE2 stimulated HGF production by NF-21 cells in a dose-dependent manner. JTE-522 significantly suppressed orthotopic tumor growth and lymph node metastasis, and also decreased HGF expression by fibroblasts within the gastric tumor. In conclusion, we found that gastric fibroblasts stimulated invasiveness in scirrhous gastric cancer cells, whereas a selective COX-2 inhibitor inhibited this paracrine effect by decreasing fibroblast PGE2 production, resulting in downregulation of HGF production. ( Cancer Sci 2005; 96: 451–455) [ABSTRACT FROM AUTHOR]

We attempted the placement of a self-expandable metallic stent (SEMS) for unresectable malignant obstruction of the proximal colon as well as obstruction of the distal colon and rectum, using a technical device.Thirty patients were selected to place SEMS. The procedure was performed under endoscopic and fluoroscopic guidance. As a technical device, we used an angiographic introducer to straighten the rectosigmoid region. Moreover, we used a transparent hood to easily obtain a front view of the stricture.Of 30 cases of attempted SEMS placement, SEMS was successfully placed in 26 (87%). The technical success rate was 82% (9/11) in strictures of the proximal colon, while it was 89% (17/19) in those of the distal colon or rectum. According to complications, stent migration occurred in one patient (3%) and restenosis was also observed in one patient (3%).Placement of SEMS is a feasible and effective adjunct and alternative to stoma in malignant large bowel obstruction. [ABSTRACT FROM AUTHOR]