Deciphering the Dosage-dependent SF-1 Regulome in Adrenocortical Cancer Cells

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 17-28-Adrenal Tumors & Pheochromocytoma
Basic/Clinical
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-22
Enzo Lalli*1, Mabrouka Doghman1, Bonald Cavalcante Figueiredo2, Marco Volante3 and Mauro Papotti3
1IPMC CNRS, Valbonne, France, 2Instituto de Pesquisa Pelé Pequeno Principe, Curitiba PR, Brazil, 3University of Turin, Orbassano, Italy
Nuclear receptor SF-1 has an essential role in endocrine physiopathology, regulating adrenogonadal development, adrenocortical cell proliferation and tumor formation in mice in a dosage-dependent fashion. Furthermore, SF-1 overexpression is associated with a poor clinical outcome in adrenocortical cancer (ACC).

To investigate the mechanisms involved in dosage-dependent regulation of gene expression by SF-1, we have identified its sites of binding to chromatin in conditions of basal and increased dosage using chromatin immunoprecipitation coupled to high-throughput sequencing (ChIP-seq) in our H295R cell model where SF-1 overexpression can be triggered by doxycycline treatment (Doghman et al., Mol. Endocrinol. 21: 2968-2987, 2007). In conditions of basal expression, SF-1 bound to about 4000 distinct sites in chromatin. Only 17.7% of these sites are located inside or in the proximity (±10 kb) of known genes. Strikingly, in conditions of SF-1 overexpression, the number of sites bound in chromatin was nearly tripled, 32.7% of which lies in the proximity of genes. Expression profiling showed that 708 genes are upregulated ≥2-fold, while 676 genes are down-regulated ≥2-fold when SF-1 is overexpressed. A significant overlap exists between genes bound by SF-1 only when overexpressed and upregulated genes, while the correlation is not significant between genes bound by SF-1 only when overexpressed and downregulated genes. These data suggest that SF-1 has a direct activating function on genes upregulated when the factor is overexpressed, while its negative effects on gene expression are probably indirect. By motif analysis, we could find the consensus SF-1 binding sequence (CAAGGTCA) and/or its variants in bound sites. This sequence was also significantly enriched in chromatin sites bound by SF-1 in primary ACC samples. Other predicted transcription factor binding sequences were also significantly enriched in SF-1 bound DNA. Based on this data, further work is in progress to elucidate the mechanisms of regulation of gene expression by SF-1 in a dosage-dependent fashion.

Nothing to Disclose: EL, MD, BCF, MV, MP

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: This work was supported by grants from Institut National du Cancer (2008-045), Conseil Général 06, CNRS, Association pour le Recherche sur le Cancer (Projets ARC SFI20111203563) and European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n°259735 (ENS@T-CANCER) to E.L.