Transcripts of PTTG and Growth Factors bFGF and IGF-1 are Correlated in Pituitary Adenomas

The reasons for the increase of pituitary tumor-transforming gene (PTTG) transcripts in about 90 % of pituitary adenomas are still not fully understood, although upregulation by basic fibroblast growth factor (bFGF) has been discussed as a potential cause. A possible influence of the Insulin like Growth Factor 1 (IGF-1) might be of interest, since this protein is also synthesized in most pituitary adenomas. Moreover, the principal regulation of the PTTG gene by IGF-1 and Insulin has been demonstrated in astrocytoma and breast cancer cells. We analyzed a large group (103 patients) of unselected clinical pituitary adenoma samples. From total RNA of frozen tumor samples (all subtypes) cDNA (complementary DNA) was synthesized and transcripts of PTTG, bFGF, IGF-1 were measured by Real-Time-PCR. Not only mRNA (messenger RNA) levels of bFGF, but also of IGF-1, correlated strongly with PTTG transcripts. This result was obtained, when all pituitary adenoma samples were included in the statistical calculations, irrespective of their subclassification. Our study suggests a connection between PTTG and IGF-1 in pituitary adenomas.