The Expression Of M2-PK And VEGF And Its Effects On Multidrug Resistance In Gastric Cancer

Background:There are approximately934,000new cases which were diagnosed as gastric cancer annually in the world. Nearly two-thirds of all gastric cancer cases are found in developing countries, with42%in China alone. Gastric cancer remains an aggressive disease with a high mortality, this malignancy remains the second leading cause of cancer-related death worldwide and its recurrence is often the ultimate cause of death. Tumor angiogenesis plays a critical role in tumor growth and metastasis. The glycolytic pyruvate kinase isoenzyme type M2(M2-PK) plays a key role by channeling glucose carbons either into synthetic processes or towards glycolytic energy production. In tumor cells, M2-PK is predominantly present as a dimeric form known as tumor M2-PK, which is thought to allows tumor cells survive in environments with varying oxygen and nutrient supplies. P-gp protein is a production encoed by multi-drug resistance gene (multidrug resistance gene, MDR). It lasts a long time for the study of relationship between P-gp protein and gastric cancer. There still is a big controversy to define P-gp protein expression as an indicator of gastric cancer,Objective:In this study, we aimed to examine the expression of M2-PK and VEGF, and to determine whether these biological parameters could be used to predict the outcome of patients with advanced gastric cancer.Methods:We test the M2-PK and VEGF expression in surgical pathology specimes of142patients with advanced gastric cancer by immunohistochemical staining. We also analyzed the correlation between the expressions of M2-PK and VEGF, and the relationship with clinicopathological parameters in patients with advanced gastric cancer. Depending on differences of the characters of gastric cancer cells and the sensitivity to cisplatin, we choose two gastric cancer cell line SGC-7901, BGC-823and the resistant durg gastric cancer cell line MGC-803as the research material, and we studied the nucleic acid level and the protein level of M2-PK, P-gp, and the protein level of VEGF using quantitative ELISA and quantitative PCR respectively. We also studied the influence to different proteins of gastric cancer cell lines after cisplatin being administered.Results:1. The histopathology immunohistochemical staining of M2-PK and VEGF staining rates in142pathology specimes with advanced gastric were61.26%and65.49%, and there were the remarkable relationships between the tumor size and their expressions (p=0.0001; p=0.0017), the violated extent of tumor and their expressions (p=0.0024; p=0.0261) and the lymph node metastasis of tumor and their expressions (p=0.036; p=there is a significant correlation between0.028). Low expression of VEGF and M2-PK in tumor tissue has a better prognosis in patients with gastric cancer as the independent factor. The five-year survival rate of low expression of VEGF and M2-PK was significantly better than the high expression of VEGF and M2-PK in patients with advanced gastric cancer. The expression of VEGF and M2-PK in patients with advanced gastric cancer has a significant correlation (r=0.718, p<0.01).2. The ELISA results showed that the fluctuation of M2-PK protein in three gastric cancer cell lines was not remarkable, especially in the cisplatin-resistant cell line of MGC-803which did not show obvious difference to other two kinds ordinary gastric cancer cell lines. The M2-PK protein in three gastric cancer cell lines is very low when cisplatin were intervented and the difference among them is very small. We had not detected P-gp protein in the three gastric cancer cell lines by ELISA. VEGF protein levels in three gastric cancer cell lines were higher, after adding cisplatin, we found that VEGF levels has a negative correlation with the concentrations of cisplatin in the BGC-823cell lines which indicated that cisplatin inhibited gastric cancer cells produce VEGF;3. The PCR results showed that when cisplatin dose increased for SGC-7901, BGC-823gastric cancer cell lines, the levels of M2-PK gene and VEGF gene expression gradually declined, but the expression of P-gp gene relatively constant, when cisplatin dosing increased for MGC-803cell line, the expression of M2-PK gene and P-gp gene gradually increased, but the expression of VEGF gene has no significant change.Conclusions:1. The expression of M2-PK and VEGF, tumor size, depth of invasion, lymph node metastasis and TNM staging were the effective predictor for evaluating the malignant behavior, the degree of invasion and metastasis of advanced gastric cancer.2. The experiments confirmed that P-gp is a multiple drug resistance gene in gastric cancer cells. The expression of M2-PK gene and VEGF gene in the drug resistant cell lines increased with cisplatin dosage, suggesting that these two genes can reflects the drug resistance of gastric cancer cells to some extent.3. In this study, the data and research methods perhaps is helpful to the diagnosis, treatment, multidrug resistance and prognostic evaluation of gastric cancer in the future.