The prolactin receptor variant, Asn492Ile, results in activation of the Akt signalling pathway, and is found more frequently in patients with prolactinomas

Research output: Contribution to conference (unpublished)Posterpeer-review

Colleges, School and Institutes

Abstract

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 diagnosisZ37.5 years) with
prolactinomas, of which w65% were macroadenomas. The PRLR Ile492 variant
(wild-type Asn492) occurred more frequently in prolactinoma patients than
normals in the exome variant server data from O6,500 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 O65% (P!0.02), and proliferation at 48, 72 and 96 h,
by 123.96G60.06%, 194.75G83.18% and 102.91G27.43%, 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.

Details

Original languageEnglish
Publication statusPublished - Nov 2016
EventSociety for Endocrinology BES 2016 - Brighton, United Kingdom
Duration: 7 Nov 20169 Nov 2016

Conference

ConferenceSociety for Endocrinology BES 2016
CountryUnited Kingdom
CityBrighton
Period7/11/169/11/16