| Gastric carcinoma is the commonest malignant tumor of digestive tract and the average 5 y survival rate is about 15-20%. Chemotherapy is one of the chief therapeutic methods to the patients with gastric carcinoma of intermediate and advanced stage. However, the therapeutic effect is not very well for the occurrence of MDR. The mortality rate due to cancer in our country is above 90% for MDR. Overcoming MDR may lead to success of chemotherapy. MDR describes the phenomenon that tumor cells exposed to one antitumor agent become resistant to other chemically and structurally diverse chemotherapeutic agents. The MDR mechanism of malignant tumor is complex and it's still unknown. It may relate with the follows, (1)the overexpression of mdr-1 gene leads to the drug efflux increasing and uptake decreasing. (2)the overexpression of MRP(multidrug resistance-associated protein) leads to the distribution alteration of drug in cytoplasma and then leads to the drug far from its target. (3) the exocytosis of LRP (4)the changes of cell detoxicity mechanism and DNA repair, eg. MDR related with GST-Ï€.(5)the change of drug target in quanlity and quantity weakens the drug toxicity. (6)the increase of PK.C activity leads to the phosphorylation of P-gp and TopoII. (8)the change of extracellular environment (pH, temperature, saturation of O2). However, the MDR mechanism of gastric carcinoma can't be fully understood for the above and it needs further investigation.Ever since the appearance of proteomics and the application of proteomic project, the proteomics have provided a new idea for the life science study as well as MDR. The MDR mechanism could be studied from the whole protein level of tissue and cell. Although some success have been achieved for the MDR mechanism studying on the gene level. It will be more valuable to compare and select the protein related with MDR directly from the protein level, it shows an important significance for studing and...
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