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Toward the identification of a function of the "orphan" enzyme DHRS7

Araya, Selene. Toward the identification of a function of the "orphan" enzyme DHRS7. 2018, Doctoral Thesis, University of Basel, Faculty of Science.

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Official URL: http://edoc.unibas.ch/diss/DissB_12764

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Abstract

The short chain dehydrogenase DHRS7 has been previously described as a possible tumor suppressor,
regulated during prostate cancer progression, with the potential of being a marker of prostate cancer.
However, the function of DHRS7 and substrates with good affinity to be of potential physiological meaning
remains unknown leaving it still classified as an “orphan” enzyme. These observations furthered the need
to identify physiologically relevant substrates and understand the mechanisms affected by DHRS7 in
endogenously expressing cell lines. In this thesis, in vitro assays were performed to help to characterize
the activity of DHRS7. They showed DHRS7 has 3α and 20β reductase activities on the carbonyl of steroidal
substrates, and interestingly revealed conversion of the main ligand of the androgen receptor
dihydrotestosterone (DHT) toward the inactive 5α-androstane3α,17β-diol (3α-Adiol). This activity was
further characterized through androgen receptor (AR) transactivation activity in an overexpressing system
and biochemically through kinetic enzyme turnover assays. Moreover, this activity allowed to develop a
novel screening lysate assay for substrates and inhibitors identification. However, no other promising
physiologically relevant substrates were revealed.
In the second part, the phenotypic changes upon DHRS7 silencing were investigated in endogenous cell
models by functional cancer assays, mass spectrometry and untargeted proteomics supported by cell
cycle analysis, immunofluorescence, real time qPCR and western blot. These results disproved the
modulation of the endogenous AR in the prostate cancer cell line LNCaP under DHRS7 depletion but
supported the hypothesis of DHRS7 having a tumor suppressor role with protein changes observed for
cell cycle, adhesion and migration relevant to the phenotype. Interestingly, protein changes involved in
mechanisms relevant for tumor biogenesis were observed.
In conclusion, the results presented in this thesis extend the knowledge about DHRS7 in vitro activity,
provide the characterization of an in vitro tool to test hypothesized substrates and inhibitors and suggest
further investigation toward androgen receptor independent mechanisms.
Advisors:Odermatt, Alex and Arand, Michael
Faculties and Departments:05 Faculty of Science > Departement Pharmazeutische Wissenschaften > Pharmazie > Molecular and Systems Toxicology (Odermatt)
UniBasel Contributors:Araya, Selene and Odermatt, Alex
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:12764
Thesis status:Complete
Bibsysno:Link to catalogue
Number of Pages:1 Online-Ressource (154 Seiten)
Language:English
Identification Number:
Last Modified:18 Oct 2018 04:30
Deposited On:17 Oct 2018 14:48

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