Significance of vascular endothelial growth factor expression and its correlation with inducible nitric oxide synthase in gastric cancer

AIM: To investigate the clinical significance of the expression of VEGF165mRNA and the correlation with vascular endothelial growth factor (VEGF) protein and inducible nitric oxide synthase (iNO) in human gastric cancer.METHODS: We tested VEGF165mRNA expression in 31 cases of resected gastric cancer specimens and normal paired gastric mucosae by RT-PCR. Total RNA was extracted with TRIzol reagents, transcribed into cDNA with oligo (dT15)priming, inner controlled with β-actin expression and agarose gel isolated after PCR. VEGF expression was quantitated with IS1000 imaging system. Meanwhile we also examined expression levels of VEGF protein and iNOS in 85 cases of gastric cancer. All paraffin-embedded samples were immunohistochemically stained by streptavidin -peroxidase method (SP).RESULTS: The mean expression of VEGF165mRNA in gastric cancer was 1.125±0.356, significantly higher than that of normal paired mucosae, which was 0.760±0.278.The data indicated that the expression level of VEGF165mRNA was well related to lymph node metastasis and TNM stages of UICC. The expression levels in patients with lymph node metastasis and without lymph node metastasis were 1.219±0.377 and 0.927±0.205 respectively (P＜0.05). The expression in stages Ⅰ, Ⅱ, Ⅲ, Ⅳ was 0.934±0.194, 1.262±0.386 respectively (P＜0.01). Further analysis showed the lymph node metastasis rate in the group with over-expression of VEGF was higher than that in the group with low expression of VEGF (83.3% vs46.2%),and the ratio of stage Ⅲ+Ⅳ in the group with overexpression of VEGF was also higher than that in the group with low expression with VEGF (77.8% vs 33.8%) (P＜0.05).The positive rates of expression of VEGF protein and iNOS in 85 cases of gastric cancer were 75.4% and 58.8%respectively, and 50.1% of the patients showed positive staining both for iNOS and VEGF, the correlation with the two factors was significant (P=0.018). But more intensive analysis showed the immunoreactive grades of VEGF were not associated with that of iNOS.CONCLUSIONS: The expression of VEGF165mRNA is well related with lymph node metastasis and TNM stages of UICC in gastric cancer, and is concerned with the invasiveness and metastasis of gastric cancer. The relationship can be observed between the expression of VEGF and iNOS in gastric cancer.