Dendritic Cells in Shaping Anti-Tumor T Cell Response.

Among professional antigen-presenting cells, dendritic cells (DCs) orchestrate innate and adaptive immunity and play a pivotal role in anti-tumor immunity. DCs are a heterogeneous population with varying functions in the tumor microenvironment (TME). Tumor-associated DCs differentiate developmentally and functionally into three main subsets: conventional DCs (cDCs), plasmacytoid DCs (pDCs), and monocyte-derived DCs (MoDCs). There are two major subsets of cDCs in TME, cDC1 and cDC2. cDC1 is critical for cross-presenting tumor antigens to activate cytotoxic CD8+ T cells and is also required for priming earlier CD4+ T cells in certain solid tumors. cDC2 is vital for priming anti-tumor CD4+ T cells in multiple tumor models. pDC is a unique subset of DCs and produces type I IFN through TLR7 and TLR9. Studies have shown that pDCs are related to immunosuppression in the TME through the secretion of immunosuppressive cytokines and by promoting regulatory T cells. MoDCs differentiate separately from monocytes in response to inflammatory cues and infection. Also, MoDCs can cross-prime CD8+ T cells. In this review, we summarize the subsets and functions of DCs. We also discuss the role of different DC subsets in shaping T cell immunity in TME and targeting DCs for potential immunotherapeutic benefits against cancer.

Effects of long-term exposure to MST-312 on lung cancer cells tumorigenesis: Role of SHH/GLI-1 axis.

Replicative immortality is a key feature of cancer cells and it is maintained by the expression of telomerase, a promising target of novel therapies. Long-term telomerase inhibition can induce resistance, but the mechanisms underlying this process remain unclear. The Sonic hedgehog pathway (SHH) is an embryogenic pathway involved in tumorigenesis and modulates the transcription of telomerase. We evaluated the effects of long-term treatment of the telomerase inhibitor MST-312 in morphology, proliferation, resistance, and in the SHH pathway molecules expression levels in lung cancer cells. Cells treated for 12 weeks with MST-312 showed changes in morphology, such as spindle-shaped cells, and a shift in the distribution of F-ACTIN from cortical to diffuse. Treatment also significantly reduced cells' efficiency to form spheroids and their clonogenic potential, independently of the cell cycle and telomeric DNA content. Moreover, GLI-1 expression levels were significantly reduced after 12 weeks of MST-312 treatment, indicating a possible inhibition of this signaling axis in the SHH pathway, without hindering NANOG and OCT4 expression. Here, we described a novel implication of long-term treatment with MST-312 functionally and molecularly, shedding new light on the molecular mechanisms of this drug in vitro.

Differentiation of Memory CD8 T Cells Unravel Gene Expression Pattern Common to Effector and Memory Precursors.

Long-term immunological protection relies on the differentiation and maintenance of memory lymphocytes. Since the knowledge of memory generation has been centered on in vivo models of infection, there are obstacles to deep molecular analysis of differentiating subsets. Here we defined a novel in vitro CD8 T cell activation and culture regimen using low TCR engagement and cytokines to generate differentiated cells consistent with central memory-like cells, as shown by surface phenotype, gene expression profile and lack of cytotoxic function after challenge. Our results showed an effector signature expressed by in vitro memory precursors and their plasticity under specific conditions. Moreover, memory CD8 T cells conferred long-term protection against bacterial infection and slowed in vivo tumor growth more efficiently than effector cells. This model may allow further understanding of CD8 T cell memory molecular differentiation subsets and be suited for generating cells to be used for immunotherapy.

The pterocarpanquinone LQB­118 compound induces apoptosis of cytarabine­resistant acute myeloid leukemia cells.

Acute myeloid leukemia (AML) is a complex hematological disorder characterized by blockage of differentiation and high proliferation rates of myeloid progenitors. Anthracycline and cytarabine­based therapy has remained the standard treatment for AML over the last four decades. Although this treatment strategy has increased survival rates, patients often develop resistance to these drugs. Despite efforts to understand the mechanisms underlying cytarabine resistance, there have been few advances in the field. The present study developed an in vitro AML cell line model resistant to cytarabine (HL­60R), and identified chromosomal aberrations by karyotype evaluation and potential molecular mechanisms underlying chemoresistance. Cytarabine decreased cell viability, as determined by MTT assay, and induced cell death and cell cycle arrest in the parental HL­60 cell line, as revealed by Annexin V/propidium iodide (PI) staining and PI DNA incorporation, respectively, whereas no change was observed in the HL­60R cell line. In addition, the HL­60R cell line exhibited a higher tumorigenic capacity in vivo compared with the parental cell line. Notably, no reduction in tumor volume was detected in mice treated with cytarabine and inoculated with HL­60R cells. In addition, western blotting revealed that the protein expression levels of Bcl­2, X­linked inhibitor of apoptosis protein (XIAP) and c­Myc were upregulated in HL­60R cells compared with those in HL­60 cells, along with predominant nuclear localization of the p50 and p65 subunits of NF­κB in HL­60R cells. Furthermore, the antitumor effect of LQB­118 pterocarpanquinone was investigated; this compound induced apoptosis, a reduction in cell viability and a decrease in XIAP expression in cytarabine­resistant cells. Taken together, these data indicated that acquired cytarabine resistance in AML was a multifactorial process, involving chromosomal aberrations, and differential expression of apoptosis and cell proliferation signaling pathways. Furthermore, LQB­118 could be a potential alternative therapeutic approach to treat cytarabine­resistant leukemia cells.

Zika virus oncolytic activity requires CD8+ T cells and is boosted by immune checkpoint blockade.

Glioblastoma multiforme (GBM) is a fatal human cancer in part because GBM stem cells are resistant to therapy and recurrence is inevitable. Previously, we demonstrated Zika virus (ZIKV) targets GBM stem cells and prevents death of mice with gliomas. Here, we evaluated the immunological basis of ZIKV-mediated protection against GBM. Introduction of ZIKV into the brain tumor increased recruitment of CD8+ T and myeloid cells to the tumor microenvironment. CD8+ T cells were required for ZIKV-dependent tumor clearance because survival benefits were lost with CD8+ T cell depletion. Moreover, while anti-PD-1 antibody monotherapy moderately improved tumor survival, when coadministered with ZIKV, survival increased. ZIKV-mediated tumor clearance also resulted in durable protection against syngeneic tumor rechallenge, which also depended on CD8+ T cells. To address safety concerns, we generated an immune-sensitized ZIKV strain, which was effective alone or in combination with immunotherapy. Thus, oncolytic ZIKV treatment can be leveraged by immunotherapies, which may prompt combination treatment paradigms for adult patients with GBM.

Germinal Centre B Cell Functions and Lymphomagenesis: Circuits Involving MYC and MicroRNAs.

BACKGROUND: The transcription factor MYC regulates several biological cellular processes, and its target gene network comprises approximately 15% of all human genes, including microRNAs (miRNAs), that also contribute to MYC regulatory activity. Although miRNAs are emerging as key regulators of immune functions, the specific roles of miRNAs in the regulation/dysregulation of germinal centre B-cells and B-cell lymphomas are still being uncovered. The regulatory network that integrates MYC, target genes and miRNAs is a field of intense study, highlighting potential pathways to be explored in the context of future clinical approaches. METHODS: The scientific literature that is indexed in PUBMED was consulted for publications involving MYC and miRNAs with validated bioinformatics analyses or experimental protocols. Additionally, seminal studies on germinal centre B-cell functions and lymphomagenesis were reported. CONCLUSIONS: This review summarizes the interactions between MYC and miRNAs through regulatory loops and circuits involving target genes in germinal centre B-cell lymphomas with MYC alterations. Moreover, we provide an overview of the understanding of the regulatory networks between MYC and miRNAs, highlighting the potential implication of this approach for the comprehension of germinal centre B-cell lymphoma pathogenesis. Therefore, circuits involving MYC, target genes and miRNAs provide novel insight into lymphomagenesis that could be useful for new improved therapeutic strategies.

miR­29 promoter and enhancer methylation identified by pyrosequencing in Burkitt lymhoma cells: Interplay between MYC and miR­29 regulation.

Deregulation of microRNA expression plays a significant role in several cancer types including Burkitt lymphoma (BL). MicroRNA genes may be regulated through epigenetic mechanisms, such as specific histone modifications and/or DNA methylation of CpG islands in promoter regions, or by regions that are located next to microRNA genes. Given the regulatory role of MYC in miR­29 expression, methylation as an additional mechanism for miR­29 silencing was investigated. Methylation of miR­29a/b/c in BL tumour samples and BL cell lines (BL41 and Raji) was assessed by pyrosequencing assay. BL cells were treated with 5­aza­2'­deoxicitidine (decitabine) and evaluated for miR­29a/b/c expression and methylation status. MYC, DNMT1 and DNMT3B protein expression were accessed by western blotting. For Epstein­Barr virus (EBV) microRNA (miR)­BART6 inhibition, the cells were transiently transfected with anti­BART6­5p. BL tumour samples and BL cell lines presented miR­29a/b1 and miR­29b2/c genes methylated in CpG sites located in both the promoter and enhancer regions. The treatment of BL cells with decitabine reduced methylation, induced miR­29s expression and downregulated MYC protein levels in a dose­dependent manner. Notably, inhibition of EBV miR­BART6­5p combined with decitabine enhanced miR­29 expression in an EBV­BL cell line. In conclusion, the miR­29a/b1 and miR­29b2/c genes have methylated CpG sequences at promoter and enhancer regions that may contribute to the regulation of miR­29 expression in BL tumours. The present findings indicated interplay between MYC and miR­29 regulation, highlighting the potential role of EBV­miRNAs in miR­29 regulation for BL pathogenesis.

MiR-29 silencing modulates the expression of target genes related to proliferation, apoptosis and methylation in Burkitt lymphoma cells.

PURPOSE: Burkitt lymphoma (BL) is a B-cell lymphoma frequently diagnosed in children. It is characterized by MYC translocations, which lead to the constitutive expression of the MYC oncogene. MYC contributes to miR-29 repression through an E-box MYC binding site on the miR-29b-1/miR-29a promoter region. We evaluated the role of miR-29a/b/c and their predicted targets in BL pathogenesis. METHODS: Mature sequences of miR-29a/b/c were transfected to the BL cell lines BL41 and Raji, and evaluated for DNMT3B, MCL1, BIM, CDK6, AKT and TCL1 protein expression as well as for MCL-1 and CDK6 mRNA expression. BL cells were treated with 5-aza-2'-deoxycytidine (decitabine) and evaluated for miR29 expressions and methylation status. DNMT3B inhibition was performed by DNMT3B siRNA. RESULTS: Ectopic expression of miR-29s in BL cells decreased CDK6, DNMT3B, TCL1 and MCL-1 protein levels, but CDK6 and MCL-1 mRNA expression was unaffected by miR-29. Decitabine enhanced miR-29 expression levels and decreased CDK6 protein expression. Additionally, inhibition of DNMT3B by siRNA increased miR-29a/b expression. Notably, the miR-29a/b1 and miR-29b2/c promoter genes showed methylated CpG sequences that were demethylated after decitabine treatments. Furthermore, MYC-negative tumours had higher levels of miR-29 expression compared with MYC-translocated cases, suggesting that MYC regulates miR-29 in BL tumours. CONCLUSIONS: Our results suggest a significant role for miR-29s in BL pathogenesis in altering the expression of targets involved in critical cancer pathways, such as cell cycle control, apoptosis inhibition and DNA methylation. Moreover, methylation-mediated miR-29 epigenetic silencing may occur during BL development.

miR-17-92 cluster components analysis in Burkitt lymphoma: overexpression of miR-17 is associated with poor prognosis.

Burkitt lymphoma (BL) is an aggressive B cell lymphoma characterized by the reciprocal translocation of the c-Myc gene with immunoglobulin genes. Recently, MYC has been shown to maintain the neoplastic state via the miR-17-92 microRNA cluster that suppresses chromatin regulatory genes and the apoptosis regulator Bim. However, the expression and prognostic impact of miR-17-92 members in pediatric BL (pBL) are unknown. Therefore, we investigated miR-17, miR-19a, miR-19b, miR-20, and miR-92a expression and prognostic impact in a series of 41 pBL samples. In addition, Bim protein expression was evaluated and compared to miR-17, miR-19a, miR-19b, miR-20, and miR-92a levels and patient outcomes. The expression of miR-17-92 members was evaluated by qPCR and Bim protein by immunohistochemistry. Log-rank test was employed to assess prognostic impact. We found that upregulated expression of miR-17 and miR-20a correlates with lack of pro-apoptotic Bim expression. Patients bearing tumors with upregulated miR-17 displayed decreased overall survival (OS), and multivariate analysis revealed that miR-17 was a significant predictor of shortened OS. Using hairpin inhibitors, we showed that inhibition of miR-17 resulted in enhanced Bim expression in a BL cell line overexpressing the miR-17-92 cluster. Our results describe for the first time miR-17, miR-19a, miR-19b, miR-20a, and miR-92a expression profiles in pBL. The prognostic impact of miR-17 should be validated in a larger series, and may provide new therapeutic avenues in the era of anti-miRNA therapy research. Additional functional studies are further required to understand the specific role of miR-17-92 cluster members in BL.

Deregulation of DNMT1, DNMT3B and miR-29s in Burkitt lymphoma suggests novel contribution for disease pathogenesis.

Methylation of CpG islands in promoter gene regions is frequently observed in lymphomas. DNA methylation is established by DNA methyltransferases (DNMTs). DNMT1 maintains methylation patterns, while DNMT3A and DNMT3B are critical for de novo DNA methylation. Little is known about the expression of DNMTs in lymphomas. DNMT3A and 3B genes can be regulated post-transcriptionally by miR-29 family. Here, we demonstrated for the first time the overexpression of DNMT1 and DNMT3B in Burkitt lymphoma (BL) tumor samples (69% and 86%, respectively). Specifically, the treatment of two BL cell lines with the DNMT inhibitor 5-aza-dC decreased DNMT1 and DNMT3B protein levels and inhibited cell growth. Additionally, miR-29a, miR-29b and miR-29c levels were significantly decreased in the BL tumor samples. Besides, the ectopic expression of miR-29a, miR-29b and miR-29c reduced the DNMT3B expression and miR-29a and miR-29b lead to increase of p16(INK4a) mRNA expression. Altogether, our data suggest that deregulation of DNMT1, DNMT3B and miR29 may be involved in BL pathogenesis.

Novel thalidomide analogues from diamines inhibit pro-inflammatory cytokine production and CD80 expression while enhancing IL-10.

Thalidomide is used to treat a variety of diseases including erythema nodosum leprosum, an inflammatory complication of leprosy. However, this drug has severe teratogenic activity and novel thalidomide analogues might be used to treat diseases without this severe side effect. A series of diamine compounds containing two hydrolyzed phthalimide units were chosen as analogues of thalidomide and evaluated regarding their capacity to regulate the production of molecules involved in inflammatory responses. TNF-α, IL-12 and IL-10 production, and the expression of CD80 and CD86 were investigated in LPS plus IFN-γ-stimulated J774A.1 cells by ELISA and flow cytometry, respectively. The expression of TNF-α and IL-10 mRNA was analyzed by real time RT-PCR. TNF-α, IL-6, IFN-γ, CXCL9 and CXCL10 production by human peripheral blood mononuclear cells (PBMC) were evaluated by flow cytometry. Compounds 3, 6 and 9 greatly inhibited TNF-α and IL-12 production while enhancing IL-10. In addition, CD80 expression was inhibited, but not CD86. The compounds inhibited TNF-α production by PBMC more than thalidomide and also had an inhibitory effect on the production of IL-6, IFN-γ, CXCL9 and CXCL10. Levels of mRNA for TNF-α were reduced after treatment with the compounds, suggesting post- transcriptional effects. The compounds had no effect on cell viability. Our results indicate that the novel diamine compounds 3, 6 and 9 inhibit critical pro-inflammatory cytokines and stimulate IL-10, which make them attractive candidate drugs for the treatment of certain inflammatory conditions and cancer.

Immunomodulatory effects and improved prognosis of experimental autoimmune encephalomyelitis after O-tetradecanoyl-genistein treatment.

Experimental autoimmune encephalomyelitis (EAE) is a murine autoimmune disease used to study multiple sclerosis (MS), a human inflammatory demyelinating disease of the central nervous system. Genistein, an isoflavonoid phytoestrogenic compound found in soy, is known to reverse clinical signs of EAE. Although genistein has some potential in clinical application, it has some disadvantages related to its chemical structure, such as rapid in vivo metabolism and a fast decline in serum after oral administration. The present work investigates the treatment of EAE by using 7-O-tetradecanoyl-genistein (TDG), a more lipophilic analog of genistein obtained by esterification. The clinical course of EAE was investigated in C57Bl/6 mice immunized with myelin oligodendrocyte glycoprotein peptide (MOG)(35-55) in complete Freund's adjuvant supplemented with Mycobacterium tuberculosis H37RA. After 14 days of MOG immunization, mice were treated with TDG for seven days. Numbers of IL-17-producing cells and Foxp3 by CD4(+) T cells and CTLA-4 expression by CD3(+) T cells from brain were determined by flow cytometry. Levels of IL-6, IFN-γ and IL-10 were evaluated by ELISA. Brain sections were stained by hematoxylin and eosin method. The data obtained indicate that TDG treatment ameliorates the clinical signs of EAE, which correlates with a decrease of IL-17-producing cells and an increase in Foxp3(+)CD4(+) cells in the brain. TDG is also shown to enhance IL-10 production and CTLA-4 expression and to reduce IFN-γ and IL-6. Altogether, these findings suggest an immunomodulatory therapeutic role for TDG in EAE and multiple sclerosis.

Synthesis of lipophilic genistein derivatives and their regulation of IL-12 and TNF-α in activated J774A.1 cells.

Genistein modulates inflammatory responses in part by reducing the production of the pro-inflammatory cytokines IL-12, TNF-α, and nitric oxide, by activated macrophages in response to lipopolysaccharide stimulus. Previous studies have shown that synthetic lipophilic genistein glycosides were significantly more active than hydrophilic glycosides. The aims of this study were to synthesize and to evaluate the effect of novel lipophilic genistein derivatives on IL-12, TNF-α, and nitric oxide production by J774A.1 cells. The results show that the modification of genistein enables the generation of non-cytotoxic compounds with increased IL-12 inhibition. However, these derivatives failed to inhibit TNF-α. The nitric oxide production was notably inhibited by the monoester (2, 3) and monoether (6, 7) compounds in a dose-dependent manner.

Anti-mycobacterial treatment reduces high plasma levels of CXC-chemokines detected in active tuberculosis by cytometric bead array.

Chemokines recruit and activate leukocytes, assisting granuloma formation. Herein, we evaluated plasma chemokines in patients with active tuberculosis (ATB) and after completing treatment (TTB) and compared them to BCG-vaccinated healthy controls (HC). Levels of chemokines were measured by cytometric bead array. Levels of CXCL8, CXCL9 and CXCL10 were higher in ATB patients compared to HC, but they decreased in TTB. Levels of CCL2 and CCL5 in ATB patients were similar to those observed in HC. Thus, the high levels of CXC-chemokines detected during ATB, which can modulate the trafficking of immune cells from the periphery to the site of infection, were reversed by anti-mycobacterial treatment.

Anti-mycobacterial treatment reduces high plasma levels of CXC-chemokines detected in active tuberculosis by cytometric bead array

Chemokines recruit and activate leukocytes, assisting granuloma formation. Herein, we evaluated plasma chemokines in patients with active tuberculosis (ATB) and after completing treatment (TTB) and compared them to BCG-vaccinated healthy controls (HC). Levels of chemokines were measured by cytometric bead array. Levels of CXCL8, CXCL9 and CXCL10 were higher in ATB patients compared to HC, but they decreased in TTB. Levels of CCL2 and CCL5 in ATB patients were similar to those observed in HC. Thus, the high levels of CXC-chemokines detected during ATB, which can modulate the trafficking of immune cells from the periphery to the site of infection, were reversed by anti-mycobacterial treatment.