Molecular profiling of parathyroid hyperplasia, adenoma and carcinoma

The objective of the study was to examine proliferation and apoptosis associated gene expression in the whole sequence parathyroid lesions to reveal specific features of carcinoma. This study was based on surgically removed parathyroid tissues, gene expression analysis was performed both at gene and protein level. First, mRNA isolation was performed from deep-frozen tissue samples, and further apoptosis pathway-specific cDNA macroarray analysis was carried out. The results were validated with real-time PCR. Subsequently, protein expression was analyzed with immunhistochemistry on Tissue Micro Array multi-blocks derived from several paraffin-embedded samples. cDNA macroarrays revealed elevated expression of both pro-apoptotic (FAS receptor, TRAIL ligand, CASPASE8, and -4) and anti-apoptotic (cIAP1, APOLLON) genes in benign proliferative lesions compared to that in normal gland. TMA studies showed overexpression of KI67, P53, SURVIVIN and APOLLON protein and failure of expression of P27, BCL2, BAX, CHROMOGRANIN-A, SYNAPTOPHYSIN, CYCLIND1, FLIP, TRAIL, CK8, CK18, CK19 in parathyroid carcinoma was detected. These alterations in gene expression of the investigated products could be used in differentiation between beningn and malignant proliferative processes of the parathyroid gland. Authors conclude that a series of alterations in gene expression such as overexpression of APOLLON, P53, KI67 and suppression of P27, BCL2, BAX lead to uncontrolled cell proliferation, but still not leading to increased apoptotic activity in parathyroid carcinoma.