THE ROLE OF DOCOSAHEXAENOIC ACID IN NORMAL PROSTATE AND IMPLICATIONS IN TUMOR INITIATION AND PROGRESSION

Abstract

The type and amount of dietary lipids can differentially affect the prostate and promote the development of prostate cancer (PCa). The protective role initially attributed to polyunsaturated fatty acids (PUFAs) - eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) - in PCa has been questioned in recent studies. We have observed a variable action of DHA on the proliferation of non-tumorigenic prostate cells PNT1A and impairment to mitochondrial physiology, depending on the concentration. In this scenario, we will investigate, experimentally, the effects of docosahexaenoic acid on the histophysiology of the normal prostate and its role in the development and progression of prostate cancer. Two investigative approaches will be used, in vivo and in vitro. In the in vivo study (9 groups, n = 10 per group), we will analyze the effects of dietary supplementation of healthy mice (8 months old) with DHA / EPA enriched ration in short (1 month) and long term (3 months ), on the ventral prostate and the impact of this supplementation on the development of PCa in transgenic mice for this adenocarcinoma (TRAMP). Therefore, the metabolic profile of the animals will be evaluated; the prostatic tissue response based on cell proliferation, apoptosis and incidence of pathological lesions; the inflammatory response, based on the serum and intra-titer levels of proinflammatory factors (interleukins 6 and 1², tumor necrosis factor ±, cyclooxygenase 2) and the gene expression (qRT-PCR Array) and protein (Western blottiing and Immunohistochemistry) (± and ² estrogen receptor, peroxisome proliferation ³ receptor, retinoid receptor X, and ±- and ß-liver X receptors). In the in vitro study, human prostate cell lines with distinct characteristics, i.e. (PNT1A), androgen-responsive tumor cells (22rv1) and non-responsive to androgen PC3, will be used to assess whether there are inherent metabolic signatures of each tumor stage and whether DHA is able to modulate it. The gene expression of aforementioned nuclear receptors involved with the metabolism and oncogenic potential will be mapped for each lineage, by RT-PCR array, and validated by western blotting and cytolocalization by confocal microscopy. The metabolomic profile (LC-ESI-QTOF-MS) of each cell line will be evaluated and compared with data about expression of nuclear receptors and mitochondrial signatures, these latter investigated based on analysis of function (MitoSOX), morphology (MitoTracker and Electron Transmission Electron Microscopy), and mitochondrial dynamics (Mfn1 and Drp1). Then we will perform dose response study of DHA and examine its ability to alter these metabolic signatures and mitochondrial parameters. We will investigate the cross-road of these alterations with the AKT, mTOR, ERK1 / 2 and PTEN survival pathways. This project will improve the knowledge about the mechanism by which DHA and EPA affect cell proliferation and death and their interactions with metabolism, mitochondrial physiology, and regulation by nuclear receptors and provide further insights into the action of these fatty acids in the prevention and treatment of prostate cancer. (AU)