However the optimal working concentration
However, the optimal working concentration of NPY in the periphery is debatable. NPY bimodally stimulated endothelial cell proliferation at 10M and 10M, and at 10M, NPY significantly increased the proliferation of SVEC4–10 MLN 9708 (Movafagh et al., 2006). Direct anti-proliferative and pro-apoptotic activity induced by 10M NPY was observed in ovarian follicular cells (Sirotkin et al., 2015). Given the differences in these reports, we first determined an appropriate NPY concentration using CCK-8 assays and confirmed our results using qPCR. In fact, it has been shown that neurons in the central nervous system (CNS) secrete NPY to maintain concentrations of 10M under basal conditions (Husum et al., 2002), and the normal range of plasma NPY is 10–10M42 (Panuccio et al., 2007). Thus, the concentration we selected is close to physiological levels and could improve BMSC activity.
In our study, we observed that pretreatment of BMSCs with PD160170, a Y1 receptor antagonist, blocked the proliferative and protective effects of NPY treatment, suggesting a transcriptional regulation that might be mediated by activation of the Y1 receptor. However, other reports with similar data did not specify the type of NPY receptor studied. NPY signaling via the Y1 receptor has previously been implicated in the regulation of BMSCs, and Y1R is the only NPY receptor expressed by BMSCs (Lee et al., 2010). Notwithstanding the controversies regarding whether the Y5 receptor is important for BMSC proliferation (Igura et al., 2011), several investigators have demonstrated an NPY/Y1R ligand-receptor interaction in the proliferation of adipocyte precursor cells (Yang et al., 2008) as well as a role for Y1R, Y2R, and Y5R in endothelial cell proliferation (Movafagh et al., 2006).
Recently, our preliminary findings showed that the Wnt/β-catenin signaling pathway is an important regulator of BMSC growth, differentiation, and apoptotic death (Liu et al., 2016; Fu et al., 2015; Mei et al., 2013). In this study, we demonstrated that NPY prolonged the activation of the Wnt/β-catenin signaling pathway in BMSCs during proliferation and under conditions of serum deprivation-induced apoptosis. However, this study fails to directly link Wnt signaling with NPY-Y1 signaling, which requires follow-up studies. Such pleiotropic effects may be related to differences in the timing of Wnt signaling with respect to the state of the cell\'s fate or to changes in other interacting signaling pathways during development. We observed that NPY treatment of BMSCs up-regulated the protein expression of p-GSK-3β, β-catenin and c-myc, which were all decreased in the presence of DKK1 and a Y1R antagonist. The Wnt/β-catenin pathway affects cellular functions by activating GSK-3β, which regulates the levels of β-catenin and its translocation into the nucleus. Without Wnt, the β-catenin levels are maintained at a steady state. Several previous reports have suggested a critical role of Wnt and β-catenin in mediating cell proliferation and the survival of osteoblasts (Westendorf et al., 2004) and neural progenitor cells (Holowacz et al., 2011).
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Conflicts of interest
Acknowledgments and funding This work was funded by National Natural Science Foundation of China (No. 81171723 and No. 81572165) and Guangdong Provincial Science and Technology Plan Project (No. 2016B090913004).
Introduction Adenoid cystic carcinoma (ACC) are rare and highly aggressive neoplasms of salivary glands and the breast. ACC of the salivary gland represents approximately 22% of all salivary gland malignancies; these tumors are slow-growing and have a high potential for local recurrence (Hitre et al., 2013; Duberge et al., 2012; Hotte et al., 2005). The treatment of choice for ACC is surgical resection followed by postoperative radiotherapy. While the effectiveness of chemotherapy in treating ACC has been extensively studied, outcomes remain poor (de Haan et al., 1992; Licitra et al., 1991; Lagha et al., 2012). Following treatment, 29% to 40% of patients with ACC experience a disease-free survival of 10years (Fordice et al., 1999). The majority of deaths from salivary ACC are due to local recurrence and distant metastasis and are associated with resistance to conventional therapy. Due to the low incidence of ACC in the general population, the molecular events underlying tumor progression, metastasis, and resistance to treatment are underexplored; as such, this presents a major roadblock for understanding the biology of ACC and for expanding ACC therapy beyond the limited number of effective treatments (Liu et al., 2015a).