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Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity
Thesis (MSc)--Stellenbosch University, 2022.
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Stellenbosch : Stellenbosch University
2022
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| _version_ | 1867613995533336576 |
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| access_status_str | Open Access |
| author | Janse van Vuuren, Melani |
| author2 | Africander, Donita |
| author_browse | Africander, Donita Janse van Vuuren, Melani |
| author_facet | Africander, Donita Janse van Vuuren, Melani |
| author_sort | Janse van Vuuren, Melani |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/125089 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:45:00.328Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/125089 Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity Janse van Vuuren, Melani Africander, Donita Stellenbosch University. Faculty of Science. Dept. of Biochemistry. Progestational hormones -- Mechanism of action Aromatase Contraception Breast -- Cancer -- Risk factors Menopause -- Hormone therapy Estrogen -- Therapeutic use HIV (Viruses) UCTD Thesis (MSc)--Stellenbosch University, 2022. ENGLISH ABSTRACT: Fluctuations in 17β-estradiol (E2) levels have been associated with several negative effects in female health, including breast cancer development and progression, and susceptibility to human immunodeficiency virus (HIV-1) infection. One factor that may modulate E2 levels, is the clinical use of progestins. Progestins are synthetic ligands designed to mimic the actions of the natural female hormone, progesterone (P4), and are used in either menopausal hormone therapy or hormonal contraception by millions of women. Several studies have implicated the use of some progestins in increased breast cancer risk as well as in the susceptibility to HIV-1 infection. However, multiple progestins have been synthesized with varying biological activities, and only eight have been linked to increased breast cancer risk, while only two, medroxyprogesterone acetate (MPA) and levonorgestrel (LNG), have been associated with increased susceptibility to HIV-1. Interestingly, MPA and LNG, together with norethisterone (NET), are mostly implicated in breast cancer risk. It has been postulated that MPA increases susceptibility to HIV-1 by decreasing E2 levels. Whether this is true for other progestins is not known. Moreover, the mechanism whereby MPA modulates E2 levels is unknown. Since the aromatase enzyme is responsible for synthesizing E2 from testosterone, the aim of this study was to directly compare the effects of a selected panel of progestins, to each other and P4, on aromatase mRNA and protein expression, as well as aromatase activity. Real-time quantitative PCR results showed that P4 and all the progestins, MPA, NET, LNG, drospirenone (DRSP), nomegestrol acetate (NoMAC) and promegestone (R5020) downregulated aromatase mRNA expression in the JEG-3 human placental cell line. While it is known that several promoters in the aromatase gene are expressed in a tissue-specific manner, and that promoter switching does occur is some tissues, we did not observe any promoter switching in the presence of P4 or the progestins. Western blot analysis showed that aromatase protein expression was downregulated by all the progestins in our panel, but not by P4. Experiments in the presence of a progesterone receptor (PR), glucocorticoid receptor, or androgen receptor antagonist, showed that progestin effects on aromatase protein expression is likely mediated by the PR. Using ultra-high performance liquid chromatography tandem mass spectrometry, it was shown that aromatase activity was downregulated by P4 and all progestins evaluated. We did not observe proliferation of the MCF7-BUS cells transiently transfected with aromatase under the experimental conditions used in this study. In summary, these results provide insight into the regulation of E2 levels by progestins and aid in our understanding of progestin mechanisms in HIV-1 and breast cancer biology. AFRIKAANSE OPSOMMING: Fluktuasies in 17β-estradiol (E2)-vlakke word geassossieer met verskeie negatiewe effekte in vroulike gesondheid, insluitend die ontwikkeling en verloop van borskanker, asook die vatbaarheid vir menslike immuniteitsgebreksvirus (MIV-1) infeksie. Een faktor wat E2 vlakke kan moduleer, is die kliniese gebruik van progestiene. Progestiene is sintetiese ligande wat ontwerp is om die aksies van die natuurlike vroulike hormoon, progesteroon (P4) na te boots en word in όf menopousale hormoonterapie óf hormonale voorbehoeding deur miljoene vroue gebruik. Verskeie studies het die gebruik van sommige progestiene geïmpliseer in die verhoogde risiko vir borskanker sowel as in die vatbaarheid vir MIV-1 infeksie. Veelvuldige progestiene is egter gesinteseer met verskillende biologiese aktiwiteite en slegs agt is gekoppel aan verhoogde borskanker risiko, terwyl slegs twee, medroksieprogesteroon asetaat (MPA) en levonorgestrel (LNG), met verhoogde vatbaarheid vir MIV-1 geassossieer is. Interessant genoeg is MPA en LNG tesame met noretisteroon (NET), meestel geïmpliseer in die risiko van borskanker. Daar word gepostuleer dat MPA, vatbaarheid vir MIV-1 verhoog deur E2-vlakke te verlaag. Of dit waar is vir ander progestiene is onbekend. Boonop is die meganisme waardeur MPA E2 vlakke moduleer ook onbekend. Aangesien die aromatase-ensiem verantwoordelik is vir die sintetisering van E2 vanaf testosteroon, was die doel van die huidige studie om die effekte van ‘n geselekteerde paneel van progestiene, met mekaar en P4, op aromatase mRNA en proteïen uitdrukking, sowel as aktiwiteit, direk te vergelyk. Intydse kwantitatiewe polimerase kettingreaksie resultate het getoon dat P4 en al die progestiene, MPA, NET, LNG, drospirenoon (DRSP), nomegesterolasetaat (NoMAC) en promegestoon (R5020) aromatase mRNA uitdrukking in die JEG-3 menslike plasentasellyn, afreguleer. Alhoewel dit bekend is dat verskeie promotors in die aromatase-geen op 'n weefsel-spesifieke wyse uitgedruk word, en dat promotorwisseling wel in sommige weefsels plaasvind, het ons geen promotorwisseling in die teenwoordigheid van P4 of die progestiene waargeneem nie. Westernklad-analise het getoon dat aromatase proteïenuitdrukking deur al die progestiene in ons paneel afgereguleer word, maar nie deur P4 nie. Eksperimente in die teenwoordigheid van 'n progesteroonreseptor (PR), glukokortikoïedreseptor, of androgeenreseptor antagonis, het getoon dat progestieneffekte op aromatase proteïenuitdrukking waarskynlik deur die PR bemiddel word. Deur gebruik te maak van superkritiese vloeistofchromatografie en tandem massaspektrometrie, is getoon dat aromatase-aktiwiteit deur P4 asook al die geëvalueerde progestiene, afgereguleer word. Onder die huidige studie se eksperimentele kondisies is geen proliferasie van die MCF7-BUS selle, kortstondig getransfekteer met aromatase, waargeneem nie. Ter samevatting, bied ons bevindinge insig tot die regulering van E2-vlakke deur progestiene en help met die begrip van progestien-meganismes in MIV-1- en borskankerbiologie. Masters 2022-03-10T07:12:32Z 2022-04-29T12:53:30Z 2023-03-31T03:00:11Z 2022-03 Thesis http://hdl.handle.net/10019.1/125089 en_ZA Stellenbosch University xii, 73 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Progestational hormones -- Mechanism of action Aromatase Contraception Breast -- Cancer -- Risk factors Menopause -- Hormone therapy Estrogen -- Therapeutic use HIV (Viruses) UCTD Janse van Vuuren, Melani Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity |
| title | Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity |
| title_full | Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity |
| title_fullStr | Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity |
| title_full_unstemmed | Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity |
| title_short | Investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity |
| title_sort | investigating the effects of progestins used in contraception and menopausal hormone therapy on aromatase expression and activity |
| topic | Progestational hormones -- Mechanism of action Aromatase Contraception Breast -- Cancer -- Risk factors Menopause -- Hormone therapy Estrogen -- Therapeutic use HIV (Viruses) UCTD |
| url | http://hdl.handle.net/10019.1/125089 |
| work_keys_str_mv | AT jansevanvuurenmelani investigatingtheeffectsofprogestinsusedincontraceptionandmenopausalhormonetherapyonaromataseexpressionandactivity |