Aryl Hydrocarbon Receptor Regulates Cell Cycle Progression in Human Breast Cancer Cells via a Functional Interaction with Cyclin-Dependent Kinase 4

• Published in: Molecular pharmacology 2010-02, Vol.77 (2), p.195-201
• Main Authors: Barhoover, Melissa A., Hall, Julie M., Greenlee, William F., Thomas, Russell S.
• Format: Article
• Language: English
• Subjects: 17-β-estradiol; 2,3,7,8-tetrachlorodibenzo-p-dioxin; 90-kDa heat shock protein; AHR; ARNT; aryl hydrocarbon nuclear translocator; aryl hydrocarbon receptor; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; C/D FBS; CCND1; CDK4; Cell Cycle - drug effects; Cell Cycle - physiology; Cell Line, Tumor; charcoal-stripped fetal bovine serum; cyclin D1; cyclin-dependent kinase 4; Cyclin-Dependent Kinase 4 - physiology; dimethyl sulfoxide; DMEM; DMSO; Dulbecco’s modified Eagle’s medium; ECL; enhanced chemiluminescence; ER; estrogen receptor negative; estrogen receptor positive; FBS; Female; fetal bovine serum; HSP90; Humans; immunoprecipitation; MEM; minimal essential medium; PAGE; PCR; polyacrylamide gel electrophoresis; Polychlorinated Dibenzodioxins - pharmacology; polymerase chain reaction; polyvinylidene difluoride; Protein Binding - drug effects; Protein Binding - physiology; PVDF; RB1; Receptors, Aryl Hydrocarbon - physiology; retinoblastoma protein; TCDD
• ISSN: 0026-895X; 1521-0111
• DOI: 10.1124/mol.109.059675

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor with constitutive activities and those induced by xenobiotic ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). One unexplained cellular role for the AHR is its ability to promote cell cycle progression in the absence of exogenous ligands, whereas treatment with exogenous ligands induces cell cycle arrest. Within the cell cycle, progression from G1 to S phase is controlled by sequential phosphorylation of the retinoblastoma protein (RB1) by cyclin D–cyclin-dependent kinase (CDK) 4/6 complexes. In this study, the functional interactions between the AHR, CDK4, and cyclin D1 (CCND1) were investigated as a potential mechanism for the cell cycle regulation by the AHR. Time course cell cycle and molecular experiments were performed in human breast cancer cells. The results demonstrated that the AHR and CDK4 interact within the cell cycle, and the interaction was disrupted upon TCDD treatment. The disruption was temporally correlated with G1 cell cycle arrest and decreased phosphorylation of RB1. Biochemical reconstitution assays using in vitro-translated protein recapitulated the AHR and CDK4 interaction and showed that CCND1 was also part of the complex. In vitro assays for CDK4 kinase activity demonstrated that RB1 phosphorylation by the AHR/CDK4/CCND1 complex was reduced in the presence of TCDD. The results suggest that the AHR interacts in a complex with CDK4 and CCND1 in the absence of exogenous ligands to facilitate cell cycle progression. This interaction is disrupted by exogenous ligands, such as TCDD, to induce G1 cell cycle arrest.