Peritoneal metastatic model for human scirrhous gastric carcinoma in nude mice

We established a peritoneal-metastatic model for scirrhous gastric carcinoma. Peritoneal metastasis had developed after intraperitoneal inoculation of OCUM-2MD3 cells in nude mice. This cell line was derived from a peritoneal-metastatic nodule at the mesenterium after orthotopic implantation of OCUM-2M cells which developed no peritoneal metastasis after intraperitoneal inoculation. The histologic findings of orthotopic-implanted tumor in the stomach show scirrhous type while those of subcutaneous-implanted tumor show medullary type. There might be factors, in OCUM-2MD3 cells, which are responsible for peritoneal metastasis. We next investigated the differences in the biological behavior of the original OCUM-2M and the derived variant OCUM-2MD3. Morphology and growth activity of the two cell lines were similar to each other. The specific chromosomes, add(6)(g13), del(7)(q21.2) and inv(11)(pl3q21), were found in OCUM-2MD3 cells but not in OCUM-2M cells. While the oncogenes amplification by OCUM-2M cells was found in K-sam and c-myc, that by OCUM-2MD3 cells was found only in c-myc. The expression of E-cadherin by OCUM-2MD3 cells was decreased compared with that of OCUM-2M cells. Expression level of β1-integrin of OCUM-2MD3 cells was higher than that of OCUM-2M cells. The binding and invasion activity of OCUM-2MD3 cells were higher than those of OCUM-2M cells, and were decreased by anti-β1-integrin antibody. The invasion activity of OCUM-2MD3 cells was increased in the presence of peritoneal fibroblast. In this study, it was suggested that orthotopic implantation of cancer cells might have an effect on the acquisition of metastatic ability. β1-integrin and peritoneal fibroblasts might be correlated with peritoneal metastasis. This peritoneal-metastatic model should be useful for analysing the mechanism of peritoneal metastasis of human scirrhous gastric cancer.     

Establishment of lymph node metastatic model for human gastric cancer in nude mice and analysis of factors associated with metastasis

The actual mechanisms responsible for lymph node metastasis in gastric cancer are still unclear. To investigate the mechanisms of lymph node metastasis in gastric cancer, we established a lymph node metastatic model for human scirrhous gastric carcinoma. Lymph node metastasis had frequently developed after orthotopic implantation of OCUM-2M LN derived from a scirrhous gastric cancer cell line, OCUM-2M, which had low capacity for lymph node metastasis. We elucidated the different characteristics including binding ability, migratory capacity and immunoresponses induced by the cell surface molecules of these two cell lines. The binding ability to Matrigel and migratory capacity of OCUM-2M LN cells were significantly greater than those of OCUM-2M cells. On flow cytometric analysis, both OCUM-2M and OCUM-2M LN cells strongly expressed HLA-I (99.5 and 97.1%) and LFA-3 (76.6 and 99.2%) in level of expression between the two cell lines, but neither cell line expressed HLA-II (0.0 and 0 .0%), B7-1 (0.0 and 0.0%) or B7-2 (0.4 and 0.3%). ICAM-1 expression in OCUM-2M LN cells was weaker (0.7%) than that in OCUM-2M cells (36.8%). Strong adhesiveness and cytotoxicity of mononuclear lymphocytes for OCUM-2M cells were observed in adhesion and cytotoxic assays, both of which were significantly decreased by the addition of anti-ICAM-1 antibodies. On the other hand, the adhesiveness and cytotoxicity of OCUM-2M LN cells were significantly less than those of OCUM-2M cells, and were not affected by the addition of anti-ICAM-1 antibodies. These findings suggest that decreased ICAM-1 expression in a new gastric cancer cell line with a high rate of lymph node metasta-sis may in turn decrease immune responses mediated through LFA-1-dependent effector cell adhesion, and that this escape from the immunosurveillance system may be one of the factors inducing lymph node metas-tasis. In conclusion, we established a gastric cancer cell line, OCUM-2M LN, with a high rate of lymph node metasta sis. An in vivo lymph node-metastatic model with this cell line should be useful for analysing the mech-anism and therapeutic approach of lymph node metastasis. © Rapid Science Ltd.     

Lipid-mediated gene transfection of intercellular adhesion molecule-1 suppresses the peritoneal metastasis of gastric carcinoma

We have previously reported that a decreased expression level of ICAM-1 in cancer cells frequently led to the development of lymph node metastasis, and suggested that ICAM-1 gene transfection may inhibit lymph node metastasis. In the present study, we investigated whether ICAM-1 gene therapy for the peritoneal metastasis of gastric carcinoma is useful as a new immuno-gene therapy. ICAM-1 gene was transfected into a gastric cancer cell line, OCUM-2MD3 (2MD3), which has a high metastatic ability to the peritoneum. A transfectant cancer cell line, 2MD3/ICAM-1, had high ICAM-1 expression on the cell surface. The adhesion and cytotoxicity abilities of peripheral blood mononuclear cells were significantly increased against 2MD3/ICAM-1 cells in comparison with 2MD3 cells. Mice inoculated with 2MD3/ICAM-1 cells in the peritoneal cavity had a significantly better survival rate than those inoculated with 2MD3 cells (log-rank test, p<0.05). Histologic findings revealed that more mononuclear cells existed around the metastatic nodules in 2MD3/ICAM-1. Although gastric carcinoma frequently causes peritoneal metastasis, no useful therapy for the metastasis of gastric carcinoma has been developed. These findings revealed that ICAM-1 gene transfection to cancer cells could be a useful immuno-gene therapy for the peritoneal metastasis of gastric carcinoma.     

TNF-α promotes progression of peritoneal metastasis as demonstrated using a green fluorescence protein (GFP)-tagged human gastric cancer cell line

The mechanisms underlying progression of peritoneal metastasis by gastric cancer after micrometastasis formation remain unclear. In the present study, we investigated metastasis to the abdominal wall peritoneum, one of the major features of peritoneal spread, using a human gastric cancer cell line (GCIY-EGFP) tagged with the green fluorescence protein gene (GFP). This model allows sensitive, specific and sequential observation of metastasis development from the initial deposits to peritoneal carcinomatosis at the end stage. In the initial phase, GCIY-EGFP cells could form micrometastasis selectively on the omentum and mesenterium in a milky spot-dependent manner, but not on abdominal wall peritoneum lacking milky spots until the late stages. In vitro analysis using primary mesothelial cells revealed addition of TNF-alpha to decrease their stress fibers, leading to morphological change followed by exposure of the submesothelial extracellular matrix (ECM) in intercellular gaps. Such TNF-alpha pretreatment was found to enhance attachment of tumor cells to the mesothelial monolayer. When tumor cells were injected into the peritoneal cavity of TNF-alpha pretreated mice, they could metastasize to the abdominal wall peritoneum from the very early stages, resulting in accelerated accumulation of ascites than in TNF-alpha non-pretreatment controls. RT-PCR analysis revealed that tumor cells express cytokines and chemokines, including TNF-alpha. Furthermore, TNF-alpha treatment results in up-regulation of expression of monocyte chemoattractant protein-1 (MCP-1) and IL-8 by mesothelial cells and of TNF-alpha itself by inflammatory leukocytes in the peritoneal cavity. These results suggest that metastasis to the abdominal wall peritoneum occurs as a second step from the first omental metastasis in a milky spot-independent manner and that TNF-alpha derived from tumor cells, mesothelial cells and inflammatory leukocytes in the peritoneal cavity may be involved in the progression of peritoneal metastasis.     

Effects of Hydrocortisone on Peritoneal Phagocytizing Cells in Rats under Conditions of β-Adrenoceptors Blockade

Hydrocortisone decreased the count of peritoneal mononuclear phagocytes and mast cells and total phagocytic activity of peritoneal phagocytes in rats, but had no effect on the nitroblue tetrazolium test. -Adrenoceptor blockade abolished the suppressive effect of hydrocortisone on phagocytosis and prevented the decrease in the count of mast cells, but markedly reduced the number of neutrophils and parameters of stimulated nitroblue tetrazolium test.     

Epidermal growth factor,transforming growth factor-α, and epidermal growth factor receptor content in normal and carcinomatous gastric and colonic tissue

Summary Epidermal growth factor (EGF) and transforming growth factor- (TGF-) are polypeptides which bind to the EGF receptor (EGFr) and may play a role in cell growth and carcinogenesis. Our study investigated the content of EGF, TGF-, and EGFr in tumors of the stomach and the colon in comparison with the sourrounding mucosa. EGF was detected in half of the stomach specimens with concentrations between 1 and 9 ng/g weight irrespective of histology. In the colon no EGF was found in the tumor or normal mucosa. In the stomach normal mucosa contained higher TGF- concentrations (mean 22.4 ng/g) than the tumors (mean 11.8 ng/g), but the difference was not statistically significant because of a wide variation in mucosal values. By contrast, the colon mucosa displayed significantly higher TGF- concentrations than the tumor tissues (33 ng/g versus 12 ng/g; P < 0.01). EGFr content in the gastric mucosa was lower compared to gastric carcinoma (48 fmol/g versus 75 fmol/g) yet not significantly different. In contrast, colorectal tumor specimens disclosed significantly higher concentrations than the mucosal tissues (mean of 155 fmol/g versus 80 fmol/g; P < 0.01). In conclusion, TGF- should not be considered a tumorigenic but a physiological growth factor in the stomach and colon. An elevated EGFr content in colorectal tumors in comparison with the normal mucosa could lead to a growth advantage by an autostimulating mechanism.Abbreviations EGF epidermal growth factor - EGFr epidermal growth factor receptor - TGF- transforming growth factor - ROC receiver operating characteristic Dedicated to Prof. Dr. G. Paumgartner on the occasion of his 60th birthday     

Integrin-mediated entry into S phase of human gastric adenocarcinoma cells

The integrins are a family of integral membrane receptors that participate in binding to various extracellular and cell surface proteins during adhesion, migration, and homing of normal and neoplastic cells. In this study, we characterized the involvement of integrins in mediating the growth of an adhesion-dependent gastric adenocarcinoma line, ST2. This line was distinguished and selected for study based on its inability to grow when suspended in soft agar or plated on poly(2-hydroxyethyl methacrylate)-coated dishes. ST2 cells arrested in G0/G1 of the cell cycle when deprived of adhesion to substrate. Using purified matrix components, collagen was found to be highly active in promoting 1 integrin-mediated cell attachment and spreading. Subsequent to spreading on collagen, the cells were released from G0/G1 block and progressed into S phase. Monoclonal antibodies to 2 or 1 integrin blocked the reinduction of both cell spreading and entry into S phase. These studies suggest that during the metastatic process, integrin receptor interaction with the insoluble matrix may be an important step leading to proliferation of some tumors.     

Embolization of mesothelial cells in lymphatics: the route to mesothelial inclusions in lymph nodes?

Aims : To provide evidence that lymphatic embolization is the mechanism for mesothelial inclusions in lymph nodes.  

Methods and results

A 60-year-old man with alcoholic cirrhosis and ascites had an umbilical hernia resected. The herniorrhaphy specimen contained numerous dermal and submesothelial lymphatic vessels filled by cells similar to the cells that lined the hernia sac. Most of the cells in lymphatics were submesothelial reactive cells, whose cytoplasm stained with antibodies against cytokeratins (AE1–AE3; 8,18), smooth muscle actin, vimentin, desmin and tissue polypeptide antigen (TPA). Some cells seemed to be superficial mesothelial cells, being positive with high molecular weight anticytokeratin antibody 34βE12. On ultrastructural study submesothelial cells with intermediate cytoplasmic filaments, rough endoplasmic reticulum and primitive cell junctions, and scanty superficial mesothelial cells with microvilli, tonofilaments and desmosomes were found in the lymphatics.  

Conclusions

Lymphatic dissemination of mesothelial and submesothelial cells is an uncommon and not well known phenomenon. Lymphatic dissemination is probably the route by which the mesothelial cells reach the lymphatic nodes. These cells may be mistaken for malignant cells.     

Effects of tumour necrosis factor α and interleukin 1 β on the proliferation of cultured glomerular epithelial cells

Rat glomerular epithelial cells were cultured with human monocyte supernatant or with recombinant cytokines. A primary glomerular culture and a glomerular epithelial cell culture were made; supernatant from monocyte cultures derived from healthy humans, and recombinant tumour necrosis factor (TNF ) or recombinant interleukin 1 (IL-1 ) were added. Cell proliferation rates were assayed by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. In serum-free media, consistent proliferation of glomerular epithelial cells (GEC) was observed throughout the 3 week culture period. Significant growth-stimulatory effects were induced by lipopolysaccharide-treated monocyte conditioned medium and by 1–50 ng/ml of TNF , growth being up to 400% more than in the control culture. The effect of TNF depended mainly on its interaction with epidermal growth factor (EGF). In contrast to TNF , IL-1 inhibited GEC proliferation; this was due to the early appearance and proliferation of mesangial cells, despite the culture being serum-free. This study showed that activated monocytes secrete growth factors for GEC in vitro, and that interaction between both TNF and IL-1 and between TNF and EGF can modulate GEC proliferation. These findings suggest that, under pathological conditions, monocytes or macrophages affect GEC proliferation, probably being involved in crescent formation.     

IFN-α Acts on T-Cell Receptor-Triggered Human Peripheral Leukocytes to Up-Regulate CCR5 Expression on CD4+ and CD8+ T Cells

Interleukin-12 (IL-12) as well as IL-2 was recently shown to up-regulate CCR5 expression on T-cell receptor (TCR)-triggered human T cells. Because of the functional similarity between interferon-alpha (IFN-) and IL-12, the present study investigated whether IFN- also up-regulates T cell CCR5 expression. CCR5 was marginally detected on T cells from unstimulated human peripheral blood leukocytes (PBLs) and only slightly induced on PBL T cells following stimulation with anti-CD3 plus anti-CD28 monoclonal antibodies (mAbs). When anti-CD3/anti-CD28-triggered PBLs were exposed to IFN-, T cells expressed high levels of CCR5. The levels of CCR5 expression were comparable to those induced by IL-12. However, when purified T cells instead of unfractionated PBL were stimulated with anti-CD3/CD28 and then exposed to IL-12 or IFN-, CCR5 expression was induced by IL-12 but not by IFN-. IFN- was found to act on anti-CD3/anti-CD28-stimulated PBL to promote their IL-12 production. Moreover, addition of anti-IL-12 mAb to IFN--stimulated cultures of anti-CD3/CD28-pretreated PBL resulted in considerable inhibition of CCR5 expression. Together, these results indicate that IFN- as well as IL-12 up-regulates CCR5 expression on TCR-triggered T cells and that IFN- functions not by acting directly on T cells but via enhancing IL-12 production by PBL.     

The selective modulation of endothelial cell mobility on RGD peptide containing surfaces by YIGSR peptides

The ability of the biomimetic peptides YIGSR, PHSRN and RGD to selectively affect adhesion and migration of human microvascular endothelial cells (MVEC) and vascular smooth muscle cells (HVSMC) was evaluated. Cell mobility was quantified by time-lapse video microscopy of single cells migrating on peptide modified surfaces. Polyethylene glycol (PEG) hydrogels modified with YIGSR or PHSRN allowed only limited adhesion and no spreading of MVEC and HVSMC. However, when these peptides were individually combined with the strong cell binding peptide RGD in PEG hydrogels, the YIGSR peptide was found to selectively enhance the migration of MVEC by 25% over that of MVEC on RGD alone (p<0.05). No corresponding effect was observed for HVSMC. This suggests that the desired response of specific cell types to tissue engineering scaffolds could be optimized through a combinatory approach to the use of biomimetic peptides.     

Glucocorticoids modulate TGF-beta production by human fetal lung fibroblasts

TGF- is thought to play a central role in pulmonary fibrosis inducing fibroblast differentiation and extracellular matrix synthesis. In human lung fibroblasts, it is still unclear how various TGF- isoforms affect TGF- production and whether glucocorticoids, commonly used agents to treat fibrotic lung disease, modulate these processes. To this end, human fetal lung fibroblasts (HFLF) were cultured with various concentrations of glucocorticoids (budesonide, dexamethasone or hydrocortisone) with and without TGF-1, -2, or -3. Post-culture media were collected for ELISA assays of TGF-1, -2, and -3 . TGF- mRNA was assessed by real time RT-PCR. Smad 2, 3, and 4 and AP-1 complex (c-fos and c-Jun) cellular localization were evaluated by immunostaining. TFG-2 and -3 stimulated TGF-1 production significantly (p < 0.01 relative to control). TGF-1 stimulated TGF-2 production (p < 0.01 relative to control). TGF-3 was undetectable. Glucocorticoids significantly inhibited TGF-1 and TGF-2 production and reduced expression of the up-regulated TGF-1 and TGF-2 mRNA induced by exogenous TGF-1, -2, or -3 (p < 0.01 for each) but had no effect on Smads. Although c-jun-related nuclear staining was not intensified in TGF--stimulated cells, it was reduced by glucocorticoids. Thus, TGF- isoforms may stimulate production of various TGF- isoforms in the lung. Glucocorticoids then may block TGF- production by modulating mRNA levels and c-Jun.     

Synoviocytes in chronic synovitis in situ and cytokine stimulated synovial cells in vitro neo-express α1, α3 and α5 chains of β1 integrins

The expression of the 1 integrins was examined immunohistochemically in synoviocytes from normal synovial membrane and from chronic synovitis of different aetiology and intensity. Normal synoviocytes were 61-positive but lacked 1 through 5. In mild inflammation type A synoviocytes neo-expressed 1, 3, and 5 chains. In severe inflammation both type A and B synoviocytes expressed 3, 4, 5, and 6 chains. The effects of inflammatory cytokines, as single agents or in combination, on the 1 integrin expression in cultured normal synoviocytes was determined by immunocytochemistry and flow cytometry. The 1 chain, while absent in unstimulated synoviocytes, was induced by interleukin-1 (IL-1), tumour necrosis factor- (TNF-), and interferon- (INF-). This effect was enhanced by combining IL-1 and TNF-. Expression of the 3 chain was up-regulated by IL-1 and, more intensely, by IFN-. Transforming growth factor (TGF-) inhibited the up-regulating effect of IL-1 and antagonized the effect of IFN- on 3 chain expression. Expression of the 5 chain was up-regulated significantly by co-stimulation through IL-1 together with TGF- or TNF-. Thus, the 1 integrin profile of cytokine activated synoviocytes in vitro resembled that of synoviocytes in synovitis in situ. These data suggest that IL-1, TNF-, IFN-, and TGF- are likely to be among the effectors regulating 1 integrin expression in synoviocytes in vivo.     

Immunomodulation by indoleamines: Serotonin and melatonin action on DNA and interferon-γ synthesis by human peripheral blood mononuclear cells

Different concentrations of indoleamines, serotonin and melatonin, inhibited phytohemagglutinin stimulated DNA synthesis. Thus, 10^–3 to 10^–4 M of either indoleamine acted at the optimal phytohemagglutinin concentration, while 10^–3 to 10^–7 M acted at suboptimal phytohemagglutinin levels. The serotonin effect was reversed by the serotonergic S₁-S₂ receptor antagonist methysergide but not by the S₂ antagonist ketanserin. This indicates that only the S₁ receptor is involved in the inhibitory effect. Inhibition of lymphoproliferation by indoleamines was also exerted on pokeweed mitogen and protein A fromStaphylococcus aureus stimulations. Serotonin and melatonin also inhibited phytohemagglutinin and protein A from Staphylococcus aureus induction of interferon- synthesis. The initial uptake of Ca²⁺ was not affected by indoleamines, suggesting that it is not the mechanism of their inhibitory effects. As interferon- induced tryptophan uptake by T lymphocyte- and macrophage-depleted populations, and tryptophan is the metabolic precursor of serotonin and melatonin, a new immunoregulatory circuit is postulated.     

Factors influencing serum neopterin and β2-microglobulin levels in a healthy diverse population

Sera and questionnaire data from a population-based random sample of healthy adults was used to evaluate factors influencing neopterin and 2-microglobulin (2m) values. Both neopterin and 2m levels increased with age and were higher among white than blacks (mean values for whites and blacks: neopterin, 5.06 vs 4.49 nmol/L; 2m, 1.36 vs 1.28 mg/L). Gender differences were noted for 2m but not neopterin values (2m males vs females: 1.37 vs 1.29 mg/L). Neopterin values were lower among current smokers than among nonsmokers (4.32 vs 5.16 nmol/L) and were higher among users of antihistamines (5.46 among users vs 4.65 nmol/L among nonusers). Neopterin and 2m were correlated in this healthy adult population (adjustedr=0.53,P=0.001), yet no other interrelationships with numerous biologic markers except between 2m and serum-soluble interleukin-2 receptor levels (adjustedr=.41,P=0.05) were observed. These findings provide important baseline information to consider before planning or evaluating studies utilizing neopterin or 2m levels.     

Evidence for the presence of pro-γ-melanotropin,the NH2-terminal fragment of the corticotropin-β-lipotropin precursor,in corticotropin-producing tumours

Summary Five corticotropin-producing tumours were examined for peptides related to the corticotropin--lipotropin precursor. Two were basophil pituitary adenomas and three were bronchial carcinoids. The cells of the two pituitary adenomas stained with antisera against -endorphin and against pro--melanotropin, the NH₂-terminal fragment of the corticotropin--lipotropin precursor, but not with antisera against -melanotropin or -lipotropin. The corticotropin-storing tumor cells of the bronchial carcinoids stained with antisera against -endorphin, -lipotropin or pro--melanotropin. Only one of the three bronchial carcinoids contained cells reacting with the antiserum against -melanotropin. Although the two types of corticotropin-storing tumours (pituitary adenoma and bronchial carcinoid) differed with respect to -lipotropin content, the over-all picture indicates that the proteolytic processing of the corticotropin precursor proceeds along similar lines in tumour cells and in pituitary corticotrophs.An acetic acid extract of one of the bronchial tumours was subjected to gel chromatography and immunochemical analysis of material related to pro--melanotropin. The immunoreactive material displayed a considerable size heterogeneity, with the predominant components having a molecular weight larger than that of authentic pro--melanotropin.     

Expression of Interferon Inducible Genes Following Hantaan Virus Infection as a Mechanism of Resistance in A549 Cells

Hantaan virus (HTN) is a causative agent of hemorrhagic fever with renal syndrome (HFRS). Little is known of its pathogenesis or the molecular mechanisms underlying resistance to HTN infection. In the present study, DNA microarray technology was used to monitor changes in mRNA levels after HTN infection, to elucidate resistance mechanisms to viral infection by understanding virus–host interactions. We found that several interferon (IFN)-inducible genes were up-regulated in host cells infected with HTN. According to previous available data, IFNs have been reported to be inhibitory, but their mode of action has not been yet clear. In this study, the 2,5-oligoadenylated synthetase (OAS) and M_x1 genes, not a double-stranded RNA-dependent protein kinase R (PKR), of the IFN response pathways are associated with antiviral activity during HTN infection. Furthermore, A549 cells treated with IFN- were protected against HTN infection. Taken together, these results confirmed that IFN plays a role in cellular defenses against HTN infection at an early stage of the infection and revealed the resistance mechanism for HTN infection.     

Interferon β1a Treatment Modulates TH1 Expression in γδ + T Cells from Relapsing-Remitting Multiple Sclerosis Patients

A paradigm exists that multiple sclerosis is causally related to dysregulation of T_H1 inflammatory cytokines and T_H2 antiinflammatory cytokines. The cytokine source(s) that initiate the imbalances are unknown. In this study, , CD4, and CD8 T cell receptor-positive (TCR+) cells were isolated from the blood of 26 definitive relapsing-remitting multiple sclerosis patients prior to interferon -1a (IFN1a) therapy and following 8–10 weeks of this therapy. The bioactivities of interferon (IFN), interleukin 10 (IL10), and interleukin 12 (IL12) were determined. The concentrations of IFN, IL10, and IL12 from each cell type did not change significantly with IFN1a treatment. The IL10 secreted by TCR+ cells strongly correlated with the IL12 secreted by the same TCR+ cells, supporting the paradigm. Furthermore, IFN1a therapy decreased the TCR+ cell secretion of T_H1 cytokines after 8–10 weeks of therapy.     

Regional administration of oncolytic Echovirus 1 as a novel therapy for the peritoneal dissemination of gastric cancer

The dissemination of malignant gastric cells to the peritoneum occurs frequently, usually as an early event in disease, and results in poor patient prognosis. Surgery and chemotherapy offer limited therapeutic success. The low-pathogenic human enterovirus, Echovirus 1 (EV1), is an oncolytic virus that selectively targets and destroys malignant prostate and ovarian cancer xenografts in vivo. Lytic EV1 infection requires the cell surface expression of α₂β₁, an integrin involved in the dissemination of gastric cancer cells to the peritoneum. Herein, we evaluated the capacity of EV1 for anti-neoplastic cell action in gastric peritoneal carcinomatosis. Flow cytometric analysis demonstrated that α₂β₁ was abundantly surface expressed on a panel of gastric cancer cell lines, rendering the majority of lines highly susceptible to in vitro lytic EV1 infection and supportive of efficient viral progeny production. A bioluminescent MKN-45-Luc SCID mouse model of peritoneal dissemination was developed to allow real-time non-invasive monitoring of peritoneal tumor burden. Employing this mouse model, we demonstrated a therapeutic dose-response for escalating oncolytic EV1 doses. Taken together, these results emphasize the exciting potential for EV1 as a single or adjunct therapy for the control of the peritoneal dissemination of gastric cancer.