Antiproliferative effect of mifepristone (RU486) on human neuroblastoma cells (SK-N-SH): in vitro and in vivo studies

RU486 (mifepristone), a glucocorticoid and progesterone receptor antagonist, has been reported to exert antiproliferative effects on tumor cells. Experiments were performed to analyze the effects of RU486 on the proliferation of the human neuroblastoma, both in vitro and in vivo, using the human neuroblastoma SK-N-SH cell line. The exposure in vitro of SK-N-SH cells to RU486 revealed a dose-dependent inhibition of 3H-thymidine incorporation due to a rapid but persistent inhibition of MAPKinase activity and ERK phosphorylation. A significant decrease of SK-N-SH cell number was evident after 3, 6, and 9 days of treatment (up to 40% inhibition), without evident cell death. The inhibitory effect exerted by RU486 was not reversed by the treatment of the cells with dexamethasone or progesterone. Moreover, RU486 induced a shift in SK-N-SH cell phenotypes, with an almost complete disappearance of the neuronal-like and a prevalence of the epithelial-like cell subtypes. Finally, the treatment with RU486 of nude mice carrying a SK-N-SH cell xenograft induced a strong inhibition (up to 80%) of tumor growth. These results indicated a clear effect of RU486 on the growth of SK-N-SH neuroblastoma cells that does not seem to be mediated through the classical steroid receptors. RU486 acted mainly on the more aggressive component of the SK-N-SH cell line and its effect in vivo was achieved at a concentration already used to inhibit oocyte implantation.

Dexamethasone blocks the migration of the human neuroblastoma cell line SK-N-SH

Glucocorticoids (Gc) influence the differentiation of neural crest-derived cells such as those composing sympathoadrenal tumors like pheochromocytomas, as well as neuroblastomas and gangliomas. In order to obtain further information on the effects of Gc on cells evolving from the neural crest, we have used the human neuroblastoma cell line SK-N-SH to analyze: 1) the presence and the binding characteristics of Gc receptors in these cells, 2) the effect of dexamethasone (Dex) on the migration of SK-N-SH cells, and 3) the effect of Dex on the organization of the cytoskeleton of SK-N-SH cells. We show that: 1) receptors that bind [³H]-Dex with high affinity and high capacity (Kd of 9.6 nM, Bmax of 47 fmol/mg cytosolic protein, corresponding to 28,303 sites/cell) are present in cytosolic preparations of SK-N-SH cells, and 2) treatment with Dex (in the range of 10 nM to 1 æM) has an inhibitory effect (from 100 percent to 74 and 43 percent, respectively) on the chemotaxis of SK-N-SH cells elicited by fetal bovine serum. This inhibition is completely reversed by the Gc receptor antagonist RU486 (1 æM), and 3) as demonstrated by fluorescent phalloidin-actin detection, the effect of Dex (100 nM) on SK-N-SH cell migration is accompanied by modifications of the cytoskeleton organization that appear with stress fibers. These modifications did not take place in the presence of 1 æM RU486. The present data demonstrate for the first time that Dex affects the migration of neuroblastoma cells as well as their cytoskeleton organization by interacting with specific receptors. These findings provide new insights on the mechanism(s) of action of Gc on cells originating in the neural crest.

Enfermedad celiaca y HLA en una poblacion hospitalaria del Uruguay. / Celiac disease and HLA in an Uruguayan hospital population

Desde que fue descrita, la asociacion del antigeno HLA-B8 con la enfermedad celiaca ha sido confirmado por muchos autores. Estudiamos 19 pacientes, no emparentados, con enfermedad celiaca y 64 controles. Sus edades oscilaban entre 18 meses y 18 anos. El comienzo de la enfermedad fue durante la infancia. Se determinaron 12 antigenos de locus A y 13 del locus B, usando la tecnica NIH de microlinfotoxidad. El grado de asociacion fue computado por el riesgo relativo y los resultados fueron estadisticamente evaluados por el Chi 2.Se demonstro mayor frecuencia solo en la del HLA-A29. Nuestros resultados no muestran una mayor incidencia para el HLA-B8 encontrados por otros autores, ni una incidencia mayor para el HLA-B12, sin embargo el HLA-B7 no fue detectado en nuestros pacientes. La decision final de que el HLA-A29 se asocia a la enfermedad celiaca en nuestra poblacion requerira el analisis de una muestra mayor

Reflujo gastro esofagico en pediatria. / Gastroesophageal reflux in pediatrics

Se estudiaron 15 ninos con reflujo gastro esofagico. Sus manifestaciones clinicas predominantes fueron cuadros respiratorios prolongados y recidivantes o vomitos. La edad media de presentacion de los sintomas fue de 6 meses. La edad media de diagnostico fue de 9 meses. Las tecnicas empleadas para el diagnostico fueron: el estudio radiologico del esofago gastroduodeno, la manometria esofagica, la esofagoscopia con biopsia, y el centellograma con tecnesio. Los pacientes recibieron tratamiento postural, antiacidos y dieta durante un lapso de seis meses. Catorce de 15 pacientes evolucionaron a la desaparicion de los sintomas. El pronostico estuvo condicionado a la precocidad del diagnostico y tratamiento