José Segovia

Resistance to chemotherapy via Stat3-dependent overexpression of Bcl-2 in metastatic breast cancer cells

Disruption of apoptosis may allow metastatic cell survival and confer resistance to chemotherapeutic drugs. We have analysed the molecular pathways that activate these survival genes in specific sites of metastasis. Estrogen receptor-negative breast cancer cell line MDA-MB435 and two metastatic sublines derived from lung (435L) and brain (435B) were analysed for the expression of members of the Bcl-2 family of apoptosis regulators. The levels of Bcl-2 were higher in the metastatic sublines than in parental cells, which correlated with the activation of Stat3, but not with the expression and/or activation of known bcl-2 transcription factors (CREB and WT1). In the brain subline, both expression of Bcl-2 and Stat3 activation were induced by epidermal growth factor and abrogated after treatment with kinase inhibitors specific for epidermal growth factor receptor or Jak2. Furthermore, transfection of 435B with a dominant-negative Stat3 markedly reduced the expression of Bcl-2 protein, whereas transient expression of a constitutively active Stat3 increased Bcl-2 in parental 435 cells. In addition, blockade of Stat3 activation by treatment with epidermal growth factor receptor and Jak2 kinase inhibitors or transfection with a dominant negative Stat3, sensitizes 435B cells to chemotherapy-induced apoptosis. Our data suggest that an increased activation of the Stat3–Bcl-2 pathway in estrogen receptor-negative metastatic breast cancer cell lines confer a survival advantage to these cells and contribute to their chemoresistance.

Hematopoietic mobilization in mice increases the presence of bone marrow-derived hepatocytes via in vivo cell fusion.

The mechanisms for in vivo production of bone marrow–derived hepatocytes (BMDHs) remain largely unclear. We investigated whether granulocyte colony–stimulating factor (G‐CSF)–mediated mobilization of hematopoietic cells increases the phenomenon. Recurrent liver injury in mice expressing green fluorescent protein (EGFP) in all hematopoietic‐derived cells was produced by 3 months of carbon tetrachloride (CCL4) injections. Histologically, there were necrotic foci with histiocyte‐rich infiltrates, but little oval cell proliferation. Subsequently, some animals were mobilized with G‐CSF for 1, 2, or 3 weeks. Animals were sacrificed 1 month after growth factor treatment. BMDH percentages were lower than previously reported, though G‐CSF mobilization significantly augmented BMDH production in injured livers. BMDHs originating from in vivo fusion were evaluated by transplanting female EGFP+ cells into male mice. Binucleated, EGFP+ hepatocytes with one Y chromosome, indicating fusion, were identified. In conclusion, (1) mobilization of hematopoietic cells increases BMDH production and (2) as with the FAH‐null model, the first model demonstrating hematopoietic/hepatocyte fusion, recurring CCl4‐induced injury has macrophage‐rich infiltrates, a blunted oval cell response, and a predominantly in vivo fusion process for circulating cell engraftment into the liver. These findings open the possibility of using hematopoietic growth factors to treat nonhematopoietic degenerative diseases. (HEPATOLOGY 2006;43:108–116.)

Curcumin prevents and reverses cirrhosis induced by bile duct obstruction or CCl4 in rats: role of TGF-β modulation and oxidative stress

Curcumin is a phytophenolic compound, which is highly efficacious for treating several inflammatory diseases. The aim of this study was to evaluate the efficacy of curcumin in preventing or reversing liver cirrhosis. A 4‐week bile duct ligation (BDL) rat model was used to test the ability of curcumin (100 mg/kg, p.o., daily) to prevent cirrhosis. To reverse cirrhosis, CCl4 was administered chronically for 3 months, and then it was withdrawn and curcumin administered for 2 months. Alanine aminotransferase, γ‐glutamyl transpeptidase, liver histopathology, bilirubin, glycogen, reduced and oxidized glutathione, and TGF‐β (mRNA and protein) levels were assessed. Curcumin preserved normal values of markers of liver damage in BDL rats. Fibrosis, assessed by measuring hydroxyproline levels and histopathology, increased nearly fivefold after BDL and this effect was partially but significantly prevented by curcumin. BDL increased transforming growth factor‐beta (TGF‐β) levels (mRNA and proteins), while curcumin partially suppressed this mediator of fibrosis. Curcumin also partially reversed the fibrosis induced by CCl4. Curcumin was effective in preventing and reversing cirrhosis, probably by its ability of reducing TGF‐β expression. These data suggest that curcumin might be an effective antifibrotic and fibrolitic drug in the treatment of chronic hepatic diseases.

Interacting Resident Epicardium-Derived Fibroblasts and Recruited Bone Marrow Cells Form Myocardial Infarction Scar

BACKGROUND Although efforts continue to find new therapies to regenerate infarcted heart tissue, knowledge of the cellular and molecular mechanisms involved remains poor. OBJECTIVES This study sought to identify the origin of cardiac fibroblasts (CFs) in the infarcted heart to better understand the pathophysiology of ventricular remodeling following myocardial infarction (MI). METHODS Permanent genetic tracing of epicardium-derived cell (EPDC) and bone marrow-derived blood cell (BMC) lineages was established using Cre/LoxP technology. In vivo gene and protein expression studies, as well as in vitro cell culture assays, were developed to characterize EPDC and BMC interaction and properties. RESULTS EPDCs, which colonize the cardiac interstitium during embryogenesis, massively differentiate into CFs after MI. This response is disease-specific, because angiotensin II-induced pressure overload does not trigger significant EPDC fibroblastic differentiation. The expansion of epicardial-derived CFs follows BMC infiltration into the infarct site; the number of EPDCs equals that of BMCs 1 week post-infarction. BMC-EPDC interaction leads to cell polarization, packing, massive collagen deposition, and scar formation. Moreover, epicardium-derived CFs display stromal properties with respect to BMCs, contributing to the sustained recruitment of circulating cells to the damaged zone and the cardiac persistence of hematopoietic progenitors/stem cells after MI. CONCLUSIONS EPDCs, but not BMCs, are the main origin of CFs in the ischemic heart. Adult resident EPDC contribution to the CF compartment is time- and disease-dependent. Our findings are relevant to the understanding of post-MI ventricular remodeling and may contribute to the development of new therapies to treat this disease.

Targeted gene therapy and cell reprogramming in Fanconi anemia

Gene targeting is progressively becoming a realistic therapeutic alternative in clinics. It is unknown, however, whether this technology will be suitable for the treatment of DNA repair deficiency syndromes such as Fanconi anemia (FA), with defects in homology‐directed DNA repair. In this study, we used zinc finger nucleases and integrase‐defective lentiviral vectors to demonstrate for the first time that FANCA can be efficiently and specifically targeted into the AAVS1 safe harbor locus in fibroblasts from FA‐A patients. Strikingly, up to 40% of FA fibroblasts showed gene targeting 42 days after gene editing. Given the low number of hematopoietic precursors in the bone marrow of FA patients, gene‐edited FA fibroblasts were then reprogrammed and re‐differentiated toward the hematopoietic lineage. Analyses of gene‐edited FA‐iPSCs confirmed the specific integration of FANCA in the AAVS1 locus in all tested clones. Moreover, the hematopoietic differentiation of these iPSCs efficiently generated disease‐free hematopoietic progenitors. Taken together, our results demonstrate for the first time the feasibility of correcting the phenotype of a DNA repair deficiency syndrome using gene‐targeting and cell reprogramming strategies.

A comprehensive strategy for the subtyping of patients with Fanconi anaemia: conclusions from the Spanish Fanconi Anemia Research Network

Background: Fanconi anaemia is a heterogeneous genetic disease, where 12 complementation groups have been already described. Identifying the complementation group in patients with Fanconi anaemia constitutes a direct procedure to confirm the diagnosis of the disease and is required for the recruitment of these patients in gene therapy trials. Objective: To determine the subtype of Fanconi anaemia patients in Spain, a Mediterranean country with a relatively high population (23%) of Fanconi anaemia patients belonging to the gypsy race. Methods: Most patients could be subtyped by retroviral complementation approaches in peripheral blood T cells, although some mosaic patients were subtyped in cultured skin fibroblasts. Other approaches, mainly based on western blot analysis and generation of nuclear RAD51 and FANCJ foci, were required for the subtyping of a minor number of patients. Results and conclusions: From a total of 125 patients included in the Registry of Fanconi Anaemia, samples from 102 patients were available for subtyping analyses. In 89 cases the subtype could be determined and in 8 cases exclusions of common complementation groups were made. Compared with other international studies, a skewed distribution of complementation groups was observed in Spain, where 80% of the families belonged to the Fanconi anaemia group A (FA-A) complementation group. The high proportion of gypsy patients, all of them FA-A, and the absence of patients with FA-C account for this characteristic distribution of complementation groups.

Lentiviral-mediated Genetic Correction of Hematopoietic and Mesenchymal Progenitor Cells From Fanconi Anemia Patients

Previous clinical trials based on the genetic correction of purified CD34(+) cells with gamma-retroviral vectors have demonstrated clinical efficacy in different monogenic diseases, including X-linked severe combined immunodeficiency, adenosine deaminase deficient severe combined immunodeficiency and chronic granulomatous disease. Similar protocols, however, failed to engraft Fanconi anemia (FA) patients with genetically corrected cells. In this study, we first aimed to correlate the hematological status of 27 FA patients with CD34(+) cell values determined in their bone marrow (BM). Strikingly, no correlation between these parameters was observed, although good correlations were obtained when numbers of colony-forming cells (CFCs) were considered. Based on these results, and because purified FA CD34(+) cells might have suboptimal repopulating properties, we investigated the possibility of genetically correcting unselected BM samples from FA patients. Our data show that the lentiviral transduction of unselected FA BM cells mediates an efficient phenotypic correction of hematopoietic progenitor cells and also of CD34(-) mesenchymal stromal cells (MSCs), with a reported role in hematopoietic engraftment. Our results suggest that gene therapy protocols appropriate for the treatment of different monogenic diseases may not be adequate for stem cell diseases like FA. We propose a new approach for the gene therapy of FA based on the rapid transduction of unselected hematopoietic grafts with lentiviral vectors (LVs).Previous clinical trials based on the genetic correction of purified CD34+ cells with γ-retroviral vectors have demonstrated clinical efficacy in different monogenic diseases, including X-linked severe combined immunodeficiency, adenosine deaminase deficient severe combined immunodeficiency and chronic granulomatous disease. Similar protocols, however, failed to engraft Fanconi anemia (FA) patients with genetically corrected cells. In this study, we first aimed to correlate the hematological status of 27 FA patients with CD34+ cell values determined in their bone marrow (BM). Strikingly, no correlation between these parameters was observed, although good correlations were obtained when numbers of colony-forming cells (CFCs) were considered. Based on these results, and because purified FA CD34+ cells might have suboptimal repopulating properties, we investigated the possibility of genetically correcting unselected BM samples from FA patients. Our data show that the lentiviral transduction of unselected FA BM cells mediates an efficient phenotypic correction of hematopoietic progenitor cells and also of CD34- mesenchymal stromal cells (MSCs), with a reported role in hematopoietic engraftment. Our results suggest that gene therapy protocols appropriate for the treatment of different monogenic diseases may not be adequate for stem cell diseases like FA. We propose a new approach for the gene therapy of FA based on the rapid transduction of unselected hematopoietic grafts with lentiviral vectors (LVs).

Preserved long-term repopulation and differentiation properties of hematopoietic grafts subjected to ex vivo expansion with stem cell factor and interleukin 11.

BACKGROUND The ex vivo expansion of hematopoietic grafts has been proposed as an efficient procedure for improving the hematological recovery of recipients. The fate of the long-term repopulating cells during the ex vivo manipulation of the graft is, however, a critical issue in ex vivo expansion protocols and ultimately will define the applicability of this new technology in hematopoietic transplants. METHODS The repopulating ability of mouse hematopoietic samples was determined by means of bone marrow (BM*) competition assays, using congenic strains that express the pan-leukocyte Ly-5.1 and Ly-5.2 antigens. The generation of potential changes in the repopulating properties of human hematopoietic samples subjected to ex vivo expansion was determined by comparing the engraftment of fresh and ex vivo-manipulated CD34+ cord blood cells in irradiated nonobese diabetic/severe-combined immunodeficient (NOD/SCID) mice. RESULTS Under our optimized conditions of mouse BM incubation (stem cell factor plus interleukin-11, either with or without macrophage inflammatory protein-1alpha or Flt3 ligand), both the short-term and the mid-term repopulating ability of the ex vivo-expanded samples were significantly improved when compared with fresh samples. In the long-term, no changes in the repopulation and differentiation properties of the graft were observed as a result of the ex vivo expansion process. As deduced from the analysis of NOD/SCID mice transplanted with fresh and ex vivo expanded human CD34+ cord blood cells, the in vitro stimulation mediated by SCF/IL-11/FLT3L was capable of preserving the ability of the grafts to repopulate the lympho-hematopoiesis of recipients for at least 3 months. CONCLUSION These results indicate that under our optimized conditions of ex vivo expansion, the amplification of the hematopoietic progenitors responsible for the short- and mid-term repopulating properties of the graft can take place without compromising the long-term lympho-hematopoietic repopulating properties.

Ex vivo expansion of umbilical cord blood (UCB) CD34+ cells alters the expression and function of α4β1 and α5β1 integrins

We have investigated the influence of ex vivo expansion of human CD34+ cord blood cells on the expression and function of adhesion molecules involved in the homing and engraftment of haematopoietic progenitors. Ex vivo expansion of umbilical cord blood CD34+ cells for 6 d in the presence of interleukin 3 (IL‐3), IL‐6 and stem cell factor (SCF) or IL‐11, SCF and Flt‐3L resulted in increased expression of α4, α5, β1, αΜM and β2 integrins. However, a significant decrease in the adhesion of progenitor cells to fibronectin was observed after the ex vivo culture (adhesion of granulocyte‐macrophage colony‐forming units (CFU‐GM) was 22 ± 4% in fresh cells versus 5 ± 2% and 2 ± 2% in each combination of cytokines). Incubation with the β1 integrin‐activating antibody TS2/16 restored adhesion to fibronectin. Transplantation of ex vivo expanded umbilical cord blood CD34+ cells was associated with an early delayed engraftment in non‐obese diabetic/severe combined immunodeficient (NOD/SCID) mice. Incubation of cells with the monoclonal antibody TS2/16 before transplantation almost completely abrogated NOD/SCID repopulating ability of both fresh and expanded CD34+ cells. The seeding efficiency of fresh and expanded CD34+ cells was similar, but markedly reduced after incubation with the TS2/16 monoclonal antibody. Our results show that functional activation of β1 integrins could overcome the decreased very late antigen (VLA)‐4‐ and VLA‐5‐mediated adhesion observed after ex vivo expansion of haematopoietic progenitors. However, in vivo, these effects induced an almost complete abrogation of the homing and repopulating ability of CD34+ UCB cells.

Antifibrotic and fibrolytic properties of celecoxib in liver damage induced by carbon tetrachloride in the rat

Background: Transforming growth factor‐β (TGF‐β) plays a pivotal role in liver fibrosis, because it activates hepatic stellate cells, stimulating extracellular matrix deposition. Cyclooxygenase‐2 (COX‐2) has been associated with TGF‐β because its inhibition decreases TGF‐β expression and collagen production in some cultured cell types.