Expression Of Endostatin, BFGF And Their Relation With Stromal Angiogenesis In Human Gastric Carcinoma

Background and objective:Gastric carcinoma(GS) is one of the most common malignant neoplasms in the digestive system. Studies have showed that it is the leading cause of cancer death. The main reason for death in patients with GS is invasion and metastasis of tumor. What the researchers are more interested in is how to diagnose GS in early stage and to further investigate the mechanisms of invasion and metastasis.The growth and metastasis of solid tumors depends on angiogenesis. As an important component of tumor ecosystem, angiogenesis can influence the biologic behaviors of tumors by interacting with tumor cells. Microvessel density(MVD) is a quantitative measure of angiogenesis and has been shown to be an important parameter of various malignant tumors. Basic and clinical researches in recent years have shown that neovascularization is the key step in carcinogenesis as well as in tumou growth, invasion and metastasis. Angiogenesis is the key step in tumors proliferation and metastasis, which depends on the net balance between endogenous stimulators and inhibitors. It is confirmed that there is a persistent and uncontroled angiogenesis in tumor development. Angiogenesis not only provides tumors with nutrition but also with metastic channels.Tumor angiogenesis is regulated by various kinds of factors, basic fibroblast growth factor (bFGF )is fundenmental for its close relation with angiogenesis. bFGF exerts its biological effects mainly through the high affinity receptors on plasmsmembrane(FGFR) . HSPG (heparin sulfate proteoglycans) ,which is the low affinity receptor of bFGF, is essential for bFGF singnal transduction. bFGF promotes cell proliferation, induces angiogenesis and correlates with tumor cells' differentiation, growth and metastasis.Tumor angiogenesis is regulated by various stimulators and inhibitors. Es (endostatin) has attracted more attention for its perfect effects on anti-angiogenesis in vitro and in animal tumor models for years. The mechanism of its anti-angiogenesis yet dosen't illuminated. Crystal structure showed that on the surface of endostatin, there was a motif which consisted of 11 arginines.The motif was aslo considered as the endostatins pontential binding site with heparine. Es exerts its anti-angiogenesis effects through competing with bFGF for the heparine binding site.Researshers have done more on the pharmic effects of endostatin in the past years, but as its expression in carcinomatous tissues and its effects on the regulation of tumor angiogenesis are concered, the data are rare.In order to investigate the effects of growth factors and angiogenesis on the development of gastric carcinoma, immunohistochemical SP ( Streptavidin peroxidase) method was used to examine the expression of Bfgf,endostatin and CD34.Materials and Methods: 1. 65 surgically resected gastric carcinoma samples and 20 normal gastric mucosa were collected. All thd tissues were fixed in 10% neutral formalin and embedded in paraffin. 2. SP immunostaining technique was used to examine the expression of bFGF, endostatin and CD34 in normal gastric mucosa and gastric carcinoma. 3. The data were analysized by software SPSS 10.0, chi-square test was used to compare difference between groups; as for the CD34 concerned, t-test or analysis of variance was used according to the groups, a =0.05 was considered as statistically significant value. Results:1. The result of bFGF expression: (DThe positive staining of bFGF was mainly located in cytoplasm and partly in nucleus. (2)The expression of bFGF in normal mucosa was weak and the positive rates of bFGF was 15 % (3/20 ) . The positive rateof bFGF was 49.2% (32/65 )in gastric carcinoma and the positive rate in the latter was significantly higher than that in normal mucosas (P<0.01) . (3)The positive rate of bFGF was 65.9%(27/4l)in the group with serosa infiltration and higher than that in the group without serosa infiltration (20.8%, 5/24, PO.01); The positive rate of bFGF was 60.5 % in the group with lymph node metastasis and higher than that in the group without lymph node metastasis(33.3%, P<0.05). bFGF also closely correlated with TNM stages. The positive rate of bFGF in III and IV stages was higher than that in I and II stages (68.6%, 24/35Vs26.7%, 8/30, P<0.01 ) .No correlation was found between the bFGF expression and histologic grade,patients'ages and sex.2. The result of endostatin expression: (DThe positive staining of endostatin was mainly located in cytoplasm and partly in nucleus. (2)The expression of bFGF in normal mucosa was weak and the positive rate of endostatin was 20% (4/20) . The positive rate of endostatin was 61.5% (40/65) in gastric carcinoma and the positive rate in the latter was significantly higher than that in normal mucosas(P<0.01). (3)The positive rate of endostatin was 51.2%(21/41)in the group with serosa infiltration and lower than that in the group without serosa infiltration (79.2 %, 19/24, PO.05 ); The positive rate of endostatin was 50.0% in the group with lymph node metastasis and lower than that in the group without lymph node metastasis(77.8%, P<0.05). endostatin also closely correlated with TNM stages. The positive rate of endostatin in III and IV stages was lower than that in I and II stages (48.6%, 17/35Vs26.7%, 23/30, P<0.01 ) .No correlation was found between the endostatin expression and histologic grade, patientsages and sex.3. The result of MVD expression: (DCD34 related antigen was observed in the cytoplasm of endothelial cells. (2)MVD was 25.50± 10.75 in the gastric carcinoma group and was 9.70±4.37 in the normal mucosa group (P<0.01). (3)MVD in the group with serosa infiltration was 28.33±10.89 and higher than that in the group without serosa infiltration (20.66±8.76,P<0.01); MVD in the group with lymph node metastasis was 28.92±11.24 and higher that in the group without lymph node metastasis(20.70±7.99,P<0.01); As to the TNM stages concerned, MVD in the group of III and IV stages was 30.21±10.55 and higher than that in the group of I and IIstages (20.01±8.16,P<0.01). No correlation was found between the MVD expression and histologic grade, patients'ages and sex.4. The association between bFGF expression and MVD in gastric carcinoma: The MVD in the bFGF-positive group and in the bFGF-negative group were 30.33±10.05 and 20.82±9.35 respectively,and the difference between them was significant(PO.01) .5. The association between endostatin expression and MVD in gastric carcinoma: The MVD in the endostatin-positive group and in the endostatin -negative group was 22.80±10.82 and 29.84±9.28 respectively,and the difference between them was significant (PO.01) .6.MVD in the En-/bFGF+ group was 31.99±10.04 and higher than that in theEn+/bFGF-group(19.40±9.96,P<0.01).7. The correlation berween bFGF expression and endostatin expression in gastriccarcinoma:There were 15 cases in the gastric carcinoma group where the expressionof bFGF and endostatin was positive simultaneously. The simultaneously negativewas 8 cases. Spearman correlation showed that bFGF had a negative correlation withendostatin in gastric carcinoma(rs=-0.297).Conclusions:1. The positive expression of bFGF in gastric carcinoma was significantly higher than that in normal mucosa, the overexpression of bFGF was correlated with TNM stages, infiltration depth and whether there was lymph node metastasis. The overexpression of bFGF might participate in the process of gastric carcinogenesis and the progression of gastric carcinoma.2. Reduced positive expression of endostatin was correlated with TNM stages, infiltration depth and whether there was lymph node metastasis. It suggested that reduced expression of endostatin might participate in the process of gastric carcinogenesis and the progression of gastric carcinoma as well as the enhancement of the tumor invasive ability.3. Angiogenesis plays an important role in the progression of gastric carcinoma.4. bFGF and endostatin are both important regulators in the process of angiogenesisin gastric carcinoma.5. The expression of bFGF was negatively correlated with the expression of endostatin in gastric carcinoma. It suggested that there was a regularly altertion between promoters and inhibitors in gastric carcinoma angiogenesis.6. To detect the expression of bFGF, endostatin and MVD will faciliate the gastric carcinoma severity estimation and its prognose.