Smoke carcinogens cause bone loss through the aryl hydrocarbon receptor and induction of Cyp1 enzymes.
Proc Natl Acad Sci U S A
; 110(27): 11115-20, 2013 Jul 02.
Article
em En
| MEDLINE
| ID: mdl-23776235
ABSTRACT
Smoking is a major risk factor for osteoporosis and fracture, but the mechanism through which smoke causes bone loss remains unclear. Here, we show that the smoke toxins benzo(a)pyrene (BaP) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) interact with the aryl hydrocarbon receptor (Ahr) to induce osteoclastic bone resorption through the activation of cytochrome P450 1a/1b (Cyp1) enzymes. BaP and TCDD enhanced osteoclast formation in bone marrow cell cultures and gavage with BaP stimulated bone resorption and osteoclastogenesis in vivo. The osteoclastogenesis triggered by BaP or RANK-L was reduced in Ahr(-/-) cells, consistent with the high bone mass noted in Ahr(-/-) male mice. The receptor activator of NF-κB ligand (RANK-L) also failed to induce the expression of Cyp1 enzymes in Ahr(-/-) cells. Furthermore, the osteoclastogenesis induced by TCDD was lower in Cyp1a1/1a2(-/-) and Cyp1a1/1a2/1b1(-/-) cultures, indicating that Ahr was upstream of the Cyp enzymes. Likewise, the pharmacological inhibition of the Cyp1 enzymes with tetramethylsilane or proadifen reduced osteoclastogenesis. Finally, deletion of the Cyp1a1, Cyp1a2, and Cyp1b1 in triple knockout mice resulted in reduced bone resorption and recapitulated the high bone mass phenotype of Ahr(-/-) mice. Overall, the data identify the Ahr and Cyp1 enzymes not only in the pathophysiology of smoke-induced osteoporosis, but also as potential targets for selective modulation by new therapeutics.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fumaça
/
Reabsorção Óssea
/
Carcinógenos
/
Hidrocarboneto de Aril Hidroxilases
/
Receptores de Hidrocarboneto Arílico
Tipo de estudo:
Prognostic_studies
/
Risk_factors_studies
Limite:
Animals
/
Female
/
Humans
/
Male
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article