Assessing the Effects of Vitamin D as a Regulator of Androgen Intracrinology in Prostate Cancer using Mass Spectrometry Imaging

  • Karl Smith

Student thesis: Doctoral Thesis

Abstract

Castrate resistant prostate cancer (CRPC) relies on the supply of potentandrogens such as dihydrotestosterone (DHT) from intratumoral conversionfrom the precursor dehydroepiandrosterone (DHEA) for growth. Vitamin D hasbeen proposed as a chemotherapeutic agent by way of vitamin D receptor(VDR) activation. The mechanistic enzymes of the intracrine pathway areinfluenced by VDR activation and thus can have a beneficial effect of theoutcome of androgen synthesis, by reducing the active androgens produced.In this thesis, I aimed to explore the metabolic outcomes of vitamin D treatmentupon a CRPC translation model, by assessing the androgen intracrineconversions using mass spectrometry-based techniques and genetic changes.Employing an in vitro based assay, effects of vitamin D treatment wereassessed for metabolic changes within the CRPC steroid pathway, using a semiquantitative method. Further evaluation of key metabolic gene changes wasalso undertaken. Findings confirm that vitamin D treatment decreased the levelsof potent androgens, with increased hydroxylation, linked to the upregulation ofthe gene CYP3A4.An in vivo prostate cancer xenograft was also evaluated for vitamin D treatmentupon castration and DHEA introduction. Spatial distribution of endogenousandrogens in prostatic cancerous tissue were assessed using massspectrometry imaging. A method of chemical derivatisation for neutralendogenous androgens was developed using the ImagePrep device, enhancingionisation efficiency for on-tissue analysis. Biological assays were alsoemployed to determine any effects exhibited by the vitamin D treatment, such agene expression analysis and total androgen quantitation. Vitamin D was foundto induce changes in slowing growth and lowering levels of potent androgens.To further explore vitamin D treatment assay capabilities, a novel chemicalderivatisation method for mass spectrometry imaging was developed byscreening numerous reagents for off and on-tissue analysis. Ion efficiency wasenhanced for on-tissue endogenous vitamin D metabolites with successfulimaging of derivatised 25-(OH)-D2 and 1,25-(OH)2-D3 in mouse kidneys.
Date of AwardMar 2020
Original languageEnglish
SupervisorDiego Cobice (Supervisor) & Paul Thompson (Supervisor)

Keywords

  • Mass spectrometry imaging
  • On-tissue chemical derivatisation
  • Castrate resistance Prostate cancer
  • Metabolism
  • Androgen intracrinology
  • Vitamin D

Cite this

Assessing the Effects of Vitamin D as a Regulator of Androgen Intracrinology in Prostate Cancer using Mass Spectrometry Imaging
Smith, K. (Author). Mar 2020

Student thesis: Doctoral Thesis