The bromodomain inhibitor JQ1+ reduces calcium-sensing receptor activity in pituitary cell-lines

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The bromodomain inhibitor JQ1+ reduces calcium-sensing receptor activity in pituitary cell-lines. / Lines, Kate E; Gluck, Anna K; Thongjuea, Supat; Bountra, Chas; Thakker, Rajesh V; Gorvin, Caroline M.

In: Journal of Molecular Endocrinology, Vol. 67, No. 3, 26.07.2021, p. 83-94.

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Lines, Kate E ; Gluck, Anna K ; Thongjuea, Supat ; Bountra, Chas ; Thakker, Rajesh V ; Gorvin, Caroline M. / The bromodomain inhibitor JQ1+ reduces calcium-sensing receptor activity in pituitary cell-lines. In: Journal of Molecular Endocrinology. 2021 ; Vol. 67, No. 3. pp. 83-94.

Bibtex

@article{9f36f4d1174c4253908d6108a915bd9e,
title = "The bromodomain inhibitor JQ1+ reduces calcium-sensing receptor activity in pituitary cell-lines",
abstract = "Corticotrophinomas represent 10% of all surgically removed pituitary adenomas, however, current treatment options are often not effective and there is a need for improved pharmacological treatments. Recently, JQ1+, a bromodomain inhibitor that promotes gene transcription by binding acetylated histone residues and recruiting transcriptional machinery, has been shown to reduce proliferation in a murine corticotroph cell-line, AtT20. RNA-Seq analysis of AtT20 cells following treatment with JQ1+ identified the calcium-sensing receptor (CaSR) gene as significantly downregulated, which was subsequently confirmed using real-time PCR and western blot analysis. CaSR is a G protein-coupled receptor that plays a central role in calcium homeostasis but can elicit non-calcitropic effects in multiple tissues, including the anterior pituitary where it helps regulate hormone secretion. However, in AtT20 cells, CaSR activates a tumour-specific cAMP pathway that promotes ACTH and PTHrP hypersecretion. We hypothesised that the Casr promoter may harbour binding sites for BET proteins, and using chromatin immunoprecipitation (ChIP)-sequencing demonstrated that the BET protein Brd3 binds to the promoter of the Casr gene. Assessment of CaSR signalling showed that JQ1+ significantly reduced Ca2+e-mediated increases in intracellular calcium (Ca2+i) mobilisation and cAMP signalling. However, the CaSR negative allosteric modulator, NPS-2143, was unable to reduce AtT20 cell proliferation, indicating that reducing CaSR expression rather than activity is likely required to reduce pituitary cell proliferation. Thus, these studies demonstrate that reducing CaSR expression may be a viable option in the treatment of pituitary tumours. Moreover, current strategies to reduce CaSR activity, rather than protein expression for cancer treatments, may be ineffective.",
author = "Lines, {Kate E} and Gluck, {Anna K} and Supat Thongjuea and Chas Bountra and Thakker, {Rajesh V} and Gorvin, {Caroline M}",
year = "2021",
month = jul,
day = "26",
doi = "10.1530/JME-21-0030",
language = "English",
volume = "67",
pages = "83--94",
journal = "Journal of Molecular Endocrinology",
issn = "0952-5041",
publisher = "BioScientifica",
number = "3",

}

RIS

TY - JOUR

T1 - The bromodomain inhibitor JQ1+ reduces calcium-sensing receptor activity in pituitary cell-lines

AU - Lines, Kate E

AU - Gluck, Anna K

AU - Thongjuea, Supat

AU - Bountra, Chas

AU - Thakker, Rajesh V

AU - Gorvin, Caroline M

PY - 2021/7/26

Y1 - 2021/7/26

N2 - Corticotrophinomas represent 10% of all surgically removed pituitary adenomas, however, current treatment options are often not effective and there is a need for improved pharmacological treatments. Recently, JQ1+, a bromodomain inhibitor that promotes gene transcription by binding acetylated histone residues and recruiting transcriptional machinery, has been shown to reduce proliferation in a murine corticotroph cell-line, AtT20. RNA-Seq analysis of AtT20 cells following treatment with JQ1+ identified the calcium-sensing receptor (CaSR) gene as significantly downregulated, which was subsequently confirmed using real-time PCR and western blot analysis. CaSR is a G protein-coupled receptor that plays a central role in calcium homeostasis but can elicit non-calcitropic effects in multiple tissues, including the anterior pituitary where it helps regulate hormone secretion. However, in AtT20 cells, CaSR activates a tumour-specific cAMP pathway that promotes ACTH and PTHrP hypersecretion. We hypothesised that the Casr promoter may harbour binding sites for BET proteins, and using chromatin immunoprecipitation (ChIP)-sequencing demonstrated that the BET protein Brd3 binds to the promoter of the Casr gene. Assessment of CaSR signalling showed that JQ1+ significantly reduced Ca2+e-mediated increases in intracellular calcium (Ca2+i) mobilisation and cAMP signalling. However, the CaSR negative allosteric modulator, NPS-2143, was unable to reduce AtT20 cell proliferation, indicating that reducing CaSR expression rather than activity is likely required to reduce pituitary cell proliferation. Thus, these studies demonstrate that reducing CaSR expression may be a viable option in the treatment of pituitary tumours. Moreover, current strategies to reduce CaSR activity, rather than protein expression for cancer treatments, may be ineffective.

AB - Corticotrophinomas represent 10% of all surgically removed pituitary adenomas, however, current treatment options are often not effective and there is a need for improved pharmacological treatments. Recently, JQ1+, a bromodomain inhibitor that promotes gene transcription by binding acetylated histone residues and recruiting transcriptional machinery, has been shown to reduce proliferation in a murine corticotroph cell-line, AtT20. RNA-Seq analysis of AtT20 cells following treatment with JQ1+ identified the calcium-sensing receptor (CaSR) gene as significantly downregulated, which was subsequently confirmed using real-time PCR and western blot analysis. CaSR is a G protein-coupled receptor that plays a central role in calcium homeostasis but can elicit non-calcitropic effects in multiple tissues, including the anterior pituitary where it helps regulate hormone secretion. However, in AtT20 cells, CaSR activates a tumour-specific cAMP pathway that promotes ACTH and PTHrP hypersecretion. We hypothesised that the Casr promoter may harbour binding sites for BET proteins, and using chromatin immunoprecipitation (ChIP)-sequencing demonstrated that the BET protein Brd3 binds to the promoter of the Casr gene. Assessment of CaSR signalling showed that JQ1+ significantly reduced Ca2+e-mediated increases in intracellular calcium (Ca2+i) mobilisation and cAMP signalling. However, the CaSR negative allosteric modulator, NPS-2143, was unable to reduce AtT20 cell proliferation, indicating that reducing CaSR expression rather than activity is likely required to reduce pituitary cell proliferation. Thus, these studies demonstrate that reducing CaSR expression may be a viable option in the treatment of pituitary tumours. Moreover, current strategies to reduce CaSR activity, rather than protein expression for cancer treatments, may be ineffective.

U2 - 10.1530/JME-21-0030

DO - 10.1530/JME-21-0030

M3 - Article

C2 - 34223822

VL - 67

SP - 83

EP - 94

JO - Journal of Molecular Endocrinology

JF - Journal of Molecular Endocrinology

SN - 0952-5041

IS - 3

ER -