Proteomics and transcriptomics analyses of secretagogin down-regulation in human non-functional pituitary adenomas.

In order to explore the presence of, and the potential role of, secretagogin in human pituitary adenomas, an analytical strategy that integrated comparative proteomics and comparative transcriptomics was used to detect the protein and the mRNA expression, respectively, of secretagogin in human non-functional pituitary adenomas compared to controls. Proteomics methods included two-dimensional gel electrophoresis, 2D gel image analysis, mass spectrometry [matrix-assisted laser desorption/ionization-time of flight-peptide mass fingerprinting (MALDI-TOF PMF) and liquid chromatography-electrospray ionization-quadrupole-ion trap tandem mass spectrometry (LC-ESI-Q-IT MS/MS)], and database analysis. Transcriptomics methods included the GeneChip microarray, image processing, and data analysis. The proteomics and transcriptomics data demonstrated that secretagogin was significantly down-regulated at the protein and mRNA levels, respectively, in the human non-functional (NF) pituitary adenomas (NF-, LH+, FSH+, and FSH+ + LH+). For the secretagogin protein, the expression level was NF- < FSH+ + LH+ < FSH+ < LH+ < Control, with a range of down-regulation of 2.2-6.9 fold in non-functional pituitary adenomas compared to controls, with a significant difference (p < 0.001). For secretagogin mRNA, the expression level was NF- < LH+ < FSH+ + LH+ < FSH+ < Control, with a range of down-regulation of 1.8-18.6 fold in non-functional pituitary adenomas compared to controls that was significant (p < 0.05). The secretagogin protein expression correlated significantly with its mRNA expression. Those results suggest that secretagogin might play a role in human non-functional pituitary adenomas. This novel finding may provide clues to clarify the basic molecular mechanisms of pituitary adenoma formation, and to identify new tumor-related markers.