Objective To detect the characteristic of multidrug resistance gene products expressions in gastric cancer tissues, including glutathione-s-transferase π (GST-π), P-glycoprotein (P-gp), topoisomerase Ⅱ (Topo-Ⅱ), thymidylate synthase (TS), and multidrug resistance related protein (MRP), and analyze their clinical significance for the therapy of gastric cancer. Methods SP immunohistochemical stain was used to detect GST-π, P-gp, Topo-Ⅱ, TS and MRP expressions in sample of 48 gastric cancer tissues and 10 normal gastric mucosa. And their corresponding clinical data were comprehensive analyzed. Results The expressions of GST-π, P-gp, Topo-Ⅱ, TS and MRP had notable differences between the gastric cancer tissues and normal gastric mucosa (GST-π： P＜0.01； P-gp： P＜0.01； Topo-Ⅱ： P＜0.01； TS： P＜0.05； MRP： P＜0.05). Positive expression rates of GST-π, P-gp, Topo-Ⅱ, TS and MRP in gastric cancer tissues were 72.9% (35/48), 56.3% (27/48), 83.3% (40/48), 41.7% (20/48) and 39.6% (19/48), and positive expression rates of them in normal gastric mucosa were 10.0% (1/10), 0 (0/10), 0 (0/10), 0 (0/10) and 0 (0/10) corresponding. Their positive expression rates were closely relevant to the degree of differentiation (P＜0.01), but not to the patients’ sex, age, tumour site, size of tumour, invasive depth and lymph node metastasis (Pgt;0.05). Conclusions The expressions of GST-π, P-gp, Topo-Ⅱ, TS and MRP in gastric cancer tissues exist obvious heterogeneity. Their overexpression underlie the multidrug resistance of gastric cancer. The joint detection of GST-π, P-gp, Topo-Ⅱ, TS and MRP can be looked as an important symbol for guiding its chemotherapy.
Objective To review the application advancements of ATP-binding cassette (ABC) transporter in medical research.Methods Relevant literatures about the applications of ABC families in medical research were reviewed. Results ABC families mainly took roles in transporting substances across cell membrane. Some of them were useful for the prediction of drug resistance and the prognosis of malignant tumors. Others were target s for molecular researches. Their expressions or mutations might be related with the occurrence of diseases. Conclusion ABC families are very important in the diagnosis and therapy for diseases. Thus they are very promising tools for future medical research.
Objective To study the effects of survivin antisense RNA on SGC7901 cell’s apoptosis and chemosensitivity to taxotere, and to investigate its effect on the expression of multi-drug resistance gene-1 (MDR-1). Methods Survivin antisense eukaryotic vector anti-pcDNA3-svv was transfected into SGC7901 cell lines by lipofectamine and positive clones were screened out then. Survivin protein and MDR-1 mRNA were measured by western blot and RT-PCR, respectively. Apoptosis that was induced by anti-pcDNA3-svv was observed by electronic microscope, and the sensitivity of SGC7901 cell to taxotere was examined by MTT. Results The expressions of survivin protein and MDR-1 mRNA in transfected SGC7901 cells both decreased more significantly than that of non-transfected cells (P＜0.05， P＜0.01), and the indices of MDR of transfection group and non-transfection group were 0.196±0.013 and 3.126±0.019, respectively, at the late phase of apoptosis, which had a significant difference between each other (P＜0.01), IC50 of the transfected cells to taxotere was （16.7±1.98） ng/ml and that of the non-transfected cells was (55.7±1.89) ng/ml, which also had a significant difference (P＜0.01). Conclusion Surivivin antisense RNA could induce the apoptosis of SGC7901 cancer cell line and could increase the cells’ sensitivity to taxotere, which may help to reverse drug resistance.
Objective To investigate the reversal of the multidrug resistant gene mdr1 in vivo by antisense oligodeoxynucleotide （ASODN） on the basis of study in vitro. Methods The cultured drug-resistant human hepatocellular carcinoma cells were injected under the skin of axilla to establish the tumor model of nude mice. mdr1 ASODN accompanied by Lipofectamine were injected locally and ADM was injected intraperitoneally. Control 1 and control 2 were locally injected by Lipofectamine and normal saline separately, and ADM was also injected intraperitoneally. Results As time went on the tumor size increased and from the 5th day on alterations were marked, tumor size in different time phase showed marked difference to the prior time phase with significant difference (P＜0.05）. Tumor size in group ASODN was marked smaller than that of other 3 groups after the 5th day (P＜0.05)，while tumor size of group control 1,2 and group SODN in different phase showed no significant difference (Pgt;0.05). The results suggested that SODN and Lipofectamine showed no marked effect on tumor growth of nude mice and ASODN had marked inhibition effect on tumor growth. Conclusion mdr1 ASODN can also reverse multidrug resistance of drug-resistant human hepatocellular carcinoma cells in vivo. After the treatment the tumor’s growth in nude mice will slow down in a range of time.
ObjectiveTo establish multidrugresistance cell substrain of human hepatocellular carcinoma and to investigate its characteristics.MethodsSMMC7721 cell strain was cultured in Adriamycin(ADM). The multidrugresistance cell substrain SMMC7721/ADM was harvested after a long period of culture by gradually increasing the concentration of ADM and its characteristics were investigated. Results①The drug resistance of SMMC7721/ADM to ADM increased by 33.3 times, to Vincristine 16.8 times, to Diamminedichloroplatinum 2.8 times. ②The drug resistance cell substrain had almost the same growth velocity as its parental generation. The doubling time was 32.0 hours and 30.5 hours respectively. They had the analogous growth curves. ③The obvious difference between the drug resistance cell substrain and its parental generation was that the former’s microvilli became thick, short and scattered by scanning and transmitting electron microscopy. ④The multidrug resistance cell substrain kept the characteristics of hepatocellular carcinoma, it could be transplanted into the subcutaneous tissue of nude mice. ⑤The drug resistance of the cell substrain reduced to 28.0% and 9.2%after removal of the drug for 1 month and 2 months respectively, its drug resistance could remain stable (35.4 times) after 2 months of culture in ADM (0.04 μg/ml).ConclusionThe SMMC7721/ADM cell substrain has the stable fundamental characteristics of a drug resistance cell strain.
Objective To review the recent studies on the multidrug resistance of breast cancer. Methods The literatures of recent years on the studies of multidrug resistance, multidrug resistance protein and breast cancer resistance protein were reviewed. Results Multidrug resistance resulted from multiple factors. How to identify the sensibility of chemotherapy drugs and select individual therapeutic regime early were important to improve the survival rate and life quality of breast cancer patients. Conclusion These studies on multidrug resistance of breast cancer are helpful to predicting the effect and outcome of chemotherapy and overcoming the barrier of drug resistance.
【Abstract】Objective To review the advances in overcoming multidrug resistance of tumors caused by mdr1 gene.Methods Different ways of overcoming multidrug resistance of tumors caused by mdr1 gene in the literatures were reviewed. Results One of the important reasons causing multidrug resistance was due to the overexpression of mdr1 gene and its product Pglycoprotein. There were two ways to overcome multidrug resistance of tumors through mdr1 genes mRNA and its product Pglycoprotein effectively.Conclusion The clinical test of the unitary way to overcome multidrug resistance of tumors is unsatisfactory, combining different ways to overcome multidrug resistance of tumors will be the hot spot of tumors research in the future.
ObjectiveTo construct the recombinant adenovirus vector carrying antisense multidrug resistanceassociated protein (MRP) and transfect the human drugresistant hepatocellular carcinoma cell line(SMMC7721/ADM). MethodsThe fragment of MRP gene encoding 5′region was cloned reversely into the shuttle plasmid pAdTrackCMV, with the resultant plasmid and the backbone plasmid pAdEasy1,the homologous recombination took place in the bacteria and the recombinant adenoviral plasmid was generated. The adenoviruses were packaged and amplified in 293 cells. Then the cell line of SMMC7721/ADM was transfected with the resultant adenoviruses.ResultsThe recombinant adenovirus vector carrying antisense MRP was constructed successfully. The viral titer was 2.5×109 efu/ml, and more than 90% SMMC7721/ADM cells could be transfected when the multiplicity of infection（MOI） was 100. ConclusionThe recombinant adenovirus vector constructed by us could introduce the antisense MRP into the human drugresistant hepatocellular cell line effectively, which would provide experimental basis for the mechanisms and reversal methods of the multidrug resistance in human hepatocellular carcinoma.
ObjectiveTo evaluate the effect of neoadjuvant chemotherapy and find the mechanism of multidrug resistance. MethodsTwenty patients with gastric cancer and 31 patients with colorectal cancer underwent neoadjuvant chemotherapy and then operations. The preoperative specimens were stained by immunohistochemical techniques for testing p53,multidrug resistanceassociated protein (MRP), glutathione S transferase（GST）, telomerase. Resection specimens were evaluated for chemotherapy effect by routine histology; at the same time, the postoperative morbidity and mortality were observed. ResultsIn 51 patients, the response rate of neoadjuvant chemotherapy was 27.45%(14/51),so multidrug resistance was a kind of common phenomena in gastrointestinal carcinomas. The postoperative morbidity was 15.69%(8/15), the main operation complication was infection,the mortality was 1.96%(1/51),only one person died from severe infection.The expression rate of p53, MRP, GST, telomerase was 58.0%,51.0%,66.7%,74.0%respectively, the location of p53 was at cell nucleus,location of MRP,GST was at cell memberane and cytoplasm,location of telomerase was at cytoplasm.The response rate had nothing to do with age, sex and metastasis. But it was related with p53 and telomerase expression. ConclusionNeoadjuvant chemotherapy is an effective, safe therapy. But the rate of drug resistance is high in gastrointestinal carcinomas, and the response rate is related to p53, telomerase expression.
Objective To study the expression and significance of multidrug resistance-associated protein (MRP) gene in hepatocellular carcinoma (HCC). Methods Reverse transcription polymerase chain reaction (RT-PCR) assay was used to detect the expression of MRP mRNA in 25 fresh specimens of the primary HCC and its surrounding liver tissues. Immunohistochemistry LSAB technique was adopted to test MRP in 60 HCC specimens. The drug sensitivity was also tested by flow cytometry.Results The positive expression rates of MRP mRNA and MRP protein in primary HCC were 44.00%(11/25) and 45.00%(27/60) respectively. All the intensity of expression was low, but significant higer than its surrouding liver tissues (P＜0.05). The intensity and expression rate of MRP protein in 5 recurrent HCC had a tendency to increase. There was a correlation between the expression of MRP mRNA and MRP protein in 25 patients using RT-PCR and immunohistochemistry assay (Plt;0.05). Detected by flow cytometry, the average sensitivity of drugs in vitro of 60 HCC sp-cimens were 5-FU （15.80±7.63）%，DDP（18.45±9.59）%，ADM（17.95±7.99）%，MMC（16.60±8.69）% and CTX（17.40±10.14）%. Only 5FU and ADM were significantly affected by the expression of MRP protein (Plt;0.05).Conclusion The expression of MRP in primary HCC may be one of the important mechanisms of the intrinsic and acquired drug resistance in HCC. To study the expression of MRP could give a predictive value in HCC chemotherapy.