Human T-cell leukaemia virus type-1 (HTLV-1) and bovine leukaemia virus (BLV) infect T- and B-lymphocytes, respectively, provoking a polyclonal expansion that will evolve into an aggressive ...monoclonal leukaemia in ∼5% of individuals following a protracted latency period. It is generally assumed that early oncogenic changes are largely dependent on virus-encoded products, especially TAX and HBZ, while progression to acute leukaemia/lymphoma involves somatic mutations, yet that both are independent of proviral integration site that has been found to be very variable between tumours. Here, we show that HTLV-1/BLV proviruses are integrated near cancer drivers which they affect either by provirus-dependent transcription termination or as a result of viral antisense RNA-dependent cis-perturbation. The same pattern is observed at polyclonal non-malignant stages, indicating that provirus-dependent host gene perturbation contributes to the initial selection of the multiple clones characterizing the asymptomatic stage, requiring additional alterations in the clone that will evolve into full-blown leukaemia/lymphoma.
Treg are the main mediators of dominant tolerance. Their mechanisms of action and applications are subjects of considerable debate currently. However, a human microRNA (miR) Treg signature has not ...been described yet. We investigated human natural Treg and identified a signature composed of five miR (21, 31, 125a, 181c and 374). Among those, two were considerably under-expressed (miR-31 and miR-125a). We identified a functional target sequence for miR-31 in the 3' untranslated region (3' UTR) of FOXP3 mRNA. Using lentiviral transduction of fresh cord blood T cells, we demonstrated that miR-31 and miR-21 had an effect on FOXP3 expression levels. We showed that miR-31 negatively regulates FOXP3 expression by binding directly to its potential target site in the 3' UTR of FOXP3 mRNA. We next demonstrated that miR-21 acted as a positive, though indirect, regulator of FOXP3 expression. Transduction of the remaining three miR had no direct effect on FOXP3 expression or on the phenotype and will remain the subject of future investigations. In conclusion, not only have we identified and validated a miR signature for human natural Treg, but also unveiled some of the mechanisms by which this signature was related to the control of FOXP3 expression in these cells.
Early detection and treatment are critical for improving the outcome of patients with cancer
. Understanding the largely uncharted biology of carcinogenesis requires deciphering molecular processes ...in premalignant lesions, and revealing the determinants of the intralesional immune reaction during cancer development. The adaptive immune response within tumours has previously been shown to be strongest at the earliest stage of carcinoma
. Here we show that immune activation and immune escape occur before tumour invasion, and reveal the relevant immune biomarkers of the pre-invasive stages of carcinogenesis in the lung. We used gene-expression profiling and multispectral imaging to analyse a dataset of 9 morphological stages of the development of lung squamous cell carcinoma, which includes 122 well-annotated biopsies from 77 patients. We identified evolutionary trajectories of cancer and immune pathways that comprise (1) a linear increase in proliferation and DNA repair from normal to cancerous tissue; (2) a transitory increase of metabolism and early immune sensing, through the activation of resident immune cells, in low-grade pre-invasive lesions; (3) the activation of immune responses and immune escape through immune checkpoints and suppressive interleukins from high-grade pre-invasive lesions; and, ultimately, (4) the activation of the epithelial-mesenchymal transition in the invasive stage of cancer. We propose that carcinogenesis in the lung involves a dynamic co-evolution of pre-invasive bronchial cells and the immune response. These findings highlight the need to develop immune biomarkers for early detection as well as immunotherapy-based chemopreventive approaches for individuals who are at high risk of developing lung cancer.
Mesenchymal stromal cells (MSCs) are multipotent adult cells with relevant biological properties making them interesting tools for cell-based therapy. These cells have the ability to home to sites of ...injury and secrete bioactive factors as part of their therapeutic functions. However, depending on the local environment, diverse functions of MSCs can be modulated and thus can influence their therapeutic value. The specific cytokine milieu within the site of inflammation is vital in determining the fate and cell behaviors of MSCs. Indeed, inflammatory signals (called as inflammatory priming), may induce critical changes on the phenotype, multilineage potential, hematopoietic support and immunomodulatory capacity of MSCs. Thus, for appropriate clinical application of MSCs, it is important to well know and understand these effects. In summary, investigating MSC interactions with the inflammatory environment is necessary to empower the therapeutic value of MSCs.
The integration of a viral genome into the host genome has a major impact on the trajectory of the infected cell. Integration location and variation within the associated viral genome can influence ...both clonal expansion and persistence of infected cells. Methods based on short-read sequencing can identify viral insertion sites, but the sequence of the viral genomes within remains unobserved. We develop PCIP-seq, a method that leverages long reads to identify insertion sites and sequence their associated viral genome. We apply the technique to exogenous retroviruses HTLV-1, BLV, and HIV-1, endogenous retroviruses, and human papillomavirus.
Present chemotherapeutic regimens are marginally efficient in tumor cells being particularly resistant to radiotherapy and/or chemotherapy. We hypothesized that unresponsiveness of tumors to ...conventional therapeutic agents might be due to inappropriate gene expression resulting from epigenetic modifications and leading to transcriptional silencing. The goal of this study was to evaluate the anticancer effect of a histone deacetylase inhibitor, valproate, on mesothelioma cells in combination with pemetrexed and cisplatin, the usual first-line regimen of chemotherapy for this tumor.
We show that valproate augments apoptosis induced by pemetrexed and cisplatin in mesothelioma cell lines and in tumor cells from patient's biopsies. Onset of apoptosis involves both extrinsic and intrinsic pathways requiring enzymatic activities of caspases 8 and 9, respectively. Valproate but not suberoylanilide hydroxamic acid efficiently stimulates the production of reactive oxygen species. The free radical scavenger N-acetylcysteine inhibits apoptosis, indicating that reactive oxygen species are major mediators of valproate activity. As expected, valproate alone or combined with pemetrexed and cisplatin triggers hyperacetylation of histone H3. Bid protein processing in truncated t-Bid and cytochrome c release from mitochondria are significantly increased in the presence of valproate, providing a mechanistic rationale for improvement of the proapoptotic efficacy of cisplatin and pemetrexed. Finally, valproate when combined with pemetrexed and cisplatin prevents tumor growth in mouse models of epithelioid mesothelioma.
These observations support the potential additional efficacy of valproate in combination with pemetrexed and cisplatin for treatment of malignant mesothelioma.
Viral tumor models have significantly contributed to our understanding of oncogenic mechanisms. How transforming delta-retroviruses induce malignancy, however, remains poorly understood, especially ...as viral mRNA/protein are tightly silenced in tumors. Here, using deep sequencing of broad windows of small RNA sizes in the bovine leukemia virus ovine model of leukemia/lymphoma, we provide in vivo evidence of the production of noncanonical RNA polymerase III (Pol III)-transcribed viral microRNAs in leukemic B cells in the complete absence of Pol II 5′-LTR–driven transcriptional activity. Processed from a cluster of five independent self-sufficient transcriptional units located in a proviral region dispensable for in vivo infectivity, bovine leukemia virus microRNAs represent ∼40% of all microRNAs in both experimental and natural malignancy. They are subject to strong purifying selection and associate with Argonautes, consistent with a critical function in silencing of important cellular and/or viral targets. Bovine leukemia virus microRNAs are strongly expressed in preleukemic and malignant cells in which structural and regulatory gene expression is repressed, suggesting a key role in tumor onset and progression. Understanding how Pol III-dependent microRNAs subvert cellular and viral pathways will contribute to deciphering the intricate perturbations that underlie malignant transformation.
MicroRNAs (miRNAs) are small (19-22-nt) single-stranded noncoding RNA molecules whose deregulation of expression can contribute to human disease including the multistep processes of carcinogenesis in ...human. Circulating miRNAs are emerging biomarkers in many diseases and cancers such as type 2 diabetes, pulmonary disease, colorectal cancer, and gastric cancer among others; however, defining a plasma miRNA signature in acute myeloblastic leukemia (AML) that could serve as a biomarker for diagnosis or in the follow-up has not been done yet.
TaqMan miRNA microarray was performed to identify deregulated miRNAs in the plasma of AML patients. Quantitative real-time RT-PCR was used to validate the results. Receiver-operator characteristic (ROC) curve analysis was conducted to evaluate the diagnostic accuracy of the highly and significantly identified deregulated miRNA(s) as potential candidate biomarker(s).
The plasma expression level of let-7d, miR-150, miR-339, and miR-342 was down-regulated whilst that of let-7b, and miR-523 was up-regulated in the AML group at diagnosis compared to healthy controls. ROC curve analyses revealed an AUC (the areas under the ROC curve) of 0.835 (95% CI: 0.7119- 0.9581; P<0.0001) and 0.8125 (95% CI: 0.6796-0.9454; P=0.0005) for miR-150, and miR-342 respectively. Combined ROC analyses using these 2 miRNAs revealed an elevated AUC of 0.86 (95% CI: 0.7819-0.94; P<0.0001) indicating the additive effect in the diagnostic value of these 2 miRNAs. QRT-PCR results showed that the expression level of these two miRs in complete remission AML patients resembled that of healthy controls.
Our findings indicated that plasma miR-150 and miR-342 are novel important promising biomarkers in the diagnosis of AML. These novel and promising markers warrant validation in larger prospective studies.
In 1871, the observation of yellowish nodules in the enlarged spleen of a cow was considered to be the first reported case of bovine leukemia. The etiological agent of this lymphoproliferative ...disease, bovine leukemia virus (BLV), belongs to the deltaretrovirus genus which also includes the related human T-lymphotropic virus type 1 (HTLV-1). This review summarizes current knowledge of this viral system, which is important as a model for leukemogenesis. Recently, the BLV model has also cast light onto novel prospects for therapies of HTLV induced diseases, for which no satisfactory treatment exists so far.
Abstract
Bovine leukemia virus (BLV)-induced tumoral development is a multifactorial phenomenon that remains incompletely understood. Here, we highlight the critical role of the cellular ...CCCTC-binding factor (CTCF) both in the regulation of BLV transcriptional activities and in the deregulation of the three-dimensional (3D) chromatin architecture surrounding the BLV integration site. We demonstrated the in vivo recruitment of CTCF to three conserved CTCF binding motifs along the provirus. Next, we showed that CTCF localized to regions of transitions in the histone modifications profile along the BLV genome and that it is implicated in the repression of the 5′Long Terminal Repeat (LTR) promoter activity, thereby contributing to viral latency, while favoring the 3′LTR promoter activity. Finally, we demonstrated that BLV integration deregulated the host cellular 3D chromatin organization through the formation of viral/host chromatin loops. Altogether, our results highlight CTCF as a new critical effector of BLV transcriptional regulation and BLV-induced physiopathology.
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