The Expression And Significance Of Heparanase And Basic Fibroblast Growth Factor Protein In Gastric Carcinoma

Background and Objective Gastric cancer is one of the most common malignant neoplasms in China and its incidence is gradually increasing in recent years. Studies have showed that it is the leading cause of cancer death. The clinical outcome for gastric cancer patients is still very poor with a 5-year survival rate of only 20 % in all stages and only 40 % of the patients respond to surgical intervention. The main reason for death is invasion and metastasis of tumor.Tumor cell invasion and metastasis is the hallmark of malignant disease and the greatest impediment to cancer cure. Two essential processes required for metastasis are neoangiogenesis and tumor cell penetration through the barrier formed by the basement membrane (BM) and extracellular matrix (ECM). The barrier is mainly composed of structural proteins and glycosaminoglycans. The former mainly includes collagen IV , laminin and fibronectin, whereas the latter chiefly consists of heparan sulfate proglycans (HSPGs) which is formed by a core protein and several covalent-binding heparan sulfate (HS) side chains. HSPGs are ubiquitous macromolecules associated with the cell surface and ECM of a wide range of cells. HSPGs contribute to the structural integrity, selfassembly and insolubility of the ECM and basement membrane. Furthermore, numerous enzymes, growth factors and cytokines are sequestered by HSPGs on the cell surface and ECM.Heparanase (Hpa) is an endo-β-glucuronidase that cleaves HS at specific intra-chain sites and releases HS-bound biological active factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) . So it can play a key role in promoting tumor cell invasion and metastasis. bFGF is a kind of peptide which has several biological founctions and is overexpressed in many malignant tumors. bFGF can stimulate the proliferation, invasion, metastasis ofneoplastic cells . bFGF is also a potent angiogenic growth factor. bFGF exerts its biological effects mainly through the high affinity receptors on plasms membrane (FGFR) . HSPGs , which is the low affinity receptor of bFGF, is essential for bFGF singnal transduction. The activity of bFGF is stringently controlled because it can be inactive in normal tissues and becomes activated on tissue injury, inflammation, and tumor invasion. Hpa enzyme possesses the ability to activate bFGF through structural modulation of the cell surface H-S proteoglycan. Accordingly, Hpa and bFGF could play complementary biological activity in tumor angiogenesis and invasion. To our knowledge, expression of Hpa and its biological role in connection with bFGF expression in gastric carcinoma have not been evaluated so far. By observing the expression of Hpa and bFGF, we tried to find out whether both bFGF and Hpa were directly correlated to the degree of tumor invasiveness or not, whether the coexpression of Hpa and bFGF enhances the tumor invasiveness, whether both bFGF and Hpa were directly correlated to angiogenesis, and whether the coexpression of Hpa and bFGF enhances the tumor angiogenesis in gastric carcinoma.Methods Immunohistochemical SABC method was used to examine microvessel density(MVD) and the expression of Hpa and bFGF in 60 cases of primary gastric carcinoma and 15 normal gastric mucosa. We investigated the relationships between the expression of Hpa and bFGF and the clinicopathologic parameters and MVD. We also investigated there mutual relationship in the influence on tumor invasiveness and angiogenesis. All the dates were analyzed by SPSS 13.0 statistical package, the count information calculated the positive rate, enumerationdate expressed by standard deviation [3c ±s]. The comparison of positive rates uses the Chi-square or Fisher, the mean of two groups uses the t-test. The relation of two variable are analyzed by the correlation analysis. The level of significant difference is a=0.05.Results 1. Expression of Hpa: (1) Hpa expression was located in both the cytoplasm and the cytoplasmic membrane of the tumor cells. The most intensely stained region was the invasion front of tumors. Hpa was found mild to intense expression in vascular endothelial cells, macrophages, neutrophils and smooth muscle cells in stromal tissue. (2) 0 % (0 / 15 ) normal mucosa and 56.7 % (34 / 60) gastric carcinoma specimens showed Hpa positive stained. In gastric carcinoma specimens, the intensity of Hpa expression was remarkably increased compared with matchednormal mucosa specimens (p<0.05). (3) In 60cases cancer tissues, compared with without invasion serosal stratum group, the Hpa protein expression in invasion serosal stratum group increased significantly (P < 0.05). Tumors with lymph node metastases had more Hpa protein than those without metastases (P <0.05). According to clinico-pathological stage,the gastric carcinoma samples were divided into I, II, IH,andIV stage. Comprising the Hpa expression between I +11 and III+IV stage, the difference was significant(P <0.05) .Besides, the Hpa expression had no relation to the patients' age, sex, tumor location and differentiation(P>0.05). (4) In Hpa expression specimens, the intensity of MVD was remarkably increased compared with negative expression specimens (P <0.05).2. Expression of bFGF : (1) The positive staining of bFGF was mainly located in cytoplasm. Interstitium and normal gastric epithelia were sometimes positive with the antibody, but this staining was never as intense as that seen in tumors. (2) 61.7 percent (37of 60) of cases had expression of bFGF in the tumor cells, and in 26.7 % of cases (4 of 15) of the normal mucosa it were present. There was a significant positive correlation between gastric carcinoma specimens and normal mucosa specimens (P < 0. 05). (3) In 60cases cancer tissues, compared with without invasion serosal stratum group, the bFGF protein expression in invasion serosal stratum group increased significantly (P < 0.05). Tumors with lymph node metastases had more bFGF expression than those without metastases(P <0.05). According to clinico-pathological stage, comprising the bFGF expression between I + II and III + IV stage, the difference was significant(P <0.05). Besides, the bFGF expression had no relation to the patients' age, sex, tumor location and differentiation(P>0.05). (4) In bFGF expression specimens, the intensity of MVD was remarkably increased compared with negative expression specimens (P <0.05).3. Correlation among expression of Hpa and bFGF protein in gastric carcinoma: There was a significant correlation between the expression of Hpa and bFGF(P <0.05). Co-expression of the tow proteins had a more significant relationship with depth of invasion, lymph node metastasis, TNM stages and MVD. Conclusions1. There were overexpression of Hpa and bFGF protein in gastric carcinoma.2. Hpa and bFGF expression was significantly correlated with depth of invasion, lymph node metastasis, TNM stages and MVD in gastric carcinoma.3. Hpa and bFGF expression was significantly correlated with the MVD in gastric carcinoma.4. The agreement between Hpa and bFGF expression was significant, and the co-expression of the tow proteins was significantly correlated with depth of invasion, lymph node metastasis, TNM stages and MVD in gastric carcinoma.5. To detect the expression of Hpa and bFGF expression will faciliate the gastric carcinoma severity estimation and its prognose.