Expression of a metastatic phenotype in IFNs-primed/TNFalpha-activated B16 murine melanoma cells: role of JAK1/PKCdelta signal transduction factors

Interferons and Resistance Mechanisms in Tumors and Pathogen-Driven Diseases—Focus on the Major Histocompatibility Complex (MHC) Antigen Processing Pathway

Interferons (IFNs), divided into type I, type II, and type III IFNs represent proteins that are secreted from cells in response to various stimuli and provide important information for understanding the evolution, structure, and function of the immune system, as well as the signaling pathways of other cytokines and their receptors. They exert comparable, but also distinct physiologic and pathophysiologic activities accompanied by pleiotropic effects, such as the modulation of host responses against bacterial and viral infections, tumor surveillance, innate and adaptive immune responses. IFNs were the first cytokines used for the treatment of tumor patients including hairy leukemia, renal cell carcinoma, and melanoma. However, tumor cells often develop a transient or permanent resistance to IFNs, which has been linked to the escape of tumor cells and unresponsiveness to immunotherapies. In addition, loss-of-function mutations in IFN signaling components have been associated with susceptibility to infectious diseases, such as COVID-19 and mycobacterial infections. In this review, we summarize general features of the three IFN families and their function, the expression and activity of the different IFN signal transduction pathways, and their role in tumor immune evasion and pathogen clearance, with links to alterations in the major histocompatibility complex (MHC) class I and II antigen processing machinery (APM). In addition, we discuss insights regarding the clinical applications of IFNs alone or in combination with other therapeutic options including immunotherapies as well as strategies reversing the deficient IFN signaling. Therefore, this review provides an overview on the function and clinical relevance of the different IFN family members, with a specific focus on the MHC pathways in cancers and infections and their contribution to immune escape of tumors.

Mesenchymal Stem Cells Overexpressing IFN-β Inhibit Breast Cancer Growth and Metastases through Stat3 Signaling in a Syngeneic Tumor Model

We previously demonstrated that mesenchymal stem/stromal cells (MSC) are recruited to tumors and that IFN-β produced by MSC inhibited tumor growth in xenograft models. Because of a deficient immune system, murine xenograft models cannot fully recapitulate tumor and immune cell interactions during progression. Therefore we investigated the capacity of MSC to migrate to and engraft into primary breast tumor sites and subsequently explore mechanisms of tumor inhibition by MSC-delivered IFN-β in a syngeneic, immunocompetent murine model. Herein we report that 1) systemically administrated MSC migrate to established 4 T1 breast cancer sites and localize among the tumor-stroma border and throughout the tumor mass; 2) high levels of IFN-β secreted by MSC are detectable in the tumor microenvironment but not in circulation; 3) intratumorally produced IFN-β inactivates constitutive phosphorylation of signal transducer activator transcription factor 3 (Stat3), Src, and Akt and down-regulates cMyc and MMP2 expression in 4 T1 cells, and 4) in mice with established breast cancer IFN-β expressing MSC administered systemically resulted in inhibition of primary cancer growth and in dramatic reduction of pulmonary and hepatic metastases. 5) MSC-IFN-β treated, but not control mice, maintained normal levels of splenic mature dendritic (DC), CD8+ T cells and CD4+/Foxp3+ regulatory T-cells (Treg). Our findings suggest that MSC are capable of migrating to tumor sites in an immunocompetent environment, that IFN-β produced by MSC suppresses breast cancer growth through inhibition of Stat3 signaling, and dramatically reduces pulmonary and hepatic metastases.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s12307-010-0041-8) contains supplementary material, which is available to authorized users.

IFN inducibility of major histocompatibility antigens in tumors

Interferons represent a protein family with pleiotropic functions including immunomodulatory, cytostatic, and cytotoxic activities. Based on these effects, interferons are involved in innate as well as adaptive immunity, thereby shaping the tumor host immune responses. These cytokines, alone or in combination, have been successfully implemented for the treatment of some malignancies. However, it has been recently demonstrated that tumor cells could be resistant to interferon treatment, which may be associated with an escape of tumor cells from immune surveillance. Therefore, the aim of this chapter is to summarize the frequency of impaired interferon signal transduction, their underlying molecular mechanisms, and their clinical relevance.