BackgroundWnt-11 is a secreted protein that modulates cell growth, differentiation and morphogenesis during development. We previously reported that Wnt-11 expression is elevated in hormone-independent prostate cancer and that the progression of prostate cancer from androgen-dependent to androgen-independent proliferation correlates with a loss of mutual inhibition between Wnt-11- and androgen receptor-dependent signals. However, the prevalence of increased expression of Wnt-11 in patient tumours and the functions of Wnt-11 in prostate cancer cells were not known.ResultsWnt-11 protein levels in prostate tumours were determined by immunohistochemical analysis of prostate tumour tissue arrays. Wnt-11 protein was elevated in 77/117 of tumours when compared with 27 benign prostatic hypertrophy specimens and was present in 4/4 bone metastases. In addition, there was a positive correlation between Wnt-11 expression and PSA levels above 10 ng/ml. Androgen-depleted LNCaP prostate cancer cells form neurites and express genes associated with neuroendocrine-like differentiation (NED), a feature of prostate tumours that have a poor prognosis. Since androgen-depletion increases expression of Wnt-11, we examined the role of Wnt-11 in NED. Ectopic expression of Wnt-11 induced expression of NSE and ASCL1, which are markers of NED, and this was prevented by inhibitors of cyclic AMP-dependent protein kinase, consistent with the known role of this kinase in NED. In contrast, Wnt-11 did not induce NSE expression in RWPE-1 cells, which are derived from benign prostate, suggesting that the role of Wnt-11 in NED is specific to prostate cancer. In addition, silencing of Wnt-11 expression in androgen-depleted LNCaP cells prevented NED and resulted in apoptosis. Silencing of Wnt-11 gene expression in androgen-independent PC3 cells also reduced expression of NSE and increased apoptosis. Finally, silencing of Wnt-11 reduced PC3 cell migration and ectopic expression of Wnt-11 promoted LNCaP cell invasion.ConclusionsThese observations suggest that the increased level of Wnt-11 found in prostate cancer contributes to tumour progression by promoting NED, tumour cell survival and cell migration/invasion, and may provide an opportunity for novel therapy in prostate cancer.

Retinoic acid and Wnt/β‐catenin signals play important roles during neuronal differentiation but less is known about noncanonical Wnt signals in this context. We examined retinoic acid and Wnt signaling in two human embryonal carcinoma cell lines, NTERA‐2 (clone D1), which undergoes neuronal differentiation in response to retinoic acid, and 2102Ep, which does not. Retinoic acid treatment inhibited β‐catenin/Tcf activity in NTERA‐2 cells but not in 2102Ep cells. Inhibition occurred downstream of β‐catenin but did not involve competition between retinoic acid receptors and β‐catenin for binding to p300 or Tcf‐4. Ectopic expression of FZD1 partially restored inhibition in 2102Ep cells, suggesting the involvement of Wnt ligands. Retinoic acid treatment of NTERA‐2 cells induced the expression of Wnt‐4 and Wnt‐11, both of which were able to inhibit β‐catenin/Tcf activity. Wnt‐4 and Wnt‐11 were found at cell borders in islands of cells that expressed OCT4 and GFAP and were predominantly negative for Nestin, PAX6, and GATA6. Gene silencing of Wnt‐4, but not Wnt‐11, reduced retinoic acid downregulation of OCT4 and Nanog and upregulation of PAX6, ASCL1, HOXC5, and NEUROD1, suggesting that Wnt‐4 promotes early neuronal differentiation. Gene expression analysis of NTERA‐2 cells stably overexpressing Wnt‐11 suggested that Wnt‐11 potentiates retinoic acid induction of early neurogenesis. Consistent with this, overexpression of Wnt‐11 maintained a population of proliferating progenitor cells in cultures treated with retinoic acid for several weeks. These observations highlight the distinct roles of two noncanonical Wnts during the early stages of retinoic acid‐induced neuronal differentiation. STEM CELLS 2011;29:141–153

This study investigates the ability of a polyphenolic extract obtained from a wine lees by-product to modulate zebrafish lipid metabolism. Lees from a Spanish winery were collected and the polyphenolic extract was chemically characterised in terms of antioxidant capacity, total phenolic content and the individual main phenolic compounds. The effects of the extract on lipid metabolism were evaluated using a zebrafish animal model. Lees are rich in polyphenols (42.33 mg gallic acid equivalent per g dry matter) with high antioxidant capacity (56.04 mg Trolox equivalent per g dry matter), rutin and quercetin being their main identified polyphenols. The biological effects of lees extract included (i) a reduction in zebrafish embryos' fat reserve (40%), (ii) changes in the expression of lipid metabolism key genes, (iii) remodelling of the fatty acid content in phospholipid and triglyceride fractions of zebrafish embryos and (iv) reduction in the trans fatty acid content. On the whole, wine lees polyphenolic extract was effective at modulating zebrafish lipid metabolism evidencing remodelling effects and antioxidant properties that can be further developed for food innovation.

Zebrafish have been traditionally used in ecotoxicology and developmental biology. However, due to the advances in available methodologies and the similitude with mammals, it has been increasingly used in other fields. One of the most recent fields using zebrafish is food research, being the focus of this review. Most relevant and recent publications including food component toxicity and key metabolic effects together with effectiveness on some zebrafish disease models have been reviewed. This model is a good intermediate tool between in vitro and rodent models, because it provides information from a complete organism in a fast and cost-effective manner. Definitely, in the near future, we will see this model being used by the ingredient suppliers and scientists in order to show the potential impact on health of several compounds.

Resveratrol, a polyphenolic phytoalexin found in many plants, has been reported to have antiobesogenic effects in several animal and in vitro models. Zebrafish present several technical advantages that place them at an interesting, halfway point between in vitro and rodent models. The aim of the present work was to evaluate the metabolization of resveratrol and its glucoside (piceid) in zebrafish and their ability to induce the consumption of fat reserve in zebrafish larvae. Resveratrol and piceid were both able to reduce yolk sac fat content depending on the dose tested. Furthermore, resveratrol showed a potent and rapid action, whereas piceid needed more time and higher doses to be as effective as resveratrol. In accordance with other animal models and humans, the principal metabolites found in zebrafish larvae were monoglucoronide and monosulfate forms of resveratrol. In conclusion, zebrafish are a potentially excellent animal model for polyphenol research as they present several advantageous characteristics for efficacy screening and metabolomic studies before rodents.