Browsing by Author "Socorro, Silvia"
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- Glutaminolysis is a metabolic route essential for survival and growth of prostate cancer cells and a target of 5 alpha-dihydrotestosterone regulationPublication . Cardoso, Henrique J.; Figueira, Marilia, I; Vaz, Catia V.; Carvalho, Tiago M. A.; Bras, Luis A.; Madureira, Patricia; Oliveira, Paulo J.; Sardao, Vilma A.; Socorro, SilviaPurpose Resistance to androgen-deprivation therapies and progression to so-called castrate-resistant prostate cancer (CRPC) remain challenges in prostate cancer (PCa) management and treatment. Among other alterations, CRPC has been associated with metabolic reprogramming driven by androgens. Here, we investigated the role of androgens in regulating glutaminolysis in PCa cells and determined the relevance of this metabolic route in controlling the survival and growth of androgen-sensitive (LNCaP) and CRPC (DU145 and PC3) cells. Methods PCa cells (LNCaP, DU145 and PC3) and 3-month old rats were treated with 5 alpha-dihydrotestosterone (DHT). Alternatively, LNCaP cells were exposed to the glutaminase inhibitor BPTES, alone or in combination with the anti-androgen bicalutamide. Biochemical, Western blot and extracellular flux assays were used to evaluate the viability, proliferation, migration and metabolism of PCa cells in response to DHT treatment or glutaminase inhibition. Results We found that DHT up-regulated the expression of the glutamine transporter ASCT2 and glutaminase, both in vitro in LNCaP cells and in vivo in rat prostate cells. BPTES diminished the viability and migration of PCa cells, while increasing caspase-3 activity. CRPC cells were found to be more dependent on glutamine and more sensitive to glutaminase inhibition. BPTES and bicalutamide co-treatment had an additive effect on suppressing LNCaP cell viability. Finally, we found that inhibition of glutaminolysis differentially affected glycolysis and lipid metabolism in both androgen-sensitive and CRPC cells. Conclusion Our data reveal glutaminolysis as a central metabolic route controlling PCa cell fate and highlight the relevance of targeting glutaminase for CRPC treatment.
- Sperm parameters and epididymis function in transgenic rats overexpressing the Ca-2-binding protein regucalcin: a hidden role for Ca-2 in sperm maturation?Publication . Correia, S.; Oliveira, P. F.; Guerreiro, P. M.; Lopes, G.; Alves, M. G.; Canario, Adelino; Cavaco, J. E.; Socorro, SilviaSperm undergo maturation acquiring progressive motility and the ability to fertilize oocytes through exposure to the components of the epididymal fluid (EF). Although the establishment of a calcium (Ca-2) gradient along the epididymis has been described, its direct effects on epididymal function remain poorly explored. Regucalcin (RGN) is a Ca-2-binding protein, regulating the activity of Ca-2-channels and Ca-2-ATPase, for which a role in male reproductive function has been suggested. This study aimed at comparing the morphology, assessed by histological analysis, and function of epididymis, by analysis of sperm parameters, antioxidant potential and Ca-2 fluxes, between transgenic rats overexpressing RGN (Tg-RGN) and their wild-type littermates. Tg-RGN animals displayed an altered morphology of epididymis and lower sperm counts and motility. Tissue incubation with Ca-45(2) showed also that epididymis of Tg-RGN displayed a diminished rate of Ca-2-influx, indicating unbalanced Ca-2 concentrations in the epididymal lumen. Sperm viability and the frequency of normal sperm, determined by the one-step eosin-nigrosin staining technique and the Diff-Quik staining method, respectively, were higher in Tg-RGN. Moreover, sperm of Tg-RGN rats showed a diminished incidence of tail defects. Western blot analysis demonstrated the presence of RGN in EF as well as its higher expression in the corpus region. The results presented herein demonstrated the importance of maintaining Ca-2-levels in the epididymal lumen and suggest a role for RGN in sperm maturation. Overall, a new insight into the molecular mechanisms driving epididymal sperm maturation was obtained, which could be relevant to development of better approaches in male infertility treatment and contraception.