HbF reactivation in sibling BFU-E colonies: synergistic interaction of kit ligand with low-dose dexamethasone

Mechanisms underlying fetal hemoglobin (HbF) reactivation in stress erythropoiesis have not been fully elucidated. We suggested that a key role is played by kit ligand (KL). Because glucocorticoids (GCs) mediate stress erythropoiesis, we explored their capacity to potentiate the stimulatory effect of KL on HbF reactivation, as evaluated in unilineage erythropoietic culture of purified adult progenitors (erythroid burst-forming units [BFU-Es]). The GC derivative dexamethasone (Dex) was tested in minibulk cultures at graded dosages within the therapeutical range (10−6 to 10−9M). Dex did not exert significant effects alone, but synergistically it potentiated the action of KL in a dose-dependent fashion. Specifically, Dex induced delayed erythroid maturation coupled with a 2-log increased number of generated erythroblasts and enhanced HbF synthesis up to 85% F cells and 55% γ-globin content at terminal maturation (ie, in more than 80%-90% mature erythroblasts). Equivalent results were obtained in unicellular erythroid cultures of sibling BFU-Es treated with KL alone or combined with graded amounts of Dex. These results indicate that the stimulatory effect of KL + Dex is related to the modulation of γ-globin expression rather than to recruitment of BFU-Es with elevated HbF synthetic potential. At the molecular level, Id2 expression is totally suppressed in control erythroid culture but is sustained in KL + Dex culture. Hypothetically, Id2 may mediate the expansion of early erythroid cells, which correlates with HbF reactivation. These studies indicate that GCs play an important role in HbF reactivation. Because Dex acts at dosages used in immunologic disease therapy, KL + Dex administration may be considered to develop preclinical models for β-hemoglobinopathy treatment

Molecular Identification of Atlantic Bluefin Tuna (Thunnus thynnus, Scombridae) Larvae and Development of a DNA Character-Based Identification Key for Mediterranean Scombrids

The Atlantic bluefin tuna, Thunnus thynnus, is a commercially important species that has been severely over-exploited in the recent past. Although the eastern Atlantic and Mediterranean stock is now showing signs of recovery, its current status remains very uncertain and as a consequence their recovery is dependent upon severe management informed by rigorous scientific research. Monitoring of early life history stages can inform decision makers about the health of the species based upon recruitment and survival rates. Misidentification of fish larvae and eggs can lead to inaccurate estimates of stock biomass and productivity which can trigger demands for increased quotas and unsound management conclusions. Herein we used a molecular approach employing mitochondrial and nuclear genes (CO1 and ITS1, respectively) to identify larvae (n = 188) collected from three spawning areas in the Mediterranean Sea by different institutions working with a regional fisheries management organization. Several techniques were used to analyze the genetic sequences (sequence alignments using search algorithms, neighbour joining trees, and a genetic character-based identification key) and an extensive comparison of the results is presented. During this process various inaccuracies in related publications and online databases were uncovered. Our results reveal important differences in the accuracy of the taxonomic identifications carried out by different ichthyoplanktologists following morphology- based methods. While less than half of larvae provided were bluefin tuna, other dominant taxa were bullet tuna (Auxis rochei), albacore (Thunnus alalunga) and little tunny (Euthynnus alletteratus). We advocate an expansion of expertise for a new generation of morphology-based taxonomists, increased dialogue between morphology-based and molecular taxonomists and increased scrutiny of public sequence databases.Versión del editor4,411

Regulation of transferrin receptor 2 in human cancer cell lines.

In a recent study we have explored TfR2 expression in a panel of cancer cell lines and we observed that about 40% of these cell lines clearly express TfR2. Taking advantage of this observation and considering the frequent overexpression of c-Myc in cancer cells we have explored the existence of a possible relationship between c-Myc and TfR2 in these cell lines. Our results provided evidence that TfR2(+) cell lines express low c-Myc levels and low TfR1 levels, while TfR2(-) cell lines express high c-Myc and TfR1 levels. Using the erythroleukemic K562 TfR2(+) cells as a model, we observed that agents that enhance c-Myc expression, such as iron, determine a decrease of TfR2 expression, while molecules that induce a decreased c-Myc expression, such as the iron chelator desferoxamine or the kinase inhibitor ST 1571, induce an enhanced TfR2 expression. On the other hand, we have evaluated a possible effect of hypoxia and nitric oxide on TfR2 expression in erythroleukemia K526 and hepatoma HepG2 cells, providing evidence that: (i) agents inducing cellular hypoxia, such as CoCl(2), elicited a marked upmodulation of TfR1, but a downmodulation of TfR2 expression; (ii) NO(+) donors, such as sodium nitroprusside (SNP), induced a moderate decrease of TfR1, associated with a marked decline of TfR2 expression; (iii) NO donors, such as S-Nitroso-N-Acetylpenicillamine (SNAP), induced a clear increase of TfR1, associated with a moderate upmodulation of TfR2 expression. The ensemble of these observations suggests that in cancer cell lines TfR2 expression can be modulated through stimuli similar to those known to act on TfR1 and these findings may have important implications for our understanding of the role of TfR2 in the regulation of iron homeostasis

Erythropoietin, hemoglobin and endothelial progenitor cell levels in patients with acute myocardial infarction

We investigated whether changes in plasmatic erythropoietin (Epo) levels in patients with acute myocardial infarction (AMI) reflect changes in hemoglobin (Hb) levels. We studied plasma Epo levels and their relation with Hb and endothelial progenitors in patients with AMI and in patients with unstable angina (UAP). The number of endothelial progenitors was higher in patients with LVEF>40 than in those with LVEF<40

Proteasome inhibitors sensitize ovarian cancer cells to TRAIL induced apoptosis

In the present study we have explored the sensitivity of ovarian cancer cells to TRAIL and proteasome inhibitors. Particularly, we have explored the capacity of proteasome inhibitors to bypass TRAIL resistance of ovarian cancer cells. For these studies we have used the A2780 ovarian cancer cell line and its chemoresistant derivatives A2780/DDP and A2780/ADR, providing evidence that: (i) the three cell lines are either scarcely sensitive (A2780 and A2780/ADR) or moderately sensitive (A2780/DDP) to the cytotoxic effects of TRAIL; (ii) the elevated c-FLIP expression observed in ovarian cancer cells is a major determinant of TRAIL resistance of these cells; (iii) proteasome inhibitors (PS-341 or MG132) are able to exert a significant pro-apoptotic effect and to greatly enhance the sensitivity of both chemosensitive and chemoresistant A2780 cells to TRAIL; (iv) proteasome inhibitors damage mitochondria through stabilization of BH3-only proteins, Bax and caspase activation and significantly enhance TRAIL-R2 expression; (v) TRAIL-R2, but not TRAIL-R1, mediates the apoptotic effects of TRAIL on ovarian cancer cells. Importantly, studies on primary ovarian cancer cells have shown that these cells are completely resistant to TRAIL and proteasome inhibitors markedly enhance the sensitivity of these cells to TRAIL. Given the high susceptibility of ovarian cancer cells to proteasome inhibitors, our results further support the experimental use of these compounds in the treatment of ovarian cancer

A small molecule Smac mimic potentiates TRAIL-mediated cell death of ovarian cancer cells

Objectives.: Ovarian cancer remains a leading cause of death in women and development of new therapies is essential. Second mitochondria derived activator of caspase (Smac) has been described to sensitize for apoptosis. We have explored the proapoptotic activity of a small molecule mimic of Smac/DIABLO on ovarian cancer cell lines (A2780 cells and its chemoresistant derivatives A2780/ADR and A2780/DDP), cancer cell lines and in primary ovarian cancer cells. Methods.: The effects of a small molecule mimic of Smac/DIABLO on ovarian cancer cell lines and primary ovarian cancer cells were determined by cell proliferation, apoptosis and biochemical assays. Results.: This compound added alone elicited only a weak proapoptotic effect; however, it strongly synergizes with tumor necrosis factor-related apoptosis inducing ligand (TRAIL) or agonistic TRAILR2 antibody (Lexatumumab) in inducing apoptosis of ovarian cancer cells. Conclusions.: These observations suggest that small molecule mimic of Smac/DIABLO could be useful for the development of experimental strategies aiming to treat ovarian cancer. Interestingly, in addition to its well known proapoptotic effects, Smac/DIABLO elicited a significant increase of pro-caspase-3 levels. © 2007 Elsevier Inc. All rights reserved

High sensitivity of ovarian cancer cells to the synthetic triterpenoid CDDO-Imidazolide

In the present study we have explored the sensitivity of ovarian cancer cells to the synthetic triterpenoid CDDO-Imidazolide (CDDO-Im). For these studies we have used the A2780 ovarian cancer cell line and its chemoresistant derivatives A2780/ADR and A2780/CISP, OVCAR3, SKOV3 and HEY cancer cell lines and primary ovarian cancer cells, providing evidence that: (i) the majority of these cell lines are highly sensitive to the pro-apoptotic effects induced by CDDO-Im: (ii) TRAIL, added alone exerted only a weak proapoptotic, but clearly potentiated the cytotoxic effect elicited by CDDO-Im; (iii) the apoptotic effect induced by CDDO-Im involves GSH depletion, c-FLIP downmodulation and caspase-8 activation: (iv) CDDO-Im inhibits STAT3 activation and CDDO-Im sensitivity is inversely related to the level of constitutive STAT3 activation. Importantly, studies on primary ovarian cancer cells have shown that these cells are sensitive to the pro-apoptotic effects of CDDO-Im. These observations support the experimental use of synthetic triterpenoids in the treatment of ovarian cancer. (C) 2009 Elsevier Ireland Ltd. All rights reserved