pmg‐1, a novel gene specifically expressed during the invasive growth phase of the mammary gland at puberty

The acquisition of invasive properties is a crucial event during carcinogenesis, determining the clinical outcome. The mammary gland at puberty provides an ideal model for investigating the induction and control of invasive growth. During this growth phase, the mammary epithelium participates in a normal, hormonally controlled invasive penetration into the stroma. We have applied the differential display method to search for genes specifically activated during this developmental stage. We have identified and molecularly characterized a novel pubertal mammary gland specific gene, pmg-1. This gene is conserved in mammals and encodes a protein of 19.9 kDa. Northern blotting and in situ hybridization revealed that pmg-1 expression was exquisitely restricted to the epithelium at early puberty. To our knowledge this represents the first isolation of a gene specifically associated with the induction of mammary epithelial invasiveness at puberty.