Insulin-like growth factor regulation of mammary gland development and tumorigenesis

Excerpt

Insulin-like growth factors (IGFs) are potent mitogens and survival factors. In the mammary gland, IGFs stimulate proliferation, differentiation, and survival during numerous developmental stages; IGF signaling is required for puberty-dependent ductal outgrowth, stimulates lobuloalveolar development during pregnancy, and is reduced or absent during apoptosis-driven involution. Much of our knowledge of IGF action in the mammary gland in vivo comes from knockout or transgenic models. However, very few of these studies have examined the consequence of these gene alterations on IGF signaling in vivo. We have recently shown that intravenous injection of IGF-I stimulates IGF-IR and IRS phosphorylation in the mammary gland, and we are currently assessing the effect of targeted gene deletion of overexpression of IGF signaling components on downstream signaling in the mammary gland in vivo. …