RESUMO
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.
Assuntos
Aromatase/genética , Proteína 1 de Resposta de Crescimento Precoce/genética , Flavonas/farmacologia , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo , Aromatase/metabolismo , Produtos Biológicos/farmacologia , Células Cultivadas , Ensaios de Seleção de Medicamentos Antitumorais , Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Feminino , Flavonas/química , Inativação Gênica , Humanos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Células MCF-7 , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
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.
Assuntos
Neoplasias da Mama/metabolismo , Proteína 1 de Resposta de Crescimento Precoce/fisiologia , Leptina/fisiologia , Sítios de Ligação , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Proteína 1 de Resposta de Crescimento Precoce/genética , Feminino , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Leptina/genética , Sistema de Sinalização das MAP Quinases/genética , Sistema de Sinalização das MAP Quinases/fisiologia , Regiões Promotoras Genéticas/efeitos dos fármacos , Regiões Promotoras Genéticas/genética , RNA Mensageiro/metabolismo , Fatores de Transcrição/genética , Transcrição Gênica/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacos , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/fisiologiaRESUMO
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].
Assuntos
Neoplasias da Mama/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Leptina/farmacologia , Fator de Transcrição AP-1/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Progressão da Doença , Feminino , Humanos , Fator de Crescimento Insulin-Like I/biossíntese , Fator de Crescimento Insulin-Like I/genética , Leptina/metabolismo , Células MCF-7 , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-fos/metabolismo , Proteínas Proto-Oncogênicas c-jun/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fator de Transcrição AP-1/genética , Ativação Transcricional/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
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.