RESUMEN
This study examines the relationship between a critical learning outcome of behavioral fluency and endurance, by comparing the effects of two practice procedures on multiplication facts two through nine. The first procedure, called whole time practice trial, consisted of an uninterrupted 1 minute practice time. The second procedure, endurance building practice trials, had three 20 second practice trials. A total of 3 students with attention deficit hyperactivity disorder participated. Results indicated that multiplication facts with the endurance building practice trials produced more efficient learning when compared to the whole time practice trial procedure for all 3 participants. Additionally, results show that even with the amount of practice time being equal, 1 minute in both conditions, on average participants practiced 30% more problems with the endurance building practice trials procedure than they did with the whole time practice trial procedure.
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Trastorno por Déficit de Atención con Hiperactividad , Aprendizaje , Conceptos Matemáticos , Práctica Psicológica , Humanos , Masculino , Pruebas Neuropsicológicas , Factores de TiempoRESUMEN
Breast cancer metastases develop in the bone more frequently than any other site and are a common cause of morbidity in the form of bone pain, pathological fractures, nerve compression and life-threatening hypercalcemia. Despite ongoing research efforts, the molecular and cellular mechanisms that regulate breast cancer cell homing to and colonization of the bone as well as resultant pathological bone alteration remain poorly understood. To identify key mediators promoting breast cancer metastasis to bone, we utilized an immunocompetent, syngeneic murine model of breast cancer metastasis employing the mammary tumor cell line NT2.5. Following intracardiac injection of NT2.5 cells in neu-N mice, metastases developed in the bone, liver and lung, closely mimicking the anatomical distribution of metastases in patients with breast cancer. Using an in vivo selection process, we established NT2.5 sublines demonstrating an enhanced ability to colonize the bone and liver. Genome-wide cDNA microarray analysis comparing gene expression between parental NT2.5 cells and established sublines revealed both known and novel mediators of bone metastasis and osteolysis, including the transcriptional co-activator CITED2. In further studies, we found that expression of CITED2 was elevated in human primary breast tumors and bone metastasis compared to normal mammary epithelium and was highest in breast cancer cell lines that cause osteolytic bone metastasis in animal models. In addition, reducing CITED2 expression in NT2.5 cells inhibited the establishment of bone metastasis and osteolysis in vivo, suggesting a potential role for CITED2 in promoting breast cancer bone metastasis.
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Neoplasias Óseas/patología , Neoplasias de la Mama/patología , Proteínas Represoras/genética , Transactivadores/genética , Animales , Neoplasias Óseas/secundario , Adhesión Celular/fisiología , División Celular/fisiología , Línea Celular Tumoral , ADN de Neoplasias/genética , Modelos Animales de Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Mamarias Experimentales/genética , Neoplasias Mamarias Experimentales/patología , Neoplasias Mamarias Experimentales/secundario , Ratones , Metástasis de la Neoplasia/patología , Análisis de Secuencia por Matrices de Oligonucleótidos , Osteólisis/patología , ARN Mensajero/genética , Proteínas Represoras/fisiología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/fisiología , Transactivadores/fisiología , Transcripción GenéticaRESUMEN
Approximately 30% of patients with renal cell carcinoma (RCC) develop bone metastasis, which is characterized by extensive osteolysis leading to severe bone pain and pathologic fracture. Although the mechanism of RCC-induced osteolysis is unknown, studies of bone metastasis have shown that tumor-induced changes in bone remodeling are likely mediated by alterations in the bone microenvironment. Here, we report the discovery of a novel osteoclast stimulatory factor secreted by RCC bone metastasis (RBM). Through microarray analysis, we found expression of the chemokine, macrophage inflammatory protein-1 delta (MIP-1 delta), to be increased in RBM versus patient-matched primary RCC tissues and confirmed this finding by quantitative reverse transcription-PCR (qRT-PCR) and ELISA (P < 0.05). Furthermore, MIP-1 delta expression in RBM tissues was significantly (P < 0.001) higher than in human bone marrow, suggesting a potential alteration of the bone microenvironment. The receptors for MIP-1 delta, CCR1 and CCR3, were expressed in both osteoclast precursors and mature, bone-resorbing osteoclasts as shown by qRT-PCR and Western analysis. In functional studies, MIP-1 delta stimulated chemotaxis of two osteoclast precursor cell types: murine bone marrow mononuclear cells (BM-MNC) and RAW 264.7 cells. Furthermore, MIP-1 delta treatment of murine calvaria caused increased bone resorption as determined by measurement of released calcium. Correspondingly, MIP-1 delta significantly enhanced osteoclast formation and activity in response to RANKL in both BM-MNC and RAW 264.7 cells. Taken together, these data suggest that MIP-1 delta expression is increased in RBM relative to RCC and bone marrow, and may promote RBM-induced osteolysis by stimulating the recruitment and differentiation of osteoclast precursors into mature osteoclasts.
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Huesos/patología , Carcinoma de Células Renales/metabolismo , Regulación Neoplásica de la Expresión Génica , Neoplasias Renales/patología , Proteínas Inflamatorias de Macrófagos/fisiología , Osteoclastos/metabolismo , Animales , Huesos/metabolismo , Carcinoma de Células Renales/patología , Diferenciación Celular , Movimiento Celular , Humanos , Neoplasias Renales/metabolismo , Leucocitos Mononucleares/metabolismo , Proteínas Inflamatorias de Macrófagos/química , Ratones , Metástasis de la Neoplasia , Ligando RANK/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Brain metastasis is the most commonly occurring intracranial tumor whose incidence seems to be increasing. With standard therapy, the average survival time of patients is approximately 8 months, and treatment often leads to neurologic dysfunction in long-term survivors, emphasizing the need for novel therapeutics. Clostridium perfringens enterotoxin (CPE) has recently been shown to rapidly and specifically destroy cancer cells expressing CPE receptors claudin-3 and claudin-4. Unfortunately, the utility of CPE is precluded by systemic toxicity because its receptors are expressed in numerous organs. Here, we provide the first preclinical evidence that CPE may be uniquely suited to the local treatment of brain metastasis. By immunohistochemical analysis, claudin-3 and claudin-4 were expressed frequently in metastases from breast (15 of 18), lung (15 of 20), and colon (12 of 14) carcinoma, and infrequently in metastases from renal cell carcinoma (2 of 16) and melanoma (2 of 16). In contrast, expression of claudin-3 and claudin-4 was absent in adjacent normal brain tissue. Further examination of the central nervous system (CNS) revealed low or undetectable levels of claudin-3 and claudin-4 in all regions tested by Western and immunohistochemical analysis. Treatment of breast cancer cell lines (MCF-7, MDA-MB-468, NT2.5-luc) and normal human astrocytes with CPE in vitro resulted in rapid and dose-dependent cytolysis exclusively in breast cancer cells, correlating with claudin-3 and claudin-4 expression. Moreover, intracranial CPE treatment significantly inhibited tumor growth and increased survival in two murine models of breast cancer brain metastasis, without any apparent local or systemic toxicity. These data suggest that CPE therapy may have efficacy against a wide variety of brain metastases without CNS toxicity.
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Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/secundario , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Carcinoma/tratamiento farmacológico , Carcinoma/patología , Enterotoxinas/uso terapéutico , Animales , Apoptosis/efectos de los fármacos , Astrocitos/metabolismo , Neoplasias de la Mama/mortalidad , Carcinoma/mortalidad , Claudina-3 , Claudina-4 , Evaluación Preclínica de Medicamentos , Femenino , Humanos , Proteínas de la Membrana/metabolismo , Ratones , Ratones Desnudos , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
UNLABELLED: Bone metastases develop in approximately 30% of patients with RCC, and the mechanisms responsible for this phenomenon are unknown. We found that TGF-beta1 stimulation of RCC bone metastasis cells promotes tumor growth and bone destruction possibly by stimulating paracrine interactions between tumor cells and the bone. INTRODUCTION: Bone metastasis is a frequent complication and causes marked morbidity in patients with renal cell carcinoma (RCC). Surprisingly, the specific mechanisms of RCC interaction with bone have been scarcely studied despite the inability to prevent or effectively treat bone metastasis. Bone is a reservoir for various growth factors including the pleiotropic cytokine TGF-beta1. TGF-beta1 has been shown to have tumor-supportive effects on advanced cancers and evidence suggests its involvement in promoting the development of breast cancer bone metastasis. Here, we studied the potential role of TGF-beta1 in the growth of RCC bone metastasis (RBM). MATERIALS AND METHODS: To inhibit TGF-beta1 signaling, RBM cells stably expressing a dominant-negative (DN) TGF-betaRII cDNA were generated. The in vivo effect of TGF-beta1 on RBM tumor growth and osteolysis was determined by histological and radiographic analysis, respectively, of athymic nude mice after intratibial injection of parental, empty vector, or DN RBM cells. The in vitro effect of TGF-beta1 on RBM cell growth was determined after TGF-beta1 treatment by MTT assay. RESULTS: TGF-beta1 and the TGF-beta receptors I and II (TGF-betaRI/II) were consistently expressed in both RBM tissues and cell lines. Inhibition of TGF-beta1 signaling in RBM cells significantly reduced tumor establishment and osteolysis observed in vivo after injection into the murine tibia, although no effect on tumor establishment was observed after injection of RBM cells subcutaneously or into the renal subcapsule. Treatment of five RBM cell lines with TGF-beta1 in vitro either had no effect (2/5) or resulted in a significant inhibition (3/5) of cell growth, suggesting that TGF-beta1 may promote RBM tumor growth indirectly in vivo. CONCLUSIONS: TGF-beta1 stimulation of RBM cells plays a role in promoting tumor growth and subsequent osteolysis in vivo, likely through the initiation of tumor-promoting paracrine interactions between tumor cells and the bone microenvironment. These data suggest that inhibition of TGF-beta1 signaling may be useful in the treatment of RBM.