Angiogenesis In Gastric Cancer Research Articles

Inhibition of osteopontin would suppress angiogenesis in gastric cancer

Osteopontin (OPN) plays an important role in tumorigenesis, tumor invasion, and metastasis in many types of cancers, including gastric cancer. Recently, much interest has been focused on the role of OPN in tumor angiogenesis. Our previous studies have shown that OPN is overexpressed, and associated with mean microvessel density in, the tissue samples of patients with gastric cancer. In the present study, we aimed to further determine and provide evidence for the role of OPN in gastric-cancer-associated angiogenesis by diminishing OPN expression in gastric cancer cells using the small interference RNA method, and then evaluate the effects of OPN on gastric cancer-associated angiogenesis by in vivo and in vitro assays. Our results revealed that reduced OPN production by gastric cancer cells would reduce the proliferation, migration, and tube formation of human umbilical vein endothelial cells, and lead to a lower microvessel density, i.e., angiogenesis, in transplanted tumors of mice. These data confirm the positive role of OPN in gastric-cancer-associated angiogenesis.

Effect of celecoxib on E-cadherin, VEGF, microvessel density and apoptosis in gastric cancer

Cyclooxygenase-2 (COX-2) plays a crucial role in the development and invasion of gastric cancer. COX-2 inhibitors have been shown to be chemopreventive against gastrointestinal cancers. In vitro studies have suggested that the mechanisms may be related to induction of apoptosis and inhibition of angiogenesis. COX-2 may also have impact on E-cadherin. In our study we investigate the effect of Celecoxib on expression of E-cadherin and serum soluble E-cadherin, as well as on apoptosis and angiogenesis in patients with gastric cancer. Fifty nine gastric cancer patients were randomly divided into 2 groups: Surgery group (n=22), in which patients underwent surgical resection after diagnosis, and Celecoxib + Surgery group (n=37), in which patients received oral Celecoxib 200 mg twice daily for 7 days before curative resection. Twenty healthy subjects (Healthy controls) were recruited as normal controls. After curative resection, COX-2, E-cadherin, VEGF, and MVD were detected by immunohistochemistry. Serum soluble E-cadherin was quantitatively measured using a commercially available enzyme-linked immunosorbent assay kit. Apoptosis was determined by TUNEL assay. Significantly decreased expression of COX-2, increased E-cadherin and apoptosis, decreased VEGF and MVD were observed in gastric cancer tissues from patients receiving Celecoxib compared to Surgery group. Compared to Healthy controls, the serum soluble E-cadherin levels were higher in gastric cancer patients which were decreased by Celecoxib. This in vivo study demonstrated that Celecoxib induces apoptosis and inhibit angiogenesis of gastric cancer. Its impact on E-cadherin may suggest that this agent may suppress the invasion of advanced gastric cancer.

Angiogenesis in gastric cancer: Importance of the thymidine phosphorylase expression of cancer cells as an angiogenic factor

Thymidine phosphorylase (TP) has been reported to stimulate angiogenesis in a variety of human malignancies. We investigated TP expression and its association with angiogenesis in 73 cases of resected gastric cancer. In addition, we compared the expression of the other angiogenesis related factors (VEGF, eNOS and p53) with that of TP with respect to angiogenesis. TP expression was not detected in most of the non-tumoral glandular epithelial cells except for 5 cases. TP expression of the cancer cells and the stroma was assessed separately. The stromal TP expression was not associated with the TP expression of the cancer cells. The mean percent of TP reactive cancer cells was 18.36+/-2.61 (median, 10.00; range, 0-90) and cases showing a percentage higher than the mean were considered as bearing high reactivity. The mean microvessel score assessed was 90.44+/-3.69 (median, 86; range, 31-174). The TP expression of cancer cells was strongly associated with microvessel density (p=0.030), but the stromal TP expression was not. The microvessel density of the tumor showed strong correlation with VEGF expression (p<0.001), but a marginally significant association with eNOS (p=0.055). On the contrary, there was no association with p53 expression and microvessel density of the tumor. No significant correlation was detected between lymph node metastasis and tumoral or stromal TP expression or VEGF/TP coexpression. In gastric cancer, TP expression of the cancer cells, not stromal cells may play an important role in tumor growth by microvessel formation.

RUNX3 Inhibits the Expression of Vascular Endothelial Growth Factor and Reduces the Angiogenesis, Growth, and Metastasis of Human Gastric Cancer

Recent studies indicated that RUNX3 exhibits potent antitumor activity. However, the underlying molecular mechanisms of this activity remain unclear. In the present study, we used a gastric cancer model to determine the effect of RUNX3 expression on tumor angiogenesis. The effects of increased RUNX3 expression on vascular endothelial growth factor (VEGF) expression in and angiogenic potential of human gastric cancer cells were determined in vitro and in animal models. RUNX3 and VEGF expression was determined in 120 human gastric cancer specimens and their relationship was analyzed. RUNX3 gene transfer suppressed VEGF expression in human gastric cancer cells. Down-regulation of VEGF expression correlated with a significantly impaired angiogenic potential of human gastric cancer cells. Furthermore, RUNX3 restoration inhibited tumor growth and metastasis in animal models, which was consistent with inhibition of angiogenesis as determined by evaluating VEGF expression and tumor microvessel formation. In gastric cancer specimens, loss or decrease in RUNX3 expression inversely associated with increased VEGF expression and elevated microvessel formation. Our clinical and experimental data provide a novel molecular mechanism for the antitumor activity of RUNX3 and may help design effective therapy targeting RUNX3 pathway to control gastric cancer growth and metastasis.

Expression of survivin in gastric cancer and its relationship with tumor angiogenesis

Survivin, a member of inhibitors of apoptosis, has been found in various human cancers. Its expression is associated with tumor progression and adverse outcome. Angiogenesis is an essential process for the primary tumor to grow and invade the adjacent normal structures. Angiogenic factors such as vascular endothelial growth factor induce survivin expression in endothelial cells. The current study was designed to investigate the possible role of survivin and vascular endothelial growth factor status for angiogenesis in human gastric cancer. In this study, we conducted an immunohistochemical investigation of survivin and vascular endothelial growth factor expression in 106 tissue samples obtained from gastric cancer patients undergoing surgical treatment. To assess tumor angiogenesis, microvessel density was counted by staining endothelial cells immunohistochemically using anti-CD34 monoclonal antibody. The positive expression of survivin and vascular endothelial growth factor in gastric cancer tissues was demonstrated in 50.0 and 69.8% of cases, respectively. The expression of survivin did not associate with vascular endothelial growth factor expression. Expression of survivin was significantly associated with tumor size, depth of invasion, lymph node metastasis, tumor stage and poor survival (P=0.011, 0.004, 0.020, 0.002, 0.046, respectively). High microvessel density was significantly associated with lymph node metastasis and poor survival (P=0.006 and 0.017, respectively). The mean microvessel density value of survivin positive tumors was 87.4+/-34.4 and significantly higher than that of survivin negative tumors (P=0.016). The mean microvessel density value of vascular endothelial growth factor positive tumors was 98.7+/-37.0 and significantly higher than that of vascular endothelial growth factor negative tumors (P=0.001). A combined analysis of survivin and vascular endothelial growth factor status showed that the mean microvessel density value of both positive tumors was 103.7+/-33.1 and significantly higher than that of both negative tumors (P<0.001). These results suggest that survivin may play an important role in carcinogenesis by stimulating tumor angiogenesis in human gastric cancer.

Antisense angiopoietin-1 inhibits tumorigenesis and angiogenesis of gastric cancer

To investigate the effect of angiopoietin-1 (Ang-1) on biological behaviors in vitro and tumorigenesis and angiogenesis in vitro of human gastric cancer cells. Human full-length Ang-1 gene was cloned from human placental tissues by RT-PCR method. Recombinant human Ang-1 antisense eukaryotic expression vector was constructed by directional cloning, and transfected by lipofectin method into human gastric cancer line SGC7901 with high Ang-1 expression level. Inhibition efficiency was confirmed by semi- quantitative PCR and Western blot method. Cell growth curve and cell cycle were observed with MTT assays and flow cytometry, respectively. Nude mice tumorigenicity test was employed to compare in vitro tumorigenesis of cells with Ang-1 suppression. Microvessel density (MVD) of implanted tumor tissues was analyzed by immunohistochemistry for factor VIII staining. Full-length Ang-1 gene was successfully cloned and stable transfectants were established, namely 7Ang1- for antisenseìand 7901P for empty vector transfected. 7Ang1- cells showed down-regulated Ang-1 expression, while its in vitro proliferation and cell cycle distribution were not significantly changed. In contrast, xenograft of 7Ang1- cells in nude mice had lower volume and weight than those of 7901P after 30 days' implantation (P<0.01, 293.00+/-95.54 mg vs. 624.00+/-77.78 mg) accompanied with less vessel formation with MVD 6.00+/-1.73 compared to 7901P group 8.44+/-1.33 (P<0.01). Ang-1 may play an important role in tumorigenesis and angiogenesis of gastric cancer, and targeting its expression may be beneficial for the therapy of gastric cancer.

Expression of inducible nitric oxide synthase and cyclooxygenase-2 in angiogenesis and clinical outcome of human gastric cancer

It has been recognized that inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) produce important endogenous factors of human tumors such as nitric oxide (NO) and prostaglandins, which is involved in the process of carcinogenesis and tumor progression. This study aimed to evaluate the association of clinicopathologic factors, microvessel density, and patient survival with the expression of iNOS and COX-2 in patients with gastric adenocarcinoma. Seventy-nine specimens, resected from patients with gastric adenocarcinoma, were investigated by immunohistochemical stain against iNOS and COX-2. Microvessels were stained using anti-CD34 antibody and counted as microvessel density. Positive iNOS and COX-2 expressions were significantly correlated with microvessel density by multivariate analysis, respectively (P = 0.0127 vs. P = 0.0214). There was significant difference among the four groups (both iNOS and COX-2 positive, iNOS positive only, COX-2 positive only, and both negative) in serosal invasion (P = 0.038), lymph node metastasis (P = 0.038), Helicobacter pylori infection (P = 0.025), vascular invasion (P = 0.035), and microvessel density (P = 0.019). In patients with gastric cancer that co-expressed iNOS and COX-2, prognosis was significantly poorer than in those that expressed either iNOS or COX-2, or did not express both of them (P = 0.01738). The Cox proportional hazard regression analysis indicated that iNOS expression, vascular invasion, serosal invasion, and microvessel density are independent prognostic factors for patients with gastric cancer. iNOS and COX-2 expression of gastric cancer are related to tumor angiogenesis, tumor progression, and patient survival in human gastric cancer.

Alphastatin downregulates vascular endothelial cells sphingosine kinase activity and suppresses tumor growth in nude mice bearing human gastric cancer xenografts

To investigate whether alphastatin could inhibit human gastric cancer growth and furthermore whether sphingosine kinase (SPK) activity is involved in this process. Using migration assay, MTT assay and Matrigel assay, the effect of alphastatin on vascular endothelial cells (ECs) was evaluated in vitro. SPK and endothelial differentiation gene (EDG)-1, -3, -5 mRNAs were detected by reverse transcription-polymerase chain reaction (RT-PCR). SPK activity assay was used to evaluate the effect of alphastatin on ECs. Matrigel plug assay in nude mice was used to investigate the effect of alphastatin on angiogenesis in vivo. Female nude mice were subcutaneously implanted with human gastric cancer cells (BGC823) for the tumor xenografts studies. Micro vessel density was analyzed in Factor VIII-stained tumor sections by the immunohistochemical SP method. In vitro, alphastatin inhibited the migration and tube formation of ECs, but had no effect on proliferation of ECs. RT-PCR analysis demonstrated that ECs expressed SPK and EDG-1, -3, -5 mRNAs. In vivo, alphastatin sufficiently suppressed neovascularization of the tumor in the nude mice. Daily administration of alphastatin produced significant tumor growth suppression. Immunohistochemical studies of tumor tissues revealed decreased micro vessel density in alphastatin-treated animals as compared with controls. Downregulating ECs SPK activity may be one of the mechanisms that alphastatin inhibits gastric cancer angiogenesis. Alphastatin might be a useful and relatively nontoxic adjuvant therapy in the treatment of gastric cancer.

Expression of chymase‐positive cells in gastric cancer and its correlation with the angiogenesis

Chymase is expressed in mast cells and induces angiogenesis via activation of angiotensin II and matrix metalloproteinase-9. However, it has been unclear whether chymase is involved in the pathophysiology of angiogenesis in gastric cancer. To clarify the contribution of chymase to angiogenesis in gastric cancer, we assessed the relationship between chymase-positive cells and tumor angiogenesis. We evaluated chymase-positive cells and microvessels using anti-human chymase and anti-CD34 antibodies in 168 cases of gastric cancer, respectively. Chymase-positive cells in gastric tumor region were significantly higher than the cells in normal region. The number of chymase-positive cells in the undifferentiated type of gastric tumor region was significantly higher than the one in the differentiated type. Specimens from patients with advanced histological stages of disease had more chymase-positive cells than those with early-stage disease. There was a significant positive correlation between chymase-positive cells and microvessels in gastric cancer specimens. Postoperative survival curves revealed that patients with a high number of chymase-positive cells had a poor prognosis. These results suggest that accumulation of chymase-positive cells in gastric cancer may lead to an increase of tumor angiogenesis, and may contribute to tumor growth and progression.

Correlation between expression of matrix metalloproteinase-2, matrix metalloproteinase-9 and angiogenesis in gastric cancer

Objective: To investigate the relationship between matrix metalloproteinase-2 (MMP-2), MMP-9 as well as microvessel density (MVD) and their clinicopathological features in gastric cancer. Methods: The expression of MMP-2, MMP-9 and MVD were detected by immunohistochemistry SP method on 65 cases of gastric cancer tissue and 32 adjacent gastric mucosa. Results: The positive expression of MMP-2, MMP-9 and MVD in cancer group were significantly higher than those of adjacent mucosa group (P<0.01). The positive expression of MM P-2 and MMP-9 had closely correlation with clinical features of lymphatic metastasis, pathological type and stages (P<0.05), and the high level of CD 34 had correlation with metastasis and stages (P<0.01). The positive expression of MMP-2 and MMP-9 showed significant correlation with the level of MVD. Prognosis was mostly affected by lymphatic metastasis and stages of clinical features. The low cum survival rate was showed in the groups of positive expression of MMP-2, MMP-9 and high level of MVD. Conclusion: MMP-2, MMP-9 and MVD play an important role in metastases, invasion and prognosis of gastric cancer, which is a valuable maker to evaluate the prognosis.

Interleukin‐10 expression significantly correlates with minor CD8+ T‐cell infiltration and high microvessel density in patients with gastric cancer

We aimed to investigate the relationships between interleukin-10 (IL-10) expression and both the clinicopathological findings and prognoses in patients with gastric cancer and to compare IL-10 expression with microvessel (MV) density and CD8+ T lymphocyte infiltration to evaluate its effects on angiogenesis and immune responses in gastric cancer. IL-10 expression was determined in gastric cancer patients by reverse transcription-polymerase chain reaction (RT-PCR) or immunohistochemical procedures. Two of 7 normal gastric tissues showed IL-10 mRNA expression, while its expressions were confirmed in all advanced gastric carcinoma tissues examined (n=11) by RT-PCR. Immunohistochemical staining demonstrated that IL-10 expression was detected in 52 (47.7%) of 109 cases. There was a close correlation between IL-10 expression and MV density. IL-10 expression inversely correlated with CD8+ T-lymphocyte infiltration. The prognoses of patients whose tumors expressed IL-10 were significantly worse than those of patients whose tumors did not express IL-10. Multivariate analysis indicated IL-10 expression was an independent prognostic factor. IL-10 might be associated with tumor progression by stimulating angiogenesis and suppressing immune responses in gastric cancer.

Nicotine Induces Cyclooxygenase-2 and Vascular Endothelial Growth Factor Receptor-2 in Association with Tumor-Associated Invasion and Angiogenesis in Gastric Cancer

Blockade of angiogenesis is a promising strategy to suppress tumor growth, invasion, and metastasis. Vascular endothelial growth factor (VEGF), which binds to tyrosine kinase receptors [VEGF receptors (VEGFR) 1 and 2], is the mediator of angiogenesis and mitogen for endothelial cells. Cyclooxygenase-2 (COX-2) plays an important role in the promoting action of nicotine on gastric cancer growth. However, the action of nicotine and the relationship between COX-2 and VEGF/VEGFR system in tumorigenesis remain undefined. In this study, the effects of nicotine in tumor angiogenesis, invasiveness, and metastasis were studied with sponge implantation and Matrigel membrane models. Nicotine (200 microg/mL) stimulated gastric cancer cell proliferation, which was blocked by SC-236 (a highly selective COX-2 inhibitor) and CBO-P11 (a VEGFR inhibitor). This was associated with decreased VEGF levels as well as VEGFR-2 but not VEGFR-1 expression. Topical injection of nicotine enhanced tumor-associated vascularization, with a concomitant increase in VEGF levels in sponge implants. Again, application of SC-236 (2 mg/kg) and CBO-P11 (0.4 mg/kg) partially attenuated vascularization by approximately 30%. Furthermore, nicotine enhanced tumor cell invasion through the Matrigel membrane by 4-fold and promoted migration of human umbilical vein endothelial cells in a cocultured system with gastric cancer cells. The activity of matrix metalloproteinases 2 and 9 and protein expressions of plasminogen activators (urokinase-type plasminogen activator and its receptor), which are the indicators of invasion and migration processes, were increased by nicotine but blocked by COX-2 and VEGFR inhibitors. Taken together, our results reveal that the promoting action of nicotine on angiogenesis, tumor invasion, and metastasis is COX-2/VEGF/VEGFR dependent.

Cyclooxygenase-2 expression is associated with VEGF-C and lymph node metastases in gastric cancer patients

Previous studies have suggested that cyclooxygenase-2 (COX-2) over-expression is associated with angiogenesis in gastric cancer. However, the relationship between COX-2 and lymphangiogenesis is still unclear. The aim of this study was to determine the relationship between COX-2 expression and lymphangiogenic factor, vascular endothelial growth factor-C (VEGF-C), in human gastric cancer, as well as to correlate with clinicopathological parameters. Sixty-three gastric cancer patients underwent radical gastrectomy (D2 or D3) were enrolled in this study. The expression of COX-2 and VEGF-C were detected by immunohistochemistry, and the small lymphatic vessels were immunohistochemically stained by LYVE-1 antibody. The association between COX-2 and VEGF-C expressions and clinicopathological parameters (such as gender, tumor location, lymph node status and Lauren classification) were determined. VEGF-C over-expression was observed in 33 of 63 patients (52%), while COX-2 over-expression occurred in 42 of 63 tumor samples (67%). Presence of microlymphatic vessels with LYVE-1 staining was found in 35 cases. COX-2 over-expression was highly correlated with VEGF-C over-expression (P = 0.032), microlymphatic vessels (P = 0.002) as well as presence of metastatic lymph nodes (P = 0.007). However, no significant correlation was found between COX-2 expression and other clinicopathological parameters. Our data suggest that COX-2 expression is associated with lymphangiogenesis and lymph node metastasis in human gastric carcinoma. This raises the possibility that COX-2-mediated VEGF-C over-expression might promote lymph node metastasis via lymphangiogenesis pathway in patients with gastric cancer.

Cyclooxygenase-2 inhibitors suppress angiogenesis and growth of gastric cancer xenografts

Many researches have confirmed the tumor-prophylactic effects of cyclooxygenase-2 (COX-2) inhibitors. We previously observed their anti-cancer effects in vivo in nude mice and found that sulindac, a traditional non-steroidal anti-inflammatory drug (NSAID), and celecoxib, a selective COX-2 inhibitor, depressed the growth of SGC7901 xenografts via altering cell kinetics. Then we deeply studied the relationship between the two drugs and angiogenesis in gastric cancer. The results showed both sulindac and celecoxib decreased the micro-vessel density (MVD), which was labeled by either CD34 or VWF staining, within xenografts. Expression of both vascular endothelial growth factor (VEGF) and FGF-1 was suppressed. In addition, a positive correlation between MVD and the volume of SGC7901 xenografts was found. The effect of selective COX-2 inhibitor was stronger than non-special one despite of the insignificant difference. These results demonstrate that COX-2 plays an important role in angiogenesis of cancer. Apart from interfering cell kinetics, decreasing the expression of angiogenic factors and then inhibiting tumor angiogenesis could also be one of the mechanisms that COX-2 inhibitors suppress the growth of gastric cancer. These findings offer another theory basis for the future clinical application of NSAIDs against cancer.

Relationship between cyclooxygenase- 2 expression and angiogenesis in patients with gastric cancer

To investigate COX-2 expression in patients with gastric cancer and its relationship with angiogenesis and clinicopathologic features of gastric cancer. COX-2 expression and CD34-stained microvessel density (MVD) were detected by immunohistochemical methods in specimens from 96 patients with gastric cancer. The correlations among COX-2 expression, MVD and clinicopathologic features were analyzed. The COX-2 positive rate and MVD in gastric cancer were significantly higher than those in the normal gastric mucosa (80.2% vs. 13.3%; 32.5+/- 8.3 vs. 13.1+/- 2.4, all P< 0.01). The COX-2 positive rate and MVD in the patients with stage III and IV were significantly higher (91.4% and 34.9+/- 8.7 respectively, P< 0.01), than that in the patients with stage I and II. The COX-2 positive rate and MVD in the cases with lymph node metastasis were 87.9% and (35.0+/- 8.5) respectively, higher than those in the cases without lymph node metastasis (P< 0.05). The Spearman rank correlation test showed a significant correlation between COX-2 expression and tumor MVD (r=0.311, P< 0.01). COX-2 plays an important role in gastric cancer angiogenesis. COX-2 and angiogenesis induced by COX-2 contribute to tumor invasion and lymph node metastasis.

Expression of endothelial nitric oxide synthase correlates with the angiogenic phenotype of and predicts poor prognosis in human gastric cancer

Angiogenesis is a critical aspect of cancer biology and is subject to regulation by multiple molecular pathways. We evaluated the expression of nitric oxide synthase (NOS) III and its relationship with the angiogenic phenotype and expression of the transcription factor Sp1, as well as their effect on survival in patients with gastric cancer. The NOS III expression level and tumor microvessel density (MVD) status were determined via immunohistochemistry, using archived tissue specimens from 86 resected gastric cancer cases; these findings were then correlated with Sp1 expression and clinicopathological features. NOS III protein expression was significantly higher in both primary tumors and lymph node metastases than in normal gastric mucosa. In primary tumors, NOS III expression correlated highly with Sp1 expression (P = 0.001) and MVD status (P = 0.001). Patients with strong Sp1 expression were more likely to have strong NOS III expression (15 times) and a high MVD (7 times) than were those with negative Sp1 expression. In univariate survival analyses, strong NOS III expression (P = 0.042), strong Sp1 expression (P = 0.007), and a high MVD (P = 0.036) were associated with worse survival. However, when patients' NOS III and Sp1 expression levels, MVD status, disease stage, completeness of resection, Lauren's classification, and age were entered in a Cox proportional hazards model, only strong NOS III (P = 0.019) and Sp1 expression (P = 0.029) and advanced disease stage (P = 0.006) were independently prognostic of poor survival. Our results indicated that the expression of NOS III, a potential downstream effector of Sp1, may play an important role in tumor angiogenesis and aggressiveness in gastric cancer.

Relationship between bFGF mRNA and MMP-9 mRNA expression in gastric carcinoma and their clinicopathological features as well as patients survival

To investigate the mRNA expression of bFGF and MMP-9 in gastric carcinomas and to find their correlation with tumor microvascular density (MVD), invasion, metastasis and patients survival. In situ hybridization and immunohistochemistry technique were used to test the expression of bFGF mRNA and MMP-9 mRNA and protein of CD34 in 105 specimens of gastric carcinoma. In situ hybridization revealed that the positive rates of bFGF mRNA and MMP-9 mRNA were 60.95 and 58.1%, respectively; The mean MVD (46.09 +/- 11.52, 43.75 +/- 13.41 piece/0.72 mm(2)) in tumors with bFGF mRNA and MMP-9 mRNA positive expression was significantly higher than that (29.41 +/- 12.47; 33.45 +/- 13.92 piece/0.72 mm(2)) in tumors with their negative expression, respectively; The positive expression rates of bFGF and MMP-9 mRNA were correlated to invasion depth (r(s) = 0.211, P = 0.031; r(s) = 0.335, P = 0.001, respectively), growing pattern (r(s) = 0.324, P = 0.001; r(s) = 0.267, P = 0.006, respectively), vessel invasion (r(s) = 0.579, P = 0.001; r(s) = 0.209, P = 0.032, respectively), lymph node metastasis (r(s) = 0.405, P = 0.001; r(s) = 0.343, P = 0.001, respectively) and distant metastasis (r(s) = 0.474, P = 0.001; r(s) = 0.468, P = 0.001, respectively), but not correlated to tumor type (r(s) = 0.134, P = 0.173; r(s) = 0.103, P = 0.145, respectively) and differentiation (r(s) = 0.096, P = 0.332; r(s) = 0.102, P = 0.298, respectively); And then, the mean MVD in tumors with infiltrating type, stage T(3)-T(4), vessel invasion, lymph node metastasis and distant metastasis was significantly higher than that in tumors with expanding type (t = 10.105, P = 0.001), stage T(1)-T(2) (t = 5.961, P = 0.001), non-vessel invasion (t = 7.394, P = 0.001), non-lymph node metastasis (t = 3.819, P = 0.01) and non-distant metastasis (r = 10.578, P = 0.001); There was a positive relationship between MVD and bFGF mRNA and MMP-9 mRNA (t = 3.207, P = 0.002; t = 7.035, P = 0.001), respectively; the mean survival time in cases with positive bFGF mRNA and MMP-9 mRNA and MVD value >/= 39.5 was significantly shorter than that in cases with their negative expression and MVD value < 39.5. bFGF and MMP-9 promote angiogenesis in gastric cancer. Test of the expression of bFGF and MMP-9 may act as an useful index to determine angiogenesis, invasion, metastasis and patients survival.

Anti-cancer effect of iNOS inhibitor and its correlation with angiogenesis in gastric cancer

To observe the anti-cancer effect of iNOS selective inhibitor (aminoguanidine, AG) and investigate the relationship between iNOS inhibitor and angiogenesis, infiltration or metastasis in MFC gastric cancer xenografts. Fifty athymic mice xenograft models were established by inoculating gastric cancer cell MFC subcutaneously. Twenty-four hours later, 0.9% sodium chloride solution, mitomycin, low dosage AG, high dosage AG, mitomycin and AG were administered by intraperitoneal injection respectively. Thus these mice were divided into five groups of 10 each randomly: control group, MMC group, AG(L) group, AG(H) group, MMC+AG(H) group. Two weeks later the mice were killed, and the tumor weight, inhibitory rate were evaluated. Greiss assay was used to detect the nitric oxide levels in plasma. HE and immunohistochemistry staining were used to examine microvessel density (MVD) and the expression of iNOS, VEGF, and PCNA. Apoptosis was detected by using TUNEL assay. The inhibitory rates in MMC+AG(H) group and AG(H) group were 52.9% and 47.1% respectively, which is significant statistically compared with that of control group (0). In treatment groups, the cell proliferation index (PI) was lower and apoptosis index was higher than those of control group. Microvessel density, iNOS, and VEGF in MMC+ AG(H) group were 8.8+/-2.6, 2.4+/-1.1, and 2.1+/-1.4 respectively, which is significant statistically compared with those of control group (68.3+/-10.6, 11.3+/-1.3, and 10.3+/-1.6). The NO level in plasma of MMC+ AGH and AG(H) group were 12.7+/-2.1 and 12.9+/-2.0 mumol/L. Compared with that of control group (46.6+/-2.3 mumol/L), the difference is statistically significant. AG has anticancer effect on gastric cancer, and it has positive synergistic effect with chemotherapeutic drugs. It may play important inhibitory roles in angiogenesis of gastric cancer. The anticancer effect of iNOS inhibitors may include inducing cell apoptosis, suppressing cell proliferation and reducing angiogenesis.

Inhibition of gastric cancer angiogenesis by vector-based RNA interference for Raf-1

Tumor angiogenesis plays an important role in the malignancy of solid tumors. A number of recent studies including our own have suggested that Raf-1 is involved in this process, and may be critical in regulating gene activation of several angiogenesis factors. To further define Raf-1 function in angiogenesis and to explore novel approaches to modulate angiogenesis, we employed the small interference RNA technique to knockdown gene expression of Raf-1 in gastric cancer cell line SGC7901 that expresses a high level of Raf-1. The protein level of Raf-1 in the SGC7901cells was decreased dramatically after transfection with a Raf-1 specific siRNA vector. Further study proved that, VEGF and HIF-1£\\, two angiogenesis promoting factors, were found to be downregulated. And we also find that Vector-based RNA interference for Raf-1 increases transfected gastric cell apoptosis and inhibits cellular proliferation. Our results suggest that Raf-1 may be involved in angiogenesis by controlling the expression of angiogenesis-related factors and provide a possible strategy for the treatment of tumor angiogenesis by targeting Raf-1.

ZD6474, a vascular endothelial growth factor receptor tyrosine kinase inhibitor with additional activity against epidermal growth factor receptor tyrosine kinase, inhibits orthotopic growth and angiogenesis of gastric cancer

Vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) have been strongly implicated in the growth and metastasis of gastric cancer. The purpose of this study was to examine the effects of ZD6474, an inhibitor of inhibitor of VEGF receptor (VEGFR) tyrosine kinase with additional activity against EGF receptor (EGFR), on tumor growth and angiogenesis in an orthotopic model of gastric cancer. In vitro, ZD6474 inhibited human umbilical vascular endothelial cell and TMK-1 human gastric tumor cell proliferation in a dose-dependent fashion. EGF-mediated activation of EGFR and Erk-1/2 was decreased in tumor cells after ZD6474 treatment. In addition, VEGF-mediated activation of VEGFR2 and Erk-1/2 was decreased in human umbilical vascular endothelial cells. TMK-1 human gastric adenocarcinoma cells were injected into the gastric wall of nude mice. ZD6474 therapy was initiated on day 10. Mice (n = 14 per group) were treated p.o. with (a) 1% Tween 80 (control), (b) 50 mg/kg/d ZD6474, or (c) 100 mg/kg/d ZD6474. Mice were sacrificed on day 33. Tumors from each group were stained for markers of blood vessels, pericytes, proliferation, and apoptosis. ZD6474 at both 50 and 100 mg/kg/d led to marked inhibition of tumor growth (P < 0.05). ZD6474 reduced tumor cell proliferation by 48% in the 50 mg/kg/d group and 65% in the 100 mg/kg/d group (P < 0.03) and increased tumor cell apoptosis (P < 0.001) in vivo. ZD6474 led to a 69% decrease in microvessel density in the 50 mg/kg/d group (P < 0.001) and a 62% decrease in the 100 mg/kg/d group (P < 0.001). Although microvessel density was decreased by ZD6474, the remaining vessels showed a relatively higher percentage of pericyte coverage (3-fold increase; P < 0.001), perhaps reflecting selective loss of uncovered vessels in the ZD6474 group. In conclusion, therapies such as ZD6474 that target two distinct aspects of tumor growth, angiogenesis and tumor cell proliferation, warrant further investigation.