In recent years, the activation of the insulin-like growth factor (IGF) system in @entity5 has emerged as a key factor for @entity5 progression and resistance to apoptosis. Therefore, a variety of strategies have been developed to block the type I IGF receptor ( @entity442 -R), which is thought to mediate the biological effects of both @entity442 and @entity5100 . However, recent data suggest that the IGF signalling system is complex and that other receptors are involved. To unravel the complexity of the IGF system in @entity259 , @entity442 and @entity5100 production, and the expression and function of their cognate receptors were studied. Both IGFs were found to be locally produced in @entity259 : @entity442 by stromal cells and @entity5100 by malignant thyrocytes. Values were significantly higher in malignant tissue than in normal tissue. @entity442 -Rs were overexpressed in differentiated @entity1377 but not in poorly differentiated or undifferentiated @entity5 , whereas insulin receptors (IRs) were greatly overexpressed in all @entity5 hystotypes, with a trend for higher values in dedifferentiated @entity5 . As a consequence of IR overexpression, high amounts of @entity442 -R hybrids (which bind @entity442 with high affinity) were present in all @entity259 histotypes. Because of recent evidence that isoform A of IR (IR-A) is a physiological receptor for @entity5100 in fetal life, the relative abundance of IR-A in @entity259 was measured. Preliminary data indicate that overexpressed IRs mainly occur as IR-A in @entity259 . These data indicate that both IR/ @entity442 -R hybrids and IR-A play an important role in the overactivation of the IGF system in @entity259 and in @entity442 mitogenic signalling in these @entity5 . J Clin PATHOL: Mol Pathol

The IGF system in XXXX : new concepts.

@entity1377 :: ('MESH:D002291', 'Disease') :: ['papillary carcinomas'] @entity5 :: ('MESH:D009369', 'Disease') :: ['cancer', 'tumours', 'tumour'] @entity442 :: ('3479', 'Gene') :: ['IR/IGF-I', 'IGF-I'] @entity5100 :: ('3481', 'Gene') :: ['IGF-II'] @entity259 :: ('MESH:D013964', 'Disease') :: ['thyroid cancer']
@entity259 :: (MESH:D013964,Disease) :: ['thyroid cancer']
