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Objectives: Nephrotic syndrome is a common disease of the urinary system. The aim of this study is to explore the effect of astragalus polysaccharides (APS) on multidrug resistance gene 1 (MDR1) and P-glycoprotein 170 (P-gp170) in adriamycin nephropathy rats and the underlying mechanisms., Methods: A total of 72 male Wistar rats were divided into a control group, a model group, an APS low-dose group, an APS high-dose group, an APS+micro RNA (miR)-16 antagomir group and an APS+miR-16 antagomir control group, with 12 rats in each group. Urine protein (UP) was detected by urine analyzer, and serum cholesterol (CHOL), albumin (ALB), blood urea nitrogen (BUN), and creatinine (SCr) were detected by automatic biochemical analyzer; serum interleukin-6 (IL-6), IL-1β, tumor necrosis factor α (TNF-α) levels were detected by ELISA kit; the morphological changes of kidney tissues were observed by HE staining; the levels of miR-16 and MDR1 mRNA in kidney tissues were detected by real-time RT-PCR; the expression levels of NF-κB p65, p-NF-κB p65, and P-gp170 protein in kidney tissues were detected by Western blotting; and dual luciferase was used to verify the relationship between miR-16 and NF-κB., Results: The renal tissue structure of rats in the control group was normal without inflammatory cell infiltration. The renal glomeruli of rats in the model group were mildly congested, capillary stenosis or occlusion, and inflammatory cell infiltration was obvious. The rats in the low-dose and high-dose APS groups had no obvious glomerular congestion, the proliferation of mesangial cells was significantly reduced, and the inflammatory cells were reduced. Compared with the high-dose APS group and the APS+miR-16 antagomir control group, there were more severe renal tissue structure damages in the APS + miR-16 antagomir group. Compared with the control group, the levels of UP, CHOL, BUN, SCr, IL-6, IL-1β, TNF-α, and MDR1 mRNA, and the protein levels of p-NF-κB p65 and P-gp170 in the model group were significantly increased (all P <0.05); the levels of ALB and miR-16 were significantly decreased (both P <0.05). Compared with the model group, the levels of UP, CHOL, BUN, SCr, IL-6, IL-1β, TNF-α, and MDR1 mRNA, and the protein levels of pNF-κB p65 and P-gp170 in the low-dose and high-dose APS groups were significant decreased (all P <0.05); and the levels of ALB and miR-16 were significantly increased (both P <0.05). Compared with APS+miR-16 antagomir control group, the UP, CHOL, BUN, SCr, IL-6, IL-1β, and TNF-α levels, MDR1 mRNA, and the protein levels of p-NF-κB p65 and P-gp170 were significantly increased (all P <0.05). The levels of ALB and miR-16 were significantly decreased in the APS+miR-16 antagomir group compared with the APS+miR-16 antagomir control group (both P <0.05)., Conclusions: APS can regulate the miR-16/NF-κB signaling pathway, thereby affecting the levels of MDR1 and P-gp170, and reducing the inflammation in the kidney tissues in the adriamycin nephropathy rats.

Objective: To investigate the role of ubiquitin-specific peptidase 22 (USP22) in colorectal cancer multidrug resistance and its correlation with multidrug resistance genes P-gp and MRP1, and to preliminarily explore the mechanism of USP22 affecting colorectal cancer resistance. Methods: USP22 over-expression plasmid was transfected into colorectal cancer cells (RKO, SW480)with low expression of USP22. Cell counting kit (CCK-8) assay was used to detect the effect of USP22 on oxaliplatin resistance in colorectal cancer cells. The cells were treated with oxaliplatin of the same concentration. Western blot method was used to detect the expression of apoptosis-related proteins cleaved-caspase3, Bcl-2, and drug resistance proteins MRP1, P-gp in the cells. The cell efflux test was used to detect the effect of up-regulated USP22 on Calcein-AM and rhodamine123. Immunohistochemical methods were used to detect the expressions of USP22 and P-gp in the oxaliplatin chemotherapy-sensitive group and the drug-resistant group and to analyze the correlation between USP22 and MRP1, P-gp. Results: CCK-8 assay showed that the IC 50 values of SW480-USP22 (SW480 cells overexpressing USP22) treated with oxaliplatin for 24 h and 48 h was (4.62±0.05)μmol/L and (2.32±0.04)μmol/L respectively; which was 2.7 times and 3.0 times higher than that in control cells, respectively. After treating with 1.25 μmol/L oxaliplatin for 48 h, USP22 overexpression can inhibit SW480 cells apoptosis. The fluorescence intensity of calcein-AM and rhodamine123 in the SW480-USP22 group were significantly increased when compared with that in the control cells (both P <0.01). The protein expression levels of MRP1 and P-gp in SW480-USP22 cells were significantly increased when compared with that in the control cells(both P <0.01). Immunohistochemistry showed that the positive expression rates of USP22, MRP1, and P-gp in the oxaliplatin chemotherapy-sensitive group were significantly lower than those in the chemotherapy-resistant group, the difference was statistically significant (all P <0.05), and USP22 was positively correlated with the expressions of MRP1 and P-gp in colorectal cancer tissues ( r 1 =0.377, r 2 =0.423, both P <0.05). Conclusions: The up-regulation of USP22 is related to the acquired resistance of colorectal cancer cells to oxaliplatin. USP22 may be involved in the process of platinum-based chemotherapy resistance of colorectal cancer by regulating the expressions of P-gp and MRP1.

Objective: To investigate the effect of compound matrine injection on morphine tolerance in mice with lung cancer in situ and the expressions of multidrug resistance gene 1 (MDR1) and P-glycoprotein (P-gp). Methods: A mouse model of lung cancer in situ and morphine tolerance mode was established. The mice were injected with gradient concentration of compound matrine. The pain thresholds under different conditions were measured by thermal radiation tail-flick method. The mRNA level of MDR1 was tested by reverse transcription polymerase chain reaction (RT-PCR) and the protein level of P-gp was detected by western blot. The DNA binding activity of cyclophosphoadenosine response element binding protein (CREB) to the promoter of MDR1 gene was detected by electrophoretic mobility shift assay (EMSA). Results: The maximum analgesic percentage (MPE) of the mice in the morphine group was (85.21±6.53)% on the 8th day, and decreased to (38.45±5.52)% and (28.14±4.52)% on the 10th and 12th day, respectively, which indicated the morphine tolerance of mice with lung cancer in situ.The MPE of the mice in the group treated with morphine and compound matrine injection (300 mg/kg) was (79.34±6.50)% on the 8th day, and decreased to (62.16±5.53)% and (40.20±4.50)% on the 10th and 12th day, respectively.The results of RT-PCR assay showed that the relative expression levels of MDR1 mRNA in the brain tissues of mice in the morphine group, saline group, morphine combined with compound matrine injection (300 mg/kg) group and compound matrine injection (200 mg/kg) group were 2.33±0.79, 1.04±0.38, 1.37±0.38, and 1.43±0.53, respectively. There were statistically significant differences between the morphine group and the normal saline group, the morphine group and the morphine combined with compound matrine injection (300 mg/kg) group ( P <0.05). There was no significant difference between the normal saline group and the compound matrine injection (200 mg/kg) group ( P =0.05). The results of western blot showed that the relative expression levels of P-gp protein in the brain tissue of mice in the morphine group, saline group, and morphine combined with compound matrine injection (300 mg/kg) group were 1.86±0.40, 1.00±0.23, and 1.27±0.27, respectively. The expression of P-gp protein in the morphine group was significantly higher than those of the normal saline group and the morphine combined with compound matrine injection (300 mg/kg) group ( P <0.05). The DNA-binding activity of CREB in the saline group was (0.23±0.07) Pu, significantly lower than (0.89±0.23) Pu of morphine combined with naloxone group and (0.80±0.23) Pu of morphine group ( P <0.05). While the CREB DNA binding activity of morphine combined with compound matrine injection (300 mg/kg) group was (0.79±0.21) Pu, implicated that compound matrine had marginal effect on the DNA-binding activity of CREB ( P >0.05). Conclusion: Compound matrine injection can significantly improve morphine tolerance and drug resistance of lung cancer through inhibiting the upregulations of MDR1 and P-gp induced by morphine.

Objective: To investigate the effects of simvastatin(SIM) and serum free medium(SFM) on the expression of multidrug resistance gene(MDR1) and protein of SHI-1 cells., Methods: Trypan blue exclusion assay was used to detect the proliferation level and viability of SHI-1 cells after treatment with SIM and culture in SFM; The multi-drug resistant protein p-gp was measured by flow cytometry after culture in SFM for 1 to 3 days and treatment with various concentration of simvastatin. The effect of SFM culture and SIM treatment on the expression of MDR1 trascript was detected by qPCR; ELISA was used to measure the change of cellular cholesterol after culture in SIM and SFM. Chemosensitivity assay was performed after treatment with SIM for SHI-1 cells., Results: Compared with control group, the growth of SHI-1 cells cultured in SFM decreased in a time-dependent manner. The growth-inhibitory effect was markedly increased when SHI-1 cells were treated with SIM and SFM. The mRNA level of MDR1 gene decreased after SIM treatment or/and culture in SFM. P-gp protein was downregulated in SHI-1 cells cultured in SFM or/and treated with SIM. The cellular cholesterol level increased when the cells were cultured in SFM. Total cellular cholesterol level decreased in SHI-1 cells treated with SIM and cultured in SFM. Chemosensitivity assays found that pre-treatment with SIM could increase the cytotoxicity of DNR to SHI-1 cells., Conclusion: Culture with SIM and SFM can downregulate the expression of MDR1 gene and p-gp protein in SHI-1 cells. SIM also can enhance the chemotherapeutic sensitivity of SHI-1 cells.

This paper was aimed to investigate the microRNA associated with multidrug resistance gene MDR1 of salvianolic acid A reversal in lung cance. Human lung cancer A549 cells were divided into normal control group and drug group, and the MDR1 expression levels were determined by real-time quantitative PCR. MicroRNA expression profiling of normal control group and drug group were detected by using the latest microRNA microarray. Quantitative RT-PCR was used to validate the differentially expressed miRNA. Forecast of miRNA associated with MDR1 multi-resistant genes of up-regulated miRNA. Experimental results showed that the dosage of MDR1 expression level significantly lowered compared with control group. The miRNA expression spectrum analyses of human lung cancer A549 cells to drug group and the control group were detected by microRNA microarray, 426 differentially expressed miRNA were screened out. Then target prediction were performed for difference up-expression of miRNA and found that there were four obvious increase of miRNA associated with MDR1 multi-resistant genes. Real-time quantitative PCR for 4 microRNA verification, the results were consistent with the chip. So the author considered that salvianolic acid A down lung cancer multidrug resistance gene MDR1 is likely to be affected by the miRNA expression and regulation of target genes, to further clarify the traditional Chinese medicine to reverse multi-drug resistant mechanism provides the experimental basis., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Chinese Pharmaceutical Association.)

Multidrug resistance-related proteins (MRP) are identified as ATP-dependent efflux pumps, the expression abnormality of which has close relationship with multidrug resistance (MDR) in a variety kinds of malignancies, leading to the failure of chemotherapy. The relationship between the expression of MRP and acute leukemia remains to be proved, since experiments and clinical researches are still insufficient. In this article, the structure, distribution, function, and relation of MRP to MDR and prognosis of acute leukemia are reviewed.

Objective: To explore the feasibility and safety of mdr1 gene transferred into placenta derived mesenchymal stem cells (P-MSCs) by reconstructed retroviral vector., Methods: Human P-MSCs were isolated and expanded by Percoll density gradient and then transduced repeatedly by reconstructed retroviral vector containing mdr1 gene. The transfection and expression of mdr1 gene was detected by reverse transcription-polymerase chain reaction (RT-PCR) and fluorescence-activated cell sorting (FACS). Meanwhile, the biological features of mdr1-MSCs were identified and analyzed., Results: The expression of mdr1mRNA was found in transfected cells. The expression of P-glycoprotein (P-gp) encoded by mdr1 gene was (27.6 ± 5.1)% in the transfected P-MSCs cells versus (0.4 ± 0.1)% in the non-transfected P-MSCs cells (t = 14.291, P < 0.01). The percent of P-MSCs at quiescent phase (G0/G1 phase) was around 95.40% and it was in accord with the characterization of stem cells. The mdr1-MSCs exhibited typical ultrastructures of low-differentiated stem cells. Moreover, they still retained the potency of adipogenic and osteogenic differentiation in the presence of appropriate conditioned media., Conclusion: A stable expression of P-gp may be obtained by reconstructed retroviral-mediated transfection in vitro. And transfected MSCs retain the characteristics of stem cells.

Objective: To investigate whether there is intercellular transfer of functional P-glycoprotein(P-gp) from P-gp-positive cells to P-gp-negative cells in vitro., Methods: HepG2/GFP cells, a HepG2 cell line stably expressing GFP, were co-cultured with HepG2/ADM cells, an adriamycin-resistant cell line derived from HepG2 cells. The distribution of P-gp in hepatocellular carcinoma cell was observed under laser scanning confocal microscope (LSCM). Immunomagnetic beads were used to separate HepG2/GFP cells from the mixed culture. The abundance of P-gp was analyzed by western blot, and the expression of mdr1 mRNA was detected by qRT-PCR., Results: Yellow fluorescence was detected in HepG2/aqMDR cells, green fluorescence was detected in HepG2/GFP cells, red fluorescence was detected in HepG2/ADM cells by LSCM. The level of P-gp protein in HepG2/aqMDR cells was lower than that in HepG2/ADM cells, but higher than that in HepG2/GFP cells (q = 35.07, P < 0.05) and HepG2 cells (q = 36.87, P < 0.05). The expression of mdr1 mRNA in HepG2/ADM cells was higher than that in HepG2/aqMDR, HepG2 and HepG2/GFP cells, but there was no significant difference in mdr1 mRNA among HepG2/aqMDR, HepG2 and HepG2/GFP cells (F = 2.30, P > 0.05)., Conclusions: P-gp can transfer from drug resistant hepatocellular cells to sensitive hepatocellular carcinoma cells. This study suggests a novel mechanism of multidrug resistance in hepatocellular carcinoma.

Background and Objective: The therapeutic effects of chemotherapy for malignant neoplasms are still unsatisfactory. This study was to evaluate the chemosensitivity of colorectal cancer tissues to therapeutic agents using histoculture drug response assay (HDRA), and explore the correlation of chemosensitivity to the expression levels of multidrug resistance (MDR) genes and proteins., Methods: Twenty-two specimens of colorectal cancer were collected. The inhibition rates of single agents, including epirubicin, cisplatin (DDP), oxaliplatin, 5-FU, taxetere, irinotecan, and combinations of these agents, including 5-FU+epirubicin+DDP, 5-FU+irinotecan, 5-FU+oxaliplatin, 5-FU+taxetere+ DDP on colorectal cancer tissues were evaluated by HDRA. The agent whose inhibition rate was greater than 30% was considered sensitive, and the sensitivity was calculated. mRNA and protein levels of MDR genes and proteins in colorectal cancer tissues were measured by RT-PCR and immunohistochemistry., Results: Among the single agents, the inhibition rate of oxaliplatin (17.5%) and sensitivity of cancer tissues to 5-FU (36.4%) were the highest. In the combination groups of agents, the inhibition rate of 5-FU+ oxaliplatin (54.1%), and sensitivity of cancer tissues to 5-FU+epirubicin+DDP (71.4%) and to 5-FU+taxetere+DDP (71.4%) were the highest. The inhibition rates of and sensitivity of cancer tissues to combined agents were higher than those of single agents (P<0.05). Expressions of MDR1, multidrug resistance protein-1 (MRP1), ABC-binding cassette transporter superfamily-G-2 (ABCG2) mRNA were detected in 88.9%, 55.6% and 55.6% of specimens respectively; while those of MDR1, MRP1 and ABCG2 proteins were detected in 55.6%, 33.3%, and 50.0% of specimens respectively. Expressions of mRNA and proteins had no correlation in MDR1, MRP1 and ABCG2 (P>0.05). High expression of ABCG2 protein was correlated to the resistance of colorectal cancer cells to epirubicin (P<0.05)., Conclusions: Expressions of MDR proteins are correlated to chemosensitivity of colorectal cancer to some extents. By combining HDRA with measurement of MDR genes and proteins, chemosensitivity of individual tumors may be predicted to guide selection of effective chemotherapeutic agents.

This study was aimed to design and screen short hairpin RNA (shRNA) molecules targeting multidrug resistance gene (mdr1), as well as to investigate the effects of shRNA expression vector on K562/A02 cells. Mdr1-shRNA expression vector was transfected into K562/A02 cells by lipofectamine 2000, and G418 was added to screen and establish the stable expression cell strain. The expressions of mdr1 mRNA and protein were detected by real-time RT-PCR and Western blot respectively. The sensitivity of cells to chemodrugs after interference were tested by CCK8 assay. The function of p-glycoprotein was determined by Rhodamine 123 efflux experiment. The results showed that all of 4 mdr1-shRNA expression vectors could significantly knockdown the expression of p-glycoprotein as compared with control vector, moreover, the vector targeting 508 - 526 sites of mdr1 gene was the best one. It is concluded that the mdr1-shRNA expression vector gained by screening can significantly knockdown the expression of mdr1 gene and reverse leukemia drug resistance, paving the way for the application of RNAi in the following animal experiments.

Background and Objective: The therapeutic effects of chemotherapy on gastric cancer are still unsatisfactory. Predicting chemosensitivity of tumors as therapeutic guidance could help to improve the efficacy of chemotherapy. This study was to evaluate the chemosensitivity of gastric cancer to single or combined therapeutic agents by histoculture drug response assay, to evaluate the expression levels of multidrug resistance (MDR) genes and proteins and analyze their correlations to the chemosensitivity of gastric cancer., Methods: The inhibitory effects of single agents, including epirubicin, cisplatin (DDP), oxaliplatin, 5-fluorouracil (5-FU), taxetere, irinotecan, and combined regimens, including 5-FU, epirubicin plus DDP, 5-FU plus irinotecan, 5-FU plus oxaliplatin, and 5-FU, taxetere plus DDP, on 22 specimens of gastric cancer were evaluated by histoculture drug response assay. The mRNA and protein expression of MDR1, MRP1 and ABCG2 in gastric cancer were detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry., Results: The inhibition rate of gastric cancer by 5-FU (29.8%) and sensitivity of gastric cancer to 5-FU (50.0%) were the highest among single agents; the inhibition rate of gastric cancer by 5-FU, taxetere plus DDP (59.8%) and sensitivity to 5-FU, epirubicin plus DDP (77.3%) were the highest among combined regimens; combined regimens achieved higher inhibition rate and sensitivity as compared with single agents (P<0.05). The positive rates of MDR1, MRP1, and ABCG2 mRNA were 90.9%, 54.5%, and 77.3%; the positive rates of MDR1, MRP1, and ABCG2 proteins were 36.4%, 54.5%, and 36.4%. High expression of MDR proteins in gastric cancer was related with the resistance to epirubicin (P<0.05)., Conclusion: High expression of MDR1, MRP1, ABCG2 proteins in gastric cancer is related with the resistance to epirubicin, which indicates that these MDR genes may play a role in conferring the drug resistance to epirubicin.

This article introduces the characteristics and establishment of MDCK-MDR1 cell line, and its applications as an in vitro model for the assessment of the membrane permeability properties of drugs. MDCK-MDR1 cell model is widely used in drug screenings, and the study of mechanisms of drug interaction and absorption or transport. The review summarizes the progress and applications of MDCK-MDR1 cell model. Because there is high polarized P-glycoprotein (P-gp) expression in MDCK-MDR1 cells, it could be used as a drug transport model to screen P-gp substrates or inhibitors, as well as models of intestinal mucosa, blood brain barrier and kidney. Although there are some disadvantages in MDCK-MDR1 cell model, it is an effective tool for implementing permeability of drug in an optimal fashion.

Resistance to the cytotoxic actions of antineoplastic drugs remains a barrier to the establishment of curative chemotherapy regimens for cancer. Over-expression of P-glycoprotein (P-gp), encoded by the MDR1 gene is the major molecular mechanism enhancing efflux pump for various anticancer agents, hence caused MDR. Transcription factor, DNA methylation, histone acetylation/deacetylation, phosphorylation and glycosylation and MDR1 gene polymorphisms play pivotal role in regulation of P-glycoprotein, and may become new therapeutic targets. This paper summarized the advances of studies on expression and regulation of P-glycoprotein.

Objective: To examine the differential gene expression among adenoid cystic carcinoma ACC-M, low metastasis ACC-2 and low differentiated mucoepidermoid carcinoma MEC-1 with gene array, and detect three important genes with real-time quantitative PCR., Methods: Gene array was used to screen the differential genes, then three important genes were selected and detected by real-time quantitative PCR., Results: The gene contents of MDR-1, MRP-1 and CCD1 were MEC-1 > ACC-M > ACC-2, MEC-1 > ACC-M > ACC-2 and MEC-1 > ACC-M > ACC-2 respectively., Conclusions: Drug resistance of MEC-1 is related with high content of MDR-1. High metastasis of ACC-M is concerned with high content of MRP-1 and low content of CCD-1. Low metastasis of ACC-2 has a relationship with low content of MRP1.

Aim: To investigate the chemosensitivity to lidamycin (C-1027) in mdr1 gene overexpressing cancer cell lines established by drug induction and by gene-transfection., Methods: DNA was cloned by RT-PCR and then eukaryotic expressing recombinant plasmid pcDNA3. 1/mdrl was constructed. Using Lipofectamine 2000, a strain of stably transfected human hepatoma cancer cells, HepG2/mdrl, was obtained. The mdr1 mRNA level, P-glycoprotein (P-gp) level and the activity of P-gp to extrude drugs in cancer cells were determined by RT-PCR, immunofluorescence analysis and rhodamine 123 efflux assay. The chemosensitivity of cancer cells with low or high mdr1 expression to lidamycin and other antitumor drugs was tested by MTT assay., Results: The mdr1 mRNA and P-gp levels in KBv200, MCF-7/ADR, and stably transfected HepG2/mdr1 cells were much higher than that in respective parent KB, MCF-7 and HepG2 cells. The IC50 values of lidamycin for KBv200, MCF-7/ADR and HepG2/mdrl cells were (0.24 +/- 0.20) nmol x L(-1), (0.028 +/- 0.011) nmol x L(-1), and (0.020 +/- 0.011) nmol x L(-1), respectively. Compared with parental cells, the values of resistant fold for KBv200, MCF-7/ADR and HepG2/mdr1 cells to lidamycin were 6.8, 1.6 and 1.3 fold; to adriamycin were 37.2, 181.3 and 8.8 fold; to taxol were 336.8, 49.2 and 40.3 fold, respectively., Conclusion: Lidamycin is highly active to multidrug resistant cancer cells. The chemosensitivity of those resistant cancer cells to lidamycin is approximately at the similar level as that of parent cancer cells.

Objective: To screen effective sequences of small interfering RNA targeting MDR1 gene in human gastric cancer SGC7901/VCR cells., Methods: Four siRNAs (MDR1si326, MDR1si1513, MDR1si2631 and MDR1si3071) targeting MDR1 gene were designed and synthesized by in vitro transcription. The siRNA duplexes were used to transfect into the human gastric cancer SGC7901/VCR cells. The expression level of MDR1 mRNA and P-gp were detected by RT-PCR and Western blotting, respectively. The accumulation of intracellular adriamycin (ADR) was examined by flow cytometry and the cell sensitivity to ADR was demonstrated by MTT., Results: The SGC7901/VCR cells treated with 4 siRNAs led to reversal effect on multidrug resistance to different extents. Among the SGC7901/VCR cells treated by siRNAs for 48 h, the expression level of MDR1 mRNA in cells of MDR1si326 or MDR1si2631 group (0.42 +/- 0.07 or 0.49 +/- 0.02) was more decreased than that in cells of MDR1si1513 or MDR1si3071 group (P < 0.05). The accumulation of ADR in cells of MDR1si326 group was the most; in cells of MDR1si2631 group, more; in cells of MDR1si3071 group, lower and in cells of MDR1si1513 group, the lowest (P < 0.05). The relative reversal efficiency of cells of MDR1si2631 group to ADR was the highest and in cells of MDR1si326 group, higher (P < 0.05). There was no significant difference in the relative reversal efficiency between the cells of MDR1si1513 and MDR1si3071 groups (P > 0.05). The expression level of P-gp in cells of MDR1si326 group was the lowest among the SGC7901/VCR cells treated by siRNAs for 72 h., Conclusion: The MDR1si326 with most, MDR1si2631 with more, MDR1si3071 with less and MDR1si1513 with least reversal effects on MDR1 gene mediated multidrug resistance were found in the human gastric cancer SGC7901/VCR cells.

Researches on MDR (multidrug resistance) of tumor presently focus on seeking chemosensitizers with more targets, high efficiency and low toxicity from traditional Chinese medicine. This paper reviews the research progress in the reversion of MDR of leukemia, hepatocarcinoma, breast carcinoma and oral epithelioid neoplasia by TDM compound, its extracts, its groups of active ingredients or its active ingredients.

Objective: To observe the effect of tetrandrine on the P170 production expressed by multi-drug resistance gene, lung resistant protein (LRP), and topoisomeras II and elucidate the underlying molecular mechanism., Method: Cellular model of multi-drug resistance was established in S180 tumor cell by means of the scheme of PFC chemotherapy at the dosage lower than that with curative effect. P170, LRP and TOPO II were measured by flow cytometry after the mouse model was treated with tetrandrine for 4 weeks., Result: tetrandrine obviously reduced the enhancement of express of P170, LRP and the activity of TOPO II in the tumor cells with multi-drug resistance induced by chemotherapy., Conclusion: Tetrandrine significantly inhibits the multi-drug resistance of tumor cells induced by chemotherapy via diminishing both the expression of multi-drug resistance gene and the activity of topoisomeras II.

Background & Objective: The latest researches showed that myc protein could up-regulate the expression of human telomerase reverse transcriptase (hTERT), multidrug resistance gene 1(MDR1), multidrug resistance-related protein (MRP) in some kinds of tumors, and hTERT is correlated with efficiency of anti-tumor chemotherapy. This study was to investigate relations among expressions of hTERT, MDR1, MRP mRNA, and C-myc protein in non-small cell lung cancer (NSCLC)., Methods: Expressions of hTERT, MDR1, MRP mRNA in 113 cases of NSCLC tissues were detected by in situ hybridization, expression of C-myc protein was detected by SP immunohistochemistry, their correlations with clinicopathologic features of NSCLC were statistically analyzed., Results: Positive rates of hTERT, MDR1, MRP mRNA, and C-myc protein in NSCLC tissues were 80.5%, 51.3%, 80.5% and 68.1%, respectively. Expressions of MDR1, MRP mRNA, and C-myc protein were significantly related to that of hTERT mRNA (P<0.05). Expression of C-myc protein did not correlate with expression of MDR1 or MRP mRNA. All 4 factors have no correlation with clinicopathologic features of NSCLC (P>0.05)., Conclusion: Expression of hTERT mRNA may be related to those of MDR1, MRP mRNA, and C-myc in NSCLC. Overexpression of C-myc protein may be one of the molecular regulatory mechanisms of hTERT mRNA.

Background & Objective: Multidrug resistance of tumor cells often leads to failure of chemotherapy. The over-expression of P-glycoprotein (P-gp), encoded by multidrug resistance 1 (mdr1) gene, plays an important role in multidrug resistance of breast cancer. This study was to explore the feasibility of silencing mdr1 gene by small interfering RNA (siRNA) in drug resistant breast cancer cell line MCF-7/ADR., Methods: The siRNA oligonucleotides strand designed previously was inserted into pSilencer3.1-H1 Hygro vector, the plasmid was transformed into E.coli. After amplification, the plasmid was purified, and sequenced to determine whether the ligation between siRNA insert and the vector was correct, then transfected into MCF-7/ADR cells, and relevant sensitive MCF-7 cells. MCF-7/ADR cells were screened by hygromycin, surviving cells were cultured. The positive rate of P-gp was detected by flow cytometry, and positive rate of mdr1 gene was detected by real-time relatively quantitative polymerase chain reaction (PCR). Adriamycin (ADM) resistant experiment was performed on MCF-7/ADR cells with siRNA., Results: Positive rate of P-gp in MCF-7/ADR cells was decreased from 99.8% (before siRNA transfection) to 12.3% (after siRNA transfection). Real- time PCR revealed that the threshold cycle value of MCF-7/ADR cells increased from 25.22 to 30.64 after transfected with siRNA. The IC(50) of ADM for MCF-7/ADR cells transfected with siRNA was 0.51 micromol/L, while that for MCF-7/ADR cells without transfection was 17.88 micromol/L., Conclusion: siRNA can silence mdr1 gene in MCF-7/ADR cells, may become a new, effective medical technique.

To produce leukemic STI571-resistant cell lines and to explore the molecular mechanism of STI571-resistance, cell lines K562-n and K562-n/VCR were induced by exposing cells to gradually increasing STI571 concentration of culture medium to have STI571-resistance and major biological characteristics between these subclones and the parent cells were compared. The results showed that a STI571-resistant cell line based on multidrug-resistance was established, which exhibited 23.41-fold resistance to STI571, 662.26-fold resistance to VCR and cross-resistance to HHT. K562-n/STI was generated from K562-n and had some characteristics of MDR. The intracellular accumulation of DNR in K562-n/STI and K562-n/VCR/STI were 33.24 and 18.76 respectively. Transcription of mdr-1 gene in both K562-n/STI and K562-n/VCR/STI was positive. Cell doubling time of K562-n/STI and K562-n/VCR/STI was significantly longer than that in their parent cells (P <0.05). And proliferation index was also higher than that in parent cells (P <0.05). It is conclusion that the tolerance of K562-n cells to STI571 can be augmented by adding low-dose of STI571 into the culture medium repeatedly. K562-n/STIs expressed MDR at some extent, and transcription of mdr-1 gene in K562-n/STIs was positive. As K562-n is a cell line used to develop human leukemia in nude mice, K562-n/STI and K562-n/VCR/STI 571 will contribute to the study of mechanism of STI571-resistance as in vitro and in vivo experimental models.

Objective: To study the reverse effect of ligustrazine (TMP) on HepG2/ADM, a herd of hepatocellular carcinoma cell, multidrug resistance (MDR) and the influence of P-gp170 expression., Method: The reverse effect of ligustrazine on HepG2/ADM cell was observed, with the methods of cell culture, MTT's analyze, RT-PCR and Flow cytometric, etc., Result: Ligustrazine could make MDR of cell line of HepG2/ADM reduce the expression of P-gp170, enhance the density of adriamycin in cell and increase the adriamycin's cytotoxicity. With the Flow cytometric, the results of RT-PCR showed the transcriptional activity of the MDR1 decreased., Conclusion: Ligustrazine can reverse MDR of HCC cell line of HepG2/ADM and has prospect in clinical use.

Objective: To study the synergistic effect of STI571, an inhibitor of tyrosine kinase in combination with arsenic trioxide (As(2)O(3)) on a multidrug-resistant leukemia cell line expressing bcr-abl., Methods: The cytotoxic effect of STI571 alone or in combination with different concentrations of As(2)O(3) on both bcr-abl and mdr1 positive leukemia cell line K562-n/VCR was detected by MTT method., Results: The cytotoxic effect of STI571 (1 micromol/L) combined with As(2)O(3) at concentrations 10(-5), 10(-6), 10(-7), 10(-8) mol/L (IC(50) 0.155 micromol/L) on K562-n/VCR cells was significantly higher than that of As(2)O(3) alone (IC(50) 1.879 micromol/L). The synergistic interaction on K562-n/VCR cells increased the cytotoxic effect by 12.1-fold., Conclusion: Combination of STI571 with As(2)O(3) has a synergistic inhibiting effect on leukemia cells expressing bcr-abl and mdr1.

To explore the Fas and mdr-1 expression and their correlation in multidrug resistance (MDR), Fas and mdr-1 expressions of bone marrow from 59 patients with newly diagnosed AL before therapy and after complete remission were detected by direct immunofluorescence with flow cytometry and semi-quantitative RT-PCR, respectively. The results showed that in newly diagnosed AL patients, Fas expression in AML was higher than in ALL (P < 0.05), mdr-1 expression in AML and ALL had no difference (P > 0.05), the expressions of Fas and mdr-1 had correlation (r = -0.282, P < 0.05) in AL; the results of simple-variable and multivariable COX survival factor model analysis suggested that Fas and mdr-1 expressions were prognostic factors for the effect of therapy and survival. Log rank test, comparing the groups of Fas(+) with Fas(-), mdr-1(+) with mdr-1(-), demonstrated that the CR rates and median remission time of every two groups had significant difference. It is concluded that in AL, Fas and mdr-1 expressions have high correlation with the effect of treatment, Fas expression probably is one of the favorable prognostic factors, mdr-1 is an unfavorable prognostic and less effective factor.

Objective: To investigate the relationship between the expression of glucosylceramide synthase (GCS) mRNA in vincristine-resistant KBV(200) human cancer cell line and multidrug resistance (MDR) of the cancer cells., Methods: Reverse transcriptional polymerase chain reaction (RT-PCR) was employed to analyze the differential expression of GCS mRNA between KBV(200) and KB cell lines and the changes in the mRNA expressions of GCS and mdr1 gene in KBV(200) cells after reversion of MDR. The effects of de-phenyl-z-palmaitoylamino-3-morpholine-1-propanol (DL-PPMP) and verapamil in reversing MDR of the cells were evaluated by MTT assay., Results: KBV(200) cells exhibited significantly increased expressions of GCS and mdr1 gene, whereas mdr1 gene failed to be detected in the parental KB cells. DL-PPMP within the concentrations ranging from 5 to 25 micromol/L could inhibit the expression of GCS gene, with the maximum inhibition achieved at 25 micromol/L. Verapamil at the concentration of 10 micromol/L was already sufficient to induce inhibition of GCS expression in KVB(200) cells, which was more manifest with the concentration of 15 micromol/L. DL-PPMP and verapamil were found to inhibit mdr1 gene expression in KBV(200) cells at the mRNA level, and complete inhibition occurred after a 48-hour DL-PPMP treatment at 25 micromol/L., Conclusion: The inhibition of GCS and mdr1 gene expressions is positively correlated with the concentrations of DL-PPMP and verapamil, which can reverse MDR by inhibiting synthesis of GCS and mdr1 gene, indicating the positive correlation between the expression of GCS gene and MDR in KBV(200) cells. GCS gene might play an important role in MDR during tumor progression.

Objective: To examine the changes in the function and expression of multidrug resistance gene (mdr1) and P-gly-coprotein (P-gp) in nasopharyngeal carcinoma (NPC) CNE1 cell following irradiation for determining the sequential order of radiotherapy and chemotherapy in the treatment of NPC., Methods: The expressions of mdr1 gene and its protein P-gp as well as the function of P-gp efflux were examined in CNE1 cells before and after irradiation exposure by reverse transcriptional polymerase chain reaction (RT-PCR), Western blotting and flow cytometry, respectively., Results: Irradiation of CNE1 cells induced a long-term overexpression of mdr1 gene and P-gp and reduction in intracellular daunorubicin accumulation., Conclusion: Irradiation decreases the chemotherapy sensitivity of CNE1 cell, and induction chemotherapy should be therefore performed before radiotherapy in the treatment of advanced NPC.

Objective: To study the molecular mechanism underlying multidrug resistance (MDR) and identify unknown genes that might be involved in drug resistance development in K562/A02 cells., Methods: K562/A02 was induced by gradually increasing the ADM concentration in culture medium of K562 cells, the differential expression of associated genes between K562 and K562/A02 was determined with cDNA microarray. Overexpression of neurofilament protein NF-H gene in K562/A02 cells was confirmed with RT-PCR and immunocytochemistry. Anti-sense oligodeoxynucleotides were transfected into K562/A02 cells by lipofectamine in order to further analyze the role of NF-H in drug resistance., Results: Comparing with the expression profiles, we found upregulation of 5 transcripts and downregulation of 7 transcripts in response to MDR of K562/A02 cells. The overexpression of NF-H, one of the 5 upregulated genes, was confirmed. After being treated with antisense oligodeoxynucleotides of NF-H and mdr1, the cellular adriamycin concentration increased significantly, but antisense NF-H alone did not have significant effect on drug resistance phenotype., Conclusion: The development of MDR in K562/A02 cells is multifactorial. NF-H may be involved in the drug resistance of K562/A02, which may provide a new marker of diagnosis and a new target of therapy.

Objective: The aim of this study was to investigate the mechanism(MDR) of multidrug resistance(MDR) of mucoepidermoid carcinoma in salivary gland., Methods: 40 cases of mucoepidermoid carcinoma in salivary gland were examined the MDR gene product P-glycoprotein using a monoclonal antibody JSB-1. And 10 of them were also investigated by detecting the expression of GST-pi. All the cases had not been accepted any therapy before the samples were collected., Results: 1. Positive expression of JSB-1 was observed in 27 of the 40 specimens. The positive expression was related not only with clinical stage, but also with differentiation degree. 2. The GST-pi positive expression was found in 9 of 10 cases. There was no significant different between the positive expression of JSB-1 and GST-pi., Conclusion: JSB-1 and GST-pi play an important role in MDR of mucoepidermoid carcinoma.

Objective: To investigate the role of nuclear factor kappa B (NF-kappaB) decoy oligodeoxynucleotides (ODNs) in the process of differential regulation of the lung cancer cells A549 by ciglitazone., Methods: NF-kappaB decoy ODNs were transfected into A549 cells with Lipofect AMINE 2000, and electrophoretic mobility shift assay (EMSA) was performed to investigate the activation of NF-kappaB, while the level of mdr1 was observed by Western blot. When ciglitazone was added, the proliferation was observed by growth curve and the differentiation of cells was observed by flow cytometry, and the expression of cyclinD1 was observed by Western blot., Results: EMSA showed that the decoy ONDS-decreased the activation of NF-kappaB in A549, and Western blot showed that the decoy ONDS decreased the level of mdr1. Ciglitazone significantly inhibited the growth and induced the differentiation of A549 cells that were transfected with NF-kappaB decoy ODNs. There were more cells arrested in G(1)/G(0) phase and the expression of cyclinD1 was markedly down-regulated as compared to the control cells., Conclusion: NF-kappaB decoy ODNs could enhance the effects of ciglitazone on proliferative suppression and differential induction of A549 cells.

To investigate the correlation between methylation and expression of multidrug resistance (mdr1) gene, restriction endonuclease HpaII combined with competitive PCR technique was used to quantitatively detect the methylation status of two CCGG sites located at -110 and -50 bp (region I and II) up to the transcription start site in mdr1 promoter in 54 AL and 9 MM patients. Semi-quantitative RT-PCR was used to detect the expression level of mdr1 gene. The results showed that inverse correlation between methylation rate of either region or total methylation rate and expression of mdr1 gene was observed. The correlation in the region I (r = -0.64) was closer than that in the region II (r = -0.4). High expression rate of mdr1 ascended significantly in low methylation group (n = 36) (P < 0.001). In comparison with chemotherapy sensitive group (n = 8), the methylation rate in refractory AL patients (n = 16) was lower (P = 0.05) in the region I, P < 0.05 in the region II and total regions. Comparing with the untreated patients (n = 36), the methylation rate in the region I and total methylation rate were lower in the patients with chemotherapy (n = 14) (P < 0.05). The methylation rate in the region II was also decreased after chemotherapy, however, no statistical significance was shown (P > 0.05). Increased mdr1 expression level accompanying with decreased methylation rate after chemotherapy was found, although no significant difference was shown (P = 0.06). It is concluded that the expression level of mdr1 gene was associated with the methylation status of CCGG in -110 and -50 bp upstream to the transcription start site, especially the -110 site. In both the patients treated with chemotherapy and the refractory patients, the methylation level of mdr1 gene decreased relatively. The rising expression of mdr1 gene after chemotherapy was associated with the decrease of methylation level.

Objectives: To investigate the reversal effect of gene MDR1 and MRP with combinational antisense phosphorothioate oligonucleotide on Drug-resistant human hepatocellular carcinoma cells SMMC-7721/ADM., Methods: SMMC-7721/ADM was transfected with synthetic antisense phosphorothioate oligonucleotides complementary to gene MDR1 and MRP mediated by Lipofectamine. Drug sensitivity was measured by MTT assay, Fluorescence intensity of cells was determined by flow cytometric analysis, RH123 and DNR retention was assayed by confocal scanning laser microscopy., Results: ASODN of MDR1+MRP increased the sensitivity of SMMC-7721/ADM to chemotherapeutic drug more significantly than that any of MDR1 and MRP did separately. But they did not enhance the inhibition expression of protein of p190 or p170., Conclusion: Drug-resistance could be reversed significantly when antisense phosphorothioate oligonucleotide of MDR1+MRP were transfected into drug-resistant human hepatocellular carcinoma cells SMMC-7721/ADM together.

Objective: To establish a CDDP-resistant cell line from human tongue squamous cell carcinoma cell line Tca8113 and to compare the drug-resistance gene expression between them., Methods: The concentration of CDDP added to Tca8113 cells was increased stepwise to induce the CDDP-resistance. The index of drug-resistance was estimated by MTT assay. The expression of MDR-1, MRP, GST-pi and Bcl-2 was measured by RT-PCR optical density OD., Results: The CDDP-resistant cell line, Tca8113/CDDP was established, whose drug-resistance index was 9.2. The expression of MDR-1, MRP, cyclin D1 and Bcl-2 increased respectively., Conclusion: The expression of drug-resistance gene in Tca8113/CDDP was significantly higher than that in Tca8113.

To explore the possibility of leukemia cell line of both bcr-abl and mdr-1 positive were cross-resistant to tyrosine kinase inhibitor STI571 and its reversal way, the inhibitory effect of STI571 on K562-n/VCR cells was detected with MTT method and reverse effects of CsA, TAM, IFN-alpha and CsA cominated with IFN-alpha were observed. The results showed that K562-n/VCR cell line expressing bcr-abl and mdr1 positive was resistant to STI571, and could be reversed by 5.18, 1.82 and 1.67-fold respectively, when treated with CsA, TAM, and IFN-alpha. It could be reversed by 34.87-fold with combination of half-dose CsA and IFN-alpha. In conclusion, amplification of mdr1 gene may contribute to drug-resistance of bcr-abl positive leukemic cells against STI571. The reversal agents, CsA, TAM and IFN-alpha show obviously reverse effects on drug-resistance. The combination of half-dose of both CsA and IFN-alpha display stronger effect than the full dose of either.

This preject is to explore the reversal efficacy of calmodulin antagonist berbamine (BBM) on multidrug resistance (MDR) and its mechanism. Human erythroleukemic cell line K562 and its adriamycin-resistant counterpart K562/A02 were used in the study. The cells were co-cultured with ADR and BBM in different concentrations. MTT assay was used to analyze the effect of BBM on cell growth inhibition. According to the MTT assay, the 50% inhibitory concentration (IC(50)), the multiples of drug resistance and increased sensitivity of ADR were calculated. The concentration of intracellular ADR and expression level of P-gp were detected by flow cytometry (FCM). The expression level of mdr1 mRNA and survivin mRNA was detected by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) with beta-actin as internal reference. The results showed that IC(50) of ADR in K562 and K562/A02 cells was 1.16 +/- 0.09 micro mol/L and 37.47 +/- 1.76 micro mol/L, respectively. The resistant multiple of K562/A02 cells to ADR was 32.30 higher than that of K562 cells. BBM increased the chemo-sensitivity of ADR in K562/A02 cells with dose-dependent relationship, i.e. when 5, 10 and 20 micro mol/L BBM was added in the culture the chemo-sensitivity of ADR was increased to 2.01-, 9.68-, and 41.18-fold (P < 0.01), respectively. After treating K562/A02 cells by 5 or 10 micro mol/L BBM for 2 hours the accumulation of intracellular ADR was increased to 1.41- and 1.52-fold (P < 0.01), respectively. Treating by BBM for 72 hours decreased 4.12% (P < 0.05) and 27.09% (P < 0.01) of P-gp expression, respectively, meanwhile down-regulated expression of mdr1 mRNA and survivin mRNA was found. In conclusion, BBM could increase intracellular concentration of ADR in K562/A02 that down-regulated expression level of mdr1 mRNA and P-gp and survivin so that the sensitivity of K562/A02 to ADR was increased significantly.

Objective: To set up a mdr1 multidrug resistant model of orthotopic transplantation of liver carcinoma in nude mice by intermittent abdominal chemotherapy., Methods: The hepatocellular carcinoma cell line HepG2 was first cultured, then subcutaneous carcinoma was produced to form the tumor donor mice. An orthotopic mdr1 hepatoma was produced by implanting the tumor fragment subserosally to the mice liver, and intermittent chemotherapy with Pharmorubicin given to induce drug resistance. Physical examination, ultrasonography, spiral CT and laparotomy were used to examine the growth of the tumor. RT-PCR and SP method by the monoclonal antibody JSB-1 were adoped to detect the expression of mdr1-mRNA and p-gp protein., Results: There was no mortality. The successful rate of tumor implantation is 88% (22/25), the successful rate of supplementary implantation was 100% (3/3), and the successful rate of induction of drug resistance was 80% (16/20). The expressions of mdr1-mRNA and p-gp in the Pharmorubicin group were 23 folds and 13 folds of the control group, respectively., Conclusions: The nude mice mdr1 multidrug resistant model of orthotopic liver carcinoma were set up successfully, with its features similar to clinical cases. It would be helpful for the further study of the diagnosis and reversal strategy of the MDR phenomenon.

Objective: To investigate the impact of non-target gene mutations and reduced permeability of the outer membrane on quinolone resistance and multiple antibiotic resistance (mar) in Escherichia coli., Methods: Several high-level quinolone resistant isolates whose strains were accompanied by concurrent resistant to several antibiotics were selected. The PCR products of marOR region were sequenced to detect the possible gene changes and then the strains' outer membrane proteins (Omps) were extracted to analyze on the constitutive profiles., Results: We found two site mutations in R410 isolate: 1,870(T-->C, Val-->Ala) and 1,879(A-->C, terminator-->Ser). The OmpF deficiency was found in all 3 resistant strains., Conclusion: The increased expression of MarA induced by gene mutations in marOR and the constitutive profile changes of the Omps (OmpF deficient strains) may play some role in the quinolone resistance and multiple antibiotic resistance of Escherichia coli.

To elucidate the effect of established primary bone marrow stromal layers on the gene transduction of human hematopoietic stem/progenitor cells (HSC/HPC), mononuclear cells (MNC) from adult bone marrow were isolated by centrifugation on Ficoll-Hypaque gradients and plated in stromal culture medium. The cells were incubated until passage 4 to establish primary stromal layers. The HSC/HPC prestimulated by cytokines were transduced by retroviral supernatant containing mdr1 gene in presence of irradiated stroma-contact support. Transduced cells were plated in a colony-forming unit assay with and without vincristine (VCR) to assess the efficiency of transduction. Individual colonies were also analyzed by polymerase chain reaction (PCR) for the presence of provirus. The results showed that the mixed adherent cell layers were formed when adult bone marrow stromal cells were incubated for four to six weeks, mainly being composed of fibroblasts. In the presence of stroma-contact support, the average of gene transduction efficiency in marrow-derived progenitors increased 2.1 to 3.3 folds measured by colony-forming assay and/or PCR, significantly higher than those without support of stroma. It is concluded that the presence of bone marrow stroma support in combination with cytokine facilitates augmenting the extent of retroviral-mediated gene transduction.

Background & Objective: This study was designed to seek an efficient and safe method for transfer of genes of large size., Methods: The retroviral vector containing different kinds drug resistance genes-class 1 aldehyde dehydrogenase (ALDH1) and multidrug resistance gene (MDR1) was linearized by the restriction enzyme NdeI digestion, and introduced into the packaging PA317 cells by electroporation. Selection was performed by vincristine (VCR) and 4-hydroperoxycyclophosphamide(4-HC) to obtain ALDH1 and MDR1 stably expressing cells. The integration of provirus, transcription and translation of foreign genes were confirmed by Southern blot, reverse transcription(RT)-PCR and flow cytometry, respectively. The safety of this delivery system was verified by testing helper virus(envelop gene) using nested PCR., Results: Both ALDH1 and MDR1 were successfully transduced into PA317 cells by electroporation. Stable integration of foreign genes in host cells genome was determined by Southern hybridization blot. The transcription of ALDH1 and MDR1 was demonstrated by RT-PCR. The overexpression of P-glycoprotein encoded by the downstream gene MDR1 with approximately a 4-fold increase in 98% cells was analyzed by flow cytometry. No helper virus can be detected by nested PCR assay., Conclusion: These results implicate that the introduction and overexpression of both ALDH1 and MDR1 genes in vitro is attainable by a simple and convenient electroporation method, with the character of safety and high efficiency.

To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human O6-methylguanine-DNA-methyltransferase (MGMT) and multidrug resistance gene (MDR1) increase resistance to 1,3-Bis(2-Chloroethy1)-1-Nitrosourea (BCNU) and P-glycoprotein effluxed drugs, the present authors obtained a full length cDNA fragment encoding MGMT from liver tissue of a patient with cholelithiasis by RT-PCR. A bicistronic retroviral vector G1Na-MGMT-IRES-MDR1 cDNA was constructed and transfected the packaging cell lines GP + E86 and PA317 by electric performation method, using the medium containing VCR and BCNU for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, cord blood CD34+ cells were enriched with a high-gradient magnetic cell sorting system (MACS), and then transfected repeatedly with supernatant of retrovirus containing human MGMT and MDR1cDNA under stimulation of hemapoietic growth factors. PCR, RT-PCR, Southern blot, Northern blot, Western blot, FACS and MTT assay were used to evaluate the transfer and expression of the double genes in cord blood CD34+ cells. The cDNA encoding MGMT was verified by DNA sequencing and the bicistronic retroviral vector was confirmed by restriction endonuclease analysis. The purity of cord blood CD34+ cells was approximately 92% and recover rate was 75%, the highest titer of recombinant amphotropic retrovirus in the supernatant was up to 5.8 x 10(5) cfu/ml. The efficiency of gene transduction was 18% and 20% tested by colony formation and PCR, respectively. No helper virus was found by both nested PCR and rescue assay. The results showed that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The MTT analysis showed a 4.5 to 7.8-fold increase of resistance of transducted cells to BCNU and P-glycoprotein effluxed drug as compared with the nontransduced cells. This study provided a foundation for ameliorating combination chemotherapy toxicity in tumor clinical trial.

Objective: To study the effect of antisense multidrug resistance-associated protein (MRP) RNA on multidrug resistance (MDR) in the human small cell lung cancer (SCLC) cell line GLC4/ADR, in which the overexpression of MRP gene is discovered., Methods: In using the plasmid pRC/RSV-MRP1 containing complete ORF of MRP as a template, two antisense recombinants targeting at the 5' and 3' regions were constructed with the application of the polymerase chain reaction (PCR) technique. Lipofectamine was conducted to transduce these antisense MRPs into the GLC4/ADR cells. Three clones (the GLC4/ADR-pcDNA3, MO; GLC4/ADR-MRP-5' region, Ma; GLC4/ADR-MRP-3' region, Mb) of transfectants after the selection of G418 were obtained. The expression of MRP protein was detected by the use of the Western blot and the MTT method for determination of chemosensitivity to ADR was used., Results: The antisense MRPs was found to be effectively expressed in the clones, being transfected with two different antisense MRPs. The MRP expression in these transfectants were inhibited at the rates of 14.0% (GLC4/ADR Ma) and 83.0% (GLC4/ADR Mb), respectively. Moreover, decrease in the ADR resistance was observed in the Ma and Mb at the rates of 9.5% and 28.4%. Although the intracellular ADR concentration was increased in these transfectants, the proliferation and cell cycle and their early apoptosis induced by the ADR, indicated no difference between the transfectants and parental cells., Conclusion: It is possible to obtain the effective expression of the MRP antisense structures for the blocking of the mRNA translation in GLC4/ADR cell line and the fragment complementary to the 3'-region of MRP is more effective for the inhibition of the MRP than that related to the 5'-region of MRP. The antisense RNA may be a useful treatment in combination with the conventional chemotherapy for SCLC, in which the MRP overexpression usually occurs.

Objective: To establish the drug-resistant cell line of choriocarcinoma and to study the transfection of the human interleukin 2 (hIL-2) gene into the established drug resistant cell line and investigate the reversal of the multidrug resistance., Methods: The resistant cell line was established by pulse exposed choriocarcinoma cell line JEG-3 to etopside (VP-16) for ten months. The recombinant plasmid containing pcDNA3.1(+)-hIL-2 gene was constructed. The drug resistant cell line was transfected with the constructed plasmid by lipofectin, and the tumor cell colonies containing the IL-2 sequence were selected by genetin. The expression of hIL-2 and drug resistant-related genes was detected by reverse transcript polymerase chain reaction. The chemosensitivity of the gene-transfected tumor cells and the non transfected cell lines to methetraxate, VP-16, kengshengmycine, paclitaxol and 5-fluorouracil was determined by the methyl thiazolyl tetrazolium cytotoxicity assay., Results: The transfected cells expressed human hIL-2 gene, and showed the reversal of multidrug resistance by methyl thiazolyl tetrazolium assay. The transfected cells expressed no multidrug resistance gene-1 (MDR1) on mRNA level. Drug resistance index to VP-16 decreased from 38.7 to 6.0 and 6.1, the index to methetraxate decreased from 14.5 to 2.6 and 2.5, to methetraxate from 13.0 to 2.0., Conclusion: The transfection of hIL-2 gene into the drug resistance cell line of choriocarcinoma can modulate the MDR1 expression on the mRNA level, and reverse the drug resistance.

To explore whether human umbilical cord blood CD34+ cells transduced with human aldehyde dehydrogenase class-1 (ALDH1) and multidrug resistance gene (MDR1) increase resistance to 4-Hyaroxycyclophosphophamide (4-HC) and P-Glycoprotein Effluxed Drugs, a bicistronic Retroviral vector G1Na-ALDH1-IRES-MDR1 was constructed. The vector was transduced into the packaging cell lines GP + E86 and PA317 by LipofectAMINE. Using the medium containing VCR and 4-HC for cloning selection and pingponging supernatant infection between ecotropic producer clone and amphotropic producer clone, we obtained high titer amphotropic PA317 producer clone with the highest titer up to 5.6 x 10(5) CFU/ml. Cord blood CD34+ cells were transfectced repeatedly with supernatant of retrovirus containing human ALDH1 and MDR1cDNA under stimulation of hemopoietie growth factors. PCR, RT-PCR, Southern blot, Northern blot, FACS and MTT method analyses show that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The transgenes recipient cells confered 4- to 7.2-folds stronger resistance to cyclophospsphamede and P-Glycoprotein Effluxes drug in comparison with the nontransduced cells. This study provided a foundation for the application of combination chemotherapy in tumor clinical trial.

Aim: To investigate a feasible synthetic procedure of droloxifene and study on its new bioactivities., Methods and Results: Droloxifene was synthesized using methoxybenzene and phenylacetic acid as starting materials, via Friedel-Crafts acylation, alkylation, demethylation, etherification, Grignard addition, elimination-dehydration, conversing configuration and forming citrate, totally 8 steps, overall yield 14.7% (9.2%). By pharmacological test, droloxifene citrate shows two new bioactivities: (1) obvious effect on reversing the MDR of K562/A02 cells and modulating mdrl, GST pi and TopoII alpha expression. (2) inducing apoptosis in cultured rat luteal cell., Conclusion: The improved synthetic procedure is shorter than the reported method by two steps and has advantages of simple separation, purification and conversion of configuration; easily available starting materials and reagents; concise operation. Two new bioactivities on reversing MDR and inducing apoptosis of luteal cell offered a clue in new drugs research and widened clinic application of droloxifene.

Objective: To investigate whether the hematopoietic cells can be protected from the toxic effect of anticancer agents by transfecting mdr1 gene into bone marrow cells., Methods: The mdr1 gene was transfected into murine and human bone marrow cells by Lipofectin. Expression of mdr1 was assessed by RT-PCR and flow cytometry. The functional activity of mdr1 in transfected cells was examined by rhodamine retention assay. Resistance to chemotherapeutic drugs of human and murine mdr1 gene transfected bone marrow cells was ascertained in vivo and that of murine cells was assessed in vivo in a bone marrow transplantation model., Results: Multidrug resistance 1 gene was successfully transfected into and expressed in murine and human bone marrow cells. The transfected cells were resistant to doxorubicin; Vp-16, vincristine and colchicine. Bone marrow cells transfected with mdr1 gene reconstituted the hematopoietic function and offered resistance to doxorubicin in recipient mice., Conclusion: To transfect mdr1 gene into bone marrow cells is a promissing approach to protect bone marrow cells from the myelosuppressive effect of chemotherapeutic agents.

Objective: To investigate the effect of mdr1 antisense oligodeoxynucleotides (ASON) on reversal of multidrug resistance in ovarian carcinoma cells., Methods: Drug resistance ovarian carcinoma cells SKOV3/mdr1 transducted with human multidrug resistance gene (mdr1) were served as models. The positive rate and function of the mdr1 gene product P-glycoprotein (P-gp) in SKOV3/mdr1 cells after mdr1-ASON (250 micrograms/ml) treatment were determined by flow cytometry and rhodamine 123 efflux trial. Drug resistance of SKOV3/mdr1 cells was also observed by cell colony culture., Results: P-gp positive rate of SKOV3/mdr1 cells after mdr1-ASON treatment was decreased from 38.9% to 21.3% (P < 0.01). Intracellular rhodamine retension in SKOV3/mdr1 cells after mdr1-ASON treatment was increased from 32.1% to 50.7% (P < 0.01). Under effect of Taxol 5 ng/ml, the relative percents of drug-resistant colony in mdr1-ASON treated SKOV3/mdr1 cells and in SKOV3/mdr1 cells was 8% and 63%, respectively, (P < 0.01). Under effect of Doxorubicin 100 ng/ml, the relative percents of drug-resistant colony in mdr1-ASON treated SKOV3/mdr1 cells and in SKOV3/mdr1 cells was 34% and 79%, respectively, (P < 0.01)., Conclusion: mdr1-ASON can reverse multidrug resistance of ovarian carcinoma cell in a certain extent so as to increase chemotherapeutic sensitivity of ovarian carcinoma cells.

Objective: To observe the effect of the transfer of multidrug resistance gene (mdr1) into human hematopoietic progenitor cells (HPC) on the chemoprotection., Methods: Human CD34+ cells served as a target of mdr1 gene transfer. Retroviral vector SF-mdr containing human total length mdr1cDNA was introduced into packing cells GP-envAM12 by liposome-mediated transfection. The mdr1 gene was transduced into human CD34+ cells by retroviral supernatants of packing cells. The integration and expression of the mdr1 gene and its protein (P170) in transduced cells were determined by PCR, RT-PCR, and flow cytometry. The drug resistance of chemotherapy in transduced HPC was determined by culturing colonies., Results: The mdr1 gene was integrated and expressed in transduced CD34+ cells. The efficiency of mdr1 gene transfer was 10%-14%. Compared with untransduced controls, within a certain range of drug concentration, the number of drug-resistant colony in transduced HPC for taxol, doxorubicin, VCR and VP16 were increased by 3.6 +/- 2.1 fold, 2.9 +/- 0.3 fold, 1.9 +/- 0.4 fold, and 3.5 +/- 0.5 fold, respectively., Conclusion: The transfer of the mdr1 gene into human HPC can increase the drug resistance of the transduced cells to corresponding chemotherapeutic drugs that may provide some degree of chemoprotection for HPC.