Molecular classification of pituitary adenomas: in search for criteria useful for high-throughput studies

The mechanism of pathogenesis of pituitary adenomas is still unknown, and it shows differences in pituitary cells of different origin. The aim of our study was to analyse the gene expression profile of pituitary hormones and their precursor genes: PRL, GH, POMC, TSHb, LHb, FSHb, and CGA by QPCR in particular types of pituitary adenomas, and to evaluate the results in the context of sample selection for microarray studies.

Analysis of the gene expression profile was performed in 84 samples of pituitary adenomas, by real-time quantitative PCR (QPCR).

As expected, expression of GH gene was significantly higher in somatotropinomas than in prolactinomas (p < 0.05). For POMC gene we noticed lower expression in all pituitary adenomas, except adrenocorticotropinomas (p < 0.05). In the case of PRL gene, the highest expression was observed; PRL+ adenomas were in third place. LHb and FSHb genes showed the highest expression, respectively, in LH-producing and FSH-producing pituitary adenomas; however, our analysis did not show statistically significant differences between LH-producing and FSH-producing adenomas.

Our study showed that GH is a characteristic gene for somatotropinomas. We drew a similar conclusion for POMC gene and adrenocorticotropinomas. However, the results that we obtained for PRL, TSHb, LHb, FSHb, and CGA genes indicate that evaluation of gene expression is not sufficient for classification of particular subtypes of pituitary adenomas.