Gland size is associated with changes in gene expression profiles in sporadic parathyroid adenomas

Sporadic parathyroid adenomas (SPAs) are benign neoplasms responsible for most cases of primary hyperparathyroidism (pHPT). The molecular pathways responsible for the variations in clinical severity of pHPT are unknown. We studied gene expression profiles in patients with SPAs and pHPT to determine associations between these changes and clinical parameters.

We selected 10 patients with solitary SPAs and nonfamilial, non-MEN1 pHPT treated with surgery from 2001 to 2003. Pathologic and clinical data were reviewed. At operation, tissues from SPAs were frozen in liquid nitrogen; total RNA was obtained from sections, and the diagnosis was confirmed with hematoxylin and eosin staining. Control normal parathyroid RNA was age- and sex-matched. RNA was amplified, labeled, and hybridized to a microarray of 22,272 human oligonucleotides. Cluster analysis of gene expression, analysis of expression ratios, and comparison of clinical parameters were performed.

All patients were cured; all specimens were consistent with SPAs. K means clustering divided the 10 patients into 2 distinct 5-patient gene expression groups by using uncentered correlation based on gene subgrouping. Of the clinical parameters, only the mean gland volume was significantly different between group 1 (390 +/- 160 mm(3)) and group 2 (1080 +/- 615 mm(3); P = .032 by Mann-Whitney test). Seventy-five genes were significantly upregulated or downregulated (with a ratio of <.33 or >3) compared with controls. These genes included the v-fos viral oncogene homolog and six calcium ion-binding signaling proteins.

Differential expression of a few critical genes may contribute to differences in gland volume in SPAs. A better understanding of these pathways may help to define the pathophysiology of pHPT.