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Substrate inhibition of 17β-HSD1 in living cells and regulation of 17β-HSD7 by 17β-HSD1 knockdown
- Source :
- The Journal of Steroid Biochemistry and Molecular Biology. 172:36-45
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- This study addresses first the role of human 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) in breast cancer (BC) cells. The enzyme has a high estrone-activating activity that is subject to strong substrate inhibition as shown by enzyme kinetics at the molecular level. We used BC cells to verify this phenomenon in living cells: estrone concentration increase did reduce the reaction with 0.025 to 4μM substrate. Moreover, 5α-dihydrotestosterone (DHT) demonstrated some inhibition of estrogen activation at both the molecular and cellular levels. The presence of DHT did not change the tendency toward substrate inhibition for estrone conversion, but shifted the inhibition toward higher substrate concentrations. Moreover, a binding study demonstrated that both DHT and dehydroepiandrosterone (DHEA) can be bound to the enzyme, thereby supporting the multi-specificity of 17β-HSD1. We then followed the concentrations of estradiol and performed q-RT-PCR measurements of reductive 17β-HSDs after 17β-HSD1 inhibition. The estradiol decrease by the 17β-HSD1 inhibition was demonstrated lending support to this observation. Knockdown and inhibition of 17β-HSD1 produced reduction in estradiol levels and the down-regulation of another reductive enzyme 17β-HSD7, thus "amplifying" the reduction of estradiol by the 17β-HSD1 modulation itself. The critical positioning of 17β-HSD7 in sex-hormone-regulation as well as the mutual regulation of steroid enzymes via estradiol in BC, are clearly demonstrated. Our study demonstrates that fundamental enzymological mechanisms are relevant in living cells. Moreover, further enzyme study in cells is merited to advance biological and medical research. We also demonstrated the central role of 17β-HSD7 in sex-hormone conversion and regulation, supporting it as a novel target for estrogen-dependent (ER+) BC.
- Subjects :
- Models, Molecular
0301 basic medicine
17-Hydroxysteroid Dehydrogenases
medicine.drug_class
Placenta
Endocrinology, Diabetes and Metabolism
medicine.medical_treatment
Clinical Biochemistry
Gene Expression
Dehydroepiandrosterone
Dehydrogenase
Estrone
Biochemistry
Protein Structure, Secondary
Substrate Specificity
Steroid
03 medical and health sciences
chemistry.chemical_compound
0302 clinical medicine
Endocrinology
Pregnancy
Cell Line, Tumor
medicine
Humans
Enzyme kinetics
RNA, Small Interfering
Molecular Biology
Feedback, Physiological
chemistry.chemical_classification
Binding Sites
Estradiol
Substrate (chemistry)
Dihydrotestosterone
Epithelial Cells
Cell Biology
Kinetics
030104 developmental biology
Enzyme
chemistry
Estrogen
030220 oncology & carcinogenesis
MCF-7 Cells
Molecular Medicine
Female
hormones, hormone substitutes, and hormone antagonists
Protein Binding
Subjects
Details
- ISSN :
- 09600760
- Volume :
- 172
- Database :
- OpenAIRE
- Journal :
- The Journal of Steroid Biochemistry and Molecular Biology
- Accession number :
- edsair.doi.dedup.....3cf6562308b488e00a22d5126a02b738