Mistletoe extract Fraxini inhibits the proliferation of liver cancer by down-regulating c-Myc expression.

Mistletoe (Viscum album) is a type of parasitic plant reported to have anticancer activity including in hepatocellular carcinoma (HCC). However, the mechanism of mistletoe's anticancer activity, and its effectiveness in treating HCC are not fully understood. We report here that mistletoe extracts, including Fraxini (grown on ash trees) and Iscador Q and M (grown on oak and maple trees), exert strong antiproliferative activity in Hep3B cells, with median inhibitory concentrations (IC50) of 0.5 µg/mL, 7.49 µg/mL, and 7.51 µg/mL, respectively. Results of Reversed Phase Proteomic Array analysis (RPPA) suggests that Fraxini substantially down-regulates c-Myc expression in Hep3B cells. Fraxini-induced growth inhibition (at a concentration of 1.25 µg/ml) was less pronounced in c-Myc knockdown Hep3B cells than in control cells. Furthermore, in the Hep3B xenograft model, Fraxini-treated (8 mg/kg body weight) mice had significantly smaller tumors (34.6 ± 11.9 mm3) than control mice (161.6 ± 79.4 mm3, p < 0.036). Similarly, c-Myc protein expression was reduced in Fraxini treated Hep3B cell xenografts compared to that of control mice. The reduction of c-Myc protein levels in vitro Hep3B cells appears to be mediated by the ubiquitin-proteasome system. Our results suggest the importance of c-Myc in Fraxini's antiproliferative activity, which warrants further investigation.

Peptide Vaccine Formulation Controls the Duration of Antigen Presentation and Magnitude of Tumor-Specific CD8+ T Cell Response.

Despite remarkable progresses in vaccinology, therapeutic cancer vaccines have not achieved their full potential. We previously showed that an excessively long duration of Ag presentation critically reduced the quantity and quality of vaccination-induced T cell responses and subsequent antitumor efficacy. In this study, using a murine model and tumor cell lines, we studied l-tyrosine amino acid-based microparticles as a peptide vaccine adjuvant with a short-term Ag depot function for the induction of tumor-specific T cells. l-Tyrosine microparticles did not induce dendritic cell maturation, and their adjuvant activity was not mediated by inflammasome activation. Instead, prolonged Ag presentation in vivo translated into increased numbers and antitumor activity of vaccination-induced CD8+ T cells. Indeed, prolonging Ag presentation by repeated injection of peptide in saline resulted in an increase in T cell numbers similar to that observed after vaccination with peptide/l-tyrosine microparticles. Our results show that the duration of Ag presentation is critical for optimal induction of antitumor T cells, and can be manipulated through vaccine formulation.

Positional stable isotope tracer analysis reveals carbon routes during ammonia metabolism of Aedes aegypti mosquitoes.

In Aedes aegypti females, the ammonia released during blood meal digestion is partially metabolized to facilitate the disposal of excess nitrogen. In this study, we used low- and high-resolution liquid chromatography-mass spectrometry (LC/MS) techniques to investigate the role of glucose during ammonia detoxification. Mosquitoes were fed a blood meal supplemented with [1,2-13C2]glucose, and downstream metabolites were measured for 24 h. Quantification of [13C] amino acids in the entire mosquito body was conducted without sample derivatization using selected reaction monitoring of mass transitions that are indicative of the structural position of [13C] atom incorporation. Identification of unlabeled and [13C] isotopologs of 43 compounds, including amino acids, amino acid derivatives, and organic acids, was performed by high-resolution LC/MS techniques. Blood-fed mosquitoes synthesized [13C] metabolites in mainly 2 carbon positions from [1,2-13C2]glucose. [13C2]Ala and [13C2]Pro were the most abundant and rapidly labeled amino acids synthesized. Additional [13C] amino acids, [13C] amino acid derivatives, and [13C] organic acids in 1 or 2 carbon positions were also identified. Two kinetic routes were proposed based on the incorporation of a [13C] atom at position 1 in specific amino acids. Our findings provide evidence that glucose is used for ammonia detoxification and [13C] uric acid synthesis through multiple metabolic pathways, uncovering a metabolic link at the carbon atomic level in ammonia metabolism of A. aegypti-Horvath, T. D., Dagan, S., Lorenzi, P. L., Hawke, D. H., Scaraffia, P. Y. Positional stable isotope tracer analysis reveals carbon routes during ammonia metabolism of Aedes aegypti mosquitoes.