Mariana A Callero

University of Buenos Aires, Buenos Aires, Buenos Aires F.D., Argentina

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Publications (7)17.21 Total impact

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    ABSTRACT: 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F203, NSC 703786) lysylamide belongs to a novel mechanistic class of antitumor agents. It elicits activity against ovarian, breast, kidney and colorectal cancer models. In sensitive breast cancer cells, 5F203 activates aryl hydrocarbon receptor (AhR) signaling. Herein, we evaluate the role of AhR in 5F203 activity in two ovarian cancer cell lines: IGROV-1 (sensitive to 5F203), SKOV-3 (resistant to this agent). In addition, cancer cells have been isolated from ascites fluid of ovarian cancer patients; sensitivity to 5F203 and concurrent AhR signal transduction has been examined in ascites-isolated ovarian cancer patients' cells. 5F203 induced enhanced CYP1A1 expression, AhR translocation and ROS formation in IGROV-1 cells and ascites-isolated ovarian cancer cells that were sensitive to 5F203. In IGROV-1 cells 5F203-induced ROS formation was accompanied by JNK, ERK and P38MAPK phosphorylation, DNA damage and cell cycle arrest prior to apoptosis. In contrast, 5F203 failed to induce CYP1A1 expression, AhR translocation or oxidative stress in 5F203-resistant SKOV-3 cells, or in ovarian cancer ascites cells inherently resistant to this agent. We propose that AhR may represent a new molecular target in the treatment of ovarian tumors and 5F203 may exemplify a potential novel treatment. Furthermore, putative biomarkers of sensitivity to this agent have been identified. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.
    Journal of Cellular Biochemistry 05/2013; · 3.06 Impact Factor
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    ABSTRACT: Aminoflavone (AF; NSC 686288, AFP464, NSC710464) is a new anticancer drug that has recently entered phase II clinical trials. It has demonstrated antiproliferative effects in MCF-7 human breast cancer cells mediated by the aryl hydrocarbon receptor (AhR). AF also exhibits noteworthy evidence of antitumor activity in vitro and in vivo against neoplastic cells of renal origin. AF treatment of sensitive renal cells, in contrast to resistant cells, promotes the induction of CYP1A1, the covalent binding of AF-reactive intermediates and apoptosis. Based on this evidence, the aim of this study was to evaluate the role of AhR, the main transcriptional regulator of CYP1A1, in the antiproliferative effects of AF in human renal cancer cells. AF-cytoxicity in human renal cell lines and a renal cancer cell strain was assessed by MTS assay in the presence or absence of an Ahr inhibitor. Drug-induced AhR nuclear translocation was evaluated by western blotting of AhR in cytosolic and nuclear fractions and by measuring xenobiotic response element-driven luciferase activity. Apoptosis induced by the drug was evaluated by 4,6-diamidino-2-phenylindole and acridine orange/ethidium bromide staining and by measuring phosphorylated P53 (p-P53) and P21 levels, caspase 3 activation and poly(ADP-ribose) polymerase cleavage. AF inhibited cell growth in a dose-dependent manner in TK-10, Caki-1, SN12-C and A498 human renal cells but not in ACHN cells. The antiproliferative effect of AF was abrogated by pre-incubation of TK-10, Caki-1 and SN12-C cells with the AhR antagonist, α-naphthoflavone. AF treatment also induced apoptosis in TK-10, Caki-1 and SN12-C cells, which was not observed in ACHN cells. AF induced time-dependent AhR nuclear translocation and AhR transcriptional activity in sensitive renal cancer cell lines. A renal cell strain derived from a human papillary tumor also showed sensitivity to AF, as well as AhR pathway activation and drug-induced apoptosis. AhR translocation could be included as a marker of sensitivity to AF in sensitive renal tumor cells of different histological origin, in ongoing phase II clinical trials.
    International Journal of Oncology 04/2012; 41(1):125-34. · 2.66 Impact Factor
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    Mariana A Callero, Andrea I Loaiza-Pérez
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    ABSTRACT: Many estrogen-receptor- (ER-) expressing breast cancers become refractory to ER-based therapies. New antitumor drugs like aminoflavone (AF) and benzothiazoles (Bzs) have been developed and have exquisite antitumor activity in ER+MCF-7 and T47D cells and in a MCF-7 nude mouse model. ER(-) breast cancer cells like MDA-MB-231 are less susceptible. We previously found in MCF-7 cells that these drugs activate the aryl hydrocarbon receptor (AhR) via translocation to the nucleus, induction of AhR-specific DNA binding activity, and expression of CYP1A1, whose transcription is controlled by the AhR-ARNT transcription factor. CYP1A1 metabolizes AF and Bz to a species which directly or after further metabolism damages DNA. In contrast an AhR-deficient variant of MCF-7 or cells with predominantly nuclear AhR expression, such as MDA-MB 231, are resistant. Thus, these drugs, unlike other neoplastic agents, require AhR-mediated signaling to cause DNA damage. This is a new treatment strategy for breast cancers with intact AhR signaling.
    International journal of breast cancer. 01/2011; 2011:923250.
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    ABSTRACT: Erythropoietin (Epo) is crucial for promoting the survival, proliferation, and differentiation of mammalian erythroid progenitors. The central role played by tyrosine phosphorylation of erythropoietin receptor (EpoR) in Epo-cell activation has focused attention on protein tyrosine phosphatases (PTPs) as candidates implicated in the pathogenesis of the resistance to therapy with human recombinant Epo. Prototypic member of the PTP family is PTP1B, which has been implicated in the regulation of EpoR signaling pathways. In previous reports we have shown that PTP1B is reciprocally modulated by Epo in undifferentiated UT-7 cell line. However, no information is available with respect to the modulation of this phosphatase in non-Epo depending cells or at late stages of erythroid differentiation. In order to investigate these issues we induced UT-7 cells to differentiate and studied their PTP1B expression pattern. Simultaneous observations were performed in TF-1 cells which can be cultured either with GM-CSF, IL-3 or Epo. We found that Epo induced PTP1B cleaveage in TF-1 and differentiated UT-7 cells. This pattern of PTP1B modulation may be due to an increased TRPC3/TRPC6 expression ratio which could explain the larger and sustained calcium response to Epo and calpain activation in Epo treated TF-1 and differentiated UT-7 cells.
    Archives of Biochemistry and Biophysics 10/2010; 505(2):242-9. · 3.37 Impact Factor
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    ABSTRACT: The TNF-alpha (tumour necrosis factor) affects a wide range of biological activities, such as cell proliferation and apoptosis. Cell life or death responses to this cytokine might depend on cell conditions. This study focused on the modulation of factors that would affect the sensitivity of erythroid-differentiated cells to TNF-alpha. Hemin-differentiated K562 cells showed higher sensitivity to TNF-induced apoptosis than undifferentiated cells. At the same time, hemin-induced erythroid differentiation reduced c-FLIP (cellular FLICE-inhibitory protein) expression. However, this negative effect was prevented by prior treatment with Epo (erythropoietin), which allowed the cell line to maintain c-FLIP levels. On the other hand, erythroid-differentiated UT-7 cells - dependent on Epo for survival - showed resistance to TNF-alpha pro-apoptotic action. Only after the inhibition of PI3K (phosphatidylinositol-3 kinase)-mediated pathways, which was accompanied by negative c-FLIP modulation and increased erythroid differentiation, were UT-7 cells sensitive to TNF-alpha-triggered apoptosis. In summary, erythroid differentiation might deregulate the balance between growth promotion and death signals induced by TNF-alpha, depending on cell type and environmental conditions. The role of c-FLIP seemed to be critical in the protection of erythroid-differentiated cells from apoptosis or in the determination of their sensitivity to TNF-mediated programmed cell death. Epo, which for the first time was found to be involved in the prevention of c-FLIP down-regulation, proved to have an anti-apoptotic effect against the pro-inflammatory factor. The identification of signals related to cell life/death switching would have significant implications in the control of proliferative diseases and would contribute to the understanding of mechanisms underlying the anaemia associated with inflammatory processes.
    Cell Biology International 03/2010; 34(6):621-30. · 1.64 Impact Factor
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    ABSTRACT: Erythropoietin (Epo) is known to have a significant role in tissues outside the hematopoietic system. In this work, we investigated the function of Epo in cells of neuronal origin subjected to differentiation. Treatment of SH-SY5Y cells with all-trans-retinoic acid (atRA) generated differentiated neuron-like cells, observed by increased expression of neuronal markers and morphological changes. Exposure of undifferentiated cells to proapoptotic stimuli such as staurosporine, TNF-alpha, or hypoxia, significantly increased programmed cell death, which was prevented by previous treatment with Epo. In contrast, atRA-differentiated cultures showed cell resistance to apoptosis. No additional effect of Epo was detected in previously differentiated cells. The inhibition of the PI3K/Akt pathway by Ly294002 abrogated the protective effects induced by either Epo or atRA. The effect of atRA was mediated by an increased expression of Bcl-2 whereas the Epo treatment upregulated not only Bcl-2 but also Bcl-xL. This upregulation by Epo was not detected in atRA-differentiated cells, thus confirming the lack of the protective effect of Epo. As expected, assays with AG490, an inhibitor of Jak2, blocked the Epo action only in undifferentiated cells. This reduced neuroprotective function of Epo on SH-SY5Y differentiated cells could be explained at least in part by downregulation of the Epo receptor expression, which was observed in atRA-differentiated cells. This study shows differential cellular protection induced by Epo at two stages of SH-SY5Y differentiation. The results allow us to suggest that this differential cell behavior can be ascribed to the interaction between atRA and the signaling pathways mediated by Epo.
    Journal of Cellular Biochemistry 03/2010; 110(1):151-61. · 3.06 Impact Factor
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    ABSTRACT: Since the reversible phosphorylation of tyrosyl residues is a critical event in cellular signaling pathways activated by erythropoietin (Epo), attention has been focused on protein tyrosine phosphatases (PTPs) and their coordinated action with protein tyrosine kinases. The prototypic member of the PTP family is PTP1B, a widely expressed non-receptor PTP located both in cytosol and intracellular membranes via its hydrophobic C-terminal targeting sequence. PTP1B has been implicated in the regulation of signaling pathways involving tyrosine phosphorylation induced by growth factors, cytokines, and hormones, such as the downregulation of erythropoietin and insulin receptors. However, little is known about which factor modulates the activity of this enzyme. The effect of Epo on PTP1B expression was studied in the UT-7 Epo-dependent cell line. PTP1B expression was analyzed under different conditions by Real-Time PCR and Western blot, while PTP1B phosphatase activity was determined by a p-nitrophenylphosphate hydrolysis assay. Epo rapidly induced an increased expression of PTP1B which was associated with higher PTP1B tyrosine phosphorylation and phosphatase activity. The action of Epo on PTP1B induction involved Janus Kinase 2 (JAK2) and Phosphatidylinositol-3 kinase (PI3K). The results allow us to suggest for the first time that, besides modulating Epo/Epo receptor signaling, PTP1B undergoes feedback regulation by Epo.
    Cellular Physiology and Biochemistry 02/2007; 20(5):319-28. · 3.42 Impact Factor