A woman's susceptibility to breast cancer is influenced by the timing of normal developmental events, such as her first full-term pregnancy, suggesting that the effects of oncogene activation might be modulated by the developmental state of the breast. On p. 1147, Blakely and colleagues provide in vivo molecular evidence for this hypothesis by showing a developmental stage-specific effect of aberrant MYC activation in the mouse mammary gland. The researchers use a doxycycline-inducible transgenic mouse model to show that MYC overexpression during a specific 72-hour window in mid-pregnancy inhibits post-partum lactation. Unexpectedly, MYC overexpression does this by inducing precocious lactation via Stat5 activation; the absence of a suckling stimulus then causes the gland to involute prematurely to a non-lactating state. The researchers conclude that the oncogenic effects of MYC may similarly depend on the developmental stage of the mammary gland when the oncogene is activated.

©2005.
2005