Hormonal regulation of insulin-like growth factor II and insulin-like growth factor binding protein expression by XXXX cells in vivo: evidence for stromal epithelial interactions.

@entity2620 @entity7045 @entity7815 @entity0 @entity5 @entity10777 @entity10778 @entity35 @entity9929 @entity2619
Insulin-like growth factors (IGFs) I and II are potent mitogens for @entity0 cells. Their proliferative activity is likely to be influenced by their binding proteins (IGFBPs), a family of newly identified proteins. We report here on the in vivo hormonal regulation of mRNAs for @entity2620 and IGFBPs in the @entity7045 -induced @entity35 @entity5 , a well-established model of hormone-responsive mammary @entity5 . @entity2620 mRNA levels tended to decrease in regressing @entity5 following ovariectomy, and they markedly increased upon reactivation of @entity5 growth with hormone repletion. Ovariectomy induced a drastic increase in @entity2619 mRNA which was reversible with hormone repletion. Similar but more modest changes were observed with @entity7815 mRNA. In contrast, @entity9929 and @entity10777 mRNAs tended to decrease with ovariectomy and increase with hormone repletion. These latter effects, however, were modest, variable, and not statistically significant. In situ hybridization analysis revealed that @entity2620 , @entity10778 , and @entity2619 mRNAs were localized in the stromal component of the @entity5 , whereas @entity7815 mRNA was expressed by epithelial cells. We conclude that hormonal regulation of IGFBP expression is heterogeneous, thus suggesting divergent biological functions for these peptides. Our data also emphasize the importance of potential stromal-epithelial interactions in the control of @entity0 cell proliferation by IGFs.
