Influence of Human Bone Marrow Mesenchymal Stem Cells Secretome from Acute Myeloid Leukemia Patients on the Proliferation and Death of K562 and K562-Lucena Leukemia Cell Lineages.

Leukemias are among the most prevalent types of cancer worldwide. Bone marrow mesenchymal stem cells (MSCs) participate in the development of a suitable niche for hematopoietic stem cells, and are involved in the development of diseases such as leukemias, to a yet unknown extent. Here we described the effect of secretome of bone marrow MSCs obtained from healthy donors and from patients with acute myeloid leukemia (AML) on leukemic cell lineages, sensitive (K562) or resistant (K562-Lucena) to chemotherapy drugs. Cell proliferation, viability and death were evaluated, together with cell cycle, cytokine production and gene expression of ABC transporters and cyclins. The secretome of healthy MSCs decreased proliferation and viability of both K562 and K562-Lucena cells; moreover, an increase in apoptosis and necrosis rates was observed, together with the activation of caspase 3/7, cell cycle arrest in G0/G1 phase and changes in expression of several ABC proteins and cyclins D1 and D2. These effects were not observed using the secretome of MSCs derived from AML patients. In conclusion, the secretome of healthy MSCs have the capacity to inhibit the development of leukemia cells, at least in the studied conditions. However, MSCs from AML patients seem to have lost this capacity, and could therefore contribute to the development of leukemia.

Magnolol derivatives as specific and noncytotoxic inhibitors of breast cancer resistance protein (BCRP/ABCG2).

The breast cancer resistance protein (BCRP/ABCG2) transporter mediates the efflux of numerous antineoplastic drugs, playing a central role in multidrug resistance related to cancer. The absence of successful clinical trials using specific ABCG2 inhibitors reveals the urge to identify new compounds to attend this critical demand. In this work, a series of 13 magnolol derivatives was tested as ABCG2 inhibitors. Only two compounds, derivatives 10 and 11, showed partial and complete ABCG2 inhibitory effect, respectively. This inhibition was selective toward ABCG2, since none of the 13 compounds inhibited neither P-glycoprotein nor MRP1. Both inhibitors (10 and 11) were not transported by ABCG2 and demonstrated a low cytotoxic profile even at high concentrations (up to 100 µM). 11 emerged as the most promising compound of the series, considering the ratio between cytotoxicity (IG50) and ABCG2 inhibition potency (IC50), showing a therapeutic ratio (TR) higher than observed for 10 (10.5 versus 1.6, respectively). This derivative showed a substrate-independent and a mixed type of inhibition. The effect of compound 11 on the ABCG2 ATPase activity and thermostability revealed allosteric protein changes. This compound did not affect the expression levels of ABCG2 and increased the binding of the conformational-sensitive antibody 5D3. A docking study showed that 11 did not share the same binding site with ABCG2 substrate mitoxantrone. Finally, 11 could revert the chemoresistance to SN-38 mediated by ABCG2.

Extracellular Vesicles and Cancer Multidrug Resistance: Undesirable Intercellular Messengers?

Cancer multidrug resistance (MDR) is one of the main mechanisms contributing to therapy failure and mortality. Overexpression of drug transporters of the ABC family (ATP-binding cassette) is a major cause of MDR. Extracellular vesicles (EVs) are nanoparticles released by most cells of the organism involved in cell-cell communication. Their cargo mainly comprises, proteins, nucleic acids, and lipids, which are transferred from a donor cell to a target cell and lead to phenotypical changes. In this article, we review the scientific evidence addressing the regulation of ABC transporters by EV-mediated cell-cell communication. MDR transfer from drug-resistant to drug-sensitive cells has been identified in several tumor entities. This was attributed, in some cases, to the direct shuttle of transporter molecules or its coding mRNA between cells. Also, EV-mediated transport of regulatory proteins (e.g., transcription factors) and noncoding RNAs have been indicated to induce MDR. Conversely, the transfer of a drug-sensitive phenotype via EVs has also been reported. Additionally, interactions between non-tumor cells and the tumor cells with an impact on MDR are presented. Finally, we highlight uninvestigated aspects and possible approaches to exploiting this knowledge toward the identification of druggable processes and molecules and, ultimately, the development of novel therapeutic strategies.

ABCB1 and ABCC1 Function during TGF-ß-Induced Epithelial-Mesenchymal Transition: Relationship between Multidrug Resistance and Tumor Progression.

Multidrug resistance (MDR) and induction of metastasis are some of the puzzles encountered during cancer chemotherapy. The MDR phenotype is associated with overexpression of ABC transporters, involved in drug efflux. Metastasis originates from the epithelial-mesenchymal transition (EMT), in which cells acquire a migratory phenotype, invading new tissues. ABC transporters' role during EMT is still elusive, though cells undergoing EMT exhibit enhanced ABCB1 expression. We demonstrated increased ABCB1 expression but no change in activity after TGF-ß-induced EMT in A549 cells. Moreover, ABCB1 inhibition by verapamil increased snail and fibronectin expression, an event associated with upregulation of ABCB1, evidencing coincident cell signaling pathways leading to ABCB1 and EMT-related markers transcription, rather than a direct effect of transport. Additionally, for the first time, increased ABCC1 expression and activity was observed after EMT, and use of ABCC1 inhibitors partially inhibited EMT-marker snail, although increased ABCC1 function translated into collateral sensibility to daunorubicin. More investigations must be done to evaluate the real benefits that the gain of ABC transporters might have on the process of metastasis. Considering ABCC1 is involved in the stress response, affecting intracellular GSH content and drug detoxification, this transporter could be used as a therapeutic target in cancer cells undergoing EMT.

Effect of Polyunsaturated Fatty Acids on Temozolomide Drug-Sensitive and Drug-Resistant Glioblastoma Cells.

Glioblastomas (GBMs) are notoriously difficult to treat, and the development of multiple drug resistance (MDR) is common during the course of the disease. The polyunsaturated fatty acids (PUFAs) gamma-linolenic acid (GLA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) have been reported to improve MDR in several tumors including breast, bladder, and leukaemia. However, the effects of PUFAs on GBM cell MDR are poorly understood. The present study investigated the effects of PUFAs on cellular responses to temozolomide (TMZ) in U87MG cells and the TMZ-resistant (TMZR) cells derived from U87MG. Cells were treated with PUFAs in the absence or presence of TMZ and dose-response, viable cell counting, gene expression, Western blotting, flow cytometry, gas chromatography-mass spectrometry (GCMS), and drug efflux studies were performed. The development of TMZ resistance caused an increase in ABC transporter ABCB1 and ABCC1 expression. GLA-, EPA-, and DHA-treated cells had altered fatty acid composition and accumulated lipid droplets in the cytoplasm. The most significant reduction in cell growth was seen for the U87MG and TMZR cells in the presence of EPA. GLA and EPA caused more significant effects on ABC transporter expression than DHA. GLA and EPA in combination with TMZ caused significant reductions in rhodamine 123 efflux from U87MG cells but not from TMZR cells. Overall, these findings support the notion that PUFAs can modulate ABC transporters in GBM cells.

Comprehensive expression analyses of the ABCG subfamily reveal SvABCG17 as a potential transporter of lignin monomers in the model C4 grass Setaria viridis.

Although several aspects of lignin metabolism have been extensively characterized, the mechanism(s) by which lignin monomers are transported across the plasma membrane remains largely unknown. Biochemical, proteomic, expression and co-expression analyses from several plant species support the involvement of active transporters, mainly those belonging to the ABC superfamily. Here, we report on the genome-wide characterization of the ABCG gene subfamily in the model C4 grass Setaria viridis and further identification of the members potentially involved in monolignol transport. A total of 48 genes encoding SvABCGs were found in the S. viridis genome, from which 21 SvABCGs were classified as full-size transporters and 27 as half-size transporters. Comprehensive analysis of the ABCG subfamily in S. viridis based on expression and co-expression analyses support a role for SvABCG17 in monolignol transport: (i) SvABCG17 is orthologous to AtABCG29, a monolignol transporter in Arabidopsis thaliana; (ii) SvABCG17 displays a similar expression profile to that of lignin biosynthetic genes in a set of different S. viridis tissues and along the elongating internode; (iii) SvABCG17 is highly co-expressed with lignin-related genes in a public transcriptomic database; (iv) SvABCG17displays particularly high expression in the top of the S. viridis elongating internode, a tissue undergoing active lignification; (v) SvABCG17 mRNA localization coincides with the histochemical pattern of lignin deposition; and (vi) the promoter of SvABCG17 is activated by secondary cell wall-associated transcription factors, especially by lignin-specific activators of the MYB family. Further studies might reveal further aspects of this potential monolignol transporter, including its real substrate specificity and whether it works redundantly with other ABC members during S. viridis lignification.

P-glycoprotein and cancer: what do we currently know?

Acquired resistance during cancer treatment is unfortunately a frequent event. There are several reasons for this, including the ability of the ATP-binding cassette transporters (ABC transporters), which are integral membrane proteins, to export chemotherapeutic molecules from the interior of the tumor cells. One important member of this family is the protein known as Permeability Glycoprotein (P-Glycoprotein, P-gp or ABCB1). Its clinical relevance relies mainly on the fact that the inhibition of P-gp and other ABC transporters could result in the reversal of the multidrug resistance (MDR) phenotype in some patients. Recently, other roles apart from being a key player in MDR, have emerged for P-gp. Therefore, this review discusses the relationship between P-gp and MDR, in addition to the possible role of this protein as a biomarker in cancer.

Association between Single Nucleotide Polymorphisms of SULT1A1, SULT1C4, ABCC2 and Phase II Flavanone Metabolites Excretion after Orange Juice Intake.

Citrus fruits and juices are a major source of dietary flavanones, and the regular consumption of these foods is inversely associated with the development of cardiometabolic diseases. However, the biological benefits depend on the bioavailability of these compounds, and previous studies have reported a large interindividual variability in the absorption and excretion of these compounds. Different factors, such as age, gender or genetic polymorphism of genes coding enzymes involved in the metabolism and transport of the flavanones, may explain this heterogeneity. This study aimed to assess the impact of single nucleotide polymorphism of sulfotransferases SULT1A1 and SULT1C4, and ABCC2 transporter genes on excretion of phase II flavanone metabolites in volunteers after 24 h of orange juice intake. Forty-six volunteers ingested a single dose of 500 mL of orange juice and 24-h urine was collected. The hesperetin and naringenin phase II metabolites were quantified in urine, and SNPs in SULT1A1, SULT1C4 and ABCC2 genes were genotyped. A significant (p < 0.05) relationship between the SNPs in these genes and the high excretion of phase II flavanone metabolites were observed. These results identified novel polymorphisms associated with higher absorption of flavanones, which may provide bases for future personalized nutritional guidelines for consuming flavanone-rich foods rich in these nutrients for better benefit from their health properties.

The History of the ABC Proteins in Human Trypanosomiasis Pathogens.

Human trypanosomiasis affects nearly eight million people worldwide, causing great economic and social impact, mainly in endemic areas. T. cruzi and T. brucei are protozoan parasites that present efficient mechanisms of immune system evasion, leading to disease chronification. Currently, there is no vaccine, and chemotherapy is effective only in the absence of severe clinical manifestations. Nevertheless, resistant phenotypes to chemotherapy have been described in protozoan parasites, associated with cross-resistance to other chemically unrelated drugs. Multidrug resistance is multifactorial, involving: (i) drug entry, (ii) activation, (iii) metabolism and (iv) efflux pathways. In this context, ABC transporters, initially discovered in resistant tumor cells, have drawn attention in protozoan parasites, owing to their ability to decrease drug accumulation, thus mitigating their toxic effects. The discovery of these transporters in the Trypanosomatidae family started in the 1990s; however, few members were described and functionally characterized. This review contains a brief history of the main ABC transporters involved in resistance that propelled their investigation in Trypanosoma species, the main efflux modulators, as well as ABC genes described in T. cruzi and T. brucei according to the nomenclature HUGO. We hope to convey the importance that ABC transporters play in parasite physiology and chemotherapy resistance.

Streptococcus mutans glutamate binding protein (GlnH) as antigen target for a mucosal anti-caries vaccine.

BACKGROUND: In recent years, several studies have demonstrated that bacterial ABC transporters present relevant antigen targets for the development of vaccines against bacteria such as Streptococcus pneumoniae and Enterococcus faecalis. In Streptococcus mutans, the glutamate transporter operon (glnH), encoding an ABC transporter, is associated with acid tolerance and represents an important virulence-associated factor for the development of dental caries. RESULTS: In this study, we generated a recombinant form of the S. mutans GlnH protein (rGlnH) in Bacillus subtilis. Mice immunized with this protein antigen elicited strong antigen-specific antibody responses after sublingual administration of a vaccine formulation containing a mucosal adjuvant, a non-toxic derivative of the heat-labile toxin (LTK63) originally produced by enterotoxigenic Escherichia coli (ETEC) strains. Serum anti-rGlnH antibodies reduced adhesion of S. mutans to the oral cavity of naïve mice. Moreover, mice actively immunized with rGlnH were partially protected from oral colonization after exposure to the S. mutans NG8 strain. CONCLUSIONS: Our results indicate that S. mutans rGlnH is a potential target antigen capable of inducing specific and protective antibody responses after immunization. Overall, these observations raise the prospect of the development of mucosal anti-caries vaccines.

Effects of ß-lapachone and ß-nor-lapachone on multidrug efflux transporters and biofilms of Candida glabrata.

Infections caused particularly by Candida glabrata are hard to treat due to the development of antifungal resistance that occurs mainly through the production of efflux pumps and biofilm. Thus, a promising strategy to overcome infections caused by C. glabrata could be to use a substance able to inhibit efflux pumps and eradicate biofilms. Lapachones are natural naphthoquinones that possess a variety of pharmacological properties. Previous studies show that these substances inhibit the growth, virulence factors and efflux pumps of C. albicans. The aim of the present study was to evaluate whether lapachones are able to inhibit efflux pumps related to antifungal resistance in C. glabrata and either prevent biofilm formation or affect mature biofilms. Assays were performed with Saccharomyces cerevisiae strains that overexpress C. glabrata transporters (CgCdr1p and CgCdr2p). One C. glabrata clinical isolate that overexpresses CgCdr1p was also used. Both ß-lapachone and ß-nor-lapachone affected the growth of S. cerevisiae and C. glabrata when combined to fluconazole, and this action was inhibited by ascorbic acid. Both lapachones stimulated ROS production, inhibited efflux activity, adhesion, biofilm formation and the metabolism of mature biofilms of C. glabrata. Data obtained on the present study point to the potential use of ß-lapachone and ß-nor-lapachone as antibiofilm agents and adjuvants on the antifungal therapy related to resistant infections caused by C. glabrata.

A State-of-the-art Review and Prospective Therapeutic Applications of Prenyl Flavonoids as Chemosensitizers against Antifungal Multidrug Resistance in Candida albicans.

Multidrug resistance (MDR) in the opportunistic pathogen Candida albicans is defined as non-susceptibility to at least one agent in two or more drug classes. This phenomenon has been increasingly reported since the rise in the incidence of fungal infections in immunocompromised patients at the end of the last century. After the discovery of efflux pump overexpression as a principal mechanism causing MDR in Candida strains, drug discovery targeting fungal efflux transporters has had a growing impact. Chemosensitization aims to enhance azole intracellular concentrations through combination therapy with transporter inhibitors. Consequently, the use of drug efflux inhibitors combined with the antifungal agent will sensitize the pathogen. As a result, the use of lower drug concentrations will reduce possible adverse effects on the host. Through an extensive revision of the literature, this review aims to provide an exhaustive and critical analysis of the studies carried out in the past two decades regarding the chemosensitization strategy to cope with multidrug resistance in C. albicans. This work provides a deep analysis of the research on the inhibition of drug-efflux membrane transporters by prenylated flavonoids and the interactions of these phytocompounds with azole antifungals as an approach to chemosensitize multidrug-resistant C. albicans strains. We highlight the importance of prenylflavonoids and their particular chemical and pharmacological characteristics that make them excellent candidates with therapeutic potential as chemosensitizers. Finally, we propose the need for further research on prenyl flavonoids as inhibitors of drug-efflux mediated fungal resistance.

ABC-transporter gene expression in ivermectin-susceptible and resistant Haemonchus contortus isolates.

Mammalian efflux transporters of the ATP-binding cassette (ABC) regulate cellular levels of endo- and xenobiotics by transporting molecules across cell membranes and are involved in diverse biological processes. Over-expression of these ABC transporters has been involved in macrocyclic lactone resistance. The main goal of this work was to compare the gene expression of the whole ABC-transporter superfamily in isolates of the sheep nematode Haemonchus contortus with different degrees of susceptibility to ivermectin (IVM). Additionally, the effects of in vivo IVM treatment were evaluated in the resistant isolates. Parasite-free Corriedale lambs were artificially infected with either IVM-susceptible or IVM-resistant H. contortus isolates. The differential expression of ABC transcripts in H. contortus female worms with differential susceptibility to IVM were assessed by RNA-seq. Additionally, the transcription levels of ABC-transporter genes in IVM-resistant adult worms recovered from treated sheep at 12 and 24 h after IVM administration were compared to those of IVM-R worms collected from untreated sheep. The comparative analysis of the ABC-transcripts revealed some minor differences in the expression levels of HCON_00042800 (pgp-3), HCON_00020200.mod (ced-7c), HCON_00085890 (abt-4), HCON_00063000 (pmp-5) and HCON_00116670 (wht-8), indicating that, at transcriptional level, these ABC-genes alone cannot explain resistance in H. contortus. HCON_00130060 (pgp-9.2) was highly differentially expressed in resistant isolates compared to susceptible ones, which agrees with previous reports suggesting that pgp-9 may be one of the most relevant candidates contributing to the multi-genic nature of the IVM resistance trait.

Polyoxovanadates as new P-glycoprotein inhibitors: insights into the mechanism of inhibition.

A promising strategy to overcome multidrug resistance is the use of inhibitors of ABC drug transporters. For this reason, we evaluated the polyoxovanadates (POVs) [V10 O28 ]6- (V10 ), [H6 V14 O38 (PO4 )]5- (V14 ), [V15 O36 Cl]6- (V15 ) and [V18 O42 I]7- (V18 ) as inhibitors of three major multidrug resistance-linked ABC transporters: P-glycoprotein (P-gp), ABCG2 and MRP1. All of the POVs selectively inhibited P-gp. V10 and V18 were the two most promising compounds, with IC50 values of transport inhibition of 25.4 and 22.7 µm, respectively. Both compounds inhibited P-gp ATPase activity, with the same IC50 value of 1.26 µm. V10 and V18 triggered different conformational changes in the P-gp protein with time-dependent inhibition, which was confirmed using the synthesized salt of V10 with rhodamine B, RhoB-V10 . The hydrophilic nature of POVs supports the hypothesis that these compounds target an unusual ligand-binding site, opening new possibilities in the development of potent modulators of ABC transporters.

Comparison of carbohydrate ABC importers from Mycobacterium tuberculosis.

BACKGROUND: Mycobacterium tuberculosis, the etiological agent of tuberculosis, has at least four ATP-Binding Cassette (ABC) transporters dedicated to carbohydrate uptake: LpqY/SugABC, UspABC, Rv2038c-41c, and UgpAEBC. LpqY/SugABC transporter is essential for M. tuberculosis survival in vivo and potentially involved in the recycling of cell wall components. The three-dimensional structures of substrate-binding proteins (SBPs) LpqY, UspC, and UgpB were described, however, questions about how these proteins interact with the cognate transporter are still being explored. Components of these transporters, such as SBPs, show high immunogenicity and could be used for the development of diagnostic and therapeutic tools. In this work, we used a phylogenetic and structural bioinformatics approach to compare the four systems, in an attempt to predict functionally important regions. RESULTS: Through the analysis of the putative orthologs of the carbohydrate ABC importers in species of Mycobacterium genus it was shown that Rv2038c-41c and UgpAEBC systems are restricted to pathogenic species. We showed that the components of the four ABC importers are phylogenetically separated into four groups defined by structural differences in regions that modulate the functional activity or the interaction with domain partners. The regulatory region in nucleotide-binding domains, the periplasmic interface in transmembrane domains and the ligand-binding pocket of the substrate-binding proteins define their substrates and segregation in different branches. The interface between transmembrane domains and nucleotide-binding domains show conservation of residues and charge. CONCLUSIONS: The presence of four ABC transporters in M. tuberculosis dedicated to uptake and transport of different carbohydrate sources, and the exclusivity of at least two of them being present only in pathogenic species of Mycobacterium genus, highlights their relevance in virulence and pathogenesis. The significant differences in the SBPs, not present in eukaryotes, and in the regulatory region of NBDs can be explored for the development of inhibitory drugs targeting the bacillus. The possible promiscuity of NBDs also contributes to a less specific and more comprehensive control approach.

Sensitization to Drug Treatment in Precursor B-Cell Acute Lymphoblastic Leukemia Is Not Achieved by Stromal NF-κB Inhibition of Cell Adhesion but by Stromal PKC-Dependent Inhibition of ABC Transporters Activity.

Cell adhesion to stromal support and the associated intracellular signaling are central to drug resistance, therefore blocking both has been effective in increasing drug sensitization in leukemia. The stromal Ser/Thr protein kinase C (PKC) has been found to be important for conferring protection to leukemic cells. We aimed at elucidating the intracellular signals connected to cell adhesion and to stromal PKC. We found that NF-κB and Akt were up-regulated in mesenchymal stem cells (MSC) after binding of B-cell acute lymphoblastic leukemia (B-ALL) cells. Nevertheless, Akt inhibition did not induce B-ALL cell detachment. In spite of a clear activation of the NF-κB signaling pathway after B-ALL cell binding (up-regulation NF-κB1/2, and down-regulation of the IKBε and IKBα inhibitors) and an important reduction in cell adhesion after NF-κB inhibition, sensitization to the drug treatment was not observed. This was opposite to the PKC inhibitors Enzastaurin and HKPS, a novel chimeric peptide inhibitor, that were able to increase sensitization to dexamethasone, methotrexate, and vincristine. PLCγ1, Erk1/2, and CREB appear to be related to PKC signaling and PKC effect on drug sensitization since they were contra-regulated by HKPS when compared to dexamethasone-treated cells. Additionally, PKC inhibition by HKPS, but not by Enzastaurin, in MSC reduced the activity of three ABC transporters in leukemic cells treated with dexamethasone, a new indirect mechanism to increase sensitization to drug treatment in B-ALL cells. Our results show the validity of targeting the functional characteristic acquired and modulated during cell-to-cell interactions occurring in the leukemic niche.

Transcriptome Analysis Unveils Gln3 Role in Amino Acids Assimilation and Fluconazole Resistance in Candida glabrata.

After Candida albicans, Candida glabrata is one of the most common fungal species associated with candidemia in nosocomial infections. Rapid acquisition of nutrients from the host is important for the survival of pathogens which possess the metabolic flexibility to assimilate different carbon and nitrogen compounds. In Saccharomyces cerevisiae, nitrogen assimilation is controlled through a mechanism known as Nitrogen Catabolite Repression (NCR). NCR is coordinated by the action of four GATA factors; two positive regulators, Gat1 and Gln3, and two negative regulators, Gzf3 and Dal80. A mechanism in C. glabrata similar to NCR in S. cerevisiae has not been broadly studied. We previously showed that in C. glabrata, Gln3, and not Gat1, has a major role in nitrogen assimilation as opposed to what has been observed in S. cerevisiae in which both factors regulate NCR-sensitive genes. Here, we expand the knowledge about the role of Gln3 from C. glabrata through the transcriptional analysis of BG14 and gln3Δ strains. Approximately, 53.5% of the detected genes were differentially expressed (DEG). From these DEG, amino acid metabolism and ABC transporters were two of the most enriched KEGG categories in our analysis (Up-DEG and Down-DEG, respectively). Furthermore, a positive role of Gln3 in AAA assimilation was described, as was its role in the transcriptional regulation of ARO8. Finally, an unexpected negative role of Gln3 in the gene regulation of ABC transporters CDR1 and CDR2 and its associated transcriptional regulator PDR1 was found. This observation was confirmed by a decreased susceptibility of the gln3Δ strain to fluconazole.

Synthesis of new α-Aryl-α-tetralones and α-Fluoro-α-aryl-α-tetralones, preliminary antiproliferative evaluation on drug resistant cell lines and in silico prediction of ADMETox properties.

α-aryl-α-tetralones and α-fluoro-α-aryl-α-tetralones derivatives were synthesized by palladium catalyzed α-arylation reaction of α-tetralones and α-fluoro-α-tetralones, with bromoarenes in moderate to good yields. These compounds were evaluated for their in vitro anti-proliferative effects against human breast cancer and leukemia cell lines with diverse profiles of drug resistance. The most promising compounds, 3b, 3c, 8a and 8c, were effective on both neoplastic models. 3b and 8a induced higher toxicity on multidrug resistant cells and were able to avoid efflux by ABCB1 and ABCC1 transporters. Theoretical calculations of the physicochemical descriptors to predict ADMETox properties were favorable concerning Lipinski's rule of five, results that reflected on the low effects on non-tumor cells. Therefore, these compounds showed great potential for development of pharmaceutical agents against therapy refractory cancers.

Renal and non-renal response of ABC and SLC transporters in chronic kidney disease.

INTRODUCTION: The solute carrier (SLC) and the ATP-binding cassette (ABC) transporter superfamilies play essential roles in the disposition of small molecules (endogenous metabolites, uremic toxins, drugs) in the blood, kidney, liver, intestine, and other organs. In chronic kidney disease (CKD), the loss of renal function is associated with altered function of remote organs. As renal function declines, many molecules accumulate in the plasma. Many studies now support the view that ABC and SLC transporters as well as drug metabolizing enzymes (DMEs) in renal and non-renal tissues are directly or indirectly affected by the presence of various types of uremic toxins, including those derived from the gut microbiome; this can lead to aberrant inter-organ communication. AREAS COVERED: Here, the expression, localization and/or function of various SLC and ABC transporters as well as DMEs in the kidney and other organs are discussed in the context of CKD and systemic pathophysiology. EXPERT OPINION: According to the Remote Sensing and Signaling Theory (RSST), a transporter and DME-centric network that optimizes local and systemic metabolism maintains homeostasis in the steady state and resets homeostasis following perturbations due to renal dysfunction. The implications of this view for pharmacotherapy of CKD are also discussed.

Effect of bile acids on the expression of MRP3 and MRP4: An In vitro study in HepG2 cell line.

INTRODUCTION AND OBJECTIVES: Free and conjugated bile acids (BA's) cannot cross cell membranes; therefore, a particular transport system is required by the cell. Members of the family of ABC (ATP-binding proteins) transporters transfer bile acids in and out of the cell, preventing their accumulation. High intracellular concentrations of bile acids, such as those observed in cholestasis, have been related to oxidative stress and apoptosis, which in many cases are the leading causes of hepatocyte damage. MRP3 and MRP4 (multidrug resistance-associated protein 3 and 4) proteins belong to the ABC subfamily C, and are transporters of the hepatocyte's basolateral membrane with a compensatory role. Both transporters' increased expression constitutes an essential role in the protective and adaptive responses of bile acid overload, such as cholestasis. This work aimed to analyze both transporters' mRNA and protein expression in an in vitro model of cholestasis using HepG2 cell line treated with main bile acids. METHODS: The expression of transporters was investigated through confocal microscopy immunofluorescence, Western Blot, and RT-qPCR after the main bile acids in HepG2 line cells. RESULTS: The results showed the relation between confluence and expression of both transporters in the plasma membrane. MRP3 showed atypical and heterogeneous distribution in this cell line. CDCA (chenodeoxycholic acid) at low concentrations induced the expression of mRNA of both transporters. In contrast, protein expression was induced by CA (cholic acid) at high concentrations. CONCLUSION: Primary bile acids (CDCA and CA) induce overexpression of the MRP4 and MRP3 transporters in the HepG2 cell line.