Basic Fibroblast Growth Factor Expression by Two Prolactin and Thyrotropin-Producing Pituitary Adenomas

We investigated the expression of basic fibroblast growth factor (bFGF) in an aggressive type of PRL and TSH-producing pituitary adenoma. Immunocytochemistry and electron microscopy were used to characterize the tumors removed from two patients. lmmunoassays were used to measure hormone and bFGF levels in vitro and in vivo. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect bFGF mRNA expression by these tumors. Morphologically, these tumors were characterized by an unusual plurihormonal pattern with expression of PRL and TSH and the ultrastructural characteristics of the silent subtype 3 adenoma; in addition, both adenomas displayed marked interstitial fibrosis. bFGF was measurable in the circulation of these patients ranging from 7.5-20.5 pg/mL (normal < 1 pg/mL). bFGF concentrations were reduced following surgical adenomectomy. bFCF in culture media was present in concentrations of 197-387 pg/24h/10(5) cells. bFGF mRNA expression was identified in both adenomas examined. bFGF levels were unaltered in the culture media and in the serum of patients following GnRH and TRH treatment. In conclusion, the expression of bFGF by these plurihormonal pituitary adenomas suggests the possibility that it may play a role in the development of fibrosis and tumor cell proliferation of this unusual type of pituitary neoplasm.