Câncer de próstata e estresse oxidativo: análise da expressão e do potencial terapêutico da enzima sulfiredoxina

Author(s)

Caroline Nascimento Barquilha

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2019-04-23

Examining board members

Sérgio Luis Felisbino; Sabrina Thalita dos Reis Faria; Wagner José Fávaro

• Advisor: Sérgio Luis Felisbino

Abstract

Prostate cancer (PCa) is the second most frequent and the second highest rate of mortality among men. Despite the advances in cancer therapies, it is still necessary to search for new therapeutic targets, especially for the metastatic stages of PCa that are resistant to the available treatments. Considering the important role of antioxidant pathways in the carcinogenesis and survival of tumor cells, our hypothesis was that oxidative stress-related genes would be potential targets. Thus, our aim was to identify and validate, among the genes of antioxidant pathways, a therapeutic target for PCa, as well to evaluate how different factors modulate its gene and protein expression. First, we analyzed transcriptome data (RNAseq) from prostatic tumors of transgenic Pb-Cre4;Ptenf/f mice in search of genes differentially expressed in PCa (up-regulation) and, among the genes related to oxidative stress, we selected the sulfiredoxin enzyme (SRXN1) gene for functional validations. By the transcriptome, we observed a gene overexpression of SRXN1 in PCa, which was reflected in the also increased protein expression of this enzyme, observed by immunohistochemistry in slices of prostate tumors from mice. Analyses in previously published human PCa database also confirmed the up-regulation of SRXN1, mainly in patients with worst prognosis, and lower disease/progression-free survival curve . Subsequently, we confirmed the increased expression of SRXN1 in our own samples of human prostate tumors (tissue microarray), which were associated with patients with poor prognosis and lower survival rates. We also performed in vitro assays to analyze the SRXN1 expression pattern in normal (RWPE-1 and PNT-2) and cancerous (LNCaP and PC-3) prostate cell lines, as well the silencing of the mRNA to SRXN1 in LNCaP tumor cells. In addition, we exposed the prostate cells to testosterone, flutamide, fibronectin and H2O2 to better understand the modulation of SRXN1 protein and gene expression in PCa. In vitro analyses showed that PCa cell lines express more SRXN1 than normals and the inhibition of the mRNA to SRXN1 decreases the viability of tumor cells. Furthermore, it was observed that protein and gene expression of this enzyme is differentially modulated by testosterone, flutamide, fibronectin and H2O2 in prostatic cell lines, which have different mechanisms of stress response and different metabolisms. Thus, our work points the SRXN1 enzyme as a potential therapeutic target for metastatic PCa. Within the context of the precision medicine, our results suggest that the use of selective inhibitors for SRXN1 may be an effective strategy to adjuvant treatment of the subset of patients with PCa that has overexpression of this enzyme. It is still necessary a better understanding of how SRXN1 expression is regulated in the different phases of PCa progression to the development of new therapeutic approaches using inhibitors to SRXN1 (AU)

• FAPESP's process: 16/25945-6 - Prostate cancer and oxidative stress: analysis of expression and therapeutic potential of the enzyme sulfiredoxin
• Grantee: Caroline Nascimento Barquilha
• Support Opportunities: Scholarships in Brazil - Master