Background: IGF-1 is a ubiquitous growth factor that has been shown to play an important role in breast tissue development and tumorigenesis. Previously we have shown that IGF-1 expression is lost in approximately 1/3 of breast carcinomas. It is unsure whether this indicates the existence of a subset of breast cancers that may behave differently clinically and on a molecular level. Aims: To assess and quantify the mRNA expression of (i) Cox-2 and c-myc, genes implicated in breast tumourgenesis, and (ii) GH, GH receptor, IGF-1R and IGFBP-3, in the two groups (IGF-1 positive and IGF-1 negative) of breast carcinoma. Methods: Total RNA was extracted from samples of 32 breast cancers, of which 13 had absent IGF-1 expression. Using a real-time, hydrolysis probe dependent RT-PCR assay ('Taqman'), transcription was quantified and expressed as copy number/µg total RNA. Results: Expression of both c-myc and Cox-2 was significantly higher in the IGF-1 positive tumours. In addition the expression of GHR and IGFBP-3 was also increased in the IGF-1 positive breast cancer group. There was no difference in GH or IGF-1R expression between groups.
Conclusions: There are two distinct groups of breast carcinoma, with respect to IGF-1 expression. The reduced expression of c-myc and cox-2 in the IGF-1 negative group suggests a lower level of proliferation and angiogenesis. However the clinical significance of these differences remains to be determined.
03 - 04 Dec 2001
Society for Endocrinology