Metformin inhibits the activation of melanocortin receptors 2 and 3 in vitro: A possible mechanism for its anti-androgenic and weight balancing effects in vivo?

Parween, Shaheena; Rihs, Silvia; Flück, Christa E. (2020). Metformin inhibits the activation of melanocortin receptors 2 and 3 in vitro: A possible mechanism for its anti-androgenic and weight balancing effects in vivo? The journal of steroid biochemistry and molecular biology, 200, p. 105684. Elsevier 10.1016/j.jsbmb.2020.105684

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Metformin is recommended as one of the first-line drugs for the treatment of type 2 diabetes and the metabolic syndrome. In addition to its insulin sensitizing effects, it has been shown to attenuate androgen excess in women with polycystic ovary syndrome (PCOS) or congenital adrenal hyperplasia (CAH), as well as to ameliorate obesity. The mechanisms of metformin action seem manifold. Preclinical studies suggest that it inhibits the cellular stress response at the level of the mitochondrial OXPHOS system and through AMPK dependent and independent mechanisms. Recent studies have shown that metformin decreases ACTH secretion from pituitary and reduces ACTH-stimulated adrenal secretion. In this study we investigated its specific effect through the melanocortin receptor 2 (MC2R) on signaling targeting adrenal steroidogenesis. To assess this effect, we used mouse adrenal OS3 cells, which do not express the MC2R. Cells were transfected with the MC2R and stimulated by ACTH. Downstream cyclic AMP production was then assessed by a co-transfected cAMP-responsive vector producing luciferase that was measured by a dual luciferase assay. The amount of luciferase produced in this assay corresponds to the amount of receptor activation with varying amount of ACTH. The effect of metformin was then tested in this system. We found a significant inhibition of ACTH induced MC2R activation and signaling with 10 mM metformin. The ACTH concentration response curve (CRC) was half-log shifted and a ∼30 % reduction in maximum receptor response (Rmax) to ACTH in presence of metformin was observed. This effect was dose dependent with an IC50 of 4.2 mM. qRT-PCR analyses showed that metformin decreased ACTH induced MC2R expression. Metformin did not affect cell viability and basal cAMP levels. We also tested the effect of metformin on homologous melanocortin receptors (MCRs). No significant effect was found on MC1R and MC4R activity. However, a log shift of EC50 of ACTH stimulation on MC3R was observed with metformin treatment. Metformin also inhibited melanocortin stimulating hormone (αMSH) induced MC3R activity. In conclusion, we show that metformin acts on MC2R and MC3R signaling directly. The role of MC2R for steroidogenesis is well established. MC3R is involved in energy balance and seems to act as a rheostat when the metabolism is challenged. Our study may explain how metformin helps in weight loss and attenuates the excess response to ACTH in androgen excess disorders such as PCOS and CAH.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > Unit Childrens Hospital > Forschungsgruppe Endokrinologie / Diabetologie / Metabolik (Pädiatrie)
04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Paediatric Medicine
04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Paediatric Medicine > Endocrinology/Metabolic Disorders

UniBE Contributor:

Parween, Shaheena; Rihs, Silvia and Flück Pandey, Christa Emma

Subjects:

600 Technology > 610 Medicine & health
500 Science > 570 Life sciences; biology

ISSN:

1879-1220

Publisher:

Elsevier

Language:

English

Submitter:

Christa Emma Flück Pandey

Date Deposited:

28 Dec 2020 18:33

Last Modified:

03 Jan 2021 02:54

Publisher DOI:

10.1016/j.jsbmb.2020.105684

PubMed ID:

32360359

Uncontrolled Keywords:

ACTH Antagonist MC2R MC3R Metformin OS3 cells Steroidogenesis

BORIS DOI:

10.48350/150412

URI:

https://boris.unibe.ch/id/eprint/150412

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