Multidrug Resistance-associated Protein Gene Research Articles

Molecular characterization and functional analysis of multidrug resistance-associated genes of Pinewood nematode (Bursaphelenchus xylophilus) for nematicides

Bursaphelenchus xylophilus (Pinewood nematode, PWN) is the causative agent of pine wilt disease (PWD) which caused serious threat to pine forests in the world, especially in East Asia and Western Europe. At present, the control of PWD mainly rely on the massive use of pesticide despite the damage to human health and environmental safety. Developing novel drug targets is the optimized strategy for developing new method to control PWN. In this study, four multidrug resistance-associated protein (MRP) genes containing highly conserved MRP-associated domains were cloned from PWN. The expression patterns of the four Bx-mrps under three different nematicides treatments were studied by quantitative reverse transcription PCR (qRT-PCR) and the function of the four genes in multidrug resistance were also validated by RNA interference (RNAi). Results showed that the expression of Bx-mrp1, Bx-mrp2, Bx-mrp3, and Bx-mrp4 were significantly increased when exposed to different nematicides, wherein, Bx-mrp4 exposed by 4.0 mg/mL of matrine own the highest expression level. The mortality rates of Bx-mrps silenced nematodes revealed significant increase(P < 0.05)under matrine, avermectin, and emamectin benzoate exposure. Specially, Bx-mrp4 exposed with 4.0 mg/mL matrine for 24 h own the highest mortality increase by 18.34%. After RNAi of Bx-mrps, feeding ability of the nematodes were also significantly decreased. These results demonstrate that Bx-mrps were linked to the detoxification process and feeding behavior of PWN. Silencing of Bx-mrps can lead to increased sensitivity of PWN to nematicides and decrease its feeding ability. Bx-mrps are potential new PWN control targets in the future.

Synthesis and biological activity of siRNA and Etoposide with magnetic nanoparticles on drug resistance model MCF-7 Cells: Molecular docking study with MRP1 enzyme

Objective(s): In this work, MRP-1 (Multidrug resistance-associated protein 1) gene expression levels and anticancer activity of siRNA and Etoposide loaded Poly-hydroxybutyrate (PHB) coated magnetic nanoparticles (MNPs) was studied on MCF-7/Sensitive and MCF-7/1000Etoposide resistance cells. For this purpose, PHB covered iron oxide-based magnetic nanoparticles (PHB-MNPs) were prepared by coprecipitation. We used magnetic nanoparticles because they include highly targeted to tumors in vivo cancer therapy. Materials and Methods: Etoposide, anti-cancer drug, was loaded onto the PHB-MNPs. The in vitro cytotoxicity analysis of siRNA and Etoposide-loaded PHB-MNPs was applied on cancer cells. The expression levels of MRP1 related to drug resistance were shown using qRT-PCR. In the present study, we also investigated whether nanoparticle system could be a potential anticancer drug target with molecular docking analyses.Results: The IC50 values of Etoposide on MCF-7/sensitive and MCF-7/1000Eto resistance cells were identified as 50,6 μM and 135,7 μM, respectively. IC50 values of siRNA and Etoposide loaded PHB coated magnetic nanoparticles were determined as 10,18 μM and 39,21 μM on MCF-7 and MCF-7/1000 Eto cells, respectively. According to the gene expression results, MRP1 expression was 4 fold upregulated in MCF-7/1000Eto cells. However, it was about 3 fold downregulated due to the application of siRNA-Etoposide loaded magnetic nanoparticles. Conclusion: According to the docking results, nanoparticle system may be a drug active substance with obtained results. The results of this study demonstrated that siRNA and Etoposide loaded PHB covered iron oxide based magnetic nanoparticles can be a potential targeted therapeutic agent to overcome drug resistance.

Investigation of MRP1 and ABCG2 Gene Expression in Chronic Myeloid Leukemia (CML) Patients

Background: This study evaluated and compared the quantitative expression of multidrug resistance-associated protein 1 (MRP1) and ATP-binding cassette subfamily G member 2 (ABCG2), two Multidrug Resistance (MDR) related genes, in 30 CML patients and 27 normal subjects. Methods: Total RNA was isolated from peripheral blood mononuclear cells (MNCs) using the Trizol reagent. Then cDNAs were synthesized. Gene expression was quantified using Real-Time PCR System. The relative expression of target genes was calculated using the 2-ΔΔCt method. Results: High expression of MRP1 and ABCG2 mRNAs were detected in the patient group. Intra-group comparisons also revealed increased expression of ABCG2 in Accelerated Phase (AP)-Blastic Crisis (BC) patients compared to Chronic Phase (CP) patients. At the same time, the increased expression of MRP1 in AP-BC patients was not statistically significant. Conclusion: Considering the broad spectrum of ATP Binding Cassette (ABC) transporter superfamily substrates, they can play an essential role in cell fate determination. High expression of MRP1 and ABCG2 genes can result in the efflux of therapeutic agents and subsequent reduction in their intracellular concentration. This mechanism finally protects cells from the therapeutic effects of medications. On the other hand, these transporters can export growth factors out of the cell. Such exported molecules may have a growth-inducing effect on adjacent cells. These are the possible mechanisms for the participation of MRP1 and ABCG2 genes in conferring drug resistance to CML cells.

Clinical relevance of the multidrug resistance‑associated protein1 gene in non‑small cell lung cancer: A systematic review and meta‑analysis.

The multidrug resistance‑associated protein1 (MRP1) gene has been found to be consistently overexpressed in the majority of patients with non‑small cell lung cancer(NSCLC). MRP1 is known for its ability to actively decrease intracellular drug concentration, limiting the efficacy of cancer chemotherapy; however, data on the clinical relevance of MRP1 is inconclusive. In the present meta‑analysis, all available published data were combined to provide an updated view on the clinicopathological relevance of MRP1 in patients with NSCLC. A systematic search was conducted to obtain relevant studies published in English, Chinese and Japanese databases. All data from patients with NSCLC who underwent testing for MRP1, by either immunohistochemistry or reverse transcription‑polymerase chain reaction, were extracted and combined for further analysis. Odds ratios(ORs) and 95% confidence intervals(CIs) were calculated for each selected study, with either the fixed‑effects model or the random‑effects model where appropriate. The quality of methodology, heterogeneities and publication bias of the included articles were also analyzed. A total of 36clinical studies involving 3,278patients were included in the study. It was found that the increased expression of the MRP1 gene was associated with the following subgroups of patients: Non‑smokers vs. smokers (OR,2.54; 95%CI, 1.17‑5.54; P=0.019); adenocarcinoma vs. squamous cell carcinoma (OR,1.58; 95%CI, 1.16‑2.17; P=0.004); clinical stageIII‑IV vs. stageI‑II (OR, 1.36; 95%CI, 1.11‑1.66; P=0.003); lymph node metastases(OR, 1.32; 95%CI, 1.09‑1.61; P=0.005); poor response to chemotherapy(OR, 0.41; 95%CI, 0.23‑0.72; P=0.002) and reduced 3‑year survival rate (OR, 0.40; 95%CI, 0.23‑0.68; P=0.001). In conclusion, the findings from this study suggest that increase in MRP1 gene expression is associated with being a non‑smoker, adenocarcinoma, advanced clinical stages and a poor response to chemotherapy in patients with NSCLC. The results from the most extensive and updated data on MRP1 support the requirement for continued investigation into the potential use of MRP1 as a biomarker/clinical indicator for NSCLC.

Differential effects of thiopurine methyltransferase (TPMT) and multidrug resistance-associated protein gene 4 (MRP4) on mercaptopurine toxicity.

Mercaptopurine plays a pivotal role in treatment of acute lymphoblastic leukemia (ALL) and autoimmune diseases, and inter-individual variability in mercaptopurine tolerance can influence treatment outcome. Thiopurine methyltransferase (TPMT) and multi-drug resistant Protein 4 (MRP4) have both been associated with mercaptopurine toxicity in clinical studies, but their relative contributions remain unclear. We studied the metabolism of and tolerance to mercaptopurine in murine knockout models of Tpmt, Mrp4, and both genes simultaneously. Upon mercaptopurine treatment, Tpmt -/- Mrp4 -/- mice had the highest concentration of bone marrow thioguanine nucleotides (8.5pmol/5×106 cells, P=7.8×10-4 compared with 2.7pmol/5×106 cells in wild-types), followed by those with Mrp4 or Tpmt deficiency alone (6.1 and 4.3pmol/5×106 cells, respectively). Mrp4-deficient mice accumulated higher concentrations of methylmercaptopurine metabolites compared with wild-type (76.5 vs. 23.2pmol/5×106 cells, P=0.027). Mice exposed to a clinically relevant mercaptopurine dosing regimen displayed differences in toxicity and survival among the genotypes. The double knock-out of both genes experienced greater toxicity and shorter survival compared to the single knockout of either Tpmt (P=1.7×10-6) or Mrp4 (P=7.4×10-10). We showed that both Tpmt and Mrp4 influence mercaptopurine disposition and toxicity.

Growth of tyrosine kinase inhibitor-resistant Philadelphia-positive acute lymphoblastic leukemia: Role of bone marrow stromal cells.

Human bone marrow stromal cells (hBMSCs) may contribute to the growth of tyrosine kinase inhibitor (TKI)-resistant chronic myelogenous leukemia (CML). However, there are certain differences in biology between CML and Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL). Little is known about the role and mechanism of hBMSCs on the growth of TKI-resistant Ph+ ALL. The current study co-cultured hBMSCs with the TKI-resistant SUP-B15. Next, the proliferation of SUP-B15 was detected using a Cell Counting Kit-8. Additionally, quantitative polymerase chain reaction and flow cytometry were used to detect the expression of the associated genes and proteins. The present study explores the role and mechanism of hBMSCs on the growth of TKI-resistant Ph+ ALL. The current study showed that hBMSCs promoted the proliferation of TKI-resistant Ph+ ALL. This was shown by the increase in cells in the S+G2-M phase of the cell cycle. It was also found that the expression of cyclins A, C, D1 and E was increased. Apoptosis was inhibited through upregulation of anti-apoptotic genes [B-cell lymphoma-2 (BCL-2) and BCL-extra large] and downregulation of apoptotic genes (BCL-XS, BCL-2-associated X protein, and caspases 3, 7 and 9). Expression of the breakpoint cluster region (BCR)-Abelson murine leukemia viral oncogene homolog 1 (ABL) gene, Wnt5a, and Wnt signaling pathway-associated genes (glycogen synthase kinase-3β, β-catenin, E-cadherin and phosphoinositide 3-kinase) and transcription factors (c-myc, ephrin type-B2, fibroblast growth factor 20 and matrix metalloproteinase 7) was also increased. Furthermore, the expression of drug resistance genes (low-density lipoprotein receptor, multidrug resistance-associated protein and multi-drug resistance gene) was increased and the expression of anti-oncogenes (death-associated protein kinase and interferon regulatory factor-1) was decreased. It was concluded that hBMSCs promote the growth of TKI-resistant Ph+ ALL by these aforementioned mechanisms. Therefore, targeting hBMSCs may be a promising approach for preventing the growth of TKI-resistant Ph+ ALL.

Comparison of mercury sulfides with mercury chloride and methylmercury on hepatic P450, phase-2 and transporter gene expression in mice

Zuotai (mainly β-HgS) and Zhusha (also called as cinnabar, mainly α-HgS) are used in traditional medicines in combination with herbs or even drugs in the treatment of various disorders, while mercury chloride (HgCl2) and methylmercury (MeHg) do not have known medical values but are highly toxic. This study aimed to compare the effects of mercury sulfides with HgCl2 and MeHg on hepatic drug processing gene expression. Mice were orally administrated with Zuotai (β-HgS, 30mg/kg), α-HgS (HgS, 30mg/kg), HgCl2 (33.6mg/kg), or MeHg (3.1mg/kg) for 7days, and the expression of genes related to phase-1 drug metabolism (P450), phase-2 conjugation, and phase-3 (transporters) genes were examined. The mercurials at the dose and duration used in the study did not have significant effects on the expression of cytochrome P450 1–4 family genes and the corresponding nuclear receptors, except for a slight increase in PPARα and Cyp4a10 by HgCl2. The expressions of UDP-glucuronosyltransferase and sulfotransferase were increased by HgCl2 and MeHg, but not by Zuotai and HgS. HgCl2 decreased the expression of organic anion transporter (Oatp1a1), but increased Oatp1a4. Both HgCl2 and MeHg increased the expression of multidrug resistance-associated protein genes (Mrp1, Mrp2, Mrp3, and Mrp4). Zuotai and HgS had little effects on these transporter genes. In conclusion, Zuotai and HgS are different from HgCl2 and MeHg in hepatic drug processing gene expression; suggesting that chemical forms of mercury not only affect their disposition and toxicity, but also affect their effects on the expression of hepatic drug processing genes.

Effect of siRNA-Livin on drug resistance to chemotherapy in glioma U251 cells and CD133+ stem cells.

The aim of the present study was to observe the effect of siRNA-Livin on the expression of multidrug resistance-associated protein (MRP) genes in a U251 cell line and U251 stem cells. CD133+ cancer stem cells were identified and isolated from the U251 glioblastoma cells, and morphological observations were used to detect the cell survival conditions. In addition, quantitative polymerase chain reaction was used to detect the mRNA expression levels of Livin, MRP1 and MRP3. Following transfection with the lentivirus containing the siRNA-Livin, the expression of Livin was significantly inhibited in the U251 cells and stem cells (P<0.01). Following temozolomide intervention, the proliferation of the U251 cells and U251 stem cells was restrained, with a lot of cell debris present and the structure of the cell spheres destroyed. The inhibitory effect was more significant following transfection with siRNA-Livin. Prior to siRNA-Livin transfection, the expression of MRP1 presented an increasing trend in the U251 cells and U251 stem cells with increasing drug concentrations and intervention times (P<0.05). Following siRNA-Livin transfection, the expression of MRP1 decreased in the U251 cells and U251 stem cells under the same drug concentration and intervention time (P<0.05), while the expression of MRP3 increased in the U251 stem cells under the same intervention concentration and time (P<0.05). Therefore, siRNA-Livin was shown to decrease the expression of MRP1 in U251 cells and U251 stem cells, increase the expression of MRP3 in U251 stem cells and decrease the proliferation of U251 cells and U251 stem cells. Thus, Livin may be associated with the high expression of MRP1, and siRNA-Livin may be used to lower the expression of MRP1 in order to reduce the drug resistance to chemotherapy in cases of glioblastoma.

Hypoxia-inducible factor-1α induces multidrug resistance protein in colon cancer.

Multidrug resistance is the major cause of chemotherapy failure in many solid tumors, including colon cancer. Hypoxic environment is a feature for all solid tumors and is important for the development of tumor resistance to chemotherapy. Hypoxia-inducible factor (HIF)-1α is the key transcription factor that mediates cellular response to hypoxia. HIF-1α has been shown to play an important role in tumor resistance; however, the mechanism is still not fully understood. Here, we found that HIF-1α and the drug resistance-associated gene multidrug resistance associated protein 1 (MRP1) were induced by treatment of colon cancer cells with the hypoxia-mimetic agent cobalt chloride. Inhibition of HIF-1α by RNA interference and dominant-negative protein can significantly reduce the induction of MRP1 by hypoxia. Bioinformatics analysis showed that a hypoxia response element is located at −378 to −373 bp upstream of the transcription start site of MRP1 gene. Luciferase reporter assay combined with mutation analysis confirmed that this element is essential for hypoxia-mediated activation of MRP gene. Furthermore, RNA interference revealed that HIF-1α is necessary for this hypoxia-driven activation of MRP1 promoter. Importantly, chromatin immunoprecipitation analysis demonstrated that HIF-1α could directly bind to this HRE site in vivo. Together, these data suggest that MRP1 is a downstream target gene of HIF-1α, which provides a potential novel mechanism for HIF-1α-mediated drug resistance in colon cancer and maybe other solid tumors as well.

Down-Regulation of MRP1 Expression in C6/VP16 Cells by Chitosan-MRP1-siRNA Nanoparticles.

High expression of multidrug resistance-associated protein 1 (MRP1) in tumor cells reduces effectiveness of chemotherapy drugs. In this study, we screened MRP1 interfering RNA (MRP1-siRNA) molecules that are able to reverse etoposide (VP16) resistance in multidrug resistance rat glioma cell line C6/VP16, and identified one siRNA molecule that is able to effectively deplete the expression of MRP1 gene and reverse tumor cells resistance to etoposide. Since siRNA instability limits its application in treatment of diseases, we next tested silencing effect of chitosan-MRP1-siRNA nanoparticles and found that the nanoparticles with N:P ratio 175 are able to effectively inhibit MRP1 mRNA and protein expression. Our data demonstrate that chitosan can be used as siRNA carrier for high efficient gene silencing in tumor cells.

Erratum to: Identification of novel rice low phytic acid mutations via TILLING by sequencing

Phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate or InsP6) accounts for 75–85 % of the total phosphorus in seeds. Low phytic acid (lpa) mutants exhibit decreases in seed InsP6 with corresponding increases in inorganic P which, unlike phytic acid P, is readily utilized by humans and monogastric animals. Since InsP6 may also reduce the bioavailability of essential mineral cations, development of lpa seed crops for animal feeds and whole-grain consumers is of significant interest and requires better understanding of the metabolism of InsP6 and the role it plays in other plant processes. To date, well over 20 lpa mutants have been reported in a number of species, most of which have been identified through forward genetic screens. In this study, we used a publicly available rice Targeting of Induced Local Lesions IN Genomes (TILLING) resource to identify four novel lpa mutations, two in one member of the inositol(1,3,4)P3 5/6-kinase (ITPK) gene family (LOC_Os09g34300) and two in a multi-drug resistance-associated protein (MRP) gene (LOC_Os03g04920). The mutations in the ITPK gene resulted in significant reductions in InsP6 (46 and 68 %), while those found in MRP gene were more modest (20 and 30 %). Evaluation of these lines indicates that one of the ITPK mutants (46 % InsP6 reduction) and both MRP mutants are similar to wild-type plants in seed weight, germination, and seedling growth. The four mutants identified here represent new resources for the genetic dissection of phytic acid metabolism in rice and the development of germplasm and strategies for breeding lpa rice varieties.

MRP1 but Not MDR1 Is Associated with Response to Neoadjuvant Chemotherapy in Breast Cancer Patients

A major problem in the treatment of breast cancer is the development of resistance to chemotherapeutic agents. Although the role of multidrug resistance 1 (MDR1) and multidrug resistance associated protein 1 (MRP1) in inducing drug resistance in many cancers has been widely investigated the clinical significance of expression of these genes in breast cancer remains unclear and the data is still controversial. We investigated the expression of MDR1 and MRP1 in breast cancer patients as well as the possible correlation between MDR1 and MRP1 and clinical response to chemotherapy. In the present study, MDR1 and MRP1 gene expression were investigated by real time reverse transcription polymerase chain reaction (RT-PCR) assay in 54 breast cancer tumors and in corresponding adjacent normal tissues before neoadjuvant chemotherapy. The expression level of MDR1 and MRP1 were significantly higher in breast tumors than normal breast tissues. Although a significant relationship was found between the MRP1 expression and response to treatment no association was observed between MDR1 expression and response to treatment. MDR1 and MRP1 expression levels have been shown to be independent of tumor size, histological grade and the status of progesterone or estrogen receptor.

MRP1 but not MDR1 is associated with response to neoadjuvant chemotherapy in breast cancer patients.

A major problem in the treatment of breast cancer is the development of resistance to chemotherapeutic agents. Although the role of multidrug resistance 1 (MDR1) and multidrug resistance associated protein 1 (MRP1) in inducing drug resistance in many cancers has been widely investigated the clinical significance of expression of these genes in breast cancer remains unclear and the data is still controversial. We investigated the expression of MDR1 and MRP1 in breast cancer patients as well as the possible correlation between MDR1 and MRP1 and clinical response to chemotherapy. In the present study, MDR1 and MRP1 gene expression were investigated by real time reverse transcription polymerase chain reaction (RT-PCR) assay in 54 breast cancer tumors and in corresponding adjacent normal tissues before neoadjuvant chemotherapy. The expression level of MDR1 and MRP1 were significantly higher in breast tumors than normal breast tissues. Although a significant relationship was found between the MRP1 expression and response to treatment no association was observed between MDR1 expression and response to treatment. MDR1 and MRP1 expression levels have been shown to be independent of tumor size, histological grade and the status of progesterone or estrogen receptor.

Diallyl sulfide, diallyl disulfide and diallyl trisulfide affect drug resistant gene expression in colo 205 human colon cancer cells in vitro and in vivo

To elevate chemo-resistance of human cancer cells is a major obstacle in the treatment and management of malignant cancers. Diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS) are presented in the Alliaceae family particularly in garlic. Although DAS, DADS and DATS have been shown to exhibit anticancer activities, there is little information on effects of these compounds on drug resistant genes in human colon cancer cells in vitro and in vivo. Herein, we are the first to show that DAS, DADS and DATS at 25μM for 24-h and 48-h incubations promoted expression of drug resistant genes in colo 205 human colon cancer cells. In vitro experiments indicated that DATS promoted gene expression of multidrug resistant 1 (Mdr1) (p<0.05), and DAS and DADS promoted MRP3 gene expression and DATS alone stimulated gene expression of multidrug resistance-associated protein-1 (MRP1) (p<0.05) in colo 205 cells. In vivo studies demonstrated that DADS and DATS induced Mdr1 and MRP1 gene expression (p<0.05). DADS promoted MRP3 gene expression (p<0.05) as well as DADS and DATS increased MRP4 and MRP6 gene expression (p<0.05) in the colo 205 xenograft mice. Based on our in vitro and in vivo results, diallyl polysulfides (DAS, DADS and DATS) affected the gene expression of the multidrug resistance in colo 205 human colon cancer cells in vitro and in vivo.

Polymorphism in multidrug resistance-associated protein gene 3 is associated with outcomes in childhood acute lymphoblastic leukemia

Multidrug resistance-related proteins (MRPs) 2, 3 and 5 are involved in the efflux of drugs used in acute lymphoblastic leukemia (ALL) treatment. Polymorphisms of these genes were investigated for an association with treatment responses in 273 childhood ALL patients. The MRP3 A-189 allele of the regulatory AT polymorphism was associated with reduced event-free survival (P=0.01). The results remained significant after adjustment for multiple comparisons and in the multivariate analysis. Among patients with an event, the A-189 carriers had significantly higher methotrexate plasma levels (P=0.03). MRP3 A-189 also conferred four times higher risk of a relapse in central nervous system (P=0.01). Patients with this allele tended to have lower frequency of thrombocytopenia grade 2 (P=0.06). Gene reporter assay showed that the haplotype tagged by the A-189 had higher promoter activity (P≤0.01). In conclusion, MRP3 A-189 T polymorphism was associated with treatment responses in ALL, likely due to the change in MRP3 efflux.

Over-expression of microRNA169 confers enhanced drought tolerance to tomato

Plant miRNA regulates multiple developmental and physiological processes, including drought responses. We found that the accumulation of Sly-miR169 in tomato (Solanum lycopersicum) was induced by drought stress. Consequently, Sly-miR169 targets, namely, three nuclear factor Y subunit genes (SlNF-YA1/2/3) and one multidrug resistance-associated protein gene (SlMRP1), were significantly down-regulated by drought stress. Constitutive over-expression of a miR169 family member, Sly-miR169c, in tomato plant can efficiently down-regulate the transcripts of the target genes. Compared with non-transgenic plants, transgenic plants over-expressing Sly-miR169c displayed reduced stomatal opening, decreased transpiration rate, lowered leaf water loss, and enhanced drought tolerance. Our study is the first to provide evidence that the Sly-miR169c negatively regulates stomatal movement in tomato drought responses.

Influence of Etoposide on anti-apoptotic and multidrug resistance-associated protein genes in CD133 positive U251 glioblastoma stem-like cells

It has been hypothesized that cancer stem cell is responsible for the refractoriness of glioblastoma therapy. This study is to observe the influence of Etoposide on anti-apoptotic and multidrug resistance-associated protein genes in glioblastoma stem-like cells. U251 glioblastoma cells were cultured and CD133 positive cancer stem-like cells were isolated and identified. Cell counting kit-8 assay, cell morphology and flow cytometry were employed for assaying cell survival condition. Real-time quantitative PCR was chosen for detecting mRNA expression of livin, livinα, livinβ, survivin, MRP1 and MRP3. As results, after Etoposide intervention, the U251 stem-like cells showed more resistant property, more intact morphology and lower apoptotic rate than that in U251 cells ( p < 0.05). It could be found that the expression of livinβ in U251 stem-like cells was significantly higher ( p < 0.05). After Etoposide intervention, only livinα was suppressed markedly ( p < 0.05), while livin expression was not notably decreased with livinβ increased on the contrary ( p < 0.05). MRP1 and MRP3 in U251 stem-like cells were significantly higher than that in cancer cells, and after chemotherapy, the expression of MRP1 increased notably ( p < 0.05). But the expression of survivin and MRP3 did not show these features. In conclusion, after Etoposide intervention glioblastoma stem-like cells showed a stronger resistance to apoptosis and death, and the anti-apoptotic gene livinβ was more related with the high survival rate and MRP1 appeared to be more related with transporting chemotherapeutics out of glioblastoma stem-like cells.

Reversal Effect of Stephania Tetrandra-Containing Chinese Herb Formula SENL on Multidrug Resistance in Lung Cancer Cell Line SW1573/2R120

This research is aimed on reversing multidrug resistance (MDR) of chemotherapy in lung cancer. According to our previous research, chemotherapeutic drugs resistance in lung cancer is mainly due to high expression of multidrug resistance-associated protein (MRP) gene and activation of caspases. The effect of stephania tetrandra-containing Chinese herbal formula, namely Supplement Energy and Nourish Lung (SENL), is effective in enhancing efficacy and reducing toxicity of chemotherapy in lung cancer. However, the underlying mechnism is largely unknown. To understand whether and how SENL herbs function on multidrug-resistance lung cancer cells, we treated a multidrug resistance lung cancer cell line, SW1573/2R120 with SENL herbs alone or together with a chemotherapeutic drug, Adriamycin (ADM). We observed that SENL herbs had a significant synergistic effect with ADM in inhibiting the growth of SW1573/2R120 cells. SENL alone and particularly together with ADM could significantly increase cell apoptotic death via mitochondria- and caspase-dependent pathway. Furthermore, we showed that SENL herbs could reverse drug resistance of lung cancer cells by decreasing MRP expression and increasing accumulation of intracellular ADM, which in turn increase the sensitivity of cancer cells to ADM. Taken together, the mechanism underlying reversal effect of drug resistance by SENL treatment was reported here and further systematical investigation on SENL herbs may lead to solve drug resistance in lung cancer chemotherapy.

Suppression Subtractive Hybridization (SSH)-Based Method for Estimating Cd-Induced Differences in Gene Expression at Cultivar Level and Identification of Genes Induced by Cd in Two Water Spinach Cultivars

The abilities to accumulate cadmium (Cd) are different among cultivars (cv.) in many species. The characteristic of Cd concentration among cultivars is heritable and is probably controlled by genes, but rather limited information about the relevant genes in vegetable crops has been published. In the present study, a suppression subtractive hybridization (SSH) approach was used to identify genes induced by Cd in two water spinach (an important vegetable in southern China) cultivars that differ in Cd accumulation in their edible parts. The two cultivars were cv. Qiangkunqinggu (QK), a low Cd accumulative cultivar and cv. Taiwan 308 (TW), a high Cd accumulative cultivar. In the construction of QK and TW libraries, the plants without Cd treatment were taken as drivers and the plants exposed to 6 mg L(-1) Cd for 24 h as testers. Four hundred clones were sequenced, and 164 nonrepeated sequences (112 from the QK library and 52 from the TW library) were assigned to being functional genes or proteins. A tremendous difference in Cd-induced gene expressions between the two libraries was observed. In the QK library, genes implicated in disease/defense comprised one of the largest sets (20.6%), whereas the proportion was only 8.8% in the TW library. An MT3 gene (Q5), a wound inductive gene (Q22), an antioxidation relevant gene (Q34), a lectin gene (Q45), an f-box family protein gene (Q319), a 20S proteasome subunit gene (T17), a multidrug resistance associated protein gene (T156), and a cationic amino acid transporter gene (T218) were selected to compare semiquantitatively their expression between cv. QK and cv. TW using the RT-PCR method, and obvious differences were detected. The relationships between the identified differences in the expressions of the genes and the Cd accumulation of the two cultivars were discussed, and it was concluded that the SSH approach is useful for finding the difference in expression of Cd-induced gene even at the cultivar level and is applicable in the investigation of the mechanisms of low Cd accumulation.

Polymorphisms in multidrug resistance-associated protein gene 4 is associated with outcome in childhood acute lymphoblastic leukemia

AbstractMethotrexate and 6-mercaptopurine, important components of acute lymphoblastic leukemia treatment, are substrates for multidrug resistance-associated protein MRP4. Eight single nucleotide polymorphisms were analyzed in MRP4 gene, and 4 variants were identified as tagSNPs with frequency more than or equal to 5%. They were investigated for association with treatment responses in 275 children with acute lymphoblastic leukemia. The TC genotype of the regulatory T-1393C polymorphism was associated with better event-free survival (P = .02) and lower methotrexate plasma levels (P = .01). The CA genotype of A934C (Lys304Asn) substitution correlated in contrast with lower event-free survival (P = .02) and higher frequency of high-grade thrombocytopenia (P = .01). Gene reporter assay showed that the promoter haplotype uniquely tagged by the C-1393 allele conferred higher promoter activity compared with remaining haplotypes (P < .001). Further analyses are needed to replicate this pilot study and get closer insight into the functional effect of these polymorphisms.