Interferon- Activates Multiple STAT Proteins and Upregulates Proliferation-Associated IL-2R, c-myc, and pim-1 Genes in Human T Cells

IL-1 receptor antagonism reveals a yin-yang relationship between NFκB and interferon signaling in chronic lymphocytic leukemia

Nuclear factor kappa B (NFκB) is a pathogenic factor in chronic lymphocytic leukemia (CLL) that is not addressed specifically by current therapies. NFκB is activated by inflammatory factors that stimulate toll-like receptors (TLRs) and receptors for interleukin-1 (IL-1) family members. IL-1 is considered a master regulator of inflammation, and IL-1 receptor signaling is inhibited by the IL-1 receptor antagonist anakinra. These considerations suggested that anakinra might have a role in the treatment of CLL. Consistent with this idea, anakinra inhibited spontaneous and TLR7-mediated activation of the canonical NFκB pathway in CLL cells in vitro. However, CLL cells exhibited only weak signaling responses to IL-1 itself, and anakinra was found to inhibit NFκB along with oxidative stress in an IL-1 receptor-independent manner. Anakinra was then administered with minimal toxicity to 11 previously untreated CLL patients in a phase I dose-escalation trial (NCT04691765). A stereotyped clinical response was observed in all patients. Anakinra lowered blood lymphocytes and lymph node sizes within the first month that were associated with downregulation of NFκB and oxidative stress in the leukemia cells. However, inhibition of NFκB was accompanied by upregulation of type 1 interferon (IFN) signaling, c-MYC-regulated genes and proteins, and loss of the initial clinical response. Anakinra increased IFN signaling and survival of CLL cells in vitro that were, respectively, phenocopied by mitochondrial antioxidants and reversed by IFN receptor blocking antibodies. These observations suggest that anakinra has activity in CLL and may be a useful adjunct for conventional therapies as long as compensatory IFN signaling is blocked at the same time.

The PTPRZ1-MET/STAT3/ISG20 axis in glioma stem-like cells modulates tumor-associated macrophage polarization

Recent studies have revealed that PTPRZ1-MET (ZM) fusion plays a pivotal role in the progression of glioma to glioblastoma multiforme (GBM), thus serving as a biomarker to distinguish between primary GBM and secondary GBM (sGBM). However, the mechanisms through which ZM fusion influences this progression remain to be elucidated. GBMs with ZM showed poorer prognoses and greater infiltration of tumor-associated macrophages (TAMs) than those without ZM. Glioma stem-like cells (GSCs) and TAMs play complex roles in glioma recurrence, glioma progression and therapy resistance. In this study, we analyzed RNA-seq data from sGBM patients' glioma tissues with or without ZM fusion, and found that stemness and macrophage markers were more highly expressed in sGBM patients harboring ZM than in those without ZM fusion. ZM enhanced the self-renewal and proliferation of GSCs, thereby accelerating glioma progression. In addition, ZM-positive GSCs facilitated the infiltration of TAMs and drove their polarization toward an immunosuppressive phenotype, which was primarily accomplished through the extracellular secretion of ISG20. Our research identified the MET-STAT3-ISG20 axis within GSCs, thus demonstrating the critical role of ZM in GBM initiation and progression. Our study demonstrated that, in contrast to ZM-positive differentiated glioma cells, ZM-positive GSCs upregulated ISG20 expression through the MET-STAT3-ISG20 axis. The extracellular secretion of ISG20 recruited and induced M2-like polarization in macrophages, thereby promoting tumor progression. Our results reveal a novel mechanism involved in ZM-positive GBM pathogenesis and identify potential therapeutic targets.

Activation of the cGAS-STING-IRF3 Axis by Type I and II Interferons Contributes to Host Defense

Interferons (IFNs) activate JAK-STAT pathways to induce downstream effector genes for host defense against invaded pathogens and tumors. Here both type I (β) and II (γ) IFNs are shown that can activate the transcription factor IRF3 in parallel with STAT1. IRF3-deficiency impairs transcription of a subset of downstream effector genes induced by IFN-β and IFN-γ. Mechanistically, IFN-induced activation of IRF3 is dependent on the cGAS-STING-TBK1 axis. Both IFN-β and IFN-γ cause mitochondrial DNA release into the cytosol. In addition, IFNs induce JAK1-mediated tyrosine phosphorylation of cGAS at Y214/Y215, which is essential for its DNA binding activity and signaling. Furthermore, deficiency of cGAS, STING, or IRF3 impairs IFN-β- or IFN-γ-mediated antiviral and antitumor activities. The findings reveal a novel IRF3 activation pathway parallel with the canonical STAT1/2 activation pathways triggered by IFNs and provide an explanation for the pleiotropic roles of the cGAS-STING-IRF3 axis in host defense.

PIM kinases regulate early human Th17 cell differentiation

The serine/threonine-specific Moloney murine leukemia virus (PIM) kinase family (i.e., PIM1, PIM2, and PIM3) has been extensively studied in tumorigenesis. PIM kinases are downstream of several cytokine signaling pathways that drive immune-mediated diseases. Uncontrolled T helper 17 (Th17) cell activation has been associated with the pathogenesis of autoimmunity. However, the detailed molecular function of PIMs in human Th17 cell regulation has yet to be studied. In the present study, we comprehensively investigated how the three PIMs simultaneously alter transcriptional gene regulation during early human Th17 cell differentiation. By combining PIM triple knockdown with bulk and scRNA-seq approaches, we found that PIM deficiency promotes the early expression of key Th17-related genes while suppressing Th1-lineage genes. Further, PIMs modulate Th cell signaling, potentially via STAT1 and STAT3. Overall, our study highlights the inhibitory role of PIMs in human Th17 cell differentiation, thereby suggesting their association with autoimmune phenotypes.

TRAF3 enhances type I interferon receptor signaling in T cells by modulating the phosphatase PTPN22

Type I interferons (IFNs) are among the most powerful tools that host cells deploy against intracellular pathogens. Their effectiveness is due both to the rapid, directly antiviral effects of IFN-stimulated gene products and to the effects of type I IFN on responding immune cells. Type I IFN signaling through its receptor, IFNAR, is tightly regulated at multiple steps in the signaling cascade, including at the level of IFNAR downstream effectors, which include the kinase JAK1 and the transcriptional regulator STAT1. Here, we found that tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) enhanced the activation of JAK1 and STAT1 specifically in CD4+ T cells by preventing recruitment of the negative regulatory phosphatase PTPN22 to the IFNAR complex. The balance between signals through IFNAR and other cytokine receptors influences CD4+ T cell differentiation and function during infections. Our work reveals TRAF3 and PTPN22 as key regulators of CD4+ T cell activation by type I IFNs.

Transcriptomic analysis shows that surgical treatment is likely to influence the endometrial receptivity of patients with stage III/IV endometriosis

BACKGROUND

Endometriosis negatively affects fertility, and it is a common disease in assisted reproductive practice. Surgical removal of endometriotic lesions is widely carried out to relieve symptoms and promote fertility. But it is not intensively investigated what changes in the secretory eutopic endometrium of patients with endometriosis after surgery.

METHODS

Eighteen patients with stage III/IV endometriosis were included in the study, and they were divided into the untreated group and the treated group (6 vs. 12). Basic clinical data were compared, and transcriptomic data of the secretory eutopic endometrium were analyzed with DESeq2, Cytoscape, ClueGO, CluePedia, and Gene Set Enrichment Analysis (GSEA). CIBERSORT was used to calculate the relative abundance of 22 immune cells in the samples.

RESULTS

We determined 346 differentially expressed genes (DEGs) using DESeq2. These DEGs were used to enrich seven Gene Ontology terms including three associated with immune processes and one correlated to prostaglandin using ClueGO and CluePedia. GSEA enriched 28 Gene Ontology terms in the treated group mainly associated with immune and blood pressure regulation process. Compared to the untreated group, the relative abundance of resting CD4+ memory T cells [0.218 (0.069, 0.334) vs. 0.332 (0.181, 0.429), P = 0.022] and the even less abundant memory B cells [0.001 (0.000, 0.083) vs. 0.033 (0.007, 0.057), P = 0.049] are significantly decreased in the treated group.

CONCLUSION

Surgical treatment of stage III/IV endometriosis influences some genes and biological processes related to endometrial receptivity, but more evidence is needed.

Profiling transcription factor sub-networks in type I interferon signaling and in response to SARS-CoV-2 infection

Type I interferons (IFN α/β) play a central role in innate immunity to respiratory viruses, including coronaviruses. In this study, transcription factor profiling in the transcriptome was used to gain novel insights into the role of inducible transcription factors in response to type I interferon signaling in immune cells and in lung epithelial cells after SARS-CoV-2 infection. Modeling the interferon-inducible transcription factor mRNA data in terms of distinct sub-networks based on biological functions such as antiviral response, immune modulation, and cell growth revealed enrichment of specific transcription factors in mouse and human immune cells. Interrogation of multiple microarray datasets revealed that SARS-CoV-2 induced high levels of IFN-beta and interferon-inducible transcription factor mRNA in human lung epithelial cells. Transcription factor mRNA of the three sub-networks were differentially regulated in human lung epithelial cell lines after SARS-CoV-2 infection and in COVID-19 patients. A subset of type I interferon-inducible transcription factors and inflammatory mediators were specifically enriched in the lungs and neutrophils of Covid-19 patients. The emerging complex picture of type I IFN transcriptional regulation consists of a rapid transcriptional switch mediated by the Jak-Stat cascade and a graded output of the inducible transcription factor activation that enables temporal regulation of gene expression.

Therapeutic targeting of PIM KINASE signaling in cancer therapy: Structural and clinical prospects

BACKGROUND

PIM kinases are well-studied drug targets for cancer, belonging to Serine/Threonine kinases family. They are the downstream target of various signaling pathways, and their up/down-regulation affects various physiological processes. PIM family comprises three isoforms, namely, PIM-1, PIM-2, and PIM-3, on alternative initiation of translation and they have different levels of expression in different types of cancers. Its structure shows a unique ATP-binding site in the hinge region which makes it unique among other kinases.

SCOPE OF REVIEW

PIM kinases are widely reported in hematological malignancies along with prostate and breast cancers. Currently, many drugs are used as inhibitors of PIM kinases. In this review, we highlighted the physiological significance of PIM kinases in the context of disease progression and therapeutic targeting. We comprehensively reviewed the PIM kinases in terms of their expression and regulation of different physiological roles. We further predicted functional partners of PIM kinases to elucidate their role in the cellular physiology of different cancer and mapped their interaction network.

MAJOR CONCLUSIONS

A deeper mechanistic insight into the PIM signaling involved in regulating different cellular processes, including transcription, apoptosis, cell cycle regulation, cell proliferation, cell migration and senescence, is provided. Furthermore, structural features of PIM have been dissected to understand the mechanism of inhibition and subsequent implication of designed inhibitors towards therapeutic management of prostate, breast and other cancers.

GENERAL SIGNIFICANCE

Being a potential drug target for cancer therapy, available drugs and PIM inhibitors at different stages of clinical trials are discussed in detail.

Robust innate immune responses at the placenta during early gestation may limit in utero HIV transmission

In 2019, >90% of new HIV infections in infants globally occurred vertically. Studies suggest intrauterine transmission most often occurs in the third trimester; however, there are no mechanistic studies to support these observations. We therefore obtained early/mid-gestation and term placentae from 20 HIV/Hepatitis B/CMV negative women. Isolated primary placental macrophages (Hofbauer cells [HCs]) were exposed to HIV-1_BaL and/or interferon (IFN)-α, IFN-β, IFN-λ1, and RIG-I-like receptor (RLR) agonists. qRT-PCR, FACS, ELISA, Luminex, and Western blot analyses determined expression of activation markers, co-receptors, viral antigen, cytokines, antiviral genes, and host proteins. Early gestation HCs express higher levels of CCR5 and exhibit a more activated phenotype. Despite downregulation of CCR5, term HCs were more susceptible to HIV replication. Early gestation HCs displayed a more activated phenotype than term HCs and HIV exposure lead to the further up-regulation of T-cell co-stimulatory and MHC molecules. Limited HIV replication in early/mid gestation HCs was associated with increased secretion of anti-inflammatory cytokines, chemokines, and a more robust antiviral immune response. In contrast, term HCs were more susceptible to HIV replication, associated with dampening of IFN-induced STAT1 and STAT2 protein activation. Treatment of early/mid gestation and term HCs, with type I IFNs or RLR agonists reduced HIV replication, underscoring the importance of IFN and RLR signaling in inducing an antiviral state. Viral recognition and antiviral immunity in early gestation HCs may prevent in utero HIV infection, whereas diminished antiviral responses at term can facilitate transmission. Defining mechanisms and specific timing of vertical transmission are critical for the development of specific vaccines and antiviral therapeutics to prevent new HIV infections in children globally.

Mother-to-child transmission is the main source of HIV infection in children globally. Studies suggest vertical transmission most often occurs late in the third trimester; however, there are no studies to support these observations. Our study shows that gestational age plays a significant role in the ability of placental macrophages to generate robust antiviral responses, which are necessary to prevent or reduce viral burden. Specifically, we show that viral recognition by RIG-I-like receptors and robust antiviral immune responses in placental cells during early gestation may prevent in utero HIV infection. We also demonstrate that term placental macrophages are limited in their antiviral capacity due to restricted type I IFN signaling. Understanding the mechanisms and timing of vertical transmission are important to understand for the development of specific vaccines and antiviral therapeutics to prevent new HIV infections in children globally.

Secretome screening reveals immunomodulating functions of IFNα-7, PAP and GDF-7 on regulatory T-cells

Regulatory T cells (Tregs) are the key cells regulating peripheral autoreactive T lymphocytes. Tregs exert their function by suppressing effector T cells. Tregs have been shown to play essential roles in the control of a variety of physiological and pathological immune responses. However, Tregs are unstable and can lose the expression of FOXP3 and suppressive functions as a consequence of outer stimuli. Available literature suggests that secreted proteins regulate Treg functional states, such as differentiation, proliferation and suppressive function. Identification of secreted proteins that affect Treg cell function are highly interesting for both therapeutic and diagnostic purposes in either hyperactive or immunosuppressed populations. Here, we report a phenotypic screening of a human secretome library in human Treg cells utilising a high throughput flow cytometry technology. Screening a library of 575 secreted proteins allowed us to identify proteins stabilising or destabilising the Treg phenotype as suggested by changes in expression of Treg marker proteins FOXP3 and/or CTLA4. Four proteins including GDF-7, IL-10, PAP and IFNα-7 were identified as positive regulators that increased FOXP3 and/or CTLA4 expression. PAP is a phosphatase. A catalytic-dead version of the protein did not induce an increase in FOXP3 expression. Ten interferon proteins were identified as negative regulators that reduced the expression of both CTLA4 and FOXP3, without affecting cell viability. A transcriptomics analysis supported the differential effect on Tregs of IFNα-7 versus other IFNα proteins, indicating differences in JAK/STAT signaling. A conformational model experiment confirmed a tenfold reduction in IFNAR-mediated ISG transcription for IFNα-7 compared to IFNα-10. This further strengthened the theory of a shift in downstream messaging upon external stimulation. As a summary, we have identified four positive regulators of FOXP3 and/or CTLA4 expression. Further exploration of these Treg modulators and their method of action has the potential to aid the discovery of novel therapies for both autoimmune and infectious diseases as well as for cancer.

Analysis of lncRNA, miRNA, and mRNA Expression Profiling in Type I IFN and Type II IFN Overexpressed in Porcine Alveolar Macrophages

Current data is scarce regarding the function of noncoding RNAs (ncRNAs) such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) in the interferon- (IFN-) mediated immune response. This is a comprehensive study that analyzes the lncRNA and miRNA expression profiles of the type I IFN and type II IFN in porcine alveolar macrophages using RNA sequencing. There was a total of 152 overexpressed differentially expressed (DE) lncRNAs and 21 DE miRNAs across type I IFN and type II IFN in porcine alveolar macrophages. Subsequent lncRNA-miRNA-mRNA network construction revealed the involvement of 36 DE lncRNAs and 12 DE miRNAs. LncRNAs such as the XLOC_211306, XLOC_100516, XLOC_00695, XLOC_149196, and XLOC_014459 were expressed at a higher degree in the type I IFN group, while XLOC_222640, XLOC_047290, XLOC_147777, XLOC_162298, XLOC_220210, and XLOC_165237 were expressed at a higher degree in the type II IFN group. These lncRNAs were found to act as "sponges" for miRNAs such as miR-34a, miR-328, miR-885-3p, miR-149, miR-30c-3p, miR-30b-5p, miR-708-5p, miR-193a-5p, miR-365-5p, and miR-7. Their target genes FADS2, RPS6KA1, PIM1, and NOD1 were found to be associated with several immune-related signaling pathways including the NOD-like receptor, Jak-STAT, mTOR, and PPAR signaling pathways. These experiments provide a comprehensive profile of overexpressed noncoding RNAs in porcine alveolar macrophages, providing new insights regarding the IFN-mediated immune response.

Inhibition of Pim-2 kinase by LT-171-861 promotes DNA damage and exhibits enhanced lethal effects with PARP inhibitor in multiple myeloma

Multiple myeloma (MM) is a malignancy of antibody-producing plasma cells with genomic instability and genetic abnormality as its two hallmarks. Therefore, DNA damage is pervasive in MM cells, which indicates irregular DNA damage response (DDR) pathway. In this study, we demonstrated that LT-171-861, a multiple kinase inhibitor, could inhibit proliferation and induce apoptosis in MM cells. LT-171-861 promoted DDR pathway and triggered DNA damage through impeding the process of homologous recombination in double strand breaks, rather than directly elevating ROS level in MM cells. Mechanism research revealed that Pim2 inhibition was responsible for LT-171-861-indcued DNA damage and cell apoptosis. LT-171-861 mainly suppressed Pim2 kinase activity and reduced the expression of its phosphorylated substrates, such as 4EBP1 and BAD. Moreover, Olaparib, a PARP inhibitor, could enhance the antitumor effect of LT-171-861 in suppressing tumor growth in MM xenografted nude mice. Taken together, our results demonstrated that LT-171-861 showed a promising therapeutic potential for MM and had an additional lethal effect with PARP inhibitors.

Chlamydia pneumoniae-Induced IFN-Gamma Responses in Peripheral Blood Mononuclear Cells Increase Numbers of CD4+ but Not CD8+ T Effector Memory Cells

Background

Chlamydia pneumoniae causes respiratory infection in adults and children. Previous studies in our laboratory identified significantly higher in vitro T lymphocyte responses to C. pneumoniae in children with asthma compared to healthy controls which may indicate the presence of T effector memory (TEM) lymphocytes.

Aim

In the present study, healthy subjects were screened for the presence of TEM cells and their cytokines. CCR7 negative effector TEMs may indicate persistent infection with C. pneumoniae.

Methods

Peripheral blood mononuclear cells (PBMC) (1×10⁶/mL) from adult non-asthmatic subjects were infected for 1h ± C. pneumoniae TW-183 at a multiplicity of infection (MOI) = 0.1 and cultured (48 hrs). Distributions of lymphocytes (CD4+, CD8+) and TEM cells (CD4+CCR7+CD45RA+CD154+, CD8+CCR7+CD45RA+CD154+) were determined. Levels of intracellular interleukin (IL)-2, IL-4, and interferon (IFN)-gamma were measured (flow microfluorimetry); IFN-gamma was measured in supernatants (ELISA).

Results

C. pneumoniae infection led to a decrease in numbers of CD8+ TEM and CD8+CD154+ cells; CD4+TEM and CD4+CD154+ cells did not change. Numbers of TEM cells (CD4+IL-2+, CD8+ IL-2+) also decreased. However, number of TEM cells (CD4+IL4-+, CD8+ IL-4+) and (CD4+ IFN-gamma+, CD8+IFN-gamma+) did not change. When stratified according to IFN-gamma+ status, numbers of CD4+ IL-2+ and CD4+IL-4+ TEMs increased; CD8+IL-2+ and CD8+ IL-4+ TEMs decreased.

Conclusion

C. pneumoniae-induced PBMC IFN-gamma+ responses increased numbers of CD4+ IL-2+ and CD4+IL-4+ TEM cells, while CD8+IL-2+ and CD8+IL-4+ TEMs decreased. Production of IFN-gamma by C. pneumoniae infected PBMC should be further studied as a biomarker of persistent infection in humans.

STAT3 plays an important role in DNA replication by turning on WDHD1

BACKGROUND

Signal transducers and activators of transcription 3 (STAT3) is a transcription factor that plays a key role in many cellular processes such as cell growth and cancer. However, the functions and mechanisms by which STAT3 regulates cellular processes are not fully understood.

RESULTS

Here we describe a novel function of STAT3. We demonstrated that STAT3 plays an important role in DNA replication. Specifically, knockdown of STAT3 reduced DNA replication while activation and ectopic expression of STAT3 promoted DNA replication. We further identified the WD repeat and HMG-box DNA-binding protein 1 (WDHD1), which plays an important role in DNA replication initiation, as a novel STAT3 target gene that mediated the DNA replication function of STAT3. We showed that STAT3 bind the promoter/up regulatory region of WDHD1 gene.

CONCLUSIONS

These studies identified a novel function of STAT3 that is mediated by its newly identified target gene WDHD1 and have important implications.

Identification of PIM1 substrates reveals a role for NDRG1 phosphorylation in prostate cancer cellular migration and invasion

PIM1 is a serine/threonine kinase that promotes and maintains prostate tumorigenesis. While PIM1 protein levels are elevated in prostate cancer relative to local disease, the mechanisms by which PIM1 contributes to oncogenesis have not been fully elucidated. Here, we performed a direct, unbiased chemical genetic screen to identify PIM1 substrates in prostate cancer cells. The PIM1 substrates we identified were involved in a variety of oncogenic processes, and included N-Myc Downstream-Regulated Gene 1 (NDRG1), which has reported roles in suppressing cancer cell invasion and metastasis. NDRG1 is phosphorylated by PIM1 at serine 330 (pS330), and the level of NDRG1 pS330 is associated higher grade prostate tumors. We have shown that PIM1 phosphorylation of NDRG1 at S330 reduced its stability, nuclear localization, and interaction with AR, resulting in enhanced cell migration and invasion.

STAT1 is a modulator of the expression of frequently rearranged in advanced T-cell lymphomas 1 expression in U251 cells

Aberrant expression of frequently rearranged in advanced T-cell lymphomas 1 (FRAT1) contributes to poor prognosis in a number of carcinomas. However, its role in glioma remains controversial. In the present study, gene expression profiling was performed using Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO) functional enrichment and ingenuity pathway analysis (IPA) to evaluate the differential expression of genes and proteins in FRAT1 knockdown U251 glioma cells in comparison with the control. Western blot analysis was conducted to assess the expression levels of FRAT1 and STAT1. A total of 895 downregulated genes were identified in FRAT1-silenced U251 cells. The most enriched processes determined by GO and KEGG analysis of the 895 differentially expressed genes were associated with proliferation, migration and invasion. According to IPA, significant canonical pathways, including the interferon, hepatic fibrosis and Wnt/β-catenin signaling pathways, were identified to be the major enriched pathways. The elevated expression of STAT1 in U251 cells was validated. These results highlighted the regulatory role of FRAT1 in glioma cells with upregulated STAT1 expression.

Expression of STAT3-regulated genes in circulating CD4+ T cells discriminates rheumatoid arthritis independently of clinical parameters in early arthritis

OBJECTIVES

Dysregulated signal transduction and activator of transcription-3 (STAT3) signalling in CD4+ T cells has been proposed as an early pathophysiological event in RA. We sought further evidence for this observation, and to determine its clinical relevance.

METHODS

Microarray technology was used to measure gene expression in purified peripheral blood CD4+ T cells from treatment-naïve RA patients and disease controls newly recruited from an early arthritis clinic. Analysis focused on 12 previously proposed transcripts, and concurrent STAT3 pathway activation was determined in the same cells by flow cytometry. A pooled analysis of previous and current gene expression findings incorporated detailed clinical parameters and employed multivariate analysis.

RESULTS

In an independent cohort of 161 patients, expression of 11 of 12 proposed signature genes differed significantly between RA patients and controls, robustly validating the earlier findings. Differential regulation was most pronounced for the STAT3 target genes PIM1, BCL3 and SOCS3 (>1.3-fold difference; P < 0.005), each of whose expression correlated strongly with paired intracellular phospho-STAT3. In a meta-analysis of 279 patients the same three genes accounted for the majority of the signature's ability to discriminate RA patients, which was found to be independent of age, joint involvement or acute phase response.

CONCLUSION

The STAT3-mediated dysregulation of BCL3, SOCS3 and PIM1 in circulating CD4+ T cells is a discriminatory feature of early RA that occurs independently of acute phase response. The mechanistic and functional implications of this observation at a cellular level warrant clarification.

Therapeutic Implication of SOCS1 Modulation in the Treatment of Autoimmunity and Cancer

The suppressor of cytokine signaling (SOCS) family of intracellular proteins has a vital role in the regulation of the immune system and resolution of inflammatory cascades. SOCS1, also called STAT-induced STAT inhibitor (SSI) or JAK-binding protein (JAB), is a member of the SOCS family with actions ranging from immune modulation to cell cycle regulation. Knockout of SOCS1 leads to perinatal lethality in mice and increased vulnerability to cancer, while several SNPs associated with the SOCS1 gene have been implicated in human inflammation-mediated diseases. In this review, we describe the mechanism of action of SOCS1 and its potential therapeutic role in the prevention and treatment of autoimmunity and cancer. We also provide a brief outline of the other JAK inhibitors, both FDA-approved and under investigation.

PIM Kinase as an Executional Target in Cancer

PIM (proviral integration site for moloney murine leukemia virus) kinase plays a key role as an oncogene in various cancers including myeloma, leukemia, prostate and breast cancers. The aberrant expression and/or activation of PIM kinases in various cancers follow an isoform-specific pattern. While PIM1 is predominantly expressed in hematological and solid tumors, PIM2 and PIM3 are largely expressed in leukemia and solid tumors, respectively. All of PIM kinases cause transcriptional activation of genes involved in cell survival and cell cycle progression in cancer. A variety of pro-tumorigenic signaling molecules, such as MYC, p21^Cip1/Waf1/p27^kip1, CDC25, Notch1 and BAD have been identified as the downstream targets of PIM kinases. So far, three kinds of adenosine triphosphate-competitive PIM inhibitors, SGI-1776, AZD1208, and LGH447 have been in clinical trials for the treatment of acute myelogenous leukemia, prostate cancer, lymphoma, or multiple myeloma. This review sheds light on the signaling pathways involved in the PIM kinase regulation and current status of developing PIM kinase inhibitors as clinical success in combating human cancer.

Dynamic demethylation of the IL2RA promoter during in vitro CD4+ T cell activation in association with IL2RA expression

IL2RA, a subunit of the high affinity receptor for interleukin-2 (IL2), plays a crucial role in immune homeostasis. Notably, IL2RA expression is induced in CD4+ T cells in response to various stimuli and is constitutive in regulatory T cells (Tregs). We selected for our study 18 CpGs located within cognate regulatory regions of the IL2RA locus and characterized their methylation in naive, regulatory, and memory CD4+ T cells. We found that 5/18 CpGs (notably CpG + 3502) show dynamic, active demethylation during the in vitro activation of naive CD4+ T cells. Demethylation of these CpGs correlates with appearance of IL2RA protein at the cell surface. We found no influence of cis located SNP alleles upon CpG methylation. Treg cells show constitutive demethylation at all studied CpGs. Methylation of 9/18 CpGs, including CpG +3502, decreases with age. Our data thus identify CpG +3502 and a few other CpGs at the IL2RA locus as coordinated epigenetic regulators of IL2RA expression in CD4+ T cells. This may contribute to unravel how the IL2RA locus can be involved in immune physiology and pathology.

In glomerular cells of puromycin aminonucleoside nephrosis rats both phosphorylated and total STAT3 levels increased during proteinuria

Recent studies showed that JAK/STAT pathway plays role in glomerular damages. The fact that STAT3 could be activated also by oxidative stress make Puromycin Aminonucleoside (PAN) Nephrosis model very appropriate for examination of STAT3 expression changes in glomerular pathology. Along with a control group, three PAN groups sacrificed on different days were formed by the i.p. injection of PAN for 5 consecutive days. Throughout the experiment, 24-hour-urines were collected on specific days and proteinuria levels were monitored. At the end of the experiments, tissue specimens were stained immunohistochemically for both total and phosphorylated STAT3 and evaluated subjectively. They were also examined ultrastructurally in transmission electron microscope. The proteinuria levels did not increase significantly on 5th day but showed a dramatic increase on 10th and 15th days. On 20th and 25th days, urinary protein levels gradually decreased. Ultrastructural examinations showed glomerular damages such as significant decrease in slit pore number, a significant gradual increase in glomerular basement membrane thickness and podocyte hypertrophy on 5th and 15th days; besides significant increase in mesangial matrix. The first significant increases in phosphorylated and total STAT3 levels occurred in 5th day and 15th day groups respectively. These increases diminished in 25th day group. Regarding all the findings, it was deduced that STAT3 is one of the active factors in glomerular pathologies.

HOXA9 Cooperates with Activated JAK/STAT Signaling to Drive Leukemia Development

Leukemia is caused by the accumulation of multiple genomic lesions in hematopoietic precursor cells. However, how these events cooperate during oncogenic transformation remains poorly understood. We studied the cooperation between activated JAK3/STAT5 signaling and HOXA9 overexpression, two events identified as significantly co-occurring in T-cell acute lymphoblastic leukemia. Expression of mutant JAK3 and HOXA9 led to a rapid development of leukemia originating from multipotent or lymphoid-committed progenitors, with a significant decrease in disease latency compared with JAK3 or HOXA9 alone. Integrated RNA sequencing, chromatin immunoprecipitation sequencing, and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) revealed that STAT5 and HOXA9 have co-occupancy across the genome, resulting in enhanced STAT5 transcriptional activity and ectopic activation of FOS/JUN (AP1). Our data suggest that oncogenic transcription factors such as HOXA9 provide a fertile ground for specific signaling pathways to thrive, explaining why JAK/STAT pathway mutations accumulate in HOXA9-expressing cells.Significance: The mechanism of oncogene cooperation in cancer development remains poorly characterized. In this study, we model the cooperation between activated JAK/STAT signaling and ectopic HOXA9 expression during T-cell leukemia development. We identify a direct cooperation between STAT5 and HOXA9 at the transcriptional level and identify PIM1 kinase as a possible drug target in mutant JAK/STAT/HOXA9-positive leukemia cases. Cancer Discov; 8(5); 616-31. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 517.

Immunosenescence: the Role of Aging in the Predisposition to Neuro-Infectious Complications Arising from the Treatment of Multiple Sclerosis

PURPOSE OF REVIEW

This review highlights some of the important changes in the immune system that occur in the process of normal aging. Immunosenescence as a concept is directly relevant to the world of neuro-inflammation, as it may be a contributing factor to the risks associated with some of the current immunosuppressive and immunomodulatory therapies used in treating multiple sclerosis (MS) and other inflammatory disorders.

RECENT FINDINGS

Profound qualitative and quantitative changes occur in the adaptive and innate immunity compartments during aging. These changes may explain why patients of older age are at an increased risk of infections and infection-associated mortality. Immunosenescence-associated changes may be additive or synergistic with the effects produced by immunomodulatory and immunosuppressive medications. Clinicians should exercise a high level of vigilance in monitoring the risk of infections in older patients on these treatments.

PIM Kinases Are a Potential Prognostic Biomarker and Therapeutic Target in Neuroblastoma

The majority of high-risk neuroblastoma patients are refractory to, or relapse on, current treatment regimens, resulting in 5-year survival rates of less than 50%. This emphasizes the urgent need to identify novel therapeutic targets. Here, we report that high PIM kinase expression is correlated with poor overall survival. Treatment of neuroblastoma cell lines with the pan-PIM inhibitors AZD1208 or PIM-447 suppressed proliferation through inhibition of mTOR signaling. In a panel of neuroblastoma cell lines, we observed a marked binary response to PIM inhibition, suggesting that specific genetic lesions control responses to PIM inhibition. Using a genome-wide CRISPR-Cas9 genetic screen, we identified NF1 loss as the major resistance mechanism to PIM kinase inhibitors. Treatment with AZD1208 impaired the growth of NF1 wild-type xenografts, while NF1 knockout cells were insensitive. Thus, our data indicate that PIM inhibition may be a novel targeted therapy in NF1 wild-type neuroblastoma. Mol Cancer Ther; 17(4); 849-57. ©2018 AACR.

Intrinsic resistance to PIM kinase inhibition in AML through p38α-mediated feedback activation of mTOR signaling

Although conventional therapies for acute myeloid leukemia (AML) and diffuse large B-cell lymphoma (DLBCL) are effective in inducing remission, many patients relapse upon treatment. Hence, there is an urgent need for novel therapies. PIM kinases are often overexpressed in AML and DLBCL and are therefore an attractive therapeutic target. However, in vitro experiments have demonstrated that intrinsic resistance to PIM inhibition is common. It is therefore likely that only a minority of patients will benefit from single agent PIM inhibitor treatment. In this study, we performed an shRNA-based genetic screen to identify kinases whose suppression is synergistic with PIM inhibition. Here, we report that suppression of p38α (MAPK14) is synthetic lethal with the PIM kinase inhibitor AZD1208. PIM inhibition elevates reactive oxygen species (ROS) levels, which subsequently activates p38α and downstream AKT/mTOR signaling. We found that p38α inhibitors sensitize hematological tumor cell lines to AZD1208 treatment in vitro and in vivo. These results were validated in ex vivo patient-derived AML cells. Our findings provide mechanistic and translational evidence supporting the rationale to test a combination of p38α and PIM inhibitors in clinical trials for AML and DLBCL.

mTORC1 suppresses PIM3 expression via miR-33 encoded by the SREBP loci

The mechanistic target of rapamycin complex 1 (mTORC1) is a central regulator of cell growth that is often aberrantly activated in cancer. However, mTORC1 inhibitors, such as rapamycin, have limited effectiveness as single agent cancer therapies, with feedback mechanisms inherent to the signaling network thought to diminish the anti-tumor effects of mTORC1 inhibition. Here, we identify the protein kinase and proto-oncogene PIM3 as being repressed downstream of mTORC1 signaling. PIM3 expression is suppressed in cells with loss of the tuberous sclerosis complex (TSC) tumor suppressors, which exhibit growth factor-independent activation of mTORC1, and in the mouse liver upon feeding-induced activation of mTORC1. Inhibition of mTORC1 with rapamycin induces PIM3 transcript and protein levels in a variety of settings. Suppression of PIM3 involves the sterol regulatory element-binding (SREBP) transcription factors SREBP1 and 2, whose activation and mRNA expression are stimulated by mTORC1 signaling. We find that PIM3 repression is mediated by miR-33, an intronic microRNA encoded within the SREBP loci, the expression of which is decreased with rapamycin. These results demonstrate that PIM3 is induced upon mTORC1 inhibition, with potential implications for the effects of mTORC1 inhibitors in TSC, cancers, and the many other disease settings influenced by aberrant mTORC1 signaling.

Role of cellular metabolism in regulating type I interferon responses: Implications for tumour immunology and treatment

Type I interferons (IFN) are increasingly recognized for their role in regulating anti-tumour immune responses. However, chronic activation of these pathways can result in immunosuppression and has been linked to poor responses to genotoxic and radiotoxic therapies. Emerging evidence suggests energy, lipid and amino acid metabolism play an important role in regulating and fine tuning type I IFN responses. Further, dysregulation of these processes has been implicated in the pathogenesis of chronic viral infections and autoimmune disorders. Systematic evaluation of these interrelationships in cancer models and patients may have important implications for the development of targeted IFN based anti-cancer therapeutics with minimal toxicity and limited off target effects.

PIM1: a promising target in patients with triple-negative breast cancer

Triple-negative breast cancers (TNBCs) have poor prognosis, and chemotherapy remains the mainstay of therapy because of lack of discovered possible target. MYC were found overexpressed in TNBCs compared with other subtypes and especially in those resistant to chemotherapy, but the inhibition has been challenging to achieve. Recently, the cooperation of PIM1 and MYC was identified involved in cell proliferation, migration and apoptosis of TNBCs, which has been reported in hematological malignancy and prostatic cancer. Inhibition of PIM1 can promote the apoptosis of tumor cells and enhance sensitivity to chemotherapy. Notably, PIM1-null mice develop normally and are fertile, suggesting the side effects can be tolerated. Thus, PIM1 may be a promising target in TNBCs and further investigation, both in vivo and in vitro, needs to be carried out.

Expression of PIM kinases in Reed-Sternberg cells fosters immune privilege and tumor cell survival in Hodgkin lymphoma

Reed-Sternberg (RS) cells of classical Hodgkin lymphoma (cHL) express multiple immunoregulatory proteins that shape the cHL microenvironment and allow tumor cells to evade immune surveillance. Expression of certain immunoregulatory proteins is modulated by prosurvival transcription factors, such as NFκB and STATs. Because these factors also induce expression of the oncogenic PIM1/2/3 serine/threonine kinases, and as PIMs modulate transcriptional activity of NFκB and STATs, we hypothesized that these kinases support RS cell survival and foster their immune privilege. Here, we investigated PIM1/2/3 expression in cHL and assessed their role in developing RS cell immune privilege and survival. PIM1/2/3 were ubiquitously expressed in primary and cultured RS cells, and their expression was driven by JAK-STAT and NFκB activity. Genetic or chemical PIM inhibition with a newly developed pan-PIM inhibitor, SEL24-B489, induced RS cell apoptosis. PIM inhibition decreased cap-dependent protein translation, blocked JAK-STAT signaling, and markedly attenuated NFκB-dependent gene expression. In a cHL xenograft model, SEL24-B489 delayed tumor growth by 95.8% (P = .0002). Furthermore, SEL24-B489 decreased the expression of multiple molecules engaged in developing the immunosuppressive microenvironment, including galectin-1 and PD-L1/2. In coculture experiments, T cells incubated with SEL24-B489-treated RS cells exhibited higher expression of activation markers than T cells coincubated with control RS cells. Taken together, our data indicate that PIM kinases in cHL exhibit pleiotropic effects, orchestrating tumor immune escape and supporting RS cell survival. Inhibition of PIM kinases decreases RS cell viability and disrupts signaling circuits that link these cells with their niches. Thus, PIM kinases are promising therapeutic targets in cHL.

Signalome-wide assessment of host cell response to hepatitis C virus

Host cell signalling during infection with intracellular pathogens remains poorly understood. Here we report on the use of antibody microarray technology to detect variations in the expression levels and phosphorylation status of host cell signalling proteins during hepatitis C virus (HCV) replication. Following transfection with HCV RNA, the JNK and NF-κB pathways are suppressed, while the JAK/STAT5 pathway is activated; furthermore, components of the apoptosis and cell cycle control machineries are affected in the expression and/or phosphorylation status. RNAi-based hit validation identifies components of the JAK/STAT, NF-κB, MAPK and calcium-induced pathways as modulators of HCV replication. Selective chemical inhibition of one of the identified targets, the JNK activator kinase MAP4K2, does impair HCV replication. Thus this study provides a comprehensive picture of host cell pathway mobilization by HCV and uncovers potential therapeutic targets. The strategy of identifying targets for anti-infective intervention within the host cell signalome can be applied to any intracellular pathogen.

Development of antiviral strategies depends on an understanding of virus–host interactions. Here, using HCV, Haqshenas et al. show that antibody microarray combined with a targeted siRNA screen can be a powerful tool to identify cellular signalling pathways that are important for virus replication.

Type 1 Interferon in the Human Intestine-A Co-ordinator of the Immune Response to the Microbiota

The human gut is in constant complex interaction with the external environment. Although much is understood about the composition and function of the microbiota, much remains to be learnt about the mechanisms by which these organisms interact with the immune system in health and disease. Type 1 interferon (T1IFN), a ubiquitous and pleiotropic family of cytokines, is a critical mediator of the response to viral, bacterial, and other antigens sampled in the intestine. Although inflammation is enhanced in mouse model of colitis when T1IFN signaling is lost, the action of T1IFN is context specific and can be pro- or anti-inflammatory. In humans, T1IFN has been used to treat inflammatory diseases, including multiple sclerosis and inflammatory bowel disease but intestinal inflammation can also develop after the administration of T1IFN. Recent findings indicate that "tonic" or "endogenous" T1IFN, induced by signals from the commensal microbiota, modulates the local signaling environment to prime the intestinal mucosal immune system to determine later responses to pathogens and commensal organisms. This review will summarize the complex immunological effects of T1IFN and recent the role of T1IFN as a mediator between the microbiota and the mucosal immune system, highlighting human data wherever possible. It will discuss what we can learn from clinical experiences with T1IFN and how the T1IFN pathway may be manipulated in the future to maintain mucosal homeostasis.

Type I Interferons Modulate CD8+ T Cell Immunity to mRNA Vaccines

mRNA vaccines have emerged as potent tools to elicit antitumor T cell immunity. They are characterized by a strong induction of type I interferons (IFNs), potent inflammatory cytokines affecting T cell differentiation and survival. Recent reports have attributed opposing roles for type I IFNs in modulating CD8+ T cell immunity to mRNA vaccines, from profoundly stimulatory to strongly inhibitory. The mechanisms behind this duality are unclear. Disentangling the factors governing the beneficial or detrimental impact of type I IFNs on CD8+ T cell responses is vital to the design of mRNA vaccines of increased potency. In light of recent advancements regarding the complex role of type I IFNs in regulating CD8+ T cell immunity to infectious diseases, we posit that the dual outcome of type I IFNs on CD8+ T cell responses to mRNA vaccination is determined by the timing and intensity of type I IFN induction relative to T cell receptor (TCR) activation.

A CgIFNLP receptor from Crassostrea gigas and its activation of the related genes in human JAK/STAT signaling pathway

Interferon is a highly pleiotropic cytokine, once binding to its receptors, can activate JAK kinases and STAT transcription factors to initiate the transcription of genes downstream from interferon-stimulated response elements. In the present study, a cytokine receptor-like 3 molecule was selected and cloned from oyster Crassostrea gigas, which contained a fibronectin type III domain (designed CgIFNR-3). The expression pattern of CgIFNR-3 mRNA was detected in all the tested tissues including mantle, gills, hepatopancreas, muscle, and hemocytes, with the highest expression level in hemocytes. After poly (I: C) stimulation, the expression level of CgIFNR-3 in hemocytes was observed to significantly increase at 3 h (13.06-fold, p < 0.01). CgIFNR-3 was indicated to interact with CgIFNLP by in vitro GST pull-down assay, and to activate the expression of transcription factors including ISRE, STAT3 and GAS, in human Janus kinase signal transducer and activator of transcription (JAK/STAT) pathway after co-transfection in HEK-293T cells in the reporter luciferase activity assay. These results suggested that CgIFNR-3 could bind to CgIFNLP as an interferon receptor and participate in the activation of JAK/STAT pathway in human, which will benefit for intensive studies of interferon signaling pathway in mollusc.

Developmental stage-specific effects of Pim-1 dysregulation on murine bone marrow B cell development

Background

The serine threonine kinase Pim-1 has documented roles in hematopoietic progenitor and B cell precursor proliferation and survival. Pim-1 is a molecular target of the transcription factor Hoxa9. Previous studies showed that Pim-1 deficiency phenocopied the hematopoietic progenitor defect in hoxa9-/- mice and forced expression of Pim-1 normalized the in vitro proliferation defect inherent to hoxa9-/- hematopoietic progenitors. Pim-1 is induced by cytokine signaling, including the early lymphoid/B lineage regulators Flt3 and IL-7, and expression levels were shown to influence the size of the B cell compartment in bone marrow (BM).

Results

In this study, we sought to determine if transgenic expression of Pim-1, driven by the immunoglobulin enhancer, Eμ, was sufficient to rescue the lymphoid/B cell precursor defect in hoxa9 or flt3-ligand (flt3l) deficient mice. Unexpectedly, expression of Eμ − Pim1 exacerbated lymphoid progenitor deficiencies in flt3l-/-, and to a lesser extent, hoxa9-/- mice. Furthermore, Eμ − Pim1 expression alone reduced early myeloid and lymphoid, but not erythroid, progenitors. In contrast, Pim-1 deficiency had no significant effect on early lymphoid/B cell development through the Pre-Pro-B cell stage, but caused a significant reduction in IgM⁻ B cell precursors. Importantly, loss of Pim-1 did not phenocopy hoxa9- or flt3l-deficiency on the lymphoid/early B cell progenitor pools.

Conclusions

These experimental findings demonstrate that Pim-1 overexpression has developmental-stage-specific effects on B lymphopoiesis and myelopoiesis. Importantly, these suggest that Pim-1 deficiency does not contribute significantly to the early lymphoid/B cell developmental deficiency in hoxa9-/- or flt3l-/- mice.

Identification of quinones as novel PIM1 kinase inhibitors

PIM1 is a proto-oncogene encoding the serine/threonine PIM1 kinase. PIM1 kinase plays important roles in regulating aspects of cell cycle progression, apoptosis resistance, and has been implicated in the development of such malignancies as prostate cancer and acute myeloid leukemia among others. Knockout of PIM1 kinase in mice has been shown to be non-lethal without any obvious phenotypic changes, making it an attractive therapeutic target. Our investigation of anthraquinones as kinase inhibitors revealed a series of quinone analogs showing high selectivity for inhibition of the PIM kinases. Molecular modeling studies were used to identify key interactions and binding poses of these compounds within the PIM1 binding pocket. Compounds 1, 4, 7 and 9 inhibited the growth of DU-145 prostate cancer cell lines with a potency of 8.21μM, 4.06μM, 3.21μM and 2.02μM.

Restoration of normal embryogenesis by mitochondrial supplementation in pig oocytes exhibiting mitochondrial DNA deficiency

An increasing number of women fail to achieve pregnancy due to either failed fertilization or embryo arrest during preimplantation development. This often results from decreased oocyte quality. Indeed, reduced mitochondrial DNA copy number (mitochondrial DNA deficiency) may disrupt oocyte quality in some women. To overcome mitochondrial DNA deficiency, whilst maintaining genetic identity, we supplemented pig oocytes selected for mitochondrial DNA deficiency, reduced cytoplasmic maturation and lower developmental competence, with autologous populations of mitochondrial isolate at fertilization. Supplementation increased development to blastocyst, the final stage of preimplantation development, and promoted mitochondrial DNA replication prior to embryonic genome activation in mitochondrial DNA deficient oocytes but not in oocytes with normal levels of mitochondrial DNA. Blastocysts exhibited transcriptome profiles more closely resembling those of blastocysts from developmentally competent oocytes. Furthermore, mitochondrial supplementation reduced gene expression patterns associated with metabolic disorders that were identified in blastocysts from mitochondrial DNA deficient oocytes. These results demonstrate the importance of the oocyte’s mitochondrial DNA investment in fertilization outcome and subsequent embryo development to mitochondrial DNA deficient oocytes.

Type I interferons in viral control and immune regulation

Type 1 interferons (IFN-I) exert pleiotropic biological effects during viral infections, all which contribute to balancing virus control and immune pathology. Despite extensive antiviral functions that subdue virus replication, recent studies demonstrate pathogenic and pro-viral roles for IFN-I signaling during acute and persistent virus infection. IFN-I signaling can promote morbidity and mortality through induction of aberrant inflammatory responses during acute viral infection. In contrast, IFN-I signaling during persistent viral infection supports immune suppression, lymphoid tissue disorganization and CD4 T cell dysfunction. Systematic characterization of the cellular populations and intricacies of IFN-I signaling that promote pathology or immune suppression during acute and persistent viral infections, respectively, should inform the development of treatments and modalities to control viral associated pathologies.

Targeting the Janus-activated kinase-2-STAT3 signalling pathway in pancreatic cancer using the HSP90 inhibitor ganetespib

BACKGROUND

Pancreatic cancer (PC) is an aggressive malignancy characterised by chemoresistance. HSP90 is important for stabilisation of proteins, cell signalling and malignant growth. We hypothesised that ganetespib, an HSP90 inhibitor, can inhibit PC cell growth by interfering with multiple signalling cascades, including the Janus-activated kinase (JAK)-STAT pathway, and act synergistically with chemotherapeutic drugs.

METHODS

The effects of ganetespib were evaluated in ASPC-1, HPAC, MIA PaCA-2 and PANC-1 cell lines using a cell proliferation assay. Effects on the expression of phosphoinositide 3-kinase (PI3K)/AKT, mitogen-activated protein kinase (MAPK) and JAK-STAT pathways were examined by Western blot. JAK2 and STAT3 were knocked down by transient transfection with JAK2 or STAT3 small interfering RNA. ASPC-1 and HPAC cell lines were tested for sensitivity to ganetespib, 5-fluorouracil/oxaliplatin, and gemcitabine/paclitaxel, alone and in combination, using an in vivo tumour xenograft model.

RESULTS

Ganetespib significantly decreased cell proliferation in all tested PC cell lines. Ganetespib decreased the activation of extracellular signal-related kinase (ERK), PI3K/AKT, and c-Jun NH2-terminal kinase (JNK) signalling molecules and diminished the activation of STAT3 in an additive manner with isolated downregulation of JAK2 expression. In animal models, ganetespib potentiated the effects of 5-fluouracil/oxaliplatin and gemcitabine/paclitaxel, as measured by tumour volume. Western blot analysis from tumours removed from animals confirmed the effects of ganetespib on PI3K/AKT, ERK and JNK pathways.

CONCLUSIONS

Ganetespib inhibits the growth of PC cells, an effect associated with downregulation of signalling through the JAK2-STAT3, PI3K/AKT and MAPK pathways. This provides preclinical proof-of-principle that ganetespib enhances the activity of chemotherapeutic agents and warrants further evaluation in PC clinical trials.

IFN-γ Priming Effects on the Maintenance of Effector Memory CD4(+) T Cells and on Phagocyte Function: Evidences from Infectious Diseases

Although it has been established that effector memory CD4⁺ T cells play an important role in the protective immunity against chronic infections, little is known about the exact mechanisms responsible for their functioning and maintenance, as well as their effects on innate immune cells. Here we review recent data on the role of IFN-γ priming as a mechanism affecting both innate immune cells and effector memory CD4⁺ T cells. Suboptimal concentrations of IFN-γ are seemingly crucial for the optimization of innate immune cell functions (including phagocytosis and destruction of reminiscent pathogens), as well as for the survival and functioning of effector memory CD4⁺ T cells. Thus, IFN-γ priming can thus be considered an important bridge between innate and adaptive immunity.

Age-Associated Failure To Adjust Type I IFN Receptor Signaling Thresholds after T Cell Activation

With increasing age, naive CD4 T cells acquire intrinsic defects that compromise their ability to respond and differentiate. Type I IFNs, pervasive constituents of the environment in which adaptive immune responses occur, are known to regulate T cell differentiation and survival. Activated naive CD4 T cells from older individuals have reduced responses to type I IFN, a defect that develops during activation and that is not observed in quiescent naive CD4 T cells. Naive CD4 T cells from young adults upregulate the expression of STAT1 and STAT5 after activation, lowering their threshold to respond to type I IFN stimulation. The heightened STAT signaling is critical to maintain the expression of CD69 that regulates lymphocyte egress and the ability to produce IL-2 and to survive. Although activation of T cells from older adults also induces transcription of STAT1 and STAT5, failure to exclude SHP-1 from the signaling complex blunts their type I IFN response. In summary, our data show that type I IFN signaling thresholds in naive CD4 T cells after activation are dynamically regulated to respond to environmental cues for clonal expansion and memory cell differentiation. Naive CD4 T cells from older adults have a defect in this threshold calibration. Restoring their ability to respond to type I IFN emerges as a promising target to restore T cell responses and to improve the induction of T cell memory.

Immunotherapy in acute myeloid leukemia

Despite the remarkable progress made in some leukemias such as CML and CLL, cytotoxic treatment for AML remains essentially unchanged over the last 4 decades. Several lines of evidence, including the graft versus leukemia effect associated with allogeneic hematopoietic stem cell transplantation (HSCT), suggest that immunotherapy is an active modality in AML. Given the lack of progress for chemotherapy in this disease, many novel immunologic treatment approaches have been explored. The goals of non-transplant-based immune approaches have largely consisted of the stimulation or restoration of endogenous immune responses or the targeting of specific tumor antigens by immune cells. These strategies have been associated with less toxicity than allogeneic HSCT but typically have inferior efficacy. Allogeneic HSCT exploits major and minor histocompatibility differences between the donor and recipient in order to recognize and eradicate malignancy. With the recognition that the immune system itself provides a basis for treating AML, immunotherapy continues to be an attractive modality to exploit in the treatment of this disease.

PIM kinase (and Akt) biology and signaling in tumors

The initiation and progression of human cancer is frequently linked to the uncontrolled activation of survival kinases. Two such pro-survival kinases that are commonly amplified in cancer are PIM and Akt. These oncogenic proteins are serine/threonine kinases that regulate tumorigenesis by phosphorylating substrates that control the cell cycle, cellular metabolism, proliferation, and survival. Growing evidence suggests that cross-talk exists between the PIM and Akt kinases, indicating that they control partially overlapping survival signaling pathways that are critical to the initiation, progression, and metastatic spread of many types of cancer. The PI3K/Akt signaling pathway is activated in many human tumors, and it is well established as a promising anticancer target. Likewise, based on the role of PIM kinases in normal and tumor tissues, it is clear that this family of kinases represents an interesting target for anticancer therapy. Pharmacological inhibition of PIM has the potential to significantly influence the efficacy of standard and targeted therapies. This review focuses on the regulation of PIM kinases, their role in tumorigenesis, and the biological impact of their interaction with the Akt signaling pathway on the efficacy of cancer therapy.

Targeting Pim kinases for cancer treatment: opportunities and challenges

Pim oncogenes are highly expressed in many types of hematological and solid cancers. Pim kinases regulate the network of signaling pathways that are critical for tumorigenesis and development, making Pim kinases the attractive drug targets. Currently, two approaches have been employed in designing Pim kinase inhibitors: ATP-mimetics and non-ATP mimetics; but all target the ATP-binding pocket and are ATP-competitive. In this review, we summarize the current progress in understanding the Pim-related structure and biology, and provide insights into the binding modes of some prototypical Pim-1 inhibitors. The challenges as well as opportunities are highlighted for development of Pim kinase inhibitors as potential anticancer agents.

ETV6/ARG oncoprotein confers autonomous cell growth by enhancing c-Myc expression via signal transducer and activator of transcription 5 activation in the acute promyelocytic leukemia cell line HT93A

We investigated the role of ETV6/ARG fusion gene by exposing the HT93A cell line to nilotinib. HT93A cells were cultured with or without nilotinib±50 ng/mL of granulocyte colony-stimulating factor (G-CSF). Nilotinib treatment inhibited cell growth by increasing the percentage of cells in G0/G1 phase through the decrease of phosphorylated signal transducer and activator of transcription 3 (STAT3) (Y705), STAT5 (Y694) and c-Myc expression. After stimulation with G-CSF, STAT5 but not STAT3 was significantly phosphorylated in both nilotinib-treated and untreated cells. Moreover, combination therapy with nilotinib and G-CSF returned the expression level of c-Myc, cell growth and cell cycle distribution to the control level. These findings suggest that the ETV6/ARG oncoprotein contributes to autonomous cell growth by compensating for the requirement of growth factor through activating STAT5 signaling, which leads to the up-regulation of c-Myc. Our data suggest that ETV6/ARG oncoprotein is a potential target in the treatment of leukemia.

Noncanonical NF-κB activation mediates STAT3-stimulated IDO upregulation in myeloid-derived suppressor cells in breast cancer

Immunotherapy for cancer treatment is achieved through the activation of competent immune effector cells and the inhibition of immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs). Although MDSCs have been shown to contribute to breast cancer development, the mechanism underlying MDSC-mediated immunosuppression is unclear. We have identified a poorly differentiated MDSC subset in breast cancer-suppressing T cell function through STAT3-dependent IDO upregulation. In this study we investigated the mechanisms underlying aberrant expression of IDO in MDSCs. MDSCs were induced by coculturing human CD33(+) myeloid progenitors with MDA-MB-231 breast cancer cells. Increased STAT3 activation in MDSCs was correlated with activation of the noncanonical NF-κB pathway, including increased NF-κB-inducing kinase (NIK) protein level, phosphorylation of cytoplasmic inhibitor of NF-κB kinase α and p100, and RelB-p52 nuclear translocation. Blocking STAT3 activation with the small molecule inhibitor JSI-124 significantly inhibited the accumulation of NIK and IDO expression in MDSCs. Knockdown of NIK in MDSCs suppressed IDO expression but not STAT3 activation. RelB-p52 dimers were found to directly bind to the IDO promoter, leading to IDO expression in MDSCs. IL-6 was found to stimulate STAT3-dependent, NF-κB-mediated IDO upregulation in MDSCs. Furthermore, significant positive correlation between the numbers of pSTAT3(+) MDSCs, IDO(+) MDSCs, and NIK(+) MDSCs was observed in human breast cancers. These results demonstrate a STAT3/NF-κB/IDO pathway in breast cancer-derived MDSCs, which provides insight into understanding immunosuppressive mechanisms of MDSCs in breast cancer.