Oleuropein inhibits migration ability through suppression of epithelial-mesenchymal transition and synergistically enhances doxorubicin-mediated apoptosis in MCF-7 cells

Distinct metastasis is one of the main causes of breast cancer (BC)-related mortality and epithelial-mesenchymal transition (EMT) is a primary step in metastasis dissemination. On the other hand, doxorubicin (DOX) is an effective chemotherapeutic agent against BC; unfortunately, its clinical use is limited by dose-dependent side effects. Therefore, extensive efforts have been dedicated to suppressing metastasis of BC and also to overcome DOX side effects together with keeping its antitumor efficacy. Studies supported the role of oleuropein (OLEU) in reducing DOX-induced side effects besides its antitumor actions. In this study, the antimigratory effect of OLEU was assessed and real-time PCR (RT-PCR) was used to detect OLEU effect on the expression level of EMT markers, in MCF-7 cells. The cytotoxic effect of OLEU and DOX was assessed by MTT assay, whereas the ratio of apoptosis was investigated by flow cytometry. The results showed that migration ability of MCF-7 cells remarkably decreased in OLEU treated group and RT-PCR results showed that OLEU may exert its antimigratory action by suppressing EMT through downregulation of sirtuin1 (SIRT1). Also, the results indicated that both OLEU and DOX were cytotoxic to MCF-7 cells, whereas DOX-OLEU cotreatment led to additive cytotoxicity and apoptosis rate. This study provides evidence regarding the suppressive role of OLEU on MCF-7 cells migration ability through suppression of EMT, and for the first time, it was proposed that SIRT1 downregulation can be involved in the OLEU antimigratory effect. Also, the findings demonstrated that OLEU can reduce DOX-induced side effects by reducing its effective dose.     

Antibody–drug conjugates (ADCs) for cancer therapy: Strategies,challenges, and successes

Targeted delivery of therapeutic molecules into cancer cells is considered as a promising strategy to tackle cancer. Antibody–drug conjugates (ADCs), in which a monoclonal antibody (mAb) is conjugated to biologically active drugs through chemical linkers, have emerged as a promising class of anticancer treatment agents, being one of the fastest growing fields in cancer therapy. The failure of early ADCs led researchers to explore strategies to develop more effective and improved ADCs with lower levels of unconjugated mAbs and more-stable linkers between the drug and the antibody, which show improved pharmacokinetic properties, therapeutic indexes, and safety profiles. Such improvements resulted in the US Food and Drug Administration approvals of brentuximab vedotin, trastuzumab emtansine, and, more recently, inotuzumab ozogamicin. In addition, recent clinical outcomes have sparked additional interest, which leads to the dramatically increased number of ADCs in clinical development. The present review explores ADCs, their main characteristics, and new research developments, as well as discusses strategies for the selection of the most appropriate target antigens, mAbs, cytotoxic drugs, linkers, and conjugation chemistries.     

Radioprotective effect of olanzapine as an anti-psychotic drug against genotoxicity and apoptosis induced by ionizing radiation on human lymphocytes

Molecular Biology Reports - Olanzapine (OLA), is prescribed as an anti-psychotic medicine in schizophrenia patients. In this study, the protective effect of OLA against genotoxicity and...     

Correction to: Effects of Exogenous Spermidine and Elevated CO2 on Physiological and Biochemical Changes in Tomato Plants Under Iso-osmotic Salt Stress

Journal of Plant Growth Regulation - The original version of this article unfortunately contained errors in two authors' names. The given and family names of the authors were incorrectly...     

Initial reaction(s) in biotransformation of CL-20 is catalyzed by salicylate 1-monooxygenase from Pseudomonas sp. strain ATCC 29352

CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) (C(6)H(6)N(12)O(12)), a future-generation high-energy explosive, is biodegradable by Pseudomonas sp. strain FA1 and Agrobacterium sp. strain JS71; however, the nature of the enzyme(s) involved in the process was not understood. In the present study, salicylate 1-monooxygenase, a flavin adenine dinucleotide (FAD)-containing purified enzyme from Pseudomonas sp. strain ATCC 29352, biotransformed CL-20 at rates of 0.256 +/- 0.011 and 0.043 +/- 0.003 nmol min(-1) mg of protein(-1) under anaerobic and aerobic conditions, respectively. The disappearance of CL-20 was accompanied by the release of nitrite ions. Using liquid chromatography/mass spectrometry in the negative electrospray ionization mode, we detected a metabolite with a deprotonated mass ion [M - H](-) at 345 Da, corresponding to an empirical formula of C(6)H(6)N(10)O(8), produced as a result of two sequential N denitration steps on the CL- 20 molecule. We also detected two isomeric metabolites with [M - H](-) at 381 Da corresponding to an empirical formula of C(6)H(10)N(10)O(10). The latter was a hydrated product of the metabolite C(6)H(6)N(10)O(8) with addition of two H(2)O molecules, as confirmed by tests using (18)O-labeled water. The product stoichiometry showed that each reacted CL-20 molecule produced about 1.7 nitrite ions, 3.2 molecules of nitrous oxide, 1.5 molecules of formic acid, and 0.6 ammonium ion. Diphenyliodonium-mediated inhibition of salicylate 1-monooxygenase and a comparative study between native, deflavo, and reconstituted enzyme(s) showed that FAD site of the enzyme was involved in the biotransformation of CL-20 catalyzed by salicylate 1-monooxygenase. The data suggested that salicylate 1-monooxygenase catalyzed two oxygen-sensitive single-electron transfer steps necessary to release two nitrite ions from CL-20 and that this was followed by the secondary decomposition of this energetic chemical.     

Rapid localization of Gag/GagPol complexes to detergent-resistant membrane during the assembly of human immunodeficiency virus type 1

During human immunodeficiency virus type 1 (HIV-1) assembly in HIV-1-transfected COS7 cells, almost all steady-state Gag/Gag and Gag/GagPol complexes are membrane bound. However, exposure to 1% Triton X-100 gives results indicating that while all Gag/GagPol complexes remain associated with the detergent-resistant membrane (DRM), only 30% of Gag/Gag complexes are associated with the DRM. Analysis of the localization of newly synthesized Gag/Gag and Gag/GagPol to the membrane indicates that after a 10-min pulse with radioactive [(35)S]Cys-[(35)S]Met, all newly synthesized Gag/GagPol is found at the DRM. Only 30% of newly synthesized Gag/Gag moves to the membrane, and at 0 min of chase, only 38% of this membrane-bound Gag/Gag is associated with the DRM. During the first 30 min of chase, most membrane-bound Gag/Gag moves to the DRM, while between 30 and 60 min of chase, there is a significant decrease in membrane-bound Gag/Gag and Gag/GagPol. Since the localization of newly synthesized Gag/Gag to the DRM and the interaction of GagPol with Gag both depend upon Gag multimerization, the rapid localization of GagPol to the DRM probably reflects the interaction of all newly synthesized GagPol with the first newly synthesized polymeric Gag to associate with the DRM.     

The interaction between HIV-1 Gag and human lysyl-tRNA synthetase during viral assembly

Human lysyl-tRNA synthetase (LysRS) is a tRNA-binding protein that is selectively packaged into HIV-1 along with its cognate tRNALys isoacceptors. Evidence exists that Gag alone is sufficient for the incorporation of LysRS into virions. Herein, using both in vitro and in vivo methods, we begin to map regions in Gag and LysRS that are required for this interaction. In vitro reactions between wild-type and truncated HIV-1 Gag and human LysRS were monitored using GST-tagged molecules and glutathione-agarose chromatography. Gag/LysRS interaction in vivo was detected in 293FT cells cotransfected with plasmids coding for wild-type or mutant HIV-1 Gag and LysRS, either by monitoring Gag.LysRS complexes immunoprecipitated from cell lysate with anti-LysRS or by measuring the ability of LysRS to be packaged into budded Gag viral-like particles. Based on these studies, we conclude that the Gag/LysRS interaction depends upon Gag sequences within the C-terminal domain of capsid (the last 54 amino acids) and amino acids 208-259 of LysRS. The latter domain includes the class II aminoacyl-tRNA synthetase consensus sequence known as motif 1. Both regions have been implicated in homodimerization of capsid and LysRS, respectively. Sequences falling outside these amino acid stretches can be deleted from either molecule without affecting the Gag/LysRS interaction, further supporting the observation that LysRS is incorporated into Gag viral-like particles independent of its ability to bind tRNALys.     

Parathyroid hormone regulation of type II sodium-phosphate cotransporters is dependent on an A kinase anchoring protein

Parathyroid hormone inhibits sodium-phosphate cotransport in proximal renal tubule cells through activation of several kinases. We tested the hypothesis that the activity of these kinases was coordinated by an A kinase anchoring protein (AKAP) by demonstrating that the type II sodium-phosphate cotransporter (NaPi-4) physically associated with an AKAP and that this association was necessary for regulation of phosphate transport by parathyroid hormone. Immunoprecipitation with anti-NaPi-4 antiserum and glutathione S-transferase pull-down with GST-NaPi-4 showed that NaPi-4 associated with AKAP79, protein kinase A catalytic and regulatory subunits, and the parathyroid hormone receptor in opossum kidney cells. When the regulatory subunit of protein kinase A was uncoupled from the AKAP by a competing peptide, parathyroid hormone lost the ability to inhibit phosphate transport. This result was confirmed by co-transfecting HEK293 cells with the sodium-phosphate cotransporter and wild type AKAP, a mutant AKAP79, or the empty vector. 8-Bromo-cAMP was able to inhibit phosphate transport in cells expressing the wild type AKAP79 but not empty vector or mutant AKAP79. We conclude that parathyroid hormone inhibits proximal renal tubule sodium-phosphate cotransport through a signaling complex dependent upon an AKAP.     

Biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by a rabbit liver cytochrome P450: insight into the mechanism of RDX biodegradation by Rhodococcus sp. strain DN22

A unique metabolite with a molecular mass of 119 Da (C(2)H(5)N(3)O(3)) accumulated during biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by Rhodococcus sp. strain DN22 (D. Fournier, A. Halasz, J. C. Spain, P. Fiurasek, and J. Hawari, Appl. Environ. Microbiol. 68:166-172, 2002). The structure of the molecule and the reactions that led to its synthesis were not known. In the present study, we produced and purified the unknown metabolite by biotransformation of RDX with Rhodococcus sp. strain DN22 and identified the molecule as 4-nitro-2,4-diazabutanal using nuclear magnetic resonance and elemental analyses. Furthermore, we tested the hypothesis that a cytochrome P450 enzyme was responsible for RDX biotransformation by strain DN22. A cytochrome P450 2B4 from rabbit liver catalyzed a very similar biotransformation of RDX to 4-nitro-2,4-diazabutanal. Both the cytochrome P450 2B4 and intact cells of Rhodococcus sp. strain DN22 catalyzed the release of two nitrite ions from each reacted RDX molecule. A comparative study of cytochrome P450 2B4 and Rhodococcus sp. strain DN22 revealed substantial similarities in the product distribution and inhibition by cytochrome P450 inhibitors. The experimental evidence led us to propose that cytochrome P450 2B4 can catalyze two single electron transfers to RDX, thereby causing double denitration, which leads to spontaneous hydrolytic ring cleavage and decomposition to produce 4-nitro-2,4-diazabutanal. Our results provide strong evidence that a cytochrome P450 enzyme is the key enzyme responsible for RDX biotransformation by Rhodococcus sp. strain DN22.     

Biotransformation of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) by denitrifying Pseudomonas sp. strain FA1

The microbial and enzymatic degradation of a new energetic compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), is not well understood. Fundamental knowledge about the mechanism of microbial degradation of CL-20 is essential to allow the prediction of its fate in the environment. In the present study, a CL-20-degrading denitrifying strain capable of utilizing CL-20 as the sole nitrogen source, Pseudomonas sp. strain FA1, was isolated from a garden soil. Studies with intact cells showed that aerobic conditions were required for bacterial growth and that anaerobic conditions enhanced CL-20 biotransformation. An enzyme(s) involved in the initial biotransformation of CL-20 was shown to be membrane associated and NADH dependent, and its expression was up-regulated about 2.2-fold in CL-20-induced cells. The rates of CL-20 biotransformation by the resting cells and the membrane-enzyme preparation were 3.2 +/- 0.1 nmol h(-1) mg of cell biomass(-1) and 11.5 +/- 0.4 nmol h(-1) mg of protein(-1), respectively, under anaerobic conditions. In the membrane-enzyme-catalyzed reactions, 2.3 nitrite ions (NO(2)(-)), 1.5 molecules of nitrous oxide (N(2)O), and 1.7 molecules of formic acid (HCOOH) were produced per reacted CL-20 molecule. The membrane-enzyme preparation reduced nitrite to nitrous oxide under anaerobic conditions. A comparative study of native enzymes, deflavoenzymes, and a reconstituted enzyme(s) and their subsequent inhibition by diphenyliodonium revealed that biotransformation of CL-20 is catalyzed by a membrane-associated flavoenzyme. The latter catalyzed an oxygen-sensitive one-electron transfer reaction that caused initial N denitration of CL-20.