Identifying Mediators of Androgen-independent Prostate Cancer Using Mass Spectrometry-based Proteomics
Year: 2014
Type: dissertation
Abstract: Androgen-deprivation remains the principal therapy for advanced and metastatic prostate cancers. However, some cancer cells are able to survive this treatment and transform themselves to a more aggressive androgen-independent prostate cancer (AIPC). An understanding of the molecular alterations that occur during the progression to androgen-independence is of utmost importance in order to generate effective targeted therapies. Using two different in vitro approaches coupled to high through-put mass spectrometry, we were able to identify numerous potential mediators of AIPC and aggressive prostate cancer. Our first approach using an in vitro cell line model of androgen-independence allowed us to identify enzymes of the ketogenic pathway as elevated in cases of aggressive prostate cancer. Specifically, ACAT1, an enzyme in this pathway, was further validated and shown to be substantially elevated in clinical cases of castration-resistant metastatic prostate cancer. In addition, ACAT1 was found to be an independent tissue-based prognostic marker of biochemical recurrence-free survival. In our second approach we compared the secreted proteomes of androgen independent cell lines (PC3, DU145, PPC1, LNCaP-SF, 22Rv1) to androgen-dependent (LNCaP, VCaP) and normal prostate epithelial (RWPE) cell lines. Of the over 3000 proteins identified in the secretomes, we found more than 100 proteins that were differentially secreted in the androgen independent cell lines. Of these, Protein S (PROS1) was elevated in the secretomes of all the AIPC cell lines and was not detected in the normal or androgen-dependent prostate cancer cell lines. Next, using RT-PCR and immunohistochemistry, we observed significantly higher tissue expression levels of PROS1 in localized high-grade and castrate-resistant metastatic prostate cancer samples compared to normal and low-grade prostate cancer, further indicating its importance in prostate cancer progression. Finally, functional validation revealed that PROS1 increases cell proliferation, migration and viability and thus may play a direct role on prostate cancer biology.Taken together, the results of this research will help in not only increasing the understanding of key molecular alterations and mechanisms by which prostate cancer cells can utilize to gain androgen-independence, and more importantly, aid in the development of new targeted therapies by potentially focusing on blocking or altering specific critical signalling cascades.
Source: TSpace (University of Toronto)
Author: Punit Saraon
Language: English
Subfield: Cancer Research
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2516080218