Expression and activity of the calcitonin receptor family in a sample of primary human high-grade gliomas

Anna Ostrovskaya,Peter J Wookey,Denise Wootten,Sebastian G B Furness,Brett W Stringer,Caroline Hick,Dana S Hutchinson,Patrick M Sexton

doi:10.1186/s12885-019-5369-y

Anna Ostrovskaya, Peter J Wookey + Show 6 more

Open Access

https://doi.org/10.1186/s12885-019-5369-y

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Abstract

BackgroundGlioblastoma (GBM) is the most common and aggressive type of primary brain cancer. With median survival of less than 15 months, identification and validation of new GBM therapeutic targets is of critical importance.ResultsIn this study we tested expression and performed pharmacological characterization of the calcitonin receptor (CTR) as well as other members of the calcitonin family of receptors in high-grade glioma (HGG) cell lines derived from individual patient tumours, cultured in defined conditions.Previous immunohistochemical data demonstrated CTR expression in GBM biopsies and we were able to confirm CALCR (gene encoding CTR) expression. However, as assessed by cAMP accumulation assay, only one of the studied cell lines expressed functional CTR, while the other cell lines have functional CGRP (CLR/RAMP1) receptors. The only CTR-expressing cell line (SB2b) showed modest coupling to the cAMP pathway and no activation of other known CTR signaling pathways, including ERK1/2 and p38 MAP kinases, and Ca2+ mobilization, supportive of low cell surface receptor expression.Exome sequencing data failed to account for the discrepancy between functional data and expression on the cell lines that do not respond to calcitonin(s) with no deleterious non-synonymous polymorphisms detected, suggesting that other factors may be at play, such as alternative splicing or rapid constitutive receptor internalisation.ConclusionsThis study shows that GPCR signaling can display significant variation depending on cellular system used, and effects seen in model recombinant cell lines or tumour cell lines are not always reproduced in a more physiologically relevant system and vice versa.

Highlights

Glioblastoma (GBM) is the most common and aggressive type of primary brain cancer
The calcitonin family of receptors consist of the calcitonin receptor and the calcitonin receptor-like receptor; Ostrovskaya et al BMC Cancer (2019) 19:157 both are class B G protein-coupled receptors (GPCRs)
calcitonin receptor (CTR) is most commonly known for its role in bone and calcium homeostasis, its expression has been demonstrated in a number of cancer cell lines and primary cancers including breast and prostate cancers, bone cancers, leukemia, multiple myeloma, thymic lymphoma and glioblastoma

Summary

Introduction

Glioblastoma (GBM) is the most common and aggressive type of primary brain cancer. With median survival of less than 15 months, identification and validation of new GBM therapeutic targets is of critical importance. A metastatic derivative cell line – PC3M – expresses both CT and CTR and this co-expression appears to form a positive feedback system that increases invasiveness, emphasizing the role of paracrine/autocrine signaling of CT/CTR in this cancer [16, 17]. These data are consistent with the European Medicines Agency report, recommending close monitoring of prostate cancer during the clinical use of CT (EMA/109665/2013). In mouse thymic lymphoma models, where CTR is expressed as an amylin receptor, amylin treatment leads to metabolic reprogramming (switch from glycolysis to oxidative phosphorylation) resulting in increased susceptibility to apoptosis [18, 19]

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