Apoptotic Effects of Dietary and Synthetic Sphingolipids in Androgen-Independent (PC-3) Prostate Cancer Cells

UPLC-ESI-Q-TOF-MS/MS analysis of anticancer fractions from Ophiocordyceps xuefengensis and Ophiocordyceps sinensis

Ophiocordyceps xuefengensis (O. xuefengensis), a new species of caterpillar fungus, has been identified as the sister taxon of Ophiocordyceps sinensis (O. sinensis). The aims of the present study are to evaluate the anticancer activity and to qualitatively analyze the potential bioactive chemical constituents of O. xuefengensis and O. sinensis, comparatively. An MTT assay was used to evaluate the in vitro anticancer activities of different fractions from O. xuefengensis and O. sinensis. The results show that ethyl acetate fractions of O. xuefengensis and O. sinensis have significant in vitro anticancer activity. These two bioactive fractions were analyzed by ultra-performance liquid chromatography-electrospray ionization with quadrupole-time of flight tandem mass spectrometry technology. A total of 82 compounds and 101 compounds were identified or tentatively characterized in the bioactive fractions of O. xuefengensis and O. sinensis, respectively. Among these compounds, 68 existed in both O. xuefengensis and O. sinensis. A total of 67 compounds were reported in O. xuefengensis and 8 compounds were reported in caterpillar fungus for the first time. This is the first detailed comparative analysis of the in vitro anticancer activity and chemical ingredients between O. xuefengensis and O. sinensis. The application of this work will provide reliable fundamental pharmacological substances for the use of O. xuefengensis by Yao people.

Hypermethylation contributes to down-regulation of lysosomal β-hexosaminidase α subunit in prostate cancer cells

β-Hexosaminidase, involved in degradation of glycoproteins and glycosphingolipids, is altered in several tumours leading to enhanced migration capacity. To date, the expression of the β-hexosaminidase isoenzymes in prostate cancer cells has not been elucidated. By using PC3, LNCaP, DUCaP, MDAPCa 2b, and hyperplasic prostate (BPH-1) cell lines, we analysed the β-hexosaminidase activity in each cell line and determined β-hexosaminidase α subunit gene expression in PC3, LNCaP, and BPH-1. We then investigated the methylation status of the gene promoter and determined the cellular responses of PC3 and LNCaP after transfection with β-hexosaminidase α subunit. We found that each prostate cancer cell line had a decrease in total hexosaminidase activity and that the lack of hexosaminidase A activity, observed in PC3 and LNCaP cells, was associated with mRNA disappearance. The HEXA promoter region in LNCaP and PC3 cell lines had methylated CpG islands, as confirmed by 5'-Aza-2'-deoxycitidine treatment, in PC3 cells, used as cell cancer model. We also tested, the involvement of hexosaminidase A in the migration capacity by migration assay using Hex α subunit-transfected PC3. Finally, we found that, after Hex α subunit transfection, both PC3 and LNCaP were less susceptible to exogenous ceramide treatment. Results indicate a likely contribution of the lysosomal enzyme to the acquisition of cancerous features.

C6-ceramide in combination with transforming growth factor-β enhances Treg cell differentiation and stable FoxP3 expression in vitro and in vivo

Ceramides, sphingosine-based lipid molecules, are generated mainly from the hydrolysis of sphingomyelin and play pivotal roles in biological processes including cell growth, differentiation, and inflammation. In this study, we investigated the effect of exogenous ceramides on the differentiation of regulatory T (Treg) cells and expression of FoxP3 gene in Treg cells. A cell-permeable C6-ceramide (C6) was capable of upregulating Treg cell differentiation when acting together with transforming growth factor-beta (TGF-β), and this induction was independent of T-cell receptor (TCR) and CD28 strength. Additionally, TGF-β/C6 treatment sustained the expression of FoxP3 gene in Treg cells, as the percentages of FoxP3(+) Treg cells in the TGF-β/C6-treated group remained high for prolonged periods compared to those in the group treated with TGF-β alone. Furthermore, C8-ceramide was also capable of sustaining Treg cell populations and FoxP3 expression, whereas C2-, C16-, and C24-ceramides did not. Importantly, adoptive transfer of the TGF-β/C6-induced Treg cells into syngenic mice showed that TGF-β/C6-induced Treg cells maintained their FoxP3 expression in vivo significantly longer periods than the TGF-β-induced Treg cells. Taken together, our findings indicate that C6 can be utilized to increase Treg cell populations and also to sustain their FoxP3 expression in the treatment of autoimmune diseases or graft rejection.