Molecular characterisation of MC2R/MRAP antagonists for the treatment of ACTH excess in pituitary and neuroendocrine tumours.

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Pituitary and neuroendocrine tumours (NETs) are known to secrete adrenocorticotropic hormone (ACTH), which acts on the adrenal gland to stimulate glucocorticoid (GC) production. GC excess worsens prognosis (1). Identifying and removal of the source of this excessive plasma ACTH is preferred but not always possible (1,2). Hence, the ability to effectively block the effects ACTH has important clinical utility. ACTH acts on its specific receptor, the melanocortin-2-receptor (MC2R) complexed to the MC2R accessory protein (MRAP). The project is to develop and characterise small molecule compounds that can specifically inhibit the MC2R/MRAP complex for the treatment of pituitary tumours and NETs. There is growing awareness of a need to develop ACTH antagonists to treat ACTH excess (3). The MC2R/MRAP complex is unique responding specifically to ACTH (4,5). We previously identified small molecules that specifically inhibited ACTH stimulated cAMP generation in HEK293-cells co-expressing MC2R/MRAP (3). The overarching aim is to characterize MC2R/MRAP antagonists at a molecular and physiological level. , starting with our own lead compounds (788/0371/9018/6741) with additional compounds as they are identified by our industrial partner. Aim 1. Characterization of MC2R/MRAP antagonists. The student will characterise the antagonist effect on MC2R/MRAP biologyinteraction, binding, signalling and receptor internalisation in real-time.. Techniques include: NanoBRET binding assays, cAMP accumulation assays using luciferase biosensors, p-Glo, or Ca2+ mobilization using the Gcamp6 fluorescent biosensor, beta-arrestin recruitment and G-protein recruitment using nanoBit complementation. With our industrial partners,At OMass they will experience drug modelling and discovery. Aim 2. Effects of MC2R/MRAP antagonists on ACTH stimulated steroid production. Currently, there are no ACTH responsive, glucocorticoid producing adrenal cell-lines available representative of typical adrenocortical cells. Therefore, the student will use murine and human primary adrenal cell cultures to study GC and steroid production with/without MC2R/MRAP antagonists. , by ELISA and mass-spectrometry. Aim 3: Determine effectiveness of MC2R/MRAP antagonists in animal models of ACTH excess. The student will measure GC/steroid production after administering MC2R/MRAP antagonists IP/IV/PO in our murine model of ACTH excess where ACTH is delivered via an osmotic pump. The student will be trained in state-of-the-art pharmacology/receptor signalling techniques and acquire skills working with primary cell cultures and the latest murine models. The supervising team are experts in their field and have a team of technicians, post-docs and research co-ordinators to support the student. Together with an industrial placement at one of the UKs most exciting new biotech companies, they will gain technical and transferable skills sought after in both academia and industry.