Structure and characterization of hamster IL-12 p35 and p40.

Complementary DNAs coding for two subunits of hamster interleukin-12 (IL-12), p35 and p40, were cloned from a hamster dendritic cell (DC) cDNA library. The cloning demonstrated that hamster IL-12 consisted of a p35 subunit with 216 amino acid (aa) residues and a p40 subunit with 327 aa. Structural comparison of hamster p35 and p40 at the protein level showed the highest homologies with each counterpart of sigmodon (hispid cotton rat). The gene expressions of hamster IL-12 p35 and p40 in bone marrow (BM) cells cultured in the presence of mouse granulocyte macrophage-colony-stimulating factor (mGM-CSF) and IL-4 were up-regulated during culture. Immunoblot analysis of 293 cells transfected with hamster p35 and p40 expression vectors suggested the presence of a covalently linked p35/p40 heterodimer. Furthermore, supernatant from the 293 cells transfected with both expression vectors induced the up-regulation of interferon-gamma (IFN-gamma) mRNA in hamster splenocytes, indicating that the p35/p40 heterodimer IL-12 protein present in the supernatant was functional. These results suggest that the vectors containing hamster IL-12 cDNA might be suitable tools for developing an immunotherapeutic approach against experimental cancer in a hamster model.

Hamster DEC-205, its primary structure, tissue and cellular distribution.

DEC-205, a putative antigen uptake receptor, belongs to a family of transmembrane C-type lectins. This molecule is known to be one of the most authentic markers for the lineage of dendritic cells. In the present study, we determined the primary structure, tissue distribution and cellular localization of hamster DEC-205. The multi-domain structure of mouse and human DEC-205 was completely conserved in hamster with the overall identity of approximately 80%. DEC-205 transcripts were detected in the thymus and bone marrow cells cultured in the presence of mouse granulocyte macrophage colony-stimulating factor and interleukin-4 in which the DEC-205 expression was up-regulated in the course of cultures. Hamster DEC-205 was mainly detected on cell membrane and shown to mediate the uptake of flourescein isothiocyanate-conjugated ovalbumin. DEC-205 is a highly conserved molecule across the species suggesting its fundamental role in the immune system.

Anti-cachectic effect of ghrelin in nude mice bearing human melanoma cells.

Ghrelin is a novel brain-gut peptide that stimulates food intake and body weight gain. We studied the anabolic effect of ghrelin in a cancer cachexia mouse model. SEKI, a human melanoma cell line, was inoculated into nude mice to examine the effects of ghrelin on food intake and body weight. The intraperitoneal administration of ghrelin twice a day (6 nmol/mice/day) for 6 days suppressed weight loss in SEKI-inoculated mice and increased the rate of weight gain in vehicle-treated nude mice. Ghrelin administration also increased food intake in both SEKI- and vehicle-treated mice. Both the weight of white adipose tissue and the plasma leptin concentration were reduced in tumor-inoculated mice compared with vehicle-treated mice; these factors increased following ghrelin administration. The levels of both ghrelin peptide and mRNA in the stomach were upregulated in tumor-inoculated mice. The anabolic effect of ghrelin efficiently reverses the cachexia in mice bearing SEKI human melanoma. Ghrelin therefore may have a therapeutic ability to ameliorate cancer cachexia.