Recidiva tardía de insulinoma. Asociación con otras patologías

RESUMEN El insulinoma es un tumor neuroendocrino que se caracteriza por la producción de insulina. En individuos con MEN representa entre el 10 y el 30% de los tumores pancreáticos. Las metástasis son poco frecuentes. Presentamos el caso de una recidiva de un tumor productor de insulina después de varios años de la primera cirugía. La presencia de otras lesiones sugería un posible síndrome MEN1 aunque el estudio genético fue negativo. El hecho de que resultase negativo no descarta la posibilidad de que la paciente padezca el síndrome dado que hasta un 5-25% puede no tener mutación en dicho gen. El manejo del insulinoma a veces es complejo. Everolimus puede ser una opción de tratamiento en estos pacientes.

ABSTRACT Insulinoma is a pancreatic neuroendocrine tumor characterized by the production of insulin and represents 10 to 30% of pancreatic tumors in individuals with MEN 1. The metastases are rare. We present a recurrent pancreatic neuroendocrine tumor producing insulin after several years of the first surgery. The presence of other lesions suggests the possibility of a MEN1 syndrome; even the genetic study was negative. This fact does not rule out that the patient suffers from the syndrome since up to 5-25% ofthe reported cases with MEN1 syndrome may not have mutations. Management of these tumors may be complex Everolimus is a treatment option in these patients.

Microvesicles: ROS scavengers and ROS producers.

This review analyzes the relationship between microvesicles and reactive oxygen species (ROS). This relationship is bidirectional; on the one hand, the number and content of microvesicles produced by the cells are affected by oxidative stress conditions; on the other hand, microvesicles can directly and/or indirectly modify the ROS content in the extra- as well as the intracellular compartments. In this regard, microvesicles contain a pro-oxidant or antioxidant machinery that may produce or scavenge ROS: direct effect. This mechanism is especially suitable for eliminating ROS in the extracellular compartment. Endothelial microvesicles, in particular, contain a specific and well-developed antioxidant machinery. On the other hand, the molecules included in microvesicles can modify (activate or inhibit) ROS metabolism in their target cells: indirect effect. This can be achieved by the incorporation into the cells of ROS metabolic enzymes included in the microvesicles, or by the regulation of signaling pathways involved in ROS metabolism. Proteins, as well as miRNAs, are involved in this last effect.

Hydrogen peroxide down-regulates inositol 1,4,5-trisphosphate receptor content through proteasome activation.

Hydrogen peroxide (H(2)O(2)) is implicated in the regulation of signaling pathways leading to changes in vascular smooth muscle function. Contractile effects produced by H(2)O(2) are due to the phosphorylation of myosin light chain kinase triggered by increases in intracellular calcium (Ca(2+)) from intracellular stores or influx of extracellular Ca(2+). One mechanism for mobilizing such stores involves the phosphoinositide pathway. Inositol 1,4,5-trisphosphate (IP(3)) mobilizes intracellular Ca(2+) by binding to a family of receptors (IP(3)Rs) on the endoplasmic-sarcoplasmic reticulum that act as ligand-gated Ca(2+) channels. IP(3)Rs can be rapidly ubiquitinated and degraded by the proteasome, causing a decrease in cellular IP(3)R content. In this study we show that IP(3)R(1) and IP(3)R(3) are down-regulated when vascular smooth muscle cells (VSMC) are stimulated by H(2)O(2), through an increase in proteasome activity. Moreover, we demonstrate that the decrease in IP(3)R by H(2)O(2) is accompanied by a reduction in calcium efflux induced by IP(3) in VSMC. Also, we observed that angiotensin II (ANGII) induces a decrease in IP(3)R by activation of NADPH oxidase and that preincubation with H(2)O(2) decreases ANGII-mediated calcium efflux and planar cell surface area in VSMC. The decreased IP(3) receptor content observed in cells was also found in aortic rings, which exhibited a decreased ANGII-dependent contraction after treatment with H(2)O(2). Altogether, these results suggest that H(2)O(2) mediates IP(3)R down-regulation via proteasome activity.

Kinase-dependent, retinoic acid receptor-independent up-regulation of cyclooxygenase-2 by all-trans retinoic acid in human mesangial cells.

BACKGROUND AND PURPOSE: Preliminary results in human mesangial cells (MC) suggested that all-trans retinoic acid (ATRA) increased the expression of COX-2 and the production of prostaglandin E2 (PGE2), a PG with anti-inflammatory effects in MC. The aim of this work is to confirm that ATRA increases the expression of COX-2 in MC and to examine the mechanisms involved. EXPERIMENTAL APPROACH: Cultured MC were treated with ATRA. COX expression and kinase activity were analyzed by Western blot. Transcriptional mechanisms were analyzed by Northern blot, RT-PCR and promoter assays. KEY RESULTS: COX-2 and COX-1 expression and PGE2 production were increased by ATRA. COX-2 played a role in PGE2 production as production was only partially inhibited by COX-1 inhibitor SC-560. COX-2 up-regulation by ATRA was due to transcriptional mechanisms as pre-incubation with actinomycin D abolished it and ATRA increased the expression of COX-2 mRNA and the activity of a human COX-2 promoter construct, whereas post-transcriptional mechanisms were not found. Retinoic acid receptors (RAR) were not involved in the up-regulation of COX-2 by ATRA since it was not inhibited by RAR-pan-antagonists and the RAR-pan-agonist TTNPB did not up-regulate COX-2. Instead ATRA might act through a sustained activation of extracellular signal-regulated kinase 1/2 (ERK1/2) since up-regulation of COX-2 was prevented by inhibition of the activation of ERK1/2 with PD098059. Also ERK1/2, as well as downstream signalling proteins from ERK1/2, remained phosphorylated when COX-2 increased 24 h later. CONCLUSIONS AND IMPLICATIONS: These results highlight the relevance of RAR-independent mechanisms to the biological effects of ATRA.

Vitamin A active metabolite, all-trans retinoic acid, induces spinal cord sensitization. I. Effects after oral administration.

BACKGROUND AND PURPOSE: Retinoic acid is an active metabolite of vitamin A involved in the modulation of the inflammatory and nociceptive responses. The aim of the present study was to analyze the properties of spinal cord neuronal responses of male Wistar rats treated with all-trans retinoic acid (ATRA) p.o. in the normal situation and under carrageenan-induced inflammation. We also studied the expression and distribution of cyclooxygenases (COX) in the spinal cord. EXPERIMENTAL APPROACH: Properties of spinal cord neurons were studied by means of the single motor unit technique. The expression of COX enzymes in the spinal cord was assessed by Western blot analysis and immunohistochemistry. KEY RESULTS: Intensity thresholds for mechanical and electrical stimulation (C-fibers) were significantly lower in animals treated with ATRA than vehicle, either in normal rats or in rats with inflammation. The size of cutaneous receptive fields was also larger in animals treated with ATRA in the normal and inflammatory conditions. The expression of COX-2 enzyme, but not COX-1, was significantly higher in animals treated with ATRA. COX-2 labeling was observed in dorsal horn cells and in ventral horn motoneurons. CONCLUSIONS AND IMPLICATIONS: In conclusion, the oral treatment with ATRA in rats induces a sensitization-like effect on spinal cord neuronal responses similar to that observed in animals with inflammation and might explain the enhancement of allodynia and hyperalgesia observed in previously published behavioral experiments. The mechanism of action involves an over-expression of COX-2, but not COX-1, in dorsal and ventral horn areas of the lumbar spinal cord.

Vitamin A active metabolite, all-trans retinoic acid, induces spinal cord sensitization. II. Effects after intrathecal administration.

BACKGROUND AND PURPOSE: In our previous study (see accompanying paper) we observed that all-trans retinoic acid (ATRA) p.o. induces changes in spinal cord neuronal responses similar to those observed in inflammation-induced sensitization. In the present study we assessed the it. effects of ATRA, and its mechanisms of action. EXPERIMENTAL APPROACH: The effects of all drugs were studied after it. administration in nociceptive withdrawal reflexes using behavioural tests in awake male Wistar rats. KEY RESULTS: The administration of ATRA in normal rats induced a dose-dependent enhancement of nociceptive responses to noxious mechanical and thermal stimulation, as well as responses to innocuous stimulation. The intensity of the responses was similar to that observed in non-treated animals after carrageenan-induced inflammation. The effect induced by ATRA was fully prevented by the previous administration of the retinoic acid receptor (RAR) pan-antagonist LE540 but not by the retinoid X receptor (RXR) pan-antagonist HX531, suggesting a selective action on spinal cord RARs. The COX inhibitor dexketoprofen and the interleukin-1 receptor antagonist IL-1ra inhibited ATRA effect. The results indicate that COX and interleukin-1 are involved in the effects of ATRA in the spinal cord, similar to that seen in inflammation. CONCLUSIONS AND IMPLICATIONS: In conclusion, ATRA induces changes in the spinal cord similar to those observed in inflammation. The sensitization-like effect induced by ATRA was mediated by RARs and associated with a modulation of COX-2 and interleukin-1 activities. ATRA might be involved in the mechanisms underlying the initiation and/or maintenance of sensitization in the spinal cord.

[All-trans retinoic acid induces apoptosis in human mesangial cells: involvement of stress activated p38 kinase]. / El ácido retinoico todo-trans induce apoptosis en células mesangiales humanas: implicación de la quinasa activada por estrés p38.

All-trans retinoic acid (AR-t) is used for treating acute promyelocytic leukemia and renal cell carcinoma and it also has therapeutic value in several animal models of renal disease. Among its renal targets, mesangial cells have been widely studied: they have both retinoic acid receptors (RAR) and retinoid X receptors (RXR) and the cell growth is inhibited when human mesangial cells are incubated with 1-10 microM AR-t. Although his effect has been related with the antiproliferative action of AR-t, there are no studies on the involvement of apoptosis in AR-t induced cell growth when higher concentrations of retinoid are used. Our studies show that 25 microM AR-t triggers mesangial cell apoptosis assessed by light and fluorescence microscopy (Giemsa stain and acridine orange stain, respectively), DNA electrophoresis, flow cytometry (annexin-V) and immunocytochemistry (TUNEL). AR-t induced apoptosis was not inhibited by preincubation with the RXR pan-antagonist HX531 nor with the RAR pan-antagonist AGN 193109, this suggesting RAR and RXIR are not involved in AR-t induced cell death. Previous results of our group showed that ERK (extracellular regulated kinase) and INK (c-Jun kinase), two members of the MAP (mitogen activated protein) kinase family, are involved in non apoptotic effects of AR-t on mesangial cells. Therefore we focussed on the stress activated p38 kinase, the third member of the MAPK family, to investigate its involvement in AR-t induced apoptosis. The results confirmed a role of p38 since: 1) preincubation with B5203589, a p38 inhibitor, inhibited ARA induced apoptosis; 2) incubation with AR-t induced p38 phosphorilation after few minutes and p38 remained phosphorilated for at least 8 hours and 3) AR-t induced p38 phosphorilation was inhibited by SB203589. These data suggest that AR-t might have toxic side effects on the kidney but also suggest that AR-t could be an useful inhibitor of pathological mesangial cell expansion.

El ácido retinoico todo-trans induce apoptosis en células mesangiales humanas: implicación de la quinasa activada por estrés p38 / All-trans retinoic acid induces apoptosis in human mesangial cells: involvement of stress activated p38 kinase

El ácido retinoico todo-trans (AR-t) se utiliza en clínica en el tratamiento de la leucemiapromielocítica aguda y el cáncer renal. También presenta efecto terapéutico endiversas formas de enfermedad renal experimental. Las células mesangiales son una delas dianas farmacológicas de AR-t mejor estudiadas: presentan receptores de ácido retinoico(RAR) y receptores X de retinoides (RXR) y el AR-t, a concentraciones entre 1 y 10µM, inhibe su crecimiento. Este efecto se ha relacionado con la acción antiproliferativadel AR-t, aunque no se ha estudiado la participación de mecanismos apoptóticos cuandose utilizan mayores concentraciones de AR-t. El presente trabajo demuestra que AR-t25 µM induce apoptosis de células mesangiales humanas en cultivo, caracterizada porestudios de microscopía óptica y de fluorescencia (tinciones de Giemsa y naranja deacridina, respectivamente), electroforesis del ADN fragmentado, citometría de flujo(anexina-V/ioduro de propidio) e inmunocitoquímica (TUNEL). Ni HX531 (pan-antagonistaRXR), ni AGN193109 (pan-antagonista RAR) redujeron el grado de muerte celularinducido por el AR-t, lo que sugiere un mecanismo independiente de receptores. Resultadosprevios de nuestro grupo indican que dos de los tres miembros de las quinasasactivadas por mitógenos (MAP), ERK (quinasa regulada por estímulos extracelulares) yJNK (quinasa de c-Jun), están implicados en efectos no apoptóticos del AR-t en célulasmesangiales. Nos centramos, pues, en el potencial pro-apoptótico del tercer miembro,la quinasa activada por estrés p38. Confirmamos su implicación en la apoptosis inducidapor el AR-t porque: 1) su inhibidor farmacológico, SB203580, previno dicha apoptosis2) El AR-t indujo en pocos minutos la fosforilación de p38, manteniéndose fosforiladadurante las 8 horas posteriores; y 3) dicha fosforilación se inhibió por preincubación conSB203580. Estos datos sugieren una posible toxicidad renal del AR-t, pero también suutilidad para controlar la proliferación patológica de células mesangiales

All-trans retinoic acid (AR-t) is used for treating acute promyelocytic leukemia andrenal cell carcinoma and it also has therapeutic value in several animal models of renaldisease. Among its renal targets, mesangial cells have been widely studied: they haveboth retinoic acid receptors (RAR) and retinoid X receptors (RXR) and the cell growthis inhibited when human mesangial cells are incubated with 1-10 µM AR-t. Althoughhis effect has been related with the antiproliferative action of AR-t, there are no studieson the involvement of apoptosis in AR-t induced cell growth when higher concentrationsof retinoid are used. Our studies show that 25 µM AR-t triggers mesangial cellapoptosis assessed by light and fluorescence microscopy (Giemsa stain and acridineorange stain, respectively), DNA electrophoresis, flow cytometry (annexin-V) andimmunocytochemistry (TUNEL). AR-t induced apoptosis was not inhibited by preincubationwith the RXR pan-antagonist HX531 nor with the RAR pan-antagonist AGN193109, this suggesting RAR and RXIR are not involved in AR-t induced cell death.Previous results of our group showed that ERK (extracellular regulated kinase) andJNK (c-Jun kinase), two members of the MAP (mitogen activated protein) kinasefamily, are involved in non apoptotic effects of AR-t on mesangial cells. Therefore wefocussed on the stress activated p38 kinase, the third member of the MAPK family, toinvestigate its involvement in AR-t induced apoptosis. The results confirmed a role ofp38 since: 1) preincubation with SB203589, a p38 inhibitor, inhibited ARA inducedapoptosis; 2) incubation with AR-t induced p38 phosphorilation after few minutesand p38 remained phosphorilated for at least 8 hours and 3) AR-t induced p38 phosphorilationwas inhibited by SB203589. These data suggest that AR-t migth have toxicside effects on the kidney but also suggest that AR-t could be an useful inhibitor of pathologicalmesangial cell expansion

The oral administration of retinoic acid enhances nociceptive withdrawal reflexes in rats with soft-tissue inflammation.

OBJECTIVE AND DESIGN: To study the involvement of all-trans retinoic acid (ATRA) in the development and maintenance of inflammatory pain. SUBJECTS: Adult male Wistar rats and murine neuro2a and human SH-SY5Y neuroblastoma cells. TREATMENT: Soft-tissue inflammation was induced by the intraplantar administration of 100 microl of carrageenan lambda. The oral treatment with either ATRA or vehicle lasted for seven days and consisted in a dose of 15 mg/kg the first two days and a dose of 10 mg/kg the following five days. Neuroblastoma cells were incubated for 16 h with ATRA. METHODS: Rats were tested twice daily for intensity and evolution of withdrawal reflexes evoked by mechanical and thermal stimulation. The expression of COX enzymes was studied in spinal cords and neuroblastoma cells by western blot. RESULTS: The animals treated with ATRA showed a significantly more intense development of mechanical allodynia (p < 0.01), mechanical hyperalgesia (p < 0.01), thermal hyperalgesia (p < 0.001) and reduction of threshold for mechanical (29 +/- 4 vs. 60 +/- 6 mN, p < 0.001) and thermal stimulation (12 +/- 0.3 vs. 8.4 +/- 0.3 s, p < 0.001) than control animals. Recovery to mechanical baseline data was slower in animals treated with ATRA, the main difference was observed in the test carried out on day 2, p.m. In neuroblastoma cells incubated with ATRA, a concentration-dependent increase in the expression of COX-2 protein was observed. Changes in the expression of COX-1 enzyme were not clear. An increase in COX-2 expression in the lumbar spinal cord was also observed in animals treated with ATRA. CONCLUSIONS: A clear relationship between the oral administration of ATRA and an enhancement of the nociceptive withdrawal reflexes was observed in rats. This relationship was associated with an increment of the expression of the COX-2 enzyme.

Retinoids as a potential treatment for experimental puromycin-induced nephrosis.

1 Puromycin aminonucleoside (PAN)-induced nephrosis is a model of human minimal change disease. In rats, PAN induces nephrotic-range proteinuria, renal epithelial cell (podocyte) damage, infiltration of mononuclear leukocytes, and apoptosis of several renal cell types. 2 Retinoic acid (RA) modulates a wide range of biological processes, such as inflammation and apoptosis. Since renal damage by PAN is characterized by inflammatory infiltration and epithelial cell death, the effect of treatment with all-trans RA (tRA) was examined in the PAN nephrosis model and in the cultured differentiated podocyte. 3 Treatment with tRA 4 days after PAN injection did not inhibit the proteinuria peak but reversed it significantly. However, treatment with tRA both before and 2 days after the injection of PAN protected the glomerular epithelial cells, diminishing the cellular edema and diffuseness of the foot process effacement. Preservation of the podocyte architecture correlated with the inhibition of proteinuria. The anti-inflammatory effect of tRA was evidenced by the inhibition of PAN-induced interstitial mononuclear cell infiltration and the decreased renal expression of two molecules involved in monocyte infiltration: fibronectin and monocyte chemoattractant protein-1. TUNEL assays showed that tRA inhibited the PAN-induced apoptosis of cultured differentiated mouse podocytes. 4 We conclude that tRA treatment may prevent proteinuria by protecting the podocytes from injury and diminishing the interstitial mononuclear infiltrate in the model of PAN nephrosis. Retinoids are a potential new treatment for kidney diseases characterized by proteinuria and mononuclear cell infiltration.