Microarray analysis of in vivo glucocorticoid antiapoptotic action on mammary gland involution

HOIJMAN, E.; QUAGLINO, A.; KORDON, E.C.; KALKO, S.G.; PECCI, A.

Rosario, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2006

SAIB

In vivo administration of glucocorticoids (GCs) prevents the apoptosis of epithelial cells of post lactating involuting mammary gland. The aim of this work was to identify GC-regulated genes during this process by performing a genome-wide screen using oligonucleotide microarrays. The involution was induced in BALB/c mice by removing the pups. A subcutaneous injection of Dexamethasone 0.5 mg/100g body weight or vehicle, was applied at 0, 24 and 48 hours after weaning. After additional 24 hours, mammary gland # 4 were excised and total RNA prepared. Affymetrix oligonucleotide GeneChip Mouse Genome 430 2.0 array was used and RMA expression values were calculated by the AMARGE web tool. According to the limma package of Bioconductor analysis, it was found that from 34000 genes tested, 492 were differentially expressed between the two experimental groups, being 137 induced (fold changes from 1.49 to 32.8) and 355 repressed (fold changes from 0.68 to 0.12) by the GCs treatment. According to the EASE analysis of over-represented gene ontology terms, the most relevant category was “Tumor suppressor”, comprised 5 genes all down-regulated by GCs. Thus, these genes could be potential candidates as mediators of the GC antiapoptotic action observed in the mammary gland.