| BackgroundChemotherapy is one of comprehensive modalities for malignant tumors. Resistance to drugs is not only its main failure reason but also one big obstacle in the treatments of cancer. Therefore, it is of paramount importance to develop drugs that are less resistant and better efficacious. Leading one of them is Chinese medicine synergist. However, the mechanism remains unclear.Garlicin is active substance in garlic. It can be divided into five ingredients , one of which is called diallyl trisulfide, has a strong anti - mold and anti -bacteria ability and is characteristically stable. Its constitutional and molecular formula is CH2 = CH - CH2 - S - S - S - CH2 - CH = CH2 and C6H10S3, respectively. It is widely used to preclude aging and blood coagulation, decrease blood — fat and hypertension, and treat virus and so on, in addition to prevent and cure infectious diseases. Moreover, the recent investigations have demonstrated that it can block the formation and inhibit activation of carcinogens, and preclude mutation and aberration;that it can directly kill cancer cell;that it can regulate cell cycle, inhibit the growth and promote the apoptosis of cancer cell;that it also can interfere with the growth of tumor by regulating the body immuno-logic function. Now many researchers are involved in investigations that Garlicin can decrease the resistance to and increase the activity of chemotherapy. However, the mechanism remains elucidated.The researches in the;recent years have indicated that P - gp and GST - π , whose levels of expression are directly proportional to resistance, are the substance bases of MDR of malignant tumors. In this study, we used immunofluo-rescence and confocal laser microscope technique to measure GST — π and P —gp expression in SGC -7901 ,a human gastric cancer cell, treated with Garlicin, so that further understand the mechanism that Garlicin exhibits synergistic interaction with chemotherapeutic drugs.Purposewe used immunofluorescence and confocal laser microscope technique to measure GST - tt and P - gp expression in SGC -7901 ,a human gastric cancer cell, treated with Garlicin, so that further understand the mechanism that Garlicin exhibits synergistic interaction with chemotherapeutic drugs.MethodsWe used the immunofluorescence staining method. Briefly, exponentially growing cells were plated into 6 — well microplates and were treated with graded concentrations of garlicin for 24h. After being stained by FITC and Cy3, the cells were observed and photographed under the confocal laser scanning microscope. PBS was negative control. Leica confocal software was used to analyze fluorescence intensity of the slides, in which the sectors including dense cells were examined and twenty tumor cells in a highpower field were chosen and investigated randomly. The data include results from three separate experiments. The average fluorescence intensity was considered relative level of expression of the proteins.Results1. The double mark fluorescence showed that P - gp and GST - it overlapped reciprocally and formed into yellow granules, which either pervasively distributed in cytoplasm or in nucleus like dots. Their fluorescence distributions were almost equivocal.2. The level of expression of P - gp and GST - it in SGC - 7901 cells: SGC -7901 cells coexpress both P - gp and GST - it protein. The fluorescent inten-sity of P - gp in the cells treated with no drug and in the cells exposed to 5 jxg/ ml, 10|xg/ml, 15|xg/ml, 20|xg/ml of garlicin was 132. 28 ± 17. 25, 113. 85 ± 18.70 ,85.40 ± 17.60 , 70.09 ± 17.81, 53.91 ± 14. 30 ,respectively. That of GST-it was 130.07 ±17.33, 111.21 ±16.18 ,93.17 ±16.08 ,69.01 ±15. 10 , 50.15 ± 15.02, respectively. This study has demonstrated that the expression of P - gp and GST - tt decreased as the concentrations of garlicin increased.ConclusionThe mechanism that garlicin decreased resistance to chemotherapy and increased the activity has association with decreasing the expression of P - gp and GST - tt , substance bases for MDR of cancer, exhibiting theoretical evidences for using garlicin in a clinical setting, conquering resistance, and increasing action. This investigation demonstrated that SGC - 7901 cells, a human gastric cancer cell line, coexpress both P - gp and GST - tt , the marker of resistance, indicating that P — gp and GST — tt play a very important role in the resistance of gastric cancer and that these two markers has intimate association in their expression. |
