【Abstract】 Objective To detect the expression of lung resistance protein (LRP) and investigate its significance in pancreatic carcinoma cell lines (SW1990, PCT-2, PCT-3, PCT-4, Aspc-1, Capan-1, Mia-PaCa-2 and Panc-1). Methods Reverse transcription PCR (RT-PCR) and immunocytochemistry (ICC) were carried out to investigate the expression of LRP. Results LRP mRNA was absent in PCT-2 cell line by RT-PCR. Mild to moderate expression level was found in other pancreatic carcinoma cell lines. PCT-4, Aspc-1 and Panc-1 presented the highest LRP mRNA expression level, in contrast, SW1990, PCT-3, Capan-1 and Mia-PaCa-2 showed moderate LRP mRNA expression. The median value was 0.56±0.33. LRP was further validated by ICC. Absent to weak protein expression of LRP was found in PCT-2 and PCT-3. Overexpressed LRP was present in SW1990, Capan-1 and Aspc-1, furthermore, the highest expression of LRP was found in Panc-1, Mia-PaCa-2 and PCT-4 cell lines. Conclusion All these data showed that LRP might play an important role in multidrug resistance of pancreatic carcinoma.
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.
【Abstract】ObjectiveTo construct a mrp1 expression vector and investigate its biological characteristics in HepG2 cells in vitro. MethodsThe 6.5 kb multidrug resistanceassociated protein （MRP) cDNA obtained from plasmid pGEM-mrp1 was cloned into the pCI-neo mammalian expression vector, which was later transferred into human hepatocarcinoma cell line HepG2 by liposome. Then the HepG2 cells resisting G418 were clustered and proliferated, and the mrp1 mRNA and MRP in these HepG2 cells were detected by means of RT-PCR and FCM respectively. ResultsThe mrp1 expression vector was established successfully, and the stable MDR hepatocarcinoma cell line (HepG2/mrp1) was developed as well. The content of the specific fragment of mrp1 mRNA was (56.8±6.37)% and MRP was 7.89 in the HepG2/mrp1 cells, the corresponding value in HepG2 cells was (9.67±3.26)% and 0.79 respectively. The difference was statistically significant (P＜0.05). ConclusionIt is practicable to establish MDR hepatocarcinoma cell line by transferring mrp1 cDNA into HepG2 cells, which is useful in the research of MDR mechanism.
Objective To predict clinical chemotherapy sensitivity of primary non-small cell lung cancer（NSCLC） by methylthiazal （MTT） tumor chemosensitivity assay method in vitro and detection of multidrug resistance gene1 （MDR1）, and provide reference for clinical individualized treatment. Methods We selected 80 fresh primary NSCLC samples from NSCLC patients who underwent surgical resection in Zibo Central Hospital Affiliated to Binzhou Medical College between January 2009 and December 2011. There were 46 male patients and 34 female patients with their median age of 54 （29 to 81）years. Viable NSCLC cells obtained from malignant tissue were tested for their sensitivity to cisplatin （DDP）, gemcitabine （GEM）, docetaxe （DOC）, etoposide （VP-16） ,and vinorelbine （NVB） using MTT assay in vitro. Fluorescent quantitative reverse transcriptase-polymerase chain reaction （RT-PCR） was used to analysis the expression level of multidrug resistance gene1 （MDR1）. Results After exposure to antitumor drugs, morphologic changes, decrease of metabolic activity, and apoptosis were detected in NSCLC cells. MTT results showed that different individual cancer cells had different chemosensitivity to antitumor drugs, and cancer cells also had different chemosensitivity to different antitumor drugs. Inhibitory rates of cancer cells exposed to DOC, GEM, and VP-16 were significantly higher than those of cancer cells exposed to DDP and NVB （42.5%±9.5%, 40.5%±6.5%, 38.4%±7.6% versus 31.5%±8.5%，32.5%±7.8%, P＜0.05）.The positive rate of MDR1 in tumor tissues was 40.0% （32/80）. The expression of MDR1 was not associated with tumor histological type, degree of differentiation, lymph node metastasis and TNM stage. The expression of MDR1 was associated with resistance to NVB （χ2=5.209，P=0.022），GEM （χ2=4.769，P=0.029），VP-16 （χ2=4.596，P=0.032），and DDP（χ2=6.086，P=0.014）, but not associated with resistance to DOC（χ2=0.430，P=0.512）. Conclusion MTT chemosensitivity assay can effectively predict clinical chemotherapy sensitivity. Detection of MDR1, together with MTT chemosensitivity assay, can more accurately predict NSCLC chemosensitivity and be a guide for individualized chemotherapy of NSCLC.
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 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.
Multidrug resistance (MDR) remains the major obstacle to the success of clinical cancer chemotherapy. P-glycoprotein (P-gp), encoded by the MDR1, is an important part with complex mechanisms associated with the MDR. In order to overcome the MDR of tumors, we in the present experimental design incorporated small interfering RNA (siRNA) targeting MDR1 gene and anticancer drug paclitaxel (PTX) into the solid lipid nanoparticles (SLNs) to achieve the combinational therapeutic effects of genetherapy and chemotherapy. In this study, siRNA-PTX-SLNs were successfully prepared. The cytotoxicity of blank SLNs and siRNA-PTX-SLNs in MCF-7 cells and MCF-7/ADR cells were detected by MTT; and the uptake efficiency of PTX in MCF-7/ADR cells were detected via HPLC method; quantitative real-time PCR and flow cytometry were performed to investigate the silencing effect of siRNA-PTX-SLNs on MDR1 gene in MCF-7/ADR cells. The results showed that PTX loaded SLNs could significantly inhibit the growth of tumor cells, and more importantly, the MDR tumor cells treated with siRNA-PTX-SLNs showed the lowest viability. HPLC study showed that SLNs could enhance the cellular uptake for PTX. Meanwhile, siRNA delivered by SLNs significantly decreased the P-gp expression in MDR tumor cells, thus increased the cellular accumulation of rhodamine123 as a P-gp substrate. In conclusion, the MDR1 gene could be silenced by siRNA-PTX-SLNs, which could promote the growth inhibition efficiency of PTX on tumor cells, leading to synergetic effect on MDR tumor therapy.
Objective To dynamically study the formation of multidrug resistance(MDR) of human hepatocellular carcinoma cell SMMC-7721 induced by Adriamycin (ADM) and the role of multidrug resistance-associated protein(MRP) in its mechanisms.Methods Hepatocellular carcinoma cell SMMC-7721 was cultured in RPMI-1640 medium containing ADM with progressively increased concentration or directly cultured in medium containing different concentrations of ADM. Resistant index of drug-resistant variants of SMMC-7721 cell was determined by drawing cell dosage-reaction curves.Levels of MRP mRNA expression were detected by reverse transcription-polymerase chain reaction(RTPCR). Intracellular rubidomycin(DNR) concentration was examined by flow cytometry(FCM).Results With progressive increasing of ADM concentration in medium resistant index and levels of MRP mRNA expression were correspondingly increased but intracellular DNR concentration was markly reduced. When parental cells were directly cultured in medium containing different concentrations of ADM, the higher the ADM concentration, the higher the level of MRP mRNA expression, but intracellular DNR concentration was kept at the similar high level and most cells died. Conclusion ADM may progressively induce SMMC-7721 cell resistant to multiple chemotherapeutic drugs with reduced intracellular DNR accumulation associated with the overexpression of MRP gene.