Transforming growth factor-beta and hepatocyte growth factor produced by gastric fibroblasts stimulate the invasiveness of scirrhous gastric cancer cells

Ferroptosis regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer

BACKGROUND

Gastric cancer is one of the most common malignant tumors in the world, and its occurrence and development involve complex biological processes. Iron death, as a new cell death mode, has attracted wide attention in recent years. However, the regulatory mechanism of iron death in gastric cancer and its effect on lipid peroxidation metabolism remain unclear.

AIM

To explore the role of iron death in the development of gastric cancer, reveal its relationship with lipid peroxidation, and provide a new theoretical basis for revealing the molecular mechanism of the occurrence and development of gastric cancer.

METHODS

The process of iron death in gastric cancer cells was simulated by cell culture model, and the occurrence of iron death was detected by fluorescence microscopy and flow cytometry. The changes of gene expression related to iron death and lipid peroxidation metabolism were analyzed by high-throughput sequencing technology. In addition, a mouse model of gastric cancer was established, and the role of iron death in vivo was studied by histology and immunohistochemistry, and the level of lipid peroxidation was detected. These methods comprehensively and deeply reveal the regulatory mechanism of iron death on lipid peroxidation metabolism in the occurrence and development of gastric cancer.

RESULTS

Iron death was significantly activated in gastric cancer cells, and at the same time, associated lipid peroxidation levels increased significantly. Through high-throughput sequencing analysis, it was found that iron death regulated the expression of several genes related to lipid metabolism. In vivo experiments demonstrated that increased iron death in gastric cancer mice was accompanied by a significant increase in lipid peroxidation.

CONCLUSION

This study confirmed the important role of iron death in regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer. The activation of iron death significantly increased lipid peroxidation levels, revealing its regulatory mechanism inside the cell.

The Role of cMET in Gastric Cancer—A Review of the Literature

Gastric cancer (GC) is an important cause of cancer worldwide with over one million new cases yearly. The vast majority of cases present in stage IV disease, and it still bears a poor prognosis. However, since 2010, progress has been made with the introduction of targeted therapies against HER2 and with checkpoint inhibitors (PDL1). More agents interfering with other targets (FGFR2B, CLDN18.2) are being investigated. cMET is a less frequent molecular target that has been studied for gastric cancer. It is a proto-oncogene that leads to activation of the MAPK pathway and the PI3K pathway, which is responsible for activating the MTOR pathway. The prevalence of cMET is strongly debated as different techniques are being used to detect MET-driven tumors. Because of the difference in diagnostic assays, selecting patients who benefit from cMET inhibitors is difficult. In this review, we discuss the pathway of cMET, its clinical significance and the different diagnostic assays that are currently used, such as immunohistochemy (IHC), fluorescence in situ hybridization (FISH), the H-score and next-generation sequencing (NGS). Next, we discuss all the current data on cMET inhibitors in gastric cancer. Since the data on cMET inhibitors are very heterogenous, it is difficult to provide a general consensus on the outcome, as inclusion criteria differ between trials. Diagnosing cMET-driven gastric tumors is difficult, and potentially the only accurate determination of cMET overexpression/amplification may be next-generation sequencing (NGS).

Significance of tumor heterogeneity of p-Smad2 and c-Met in HER2-positive gastric carcinoma with lymph node metastasis

Background

Tumor heterogeneity has frequently been observed in gastric cancer (GC), but the correlation between patients’ clinico-pathologic features and the tumoral heterogeneity of GC-associated molecules is unclear. We investigated the correlation between lymph node metastasis and the intra-tumoral heterogeneity of driver molecules in GC.

Materials and methods

We retrospectively analyzed the cases of 504 patients who underwent a gastrectomy at the Department of Gastroenterological Surgery, Osaka Metropolitan University and 389 cases drawn from The Cancer Genome Atlas (TCGA) data. We performed a clustering analysis based on eight cancer-associated molecules including HER2, c-Met, and p-Smad2 using the protein expression revealed by our immunohistochemical study of the patients’ and TCGA cases. We determined the correlations between HER2 expression and the other molecules based on the degree of lymph node metastasis.

Results

Immunohistochemical staining data showed that a 43 of the 504 patients with GC (8.5%) were HER2-positive. In the HER2-positive cases, the expressions of c-Met and p-Smad2 were increased in accord with the lymph-node metastatic level. The overall survival of the HER2-positive GC patients with both p-Smad2 and c-Met expression was significantly (p = 0.030) poorer than that of the patients with p-Smad2-negative and/or c-Met-negative expression. The results of the TCGA data analysis revealed that 58 of the 389 GC cases (14.9%) were ERBB2-positive. MET expression was more frequent in the N1 metastasis group than the N0 group. In the high lymph-node metastasis (N2 and N3) group, SMAD2 expression was more frequent, as was ERBB2 and MET expression.

Conclusion

p-Smad2 and c-Met signaling might play important roles in lymph node metastasis in HER2-positive GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09681-3.

The role of transforming growth factor β in upper gastrointestinal cancers: A systematic review

Esophageal and gastric malignancies are associated with poor prognosis, in part due to development of recurrences or metastases after curative treatment. The transforming growth factor β (TGF-β) pathway might play a role in the development of treatment resistance. In this systematic review, we provide an overview of preclinical studies investigating the role of TGF-β in esophageal and gastric malignancies. We systematically searched MEDLINE/PubMed and EMBASE for eligible preclinical studies describing the effect of TGF-β or TGF-β inhibition on hallmarks of cancer, such as proliferation, migration, invasion, angiogenesis and immune evasion. In total, 2107 records were screened and 45 articles were included, using mouse models and 45 different cell lines. TGF-β failed to induce apoptosis in twelve of sixteen tested cell lines. TGF-β could either decrease (five cell lines) or increase proliferation (seven cell lines) in gastric cancer cells, but had no effect in esophageal cancer cells. In all esophageal and all but two gastric cancer cell lines, TGF-β increased migratory, adhesive and invasive capacities. In vivo studies showed increased metastasis in response to TGF-β treatment. Additionally, TGF-β was shown to induce vascular endothelial growth factor production and differentiation of cancer-associated fibroblasts and regulatory T-cells. In conclusion, we found that TGF-β enhances hallmarks of cancer in most gastric and esophageal cancer cell lines, but not in all. Therefore, targeting the TGF-β pathway could be an attractive strategy in patients with gastric or esophageal cancer, but additional clinical trials are needed to define patient groups who would benefit most.

Potential mechanisms of tumor progression associated with postoperative infectious complications

There is increasing evidence that postoperative infectious complications (PICs) are associated with poor prognosis after potentially curative surgery. However, the role that PICs play in tumor development remains unclear. In this article, we reviewed the literature for novel insights on the mechanisms of cancer progression associated with PICs. The Medline and EMBASE databases were searched for publications regarding the role of suppression of antitumor immunity by PIC in tumor progression and selected 916 manuscripts were selected for this review. In addition, a summary of the authors' own experimental data from this field was set in the context of current knowledge regarding cancer progression under septic conditions. Initially, sepsis/microbial infection dramatically activates the systemic immune system with increases in pro-inflammatory mediators, which results in the development of systemic inflammatory response syndrome; however, when sepsis persists in septic patients, a shift toward an anti-inflammatory immunosuppressive state, characterized by macrophage deactivation, reduced antigen presentation, T cell anergy, and a shift in the T helper cell pattern to a predominantly TH2-type response, occurs. Thus, various cytokine reactions and the immune status dynamically change during microbial infection, including PIC. We proposed three possible mechanisms for the tumor progression associated with PIC: first, a mechanism in which microbes and/or microbial PAMPs may be directly involved in cancer growth; second, a mechanism in which factors released from immunocompetent cells during infections may affect tumor progression; and third, a mechanism in which factors suppress host tumor immunity during infections, which may result in tumor progression. A more detailed understanding by surgeons of the immunological features in cancer patients with PIC can subsequently open new avenues for improving unfavorable long-term oncological outcomes associated with PICs.

Crosstalk Between Cancer Associated Fibroblasts and Cancer Cells in Scirrhous Type Gastric Cancer

Gastric cancer (GC) is the third leading cause among all cancer deaths globally. Although the treatment outcome of GC has improved, the survival of patients with GC at stages III and IV remains unsatisfactory. Among several types of GC, scirrhous type GC (SGC) shows highly aggressive growth and invasive activity, leading to frequent peritoneal metastasis. SGC is well known to accompany abundant stromal cells that compose the tumor microenvironment (TME) along with the produced extracellular matrix (ECM) and secreted factors. One of the main stromal components is cancer associated fibroblast (CAF). In the SGC microenvironment, CAFs are a source of various secreted factors, including fibroblast growth factors (FGFs), which mediate prominent tumor-stimulating activity. In turn, cancer cells also secrete numerous factors, which can activate and educate CAFs. Current findings suggest that cancer cells and stromal cells communicate interactively via the soluble factors, the ECM, and likely also by exosomes. In this review, we focus on the soluble factors mediating communication between cancer cells and CAFs in SGC, and consider how they are related to the modulation of TME and the high rate of peritoneal metastasis. At last, we discuss the perspectives on targeting these communication pathways for improved future treatment.

Exosomal miRNA-34 from cancer-associated fibroblasts inhibits growth and invasion of gastric cancer cells in vitro and in vivo

Gastric cancer (GC) is one of the most common malignancies worldwide manifesting high morbidity and mortality. Cancer-associated fibroblasts (CAFs), important components of the tumor microenvironment, are essential for tumorigenesis and progression. Exosomes secreted from CAFs have been reported as the critical molecule-vehicle in intercellular crosstalk. However, the precise mechanism underlying the effect of CAFs remains to be fully investigated. In this study, we aimed to determine the role of CAFs and their exosomes in the progression of GC and related mechanisms. The results revealed that miRNA-34 was downregulated in both GC fibroblasts (GCFs) and GC cell lines while the overexpression of miRNA-34 suppressed the proliferation, invasion, and motility of GC cell lines. Coculturing GC cells with miRNA-34-overexpressing GCFs led to the suppression of cancer progression. Also, exosomes derived from GCFs were taken up by GC cells in vitro and in vivo and exerted antitumor roles in GC. In addition, exosomal miRNA-34 inhibited GC cell proliferation and invasion in vitro and suppressed tumor growth in vivo. Furthermore, 16 genes were identified as potential downstream targeting genes of miRNA-34. Taken together, GCFs-derived exosomal miRNA-34 may be a promising targeting molecule for therapeutic strategies in GC.

Low-dose eribulin mesylate exerts antitumor effects in gastric cancer by inhibiting fibrosis via the suppression of epithelial-mesenchymal transition and acts synergistically with 5-fluorouracil

Background

Characterized by aggressive proliferation, extensive stromal fibrosis, and resulting drug resistance, peritoneal dissemination in gastric cancer remains associated with poor prognosis. Interaction between cancer and stromal cells accelerates tumor progression via epithelial–mesenchymal transition (EMT), which is one of the major causes of tissue fibrosis, and human peritoneal mesothelial cells (HPMCs) play important roles as cancer stroma in peritoneal dissemination. Transforming growth factor-β (TGF-β) has a pivotal function in the progression of EMT, and Smad proteins play an important role in the TGF-β signaling pathway. Eribulin mesylate (eribulin), a nontaxane microtubule dynamics inhibitor used for the treatment of advanced breast cancer, inhibits EMT changes in triple-negative breast cancer cells. We examined its ability to inhibit tumor progression and EMT changes resulting from the interaction between gastric cancer cells and HPMCs and to act synergistically with 5-fluorouracil (5-FU), a key drug for gastric cancer.

Materials and methods

Proliferation of gastric cancer cells and HPMCs isolated from healthy omentum was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Following gastric cancer cell/HPMC coculture, EMT markers were detected by immunofluorescence, immunohistochemistry, and Western blotting; invasion assays were performed; and TGF-β and Smad phosphorylation were assessed by Western blotting and enzyme-linked immunosorbent assay. A mouse fibrotic tumor xenograft model was established using gastric cancer cell/HPMC cocultures. The effect of eribulin and/or 5-FU was tested in each case.

Results

Eribulin significantly suppressed gastric cancer cell proliferation and EMT changes in MKN-45 gastric cancer cells and HPMCs induced by their interaction in vitro. Eribulin inhibited EMT at much lower concentrations (≥0.5 nM for MKN-45 and ≥0.1 nM for HPMCs) than its half maximal inhibitory concentrations (2.2 nM for MKN-45 and 8.1 nM for HPMCs), and this resulted, at least partly, from the downregulation of TGF-β/Smad signaling. Eribulin administration of ≥0.1 mg/kg suppressed tumor progression (0.1 mg/kg, p=0.02), and fibrosis was inhibited by lower dose (0.05 mg/kg, p=0.008) in the xenograft model. Furthermore, 0.05 mg/kg administration with 5-FU brought about synergistic antitumor effects (p=0.006).

Conclusion

Low-dose eribulin combined with 5-FU might be a promising therapy for peritoneal dissemination in gastric cancer.

The significance of a nineteenth century definition in the era of genomics: linitis plastica

Background

Linitis plastica due to gastric adenocarcinoma is a condition with a long history, but still lacks a standardized definition and is commonly confused with Borrmann type IV, Lauren diffuse, and signet-cell type gastric cancer. The absence of a clear definition is a problem when investigating its biological characteristics and role as a possible independent factor for prognosis. Nevertheless, the biological behavior for linitis plastica, which is unique, may be valuable in risk stratification and have implications for treatment. A definition of linitis plastica based on molecular or genomic criteria could represent a useful starting point for investigating new targeted therapies.

Main body

This literature review of linitis plastica will focus on the current classifications for gastric cancer, illustrating how the concept of linitis plastica relates to them in most cases and identifying a clear and reproducible definition. Moreover, the review will highlight the diagnostic challenges associated with linitis plastica, its prognostic implications, and the therapeutic options available. Future perspectives for its management are also addressed.

Conclusion

Linitis plastica is a carcinoma with a scirrhous stroma, involving the submucosal and muscular layers of the stomach even in the absence of mucosal alteration. In most cases, the primary cancer cells are signet-ring cells or scattered cells in the context of a poorly differentiated carcinoma. Diagnosis is challenging. Staging should be thorough, including diagnostic laparoscopy in all cases due to the high incidence of peritoneal involvement. The prognostic significance of linitis plastica is still controversial. Curative-intent surgery, when feasible, should be performed, with a multimodality treatment approach. Cancer-stroma interactions are important features of this disease, and represent attaining potential target for future therapies. Future pathologic assessments of gastric cancer should report the stromal reaction in order to allow better characterization of the tumor.

Cytokine networks and their association with Helicobacter pylori infection in gastric carcinoma

Cytokine networks as dynamic networks are pivotal aspects of tumor immunology, especially in gastric cancer (GC), in which infection, inflammation, and antitumor immunity are key elements of disease progression. In this review, we describe functional roles of well-known GC-modulatory cytokines, highlight the functions of cytokines with more recently described roles in GC, and emphasize the therapeutic potential of targeting the complex cytokine milieu. We also focus on the role of Helicobacter pylori (HP)-induced inflammation in GC and discuss how HP-induced chronic inflammation can lead to the induction of stem cell hyperplasia, morphological changes in gastric mucosa and GC development.

Diffuse-type gastric cancer cells switch their driver pathways from FGFR2 signaling to SDF1/CXCR4 axis in hypoxic tumor microenvironments

Cancer-associated fibroblasts (CAFs) have been considered to play an important role for tumor progression of cancer. Solid tumors contain heterogeneous distribution of oxygen in their microenvironments. This study investigated the growth signaling of gastric cancer (GC) cells in focus on the interaction with CAFs and GC cells under normoxia and hypoxia. Four diffuse-type GC cell lines, two intestinal-type GC cell lines and three CAF cell lines were used. Cells were examined for expression of C-X-C chemokine receptor 4 (CXCR4), fibroblast growth factor receptor 2 (FGFR2) and stromal-derived factor 1 (SDF1) by RT-PCR, western blot, ELISA and immunohistochemical staining of xenografted tumors. GC cell proliferation was examined under hypoxia in the presence or absence of CAFs, a FGFR2 inhibitor, a CXCR4 inhibitor and HIF1α siRNA. Proliferation of diffuse-type GC cells, but not intestinal-type GC cells, was significantly increased by CAFs. CXCR4 expression by diffuse-type GC cells was significantly increased in hypoxia, while FGFR2 expression was decreased. CXCR4 expression was correlated with hypoxic microenvironment of xenografted tumor, but FGFR2 expression was not. FGFR2 inhibition significantly decreased the growth-stimulating activity of CAFs for diffuse-type GC cells in normoxia. In contrast, CXCR4 inhibition significantly decreased the growth-stimulating activity of CAFs in hypoxia. SDF1 production by CAFs was increased in hypoxia, while cancer cells did not produce SDF1. HIF1 siRNA significantly decreased both CXCR4 expression by diffuse-type GC cells and SDF1 production by CAFs. These findings suggest that diffuse-type GC cells might switch their driver pathways from FGFR2 signaling to SDF1/CXCR4 axis through HIF1 in hypoxic tumor microenvironments.

Bone marrow-derived stromal cells are associated with gastric cancer progression

Background:

The aim of this study was to clarify the role of bone marrow-derived stromal cells (BM-SCs) expressing CD271 in the development of gastric cancer.

Methods:

The effect of human BM-SCs on the proliferation and motility of six gastric cancer cell lines, OCUM-2M, OCUM-2MD3, OCUM-12, KATO-III, NUGC-3, and MKN-74, was examined. CD271 expression levels in BM-SCs were analysed by flow cytometry. We also generated a gastric tumour model by orthotopic inoculation of OCUM-2MLN cells in mice that had received transplantation of bone marrow from the CAG-EGFP mice. The correlation between the clinicopathological features of 279 primary gastric carcinomas and CD271 expression in tumour stroma was examined by immunohistochemistry.

Results:

Numerous BM-SCs infiltrated the gastric tumour microenvironment; CD271 expression was found in ∼25% of BM-SCs. Conditioned medium from BM-SCs significantly increased the proliferation of gastric cancer cell lines. Furthermore, conditioned medium from gastric cancer cells significantly increased the number of BM-SCs, whereas migration of OCUM-12 and NUGC-3 cells was significantly increased by conditioned medium from BM-SCs. CD271 expression in stromal cells was significantly associated with macroscopic type-4 cancers, diffuse-type tumours, and tumour invasion depth. The overall survival of patients (n=279) with CD271-positive stromal cells was significantly worse compared with that of patients with CD271-negative stromal cells. This is the first report of the significance of BM-SCs in gastric cancer progression.

Conclusions:

Bone marrow-derived stromal cells might have an important role in gastric cancer progression, and CD271-positive BM-SCs might be a useful prognostic factor for gastric cancer patients.

Impact of S-1 plus Cisplatin Neoadjuvant Chemotherapy on Scirrhous Gastric Cancer

OBJECTIVE

This retrospective study aimed to address the therapeutic outcome for scirrhous gastric cancer patients by evaluating the effect of neoadjuvant chemotherapy prior to gastrectomy.

METHODS

Two cycles of a 3-week regimen of fluoropyrimidine S-1 (40 mg/m(2), orally, twice daily), together with cisplatin (60 mg/m(2), intravenously, day 8), were administered to patients, separated by a 2-week rest period. Surgery was performed 3 weeks later in the neoadjuvant group (n = 27). We retrospectively evaluated overall survival and prognostic factors in these patients.

RESULTS

Univariate analysis showed that positive lavage cytology indicated significantly worse prognoses. In the 15 patients who also underwent curative gastrectomies after S-1 plus cisplatin chemotherapy, the pathological response grade was a significant prognostic factor for 5-year survival. Additionally, lymph node metastasis tended to be an adverse prognostic factor.

CONCLUSION

After S-1 plus cisplatin neoadjuvant chemotherapy, a grade 2-3 pathological response may predict favorable outcomes in scirrhous gastric cancer patients receiving curative gastrectomy, but further studies are needed to confirm these results.

MicroRNA-106b in cancer-associated fibroblasts from gastric cancer promotes cell migration and invasion by targeting PTEN

It is well established that the interaction between cancer cells and microenvironment has a critical role in tumor development, but the roles of miRNAs in this interaction are rarely known. Here, we have shown that miR-106b is up-regulated in cancer associated fibroblasts compared with normal fibroblasts established from patients with gastric cancer, the expression level of miR-106b is associated with poor prognosis of patients, and CAFs with down-regulated miR-106b could significantly inhibit gastric cancer cell migration and invasion by targeting PTEN. Taken together, these data suggest that miR-106b might be a novel candidate target for the treatment of gastric cancer.

A c-Met inhibitor increases the chemosensitivity of cancer stem cells to the irinotecan in gastric carcinoma

Background:

Cancer stem cells (CSCs) may be postulated mediators of the chemoresistance. This study aimed to determine an effective signal inhibitor with effects on the proliferation of CSCs in combination with anticancer drugs.

Methods:

We used three gastric cancer cell lines and three side population (SP)-enriched CSC cell lines. We examined the combined effects of inhibitors against stemness signals, including c-Met inhibitor SU11274, and five anticancer drugs on the CSC proliferation and mRNA expression of chemoresistance-associated genes.

Results:

The IC₅₀ of irinotecan in SP-enriched CSC was 10.5 times higher than parent OCUM-2M cells, whereas that of oxaliplatin, taxol, gemcitabine, and 5-fluorouracil was 2.0, 2.8, 2.0, and 1.2, respectively. The SP cell lines had higher expression levels of UGT1A1, ABCG2, and ABCB1 than their parent cell lines. There was a synergistic antiproliferative effect with a combination of SU11274 and SN38 in SP cells, but not other inhibitors. The SU11274 significantly decreased the expression of UGT1A1, but not ABCG2 and ABCB1. The SN38 plus SU11274 group more effectively suppressed in vivo tumour growth by OCUM-2M/SP cells than either group alone.

Conclusion:

Cancer stem cells have chemoresistance to irinotecan. The c-Met inhibitor may be a promising target molecule for irinotecan-based chemotherapy of gastric cancer.

Low-dose paclitaxel modulates tumour fibrosis in gastric cancer

Various treatments have been used for peritoneal dissemination, which is the most common mode of metastasis in gastric cancer, but sufficiently good clinical outcomes have not yet been obtained because of the presence of rich fibrous components and acquired drug resistance. Epithelialmesenchymal transition (EMT) is one of the major causes of tissue fibrosis and transforming growth factor-β (TGF-β) has a pivotal function in the progression of EMT. Smad proteins play an important role in the TGF-β signalling pathway. The TGF-β/Smad signalling pathway can be modulated by stabilising microtubules with paclitaxel (PTX). Here, we investigated whether paclitaxel can modulate TGF-β/Smad signalling in human peritoneal methothelial cells (HPMCs). To determine the cytostatic concentrations of antineoplastic agents in HPMCs, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed using PTX, 5-fluorouracil and cisplatin. The minimum concentration that caused significant inhibition of TGF-β1-induced morphological changes in human peritoneal methothelial cells on pre-treatment with PTX was 5 nM at 48 h (cell viability: 87.1±1.5%, P<0.01). The TGF-β signalling cascade and the status of various fibrous components were evaluated by immunofluorescence staining, real-time quantitative PCR and western blotting. TGF-β signalling induced morphological changes, α-SMA expression and collagen I synthesis in HPMCs and PTX treatment suppressed these EMT-like changes. Moreover, PTX treatment markedly suppressed Smad2 phosphorylation. These data suggest that at a low-dose, PTX can significantly suppress the TGF-β/Smad signalling pathway by inhibiting Smad2 phosphorylation in the human peritoneum and that this can reduce stromal fibrosis.

Cancer-associated orthotopic myofibroblasts stimulates the motility of gastric carcinoma cells

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-2MD3, OCUM-12, MKN-45) and four human gastric fibroblast cell lines (cancer-associated orthotopic fibroblast [CaF]-29, CaF-33, normal orthotopic fibroblast [NF]-29, NF-33) were used. The cancer-associated orthotopic fibroblast cell lines CaF-29 and CaF-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 CaF-29 (33%) and CaF-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 (CaF-29 and CaF-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 siRNA 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.

Clinical correlations and prognostic relevance of tissue angiogenic factors in patients with gastric cancer

AIMS

To evaluate the relationship between vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) levels in gastric cancer tissue and clinicopathological features and to determine whether these factors were correlated with survival.

MATERIALS AND METHODS

We analysed tissue samples from 58 patients with gastric cancer and used 24 normal gastric mucosae as controls. Tissue levels of VEGF and HGF were measured in tissue extracts by enzyme-linked immunosorbent assay.

RESULTS

HGF and VEGF levels were significantly higher in gastric cancer tissue than in matched normal gastric mucosa. VEGF levels were significantly increased in cancer tissue from cases involving lymphatic invasion. HGF levels were significantly increased according to the disease stage. Patients with high levels of VEGF or HGF showed significantly worse survival rates than patients with low levels. Using multivariate analysis, a high level of VEGF or HGF was an independent factor predicting poor survival.

CONCLUSIONS

Intratumoral levels of HGF and VEGF are an important prognostic determinant in gastric cancer. The current findings suggest that high concentrations of HGF and VEGF may induce aggressive tumour growth and metastasis.

Co-expression of hepatocyte growth factor and c-Met predicts peritoneal dissemination established by autocrine hepatocyte growth factor/c-Met signaling in gastric cancer

Epithelial-mesenchymal transition (EMT) promotes and facilitates migration and invasion of epithelial tumor cells. EMT is induced by factors such as hepatocyte growth factor (HGF). This study aimed to establish whether the HGF/c-Met pathway is associated with gastric cancer metastasis; especially peritoneal dissemination. HGF and c-Met expression and EMT-related molecules were evaluated using real-time PCR and immunohistochemistry. The role of the HGF/c-Met pathway in EMT and anoikis was determined, and kinase inhibitor SU11274 was tested for its ability to block HGF-induced biological effects. In HGF(-) /c-Met(+) gastric cancer cells, recombinant HGF promoted an EMT phenotype that was characterized by morphology, impaired E-cadherin and induction of vimentin. HGF promoted cell growth, invasiveness and migration and inhibition of anoikis. SU11274 blocked HGF-induced EMT and biological effects in vitro. In HGF(+) /c-Met(+) gastric cancer cells, HGF did not affect the biological outcome of EMT and anoikis, but SU11274 exerted the same inhibitory effects as in HGF(-) /c-Met(+) cells. In vivo, HGF(+) /c-Met(+) gastric cancer cells only established peritoneal dissemination and SU11274 inhibited tumor growth. Clinically, HGF expression was significantly correlated with c-Met expression in gastric cancer. Increased HGF and c-Met had a significant association with poor prognosis and predicted peritoneal dissemination. We demonstrated that the HGF/c-Met pathway induces EMT and inhibition of anoikis in gastric cancer cells. Co-expression of HGF and c-Met has the potential to promote peritoneal dissemination in gastric cancer. Blockade of the autocrine HGF/c-Met pathway could be clinically useful for the treatment of peritoneal dissemination in gastric cancer.

Upregulation of cancer-associated myofibroblasts by TGF-β from scirrhous gastric carcinoma cells

BACKGROUND

Myofibroblasts in the cancer microenvironment have recently been implicated in tumour growth and metastasis of gastric cancer. However, the mechanisms responsible for the regulation of myofibroblasts in cancer-associated fibroblasts (CAFs) remain unclear. This study was performed to clarify the mechanisms for regulation of myofibroblasts in gastric cancer microenvironment.

METHODS

Two CAFs (CaF-29 and CaF-33) from the tumoural gastric wall and a normal fibroblast (NF-29) from the nontumoural gastric wall, 4 human gastric cancer cell lines from scirrhous gastric cancer (OCUM-2MD3 and OCUM-12), and non-scirrhous gastric cancer (MKN-45 and MKN-74) were used. Immunofluorescence microscopy by triple-immunofluorescence labelling (α-SMA, vimentin, and DAPI) was performed to determine the presence of α-SMA-positive myofibroblasts. Real-time RT-PCR was performed to examine α-SMA mRNA expression.

RESULTS

Immunofluorescence microscopy showed that the frequency of myofibroblasts in CaF-29 was greater than that in NF-29. The number of myofibroblasts in gastric fibroblasts gradually decreased with serial passages. Transforming growth factor-β (TGF-β) significantly increased the α-SMA expression level of CAFs. Conditioned medium from OCUM-2MD3 or OCUM-12 cells upregulated the α-SMA expression level of CAFs, but that from MKN-45 or MKN-74 cells did not. The α-SMA upregulation effect of conditioned medium from OCUM-2MD3 or OCUM-12 cells was significantly decreased by an anti-TGF-β antibody or Smad2 siRNA.

CONCLUSION

Transforming growth factor-β from scirrhous gastric carcinoma cells upregulates the number of myofibroblasts in CAFs.

Borrmann's macroscopic criteria and p-Smad2 expression are useful predictive prognostic markers for cytology-positive gastric cancer patients without overt peritoneal metastasis

BACKGROUND

All patients with peritoneal-free cancer cells (CY1) do not always develop a peritoneal recurrence (P1). The goal of this study was to identify characteristic features of peritoneal-free cancer cells that could develop into peritoneal recurrence.

METHODS

Of 1,474 patients, 91 were identified with CY1P0, and the remaining 1,383 with CY0P0. Immunohistochemical staining with anti-phosphorylated Smad 2 (p-Smad2) was performed on paraffin-embedded specimens from the 91 CY1P0 patients.

RESULTS

CY1 was significantly correlated with Borrmann's type-4 cancer, clinical T stage, and lymph node metastasis. CY1P0 patients with Borrmann's type-4 cancer more frequently develop peritoneal recurrence than do those with other types of tumors. The 5-year survival rate of patients with Borrmann's type-4 tumors was significantly (p = 0.023) low (6.3%) compared with that of patients with other types of tumors (27.7%). The prognosis for p-Smad2-positive patients was significantly poorer than that of p-Smad2-negative patients. In CY1 and/or P1 patients with Borrmann's type-4 tumors, no significant difference in prognosis was identified between those who had surgery and those who did not.

CONCLUSIONS

Activated Smad signaling might be associated with a high potential for peritoneal recurrence in CY1P0 patients. Borrmann's macroscopic criteria and p-Smad2 expression are useful markers for surgeons selecting advanced gastric cancer patients with CY1P0 for gastrectomy.

Transforming growth factor-β decreases the cancer-initiating cell population within diffuse-type gastric carcinoma cells

Stem cells in normal tissues and cancer-initiating cells (CICs) are known to be enriched in side population (SP) cells. However, the factors responsible for the regulation of expression of ABCG2, involved in efflux of dyes, in SP cells have not been fully investigated. Here, we characterized the SP cells within diffuse-type gastric carcinoma, and examined the effects of transforming growth factor-β (TGF-β) on SP cells. Diffuse-type gastric carcinoma cells established from four independent patients universally contained SP cells between 1 and 4% of total cells, which displayed greater tumorigenicity than non-SP cells did. TGF-β repressed the transcription of ABCG2 through direct binding of Smad2/3 to its promoter/enhancer, and the number of SP cells and the tumor-forming ability of cancer cells were decreased by TGF-β, although ABCG2 is not directly involved in the tumor-forming ability of SP cells. Cancer cells from metastatic site expressed much higher levels of ABCG2 and included a greater percentage of SP cells than parental cancer cells did. SP cells are thus responsible for the progression of diffuse-type gastric carcinoma, and TGF-β negatively contributes to maintain the CICs within the cancer.

Roles of inflammatory cytokines in the progression of gastric cancer: friends or foes?

Increasing evidence is being reported regarding the hypothesis that several proinflammatory and anti-inflammatory cytokines may promote tumor progression and affect the host antitumor response. However, the manner in which a local cytokine network operates in tumor development remains unclear. We reviewed the literature to examine the consequences of novel insights into inflammatory cytokines associated with gastric cancer progression. The Medline and EMBASE databases were searched for publications regarding the role of inflammatory cytokines in the development of gastric cancer. A number of studies have suggested that several proinflammatory and anti-inflammatory cytokines promote tumor progression through the direct activation of nuclear factor-κB (NF-κB) and the upregulation of angiogenesis and adhesion molecules. Furthermore, these processes suppress host antitumor immunity, leading to tumor progression and metastasis. In patients with advanced gastric cancer, most cytokines that enhance or suppress host antitumor immunity appear to have elevated serum and local expression levels. The net cytokine environment fluctuates at various stages of tumor development. In conclusion, a more detailed understanding of the differential roles of malignant cell-derived and hostderived cytokines at different stages of the malignant process could, consequently, open new avenues for the manipulation of cytokine expression and function in cancer immunotherapy for gastric cancer.

Effects of valproic acid on the cell cycle and apoptosis through acetylation of histone and tubulin in a scirrhous gastric cancer cell line

BACKGROUND

Management of peritoneal dissemination is the most critical problem in gastric cancer. This study was performed to investigate the inhibitory effects of valproic acid (VPA) on a highly peritoneal-seeding cell line of human scirrhous gastric cancer, OCUM-2MD3, and to explore the mechanism and the potential of VPA.

METHODS

The effects of VPA on the growth of OCUM-2MD3 cells were assessed by MTT assay. In addition, paclitaxel (PTX) was combined with VPA to evaluate their synergistic effects. HDAC1 and HDAC2 expression were evaluated by western blotting in OCUM-2MD3 cells and other gastric cancer cell lines (TMK-1, MKN-28). The acetylation status of histone H3 and α-tubulin after exposure to VPA were analyzed by western blotting. The activities of cell cycle regulatory proteins and apoptosis-modulating proteins were also examined by western blotting. The effects of VPA in vivo were evaluated in a xenograft model, and apoptotic activity was assessed by TUNEL assay.

RESULTS

OCUM-2MD3 cells showed high levels of HDAC1 and HDAC2 expression compared with TMK-1 and MKN-28. The concentration of VPA required for significant inhibition of cell viability (P < 0.05) was 5 mM at 24 h and 0.5 mM at 48 h and 72 h. The inhibition of VPA with PTX showed dose-dependent and combinatorial effects. VPA increased acetyl-histone H3, acetyl-α-tubulin, and p21WAF1 levels accompanied by upregulation of p27, caspase 3, and caspase 9, and downregulation of bcl-2, cyclin D1, and survivin. In the xenograft model experiment, the mean tumor volume of the VPA-treated group was significantly reduced by 36.4%, compared with that of the control group at 4 weeks after treatment (P < 0.01). The apoptotic index was significantly higher in the VPA-treated group (42.3% ± 3.5%) than in the control group (7.7% ± 2.5%) (P < 0.001).

CONCLUSIONS

VPA induced dynamic modulation of histone H3 and α-tubulin acetylation in relation with the anticancer effect and the enhancement of PTX in the OCUM-2MD3 cell line. Therefore, VPA in combination with PTX is expected to be a promising therapy for peritoneal dissemination of scirrhous gastric cancer.

Roles of inflammatory cytokines in the progression of gastric cancer: friends or foes?

Increasing evidence is being reported regarding the hypothesis that several proinflammatory and anti-inflammatory cytokines may promote tumor progression and affect the host antitumor response. However, the manner in which a local cytokine network operates in tumor development remains unclear. We reviewed the literature to examine the consequences of novel insights into inflammatory cytokines associated with gastric cancer progression. The Medline and EMBASE databases were searched for publications regarding the role of inflammatory cytokines in the development of gastric cancer. A number of studies have suggested that several proinflammatory and anti-inflammatory cytokines promote tumor progression through the direct activation of nuclear factor-κB (NF-κB) and the upregulation of angiogenesis and adhesion molecules. Furthermore, these processes suppress host antitumor immunity, leading to tumor progression and metastasis. In patients with advanced gastric cancer, most cytokines that enhance or suppress host antitumor immunity appear to have elevated serum and local expression levels. The net cytokine environment fluctuates at various stages of tumor development. In conclusion, a more detailed understanding of the differential roles of malignant cell-derived and hostderived cytokines at different stages of the malignant process could, consequently, open new avenues for the manipulation of cytokine expression and function in cancer immunotherapy for gastric cancer.

Combination effect of a TGF-beta receptor kinase inhibitor with 5-FU analog S1 on lymph node metastasis of scirrhous gastric cancer in mice

Transforming growth factor-beta (TGF-beta) signals are closely associated with the distant metastases of gastric cancer. The aim of this study was to clarify the effect of a TGF-beta receptor I (TbetaR-I) phosphorylation inhibitor, Ki26894, in combination with anticancer drugs, on the lymph node (LN) metastasis of scirrhous gastric cancer. A novel TbetaR-I kinase inhibitor, Ki26894, inhibits the phosphorylation of Smad2 at the ATP binding site of TbetaR-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 TbetaR-I kinase inhibitor with S1 is useful for the treatment of scirrhous gastric carcinoma with LN metastasis. (Cancer Sci 2010).

Myofibroblasts are associated with the progression of scirrhous gastric carcinoma

Fibroblasts, particularly myofibroblasts, affect the malignant progression of cancer cells in vitro. However, to date few reports have addressed the clinical significance of myofibroblasts in the gastric cancer microenvironment. This study examined the correlation between myofibroblast expression and clinicopathological features in gastric carcinoma. A total of 265 primary gastric tumors resected by gastrectomy were stained with antibodies against α-smooth muscle actin and vimentin. Stromal cells positive for vimentin were considered to be fibroblasts. Myofibroblasts were defined as fibroblasts positive for α-smooth muscle staining. Myofibroblast-positive gastric carcinoma was established when myofibroblasts accounted for more than 25% of fibroblasts in the cancer stroma. Myofibroblast expression was positive in 92 (35%) of the 265 gastric carcinomas. Myofibroblast expression showed a significantly (p<0.001) high frequency in advanced gastric cancers (76 of 146), in comparison to the early stage cancers (16 of 119). Taken together, there was a statistically significant correlation between myofibroblast expression and scirrhous type gastric cancer (p<0.001), lymph node metastasis (p<0.001), lymphatic invasion (p<0.001) and peritoneal dissemination (p=0.005). The prognosis of patients with tumors positive for myofibroblast expression was significantly (p<0.001) worse, while a multivariate analysis revealed that myofibroblast expression was not an independent prognostic factor. These findings suggest that myofibroblasts are associated with scirrhous gastric cancer. Overexpression of myofibroblasts may therefore be a useful prognostic indicator of gastric carcinoma.

Inhibitory effect of a TGFbeta receptor type-I inhibitor, Ki26894, on invasiveness of scirrhous gastric cancer cells

Background:

Gastric cancer cells frequently metastasise, partly because of their highly invasive nature. Transforming growth factor-β (TGF-β) receptor signalling is closely associated with the invasion of cancer cells. The aim of this study was to clarify the effect of a TGF-β receptor (TβR) phosphorylation inhibitor on the invasiveness of gastric cancer cells.

Methods:

Four gastric cancer cell lines, including two scirrhous-type cell lines and two non-scirrhous-type cell lines, were used. A TβR type I (TβR-I) kinase inhibitor, Ki26894, inhibits the phosphorylation of Smad2 at an ATP-binding site of TβR-I. We investigated the expression levels of TβR and phospho-Smad2, and the effects of TGF-β in the presence or absence of Ki26894 on Smad2 phosphorylation, invasion, migration, epithelial-to-mesenchymal transition (EMT), Ras homologue gene family member A (RhoA), ZO-2, myosin, and E-cadherin expression of gastric cancer cells.

Results:

TβR-I, TβR-II, and phospho-Smad2 expressions were found in scirrhous gastric cancer cells, but not in non-scirrhous gastric cancer cells. Ki26894 decreased Smad2 phosphorylation induced by TGF-β1 in scirrhous gastric cancer cells. Transforming growth factor-β1 upregulated the invasion, migration, and EMT ability of scirrhous gastric cancer cells. Transforming growth factor-β1 significantly upregulated the activity of RhoA and myosin phosphorylation, whereas TGF-β1 decreased ZO-2 and E-cadherin expression in scirrhous gastric cancer cells. Interestingly, Ki26894 inhibited these characteristics in scirrhous gastric cancer cells. In contrast, non-scirrhous gastric cancer cells were not affected by TGF-β1 or Ki26894 treatment.

Conclusion:

A TβR-I kinase inhibitor decreases the invasiveness and EMT of scirrhous gastric cancer cells. Ki26894 is therefore considered to be a promising therapeutic compound for the metastasis of scirrhous gastric carcinoma.

Cancer-stromal interactions in scirrhous gastric carcinoma

Fibroblasts play an important role in the progression, growth and spread of gastric cancers. Cancer-stroma interactions have been especially evident in the scirrhous type of gastric carcinoma. Fibroblasts are associated with the cancer progression at the primary and metastatic site. The proliferative and invasive ability of scirrhous gastric cancer cells are closely associated with the growth factors produced by organ-specific fibroblasts. Fibroblasts are therefore a key determinant in the malignant progression of gastric cancer and represent an important target for cancer therapies.

A novel transforming growth factor beta receptor kinase inhibitor, A-77, prevents the peritoneal dissemination of scirrhous gastric carcinoma

PURPOSE

Transforming growth factor beta receptor (TGFbeta-R) is reported to correlate with the malignant potential of scirrhous gastric carcinoma. The aim of the current study is to clarify the possibility of molecular target therapy with a TGFbeta-R inhibitor, A-77, for the treatment of peritoneal dissemination of scirrhous gastric cancer.

EXPERIMENTAL DESIGN

Three scirrhous gastric cancer cell lines and two fibroblasts were used. For in vivo experiments, the A-77 was administered i.p. to mouse models of peritoneal dissemination. The influences of A-77 on the adhesion ability, invasion ability, and the expression of adhesion molecules were examined in vitro.

RESULTS

The A-77 administration resulted in a significantly (P < 0.01) better prognosis for the mice with peritoneal dissemination (median survival time, 51 days), compared with the control (median survival time, 25 days). A-77 therefore significantly (P < 0.01) decreased the weight and number of metastatic nodes. The adhesive ability and invasion ability of cancer cells were significantly decreased by A-77. A-77 decreased the expression of alpha(2), alpha(3), and alpha(5) integrins in gastric cancer cells. The histologic findings showed the degree of fibrosis to be less in the tumors treated by A-77. A-77 decreased the growth of fibroblast and invasion-stimulating activity of fibroblasts on cancer cells.

CONCLUSION

The TGFbeta-R inhibitor, A-77, decreased the expression of integrins in cancer cells and the proliferation of fibroblasts, which resulted in the decreased adhesive and invasive abilities of scirrhous gastric cancer cells to peritoneum. A-77 is thus considered to be useful for the inhibition of peritoneal dissemination of scirrhous gastric carcinoma.

A synergic inhibitory-effect of combination with selective cyclooxygenase-2 inhibitor and S-1 on the peritoneal metastasis for scirrhous gastric cancer cells

An inhibitory-effect of a selective cyclooxygenase-2 (COX-2) inhibitor on peritoneal metastasis of scirrhous gastric carcinoma was investigated in vivo. Peritoneal metastasis had developed after intraperitoneal inoculation of scirrhous gastric cancer cells, OCUM-2MD3, in nude mice. COX-2 inhibitor and/or S-1 were administered orally in nude mice with peritoneal metastasis. Oral administration of COX-2 inhibitor and S-1 significantly prolonged survival rates of these nude mice, compared with either alone. These findings suggested that combining S-1 and COX-2 inhibitor administration obtain a synergistic inhibitory-effect on the peritoneal metastasis of scirrhous gastric carcinoma.

Modulation of E-cadherin by hepatocyte growth factor induces aggressiveness of gastric carcinoma

OBJECTIVE

Hepatocyte growth factor (HGF) is well known as a scatter factor because it can disperse cells. E-cadherin is a protein that plays a main role in the establishment of cell-cell adhesion. This study focused on the role of HGF on the expression and distribution of E-cadherin. Furthermore, we found induction of aggressiveness of gastric carcinoma by modulation of E-cadherin by HGF.

MATERIALS AND METHODS

Tumor tissues from 50 patients with gastric carcinoma were evaluated for the expression of HGF, its receptor c-Met, and E-cadherin. Western blot analysis and invasion assay were performed to confirm the role of HGF on the modulation of E-cadherin using human gastric cancer cell lines.

RESULTS

Seventy-eight percent of the gastric carcinoma tissues showed overexpression of c-Met. E-cadherin expression was found in 86%, which could be further classified as membranous type (52%) or nonmembranous type (48%). The levels of HGF in tumor tissues increased significantly according to the tumor progression. The levels of HGF in tumors with nonmembranous type E-cadherin expression were significantly higher than those in tumors with membranous expression. A striking morphologic change from epithelial shape to fibroblastic shape was observed in SNU-16 cells after 3 days' exposure to HGF, accompanied by down-regulation of functional E-cadherin in the membrane. Treatment of the cells with HGF induced significant invasion into the matrigel.

CONCLUSION

We can conclude that HGF can modulate the expression of E-cadherin in gastric carcinoma, which was accompanied by more aggressive phenotype.

Effect of organ-specific fibroblasts on proliferation and differentiation of breast cancer cells

Breast carcinomas contain both tumor cells and stromal cells, including fibroblasts, endothelial cells, and lymphocytes. Proliferation of breast cancer cells may be controlled partly by mesenchymal cells, especially fibroblasts. We studied effects of fibroblasts on tumorigenicity and histologic features of breast cancer cells vivo, and analyzed fibroblast-produced growth-promoting factors in vitro. Breast carcinoma cells from four lines, and fibroblasts from lines obtained from skin and breast tissue of four patients with breast cancer were used. A suitable number of breast tumor cells and fibroblasts were inoculated subcutaneously into nude mice; resulting tumors were examined. Then conditioned medium from fibroblasts was added to cultures of breast cancer cells to study growth effects, and growth-promoting factors from breast fibroblasts were analyzed. Co-inoculation of breast cancer cells with breast fibroblasts into mice significantly increased tumorigenicity and tumor size beyond those obtained with breast cancer cells alone. Histologically, tumors resulting from co-inoculation with breast fibroblasts showed a scirrhous pattern with extensive fibrosis, while those formed by breast cancer cells injected alone or co-inoculation with skin fibroblasts showed a solid pattern. Medium from breast fibroblasts significantly increased breast cancer cell growth in vitro, while the various skin fibroblasts did not all show this effect. Structural and functional interactions between organ-specific fibroblasts and breast cancer cells may importantly regulate breast cancer growth and progression.

Inhibitory effect of a selective cyclooxygenase inhibitor on the invasion-stimulating activity of orthotopic fibroblasts for scirrhous gastric cancer cells

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 x 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.

Suppression of peritoneal implantation of gastric cancer cells by adenovirus vector-mediated NK4 expression

Peritoneal dissemination is the most common mode of metastasis in gastric cancer. We previously reported the importance of milky spots (MS), peritoneal lymphoid tissues, as selective sites of cancer implantation in peritoneal dissemination. In the present study, we first demonstrated that intraperitoneal injection of adenovirus vector encoding the GFP gene into tumor-free nude mice resulted in GFP expression at omental and mesenteric MS; MS macrophages were target cells for adenovirus infection. We confirmed that intraperitoneal injection of adenovirus vector encoding the NK4 gene (AdNK4) resulted in NK4 production localized to the peritoneal cavity, especially the omentum. Adenovirus vector-mediated MS-selective transgene expression was markedly impaired in tumor-bearing mice whose MS had already been replaced by infiltrating cancer cells. However, prior injection of AdNK4 successfully inhibited MS-selective cancer cell implantation, resulting in suppression of peritoneal dissemination and prolongation of survival. Adenovirus vector-mediated MS-selective delivery of a therapeutic gene may prevent peritoneal dissemination of gastric cancer.

Dual mode regulation of migration by lysophosphatidic acid in human gastric cancer cells

Lysophosphatidic acid (LPA), which interacts with at least three G protein-coupled receptors (GPCRs), LPA1/Edg-2, LPA2/Edg-4, and LPA3/Edg-7, is a lipid mediator with diverse effects on various cells. Here, we investigated the expression profiles of LPA receptors and patterns of LPA-induced migration in gastric cancer cells. Northern blot analysis revealed that various gastric cancer cells expressed variable levels of LPA1, LPA2, and LPA3 without a consistent pattern. Using a Boyden chamber assay, LPA markedly increased cell migration of LPA1-expressing cells, the effects of which were almost totally abrogated by Ki16425, an LPA antagonist against LPA1 and LPA3. In contrast, LPA by itself did not significantly induce migration in MKN28 and MKN74 cells, which exclusively expressed LPA2. However, when hepatocyte growth factor (HGF) was placed with LPA in the lower chamber, LPA induced migration of these cells in a dose-dependent manner. Immunoprecipitation analysis revealed that LPA induced transient tyrosine phosphorylation of c-Met in LPA2-expressing cells, which suggests that the transactivation of c-Met by LPA causes a cooperative migratory response with HGF to these cells. Our results indicate that LPA regulates the migration of gastric cancer cells in a receptor-specific manner and suggest that the expression pattern of LPA receptors may affect the metastatic behavior of gastric cancer.

Phenotypic switch from paracrine to autocrine role of hepatocyte growth factor in an androgen-independent human prostatic carcinoma cell line, CWR22R

Support mechanisms involved in growth of androgen-independent prostate cancer are primarily unknown. Hepatocyte growth factor (HGF)/Met has been suggested to be one of them based primarily on immunohistochemical studies. We conducted a series of experiments to assess the role of the HGF/Met system in an androgen-dependent human prostate carcinoma, CWR22 and its androgen-independent derivative, CWR22R. We found that action of HGF changed from paracrine to autocrine in progression to androgen-independent state. CWR22 tumors did not express HGF but expressed Met, whereas prostate stromal cells expressed HGF at a high level. Growth of CWR22 was stimulated either by addition of HGF to the culture or by the presence of prostate stromal cells. On the other hand, CWR22R cells expressed both HGF and Met. Knockdown of Met expression by RNA interference method suppressed the growth of CWR22R cells. Our data suggest that HGF is intimately involved in growth of human prostate cancer and that progression from the androgen-dependent to the androgen-independent state is associated with an adaptive switch in support mechanism from paracrine to autocrine. Our data offer one mechanism to account for androgen-independent human cancer growth.

Involvement of Arp2/3 complex in the process of colorectal carcinogenesis

Increased motility is one of the characteristics of cancer cells, and actin polymerization and disassembly are essential for cellular motility. Since actin-related protein (Arp) 2/3 complex acts as a nucleus for actin polymerization, in this study, we immunohistochemically investigated the expression of Arp2 and Arp3 in 175 colorectal tumors in various stages of neoplastic progression. Arp2 and Arp3 showed identical expression patterns, and both were expressed in the stromal cells around neoplastic tubules or glands and in the tumor cells themselves. The frequency of expression of Arp2 and Arp3 (Arp2 and 3) by the stromal cells increased with the atypia of the colorectal neoplasms, from 5.5% (3/55) in adenoma with mild or moderate atypia, to 11.8% (2/17) in adenoma with severe atypia, 53.3% (16/30) in intramucosal carcinoma, and 91.8% (67/73) in invasive carcinoma (P<0.0001). The frequency of expression of Arp2 and 3 in the tumor cells was similar and was 1.8% (1/55) in adenoma with mild or moderate atypia, 23.5% (4/17) in adenoma with severe atypia, 23.5% (7/30) in intramucosal carcinoma, and 32.9% (24/73) in invasive carcinoma. Expression of Arp2 and 3 by the stromal cells was significantly correlated with nuclear accumulation of p53 in the tumor cells and stromal expression of CD10. These results suggest that formation of Arp2/3 complex by both neoplastic and stromal cells contributes to the increased motility of both cell types and thus provides suitable conditions for invasion.

Gene transduction of NK4, HGF antagonist, inhibits in vitro invasion and in vivo growth of human pancreatic cancer

In this study, we investigated the therapeutic effects of adenovirally-mediated transfer of the sequence of NK4, an antagonist for hepatocyte growth factor (HGF), against human pancreatic carcinoma. HGF has been implicated to play an important role in invasion and metastasis of various human cancers through tumor-stromal interactions. Although NK4 has been shown to block the metastatic behavior of cancer cells, problems with cellular delivery of NK4 must be addressed before it can be used for clinical trials. The effects of NK4 gene transduction mediated by recombinant adenovirus (Ad-NK4) were evaluated in a human pancreatic cancer cell line (SUIT-2) by in vitro scattering assays, invasion assays, and subcutaneous transplantation in nude mice. NK4 transduction markedly inhibited scattering and invasion of SUIT-2 cells stimulated by HGF without affecting cell proliferation in vitro. Furthermore, Ad-NK4 significantly inhibited the growth of tumors transplanted to nude mice. The tumor reduction induced by Ad-NK4 was associated with a decreased number of blood vessels surrounding the tumors. These findings suggest that Ad-NK4 gene therapy may be a unique and promising strategy for the treatment of pancreatic cancer.

Enhancement of tumorigenic, metastatic and in vitro invasive capacity of rat mammary tumor cells by transforming growth factor-beta

We investigated the effects of transforming growth factor-beta (TGF-beta) on biological behavior of a weakly malignant rat mammary carcinoma ER-1 cell line. TGF-beta enhanced the tumorigenic and metastatic capacity of ER-1 cells and their in vitro invasiveness to rat mesothelial and endothelial cell. Further cell biological analysis indicated that the increased invasive and metastatic capacity of ER-1 cells by TGF-beta was due to the increase in cell motility and adhesion to the mesothelial and endothelial cell monolayers. Thus, it is suggested that TGF-beta acts on ER-1 cells as a progression-enhancing factor which stimulates their adhesive and motile activities.

Overexpression of the c-met protooncogene in human gastric carcinoma--correlation to clinical features

Overexpression of hepatocyte growth factor receptor (c-met) has been detected in many human tumors. To investigate the possible involvement of c-met in human gastric carcinogenesis, we examined c-met expression in 45 patients with gastric carcinoma using Northern blot analysis, reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemical staining. The c-met mRNA expression was increased twofold and sevenfold in gastric carcinoma tissues compared to the adjacent normal tissues by Northern blot analysis and RT-PCR, respectively. In the immunohistochemical study, c-met protein was detected in 32 of 45 (71.1%) patients, with marked overexpression in gastric carcinoma compared with matched normal gastric tissues. The c-met-positive immunoreactivities were more frequently encountered in serosa-exposed and serosa-infiltrating gastric cancer (p = 0.003). In addition, tumor stage was another statistically significant parameter that was observed between the two groups (p = 0.02). Multivariate analyses revealed that the tumor stage (p = 0.014) and c-met overexpression (p = 0.031) were independently correlated with survival. These data suggest that overexpression of c-met may play a part in gastric carcinogenesis and may represent a prognostic factor for gastric cancer.

Hepatocyte growth factor induces colonic cancer cell invasiveness via enhanced motility and protease overproduction. Evidence for PI3 kinase and PKC involvement

Tumour progression to the metastatic phenotype is mainly dependent on tumour cell invasiveness. Cell migration is a crucial step in this process. Here we investigate the effect of hepatocyte growth factor (HGF) on the induction of in vitro invasiveness of poorly aggressive Caco-2 colonic cancer epithelial cells. Invasion assays through a Matrigel barrier were performed. Proteases were assessed by zymography, reverse transcription-polymerase chain reaction and immunoblotting. Caco-2 cells were found to express HGF receptor but not HGF and to secrete several proteases, namely matrix metalloproteinase-1 (MMP-1), MMP-2, possibly MMP-9 and urokinase plasminogen activator (uPA). Exogenous HGF promoted invasiveness of Caco-2 cells through an artificial basement membrane matrix and enhanced their production of proteases. In addition, analyses of media at the end of invasion assays indicated that anti-HGF antibody inhibited protease production in parallel with cell invasion. The involvement of proteases in the HGF-induced invasion process was further investigated using either a synthetic general MMP inhibitor or neutralizing antibodies against MMPs or uPA. All components significantly inhibited HGF-promoted cell invasion. Moreover, specific inhibitors of PKCalpha/beta1 and PI3 kinase also decreased both HGF-promoted cell invasion and protease expression in invasion assay media. Thus, our findings provide evidence that the process of HGF-activated invasiveness of Caco-2 cells involves PI3 kinase and PKC and results from close association of two events, stimulation of cell motile activity and concomitant overproduction of proteases, which permits cell migration through a degraded extracellular matrix.

M(R) 77 KDA factor derived from fibroblasts stimulates the invasion ability of breast-cancer cells

Breast-cancer cells frequently invade into the skin. However, few reports have described the mechanisms responsible for this invasion. In this study, we investigated the effects of skin fibroblasts on the invasion ability of breast-cancer cells, using a modification of Boyden's chamber method, and purified an invasion-stimulating factor from fibroblasts. Conditioned medium of skin fibroblasts, DF-1, significantly stimulated the invasion ability of breast-cancer cells, OCUB-1. The invasion-stimulating factor produced from skin fibroblasts was then partially purified and characterized. The soluble invasion-stimulating factor of fibroblasts was a protein of 77 kDa, as calculated by SDS-PAGE. Although TGF-alpha and bFGF stimulated the invasion of OCUB-1, no inhibition of the 77 kDa factor was achieved with neutralizing antibodies against TGF-alpha and bFGF. These findings suggest that the 77 kDa factor derived from skin fibroblasts might be unique, might play an important role in invasion to the skin and might explain the frequent skin invasion in breast carcinoma.

NK4, a four-kringle antagonist of HGF, inhibits spreading and invasion of human pancreatic cancer cells

Because of the highly aggressive behaviour, i.e. invasive, disseminative and metastatic properties, the outcome for patients with pancreatic cancer is morbid. A better understanding and interference with the malignant behaviour of pancreatic cancer may provide new directions for treatment. We report here the induction of highly motile and invasive properties in human pancreatic cancer cells by hepatocyte growth factor (HGF) and blockage of these properties by NK4, a newly identified antagonist for HGF. In all of eight human pancreatic cancer cell lines we used (AsPC-1, BxPC-3, H-48N, KP-1N, KP-2, KP-3, MIA PaCa-2 and SUIT-2 cells), the c-Met/HGF receptor was expressed at varying levels. Although weak mitogenic activity of HGF was seen only in SUIT-2 and KP-3 cells, HGF strongly stimulated migration and invasion of these pancreatic cancer cells, except for BxPC-3 and MIA PaCa-2 cells. In contrast, migration and invasion potently induced by HGF in KP-1N, KP-3 and SUIT-2 cells were inhibited by NK4. The invasion of SUIT-2 cells was also potently stimulated with the influence of cocultured pancreatic fibroblasts and by ascitic fluid obtained after pancreatic cancer resection, however, invasiveness of the cancer cells in such conditions was practically abolished by NK4. Consistently, the ascitic fluid in patients who had undergone pancreatic cancer surgery contained high levels of HGF. These findings mean that HGF is probably involved in invasion, dissemination, and metastasis of pancreatic cancer, particularly through tumour-stromal interaction and after resection of the pancreatic cancer. NK4, an effective antagonist of HGF, may prove to have the potential for anti-invasion/metastasis.

Hepatocyte growth factor secreted by prostate-derived stromal cells stimulates growth of androgen-independent human prostatic carcinoma cells

The objective of the present study is to examine the role of prostate stromal cells on growth and progression of prostate cancer. Co-inoculation of androgen-independent carcinoma cells (PC-3 and CA-7T2) with prostate-derived stromal (P-ST) cells significantly enhanced the growth of carcinoma cells in athymic nude mice. For the in vitro study, a three-dimensional co-culture system was used. It consisted of two layers of collagen gel. Stromal cells were suspended in the lower layer, whereas cancer cells were suspended in the upper layer. Compared to the control culture, the presence of P-ST cells in the lower collagen layer significantly stimulated the growth of carcinoma cells. Such an effect was not demonstrated when carcinoma cells were co-cultured with either bone marrow-derived or skin-derived stromal cells. We identified hepatocyte growth factor (HGF) as the principal growth factor released by P-ST cells but not by bone marrow-derived or skin-derived stromal cells. Neutralizing antibodies against HGF completely abrogated the stimulatory effect of P-ST cells. Exogenous HGF likewise stimulated the growth of carcinoma cells in vitro and in vivo. These results suggest that HGF produced by P-ST cells is a paracrine growth factor that stimulates the growth of androgen-independent prostate cancer cell lines.

Tumor thickness is a histopathologic predictive parameter of tumor metastasis and prognosis in patients with Dukes stage C ulcerative-type colorectal carcinoma. A two-hospital-based study

BACKGROUND

Metastasis to the liver or lymph nodes is an important prognostic factor in patients with colorectal carcinoma. The purpose of the current study was to estimate the power of tumor thickness in predicting metachronous liver metastasis (MLM), lymph node metastasis (LNM), or overall survival (OS) in patients at two hospitals (the National Cancer Center Hospital [NCCH] and the National Cancer Center Hospital East [NCCHE]) to confirm the reproducibility of the study.

METHODS

The subjects of this study were 74 and 186 consecutive patients with ulcerative-type colorectal carcinoma treated at the NCCH and NCCHE, respectively. Tumor thickness was measured in three areas: 1) the marginal elevated area (MEA), 2) the central depressed area (CDA), and 3) the most thickened area (MTA). Studies were performed with well known histologic parameters to compare the predictive power of tumor thickness on MLM, LNM, and OS using the Cox proportional hazards regression model or analysis of variance.

RESULTS

A significant correlation between tumor thickness and MLM was observed only in the CDA in the NCCH patients (P = 0.005). The authors applied a tumor thickness cutoff value in the CDA of 10 mm (</= 10 mm and > 10 mm) for further study. Multivariate analyses demonstrated that a tumor CDA thickness > 10 mm was associated significantly with MLM, multiple LNMs, and OS in NCCH patients with Dukes Stage C disease (P = 0.002, P = 0.023, and P = 0.002, respectively). A significant predictive power for tumor CDA thickness for MLM, multiple LNMs, and OS was confirmed by multivariate analysis in NCCHE patients with Dukes Stage C disease (P = 0.008, P = 0.021, and P = 0.010, respectively).

CONCLUSIONS

The CDA thickness of the tumor was found to be a useful predictive parameter for MLM, multiple LNMs, and OS in patients with Dukes Stage C ulcerative-type colorectal carcinoma who were being treated in two independent hospitals.

The association of transforming growth factor-beta 1 with myometrial invasion of endometrial carcinomas through effects on matrix metalloproteinase

OBJECTIVE

The association of transforming growth factor-beta 1 (TGF-beta 1) with a matrix metalloproteinase (MMP) and a tissue inhibitor of metalloproteinase (TIMP), as well as myometrial invasion of endometrial cancer was studied.

METHODS

The effects of TGF-beta 1 on cellular invasiveness, gelatinase activity, and expression of TIMP-1 were examined in 2 endometrial adenocarcinoma cell lines, KLE and Ishikawa. Plasma was obtained from 8 endometrial cancer patients with Stage-Ia disease, from 6 with Stage-Ib disease, and from 4 with Stage-Ic disease, and the levels of TGF-beta 1 were measured by enzyme immunoassays. The immunohistochemical expression of MMP-9, TIMP-1, TGF-beta 1, and TGF-beta receptor Type I in tumor tissue from the same patients also was detected.

RESULTS

Invasiveness, gelatinase activity, and the expression of TIMP-1 were higher in KLE cells than in Ishikawa cells, and they were increased by treatment with rTGF-beta 1. The expression of TGF-beta receptor Type I was higher in KLE cells than in Ishikawa cells, which were unresponsive to exogenous TGF-beta 1. The plasma levels of TGF-beta 1 were greater in Stage-Ib and Stage-Ic patients than in Stage-Ia patients. MMP-9 and TGF-beta receptor Type I were expressed mainly in tumor cells, while TIMP-1 and TGF-beta 1 were localized in both tumor epithelial cells and stromal cells. MMP-9 and TIMP-1 were expressed only in Stage-Ib and Stage-Ic patients, although TGF-beta 1 and TGF-beta receptor Type I were ubiquitous.

CONCLUSIONS

Myometrial invasion of endometrial cancers involves an increase in gelatinase activity, regulated to some extent by TGF-beta 1 in an autocrine or paracrine fashion.