Tumor-specific CD8+T cells are exposed to persistent antigenic stimulation which induces a dysfunctional state called “exhaustion.” Though functioning to limit damage caused by immune response, T cell exhaustion leads to attenuated effector function whereby cytotoxic CD8+T cells fail to control tumor progression in the late stage. This pathway is a dynamic process from activation to “progenitor exhaustion” through to “terminally exhaustion” with distinct properties. With the rapid development of immunotherapy via enhancing T cell function, new studies are dissecting the mechanisms and identifying specific biomarkers of dynamic differentiation during the process of exhaustion. Further, although immune checkpoint inhibitors (ICIs) have achieved great success in clinical practice, most patients still show limited efficacy to ICIs. The expansion and differentiation of progenitor exhausted T cells explained the success of ICIs while the depletion of the progenitor T cell pool and the transient effector function of terminally exhausted T cells accounted for the failure of immune monotherapy in the context of exorbitant tumor burden. Thus, combination strategies are urgent to be utilized based on the reduction of tumor burden or the expansion of the progenitor T cell pool. In this review, we aim to introduce the concept of homeostasis of the activated and exhausted status of CD8+T cells in the tumor immune microenvironment, and present recent findings on dynamic differentiation process during T cell exhaustion and the implications for combination strategies in immune therapy.

Macrophages have been shown to demonstrate a high level of plasticity, with the ability to undergo dynamic transition between M1 and M2 polarized phenotypes. We investigate long non-coding RNA (lncRNA) cox-2 in macrophage polarization and the regulatory mechanism functions in hepatocellular carcinoma (HCC). Lipopolysaccharide (LPS) was used to induce RAW264.7 macrophages into M1 type, and IL-4 was to induce RAW264.7 macrophages into M2 type. We selected mouse hepatic cell line Hepal-6 and hepatoma cell line HepG2 for co-incubation with M1 or M2 macrophages. Quantitative real-time PCR was used to detect the expressions of lncRNA cox-2 and mRNAs. ELISA was conducted for testing IL-12 and IL-10 expressions; Western blotting for epithelial mesenchymal transition related factors (E-cadherin and Vimentin). An MTT, colony formation assay, flow cytometry, transwell assay, and stretch test were conducted to test cell abilities. The M1 macrophages had higher lncRNA cox-2 expression than that in the non-polarized macrophages and M2 macrophages. The lncRNA cox-2 siRNA decreased the expression levels of IL-12, iNOS, and TNF-α in M1 macrophages, increased the expression levels of IL-10, Arg-1, and Fizz-1 in M2 macrophages (all P < 0.05). The lncRNA cox-2 siRNA reduces the ability of M1 macrophages to inhibit HCC cell proliferation, invasion, migration, EMT, angiogenesis and facilitate apoptosis while strengthening the ability of M2 macrophages to promote proliferation HCC cell growth and inhibit apoptosis. These findings indicate that lncRNA cox-2 inhibits HCC immune evasion and tumor growth by inhibiting the polarization of M2 macrophages.

The recent Middle East respiratory syndrome coronavirus (MERS-CoV), Ebola and Zika virus outbreaks exemplify the continued threat of (re-)emerging viruses to human health, and our inability to rapidly develop effective therapeutic countermeasures. Many viruses, including MERS-CoV and the Crimean-Congo hemorrhagic fever virus (CCHFV) encode deubiquitinating (DUB) enzymes that are critical for viral replication and pathogenicity. They bind and remove ubiquitin (Ub) and interferon stimulated gene 15 (ISG15) from cellular proteins to suppress host antiviral innate immune responses. A variety of viral DUBs (vDUBs), including the MERS-CoV papain-like protease, are responsible for cleaving the viral replicase polyproteins during replication, and are thereby critical components of the viral replication cycle. Together, this makes vDUBs highly attractive antiviral drug targets. However, structural similarity between the catalytic cores of vDUBs and human DUBs complicates the development of selective small molecule vDUB inhibitors. We have thus developed an alternative strategy to target the vDUB activity through a rational protein design approach. Here, we report the use of phage-displayed ubiquitin variant (UbV) libraries to rapidly identify potent and highly selective protein-based inhibitors targeting the DUB domains of MERS-CoV and CCHFV. UbVs bound the vDUBs with high affinity and specificity to inhibit deubiquitination, deISGylation and in the case of MERS-CoV also viral replicative polyprotein processing. Co-crystallization studies further revealed critical molecular interactions between UbVs and MERS-CoV or CCHFV vDUBs, accounting for the observed binding specificity and high affinity. Finally, expression of UbVs during MERS-CoV infection reduced infectious progeny titers by more than four orders of magnitude, demonstrating the remarkable potency of UbVs as antiviral agents. Our results thereby establish a strategy to produce protein-based inhibitors that could protect against a diverse range of viruses by providing UbVs via mRNA or protein delivery technologies or through transgenic techniques.

Hepatocellular carcinoma (HCC) is one of the most common human malignancies and the third leading cause of cancer mortality worldwide. The development and progression of HCC is a complicated process, involving the deregulation of multiple genes that are essential to cell biological processes. Recently, microRNAs (miRNAs) have been suggested to be closely associated with tumorigenesis. Our study showed that miR-184 is upregulated in HCC cell lines and tissues. Overexpression of miR-184 in HCC cells increased cell proliferation, tumorigenicity, and cell cycle progression, whereas inhibition of miR-184 reduced cell proliferation, tumorigenicity, and cell cycle progression. Additionally, we identified SOX7 as a direct target of miR-184. Ectopic expression of miR-184 led to downregulation of the SOX7 protein, resulting in upregulation of c-Myc, Cyclin D1, and phosphorylation of Rb. Our findings suggested that miR-184 represents a potential onco-miR and plays an important role in HCC progression by suppressing SOX7 expression.

Neuroblastoma (NB), ganglioneuroblastoma intermixed (GNBi) and ganglioneuroblastoma nodular (GNBn) are neuroblastic tumors that present with a wide range of symptoms and variable prognoses. We retrospectively reviewed the pretreatment clinical (age, sex and tumor stage) and biological (MYCN amplification; and levels of lactate dehydrogenase, ferritin and neuron-specific enolase) characteristics of 279 patients who were diagnosed with pathologically confirmed NB and GNB from January 2005 to December 2015. The median age at diagnosis increased with grade of differentiation (NB: 28.9 months; GNBn: 38.4 months; GNBi: 47.5 months; p < 0.01). NB patients were more frequently diagnosed with adrenal tumors and had a higher prevalence of abnormal serum ferritin at the time of diagnosis (60.0% vs. 40.0% vs. 12.0%, P<0.001), NSE (96.0% vs. 93.0% vs. 81.0%, P=0.013) when compared with GNBn and GNBi patients. The prevalence rates of disseminated tumors and MYCN amplified tumors were lower in the GNBi group than in the GNBn and NB groups (13.0% vs. 25.0% vs. 44.0%, P=0.002; 0 vs. 14.0% vs. 26.0%, P=0.032, respectively). The overall survival (OS) of patients with GNB was significantly better than that of patients with NB (GNBi: 100%, GNBn: 74.5±11.4%, NB: 50.8±4.5%, respectively; P<0.01). Our study revealed that both NB and GNB have a wide range of presentations, and clinicians should be aware of both typical and atypical symptoms and signs. Children with GNB (especially GNBi) were more likely to present favorable prognostic factors than their NB counterparts, which consequently lead to better outcomes and longer survival for these patients.