Understanding Prostate Cancer

Prostate cancer is the second most common diagnosed cancer and the third mostcommon cause of death related to cancer among men in developed countries. Severalepidemiological studies, prospective cohort studies and animal tumour models state aninverse relationship between selenium status and cancer incidence. Semethylselenocysteine(SeMSC), present in garlic, onions, leeks and broccoli, has beenshown to be the most effective anti-carcinogenic selenium form in animal models. The aimof the work presented in this thesis was to investigate the influence of seleniumcompounds (Se-methylselenocysteine and selenomethionine) on prostate cancerprogression and metastasis using various human cell lines (LNCaP, DU145 and PC3).Standard 2D gel and SILAC (stable isotope labelling with amino acids in cell culture)proteomics were used, in combination with mass spectrometry, to identify seleniumresponsiveproteins. Resulting proteins were clustered and modelled around the prostatecancer signalling pathway. IMPDH2, GPI, EZR and RGS10 were validated by western blot,while PDIA3 and DDX5 showed a selenium response under serum depleted conditions.Some proteins require more scrutinizing (galectin-1, XRCC5, TAGLN2, DDX5 and FLT) asconflicting results were obtained during validation. Preliminary analysis using 2D gelproteomics revealed galectin-1 to be selenium-responsive in PNT1A cells, although thiscould not be confirmed by Western blot or an in-house ELISA. Previously, it has beenshown that SeMSC decreased the expression of collagen I and increased that of collagenIV and collagen VI. A LNCaP 3D gel suspension model was developed to allow furtherinvestigation of extracellular matrix components using fluorescence microscopy. Inaddition, the effect of selenium exposure on the migration and invasion of PC3 cells wasinvestigated using a transwell kinetic assay and revealed a dose response increase,especially under low baseline selenium concentrations. In order to optimize futureselenium in vitro projects the dynamics of several selenium biomarkers were investigatedusing different conditions, enabling better comparison between cell lines and/or seleniumcompounds.