Drug resistance gene expression and chemotherapy sensitivity detection in Chinese women with different molecular subtypes of breast cancer

Objective:The aim of the study was to identify specific chemosensitivity drugs for various molecular subtypes of breast tumors in Chinese women,by detecting the expression of drug resistance genes and by using the drug sensitivity test on different molecular subtypes of breast cancers.Methods:The expression of drug resistance genes including Topo Ⅱ,GST-π,P-gp,LRP,and CD133 were detected with immunohistochemistry in a tissue microarray.Drug sensitivity tests included those for paclitaxel,epirubicin,carboplatin,vinorelbine,and fluorouracil and were conducted on primary cancer tissue cells and cell lines,including the T47 D,BT-474,and MDA-MB-231 cells and human breast cancer xenografts in nude mice.Results:The different drug resistant genes Topo Ⅱ,GST-π,P-gp,and LRP were differentially expressed among different molecular subtypes of breast cancers(P<0.05).Positive expression of CD133 was highest in basal-like breast cancer(P<0.05).Kaplan-Meier survival analysis showed that positive expressions of Topo Ⅱ and CD133 both correlated with shorter disease-free survival(DFS)(P<0.05)and overall survival(P<0.05),and positive expression of LRP correlated only with shorter DFS(P<0.05).BT-474 showed chemosensitivity to paclitaxel and epirubicin,while MDA-MB-231 showed chemosensitivities to paclitaxel,epirubicin,carboplatin,and fluorouracil(T/C≤50%).The basal-like and HER2+breast cancer primary cells showed chemosensitivities to paclitaxel and epirubicin with significant differences compared with luminal breast cancer primary cells(P<0.05).Conclusions:The differential expression of drug resistance genes and the differential chemosensitivities of drugs in different molecular subtype of breast cancers suggested that individual treatment should be given for each type of breast cancer.

Liposome-mediated Functional Expression of Multiple Drug Resistance Gene in Human Bone Marrow CD34^+ Cells

Summary: The expression and functional activity of multiple drug resistance (MDR1) gene in human normal bone marrow CD34+ cells was observed. Human normal bone marrow CD34+ cells were enriched with magnetic cell sorting (MACS) system, and then liposome-mediated MDR1 gene was transferred into bone marrow CD34+ cells. Fluorescence-activated cell sorter was used to evaluate the expression and functional activity of P-glycoprotein (P-gp) encoded by MDR1 gene. It was found that the purity of bone marrow CD34+ cells was approximately (91±4.56) % and recovery rate was (72.3±2.36) % by MACS. The expression of P-gp in the transfected CD34+cells was obviously higher than that in non-transfected CD34+ cells. The amount of P-gp in non-transfected CD34+ cells was (11.2±2.2) %, but increased to (23.6±2.34) % 48 h after gene transfection (P<0.0l). The amount of P-gp was gradually decreased to the basic level one week later. The accumulation and extrusion assays showed that the overexpression of P-gp could efflux Rh-123 out of cells and there was low fluorescence within the transfected cells. The functional activity of P-gp could be inhibited by 10 μg/ml verapamil. It was suggested that the transient and highly effective expression and functional activity of P-gp could be obtained by liposome-mediated MRD1 transferring into human normal bone marrow CD34+ cells.

Reversing drug resistance in the ovarian carcinoma cell line SKOV3/mdr1 in vitro by antisense oligodeoxynucleotides

Objective To investigate the effect of multidrug resistance gene 1 (mdr1) antisense oligodeoxynucleotides (ODNs) on reversing multidrug resistance in the drug resistant ovarian carcinoma cell line SKOV3/mdr1. Methods The ovarian carcinoma cell line SKOV3 transducted with a human multidrug resistance gene (mdr1) served as the drug resistant model (SKOV3/mdr1). The mdr1 antisense ODNs was transfected into SKOV3/mdr1 cells while mediated by lipofectamine. Reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the expression and the amount of the mdr1 mRNA in the cells. The positive rate and function of the mdr1 gene product P-glycoprotein (Pgp) in the mdr1 antisense ODNs treated SKOV3/mdr1 cells were determined by flow cytometry and rhodamine 123 efflux. Drug resistance in the SKOV3/mdr1 cell line was observed by MTT assay and cell colony culture. Results The mdr1 mRNA level was decreased to about 60% of that of β-actin after mdr1 antisense ODNs treatment. The Pgp positive rate of mdr1 antisense ODNs treated SKOV3/mdr1 cells decreased from 100% to 52.6% (P<0.01). The intracellular rhodamine 123 retention was increased from 9.1% to 33.8% (P<0.01). The chemoresistance to taxol decreased to 58% of SKOV3/mdr1 with mdr1 antisense ODN treatment. Compared with SKOV3/mdr1 cells in the control group, under a certain range of drug concentrations, the number of drug resistance colonies in mdr1 antisense ODNs treated SKOV3/mdr1 cells for taxol and doxorubicin decreased by 8.6±0.8 fold and 3.1±0.6 fold, respectively. Some non-specific functions during oligodeoxyncleotide treatment was also detected. Conclusion mdr1 expression in the SKOV1/mdr1 cell line was partially inhibited after mdr1 antisense ODNs treatment at the mRNA and protein level, increasing the chemotherapy sensitivity of this drug resistant ovarian carcinoma cell line.

The status of drug resistance and ampC gene expression in Enterobacter cloacae

Objective To investigate the status of the drug resistance and the ampC gene expression of Enterobacter cloacae . Methods Disk diffusion tests were made for detecting the susceptibility of antimicrobial agents against Enterobacter cloacae . AmpC gene was amplified by polymerase chain reaction (PCR) and verified by DNA sequencing. AmpC gene expression was analyzed according to antimicrobial agent sensitive phenotype. Results The sensitivity rates of 144 strains to imipenam,cefepime and cefoperazone/sulbactam were 98.61%,65.97% and 63.89%,respectively. The sensitivity rates of 144 strains to other antimicrobial agents were lower. Among the 144 strains 120 were found to be positive by PCR for ampC. The PCR product showed high homology to the GenBank ampC sequence. Stably derepressed strains,hyperinducible strains and unexpressing or lower level expressing strains accounted for 30.0% (36/120),37.5% (45/120),and 32.5% (39/120),respectively. Fifty-six out of 120 strains (46.67%) also produced extended spectrum β-lactamases (ESBLs). The hyperinducible strains were highly sensitive to all the antimicrobial agents except amoxicillin/clavulanic acid and cefuroxime,while the stably derepressed strains were only sensitive to imipenam and cefepime. However,sensitivity to cefepime decreased if the strains also produced ESBLs. Conclusions The durg resistant status of Enterobacter cloacae is severe. Clearing out the expressive status of ampC gene will be helpful in selection of antimicrobial agents in the treatment of clinical infection.

Antiepileptic drug-induced multidrug resistance P-glycoprotein overexpression in astrocytes cultured from rat brains

Background Intractable epilepsy may be due to multidrug resistance induced by conventional antiepileptic drugs. The phenomenon is sometimes associated with an overexpression of multidrug resistance gene 1 (MDR 1). The purpose of this study was to determine if the overexpression of MDR 1 could be induced in astrocytes from rat brains in vitro using antiepileptic drugs.Methods Astrocyte cell cultures from postnatal Wistar rats (within 24 hours of birth) were established. Different concentrations of the antiepileptic drugs phenytoin, phenobarbital, carbamazepine, and valproic acid were added to the cultures for 10, 20, or 30 days. The expression of P-glycoprotein (Pgp), the protein product of MDR 1, was investigated with immunocytochemistry. Results Less than 5% of normal, untreated astrocytes had detectable Pgp staining at any time point. Phenytoin, phenobarbital, carbamazepine, and valproic acid induced the overexpression of Pgp in astrocytes in a dose- and time-dependent manner. Significantly higher levels of Pgp staining were detected at therapeutic concentrations of certain antiepileptic drugs (20 μg/ml phenobarbital, 40 μg/ml phenobarbital, and 20 μg/ml phenytoin) on day 30. Upregulation of Pgp was detected when using higher concentrations of phenytoin, phenobarbital, and valproic acid on day 20 and when using higher concentrations of any of the four antiepileptic drugs on day 30. Conclusions Treatment with antiepileptic drugs may contribute to the overexpression in astrocytes of MDR 1 and its protein product, Pgp. The mechanism leading to MDR must be considered in patients undergoing long-term treatment with antiepileptic drugs.

Effect of Artemisinin Combined with Glucocorticoid on the Expressions of Glucocorticoid Receptor α mRNA,Glucocorticoid Receptor β mRNA and P300/CBP Protein in Lupus Nephritis Mice

Objective：To investigate the therapeutic effects and mechanisms of using artemisinin（Art） combined with glucocorticoid（GC） to treat lupus nephritis（LN） mice.Methods：Forty hybrid female mice were randomly and equally divided into four groups with the method of random number table：control group,model group,prednisone group administrated with 6.45 mg/（kg·d） prednisone suspension,and Art＋prednisone group administrated with 150 mg/（kg·d） Art suspension and 3.225 mg/（kg·d） prednisone suspension.A mice model of LN was established by injection with living lymph cell suspension.The changes of urine protein/24h,the expressions of GC receptorα（GRα） mRNA,GC receptorβ（GRβ） mRNA in peripheral blood mononuclear cells（PBMCs）,and transcriptional coactivator P300/CBP protein in renal tissue were measured.Results： Compared with the model group,the treatment groups had significant decrease in urine protein/24 h,and renal pathological lesion（P0.01）.In the same groups,the expression of transcriptional coactivator P300/CBP protein in renal tissue and GRαmRNA were significantly increased,and GRβmRNA expression was significantly decreased（P0.01）.And the Art＋prednisone group has a better therapeutic effect than the prednisone group （P0.01）.Conclusions：Art has therapeutic sensitization effects on GC in the LN mice.The underlying mechanism could be correlated with the effect of Art on the increase of the expressions of GRαmRNA and transcriptional coactivator P300/CBP protein in renal tissue and on the decrease of the expression of GRβmRNA in PBMCs.