Variable effects of periprostatic adipose tissue on prostate cancer cells: Role of adipose tissue lipid composition and cancer cells related factors.

BACKGROUND: Periprostatic adipose tissue (PPAT) is likely to modulate prostate cancer (PCa) progression. We analyzed the variations in the effect of PPAT on cancer cells, according to its fatty acid (FA) composition and tumor characteristics. METHODS: The expression of markers of aggressiveness Ki67 and Zeb1, and epigenetic marks that could be modified during PCa progression, was analyzed by immunohistochemistry on a tissue-micro-array containing 59 pT3 PCa, including intra-prostatic areas and extra-prostatic foci in contact with PPAT belonging to the same tumor. In addition, we cocultivated PC3 and LNCaP cell lines with PPAT, which were then analyzed for FA composition. RESULTS: Although the contact between PPAT and cancer cells led overall to an increase in Ki67 and Zeb1, and a decrease in the epigenetic marks 5MC, 5HMC, and H3K27ac, these effects were highly heterogeneous. Increased proliferation in extra-prostatic areas was associated with the international society of uropathology score. PC3 and LNCaP cocultures with PPAT led to increased Ki67, Zeb1 and H3K27me3, but only for PPAT associated with aggressive PCa. PC3 proliferation was correlated with high 20.2 n-6 and low 20.5n-3 in PPAT. CONCLUSIONS: These results suggest that the effects of PPAT on cancer cells may depend on both PCa characteristics and PPAT composition, and could lead to propose nutritional supplementation.

Development of a High-Performance Thin-Layer Chromatography Method for the Quantification of Alkyl Glycerolipids and Alkenyl Glycerolipids from Shark and Chimera Oils and Tissues.

Ether lipids are composed of alkyl lipids with an ether bond at the sn-1 position of a glycerol backbone and alkenyl lipids, which possess a vinyl ether bond at the sn-1 position of the glycerol. These ether glycerolipids are present either as polar glycerophospholipids or neutral glycerolipids. Before studying the biological role of molecular species of ether glycerolipids, there is a need to separate and quantify total alkyl and alkenyl glycerolipids from biological samples in order to determine any variation depending on tissue or physiopathological conditions. Here, we detail the development of the first high-performance thin-layer chromatography method for the quantification of total alkyl and alkenyl glycerolipids thanks to the separation of their corresponding alkyl and alkenyl glycerols. This method starts with a reduction of all lipids after extraction, resulting in the reduction of neutral and polar ether glycerolipids into alkyl and alkenyl glycerols, followed by an appropriate purification and, finally, the linearly ascending development of alkyl and alkenyl glycerols on high-performance thin-layer chromatography plates, staining, carbonization and densitometric analysis. Calibration curves were obtained with commercial alkyl and alkenyl glycerol standards, enabling the quantification of alkyl and alkenyl glycerols in samples and thus directly obtaining the quantity of alkyl and alkenyl lipids present in the samples. Interestingly, we found a differential quantity of these lipids in shark liver oil compared to chimera. We quantified alkyl and alkenyl glycerolipids in periprostatic adipose tissues from human prostate cancer and showed the feasibility of this method in other biological matrices (muscle, tumor).

Hypoxia Promotes Prostate Cancer Aggressiveness by Upregulating EMT-Activator Zeb1 and SK3 Channel Expression.

Hypoxia is a well-established feature of prostate cancer (PCa) and is associated with disease aggressiveness. The hypoxic microenvironment initiates multiple adaptive responses including epithelial-to-mesenchymal transition (EMT) and a remodeling of calcium homeostasis involved in cancer progression. In the present study, we identified a new hypoxia signaling pathway with a positive feedback loop between the EMT transcription factor Zeb1 and SK3, a Ca2+-activated K+ channel, which leads to amplifying store-operated Ca2+ entry. Zeb1 and SK3 channel were strongly upregulated by hypoxia both in vitro and ex vivo in organotypic cultures of human PCa. Taking into account the sensitivity of the SK3 channel to the membrane lipid composition, we identified lipids such as Ohmline (an alkyl ether lipid and SK3 inhibitor), linoleic acid (LA) and eicosapentaenoic acid (EPA) (fatty acids associated with indolent PCa), which were able to completely abrogate the hypoxia-induced changes in Zeb1 expression. Ultimately, better understanding of this new hypoxia-induced EMT pathway may allow to develop adjuvant therapeutic strategies, in order to control PCa aggressiveness and improve treatment outcomes.

A Novel Calcium-Mediated EMT Pathway Controlled by Lipids: An Opportunity for Prostate Cancer Adjuvant Therapy.

The composition of periprostatic adipose tissue (PPAT) has been shown to play a role in prostate cancer (PCa) progression. We recently reported an inverse association between PCa aggressiveness and elevated PPAT linoleic acid (LA) and eicosapentaenoic acid (EPA) content. In the present study, we identified a new signaling pathway with a positive feedback loop between the epithelial-to-mesenchymal transition (EMT) transcription factor Zeb1 and the Ca2+-activated K+ channel SK3, which leads to an amplification of Ca2+ entry and cellular migration. Using in vitro experiments and ex vivo cultures of human PCa slices, we demonstrated that LA and EPA exert anticancer effects, by modulating Ca2+ entry, which was involved in Zeb1 regulation and cancer cellular migration. This functional approach using human prostate tumors highlights the clinical relevance of our observations, and may allow us to consider the possibility of targeting cancer spread by altering the lipid microenvironment.

4TM-TRPM8 channels are new gatekeepers of the ER-mitochondria Ca2+ transfer.

Calcium (Ca2+) release from the endoplasmic reticulum plays an important role in many cell-fate defining cellular processes. Traditionally, this Ca2+ release was associated with the ER Ca2+ release channels, inositol 1,4,5­triphosphate receptor (IP3R) and ryanodine receptor (RyR). Lately, however, other calcium conductances have been found to be intracellularly localized and to participate in cell fate regulation. Nonetheless, molecular identity and functional properties of the ER Ca2+ release mechanisms associated with multiple diseases, e.g. prostate cancer, remain unknown. Here we identify a new family of transient receptor potential melastatine 8 (TRPM8) channel isoforms as functional ER Ca2+ release channels expressed in mitochondria-associated ER membranes (MAMs). These TRPM8 isoforms exhibit an unconventional structure with 4 transmembrane domains (TMs) instead of 6 TMs characteristic of the TRP channel archetype. We show that these 4TM-TRPM8 isoforms form functional channels in the ER and participate in regulation of the steady-state Ca2+ concentration ([Ca2+]) in mitochondria and the ER. Thus, our study identifies 4TM-TRPM8 isoforms as ER Ca2+ release mechanism distinct from classical Ca2+ release channels.