Giuseppina Bonanno

Quercetin potentiates the effect of adriamycin in a multidrug-resistant MCF-7 human breast-cancer cell line: P-glycoprotein as a possible target

This study demonstrates that the flavonoid quercetin (Q), a plant-derived compound with low toxicity in vivo, greatly potentiates the growth-inhibitory activity of Adriamycin (ADR) on MCF-7 ADR-resistant human breast cancer cells. The effect of Q was dose-dependent at concentrations ranging between 1 and 10 μM. Since ADR resistance in these cells is associated with the expression of high levels of P-glycoprotein (Pgp), we evaluated the effect of Q and related flavonoids of Pgp activity in cytofluorographic efflux experiments with the fluorescent dye rhodamine 123 (Rh 123). Our results indicate that Q and 3-OMe Q (3′,4′,7-trimethoxyquercetin) but not the 3-rhamnosylglucoside of Q (rutin) inhibit the Pgp pump-efflux activity in a dose-related manner. Moreover, 10 μM Q reduces the expression of the immunoreactive Pgp in MCF-7 ADR-resistant cells as evaluated by cytofluorimetric assay. In conclusion, these findings provide a further biological basis for the potential therapeutic application of Q as an anticancer drug either alone or in combination with ADR in multidrug-resistant breast tumor cells.

Myoendothelial Differentiation of Human Umbilical Cord Blood–Derived Stem Cells in Ischemic Limb Tissues

Abstract— Human umbilical cord blood (UCB) contains high numbers of endothelial progenitors cells (EPCs) characterized by coexpression of CD34 and CD133 markers. Prior studies have shown that CD34+/CD133+ EPCs from the cord or peripheral blood (PB) can give rise to endothelial cells and induce angiogenesis in ischemic tissues. In the present study, it is shown that freshly isolated human cord blood CD34+ cells injected into ischemic adductor muscles gave rise to endothelial and, unexpectedly, to skeletal muscle cells in mice. In fact, the treated limbs exhibited enhanced arteriole length density and regenerating muscle fiber density. Under similar experimental conditions, CD34− cells did not enhance the formation of new arterioles and regenerating muscle fibers. In nonischemic limbs CD34+ cells increased arteriole length density but did not promote formation of new muscle fibers. Endothelial and myogenic differentiation ability was maintained in CD34+ cells after ex vivo expansion. Myogenic conversion of human cord blood CD34+ cells was also observed in vitro by coculture onto mouse myoblasts. These results show that human cord blood CD34+ cells differentiate into endothelial and skeletal muscle cells, thus providing an indication of human EPCs plasticity. The full text of this article is available online at http://www.circresaha.org.

Transplantation of low dose CD34+Kdr+ cells promotes vascular and muscular regeneration in ischemic limbs

Hematopoietic progenitor cell transplantation can contribute to revascularization of ischemic tissues. Yet, the optimal cell population to be transplanted has yet to be determined. We have compared the therapeutic potential of two subsets of human cord blood CD34+ progenitors, either expressing the VEGF‐A receptor 2 (KDR) or not. In serum‐free starvation culture, CD34+KDR+ cells reportedly showed greater resistance to apoptosis and ability to release VEGF‐A, as compared with CD34+KDR− cells. When injected into the hind muscles in immunodeficient SCIDbg mice subjected to unilateral ischemia, a low number (103) of CD34+KDR+ cells improved limb salvage and hemodynamic recovery better than a larger dosage (104) of CD34+KDR− cells. The neovascularization induced by KDR+ cells was significantly superior to that promoted by KDR− cells. Similarly, endothelial cell apoptosis and interstitial fibrosis were significantly attenuated by KDR+ cells, which differentiated into mature human endothelial cells and also apparently skeletal muscle cells. This study demonstrates that a low number of CD34+KDR+ cells favors reparative neovascularization and possibly myogenesis in limb ischemia, suggesting the potential use of this cell population in regenerative medicine.

Cells with Characteristics of Cancer Stem/Progenitor Cells Express the CD133 Antigen in Human Endometrial Tumors

Purpose: Cancer stem cells represent an attractive therapeutic target for tumor eradication. The present study aimed to determine whether CD133 expression may identify cells with characteristics of cancer stem/progenitor cells in human endometrial tumors. Experimental Design: We analyzed 113 tumor samples for CD133/1 expression by flow cytometry, immunohistochemistry, and semiquantitative reverse transcription–PCR. CD133+ cells were isolated and used to assess phenotypic characteristics, self-renewal capacity, ability to maintain CD133 expression and form sphere-like structures in long-term cultures, sensitivity to chemotherapeutic agents, gene expression profile, and ability to initiate tumors in NOD/SCID mice. Results: Primary tumor samples exhibited a variable degree of immunoreactivity for CD133/1, ranging from 1.3% to 62.6%, but stained negatively for other endothelial and stem cell–associated markers. Isolated CD133+ cells expanded up to 4.6-fold in serum-replenished cultures and coexpressed the GalNAcα1-O-Ser/Thr MUC-1 glycoform, a well-characterized tumor-associated antigen. Dissociated bulk tumors formed sphere-like structures; cells grown as tumor spheres maintained CD133 expression and could be propagated for up to 12 weeks. CD133+ cells purified from endometrioid adenocarcinomas were resistant to cisplatin-induced and paclitaxel-induced cytotoxicity and expressed a peculiar gene signature consisting of high levels of matrix metalloproteases, interleukin-8, CD44, and CXCR4. When serially transplanted into NOD/SCID mice, CD133+ cells were capable of initiating tumor formation and recapitulating the phenotype of the original tumor. Conclusions: CD133 is expressed by human endometrial cancers and might represent a valuable tool to identify cells with cancer stem cell characteristics.

Granulocyte colony‐stimulating factor promotes the generation of regulatory DC through induction of IL‐10 and IFN‐α

We have recently demonstrated that G‐CSF promotes the generation of human T regulatory (TREG) type 1 cells. In this study, we investigated whether the immunomodulatory effects of G‐CSF might be mediated by DC. CD14+ monocytes were cultured with serum collected after clinical administration of G‐CSF (post‐G), which contained high amounts of IL‐10 and IFN‐α. Similar to incompletely matured DC, monocytes nurtured with post‐G serum acquired a DC‐like morphology, expressed high levels of costimulatory molecules and HLA‐DR, and exhibited diminished IL‐12p70 release and poor allostimulatory capacity. Importantly, post‐G DC‐like cells were insensitive to maturation stimuli. As shown by neutralization studies, IFN‐α and, even more pronounced, IL‐10 contained in post‐G serum inhibited IL‐12p70 release by post‐G DC‐like cells. Furthermore, phenotypic and functional features of post‐G DC‐like cells were replicated by culturing post‐G monocytes with exogenous IL‐10 and IFN‐α. Post‐G DC‐like cells promoted Ag‐specific hyporesponsiveness in naive allogeneic CD4+ T cells and orchestrated a TREG response that was dependent on secreted TGFβ1 and IL‐10. Finally, neutralization of IL‐10 and IFN‐α contained in post‐G serum translated into abrogation of the regulatory features of post‐G DC‐like cells. This novel mechanism of immune regulation effected by G‐CSF might be therapeutically exploited for tolerance induction in autoimmune disorders.

Quercetin inhibits the growth of a multidrug-resistant estrogen-receptor-negative MCF-7 human breast-cancer cell line expressing type II estrogen-binding sites

SummaryIt has been demonstrated that the flavonoid quercetin (3,3′,4′,5,7-pentahydroxyflavone; Q) inhibits the growth of several cancer cell lines. There is evidence suggesting that the antiproliferative activity of this substance is mediated by the so-called type II estrogen-binding, site (type II EBS). We looked for the presence of type II EBS and the effect of Q on the proliferation of an Adriamycinresistant estrogen-receptor-negative human breast-cancer cell line (MCF-7 ADRr). By whole-cell assay using estradiol labelled with 6,7-tritium ([3H]-E2) as a tracer, we demonstrated that MCF-7 ADRr cells contain type II EBSs. Competition analysis revealed that diethylstilbestrol (DES) and Q competed with similar potency for [3H]-Es binding to type II EBSs. The antiestrogen tamoxifen (TAM) competed for type II EBSs, albeit to a lesser extent than either DES or Q. Growth experiments demonstrated that Q and DES exerted a dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nM and 10 μm, whereas TAM was less effective. Q could also inhibit colony formation in a clonogenic assay. Our results indicate that multidrug-resistant estrogen-receptor-negative MCF-7 cells express, type II EBSs and are sensitive to the inhibitory effect of Q. This substance could be the parent compound of a novel class of anticancer agents.

Inhibitory effect of quercetin on OVCA 433 cells and presence of type II oestrogen binding sites in primary ovarian tumours and cultured cells

We investigated the effect of the flavonoid quercetin (Q) on the proliferation of the ovarian cancer cell line OVCA 433. Growth experiments demonstrated that Q exerted a reversible dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nM and 10 microM. Two other flavonoids tested, rutin and hesperidin, were ineffective in inhibiting cell growth. Cell cycle analysis showed that the growth inhibitory effect of Q was due to a blocking effect in the GO/G1 phase. Using a whole cell assay with (6.7-3H) oestradiol (3H-E2) as tracer we demonstrated that OVCA 433 cells contain type II oestrogen binding sites (type II EBS). Competition analysis showed that Q competed for 3H-E2 binding to type II EBS while both rutin and hesperidin did not. Appreciable amounts of type II EBS were also detected in seven primary ovarian tumours. Our results suggest that Q may regulate ovarian cancer cell growth through a mechanism involving a binding interaction with type II EBS. This mechanism could also be active in vivo since primary ovarian tumours contain type II EBS.

Targeting CD133 antigen in cancer

Background: Much attention has been focused on CD133 as a marker of cancer cells with stem-cell-like ability. In the cancer stem cells (CSCs) model, only a small proportion of tumour cells are able to self-renew extensively, while the bulk of cells proceed to differentiate into committed heterogeneous clones. On the basis of the involvement of CSCs in tumourigenesis and treatment resistance, it is conceivable that only eradication of CSCs can lead to a cancer cure. Objective: To highlight the most recent evidence about the role of CD133 as a marker of CSCs in human tumours, and the therapeutic perspectives associated with its specific targeting. Methods: A literature search through Medline to locate published full articles using the following key words for selection: ‘CD133 and cancer targeting’, ‘CD133 and chemo resistance’, and ‘CD133 and molecular pathways’. Only studies in English are considered. Results/Conclusions: The role of CD133 as a marker of CSCs has been documented in several human neoplasms; its expression seems to predict unfavourable prognosis. Novel therapeutic strategies aimed at targeting molecular pathways critical for CD133+ CSCs survival are being examined.

CD105 (Endoglin) Expression on Hematopoietic Stem/Progenitor Cells

Endoglin (CD105) is a component of the transforming growth factor-β (TGF-β) receptor (TGF-βR) complex. Together with betaglycan, CD105 is considered as a TGF-βR accessory molecule (also called TGF-βRIII), but its functions in the receptor-ligand interactions are still poorly understood. A small subset of human CD34+ hematopoietic stem/progenitor cells that has phenotypic and functional features suggestive of very primitive hematopoietic cells expresses the CD105 antigen. CD34+/CD105+ cells recirculate in the peripheral blood of mobilized subjects and can be purified by immunomagnetic isolation strategies. The hematopoietic potential of these CD34+/CD105+ cells appears to be sustained by a combination of hematopoietic and non-hematopoietic cytokines, which comprises Flt3 ligand, erythropoietin, interleukin-15 and vascular endothelial growth factor. Endogenous TGF-β1 is a crucial factor for the maintenance of CD34+/CD105+ immaturity acting through positive modulation of both CD105 and CD34 molecules in the absence of relevant effects on the cell cycle profile. CD105 is absent on very primitive CD34-/lineage-/CD45+ (CD34-Lin-) human hematopoietic cells isolated from cord blood. However, in vitro exposure of CD34-Lin-cells to exogenous TGF-β1 causes the appearance of a discrete population of CD34+/CD105+ cells. Collectively, available data on CD105 expression and function in primitive hematopoiesis indicate that this molecule could cooperate with the dissociation of TGF-β1 cell cycle effects from its other effects on cell survival and differentiation.

Inhibitory effect of quercetin on primary ovarian and endometrial cancers and synergistic activity with cis-diamminedichloroplatinum(II)

Abstract It has been demonstrated that the flavonoid quercetin (3,3′,4′,5,7-pentahydroxyflavone) inhibits the growth of several cancer cell lines and that the antiproliferative activity of this substance is mediated by so-called type II estrogen binding sites. Moreover it has been observed that quercetin enhances the antiproliferative activity of cis -diamminedichloroplatinum(II) (CDDP) and busulfan both in vitro and in vivo . We tested the effect of quercetin and its combination of CDDP on clonogenic cells of nine primary gynecological tumors (four ovarian and five endometrial tumors). Quercetin produced a dose-dependent inhibition of colony formation in a range of concentrations between 0.01 and 10 μM . The bromodeoxyuridine uptake into neoplastic specimens was evaluated immunocytochemically: quercetin at 10 μM concentration produced a clear reduction in the number of bromodeoxyuridine-labeled cells. The simultaneous treatment with quercetin and CDDP (in a range of concentration between 0.01 and 10 μM and 0.01 and 0.5 μg/ml, respectively) resulted in a marked synergistic antiproliferative activity in all cases, with a CDDP potentiation ranging from 1.5- to 30-fold. The combination of quercetin with two other chemotherapeutic agents, Adriamycin and etoposide (VP-16), did not yield any enhancement of the antiproliferative activity. Two other flavonoids tested, rutin and hesperidin, were ineffective on colony formation both alone and in combination with CDDP.