Head and neck squamous cell carcinoma (HNSCC) is the sixth most frequent cancer worldwide. The pregnane X receptor (PXR) is a nuclear receptor regulating several target genes associated with cancer malignancy. We here demonstrated a significant effect of PXR on HNSCC cell growth, as evidenced in PXR knock-down experiments. PXR transcriptional activity is more importantly regulated by the presence of coactivators and corepressors than by PXR protein expression. To date, there is scarce information on the regulation of PXR in HNSCC and on its role in the pathogenesis of this disease. Coactivator and corepressor expression was screened through qRT-PCR in 8 HNSCC cell lines and correlated to PXR activity, determined by using a reporter gene assay. All cell lines considerably expressed all the cofactors assessed. PXR activity negatively correlated with nuclear receptor corepressor 2 (NCoR2) expression, indicating a major role of this corepressor in PXR modulation and suggesting its potential as a surrogate for PXR activity in HNSCC. To test the association of NCoR2 with the malignant phenotype, a subset of three cell lines was transfected with an over-expression plasmid for this corepressor. Subsequently, cell growth and chemoresistance assays were performed. To elucidate the mechanisms underlying NCoR2 effects on cell growth, caspase 3/7 activity and protein levels of cleaved caspase 3 and PARP were evaluated. In HNO97 cells, NCoR2 over-expression decreased cell growth, chemoresistance and increased cleaved caspase 3 levels, caspase activity and cleaved PARP levels. On the contrary, in HNO124 and HNO210 cells, NCoR2 over-expression increased cell growth, drug resistance and decreased cleaved caspase 3 levels, caspase activity and cleaved PARP levels. In conclusion, we demonstrated a role of PXR and NCoR2 in the modulation of cell growth in HNSCC. This may contribute to a better understanding of the highly variable HNSCC therapeutic response.

With the aim to improve the efficacy of therapeutic vaccines that target self-antigens, we have developed a novel fusion protein vaccine on the basis of the C-terminal multimerizing end of the variable lymphocyte receptor B (VLRB), the Ig equivalent in jawless fishes. Recombinant vaccines were produced in by fusing the VLRB sequence to 4 different cancer-associated target molecules. The anti-self-immune response generated in mice that were vaccinated with VLRB vaccines was compared with the response in mice that received vaccines that contained bacterial thioredoxin (TRX), previously identified as an efficient carrier. The anti-self-Abs were analyzed with respect to titers, binding properties, and duration of response. VLRB-vaccinated mice displayed a 2- to 10-fold increase in anti-self-Ab titers and a substantial decrease in Abs against the foreign part of the fusion protein compared with the response in TRX-vaccinated mice ( < 0.01). VLRB-generated Ab response had duration similar to the corresponding TRX-generated Abs, but displayed a higher diversity in binding characteristics. Of importance, VLRB vaccines could sustain an immune response against several targets simultaneously. VLRB vaccines fulfill several key criteria for an efficient therapeutic vaccine that targets self-antigens as a result of its small size, its multimerizing capacity, and nonexposed foreign sequences in the fusion protein.-Saupe, F., Reichel, M., Huijbers, E. J. M., Femel, J., Markgren, P.-O., Andersson, C. E., Deindl, S., Danielson, U. H., Hellman, L. T., Olsson, A.-K. Development of a novel therapeutic vaccine carrier that sustains high antibody titers against several targets simultaneously.

Galectin-1 (Gal1) is a glycan-binding protein that promotes tumor progression by several distinct mechanisms. Through direct binding to vascular endothelial growth factor (VEGF)-receptor 2, Gal1 is able to induce VEGF-like signaling, which contributes to tumor angiogenesis. Furthermore, several studies have demonstrated an immunosuppressive function of Gal1 through effects on both effector and regulatory T cells. Elevated Gal1 expression and secretion have been shown in many tumor types, and high Gal1 serum levels have been connected to poor prognosis in cancer patients. These findings suggest that therapeutic strategies directed against Gal1 would enable simultaneous targeting of angiogenesis, immune evasion and metastasis. In the current study, we have analyzed the potential of Gal1 as a cancer vaccine target. We show that it is possible to generate high anti-Gal1 antibody levels in mice immunized with a recombinant vaccine protein consisting of bacterial sequences fused to Gal1. Growth of Gal1 expressing melanomas was significantly impaired in the immunized mice compared to the control group. This was associated with improved perfusion of the tumor vasculature, as well as increased infiltration of macrophages and cytotoxic T cells (CTLs). The level of granzyme B, mainly originating from CTLs in our model, was significantly elevated in Gal1 vaccinated mice and correlated with a decrease in tumor burden. We conclude that vaccination against Gal1 is a promising pro-immunogenic approach for cancer therapy that could potentially enhance the effect of other immunotherapeutic strategies due to its ability to promote CTL influx in tumors.

IFN-gamma receptor deficient (IFN-gamma R-/-) mice, immunized with different developmental stages of malaria parasites, were used to define the mechanisms of protection against the various stages of this infection. IFN-gamma R-/- mice failed to develop protective immunity against Plasmodium yoelii sporozoites or liver stages, upon immunization with a single dose of irradiated sporozoites, whereas in immunized wild-type mice, parasite development was strongly inhibited. Immunized wild-type mice expressed high levels of inducible nitric oxide synthase (iNOS) mRNA in their liver, upon challenge with viable sporozoites, whereas only background levels of iNOS were detected in immunized IFN-gamma R-/- mice. In contrast, after immunization with multiple doses of irradiated sporozoites, both IFN-gamma R-/- and wild-type mice mounted an immune response, which strongly inhibited the development of liver stage parasites. In both types of mice, protection occurred in the absence of appreciable expression of liver iNOS mRNA. As for the course of the erythrocytic phase of infection by nonlethal malaria species, P. yoelii yoelii and P. chabaudi adami, we observed only a moderately prolonged parasitemia in IFN-gamma R-/- mice compared with wild-type mice, indicating that IFN-gamma may only play a modest role in immunity against erythrocytic stages. These results indicate that IFN-gamma is the main mediator of the protective mechanism that develops first upon immunization with sporozoites. However, the nature of the anti-parasite mechanism(s) changes in the course of immunization, so that multiple immunizing doses elicit additional protective mechanisms, which are independent of IFN-gamma and its receptor.