CSF nerve growth factor (β-NGF) is increased but CSF insulin-like growth factor-(IGF-1) is normal in children with tuberous sclerosis and infantile spasms.
Our results show that an EGF independent pathway is more important than that involving IGF-I for growth and survival of TSC(-/-) ASM cells, and such EGF-dependency is the result of the lack of tuberin.
Insulin-like growth factor-I plays a key role in this balance by activating the Akt/tuberous sclerosis complex 2/mammalian target of rapamycin pathway.
The autocrine release of IGF-1 may therefore be a powerful mechanism of survival of the tightly packed cells in the thick-walled vessels of TSC angiomyolipoma and in lymphangioleiomyomatosis (LAM) nodules.