RESUMEN
Estrogen overproduction is closely associated with the development of estrogen receptor-positive breast cancer. Aromatase, encoded by the cytochrome P450 19 (CYP19) gene, regulates estrogen biosynthesis. This study aimed to identify active flavones that inhibit CYP19 expression and to explore the underlying mechanisms. CYP19 expression was evaluated using reverse transcription PCR, quantitative real-time PCR, and immunoblot analysis. The role of transcription factor early growth response gene 1 (EGR-1) in CYP19 expression was assessed using the short-hairpin RNA (shRNA)-mediated knockdown of EGR-1 expression in estrogen receptor-positive MCF-7 breast cancer cells. We screened 39 flavonoids containing 26 flavones and 13 flavanones using the EGR1 promoter reporter activity assay and observed that chrysoeriol exerted the highest inhibitory activity on tumor necrosis factor alpha (TNFα)-induced EGR-1 expression. We further characterized and demonstrated that chrysoeriol inhibits TNFα-induced CYP19 expression through inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2)-mediated EGR-1 expression. Chrysoeriol may be beneficial as a dietary supplement for the prevention of estrogen receptor-positive breast cancer, or as a chemotherapeutic adjuvant in the treatment of this condition.
Asunto(s)
Aromatasa/genética , Proteína 1 de la Respuesta de Crecimiento Precoz/genética , Flavonas/farmacología , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Factor de Necrosis Tumoral alfa/metabolismo , Aromatasa/metabolismo , Productos Biológicos/farmacología , Células Cultivadas , Ensayos de Selección de Medicamentos Antitumorales , Proteína 1 de la Respuesta de Crecimiento Precoz/metabolismo , Femenino , Flavonas/química , Silenciador del Gen , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Células MCF-7 , Factor de Necrosis Tumoral alfa/farmacologíaRESUMEN
Leptin is a cytokine that regulates energy metabolism. Leptin can promote breast cancer progression in obese women. However, the mechanism of regulation of leptin expression in breast cancer cells is unclear. Tumor necrosis factor-alpha (TNF-α) stimulated the transcription of the leptin gene. Using mutant promoter constructs, we demonstrated that the EGR1-binding motif in the proximal region of the leptin gene is required for leptin transcription by TNF-α. Forced expression of EGR1 stimulated leptin promoter activity, whereas silencing of EGR1 by RNA interference reduced TNF-α-induced leptin protein accumulation. The ERK1/2 pathway contributed to the expression of EGR1 and leptin by TNF-α. Our results suggest that EGR1 targets the leptin gene in response to TNF-α stimulation in breast cancer cells.
Asunto(s)
Neoplasias de la Mama/metabolismo , Proteína 1 de la Respuesta de Crecimiento Precoz/fisiología , Leptina/fisiología , Sitios de Unión , Neoplasias de la Mama/genética , Línea Celular Tumoral , Proteínas de Unión al ADN/genética , Proteína 1 de la Respuesta de Crecimiento Precoz/genética , Femenino , Regulación Neoplásica de la Expresión Génica/genética , Humanos , Leptina/genética , Sistema de Señalización de MAP Quinasas/genética , Sistema de Señalización de MAP Quinasas/fisiología , Regiones Promotoras Genéticas/efectos de los fármacos , Regiones Promotoras Genéticas/genética , ARN Mensajero/metabolismo , Factores de Transcripción/genética , Transcripción Genética/efectos de los fármacos , Activación Transcripcional/efectos de los fármacos , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/fisiologíaRESUMEN
Leptin, an adipokine regulating energy metabolism, appears to be associated with breast cancer progression. Insulin-like growth factor-1 (IGF-1) mediates the pathogenesis of breast cancer. The regulation of IGF-1 expression by leptin in breast cancer cells is unclear. Here, we found that leptin upregulates IGF-1 expression at the transcriptional level in breast cancer cells. Activating protein-1 (AP-1)-binding element within the proximal region of IGF-1 was necessary for leptin-induced IGF-1 promoter activation. Forced expression of AP-1 components, c-FOS or c-JUN, enhanced leptin-induced IGF-1 expression, while knockdown of c-FOS or c-JUN abrogated leptin responsiveness. All three MAPKs (ERK1/2, JNK1/2, and p38 MAPK) mediated leptin-induced IGF-1 expression. These results suggest that leptin contributes to breast cancer progression through the transcriptional upregulation of leptin via the MAPK pathway. [BMB Reports 2019; 52(6): 385-390].
Asunto(s)
Neoplasias de la Mama/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Leptina/farmacología , Factor de Transcripción AP-1/metabolismo , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Línea Celular Tumoral , Progresión de la Enfermedad , Femenino , Humanos , Factor I del Crecimiento Similar a la Insulina/biosíntesis , Factor I del Crecimiento Similar a la Insulina/genética , Leptina/metabolismo , Células MCF-7 , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas c-fos/metabolismo , Proteínas Proto-Oncogénicas c-jun/metabolismo , Transducción de Señal/efectos de los fármacos , Factor de Transcripción AP-1/genética , Activación Transcripcional/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
BACKGROUND: Inflammation in the central nervous system is closely associated with pathological neurodegenerative diseases as well as psychiatric disorders. Prolonged activation of microglia can produce many inflammatory mediators, which may result in pathological neurotoxic side effects. Interleukin (IL)-6 serves as a hallmark of the injured brain. OBJECTIVE: Whole grains are known to contain many bioactive components. However, little information is available about anti-neuroinflammatory effects of grains in the CNS. This study aims to investigate the effect of Hordeum vulgare ethanol extract (HVE) on the suppression of IL-6 expression in BV2 microglia. METHODS: Inhibitory effects of HVE on IL-6 expression were analyzed by immunoblot anaysis, immunofluoresce microscopic analysis, reverse transcription-polymerase chain reaction, and luciferase promoter reporter assay. RESULTS: HVE inhibited TNFα-induced phosphorylation of IKKα/ß, IκB, and p65/RelA NF-κB. TNFα-induced IL-6 mRNA expression and promoter activity were reduced by HVE. Point mutation of NF-κB-binding site within the IL-6 gene promoter abolished TNFα-induced reporter activity, whereas exogenous expression of p65 NF-κB enhanced IL-6 promoter activity. CONCLUSION: NF-κB-binding site within the IL-6 promoter region is a HVE target element involved in the inhibition of TNFα-induced IL-6 gene transcription. HVE inhibits TNFα-induced IL-6 expression via suppression of NF-κB signaling in BV2 microglial cells.