miR-26a regulates cell cycle in ACTH-secreting pituitary adenomas through Protein Kinase C delta

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 163-194-Pituitary Disorders & Case Reports
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-178
Erica Gentilin1, Federico Tagliati2, Daniela Molè1, Maria Rosaria Ambrosio3, Ettore Ciro degli Uberti1 and Maria Chiara Zatelli*1
1University of Ferrara, Ferrara, Italy, 2University of Ferrara, FERRARA, Italy, 3Endocrinology, University of Ferrara, Ferrara, Italy
The functional aftermath of miRNA dysregulation in ACTH-secreting pituitary adenomas has not been demonstrated. miRNAs represent diagnostic and prognostic biomarkers, as well as putative therapeutic targets; their investigation may shed light on the mechanisms that underpin pituitary adenoma development and progression. Drugs interacting with such pathways may help in achieving disease control also in the settings of ACTH-secreting pituitary adenomas. We investigated the expression of 10 miRNAs among those that were found as most dysregulated in human pituitary adenoma tissues  in the settings of a murine ACTH-secreting pituitary adenoma cell line, AtT20/D16v-F2. The selected miRNAs to be submitted to further investigation in AtT20/D16v-F2 cells represent an expression panel including 5 up-regulated and 5 down-regulated miRNAs. Among these, we selected the most dysregulated mouse miRNA and searched for miRNA targets and their biological function. We found that AtT20/D16v-F2 cells have a specific miRNAs expression profile and that miR-26a is the most dysregulated miRNA. The latter is overexpressed in human pituitary adenomas and can control viable cell number in the in vitro model without involving caspase 3/7 mediated apoptosis. We demonstrated that protein kinase C delta (PRKCD) is a direct target of miR-26a and that miR26a inhibition delays cell cycle in G1 phase. This effect involves downregulation of cyclin E and cyclin A expression and p27 and JNK phosphorylation via PRKCD modulation.

miR-26a and related pathways, such as PRKCD, play an important role in cell cycle control of ACTH pituitary cells, opening new therapeutic possibilities for the treatment of persistent/recurrent Cushing’s disease.

Nothing to Disclose: EG, FT, DM, MRA, ECD, MCZ

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