Bioactive sphingolipids are potent intracellular signaling molecules having profound effects on cell death, growth, and differentiation. Pharmacologic manipulation of sphingolipid levels could have a significant effect on the induction of apoptosis by anticancer agents, and thus, improve treatment efficacy. We observed that gemcitabine cannot completely kill AsPc1 and Panc1 human pancreatic cancer cells in culture; even at high concentrations of gemcitabine, 30% to 40% of the cells remain viable. By adding sphingomyelin to the culture medium, gemcitabineinduced cell death increased synergistically to >90%. Panc1 cells that survived high concentrations of gemcitabine had an increase in β-galactosidase activity, a marker of senescence. The inclusion of sphingomyelin with gemcitabine reduced β-galactosidase activity, as compared with cells treated with gemcitabine alone. Expression of p21 waf1/cip1 in both cell lines exposed to sphingomyelin, gemcitabine, and gemcitabine + sphingomyelin varied relative to the untreated group. C 8 -ceramide induced both cell death and senescence in a dose-dependent manner. These results indicate that gemcitabine induces senescence in pancreatic cancer cells and that sphingomyelin-enhanced chemosensitivity is achieved through reducing the induction of senescence by redirecting the cell to enter the apoptotic pathway. Ceramide levels seem to be critical to this decision, with cell cycle progression being uninhibited at low ceramide levels, senescence induced at moderate levels, and apoptosis initiated at high levels. Our results provide further evidence that targeting the sphingolipid metabolism is a means of enhancing the efficacy of chemotherapeutic agents. (Mol Cancer Res 2009;7(6):890-6)

Contact with the urticating setae from the abdomen of adult females of the neo-tropical moth Hylesia metabus gives rise to an urticating dermatitis, characterized by intense pruritus, generalized malaise and occasionally ocular lesions (lepidopterism). The setae contain a pro-inflammatory glycosylated protease homologous to other S1A serine proteases of insects. Deglycosylation with PNGase F in the presence of a buffer prepared with 40% H2 (18)O allowed the assignment of an N-glycosylation site. Five main paucimannosidic N-glycans were identified, three of which were exclusively α(1-6)-fucosylated at the proximal GlcNAc. A considerable portion of these N-glycans are anionic species sulfated on either the 4- or the 6-position of the α(1-6)-mannose residue of the core. The application of chemically and enzymatically modified variants of the toxin in an animal model in guinea pigs showed that the pro-inflammatory and immunological reactions, e.g. disseminated fibrin deposition and activation of neutrophils, are due to the presence of sulfate-linked groups and not on disulfide bonds, as demonstrated by the reduction and S-alkylation of the toxin. On the other hand, the hemorrhagic vascular lesions observed are attributed to the proteolytic activity of the toxin. Thus, N-glycan sulfation may constitute a defense mechanism against predators.

Interleukin (IL)-6 has been considered as an osteolytic factor involved in periodontal disease. However, the function of IL-6 in osteoblastic differentiation of periodontal ligament cells is not clear. We examined the effects of IL-6 and its soluble receptor (sIL-6R) on osteoblastic differentiation of periodontal ligament cells. Osteoblastic differentiation was induced by ascorbic acid. Osteoblast markers, including alkaline phosphatase activity and Runx2 gene expression, were examined. The mechanism of action of IL-6 on osteoblastic differentiation was evaluated by insulin-like growth factor (IGF)-I production and specific inhibitors for the IL-6-signaling molecule. IL-6/sIL-6R enhanced alkaline phosphatase activity and Runx2. Alkaline phosphatase activity was reduced by anti-IGF-I antibody. Mitogen-activated protein kinase and Janus protein tyrosine kinase inhibitors diminished alkaline phosphatase induced by IL-6/sIL-6R. We conclude that IL-6/sIL-6R increases ascorbic-acid-induced alkaline phosphatase activity through IGF-I production, implying that IL-6 acts not only as an osteolytic factor, but also as a mediator of osteoblastic differentiation in periodontal ligament cells.

Interleukin-11/ascorbic acid induced the osteoblastic differentiation of periodontal ligament cells through type 1 collagen production and janus kinase/signal transducers and activator of transcription, and MAPK signaling pathways were involved in this process. These findings suggest that interleukin-11 may function as an osteopromotive cytokine, stimulating the osteoblastic differentiation of periodontal ligament cells mainly through the synthesis of type 1 collagen and possibly by the induction of tissue inhibitor of metalloproteinase-1.