T cell function in cancer patients is usually impaired due to the constitutive activation of immune checkpoint inhibitors. This state is known as 'exhaustion' and is often associated with the inefficient control of tumors or persistent infections. In this work, we investigated the role of leukemia cell-derived microvesicles (MVs) in T cell exhaustion. Following incubation with MVs from various sources, all T cell subtypes exhibited the exhaustion phonotype and impaired cytokine secretion in vitro. Mice models also showed the connection between immune checkpoint inhibitors and MV injection. Sequencing and bioinformatics analyses indicated that a number of transcription factors and microRNAs (miRNAs) were attributable to the dysregulation of pathways and exhaustion in T cells. Further work revealed that functional miR-92a-3p, miR-21-5p, miR-16-5p, miR-126 and miR-182-5p in MVs could be delivered into T cells to induce the exhaustion phenotype. SerpinB2, IL-1β and CXCL5, which are mediators of the NF-κB pathway, were identified as the targets of the miRNAs mentioned above. We demonstrated that leukemia-derived MVs could initiate T cell exhaustion via the progressive temporal delivery of multiple exogenous miRNAs into T cells and the subsequent interaction of these miRNAs with their targets. Therefore, MVs can be expected not only to become new indicators of the T cell status in patients but also to be used as novel targets for personalized patient treatment.

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, and numerous oncogenes are associated with this disease. Oxysterol-binding protein-related protein 8 (ORP8) is essential for cell growth, migration and the modulation of mitochondrial respiration and morphology. However, the underlying role of ORP8 in NSCLC remains unclear. In the present study, it was reported that the expression of ORP8 was low in NSCLC cells and tissues. The ORP8 expression levels were analyzed by immunohistochemistry (IHC), quantitative real-time PCR (qPCR) and western blot analysis. ORP8 overexpression inhibited cell growth and induced apoptosis in NSCLC cells with MTS, anchorage-independent growth and Hoechst 33342 staining assay. Further experiments demonstrated that ORP8 overexpression induced the apoptosis of NSCLC cells via the release of cytochrome c from mitochondria into the cytoplasm with western blot analysis and confocal microscopy results. In addition, qPCR analysis showed that miR-421 was upregulated in NSCLC cell lines, with the bioinformatics analysis, western blot analysis and Dual-Luciferase reporter assay, it was determined that miR-421 could target ORP8. The inhibition of cell proliferation via ORP8 overexpression was rescued by a miR-421 mimic, which aided in maintaining the proliferative potential of the cells. Overall, the present study revealed that ORP8 may be a candidate target in the prevention and treatment of NSCLC.

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