Prolactin (PRL) Reagent – Jaj International

Primary hyperparathyroidism (PHPT) is an endocrine disorder most commonly affecting women, suggesting a role for female hormones and/or their receptors in parathyroid adenomas. We here investigated the prolactin receptor (PRLr) which is associated with tumor’s of the breast and other organs. PRLr expression was investigated in a panel of 37 patients with sporadic parathyroid tumor’s and its functionality in cultured parathyroid tumors cells. In comparison with other tissues and breast cancer cells, high levels of prolactin receptor gene (PRLR) transcripts were demonstrated in parathyroid tissues. PRLr products of 60/70 kDa were highly expressed in all parathyroid tumor’s.

In addition varying levels of the 80 kDa PRLr isoform, with known proliferative activity, were demonstrated. In parathyroid tumors, PRLr immunoreactivity was observed in the cytoplasm (in all cases, n = 36), cytoplasmic granule (n = 16), the plasma membrane (n = 12) or enlarged lysosomes (n = 4). In normal parathyroid rim (n = 28), PRLr was uniformly expressed in the cytoplasm and granule. In in vitro studies of short-term cultured human parathyroid tumour cells, prolactin stimulation was associated with significant transcriptional changes in JAK/STAT, RIG-I like receptor and type II interferon signaling pathways as documented by gene expression profiling. Moreover, PRLR gene expression in parathyroid tumors was inversely correlated with the patients’ plasma calcium levels.

We demonstrate that the prolactin receptor is highly abundant in human parathyroid tissues and that PRLr isoforms expression and PRLr subcellular localization are altered in parathyroid tumors. Responsiveness of PRLr to physiological levels of prolactin was observed in the form of increased PTH secretion and altered gene transcription with significant increase of RIG-I like receptor, JAK-STAT and Type II interferon signaling pathways. These data suggest a role of the prolactin receptor in parathyroid adenomas.