In vitro and ex vivo evidence for modulation of P-glycoprotein activity by progestins

The well known gender-related differences in drug action may partly be explained by changes in activity and expression of drug metabolising enzymes, but also by modulation of active drug transport systems (e.g. P-glycoprotein, Pgp) by sexual steroids, which is yet not well investigated. Because many women are using hormones (e.g. as oral contraceptives) we investigated the influence of different synthetic progestins on Pgp activity. Pgp inhibition of progesterone, medroxyprogesterone, chlormadinone, cyproterone, levonorgestrel, norethisterone, desogestrel, and norgestimate was measured in vitro in two Pgp over-expressing cell lines (L-MDR1, P388/dx cells) and the corresponding parental cell lines by means of calcein assay, and ex vivo in human peripheral blood mononuclear cells (PBMCs) by rhodamine123 efflux. For most progestins tested, concentrations needed to double baseline fluorescence (f2) in L-MDR1 cells were similar to that of the potent Pgp inhibitor quinidine, whereas levonorgestrel and norethisterone did not reach f2. The results in P388/dx cells essentially confirmed our findings in L-MDR1 cells. Additionally, Pgp inhibitory activity of all progestins tested was also shown ex vivo in PBMCs. The potent Pgp inhibition by several synthetic progestins in vitro and ex vivo suggests that such an interaction might be clinically relevant despite generally low plasma concentrations of progestins. The results may be of particular importance for Pgp substrates, such as protease inhibitors and chemotherapeutic agents, for which intracellular concentrations are critical.     

Activation of latent transforming growth factor beta 1 and inhibition of matrix metalloprotease activity by a thrombospondin-like tripeptide linked to elaidic acid

Impaired wound healing and skin aging are characterized by neutral protease-mediated destruction of matrix macromolecules associated with disturbance in tissue repair. We synthesized a fatty acyl-peptide derivative at aims to simultaneously activate latent TGF-beta through its peptide domain, KFK, and inhibit MMPs through its lipophilic moiety, elaidic acid. Elaidyl-KFK as well as KFK were shown to activate LAP-TGF-beta both in vitro, using a solid phase assay with immobilized LAP-TGF-beta, and ex vivo using human dermal fibroblasts cultures. In both assays, as much as up to 10% of LAP-TGF-beta added could be recovered as active form. KQK, KQFK as well as their lipopeptide counterparts were inactive. Elaidyl-KFK-mediated LAP-TGF-beta activation led to up-regulation of collagen and TIMP-1 production and down regulation of PMA-induced MMP-1 expression in fibroblasts cultures. Those effects could be suppressed by supplementing cell culture medium with blocking TGF-beta antibody. Elaidyl-KFK inhibited MMP-2, MMP-9, MMP-3, MMP-1, in vitro with IC(50) equal to 1.2, 1.0, 0.24 and 8.9 microM, respectively. Its ex vivo inhibitory capacity, as assessed using skin tissue sections, towards the elastin-degrading capacity of MMP-9 was even more pronounced. At a 1 microM concentration, the lipopeptide decreased by up to 80% enzyme activity. Thus, "Lipospondin," i.e. elaidyl-KFK might be considered as a promising model compound to prevent age-associated dermal alterations.     

Effect of metamizol on promyelocytic and terminally differentiated granulocytic cells. Comparative analysis with acetylsalicylic acid and diclofenac

Metamizol is an analgesic and antipyretic agent that can induce agranulocytosis in certain patients. However, its effects on granulocyte viability and differentiation have been poorly evaluated. Here we analysed the effects of metamizol and its active metabolite, 4-methylaminoantipyrine (MAA), on the viability of HL60 promyelocytes and their dimethyl sulphoxide-induced differentiated granulocytes. Metamizol and MAA at 75 microM (above the peak of plasmatic concentration after 2g intake) did not alter granulocytic differentiation of HL60 cells. Only at concentrations above 100 microM, well over the pharmacological range, metamizol-induced apoptosis in about 30% of the HL60 promyelocytes, while HL60-granulocytic terminally differentiated cells were more resistant to this apoptotic action. When the effects of metamizol were compared with those of acetylsalicylic acid (ASA) and diclofenac on cell viability, at equivalent concentrations used in analgesic and antipyretic therapy (75 microM for metamizol, and ASA and 3 microM for diclofenac) their apoptotic effects were similar. Again, the HL60 promyelocytes were more sensitive to apoptosis than granulocytic differentiated cells, as measured by the percentage of sub-G(1) cells detected by flow cytometry and by determination of caspase activity as a function of poly(ADP-ribose) polymerase cleavage. Furthermore, when human blood-derived granulocytes were treated with metamizol, MAA, and ASA at 75 microM or diclofenac at 3 microM, less than 10% of apoptotic granulocytes were detected, whereas at toxicological/suprapharmacological concentrations (10mM), about 90% of granulocytes were apoptotic. These results demonstrate that metamizol, MAA, ASA, and diclofenac, at pharmacological concentrations, neither affect the granulocytic differentiation process nor induce relevant apoptosis on terminally differentiated granulocytes.     

Beta2-adrenoceptor activation inhibits Shiga toxin2-induced apoptosis of renal tubular epithelial cells

Apoptosis is regulated by several pathways, such as caspases, mitogen activated protein kinase (MAPK) and cAMP/cAMP-dependent protein kinase A (PKA) cascade. This study investigated the effect of beta(2)-adrenoceptor activation on Shiga toxin (Stx)2-induced apoptosis in renal tubular cells and the contribution of these signalling pathways. Cultured human adenocarcinoma-derived tubular cells were exposed to Stx2 (64 pg/mL) for 2-24hr following the addition of the beta(2)-adrenoceptor agonist (terbutaline) to the incubation medium. Stx2-induced apoptosis and its amelioration by beta(2)-adrenoceptor activation was confirmed using DNA degradation assays and by flow cytometry for annexin V, mitochondrial membrane potential and caspase(-3 and -7) activity. Exposure of cells to Stx2 for 24hr increased the DNA fragmentation to 11.6+/-0.9%, compared to 3.3+/-0.2% in control cells (P<0.05) but was decreased to approximately 5-7% (P<0.05) in the presence of terbutaline. Furthermore, Stx2-stimulated apoptosis, detected by TUNEL, annexin V and mitochondrial potential, was inhibited by terbutaline (P<0.05) which was prevented by cAMP-PKA inhibitors and a beta(2)-adrenoceptor antagonist. However, inhibition of Stx2-mediated caspase activity by terbutaline was partially blocked by cAMP-PKA inhibitors. On the other hand, p38MAPK inhibition by terbutaline prevented Stx2-induced apoptosis and caspase activity through a cAMP-independent pathway via beta(2)-adrenoceptor. These data indicate that beta(2)-adrenoceptor activation can inhibit Stx2-induced apoptosis of the cells, which may be caused by a reduction in caspase activity through cAMP-PKA activation and the p38MAPK pathway.     

Induction of apoptosis in estrogen dependent and independent breast cancer cells by the marine terpenoid dehydrothyrsiferol

Breast cancer (BCA) represents the highest incidence of death in 35- to 60-year-old women. Above all, hormone unresponsive BCA is still associated with poorer prognosis than hormone receptor expressing malign, mammary tumors. There is a consistent need for effective compounds to treat especially the first variant of this disease. Therefore, we investigated the cytotoxic effects of the marine polyether triterpenoid dehydrothyrsiferol (DT) in four BCA cell lines. Annexin V labeling revealed higher rates of DT-induced apoptosis in hormone insensitive than in estrogen receptor expressing cells. Flow cytometric analysis of combined DNA fragmentation and total DNA labeling allowed us to ascribe apoptotic cells to their cell cycle stage. Although, high cell mortality was detected in mitogen dependent G(1)-phase, time, concentration, and cell line dependent populations of apoptotic cells were also found to be of S-phase and G(2)/M-phase origin. These results suggest that the induction of apoptosis by DT might be transduced through more than one effector pathway. Cell cycle distributions and 5-bromo-2'-deoxyuridine incorporation varied in a treatment dependent manner and differed from control experiments with colchicine and doxorubicin which exclude that DT functions as a mitosis inhibitor. In summary, we propose that DT might be an interesting candidate for an antitumor drug development regimen.     

Photodynamic sterilization of red cells and its effect on contaminating white cells: viability and mechanism of cell death

BACKGROUND: Phthalocyanines are useful sensitizers for photodynamic sterilization of red cell concentrates. Various lipid-enveloped viruses can be inactivated with only limited red cell damage. Because white cells are involved in the immunomodulatory effects of blood transfusions, the study of the effect of photodynamic treatment on these cells is imperative. STUDY DESIGN AND METHODS: White cell-enriched red cell suspensions were photodynamically treated with either the hydrophobic Pc4 (HOSiPcOSi-(CH3)2(CH2)3N(CH3)2) or water-soluble aluminum phthalocyanine tetrasulfonate (AIPCS4) under virucidal conditions. Viability of white cell subpopulations on Days 0, 1, and 4 after treatment was determined by fluorescence-activated cell sorting by flow cytometric analysis of propidium iodide uptake. Apoptosis induction was studied by DNA ladder formation and staining for an early marker of apoptosis (annexin V). RESULTS: Treatment with Pc4 causes a significant decrease in cell viability of all white cells, as shown by prodidium iodide uptake. Monocytes and granulocytes are the most sensitive, and lymphocytes are relatively more resistant. Some of the cells die by apoptosis, which is induced within 30 minutes after treatment. Treatment with AIPCS4 damages only monocytes; other cell populations are not affected. CONCLUSIONS: Physicochemical properties of the photosensitizers partly determine their effect on white cells. Differences in intracellular localization are likely to be responsible for the effects observed.     

Serum supplement, inoculum cell density, and accessory cell effects are dependent on the cytokine combination selected to expand human HPCs ex vivo

BACKGROUND: The prolonged periods of pancytopenia associated with cord blood transplants suggest that in some cases cell numbers may be limiting. The possibility that limiting cell numbers may be overcome and prolonged periods of pancytopenia abrogated by the transplantation of human umbilical cord blood cells expanded ex vivo has led to efforts to define optimal culture conditions for these cells. STUDY DESIGN AND METHODS: Cord blood CD34+ cells were cultured with three cytokine combinations: SCF+G-CSF+GM-CSF+MGDF (SGGM); IL-6+ SCF+MGDF+Flt3-ligand (6SMF); and IL-1+IL-3+IL-6+G-CSF+GM-CSF+SCF+Epo (GFmix). Serum effects, inoculum concentration (cells/mL) seeding density (cell/cm(2)) and accessory cell effects on the expansion of CD34+ cells were determined. RESULTS: Cellular outputs were significantly higher with fetal calf serum (FCS) than with cord blood serum (CBS) or adult group AB serum (ABS) in the presence of 6SMF, however, CBS was as effective as FCS. The best seeding concentrations varied for each of the cytokine combinations, and inoculum densities exceeding 1000 cells per cm(2) proved detrimental for cultures containing GFmix and SGGM. Accessory cell studies indicated that populations expressing the CD33 antigen inhibited the expansion of purified CD34+ cells in the presence of GFmix or SGGM, but not in the presence of 6SMF. CONCLUSION: Serum supplement, inoculum cell concentration, seeding densities, and accessory cell effects are dependent upon the cytokine combination selected to expand cord blood HPCs ex vivo. Thus, each of these measures should be assessed to establish reproducible and reliable conditions for the selection of different cytokine combinations to culture cord blood HPCs.     

Influence of carboxylic acid functionalization on the cytotoxic effects induced by single wall carbon nanotubes on human endothelial cells (HUVEC)

A vast variety of nanomaterials have been developed in the recent years, being carbon nanotubes (CNTs) the ones that have attracted more attention, due to its unique properties which make them suitable for numerous applications. Consequently, it is predicted that tons of CNTs will be produced worldwide every year, being its exposure of toxicological concern. Nanomaterials, once into the body, can translocate from the uptake sites to the blood circulation or the lymphatic system, resulting in distribution throughout the body. Thus, the vascular endothelium can be in contact with them and can suffer from their toxic effects. In this regard, the aim of this work was to investigate the cytotoxicity of single-walled carbon nanotubes (SWCNTs) on human endothelial cells evaluating the influence of acid carboxylic functionalization and also the exposure time (24 and 48 h). Biomarkers assessed were neutral red uptake, protein content, a tetrazolium salt metabolization and cell viability by means of the Trypan blue exclusion test. Cells were exposed to concentrations between 0 and 800 μg/mL SWCNTs for 24 and 48 h. Results have shown that both SWCNTs and carboxylic acid functionalized single-walled carbon nanotubes (COOH-SWCNTs) induce toxic effects in HUVEC cells in a concentration- and time-dependent way. Moreover, the carboxylic acid functionalization results in a higher toxicity compared to the SWCNTs.