The Expression Of COX-2 And VEGF-C In Gastric Cancer And The Correlation With Lymph Node Metastasis And Prognosis

IntroductionLymph node metastasis plays an important role and has a significant impact on recurrence and survival in patients with gastric cancer. However, the mechanism of lymph node metastasis remains unclear. It was reported that lymph node metastasis was correlated with intratumoral lymphangiogenesis in which vascular endothelial growth factor - C (VEGF - C) was a major regulating factor. Many studies indicated that expression of cyclooxygenase - 2 ( COX - 2) was correlated with occurrence and lymph node metastasis in many kinds of cancers including gastric cancer. In this study, we detected the expression of COX - 2 and VEGF - C and lymphatic vessel density ( LVD) using immunohistochemical SABC methods to investigate the relationship between them, as well as to correlate with clinicopathological parameters and survival in human gastric cancer.MethodsPatients: 51 gastric cancer cases underwent completely resected, which were enrolled from the first affiliated hospital, China Medical University ( CMU) , none of them underwent chemotherapeutics or actinotherapy before operation. All the cases included 37 male and 14 female with median age of 54.9 years, lymph node metastasis 36, the survival time ranged from 3 to 74 months. Paracancerous tissue of 15 cases was selected as controls.Materials: the polyclonal antibodies against COX - 2, VEGF - C and VEG-FR - 3 and SABC immunohistochemical kits and DAB substrate solution were purchased from Wuhan Boster Biotechnology, Inc.Methods: immunohistochemical staining SABC method was performed, all slides were treated with 0.01 mol/L citric acid buffer (PH =6. 0) to recover the antigen activity in autoclave, antibodies against VEGFR - 3 as a marker of lymphatic endothelial cells.Assessment: outcome definition of COX - 2 and VEGF - C were stained palm yellow particle in cytosol, positive cells > 10% as positive, ≤10% as negative. Single lymphatic endothelial cell or cluster and structure like tube being stained yellow with VEGFR - 3 were defined as a lymphatic vessel. To definite' the LVD, we identified the area containing the most EGFR - 3 ( + ) vessels (hot spot) at low magnification(40 ) , and counted the mean lymphatic vessel number of three hot spots at high magnification (200 ).Statistical analysis: statistical methods t test , x~2 test, Spearman rank correlation test and Kaplan - Meier survival analysis were performed by SPSS software version 10.0.ResultsExpression of COX - 2 and VEGF - C in patients with gastric cancer;the positive expression of COX -2 and VEGF - C in 51 cases was 62. 8% and 60. 7% respectively, however, was negative in 15 cases paracancerous tissue.The relationship between expression of COX — 2 and VEGF - C and clinico-pathologic parameters in patients with gastric cancer: expression of COX -2 was positive correlated with VEGF - C (r = 0. 74, P < 0. 01) , clinical stage( r = 0. 34, P < 0.05 ) and lymph node metastasis(r = 0. 57, p < 0. 01) , but was negative correlated with pathologic differentiation ( r = -0.58, p < 0. 01) . Expression of VEGF - C was positive correlated with lymph node metastasis(r =0.45 , p <0.01) , but no correlation with clinical stage and differentiation (both p >0. 05).The relationship between lymphatic vessel density ( LVD) and expression of COX - 2 and VEGF - C and clinicopathologic parameters in gastric cancer: thelymphatic vessels located in tumor tissue. LVD was positive correlated with lymph node metastasis( r = 0. 70, p < 0. 01) , clinical phage( r = 0. 40, p < 0. 01) , COX-2(r=0.69, p<0.01) and VEGF -C(r =0.45, p<0.01) , negative correlated with pathologic differentiation(r = -0.42, p<0.01).The relationship between expression of COX — 2 and VEGF - C and survival in patients with gastric cancer;COX - 2 expression was negative correlated with 5 — year survival by Kaplan — Meier survival analysis. The 5 — year survival of patients with negative COX - 2 expression (36. 8% ) was significantly higher than those with positive COX -2 expression (15. 6% , P <0. 05). No relationship was founded between the expression of VEGF - C and 5 - year survival (P >0.05).ConclusionThe expression rate of COX — 2 and VEGF - C was high in human gastric cancer, and the relationship between of them was positive. The expression of COX - 2 and VEGF - C was positive correlated with lymph node metastasis and lymphangiogenesis, which indicated that COX - 2 could promote lymphangiogen-esis and lymphatic metastasis by up - regulating expression of VEGF - C in human gastric cancer.The patients with COX - 2 negative expression had better survival than COX - 2 positive expression, and the detection of COX - 2 in gastric cancer tissues might be significant in prognosis prediction. However, the expression of VEGF - C in gastric cancer tissues had no correlation with survival of patients.