The Study On The Relationship Between DCR3 Expression And Lymph Node Metastasis, VEGF-C, VEGF-D Expression In Gastric Cancer

BACKGROUND AND OBJECTIVESGastric cancer is one of the most malignant tumors worldwide. It is the second largest cause of cancer related death. Surgery is the main method to treat gastric cancer. It is debated about the extent of lymphadenectomy. Someone emphasized the value of extensive lymphadenectomy (D2 and more), which could avoid missing the metastatic lymph nodes. In others' opinion, however, Extended lymph node dissection couldn't improve the survival time, but increasing the operative complication and mortality. Evaluating the extent of lymph node metastasis preoperatively can help surgeons to choose optimal extent of lymphadenectomy, which may avoid unnecessary extended lymph node dissection in condition that all the positive lymph nodes are dissected. However current methods do not offer an accurate preoperative estimation of lymph node involvement. Recently, the molecular makers are used to evaluate preoperatively the lymph node metastasis, and the idea of "molecular staging" of gastric cancer is introduced. Decoy receptor 3(DcR3) is a member of the TNF receptor family discovered in 1998. Study had shown that DcR3 expression was associated with the metastasis of gastric cancer. But, There are no reports about the relationship between the DcR3 expression and the extent of metastatic lymph nodes in gastric cancer. It is controversial about whether DcR3 mRNA expression is accompanied DcR3 gene amplification or not in malignant tumor. The mechanism of DcR3 promoting the lymphtic metastasis is not clear. In our study, the relationship between expression of DcR3 mRNA and extent of the metastatic lymph nodes in gastric cancer was evaluated, and the correlation between DcR3 genomic amplification and DcR3 mRNA expression was determined. The association between the expression of DcR3 mRNA and the expression of vascular endothelial growth factor-C(VEGF-C), vascular endothelial growth factor-D (VEGF-D), the lymphangiogenesis factors, was studied, to evaluate the reason why the gastric cancer with DcR3 expression has more tendency for lymphtic metastasis. The value of VEGF-C, VEGF-D predicting theextent of the metastatic lymph nodes in gastric cancer was evaluated simultaneously.METHODSPART ONE: Sixty-two patients with primary gastric carcinomas diagnosed and operated at Department of Surgery, Second Affiliated Hospital, Medical School of Zhejiang University, between February 2003 and January 2004 were included in the study. The expression of DcR3 mRNA in cancerous tissues was investigated by reverse transcription-polymerase chain reaction (RT-PCR) analysis and compared with the values derived from the respective normal mucosa. Amplification products were separated by electrophoresis on agarose gels, photographed, and analyzed using the densitometric software. The DcR3 mRNA expression ratios in difference groups of patients were calculated. The index of DcR3 mRNA expression was determined by semi-quantity method, which evaluating the expressing intensity of DcR3 mRNA. The index was the ratio of densities multiplying area of DcR3 band and β -actin band. Data were analyzed with SAS 8.1. The chi square test or Fisher exact probability test was used to assess the difference of expression ratio of DcR3 mRNA between cancerous tissues and normal gastric mucosa, and in cancerous tissues with difference pN classification. The Wilcoxon test determined the differences of index of DcR3 mRNA expression between cancerous tissues and normal gastric mucosa, and in cancerous tissues with difference pN classifications.PART TWO: Genomic DNA was isolated from cancerous tissues of gastric cancer and respective normal gastric mucosa. The relative amplification fold of DcR3 gene of cancerous tissues and respective normal gastric mucosa were determined with fluorogenic quantitative PCR (FQ-PCR). DcR3 gene relative amplification fold = Ct (Threshold Cycle) of DcR3 gene/ Ct of β -globin gene. The relative amplification fold of DcR3 gene of cancerous tissues and respective normal gastric mucosa was compared using paired t test. The difference be...