Induction of osteopontin gene expression during mammary gland involution and effects of glucocorticoid on its expression in mammary epithelial cells

To understand the molecular mechanisms of mammary gland involution, an invo lution-induced clone was identified from a cDNA library of mouse mammary gl and by differential screening. Characterization of a clone by sequencing an d northern analysis showed that expression of the osteopontin gene was indu ced during involution of mouse mammary gland. But induction of the osteopon tin gene was not observed in apoptotic HC11 mammary epithelial cells under serum starvation. In HCII cells, dexamethasone treatment from the seeding s tage showed five-fold induction of osteopontin gene expression, but the exp ression was not changed when dexamethasone was added to confluent cells.