RESUMEN
OBJECTIVE AND DESIGN: The proinflammatory cytokine tumor necrosis factor alpha (TNF-α) has an inhibitory role in gonadal functions particularly in the steroidogenesis of Leydig cells. A detailed understanding of the mechanisms by which TNF-α regulates testicular steroidogenesis will be helpful in the design of novel clinical interventions for the treatment and prevention of male reproductive disorders. Here, we report that TNF-α-mediated activation of DAX-1 (dosage-sensitive sex reversal adrenal hypoplasia congenital critical region on X chromosome, gene 1) is involved in the inhibition of Leydig cell steroidogenesis. MATERIALS AND METHODS: Rat testis Leydig tumor cells (LC-540) were treated with TNF-α (10 ng/ml) for different time intervals. To elucidate the pathways of intracellular signal transduction that regulate DAX-1 expression, we utilized specific inhibitors. The siRNA transfection of DAX-1 into LC-540 cells was performed by electroporation. The mRNA and protein levels were determined by RT-PCR and Western blotting, respectively. RESULTS: We found that the mRNA and protein levels of DAX-1 were increased by threefold approximately in TNF-α-treated cells when compared to controls. Staurosporine, JNK inhibitor SP600125 and ERK inhibitor PD98059 significantly decreased DAX-1 expression in TNF-α-treated Leydig cells when compared to their respective controls. Further, a siRNA-mediated knockdown of DAX-1 restores the expression of steroidogenic proteins in TNF-α-treated Leydig cells. CONCLUSIONS: These findings provide valuable information that TNF-α activates DAX-1 through JNK/ERK MAP kinase pathway which regulates the expression of steroidogenic enzyme genes in Leydig cells.
Asunto(s)
Receptor Nuclear Huérfano DAX-1/efectos de los fármacos , Receptor Nuclear Huérfano DAX-1/genética , Células Intersticiales del Testículo/efectos de los fármacos , Células Intersticiales del Testículo/metabolismo , Esteroides/biosíntesis , Factor de Necrosis Tumoral alfa/farmacología , Animales , Línea Celular , Técnicas de Silenciamiento del Gen , MAP Quinasa Quinasa 4/genética , MAP Quinasa Quinasa 4/metabolismo , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/genética , Masculino , Fosforilación , ARN Mensajero/biosíntesis , ARN Mensajero/genética , ARN Interferente Pequeño/genética , Ratas , Transducción de Señal/efectos de los fármacos , Testículo/citología , Testículo/efectos de los fármacos , Testículo/metabolismoRESUMEN
ET-743 (trabectedin; Yondelis) is approved in Europe for the treatment of soft tissue sarcomas. Emerging phase 1 and 2 clinical data have shown high response rates in myxoid liposarcoma in part owing to the inhibition of the FUS-CHOP transcription factor. In this report, we show that modulation of specific oncogenic transcription factors by ET-743 may extend to other tumor types. We demonstrate that, among a panel of pediatric sarcomas, Ewing sarcoma family of tumors (ESFTs) cell lines bearing the EWS-FLI1 transcription factor are the most sensitive to treatment with ET-743 compared with osteosarcoma, rhabdomyosarcoma, and synovial sarcoma. We show that ET-743 reverses a gene signature of induced downstream targets of EWS-FLI1 in two different ESFT cell lines (P = .001). In addition, ET-743 directly suppresses the promoter activity of a known EWS-FLI1 downstream target NR0B1 luciferase reporter construct without changing the activity of a constitutively active control in ESFT cells. Furthermore, the effect is specific to EWS-FLI1, as forced expression of EWS-FLI1 in a cell type that normally lacks this fusion protein, HT1080 cells, induces the same NR0B1 promoter, but this activation is completely blocked by ET-743 treatment. Finally, we used gene set enrichment analysis to confirm that other mechanisms of ET-743 are active in ESFT cells. These results suggest a particular role for ET-743 in the treatment of translocation-positive tumors. In addition, the modulation of EWS-FLI1 makes it a novel targeting agent for ESFT and suggests that further development of this compound for the treatment of ESFT is warranted.