SFEBES2016 Poster Presentations Neoplasia, cancer and late effects (18 abstracts)
The prolactin receptor variant, Asn492Ile, results in activation of the Akt signalling pathway, and is found more frequently in patients with prolactinomas
Caroline Gorvin 1 , Paul Newey 1, , Victoria Stokes 1 , Angela Rogers 1 , Georgia Ntali 1 , Peter Lees 3 , Niki Karavitaki 4, , Ashley Grossman 4 & Rajesh Thakker 1
1University of Oxford, Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Oxford, UK; 2Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, Dundee, UK; 3Faculty of Medical Leadership and Management, London, UK; 4Department of Endocrinology, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, UK; 5University of Birmingham, Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, Birmingham, UK.
The prolactin receptor (PRLR) is a type-I cytokine receptor that plays critical roles in mammary gland development, lactation and glucose metabolism, and PRLR mutations have been associated with breast cancer and familial hyperprolactinaemia. The PRLR signals via Janus kinase-2-signal transducer and activator of transcription-5 (JAK2-STAT5) or phosphoinositide 3-kinase-Akt (PI3K-Akt) pathways to mediate changes in transcription, differentiation and proliferation, and we hypothesised that some PRLR variants may be associated with the occurrence of prolactinomas. We investigated leukocyte DNA from 46 patients (25 males and 21 females, mean age at diagnosis=37.5 years) with prolactinomas, of which ~65% were macroadenomas. The PRLR Ile492 variant (wild-type Asn492) occurred more frequently in prolactinoma patients than normals in the exome variant server data from >6,500 individuals (19.57% versus 0.24%, P<0.0001). The effects of the PRLR WT Asn492 and variant Ile492 were assessed by transient transfection of WT and variant PRLR constructs in HEK293 cells that were treated with prolactin (0–1,000 ng/ml). Immediate signalling events were measured using phospho-STAT5 (pSTAT5) and phospho-Akt (pAkt) AlphaScreen assays, and later signalling events were assessed using a STAT5-dependent gene expression assay, utilising a cytokine inducible SH2-containing protein (CISH) luciferase reporter, and a CellTiter Blue proliferation assay. The prolactin-induced pSTAT5 and CISH luciferase reporter activity were similar in cells expressing PRLR Asn492 and Ile492, thereby demonstrating that Ile492 has no effect on JAK2-STAT5 signalling. However, pAkt signalling was significantly increased by >65% (P<0.02), and proliferation at 48, 72 and 96 h, by 123.96±60.06%, 194.75±83.18% and 102.91±27.43%, P<0.02, respectively) in Ile492 expressing cells compared to wild-type (Asn492) expressing cells. Thus, the Ile492 PRLR variant, which increased Akt signalling and cell proliferation, occurs more frequently in patients with prolactinomas, thereby indicating that PRLR variants may contribute to pathogenicity by multiple signalling mechanisms.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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