Examinando por Autor "Matar, Pablo"

Mostrando 1 - 11 de 11
  • Miniatura
    ÍtemAcceso Abierto
    A Novel Synergistic Combination of Cyclophosphamide and Gene Transfer of Interleukin-12 Eradicates Colorectal Carcinoma in Mice
    (American Association for Cancer Research, 2009-11) Malvicini, Mariana; Rizzo, Miguel; Alaniz, Laura; Piñero, Federico; García, Mariana; Atorrasagasti, Catalina; Aquino, Jorge B.; Rozados, Viviana R.; Scharovsky, O. Graciela; Matar, Pablo; Mazzolini, Guillermo
    PURPOSE: Interleukin-12 (IL-12) is an immunostimulatory cytokine with potent antitumor effects in several animal models. However, serious toxicity has been associated with its systemic application in humans. Gene transfer has emerged as a tool to specifically express therapeutic genes into the tumor/peritumoral milieu, thus avoiding systemic toxicity. The aim of this study was to analyze whether subtherapeutic doses of an adenovirus encoding IL-12 (AdIL-12) might synergize with low immunopotentiating doses of cyclophosphamide in the treatment of colorectal carcinoma. EXPERIMENTAL DESIGN: The antitumor effect of combining a single low dose of cyclophosphamide with an intratumoral injection of AdIL-12 was evaluated in an in vivo murine colorectal carcinoma model. The immune responses achieved with different treatments were monitored, comparing the effect of combining both therapies with individual treatments. RESULTS: The combined therapy induced a complete tumor regression in >50% of mice in a synergistic fashion, and it significantly prolonged their survival. This strategy was superior to each single treatment in reducing both peripheral and splenic CD4+CD25+Foxp3+ regulatory T cells, increasing the number of activated dendritic cells, and inducing IFN-gamma-secreting CD4-positive T lymphocytes. Importantly, the combined treatment generated a powerful tumor-specific CTL response. Consistently, a significant reduction in IL-10 levels was found. Our data suggest that the combination of nontoxic doses of cyclophosphamide with AdIL-12 allows the generation of good antitumoral responses, thus avoiding undesired side effects of both agents. CONCLUSIONS: Our data strongly support the use of a combination of cyclophosphamide and AdIL-12 as a novel therapeutic strategy against colorectal carcinoma.
  • Miniatura
    ÍtemAcceso Abierto
    De la inmunovigilancia al escape tumoral: Historia de un enemigo con múltiples estrategias de resistencia y contra-ataque
    (Sociedad Española de Inmunología, 2006-04) Scharovsky, O. Graciela; Matar, Pablo; Zacarías Fluck, Mariano; Rico, María José; Rabinovich, Gabriel A.
    Tumors must circumvent the immune response of the host to become clinically detectable. For this purpose, malignant cells have devised multiple strategies to thwart immune attack. These mechanisms are suggested to conspire in advanced stages of cancer to limit the ability of the immune system to restrain the tumor and the effectiveness of immunotherapy strategies to successfully eradicate malignant cells. From tumor biology to cancer immunotherapy and back again, we will summarize here some of the most important mechanisms used by tumors to evade the immune response and their potential impact in the design of cancer immunotherapy strategies.
  • Miniatura
    ÍtemAcceso Abierto
    Differential production of angiostatin by concomitant antitumoral resistance-inducing cancer cells
    (Wiley, 2002-05-02) Binda, María Mercedes; Matar, Pablo; González, Alejandro D.; Rozados, Viviana R.; Gervasoni, Silvia I.; Scharovsky, O. Graciela; Bonfil, R. Daniel
    The phenomenon by which tumor-bearing hosts are capable of inhibiting secondary tumor implants or metastases, known as concomitant antitumoral resistance (CAR), is presumably due to antiangiogenesis at places distant from the primary tumor. Although angiostatin, a potent inhibitor of angiogenesis, has been reported to be one of the factors responsible for suppressing the growth of secondary tumors in mice bearing previous tumors, it has not been definitively proven yet. With the aim of investigating whether CAR-inducing cancer cells display a differential angiostatin production and to support the role ascribed to that molecule concerning the inhibition of secondary tumor implants, 5 tumor models with different CAR-inducing capacities were studied herein. One of the 2 human lung cancer cell lines analyzed revealed a strong CAR against secondary s.c. tumor implants in nude mice, and 2 of 3 of the murine mammary tumors used exhibited inhibitory effect on secondary s.c. and i.v. tumor inoculations in syngeneic hosts. Since angiostatin is a proteolytic fragment from plasminogen, we examined by Western blot the ability of all conditioned media collected from the tumor cells studied to convert plasminogen to angiostatin. An association between in vivo generation of CAR and in vitro conversion of plasminogen into angiostatin was found. Since different enzymatic mechanisms were described to explain the generation of angiostatin, we also studied gelatinase and urokinase-type plasminogen activator secretion in conditioned media by zymography. The conversion of plasminogen into angiostatin by conditioned media was mainly inhibited by broad-spectrum serine proteinase inhibitors, suggesting a possible role for 1 or more enzymes of that group in the process. These findings suggest the existence of a differential angiostatin generation by CAR-inducing cancer cells, providing additional support to previous data obtained by other authors.
  • Miniatura
    ÍtemAcceso Abierto
    Hsp25 and Hsp70 in rodent tumors treated with doxorubicin and lovastatin
    (Springer, 2003-01) Ciocca, Daniel R.; Rozados, Viviana R.; Cuello Carrión, F. Darío; Gervasoni, Silvia I.; Matar, Pablo; Scharovsky, O. Graciela
    Heat shock protein 27 (Hsp27) and Hsp70 have been involved in resistance to anticancer drugs in human breast cancer cells growing in vitro and in vivo. In this study, we examined the expression of Hsp25 (the rodent homologue to human Hsp27) and Hsp70 in 3 different rodent tumors (a mouse breast carcinoma, a rat sarcoma, and a rat lymphoma maintained by subcutaneous passages) treated in vivo with doxorubicin (DOX) and lovastatin (LOV). All tumors showed massive cell death under control untreated conditions, and this massive death increased after cytotoxic drug administration. In this study, we show that this death was due to classic apoptosis. The tumors also showed isolated apoptotic cells between viable tumor cells, and this occurred more significantly in the lymphoma. The tumor type that was more resistant to cell death was the sarcoma, and this was found in sarcomas growing both under control conditions and after cytotoxic drug administration. Moreover, sarcomas showed the highest expression levels of Hsp25 in the viable tumor cells growing under untreated conditions, and these levels increased after DOX and LOV administration. After drug treatment, only sarcoma tumor cells showed a significant increase in Hsp70. In other words, sarcomas were the tumors with lower cell death, displayed a competent Hsp70 and Hsp25 response with nuclear translocation, and had the highest levels of Hsp25. In sarcomas, Hsp25 and Hsp70 were found in viable tumor cells located around the blood vessels, and these areas showed the most resistant tumor cell phenotype after chemotherapy. In addition, Hsp25 expression was found in endothelial cells as unique feature revealed only in lymphomas. In conclusion, our study shows that each tumor type has unique features regarding the expression of Hsp25 and Hsp70 and that these proteins seem to be implicated in drug resistance mainly in sarcomas, making these model systems important to perform more mechanistic studies on the role of Hsps in resistance to certain cytotoxic drugs.
  • Miniatura
    ÍtemAcceso Abierto
    Immunotherapy for liver tumors: present status and future prospects
    (BioMed Central, 2009-03-06) Matar, Pablo; Alaniz, Laura; Rozados, Viviana R.; Aquino, Jorge B.; Malvicini, Mariana; Atorrasagasti, Catalina; Gidekel, Manuel; Silva, Marcelo; Scharovsky, O. Graciela; Mazzolini, Guillermo
    Increasing evidence suggests that immune responses are involved in the control of cancer and that the immune system can be manipulated in different ways to recognize and attack tumors. Progress in immune-based strategies has opened new therapeutic avenues using a number of techniques destined to eliminate malignant cells. In the present review, we overview current knowledge on the importance, successes and difficulties of immunotherapy in liver tumors, including preclinical data available in animal models and information from clinical trials carried out during the lasts years. This review shows that new options for the treatment of advanced liver tumors are urgently needed and that there is a ground for future advances in the field.
  • Miniatura
    ÍtemAcceso Abierto
    Inmunomodulación y antiangiogénesis en la terapéutica oncológica. De la investigación básica a la clínica
    (Fundación Revista Medicina (Buenos Aires), 2012-02) Scharovsky, O. Graciela; Matar, Pablo; Rozados, Viviana R.; Rico, María José; Zacarías Fluck, Mariano; Mainetti, Leandro Ernesto; Fernández Zenobi, María Virginia
    La investigación básica y pre-clínica en oncología celular y molecular son pilares fundamentales en los que se apoyan la mayoría de los adelantos en la terapéutica del cáncer. Los hallazgos obtenidos y su aplicación en la práctica clínica constituyen la causa del avance sostenido en el tratamiento de la enfermedad neoplásica. El objetivo de este trabajo es resumir y discutir los resultados pre-clínicos en inmunomodulación y anti-angiogénesis para el tratamiento de diversos tipos de tumores, obtenidos en nuestro Instituto durante los últimos 15 años, y la posterior traslación y aplicación del conocimiento experimental en un Ensayo Clínico Fase I/II. Se describen los resultados que contribuyeron a descifrar los mecanismos de acción de la inmunomodulación antimetastásica con ciclofosfamida, la quimioterapia metronómica con diferentes drogas únicas o combinaciones, y finalmente el diseño y resultados preliminares de un ensayo clínico de quimioterapia metronómica para pacientes con cáncer de mama avanzado.
  • Miniatura
    ÍtemAcceso Abierto
    Lovastatin enhances the antitumoral and apoptotic activity of doxorubicin in murine tumor models
    (Spandidos (Grecia), 2008-05) Rozados, Viviana R.; Hinrichsen, Lucila Isabel; Binda, María Mercedes; Gervasoni, Silvia I.; Matar, Pablo; Bonfil, Daniel R.; Scharovsky, O. Graciela
    Despite its effectiveness as an antineoplastic drug, doxorubicin (DOX) is usually associated with cardiotoxicity. Lovastatin (LOV), a hypolipidemic agent used in the clinic, has been demonstrated to have antitumoral and antimetastatic effects in murine models. Since the two agents arrest tumor cells in different phases of the cell cycle and induce apoptosis, the goal of this study was to examine the efficacy of a combination therapy with LOV and low doses of DOX, in an attempt to obtain an improved antitumoral effect devoid of toxicity, by using a rat B-cell lymphoma and a mouse mammary tumor. In the two models, the combined treatment showed a synergistic antitumoral effect, which is mainly ascribed to an increased apoptotic response elicited by a LOV/DOX combination than either agent alone. The therapeutic benefit demonstrated by the combination treatment is further emphasized by the lack of toxicity.
  • Miniatura
    ÍtemAcceso Abierto
    Metronomic therapy with cyclophosphamide induces rat lymphoma and sarcoma regression, and is devoid of toxicity
    (Oxford University Press, 2004-10) Rozados, Viviana R.; Sánchez, Andrea M.; Gervasoni, Silvia I.; Berra, Héctor H.; Matar, Pablo; Scharovsky, O. Graciela
    BACKGROUND: Our aim was to investigate the clinical efficacy and toxicity of metronomic administration of low-dose cyclophosphamide (Cy) in lymphoma and sarcoma rat tumour models. METHODS: Adult inbred rats were challenged with lymphoma TACB and sarcoma E100 s.c. on day 0. Animals were divided into two groups: group I, control, injected with saline three times a week; and group II, treated with Cy 10 mg/kg three times a week, from day 10 until the tumour was non-palpable, or 5 mg/kg three times a week from day 7. Tumours were measured and animals were weighed twice weekly. Periodic blood samples were taken for determination of urea, creatinine, serum glutamic-oxaloacetic transaminase, lactate dehydrogenase and haematological parameters. RESULTS: The administration of low-dose Cy eradicated established rat lymphomas and sarcomas; there was neither metastatic growth nor recurrence at primary sites for 100% of the lymphomas and 83% of the sarcomas. In addition, the treatment did not cause weight loss, and was devoid of haematological, cardiac, hepatic and renal toxicity. CONCLUSIONS: Metronomic administration of Cy at low doses on a thrice weekly schedule to already grown rat lymphomas and sarcomas demonstrated itself to be a successful antitumour therapy that did not cause weight loss and was devoid of haematological, cardiac, hepatic and renal toxicity.
  • Miniatura
    ÍtemAcceso Abierto
    Modulation of IL-10/IL-10R expression by mafosfamide, a derivative of 4-hydroxycyclophosphamide, in a rat B-cell lymphoma
    (Sociedad Latinoamericana de Microscopía Electrónica. Centro Regional de Investigaciones Científicas y Tecnológicas (Mendoza, Argentina), 2012-08) Rico, María José; Matar, Pablo; Scharovsky, O. Graciela
    We have already shown that IL-10 plays an important role in immunosuppression and metastatic dissemination in the rat B-cell lymphoma L-TACB model. It was suggested that the up-regulation of IL-10 production and IL-10 receptor (IL-10R) expression would be part of the transition from primary tumor to metastatic phenotype and that IL-10, besides its immunosuppressive activity, may act as a growth factor for metastatic L-TACB cells. The treatment of L-TACB-bearing rats with a single low-dose cyclophosphamide decreased IL-10 production, reverted immunosuppression and induced the immunologic rejection of tumor metastasis without any effect on primary tumor growth. Our current aim was to investigate the effects of cyclophosphamide on the expression of IL-10 and IL-10R on primary and metastatic L-TACB cells. Considering that cyclophosphamide is a prodrug, we used mafosfamide, a compound that yields in vitro the same active metabolites as cyclophosphamide does in vivo. Mafosfamide induced down-regulation of IL-10 production and IL-10R expression on metastatic cells and, concomitantly, inhibited metastatic cell proliferation. We suggest that mafosfamide would inhibit the regulatory loop mediated by the IL-10/IL-10R system and, as a consequence, metastatic cell proliferation. These results may have a considerable impact on the design of new therapies for metastatic lymphomas.
  • Miniatura
    ÍtemAcceso Abierto
    Regulatory T cells but not NKT I cells are modulated by a single low-dose cyclophosphamide in a B cell lymphoma tumor-model
    (MORION LLC, 2012-03) Rico, María José; Rozados, Viviana R.; Mainetti, Leandro Ernesto; Zacarías Fluck, Mariano; Matar, Pablo; Scharovsky, O. Graciela
    Aim: Experimental and clinical studies showed that the administration of cyclophosphamide (Cy) in low doses leads to an enhancement of the antitumor immune response. Our objective was to study the modulation, if any, by low dose Cy, of T regulatory (Treg) and natural killer T (NKT) I cells, two cell populations of the innate immune response with opposing effects on the tumors, in a rat B cell lymphoma model. Methods: Inbred e rats were challenged s.c. with L-TACB lymphoma and on day 14 animals were distributed in two groups. Treated: injected i.p. with cyclophosphamide (10mg/kg of body weight) and Control: injected i.p. with saline. Blood samples were taken from days 0 to 21 and the percentage of T regulatory and natural killer T I cells were determined by flow cytometry. Results: We found that the increase of natural and inducible T regulatory cells of peripheral blood achieved during tumor growth was significantly downregulated by cyclophosphamide. On the contrary, natural killer T I cells were not modulated by the treatment. Conclusion: The antimetastatic effect of a single low dose of Cy would be due, at least in part, to downregulation of natural and inducible T regulatory cells.
  • Miniatura
    ÍtemAcceso Abierto
    The Immune Response and the Therapeutic Effect of Metronomic Chemotherapy With Cyclophosphamide
    (Cognizant Communication Corporation, 2010-11-01) Rozados, Viviana R.; Mainetti, Leandro Ernesto; Rico, María José; Zacarías Fluck, Mariano; Matar, Pablo; Scharovsky, O. Graciela
    Metronomic chemotherapy (MCT) is a novel therapeutic strategy for cancer treatment endowed with an antiangiogenic effect. It refers to regular administration of low doses of cytotoxic drugs, with minimal or no drug-free breaks. Previously, we demonstrated the immunomodulating activity of a single low-dose of cyclophosphamide (Cy) and the antitumor effect of MCT with Cy on established rat lymphomas and sarcomas. Here, we examined whether the immune response is responsible for the antitumor effect of MCT with Cy on L-TACB lymphoma. Inbred e rats and nude mice were subcutaneously challenged with L-TACB. After 7 days, they were distributed into two experimental groups: 1) treated animals, which were injected IP with Cy (10 mg/kg body weight) three times per week, and 2) control animals, which received IP saline injections. Exponential growth and decay and tumor doubling time were calculated. Also, serum IL-10 levels were measured. One hundred percent of treated rats showed tumor regression versus 0% of control rats. The increase of tumor-induced IL-10 levels was reverted by the treatment with Cy. On the other hand, there were no tumor regressions, in treated or control nude mice. However, the tumor doubling times of treated nude mice were significantly higher than those of control mice, implying that other antitumor mechanism(s), independent of the adaptive immune response, might be taking place. Our present results indicate that modulation of the immune response would be involved in the antitumor effect of MCT with Cy, because the absence of the specific immune response impairs, at least in part, its therapeutic effect in a lymphoma tumor model.