Melanoma has a high propensity for metastasis and accounts for 80% of skin cancer-related deaths. Despite the progress in melanoma therapeutics over the last several years, melanoma remains a challenge in clinical oncology. The immune system plays an important role in controlling and eliminating cancer. However, tumors often evade/escape immune attack by modifying their phenotypes and inducing immunosuppression. Recent breakthrough in treating cancers with immune checkpoint inhibitors has fueled the intensive investigation of new therapeutic targets, including negative regulators of adaptive and innate immune systems. We have found that human metastatic melanoma cells spontaneously secrete biologically active interleukin (IL)-1? in the absence of exogenous stimuli because of constitutive activation of IL-1 receptor signaling and a multi-protein complex, ?inflammasome?, exhibiting a feature of ?autoinflammation? (IL-1?-mediated dysregulation of immune system). IL-1? is a pleiotropic pro-inflammatory cytokine and plays a critical role in tumor progression, immunosuppression and chemoresistance. Peripheral blood is an information reservoir and represents systemic processes altered by the presence of tumor cells. We conducted transcriptome profiling of whole blood cells from melanoma patients, and identified differentially expressed genes in human melanoma blood. Of these, we identified a unique cytokine, IL-37, which was highly upregulated in metastatic melanoma blood. IL-37 is a homolog of the IL-1 cytokine family. Dinarello (co-I)?s group has found that IL-37 is a novel inhibitor of innate immunity. PI?s group has found that IL-37 is a novel inhibitor of adaptive immunity. IL-37 is induced in pro-inflammatory milieu containing IL-1. We hypothesize that IL-37 is induced by autoinflammation in human melanoma, leading to tumor-induced immunoevasion. We propose to test this hypothesis using tumor and blood samples from melanoma patients (in Aim 1) and unravel the immunoevasive mechanisms of action of IL-37 in tumor cells (in Aim 2) and blood cells (in Aim 3) in melanoma.
The specific aims are:
Aim 1 : To identify cellular source of IL-37 expression in human melanoma samples and determine the link between IL-37 and autoinflammation in human melanoma.
Aim 2 : To define biological and mechanistic effects of IL-37 in melanoma cells.
Aim 3 : To define biological and mechanistic effects of IL-37 in blood cells. IL-37, an inhibitor of innate and adaptive immunity, has not been investigated in tumor immunity. Elucidating the link between autoinflammation and immune escape, and understanding the role of IL-37 in tumor immune escape is critical for clinical success in melanoma and will lead to the development of effective therapeutic agents for cancer.
The risk of developing melanoma doubles if an individual is exposed to >5 sunburns at any age. Sun exposure is part of the daily life for U.S. troops, and the exposure during US military service has been linked to increased melanoma incidence. Furthermore, melanoma is more common than other cancers in young women, an increasingly significant population in the VA and in the active-duty military. Despite the progress in breakthrough therapeutics over the last several years, melanoma remains a challenge in clinical oncology. An immune response to melanoma cells is often generated and augmented by therapeutics, however tumor cells escape from the destruction. Thus, understanding mechanisms responsible for immune escape is critical for the successful treatment of melanoma and prevention of tumor relapse for VA patients. We found that human melanoma cells exhibit a feature of IL-1-mediated autoinflammation and that an immunosuppressive cytokine, IL-37, is elevated in melanoma blood samples. We will study the role of IL-37 in human melanoma.
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