Cancers constitutively produce and secrete into the blood and other biofluids 30-150 nm-sized endosomal vehicles called exosomes. Cancer-derived exosomes exhibit powerful influence on a variety of biological mechanisms to the benefit of the tumors that produce them. We studied the immunosuppressive ability of epithelial ovarian cancer (EOC) exosomes on two cytotoxic pathways of importance for anticancer immunity-the NKG2D receptor-ligand pathway and the DNAM-1-PVR/nectin-2 pathway. Using exosomes, isolated from EOC tumor explant and EOC cell-line culture supernatants, and ascitic fluid from EOC patients, we studied the expression of NKG2D and DNAM-1 ligands on EOC exosomes and their ability to downregulate the cognate receptors. Our results show that EOC exosomes differentially and constitutively express NKG2D ligands from both MICA/B and ULBP families on their surface, while DNAM-1 ligands are more seldom expressed and not associated with the exosomal membrane surface. Consequently, the NKG2D ligand-bearing EOC exosomes significantly downregulated the NKG2D receptor expression on peripheral blood mononuclear cells (PBMC) while the DNAM-1 receptor was unaffected. The downregulation of NKG2D receptor expression was coupled to inhibition of NKG2D receptor-ligand-mediated degranulation and cytotoxicity measured in vitro with OVCAR-3 and K562 cells as targets. The EOC exosomes acted as a decoy impairing the NKG2D mediated cytotoxicity while the DNAM-1 receptor-ligand system remained unchanged. Taken together, our results support and explain the mechanism behind the recently reported finding that in EOC, NK-cell recognition and killing of tumor cells was mainly dependent on DNAM-1 signaling while the contribution of the NKG2D receptor-ligand pathway was complementary and uncertain.

Problem To get a comprehensive picture of cytokine expression in health and disease is difficult, cytokines are transiently and locally expressed, and protein analyses are burdened by biological modifications, technical issues, and sensitivity to handling of samples. Thus, alternative methods, based on molecular techniques for cytokine mRNA analyses, are often used. We compared cytokine mRNA and protein expression to evaluate whether cytokine mRNA profiles can be used instead of protein analyses. Method of study In kinetic experiments, cytokine mRNA and protein expression of IL‐1β, IL‐6, IL‐8, TNF‐α, and TNF‐β/LTA were studied using real‐time RT‐qPCR and Luminex® microarrays in the ovarian cancer cell lines OVCAR‐3, SKOV‐3 and the T‐cell line Jurkat, after activation of transcription by thermal stress. In addition, we analyzed IL‐6 and IL‐8 mRNA and protein in a small number of ovarian cancer patients. Results Ovarian cancer cells can express cytokines on both mRNA and protein level, with 1‐4 hours’ time delay between the mRNA and protein peak and a negative Spearman correlation. The mRNA and protein expression in patient samples was poorly correlated, reflecting previous studies. Conclusion Cytokine mRNA and protein expression levels show diverging results, depending on the material analyzed and the method used. Considering the high sensitivity and reproducibility of real‐time RT‐qPCR, we suggest that cytokine mRNA profiles could be used as a proxy for protein expression for some specific purposes, such as comparisons between different patient groups, and in defining mechanistic pathways involved in the pathogenesis of cancer and other pathological conditions.

Objective: Tumor establishment, metastatic spreading and poor survival in ovarian cancer is strongly associated with progressive derangement of the patient's immune system. Accumulating evidence suggests that immune impairment is influenced by the production and presence of cytokines in the tumor microenvironment.Methods: Cytokine mRNA profiles in tumor tissue and peripheral blood mononuclear cells (PBMC) were analyzed in patients with high grade serous carcinoma (HGSC) of the ovary and compared it to patients with benign ovarian conditions and controls with normal ovaries. Cytokine assessment was done by real-time quantitative RT-PCR and specific primers and probes for 12 cytokines-IFN-γ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-15, TNF-α, TNF-β/LTA, TGF-β1, and GM-CSF chosen to distinguish between cytotoxic Th1, humoral Th2, regulatory Th3/Tr1 and inflammatory responses. Results:The cytokine mRNA response in the HGSC patients was significantly up regulated compared to patients with benign ovarian conditions and normal ovary controls confirming the immunogenicity of HGSC and implying immune recognition and reaction locally in the tumor microenvironment and systemically in the peripheral blood.There was an up-regulation of inflammatory and inhibitory cytokine mRNA promoting tumor progression, T-regulatory cell priming and T-regulatory cell-mediated immune suppression. In contrast, there was an inability to mount the crucially important IFN gamma response needed for upregulation of the cytotoxic anti-tumor response in the local microenvironment. In addition, systemic IL-4-mediated Th2 response prevailed in the peripheral blood deviating the systemic defense towards humoral immunity. Conclusions:Taken together, these results suggest local and systemic cytokine cooperation promoting tumor survival, progression and immune escape. Our study confirms and extends previous investigations and contributes to the evaluation of potential cytokine candidates for diagnostic cytokine mRNA profiles and for future therapeutic interventions based on cytokine inhibition.

Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine malignancy arising from mechanoreceptors in the basal epidermis. Due to a pronounced risk of spread and a high propensity for recurrence after treatment, immediate treatment is of utmost importance. Lambert-Eaton myasthenic syndrome (LEMS) is a paraneoplastic phenomenon affecting the muscles with autoimmune pathophysiology, and >50% of known cases are associated with an underlying malignancy. In the present report, the case of a 67-year-old man presenting with progressive proximal muscle weakness, autonomic dysfunction and involuntary weight loss is described. Symptoms and detection of voltage-gated calcium channel antibodies were consistent with LEMS. Distant metastases were found in the inguinal and iliac lymph nodes, and these were immunohistochemically confirmed to be of epithelial and neuroendocrine origin, consistent with MCC. Local radiotherapy and chemotherapy improved the symptoms; however, a change of treatment was required due to the side effects of the chemotherapy. Avelumab, an immune checkpoint inhibitor, was therefore introduced, and within a year the patient did not only experience tumor remission but also exhibited marked improvements in muscle strength and mobility. At present, 2 years later, the MCC is still in remission. To the best of our knowledge, the present report is the first to describe MCC with associated LEMS, which was successfully treated with avelumab after previous radiotherapy and chemotherapy, with both improved functional motor recovery and tumor reduction. In conclusion, the present case report demonstrated that the present treatment strategy is a potential treatment option and could thus be considered in similar cases.

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