Celecoxib up regulates the expression of drug efflux transporter ABCG2 in breast cancer cell lines

Elevated expression of the drug efflux transporter ABCG2 seems to correlate with multidrug resistance of cancer cells. Specific COX-2 inhibitor celecoxib has been shown to enhance the sensitivity of cancer cells to anticancer drugs. To clarify whether ABCG2 inhibition is involved in the sensitizing effect of celecoxib, we investigated whether the expression of ABCG2 in breast cancer cell lines, could be modulated by celecoxib. The expression of the multidrug resistant gene (ABCG2) at mRNA and protein level was detected by real-time quantitative reverse transcription-polymerase chain reaction and flow cytometry analysis, respectively. Among three human breast cancer cell lines ABCG2 and COX-2 were highly expressed in MCF7-MX and MDA-MB-231 cells, respectively. The COX-2 inhibitor celecoxib up-regulated the expression of ABCG2 mRNA in MCF-7 and MCF7-MX cells, which was accompanied by increased ABCG2 protein expression. While celecoxib was able to block the 12-O-tetradecanoylphorbol-13-acetate (TPA)-mediated increase in COX-2 expression in MDA-MB-231 cells, it increased the expression of ABCG2 up to 4.27 times to the control level at mRNA level and with less intensity at protein level. Our findings provide evidence that celecoxib up-regulates ABCG2 expression in human breast cancer cells and proposed that ABCG2 is not involved in chemosensitizing effects of celecoxib

High-throughput bioaccumulation, biotransformation, and production of silver and selenium nanoparticles using genetically engineered Pichia pastoris

A genetically modified Pichia pastoris strain overexpressing a metal-resistant variant of cytochrome b5 reductase enzyme was developed for silver and selenium biosorption and for nanoparticle production. The maximum recombinant enzyme expression level was approximately 31 IU/ml in the intercellular fluid after 24 h of incubation, and the capacity of the recombinant biomass for the biosorption of silver and selenium in aqueous batch models were measured as 163.90 and 63.71 mg/g, respectively. The ions were reduced in the presence of enzyme, leading to the formation of stable 70–180 nm metal nanoparticles. Various instrumental analyses confirmed the well-dispersed and crystalline nature of the spherical nanometals. The purified silver and selenium nanoparticles exhibited at least 10-fold less cytotoxicity toward HDF, EPG85–257, and T47D cells than silver nitrate and selenium dioxide. These results revealed that the engineered Pichia strain is an eco-friendly, rapid, high-throughput, and versatile reduction system for nanometal production

Human cytochrome b5 reductase: structure, function, and potential applications

Cytochrome b5 reductase is a flavoprotein that is produced as two different isoforms that have different localizations. The amphipathic microsomal isoform, found in all cell types with the exception of erythrocytes, consists of one hydrophobic membrane-anchoring domain and a larger hydrophilic flavin catalytic domain. The soluble cytochrome b5 reductase isoform, found in human erythrocytes, is a truncated protein that is encoded by an alternative transcript and consists of the larger domain only. Cytochrome b5 reductase is involved in the transfer of reducing equivalents from the physiological electron donor, NADH, via an FAD domain to the small molecules of cytochrome b5. This protein has received much attention from researchers due to its involvement in many oxidation and reduction reactions, such as the reduction of methemoglobin to hemoglobin. Autosomal cytochrome b5 reductase gene deficiency manifests with the accumulation of oxidized Fe+3 and recessive congenital methemoglobinemia in humans. In this article, we provide a comprehensive overview of the structure and function of cytochrome b5 reductase from different eukaryotic sources and its potential use in the food industry, biosensor, and diagnostic areas

The role of Olea Europaea L. Fruit on A2780, A172 and HFFF2 proliferation

Olea europaea L. commonly known as olive has been traditionally used for the prevention and treatment of many diseases since ancient times. Olive has been reported to possess a broad spectrum of pharmacological properties. In the present study, we investigated the activity of aqueous extract of Olea europaea L. fruit at various concentrations on A2780, A172, and HFFF2 cell lines proliferation by MTT assay. Aqueous extract of olive significantly increased cell proliferation in a dose dependent manner in the cell lines. It has been previously reported that olive has chemoproventive and anti-tumor effects. These disagreements can be explained by differences in cell line properties, type of olive and different solvents in the extracts. However, further investigation is needed to clarify the exact role of olive in cell proliferation and cancer. In this study fruit extract of Olea europaea L. showed more activatory effects on A2780 cell line in comparison with A172 and HFFF2. These differences in the activatory effects may be related to the activation of different signaling pathways in different cell lines. © 2016, Iranian Association of Pharmaceutical Scientists. All rights reserved

An introduction to tissue engineering and the most widely used scaffolds

Background: In today’s world, humankind is exposed upon a wide spectrum of diseases and tissue damages, which some of them are untreatable with current medical approaches. The untreated damaged tissues encompasses a widespread of destroyed parts with loss function in which natural repair mechanisms are not able to reconstruct them. Therefore, remedy for these lesions is related to a branch of medical sciences called regenerative medicine. One of the tools in regenerative medicine is transplantation of tissue-like structures via tissue engineering. We searched several databases such as PubMed, Scientific Information Database (SID), Springer, Medline, Magiran, ScienceDirect, and Sivilica, and used Google Scholar search engine to find the articles in this issue. Different researches and clinical results show that with the help of tissue engineering, structures similar to natural tissues for repair can be designed. These structures are made up of three parts of scaffold, cell, and growth factors. In the construction of these structures, the design of ideal scaffold with the desired properties and mechanical strength is important, depending on the type of material and method of its construction. Regenerative medicine and tissue engineering are successful and necessary in repairing or replacing damaged tissues

Potential role of cyclooxygenase-2 on the regulation of the drug efflux transporter ABCG2 in breast cancer cell lines

ABCG2 (BCRP) implicated as a member of the multidrug resistance (MDR) proteins in tumors, mediating efflux of a wide spectrum of anticancer drugs. In recent years, there has been an increasing tendency toward the exploring of the potential link between cyclooxygenase-2 (COX-2) expression and development of multidrug resistance phenotype in patients with cancer. The aim of this study was to investigate the role of the COX-2 in modulating drug efflux by ABCG2 in a group of breast cancer cell lines. The cytotoxicity of COX-2 inducer (TPA, tetradecanoyl phorbol acetate) and its inhibitor (celecoxib) was determined by an MTT assay. ABCG2 activity was measured by flow cytometric mitoxantrone efflux assay. TPA exhibited very little inhibitory activity in all cell lines, while long-term treatment with celecoxib significantly inhibited the growth of all cell lines. Furthermore, using mitoxantrone efflux assay was shown that TPA could increase ABCG2 activity in all the cell lines with the greatest stimulatory effects in MCF7-MX (more than 6 times the control level). It seemed that celecoxib inverted the effects of TPA on ABCG2 activity. This was more obvious in MCF7-MX. The results suggest a probable causal link between COX-2 and ABCG2 activity. The use of celecoxib for adjuvant therapy in cancer treatment may contribute to decreased resistance to chemotherapeutic drugs transported by ABCG2 Potential role of cyclooxygenase-2 on the regulation of the drug efflux transporter ABCG2 in breast cancer cell lines. Available from: https://www.researchgate.net/publication/43346615_Potential_role_of_cyclooxygenase-2_on_the_regulation_of_the_drug_efflux_transporter_ABCG2_in_breast_cancer_cell_lines [accessed Dec 11 2017]

Dexamethasone downregulates BCRP mRNA and protein expression in breast cancer cell lines.

It is hypothesized that anti-inflammatory drugs regulate breast cancer resistance protein (BCRP) expression. Hence, we examined the effects of indomethacin and dexamethasone on BCRP expression in MCF cells. For evaluation of BCRP mRNA expression, relative quantitative PCR and comparative C1 method was exploited. BCRP protein expression was measured flow cytometrically with the monoclonal antibody (mAb) BXP-21. Dexamethasone showed a dose-independent and a time-dependent effect on decreasing the mRNA level of BCRP gene in comparison with control in MCF-7 and MCF-7/MX breast cancer cell lines, whereas no changes were noted in the presence of indomethacin. The level of BCRP protein, expressed as a ratio of the corresponding control, was decreased in dexamethasone-treated MCF-7/MX cells. These results could be of great importance when combination therapy protocols with cytotoxic agents and dexamethasone regimens are considered in breast cancer patients

Evaluation of indomethacin and dexamethasone effects on BCRP-mediated drug resistance in MCF-7 parental and resistant cell lines.

Breast cancer resistance protein is a member of the ATP-binding cassette transporter G family that extrudes xenotoxins from cells, mediating drug resistance, and has been recognized as a major cause of failure of various carcinoma chemotherapies. In this study, the modulatory effects of dexamethasone and indomethacin on the cell cytotoxicity of mitoxantrone and on the BCRP protein activity in breast cancer cell lines were examined. MCF cells were seeded at 1 x 10(4) cells per well in 96-well flat-bottomed microplates for 48 hours and treated with increasing doses of dexamethasone, indomethacin, and novobiocin alone or preincubated with increasing doses of the drugs and then coexposed to mitoxantrone. Cell viability was measured after 1-4 days, using the MTT assay. BCRP activity was determined flow cytometrically by measuring mitoxantrone accumulation in the absence and presence of the inhibitor, novobiocin. Cotreatment of mitoxantrone with different concentrations of dexamethasone and indomethacin sensitized parental and resistant MCF-7 cells to mitoxantrone cytotoxicity. Dexamethasone increased the accumulation of mitoxantrone in the MCF-7/MX cell line, indicating an inhibition of BCRP. In spite of increased levels of mitoxantrone cytotoxicity in the presence of indomethacin, the accumulation of mitoxantrone was not increased in indomethacin-treated MCF cells