The metabolism and receptor interactions of C11-oxy steroids: implications for hormonal homeostasis and pathophysiology

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dc.contributor.advisorSwart, Amanda C. en_ZA
dc.contributor.advisorSnoep, Jacky L. en_ZA
dc.contributor.advisorKaschula, Catherine H.en_ZA
dc.contributor.authorGent, Rachelleen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Biochemistry.en_ZA
dc.date.accessioned2024-03-01T20:52:17Z
dc.date.accessioned2024-04-26T09:12:20Z
dc.date.available2024-03-01T20:52:17Z
dc.date.available2024-04-26T09:12:20Z
dc.date.issued2024-03
dc.descriptionThesis (PhD)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: This study describes: • the determination of the kinetic parameters of the 11,B-hydroxysteroid dehydrogenase type 1 (11,BHSD1) and type 2 (11,BHSD2) isozyme conversion of C11-oxy C21 steroids, 11,B- hydroxyprogesterone (11,BOHP4) and 11-ketoprogesterone (11KP4), and C11-oxy C19 steroids, 11,B-hydroxyandrostenedione (11OHA4) and 11-ketoandrostenedione (11KA4), and 11,B- hydroxytestosterone (11OHT) and 11-ketotestosterone (11KT). • the in vitro conversion of C11-oxy C21 steroids to C11-oxy C19 steroids by cytochrome P450 17a-hydroxylase (CYP17A1) present novel mechanisms whereby metabolites of the C11-oxy C21 backdoor pathway may contribute to androgen excess. The conversion of 11,BOHP4 to 21- deoxycortisol (21dF) and 11OHA4 as well as the conversion of 11KP4 to 21-deoxycortisone (21dE) and 11KA4 are catalysed by the 17a-hydroxylation and 17,20-lyase activity of CYP17A1 in vitro. • the utilisation of cell models (PNT2, VCaP, LNCaP and C4-2B) to demonstrate the possible role of C11-oxy steroids in prostate cancer (PCa) pathophysiology. Assays showed an increase in 11,BHSD2 activity in LNCaP (androgen-dependent castration resistant prostate cancer (CRPC)) and C4-2B (metastatic CRPC) cells compared to PNT2 (normal prostate) and VCaP (PCa model) cell lines. This demonstrates the role of 11,BHSD2 in PCa directing flux to the biosynthesis of 11KT and 11KDHT, potentially contributing to CRPC. In addition, an increase in 11KT production in LNCaP cells is directly associated with an increase in prostate specific antigen. • the in vitro metabolism of the 11,BHSD2 inhibitor, 11a-hydroxyprogesterone (11aOHP4), by CYP17A1 which resulted in the biosynthesis of novel C11a-metabolites, 11a,17a- dihydroxyprogesterone (11a,17a-diOHP4) and 11a-hydroxyandrostenedione (11aOHA4), suggesting the potential presence of novel in vivo C11-oxy pathways. • the pre-receptor regulation of the androgen receptor (AR), progesterone receptor A (PRA) and progesterone receptor B (PRB) by the 11,BHSD catalysed interconversion of the C11-oxy steroids. Specific C11-oxy metabolites act as potential agonists or antagonists of these steroid receptors while also suggesting regulatory roles for 5a-reductase (SRD5A), 17,B-hydroxysteroid dehydrogenase (17,BHSD), 3a-hydroxysteroid dehydrogenase (3aHSD) as well as CYP17A1. • the development and validation of three novel ultra-high performance supercritical fluid chromatography tandem mass spectrometry (UHPSFC-MS/MS) methods for the separation and quantification of C11-oxy C19, C11-oxy C21 and adrenal steroids. The application of these methods in the comprehensive steroid analyses of southern white rhinoceros (Ceratotherium simum simum) faecal samples and of type 2 diabetes (T2D) patient serum samples implicate homeostatic dysregulation of the C11-oxy steroid metabolites in pathophysiologies.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Hierdie studie beskryf: • die bepaling van die kinetiese parameters van die 11,B-hidroksisteroied-dehidrogenase tipe 1 (11,BHSD1) en tipe 2 (11,BHSD2) isosiem omskakeling van die C11-oksi C21 steroiede, 11,B- hidroksiprogesteroon (11,BOHP4) en 11-ketoprogesteroon (11KP4), en van die C11-oksi C19 steroiede, 11,B-hidroksiandrosteendioon (11OHA4) en 11-ketoandrosteendioon (11KA4) asook 11,B-hidroksitestosteroon (11OHT) en 11-ketotestosteroon (11KT). • die in vitro omskakeling van C11-oksi C21 steroiede na C11-oksi C19 steroiede deur sitokroom P450 17a-hidroksilase (CYP17A1), wat dui op 'n nuwe meganisme waardeur metaboliete van die C11- oksi C21 'agterdeur' padweg bydra tot verhoogde androgeen vlakke. Die omskakeling van 11,BOHP4 na 21-deoksikortisol (21dF) en 11OHA4, sowel as die omskakeling van 11KP4 na 21- deoksikortisoon (21dE) en 11KA4, word gekataliseer deur die 17a-hidroksilering en 17,20-liase aktiwiteit van CYP17A1 in vitro. • die gebruik van selmodelle (PNT2, VCaP, LNCaP and C4-2B) wat dui op die moontlike rol van C11-oksi steroiede in prostaatkanker (PCa) met die toename in 11,BHSD2 aktiwiteit in LNCaP, 'n androgeen-afhanklike kastrasieweerstandige prostaatkanker (CRPC) model, en C4-2B, 'n metastatiese CRPC model in vergelyking met PNT2, 'n normale prostaat model en VCaP, 'n PCa model. 11,BHSD2 se rol is gedemonstreer met 'n toename in die biosintese van 11KT en 11KDHT. Dit is ook bewys dat 'n toename in 11KT produksie in LNCaP selle direk verwant hou met 'n toename in prostaat-spesfieke antigeen (PSA). • die in vitro metabolisme van 11a-hydrosiprogesteroon (11aOHP4), 'n 11,BHSD2 inhibeerder, deur CYP17A1, wat aanleiding gee tot die produksie van C11a metaboliete, naamlik 11a,17a- dihidroksiprogesteroon (11a,17a-diOHP4) en 11a-hidroksiandrosteendioon (11aOHA4). Hierdie dui moontlik op die teenwoordigheid van soortgelyke C11-oksi metaboliese paaie in vivo. • Die pre-reseptor regulering van die androgen-reseptor (AR), progesteroon-reseptor-A (PRA) en progesteroon-reseptor-B (PRB) deur die 11,BHSD-gekataliseerde omskakeling van C11- oksisteroiede. Spesifieke C11-oksi metaboliete toon of agoniste of antagoniste aktiwiteit, terwyl 5a-reduktase (SRD5A), 17,B-hidroksisteroied-dehidrogenase (17,BHSD), 3a-hidroksisteroied- dehidrogenase (3aHSD) en CYP17A1 moontlik regulatoriese rolle speel. • die ontwikkeling van drie nuwe ultra-hoe druk superkritiese vloeistof chromatografie tandem massaspektrometrie (UHPSFC-MS/MS) metodes vir die skeiding en konsentrasie bepaling van C11-oksi C19 steroiede, C11-oksi C21 steroiede en byniersteroiede. Die daaropvolgende toepassing van hierdie metodes in omvattende steroiedanalises van suidelike witrenoster (Ceratotherium simum simum) stoelgangmonsters asook van serum monsters van tipe 2 diabetes pasiente, dui op homeostatiese wanregulering van die C11-oksisteroied metaboliete in die progressie van siektetoestande.af_ZA
dc.description.versionDoctoralen_ZA
dc.format.extentxvi, 152 pages : illustrationsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130207
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshSteroids -- Mechanism of actionen_ZA
dc.subject.lcshCancer -- Pathophysiologyen_ZA
dc.subject.lcshSteroids -- Receptorsen_ZA
dc.subject.lcshSteroid hormones -- Receptorsen_ZA
dc.subject.lcshEnzyme inhibitorsen_ZA
dc.subject.nameUCTDen_ZA
dc.titleThe metabolism and receptor interactions of C11-oxy steroids: implications for hormonal homeostasis and pathophysiologyen_ZA
dc.typeThesisen_ZA
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