Type I and II interferons toward ideal vaccine and immunotherapy

Introduction: Innate immunity is armed with interferons (IFNs) that link innate immunity to adaptive immunity to generate long-term and protective immune responses against invading pathogens and tumors. However, regulation of IFN production is crucial because chronic IFN responses can have deleterious effects on both antitumor and antimicrobial immunity in addition to provoking autoinflammatory or autoimmune conditions.Areas covered: Here, we focus on the accumulated evidence on antimicrobial and antitumor activities of type I and II IFNs. We first summarize the intracellular and intercellular mechanisms regulating IFN production and signaling. Then, we discuss the mechanisms modulating the dual nature of IFNs for both antitumor and antimicrobial immune responses. Finally, we review the detrimental role of IFNs for induction of autoinflammation and autoimmunity.Expert opinion: The current evidence suggests that the dual role of IFNs for antimicrobial and antitumor immunity is dependent not only on the timing, administration route, and dose of IFNs but also on the type of pathogen/tumor. Therefore, we think that combinatorial therapies involving IFN-inducing adjuvants and immune-checkpoint blockers may offer therapeutic potential, especially for cancer, whereas infectious, autoinflammatory or autoimmune diseases require fine adjustment of timing, dose, and route of the administration for candidate IFN-based vaccines or immunotherapies.

IFN-γ enhances HOS and U2OS cell lines susceptibility to γδ T cell-mediated killing through the Fas/Fas ligand pathway

Osteosarcoma is the second highest cause of cancer-related death in children and adolescents, partly due to dysfunction of the Fas/FasL signaling pathway, which leads to develop fatal metastasis. Since presenting no or low levels of Fas expression, resisting Fas ligand-induced apoptosis, and lack of FasL in the host environment, osteosarcoma cells always promote metastases growth and proliferate in the lungs. Therefore, agents, which up-regulate tumor cell surface Fas expression and function, in combination with immune cells, may be effective in treating osteosarcoma, especially lung metastases. The aim of this work was to investigate the effect of γδ T cells in combination with IFN-γ in treating osteosarcoma in vitro. In the present study, we found that IFN-γ up-regulated the expression of Fas in osteosarcoma cell lines, HOS and U2OS, resulting in an enhanced susceptibility of cells to γδ T cells lyses. Moreover, this cytotoxicity was prevented by treatment with FasL-blocking antibodies. These data suggest that adoptive transfer of γδ T cells in combination with IFN-γ may substantially increase anti-osteosarcoma activities and represent a novel strategy for osteosarcoma adjunct immunotherapy.

Anti-melanoma activity of the 9.2.27PE immunotoxin in dacarbazine resistant cells

We have earlier shown that the 9.2.27 Pseudomonas Exotoxin A (PE) immunotoxin (IT) efficiently kills melanoma cells through inhibition of protein synthesis followed by some morphologic and biochemical features of apoptosis, a different cell killing mechanism than the one caused by Dacarbazine (DTIC), a chemotherapeutic drug used to treat malignant melanoma. To examine whether induced DTIC resistance also is a determining factor for the effectiveness of 9.2.27PE IT, we developed a DTIC resistant subline, FEMX-200DR, from the DTIC sensitive cell line FEMX. The cell variants were treated with 9.2.27PE, an IT binding to the high molecular weight-melanoma associated antigen (HMW-MAA) expressed on most malignant melanoma cells. The IT was equally effective in killing the FEMX-200DR and the FEMX cells, and the cell death was primarily caused by inhibition of protein synthesis. The DNA repair enzyme and apoptotic marker PARP, a substrate of caspase-3, was inactivated, although we observed only a minor activation of caspase-3 and caspase-8, intracellular proteases involved in apoptosis. In addition to being DTIC resistant, the FEMX-200DR cells were also more resistant to apoptosis than the parent cells as a 3 times higher concentration of the apoptotic inducer Staurosporine was needed to obtain IC50. Furthermore, in early passage malignant melanoma cell lines established from lymph node metastases, the 9.2.27PE caused a time-dependent and dose-dependent decrease in cell viability independent of their DTIC sensitivity. These findings show that the 9.2.27PE IT efficiently can cause cell death in malignant melanoma cells independent of their level of resistance to apoptosis and DTIC.

Signal transduction mechanisms involved in S100A4-induced activation of the transcription factor NF-kappaB

BACKGROUND

The metastasis-promoting protein S100A4 activates the transcription factor NF-kappaB through the classical NF-kappaB activation pathway. The upstream signal transduction mechanisms leading to increased NF-kappaB activity are, however, incompletely characterized.

METHODS

The human osteosarcoma cell line II-11b was stimulated with recombinant S100A4 in the presence or absence of inhibitors of common signal transduction pathways, and NF-kappaB activity was examined using a luciferase-based reporter assay and phosphorylation of IkappaBalpha. mRNA expression was analyzed by real-time RT-PCR, protein expression was examined by Western blotting and IKK activity was measured using an in vitro kinase assay. The role of upstream kinases and the cell surface receptor RAGE was investigated by overexpression of dominant negative proteins and by siRNA transfection.

RESULTS

The Ser/Thr kinase inhibitors H-7 and staurosporine inhibited S100A4-induced IkappaBalpha phosphorylation and subsequent NF-kappaB activation. The protein tyrosine kinase inhibitor genistein and the phospholipase C inhibitor compound 48/80 had a partial inhibitory effect on IkappaBalpha phosphorylation, whereas inhibitors of protein kinase C, G-protein coupled receptors and PI 3-kinases had no effect on the level of phosphorylation. Interestingly, S100A4 treatment induced activating phosphorylations of IKKalpha/beta, but neither H-7 nor staurosporine was able to significantly inhibit IKK activation. Dominant negative MEKK1 or NIK did not inhibit S100A4-induced NF-kappaB activity, and S100A4 stimulation did not influence AKT phosphorylation. Furthermore, diminished expression of the putative S100 protein receptor RAGE did not affect the observed phosphorylation of IkappaBalpha.

CONCLUSIONS

S100A4 activates NF-kappaB by inducing phosphorylation of IKKalpha/beta, leading to increased IkappaBalpha phosphorylation. The Ser/Thr kinase inhibitors H-7 and staurosporine attenuated S100A4-induced NF-kappaB activation and inhibited IKK-mediated phosphorylation of IkappaBalpha. S100A4-induced NF-kappaB activation was independent of the putative S100 protein receptor RAGE and the Ser/Thr kinases MEKK1, NIK and AKT. These findings lead to increased understanding of S100A4 signaling, which may contribute to the identification of novel targets for anti-metastatic therapy.

Activation of NF-kappaB by extracellular S100A4: analysis of signal transduction mechanisms and identification of target genes

The metastasis-promoting protein S100A4 stimulates metastatic progression through both intracellular and extracellular functions. Extracellular activities of S100A4 include stimulation of angiogenesis, regulation of cell death and increased cell motility and invasion, but the exact molecular mechanisms by which extracellular S100A4 exerts these effects are incompletely elucidated. The aim of the present study was to characterize S100A4-induced signal transduction mechanisms and to identify S100A4 target genes. We demonstrate that extracellular S100A4 activates the transcription factor NF-kappaB in a subset of human cancer cell lines through induction of phosphorylation and subsequent degradation of the NF-kappaB inhibitor IkappaBalpha. Concomitantly, S100A4 induced a sustained activation of the MAP kinase JNK, whereas no increased activity of the MAP kinases p38 or ERK was observed. Microarray analyses identified 136 genes as being significantly regulated by S100A4 treatment, and potentially interesting S100A4-induced gene products include IkappaBalpha, p53, ephrin-A1 and optineurin. Increased expression of ephrin-A1 and optineurin was validated using RT-PCR, Western blotting and functional assays. Furthermore, S100A4-stimulated transcription of these target genes was dependent on activation of the NF-kappaB pathway. In conclusion, these findings contribute to the understanding of the complex molecular mechanisms responsible for the diverse biological functions of extracellular S100A4, and provide further evidence of how S100A4 may stimulate metastatic progression.