Quantitative in-situ hybridization histochemistry of anterior pituitary hormone mRNA species in human pituitary adenomas

We have examined the anterior pituitary hormone messenger (m) RNA species contained in biopsies of 41 pituitary tumours obtained at hypophysectomy using in-situ hybridization histochemistry. The adenoma were grouped clinically into 12 prolactinomas, 8 somatotrope adenomas, 16 non-functioning, 4 Nelson's syndrome, and 1 thyrotrope adenoma. Of these, 10 contained no detectable anterior pituitary hormone mRNA species and 11 appeared to be expressing the gene responsible for the patients' clinical state in isolation. In a number of cases the accumulation of specific mRNA species was not accompanied by an increase in the circulating levels of the corresponding hormone or subunit. Evidence of activation of more than 1 anterior pituitary hormone gene was present in 16 adenomas of which only 7 showed a pattern of activation or amplification of gene expression which would suggest deregulation of either the inositol phospholipid or cAMP second messenger pathway. It was therefore not possible from these data to postulate that isolated deregulation of a single second messenger transduction pathway is a common etiological factor in pituitary tumour formation.