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Weirath NA, Haskell-Luevano C. Recommended Tool Compounds for the Melanocortin Receptor (MCR) G Protein-Coupled Receptors (GPCRs). ACS Pharmacol Transl Sci 2024; 7:2706-2724. [PMID: 39296259 PMCID: PMC11406693 DOI: 10.1021/acsptsci.4c00129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 07/26/2024] [Accepted: 07/31/2024] [Indexed: 09/21/2024]
Abstract
The melanocortin receptors are a centrally and peripherally expressed family of Class A GPCRs with physiological roles, including pigmentation, steroidogenesis, energy homeostasis, and others yet to be fully characterized. There are five melanocortin receptor subtypes that, apart from the melanocortin-2 receptor (MC2R), are stimulated by a shared set of endogenous agonists. Until 2020, X-ray crystallographic and cryo-electron microscopic (cryo-EM) structures of these receptors were unavailable, and the investigation of their mechanisms of action and putative ligand-receptor interactions was driven by site-directed mutagenesis studies of the receptors and targeted structure-activity relationship (SAR) studies of the endogenous and derivative synthetic ligands. Synthetic derivatives of the endogenous agonist ligand α-MSH have evolved into a suite of powerful ligands such as NDP-MSH (melanotan I), melanotan II (MTII), and SHU9119. This suite of tool compounds now enables the study of the melanocortin receptors and serves as scaffolds for FDA-approved drugs, means of validating stably expressing melanocortin receptor cell lines, core ligands in assessing cryo-EM structures of active and inactive receptor complexes, and essential references for high-throughput discovery and mechanism of action studies. Herein, we review the history and significance of a finite set of these essential tool compounds and discuss how they are being utilized to further the field's understanding of melanocortin receptor physiology and greater druggability.
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Affiliation(s)
- Nicholas A Weirath
- Department of Medicinal Chemistry & Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Carrie Haskell-Luevano
- Department of Medicinal Chemistry & Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
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2
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Upadhyay PR, Swope VB, Starner RJ, Koikov L, Abdel-Malek ZA. Journey through the spectacular landscape of melanocortin 1 receptor. Pigment Cell Melanoma Res 2024. [PMID: 38857302 DOI: 10.1111/pcmr.13180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 05/13/2024] [Accepted: 05/29/2024] [Indexed: 06/12/2024]
Abstract
The physiological role of α-melanocyte stimulating hormone in regulating integumental pigmentation of many vertebrate species has been recognized since the 1960's. However, its physiological significance for human pigmentation remained enigmatic until the 1990's. α-Melanocyte stimulating hormone and related melanocortins are synthesized locally in the skin, primarily by keratinocytes, in addition to the pituitary gland, and therefore act as paracrine factors for melanocytes. Human melanocytes express the melanocortin 1 receptor, which recognizes α-melanocyte stimulating hormone and the related adrenocorticotropic hormone as agonists. This review summarizes the current knowledge of the pleotropic effects of the activated melanocortin 1 receptor that maintain human melanocyte homeostasis by regulating melanogenesis and the response to environmental stressors, mainly solar radiation. Certain allelic variants of the melanocortin 1 receptor gene are associated with specific pigmentary phenotypes in various human populations. Variants associated with red hair phenotype compromise the function of the encoded receptor. Activation of the human melanocortin 1 receptor regulates eumelanin synthesis and enhances DNA damage response of melanocytes to solar radiation and oxidative stressors. We describe how synthetic selective melanocortin 1 receptor agonists can be efficacious as sunless tanning agents, for treatment of vitiligo and photosensitivity disorders, and for prevention of skin cancer, including melanoma.
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Affiliation(s)
- P R Upadhyay
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - V B Swope
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - R J Starner
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - L Koikov
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Z A Abdel-Malek
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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3
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Zhou Y, Mowlazadeh Haghighi S, Sawyer JR, Hruby VJ, Cai M. Ψ and χ Angle Constrains at the C-Terminus Trp Position of the Melanotropin Tetrapeptide Ac-His-d-Phe-Arg-Trp-NH 2 Lead to Potent and Selective Agonists at hMC1R and hMC4R. J Med Chem 2023; 66:6715-6724. [PMID: 37133411 DOI: 10.1021/acs.jmedchem.2c01794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Melanocortin receptors (MCRs) are a family of G protein-coupled receptors that regulate important physiological functions. Yet, drug development targeting MCRs is hindered by potential side effects due to a lack of receptor subtype-selective ligands with bioavailability. Here, we report novel synthetic pathways to introduce Ψ and χ angle constraints at the C-terminus Trp position of the nonselective prototype tetrapeptide agonist Ac-His-d-Phe-Arg-Trp-NH2. With these conformational constraints, peptide 1 (Ac-His-d-Phe-Arg-Aia) shows improved selectivity at hMC1R, with an EC50 of 11.2 nM for hMC1R and at least 15-fold selectivity compared to other MCR subtypes. Peptide 3 (Ac-His-pCF3-d-Phe-Arg-Aia) is a potent and selective hMC4R agonist with an EC50 of 4.1 nM at hMC4R and at least ninefold selectivity. Molecular docking studies reveal that the Ψ and χ angle constraints force the C-terminal Aia residue to flip and interact with TM6 and TM7, a feature that we hypothesize leads to the receptor subtype selectivity.
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Affiliation(s)
- Yang Zhou
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Saghar Mowlazadeh Haghighi
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Jonathon R Sawyer
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Victor J Hruby
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Minying Cai
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
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Xie B, Zhu Y, Shen Y, Xu W, Song X. Treatment update for vitiligo based on autoimmune inhibition and melanocyte protection. Expert Opin Ther Targets 2023; 27:189-206. [PMID: 36947026 DOI: 10.1080/14728222.2023.2193329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
INTRODUCTION The treatment of vitiligo remains challenging due to the complexity of its pathogenesis, influenced by genetic factors, oxidative stress and abnormal cell adhesion that collectively impact melanocyte survival and trigger immune system attacks, resulting in melanocyte death. Melanocytes in vitiligo are believed to exhibit genetic susceptibility and defects in cellular mechanisms, such as defects in autophagy, that reduce their ability to resist oxidative stress, leading to increased expression of the pro-inflammatory protein HSP70. The low expression of adhesion molecules, such as DDR1 and E-cadherin, accelerates melanocyte damage and antigen exposure. Consequently, autoimmune attacks centered on IFN-γ-CXCR9/10-CXCR3-CD8+ T cells are initiated, causing vitiligo. AREAS COVERED This review discusses the latest knowledge on the pathogenesis of vitiligo and potential therapeutic targets from the perspective of suppressing autoimmune attacks and activating melanocytes functions. EXPERT OPINION Vitiligo is one of the most challenging dermatological diseases due to its complex pathogenesis with diverse therapeutic targets. Immune suppression, such as corticosteroids and emerging JAK inhibitors, has proven effective in disease progression. However, during the early stages of the disease, it is also important to optimize therapeutic strategies to activate melanocytes for alleviating oxidative stress and improving treatment outcomes.
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Affiliation(s)
- Bo Xie
- Department of Dermatology, Hangzhou Third People's Hospital, Hangzhou Third Hospital Affiliated to Zhejiang Chinese Medical University, Affiliated Hangzhou Dermatology Hospital, Zhejiang University School of Medicine; West Lake Ave 38, Hangzhou, 310009, People's Republic of China
| | - Yuqi Zhu
- Department of Dermatology, Hangzhou Third People's Hospital, Hangzhou Third Hospital Affiliated to Zhejiang Chinese Medical University, Affiliated Hangzhou Dermatology Hospital, Zhejiang University School of Medicine; West Lake Ave 38, Hangzhou, 310009, People's Republic of China
- Zhejiang Chinese Medical University; Binwen Rd 548, Hangzhou, 310053, People's Republic of China
| | - Yuqing Shen
- Department of Dermatology, Hangzhou Third People's Hospital, Hangzhou Third Hospital Affiliated to Zhejiang Chinese Medical University, Affiliated Hangzhou Dermatology Hospital, Zhejiang University School of Medicine; West Lake Ave 38, Hangzhou, 310009, People's Republic of China
- Zhejiang Chinese Medical University; Binwen Rd 548, Hangzhou, 310053, People's Republic of China
| | - Wen Xu
- Department of Dermatology, Hangzhou Third People's Hospital, Hangzhou Third Hospital Affiliated to Zhejiang Chinese Medical University, Affiliated Hangzhou Dermatology Hospital, Zhejiang University School of Medicine; West Lake Ave 38, Hangzhou, 310009, People's Republic of China
- Zhejiang University School of Medicine; Yuhangtang Rd 866, Hangzhou, 310058, People's Republic of China
| | - Xiuzu Song
- Department of Dermatology, Hangzhou Third People's Hospital, Hangzhou Third Hospital Affiliated to Zhejiang Chinese Medical University, Affiliated Hangzhou Dermatology Hospital, Zhejiang University School of Medicine; West Lake Ave 38, Hangzhou, 310009, People's Republic of China
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5
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White AM, Dellsén A, Larsson N, Kaas Q, Jansen F, Plowright AT, Knerr L, Durek T, Craik DJ. Late-Stage Functionalization with Cysteine Staples Generates Potent and Selective Melanocortin Receptor-1 Agonists. J Med Chem 2022; 65:12956-12969. [PMID: 36167503 DOI: 10.1021/acs.jmedchem.2c00793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this work, cysteine staples were used as a late-stage functionalization strategy to diversify peptides and build conjugates targeting the melanocortin G-protein-coupled receptors [melanocortin receptor-1 (MC1R) and MC3R-MC5R]. Monocyclic and bicyclic agonists based on sunflower trypsin inhibitor-1 were used to generate a selection of stapled peptides that were evaluated for binding (pKi) and functional activation (pEC50) of the melanocortin receptor subtypes. Stapled peptides generally had improved activity, with aromatic stapled peptides yielding selective MC1R agonists, including a xylene-stapled peptide (2) with an EC50 of 1.9 nM for MC1R and >150-fold selectivity for MC3R and MC4R. Selected stapled peptides were further functionalized with linkers and payloads, generating a series of conjugated peptides with potent MC1R activity, including one pyridazine-functionalized peptide (21) with picomolar activity at MC1R (Ki 58 pM; EC50 < 9 pM). This work demonstrates that staples can be used as modular synthetic tools to tune potency and selectivity in peptide-based drug design.
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Affiliation(s)
- Andrew M White
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Anita Dellsén
- Mechanistic Biology & Profiling, Discovery Sciences, R&D, AstraZeneca, Gothenburg 43183, Sweden
| | - Niklas Larsson
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg 43183, Sweden
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Frank Jansen
- Mechanistic Biology & Profiling, Discovery Sciences, R&D, AstraZeneca, Gothenburg 43183, Sweden
| | - Alleyn T Plowright
- Medicinal Chemistry, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg 43183, Sweden
| | - Laurent Knerr
- Medicinal Chemistry, Research and Early Development, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg 43183, Sweden
| | - Thomas Durek
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
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Ji RL, Tao YX. Melanocortin-1 receptor mutations and pigmentation: Insights from large animals. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 189:179-213. [PMID: 35595349 DOI: 10.1016/bs.pmbts.2022.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The melanocortin-1 receptor (MC1R) is a G protein-coupled receptor expressed in cutaneous and hair follicle melanocytes, and plays a central role in coat color determination in vertebrates. Numerous MC1R variants have been identified in diverse species. Some of these variants have been associated with specific hair and skin color phenotypes in humans as well as coat color in animals. Gain-of-function mutations of the MC1R gene cause dominant or partially dominant black/dark coat color, and loss-of-function mutations of the MC1R gene cause recessive or partially recessive red/yellow/pale coat color phenotypes. These have been well documented in a large number of mammals, including human, dog, cattle, horse, sheep, pig, and fox. Higher similarities between large mammals and humans makes them better models to understand pathogenesis of human diseases caused by MC1R mutations. High identities in MC1Rs and similar variants identified in both humans and large mammals also provide an opportunity for receptor structure and function study. In this review, we aim to summarize the naturally occurring mutations of MC1R in humans and large animals.
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Affiliation(s)
- Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States.
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Gimenez LE, Noblin TA, Williams SY, Mullick Bagchi S, Ji RL, Tao YX, Jeppesen CB, Conde-Frieboes KW, Sawyer TK, Grieco P, Cone RD. Demonstration of a Common DPhe 7 to DNal(2') 7 Peptide Ligand Antagonist Switch for Melanocortin-3 and Melanocortin-4 Receptors Identifies the Systematic Mischaracterization of the Pharmacological Properties of Melanocortin Peptides. J Med Chem 2022; 65:5990-6000. [PMID: 35404053 PMCID: PMC9059122 DOI: 10.1021/acs.jmedchem.1c01295] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Melanocortin peptides containing a 3-(2-naphthyl)-d-alanine residue in position 7 (DNal(2')7), reported as melanocortin-3 receptor (MC3R) subtype-specific agonists in two separate publications, were found to lack significant MC3R agonist activity. The cell lines used at the University of Arizona for pharmacological characterization of these peptides, consisting of HEK293 cells stably transfected with human melanocortin receptor subtypes MC1R, MC3R, MC4R, or MC5R, were then obtained and characterized by quantitative polymerase chain reaction (PCR). While the MC1R cell line correctly expressed only hMCR1, the three other cell lines were mischaracterized with regard to receptor subtype expression. The demonstration that a 3-(2-naphthyl)-d-alanine residue in position 7, irrespective of the melanocortin peptide template, results primarily in the antagonism of MC3R and MC4R then allowed us to search the published literature for additional errors. The erroneously characterized DNal(2')7-containing peptides date back to 2003; thus, our analysis suggests that systematic mischaracterization of the pharmacological properties of melanocortin peptides occurred.
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Affiliation(s)
- Luis E. Gimenez
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States,
| | - Terry A. Noblin
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Savannah Y. Williams
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | - Ren-Lei Ji
- Department
of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849, United States
| | - Ya-Xiong Tao
- Department
of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849, United States
| | | | | | - Tomi K. Sawyer
- Courage
Therapeutics, 64 Homer
Street, Newton, Massachusetts 02459, United States
| | - Paolo Grieco
- #Department of Pharmacy and ∇CIRPEB, Centro Interuniversitario
di Ricerca sui
Peptidi Bioattivi, University of Naples,
Federico II, Naples 80131, Italy
| | - Roger D. Cone
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States,Department
of Molecular and Integrative Physiology, School of Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States,
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8
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Discovery of a functionally selective ghrelin receptor (GHSR 1a) ligand for modulating brain dopamine. Proc Natl Acad Sci U S A 2022; 119:e2112397119. [PMID: 35239443 PMCID: PMC8915830 DOI: 10.1073/pnas.2112397119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The modulation of growth hormone secretagogue receptor-1a (GHSR1a) signaling is a promising strategy for treating brain conditions of metabolism, aging, and addiction. GHSR1a activation results in pleiotropic physiological outcomes through distinct and pharmacologically separable G protein– and β-arrestin (βarr)–dependent signaling pathways. Thus, pathway-selective modulation can enable improved pharmacotherapeutics that can promote therapeutic efficacy while mitigating side effects. Here, we describe the discovery of a brain-penetrant small molecule, N8279 (NCATS-SM8864), that biases GHSR1a conformations toward Gαq activation and reduces aberrant dopaminergic behavior in mice. N8279 represents a promising chemical scaffold to advance the development of better treatments for GHSR1a-related brain disorders involving the pathological dysregulation of dopamine. The growth hormone secretagogue receptor-1a (GHSR1a) is the cognate G protein–coupled receptor (GPCR) for the peptide hormone ghrelin. GHSR1a is a promising therapeutic target for a wide range of metabolic, age-related, and central nervous system (CNS)–based conditions. In addition, growing evidence supports that GHSR1a is a modulator of dopamine (DA) homeostasis and is neuroprotective within brain DA circuits. GHSR1a signaling originates from pharmacologically separable G protein– and β-arrestin (βarr)–dependent pathways, and consequently, GHSR1a-mediated physiological responses depend upon their distinctive signaling contributions. Thus, when treating disorders of disrupted DA homeostasis, a pharmacological strategy that modulates biased GHSR1a signaling may uncouple desired therapeutic outcomes from unwanted side effects. Here, we report the discovery of a small molecule GHSR1a agonist, N8279 (NCATS-SM8864), functionally selective for G protein signaling. Comprehensive pharmacological characterization reveals that N8279 elicits potent Gαq activity at the apo- and ghrelin-bound GHSR1a. Further biochemical analysis and molecular modeling demonstrate that N8279 signaling requires the extracellular domain of GHSR1a, especially extracellular loop 2. Collectively, these findings suggest that N8279 possesses an extended binding mode into the extracellular vestibule of the GHSR1a that preferentially favors Gαq signaling over alternative G proteins and βarr2-dependent cellular responses. Critically, N8279 is brain-penetrant in mice, exhibits CNS stability, and attenuates dysfunctional DA-mediated behaviors in both genetic and pharmacological mouse models of hyperdopaminergia. Our findings provide insight into the mechanisms governing GPCR functional selectivity and emphasize how biased ligand drug development can produce novel GHSR1a pharmacotherapeutics to treat pathological disruptions of brain DA homeostasis.
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Tomassi S, Dimmito MP, Cai M, D’Aniello A, Del Bene A, Messere A, Liu Z, Zhu T, Hruby VJ, Stefanucci A, Cosconati S, Mollica A, Di Maro S. CLIPSing Melanotan-II to Discover Multiple Functionally Selective hMCR Agonists. J Med Chem 2022; 65:4007-4017. [DOI: 10.1021/acs.jmedchem.1c01848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Stefano Tomassi
- Dipartimento di Farmacia, Università degli Studi di Napoli “Federico II”, Via D. Montesano 49, Naples 80131, Italy
| | - Marilisa Pia Dimmito
- Dipartimento di Farmacia, Università di Chieti-Pescara “G. d’Annunzio”, Via dei Vestini 31, Chieti 66100, Italy
| | - Minying Cai
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Antonia D’Aniello
- DiSTABiF, University of Campania “Luigi Vanvitelli”, Via Vivaldi 43, 81100 Caserta, Italy
| | - Alessandra Del Bene
- DiSTABiF, University of Campania “Luigi Vanvitelli”, Via Vivaldi 43, 81100 Caserta, Italy
| | - Anna Messere
- DiSTABiF, University of Campania “Luigi Vanvitelli”, Via Vivaldi 43, 81100 Caserta, Italy
| | - Zekun Liu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Tingyi Zhu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Victor J. Hruby
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Azzurra Stefanucci
- Dipartimento di Farmacia, Università di Chieti-Pescara “G. d’Annunzio”, Via dei Vestini 31, Chieti 66100, Italy
| | - Sandro Cosconati
- DiSTABiF, University of Campania “Luigi Vanvitelli”, Via Vivaldi 43, 81100 Caserta, Italy
| | - Adriano Mollica
- Dipartimento di Farmacia, Università di Chieti-Pescara “G. d’Annunzio”, Via dei Vestini 31, Chieti 66100, Italy
| | - Salvatore Di Maro
- DiSTABiF, University of Campania “Luigi Vanvitelli”, Via Vivaldi 43, 81100 Caserta, Italy
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A TRP Family Based Signature for Prognosis Prediction in Head and Neck Squamous Cell Carcinoma. JOURNAL OF ONCOLOGY 2022; 2022:8757656. [PMID: 35140788 PMCID: PMC8820906 DOI: 10.1155/2022/8757656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 12/17/2021] [Indexed: 12/17/2022]
Abstract
Purpose Head and neck squamous cell carcinoma (HNSCC) is a classical type of head and neck cancers, with heterogeneous clinical outcome. This project is set out to create a robust risk signature based on TRP family genes (TFGs) for prognosis evaluation in HNSCC. Methods Based on the HNSCC sample data from the TCGA website, we integrated expression profile of TFGs for 490 HNSCC cases. We explore the interactions among TFGs using STRING tool. The TFGs-based signature (TFBS) was created by Cox relative analyses. In addition, we conducted GSEA to identify the underlying signaling pathways of the specific TFGs in HNSCC. The immune landscape of HNSCC patients was analyzed by CIBERSORT and ssGSEA algorithms. Results A total of 6 TFGs (TRPC1, TRPC3, TRPC6, TRPV2, TRPV4, and TRPM8) closely associated with prognosis of HNSCC cases were screened to create TFBS. TFBS predicted that the TFBS-high group presented dismal patient outcome. Cox regression revealed the favorable independent value of TFBS. ROC analysis showed the robust power of TFBS for prognosis forecasting. GSEA determined several crucial pathways related with HNSCC, which are the p53 pathway, TNF-alpha signaling via NFKB, and hypoxia. Moreover, immune-related analysis showed that patients in the TFBS-high group were more likely in immunosuppressive status. Conclusion Our proposed TFBS could serve as a favorable indicator to forecast the survival outcome of HNSCC cases and offer prominent therapy guidance.
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11
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Guida S, Guida G, Goding CR. MC1R Functions, Expression, and Implications for Targeted Therapy. J Invest Dermatol 2021; 142:293-302.e1. [PMID: 34362555 DOI: 10.1016/j.jid.2021.06.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 06/14/2021] [Accepted: 06/17/2021] [Indexed: 12/23/2022]
Abstract
The G protein-coupled MC1R is expressed in melanocytes and has a pivotal role in human skin pigmentation, with reduced function in human genetic variants exhibiting a red hair phenotype and increased melanoma predisposition. Beyond its role in pigmentation, MC1R is increasingly recognized as promoting UV-induced DNA damage repair. Consequently, there is mounting interest in targeting MC1R for therapeutic benefit. However, whether MC1R expression is restricted to melanocytes or is more widely expressed remains a matter of debate. In this paper, we review MC1R function and highlight that unbiased analysis suggests that its expression is restricted to melanocytes, granulocytes, and the brain.
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Affiliation(s)
- Stefania Guida
- Dermatology Unit, Surgical, Medical and Dental Department of Morphological Sciences Related to Transplant, Oncological and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy.
| | - Gabriella Guida
- Molecular Biology Section, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Colin Ronald Goding
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
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12
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Yeo GSH, Chao DHM, Siegert AM, Koerperich ZM, Ericson MD, Simonds SE, Larson CM, Luquet S, Clarke I, Sharma S, Clément K, Cowley MA, Haskell-Luevano C, Van Der Ploeg L, Adan RAH. The melanocortin pathway and energy homeostasis: From discovery to obesity therapy. Mol Metab 2021; 48:101206. [PMID: 33684608 PMCID: PMC8050006 DOI: 10.1016/j.molmet.2021.101206] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 02/28/2021] [Accepted: 03/03/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Over the past 20 years, insights from human and mouse genetics have illuminated the central role of the brain leptin-melanocortin pathway in controlling mammalian food intake, with genetic disruption resulting in extreme obesity, and more subtle polymorphic variations influencing the population distribution of body weight. At the end of 2020, the U.S. Food and Drug Administration (FDA) approved setmelanotide, a melanocortin 4 receptor agonist, for use in individuals with severe obesity due to either pro-opiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency. SCOPE OF REVIEW Herein, we chart the melanocortin pathway's history, explore its pharmacology, genetics, and physiology, and describe how a neuropeptidergic circuit became an important druggable obesity target. MAJOR CONCLUSIONS Unravelling the genetics of the subset of severe obesity has revealed the importance of the melanocortin pathway in appetitive control; coupling this with studying the molecular pharmacology of compounds that bind melanocortin receptors has brought a new obesity drug to the market. This process provides a drug discovery template for complex disorders, which for setmelanotide took 25 years to transform from a single gene into an approved drug.
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Affiliation(s)
- Giles S H Yeo
- MRC Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK.
| | | | - Anna-Maria Siegert
- MRC Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK.
| | - Zoe M Koerperich
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA 55455.
| | - Mark D Ericson
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA 55455.
| | - Stephanie E Simonds
- Metabolism, Diabetes, and Obesity Programme, Monash Biomedicine Discovery Institute, and Department of Physiology, Monash University, Clayton, Victoria, Australia.
| | - Courtney M Larson
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA 55455.
| | - Serge Luquet
- Université de Paris, BFA, UMR 8251, CNRS, Paris, France.
| | - Iain Clarke
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, VIC 3010, Australia.
| | | | - Karine Clément
- Assistance Publique Hôpitaux de Paris, Nutrition Department, Pitié-Salpêtrière Hospital, Paris, France, Sorbonne Université, INSERM, Nutrition and Obesity: Systemic Approaches (NutriOmics) Research Unit, Paris, France.
| | - Michael A Cowley
- Metabolism, Diabetes, and Obesity Programme, Monash Biomedicine Discovery Institute, and Department of Physiology, Monash University, Clayton, Victoria, Australia.
| | - Carrie Haskell-Luevano
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA 55455.
| | | | - Roger A H Adan
- Department of Translational Neuroscience, UMCU Brain Centre, University Medical Centre Utrecht, Utrecht University, the Netherlands; Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Sweden.
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13
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Koikov L, Starner RJ, Swope VB, Upadhyay P, Hashimoto Y, Freeman KT, Knittel JJ, Haskell-Luevano C, Abdel-Malek ZA. Development of hMC1R Selective Small Agonists for Sunless Tanning and Prevention of Genotoxicity of UV in Melanocytes. J Invest Dermatol 2021; 141:1819-1829. [PMID: 33609553 DOI: 10.1016/j.jid.2020.11.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/12/2020] [Accepted: 11/19/2020] [Indexed: 12/30/2022]
Abstract
Activation of the human melanocortin 1 receptor (hMC1R) expressed on melanocytes by α-melanocortin plays a central role in regulating human pigmentation and reducing the genotoxicity of UV by activating DNA repair and antioxidant defenses. For the development of a hMC1R-targeted photoprotection strategy, we designed tetra- and tripeptide agonists with modifications that provide the necessary lipophilicity and hMC1R selectivity to be effective drugs. These peptides proved to be superior to most of the existing analogs of the physiological tridecapeptide α-melanocortin because of their small size and high hMC1R selectivity. Testing on primary cultures of human melanocytes showed that these peptides are highly potent with prolonged stimulation of melanogenesis, enhanced repair of UV-induced DNA photoproducts, and reduced apoptosis. One of the tripeptides, designated as LK-514 (5), with a molecular weight of 660 Da, has unprecedented (>100,000) hMC1R selectivity when compared with the other melanocortin receptors hMC3R, hMC4R, and hMC5R, and increases pigmentation (sunless tanning) in a cultured, three-dimensional skin model. These new analogs should be efficacious in preventing skin cancer, including melanoma, and treatment of skin disorders, such as vitiligo and polymorphic light eruptions.
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Affiliation(s)
- Leonid Koikov
- Department of Dermatology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Renny J Starner
- Department of Dermatology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Viki B Swope
- Department of Dermatology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Parth Upadhyay
- Department of Dermatology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Yuki Hashimoto
- Department of Dermatology, Toho University, Tokyo, Japan
| | - Katie T Freeman
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - James J Knittel
- Department of Pharmaceutical and Administrative Sciences, Western New England University, Springfield, Massachusetts, USA
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14
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Dinparastisaleh R, Mirsaeidi M. Antifibrotic and Anti-Inflammatory Actions of α-Melanocytic Hormone: New Roles for an Old Player. Pharmaceuticals (Basel) 2021; 14:ph14010045. [PMID: 33430064 PMCID: PMC7827684 DOI: 10.3390/ph14010045] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 12/16/2022] Open
Abstract
The melanocortin system encompasses melanocortin peptides, five receptors, and two endogenous antagonists. Besides pigmentary effects generated by α-Melanocytic Hormone (α-MSH), new physiologic roles in sexual activity, exocrine secretion, energy homeostasis, as well as immunomodulatory actions, exerted by melanocortins, have been described recently. Among the most common and burdensome consequences of chronic inflammation is the development of fibrosis. Depending on the regenerative capacity of the affected tissue and the quality of the inflammatory response, the outcome is not always perfect, with the development of some fibrosis. Despite the heterogeneous etiology and clinical presentations, fibrosis in many pathological states follows the same path of activation or migration of fibroblasts, and the differentiation of fibroblasts to myofibroblasts, which produce collagen and α-SMA in fibrosing tissue. The melanocortin agonists might have favorable effects on the trajectories leading from tissue injury to inflammation, from inflammation to fibrosis, and from fibrosis to organ dysfunction. In this review we briefly summarized the data on structure, receptor signaling, and anti-inflammatory and anti-fibrotic properties of α-MSH and proposed that α-MSH analogues might be promising future therapeutic candidates for inflammatory and fibrotic diseases, regarding their favorable safety profile.
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Affiliation(s)
- Roshan Dinparastisaleh
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21218, USA;
| | - Mehdi Mirsaeidi
- Division of Pulmonary and Critical Care, University of Miami, Miami, FL 33146, USA
- Correspondence: ; Tel.: +1-305-243-1377
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15
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Zhou Y, Mowlazadeh Haghighi S, Liu Z, Wang L, Hruby VJ, Cai M. Development of Ligand-Drug Conjugates Targeting Melanoma through the Overexpressed Melanocortin 1 Receptor. ACS Pharmacol Transl Sci 2020; 3:921-930. [PMID: 33073191 DOI: 10.1021/acsptsci.0c00072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Indexed: 12/31/2022]
Abstract
Melanoma is a lethal form of skin cancer. Despite recent breakthroughs of BRAF-V600E and PD-1 inhibitors showing remarkable clinical responses, melanoma can eventually survive these targeted therapies and become resistant. To solve the drug resistance issue, we designed and synthesized ligand-drug conjugates that couple cytotoxic drugs, which have a low cancer resistance issue, with the melanocortin 1 receptor (MC1R) agonist melanotan-II (MT-II), which provides specificity to MC1R-overexpressing melanoma. The drug-MT-II conjugates maintain strong binding interactions to MC1R and induce selective drug delivery to A375 melanoma cells through its MT-II moiety in vitro. Furthermore, using camptothecin as the cytotoxic drug, camptothecin-MT-II (compound 1) can effectively inhibit A375 melanoma cell growth with an IC50 of 16 nM. By providing selectivity to melanoma cells through its MT-II moiety, this approach of drug-MT-II conjugates enables us to have many more options for cytotoxic drug selection, which can be the key to solving the cancer resistant problem for melanoma.
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Affiliation(s)
- Yang Zhou
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Saghar Mowlazadeh Haghighi
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Zekun Liu
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Lingzhi Wang
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Victor J Hruby
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Minying Cai
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
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16
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Winget MD, Ericson MD, Freeman KT, Haskell-Luevano C. Single Nucleotide Polymorphisms in the Melanocortin His-Phe-Arg-Trp Sequences Decrease Tetrapeptide Potency and Efficacy. ACS Med Chem Lett 2020; 11:272-277. [PMID: 32184956 DOI: 10.1021/acsmedchemlett.9b00198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/02/2019] [Indexed: 11/30/2022] Open
Abstract
The melanocortin receptors are stimulated by agonists (α-MSH, β-MSH, γ-MSH, and ACTH) processed from the proopiomelanocortin (POMC) gene transcript and possess a common His-Phe-Arg-Trp tetrapeptide sequence critical for receptor activation. Deficiency in POMC signaling in humans is associated with adrenal insufficiency, altered pigmentation, and rapid, early onset weight gain. Herein, 12 single nucleotide polymorphisms (SNPs) deposited into the Variation Viewer database within the His-Phe-Arg-Trp sequences of ACTH/α-MSH, β-MSH, and γ-MSH were substituted into tetrapeptide scaffolds to examine the in vitro signaling effects of these polymorphisms at the cloned melanocortin receptors. Every polymorphism decreased agonist potency and/or efficacy at the melanocortin receptors assayed, indicating that polymorphisms within the signaling sequence of POMC-derived agonists negatively impacts receptor activation. Future work to incorporate these substitutions into the full-length POMC agonists would confirm these findings, identifying new patient populations that might benefit from therapeutic regiments to treat POMC-deficient signaling.
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Affiliation(s)
- Marshall D. Winget
- Department of Medicinal Chemistry & Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mark D. Ericson
- Department of Medicinal Chemistry & Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Katie T. Freeman
- Department of Medicinal Chemistry & Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Carrie Haskell-Luevano
- Department of Medicinal Chemistry & Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
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17
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Jackson E, Heidl M, Imfeld D, Meeus L, Schuetz R, Campiche R. Discovery of a Highly Selective MC1R Agonists Pentapeptide to Be Used as a Skin Pigmentation Enhancer and with Potential Anti-Aging Properties. Int J Mol Sci 2019; 20:ijms20246143. [PMID: 31817532 PMCID: PMC6940745 DOI: 10.3390/ijms20246143] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/29/2019] [Accepted: 12/02/2019] [Indexed: 12/17/2022] Open
Abstract
One of the first lines of cutaneous defense against photoaging is (a) the synthesis of melanin and (b) the initiation of an oxidative stress response to protect skin against the harmful effects of solar radiation. Safe and selective means to stimulate epidermal pigmentation associated with oxidative stress defense are; however, scarce. Activation of the melanocortin-1 receptor (MC1R) on epidermal melanocytes represents a key step in cutaneous pigmentation initiation and, additionally, it regulates cellular defense mechanisms like oxidative stress and DNA-repair. Thus, making the activation of MC1R an attractive strategy for modulating skin pigmentation and oxidative stress. In this context, we designed and synthesized pentapeptides that act as MC1R agonists. These peptides bound, with high potency, to MC1R and activated cAMP synthesis in CHO cells expressing human MC1R. Using one lead pentapeptide, we could show that this activation of MC1R was specific as testing the activation of other G-protein coupled receptors, including the MC-receptor family, was negative. In vitro efficacy on mouse melanoma cells showed similar potency as for the synthetic MC1R agonist alpha-melanocyte stimulating hormone (NDP-alpha-MSH). Moreover, we could reproduce this activity in human skin tissue culture. The lead pentapeptide was able to induce ex-vivo protein expression of key melanogenesis markers melanocyte inducing transcription factor (MITF), tyrosinase (TYR), and tyrosinase-related protein 1 (TYRP-1). Concerning oxidative stress response, we found that the pentapeptide enhanced the activation of Nrf2 after UVA-irradiation. Our results make this pentapeptide an ideal candidate as a skin pigmentation enhancer that mimics alpha-MSH and may also have anti-photoaging effects on the skin.
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Affiliation(s)
- Eileen Jackson
- DSM Nutritional Products, Personal Care and Aroma, 4303 Kaiseraugst, Switzerland; (E.J.); (M.H.); (D.I.); (R.S.)
| | - Marc Heidl
- DSM Nutritional Products, Personal Care and Aroma, 4303 Kaiseraugst, Switzerland; (E.J.); (M.H.); (D.I.); (R.S.)
| | - Dominik Imfeld
- DSM Nutritional Products, Personal Care and Aroma, 4303 Kaiseraugst, Switzerland; (E.J.); (M.H.); (D.I.); (R.S.)
| | - Laurent Meeus
- EuroscreenFast, a Business Unit of EPICS Therapeutics S.A., 6041 Gosselies, Belgium;
| | - Rolf Schuetz
- DSM Nutritional Products, Personal Care and Aroma, 4303 Kaiseraugst, Switzerland; (E.J.); (M.H.); (D.I.); (R.S.)
| | - Remo Campiche
- DSM Nutritional Products, Personal Care and Aroma, 4303 Kaiseraugst, Switzerland; (E.J.); (M.H.); (D.I.); (R.S.)
- Correspondence:
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18
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Structure⁻Activity Relationships of the Tetrapeptide Ac-His-Arg-( pI)DPhe-Tic-NH 2 at the Mouse Melanocortin Receptors: Modification at the ( pI)DPhe Position Leads to mMC3R Versus mMC4R Selective Ligands. Molecules 2019; 24:molecules24081463. [PMID: 31013889 PMCID: PMC6515519 DOI: 10.3390/molecules24081463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/01/2019] [Accepted: 04/04/2019] [Indexed: 12/23/2022] Open
Abstract
The five melanocortin receptors (MC1R–MC5R) are involved in numerous biological pathways, including steroidogenesis, pigmentation, and food intake. In particular, MC3R and MC4R knockout mice suggest that the MC3R and MC4R regulate energy homeostasis in a non-redundant manner. While MC4R-selective agonists have been utilized as appetite modulating agents, the lack of MC3R-selective agonists has impeded progress in modulating this receptor in vivo. In this study, the (pI)DPhe position of the tetrapeptide Ac-His-Arg-(pI)DPhe-Tic-NH2 (an MC3R agonist/MC4R antagonist ligand) was investigated with a library of 12 compounds. The compounds in this library were found to have higher agonist efficacy and potency at the mouse (m) MC3R compared to the MC4R, indicating that the Arg-DPhe motif preferentially activates the mMC3R over the mMC4R. This observation may be used in the design of new MC3R-selective ligands, leading to novel probe and therapeutic lead compounds that will be useful for treating metabolic disorders.
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19
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Swope VB, Abdel-Malek ZA. MC1R: Front and Center in the Bright Side of Dark Eumelanin and DNA Repair. Int J Mol Sci 2018; 19:E2667. [PMID: 30205559 PMCID: PMC6163888 DOI: 10.3390/ijms19092667] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 08/31/2018] [Accepted: 09/03/2018] [Indexed: 12/17/2022] Open
Abstract
Melanin, the pigment produced by specialized cells, melanocytes, is responsible for skin and hair color. Skin pigmentation is an important protective mechanism against the DNA damaging and mutagenic effects of solar ultraviolet radiation (UV). It is acknowledged that exposure to UV is the main etiological environmental factor for all forms of skin cancer, including melanoma. DNA repair capacity is another major factor that determines the risk for skin cancer. Human melanocytes synthesize eumelanin, the dark brown form of melanin, as well as pheomelanin, which is reddish-yellow in color. The relative rates of eumelanin and pheomelanin synthesis by melanocytes determine skin color and the sensitivity of skin to the drastic effects of solar UV. Understanding the complex regulation of melanocyte function and how it responds to solar UV has a huge impact on developing novel photoprotective strategies to prevent skin cancer, particularly melanoma, the most fatal form, which originates from melanocytes. This review provides an overview of the known differences in the photoprotective effects of eumelanin versus pheomelanin, how these two forms of melanin are regulated genetically and biochemically, and their impact on the DNA damaging effects of UV exposure. Additionally, this review briefly discusses the role of paracrine factors, focusing on α-melanocortin (α-melanocyte stimulating hormone; α-MSH), in regulating melanogenesis and the response of melanocytes to UV, and describes a chemoprevention strategy based on targeting the melanocortin 1 receptor (MC1R) by analogs of its physiological agonist α-MSH.
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Affiliation(s)
- Viki B Swope
- Department of Dermatology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267, USA.
| | - Zalfa A Abdel-Malek
- Department of Dermatology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267, USA.
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