HTLV-1 Tax-mediated inhibition of FOXO3a activity is critical for the persistence of terminally differentiated CD4+ T cells

Causal association of circulating immune cells and lymphoma: A Mendelian randomization study

Background

Malignant lymphoma (ML) is a group of malignant tumors originating from the lymphatic hematopoietic system. Previous studies have found a correlation between circulating immune cells and ML. Nonetheless, the precise influence of circulating immune cells on ML remains uncertain.

Methods

Based on publicly available genetic data, we explored causal associations between 731 immune cell signatures and ML risk. A total of four types of immune signatures, median fluorescence intensities, relative cell, absolute cell, and morphological parameters were included. Primary analysis was performed using inverse variance weighting (IVW) to assess the causal relationship between circulating immune cells and the risk of ML. Sensitivity analysis was conducted using Cochran's Q test, the Mendelian randomization Egger regression intercept test, and leave-one-out analysis.

Results

ML had a statistically significant effect on immunophenotypes. Twenty-three immunophenotypes were identified to be significantly associated with Hodgkin lymphoma risk through the IVW approach, and the odds ratio values of CD64 on CD14- CD16+ monocyte [2.31, 95% confidence interval (CI) = 1.41-3.79, P1 = 0.001], IgD+ CD24+ B-cell %lymphocyte (2.06, 95% CI = 1.13-3.79, P1 = 0.018), B-cell %lymphocyte (1.94, 95% CI = 1.08-3.50, P1 = 0.027), CD24+ CD27+ B-cell %lymphocyte (1.68, 95% CI = 1.03-2.74, P1 = 0.039), and CD14+ CD16- monocyte %monocyte (1.60, 95% CI = 1.15-2.24, P1 = 0.006) ranked in the top five. Eleven immunophenotypes were identified to be significantly associated with non-Hodgkin lymphoma risk, CD86 on granulocyte (2.35, 95% CI = 1.18-4.69, P1 = 0.015), CD28-CD8+ T-cell absolute count (1.76, 95% CI = 1.03-2.99, P1 = 0.036), CCR2 on myeloid dendritic cell (CD24+ CD27+ B cell, 95% CI = 1.02-1.66, P1 = 0.034), CD3 on effector memory CD8+ T cell (1.29, 95% CI = 1.02-1.64, P1 = 0.012), and natural killer T %lymphocyte (1.28, 95% CI = 1.01-1.62, P1 = 0.046) were ranked in the top five.

Conclusion

This study presents compelling evidence indicating the correlation between circulating immune cells and lymphoma, thus providing guidance for future clinical research.

Onco-Pathogen Mediated Cancer Progression and Associated Signaling Pathways in Cancer Development

Infection with viruses, bacteria, and parasites are thought to be the underlying cause of about 8-17% of the world's cancer burden, i.e., approximately one in every five malignancies globally is caused by an infectious pathogen. Oncogenesis is thought to be aided by eleven major pathogens. It is crucial to identify microorganisms that potentially act as human carcinogens and to understand how exposure to such pathogens occur as well as the following carcinogenic pathways they induce. Gaining knowledge in this field will give important suggestions for effective pathogen-driven cancer care, control, and, ultimately, prevention. This review will mainly focus on the major onco-pathogens and the types of cancer caused by them. It will also discuss the major pathways which, when altered, lead to the progression of these cancers.

Contribution of Epstein–Barr Virus Lytic Proteins to Cancer Hallmarks and Implications from Other Oncoviruses

Epstein–Barr virus (EBV) is a prevalent human gamma-herpesvirus that infects the majority of the adult population worldwide and is associated with several lymphoid and epithelial malignancies. EBV displays a biphasic life cycle, namely, latent and lytic replication cycles, expressing a diversity of viral proteins. Among the EBV proteins being expressed during both latent and lytic cycles, the oncogenic roles of EBV lytic proteins are largely uncharacterized. In this review, the established contributions of EBV lytic proteins in tumorigenesis are summarized according to the cancer hallmarks displayed. We further postulate the oncogenic properties of several EBV lytic proteins by comparing the evolutionary conserved oncogenic mechanisms in other herpesviruses and oncoviruses.

Progress on Ras/MAPK Signaling Research and Targeting in Blood and Solid Cancers

Simple Summary

The Ras-Raf-MEK-ERK signaling pathway is responsible for regulating cell proliferation, differentiation, and survival. Overexpression and overactivation of members within the signaling cascade have been observed in many solid and blood cancers. Research often focuses on targeting the pathway to disrupt cancer initiation and progression. We aimed to provide an overview of the pathway’s physiologic role and regulation, interactions with other pathways involved in cancer development, and mutations that lead to malignancy. Several blood and solid cancers are analyzed to illustrate the impact of the pathway’s dysregulation, stemming from mutation or viral induction. Finally, we summarized different approaches to targeting the pathway and the associated novel treatments being researched or having recently achieved approval.

Abstract

The mitogen-activated protein kinase (MAPK) pathway, consisting of the Ras-Raf-MEK-ERK signaling cascade, regulates genes that control cellular development, differentiation, proliferation, and apoptosis. Within the cascade, multiple isoforms of Ras and Raf each display differences in functionality, efficiency, and, critically, oncogenic potential. According to the NCI, over 30% of all human cancers are driven by Ras genes. This dysfunctional signaling is implicated in a wide variety of leukemias and solid tumors, both with and without viral etiology. Due to the strong evidence of Ras-Raf involvement in tumorigenesis, many have attempted to target the cascade to treat these malignancies. Decades of unsuccessful experimentation had deemed Ras undruggable, but recently, the approval of Sotorasib as the first ever KRas inhibitor represents a monumental breakthrough. This advancement is not without novel challenges. As a G12C mutant-specific drug, it also represents the issue of drug target specificity within Ras pathway; not only do many drugs only affect single mutational profiles, with few pan-inhibitor exceptions, tumor genetic heterogeneity may give rise to drug-resistant profiles. Furthermore, significant challenges in targeting downstream Raf, especially the BRaf isoform, lie in the paradoxical activation of wild-type BRaf by BRaf mutant inhibitors. This literature review will delineate the mechanisms of Ras signaling in the MAPK pathway and its possible oncogenic mutations, illustrate how specific mutations affect the pathogenesis of specific cancers, and compare available and in-development treatments targeting the Ras pathway.

Viral Infections: Negative Regulators of Apoptosis and Oncogenic Factors

The disruption of apoptotic cell death process is closely associated with the etiology of various diseases, including cancer. Permanent viral infections can cause different types of cancers. Oncogenic viruses manipulate both external and internal apoptosis pathways, and inhibit the activity of proapoptotic proteins and signaling pathways, which facilitates carcinogenesis. Ineffective immune surveillance or immune response suppression can induce uncontrolled virus propagation and host cell proliferation. In this review, we discuss current data that provide insights into mechanisms of apoptotic death suppression by viruses and their role in oncogenesis.

USP18 is a significant driver of memory CD4 T-cell reduced viability caused by type I IFN signaling during primary HIV-1 infection

The loss of Memory CD4 T-cells (Mem) is a major hallmark of HIV-1 immuno-pathogenesis and occurs early during the first months of primary infection. A lot of effort has been put into understanding the molecular mechanisms behind this loss, yet they still have not been fully identified. In this study, we unveil the unreported role of USP18 in the deleterious effects of sustained type I IFN signaling on Mem, including HIV-1-specific CD4 T-cells. We find that interfering with IFN-I signaling pathway in infected patients, notably by targeting the interferon-stimulated gene USP18, resulted in reduced PTEN expression similar to those observed in uninfected control donors. We show that AKT activation in response to cytokine treatment, T-cell receptor (TcR) triggering, as well as HIV-1 Gag stimulation was significantly improved in infected patients when PTEN or USP18 were inhibited. Finally, our data demonstrate that higher USP18 in Mem from infected patients prevent proper cell survival and long-lasting maintenance in an AKT-dependent manner. Altogether, we establish a direct role for type I IFN/USP18 signaling in the maintenance of total and virus-specific Mem and provide a new mechanism for the reduced survival of these populations during primary HIV-1 infection.

In this study, we expend our knowledge of how type I interferons (IFN-I) leads to memory CD4 T-cell defective survival by unveiling the molecular mechanism behind such impairments, placing USP18 at its center. Our data further deciphers the specific USP18-related mechanism that is responsible for such impairments by implicating AKT inhibition in a PTEN-dependent manner. Our findings also point to a potential use of neutralizing anti-interferon α/β receptor antibodies to rescue the defective memory CD4 T-cell survival during HIV-1 infection, even in HIV-1 specific CD4 T-cell. To conclude, our findings provide the characterization of the molecular pathway leading to disturbances caused by sustained IFN-I signaling which occurs early during primary HIV-1 infection, complementing current knowledge which placed sustained IFN-I signaling as detrimental to the host during this infection.

Molecular mechanisms of viral oncogenesis in humans

Viral infection is a major contributor to the global cancer burden. Recent advances have revealed that seven known oncogenic viruses promote tumorigenesis through shared host cell targets and pathways. A comprehensive understanding of the principles of viral oncogenesis may enable the identification of unknown infectious aetiologies of cancer and the development of therapeutic or preventive strategies for virus-associated cancers. In this Review, we discuss the molecular mechanisms of viral oncogenesis in humans. We highlight recent advances in understanding how viral manipulation of host cellular signalling, DNA damage responses, immunity and microRNA targets promotes the initiation and development of cancer.

The roles of FOX proteins in virus-associated cancers

Forkhead box (FOX) proteins play a crucial role in regulating the expression of genes involved in multiple biological processes, such as metabolism, development, differentiation, proliferation, apoptosis, migration, invasion, and longevity. Deregulation of FOX proteins is commonly associated with cancer initiation, progression, and chemotherapeutic drug resistance in many human tumors. FOX proteins deregulate through genetic events and the perturbation of posttranslational modification. The purpose of the present review is to describe the deregulation of FOX proteins by oncoviruses. Oncoviruses utilize various mechanisms to deregulate FOX proteins, including alterations in posttranslational modifications, cellular localization independently of posttranslational modifications, virus-encoded miRNAs, activation or suppression of a series of cell signaling pathways. This deregulation can affect proliferation, metastasis, chemotherapy resistance, and immunosuppression in virus-induced cancers and help to chronic viral infection, development of gluconeogenic responses, and inflammation. Since the PI3K/Akt/mTOR signaling pathway is the upstream FOXO, suppressing it can cause FOXO function to return, and this can be one of the reasons for patients to recover from the infection of the viruses used to treat these inhibitors. Hence, FOX proteins could serve as prognosis markers and target therapy specifically in cancers caused by oncoviruses.

Hepatitis C virus regulates proprotein convertase subtilisin/kexin type 9 promoter activity

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secretory serine protease mainly expressed in liver. Although PCSK9 has been shown to inhibit hepatitis C virus (HCV) entry and replication, whether HCV regulates PCSK9 transcription has not been well studied. PCSK9 promoter activity is modulated by numerous transcription factors including sterol-regulatory element binding protein (SREBP)-1a, -1c, -2, hepatocyte nuclear factor-1 (HNF-1), and forkhead box O3 (FoxO3). Since they are differently regulated by HCV, we studied the effects of these transcription factors on PCSK9 promoter activity in the context of HCV infection and replication. We demonstrated that PCSK9 promoter activity was up-regulated after HCV infection and in HCV genomic replicon cells. We also studied the effects of HCV proteins on the PCSK9 promoter activity. While HCV structural proteins core, E1, and E2 had no effect, NS2, NS3, NS3-4A, NS5A and NS5B enhanced, and p7 and NS4B decreased PCSK9 promoter activity. Furthermore, we showed that transcription factors SREBP-1c, HNF-1α and specificity protein 1 increased PCSK9 promoter activity in HCV replicon cells, whereas SREBP-1a, HNF-1β and FoxO3 had an inhibitory effect. These results demonstrated the molecular mechanisms of how HCV modulates PCSK9 promoter activity and advanced our understanding on the mutual interactions between HCV and PCSK9.

Evaluation of Innate Immune Gene Expression Following HDAC Inhibitor Treatment by High Throughput qPCR and PhosFlow Cytometry

The dynamics of chromatin structure contribute to the regulation of gene transcription and in part, the changes in chromatin structure associated with gene activation/repression are a function of the state of histone acetylation. Histone deacetylases (HDACs) deacetylate histone tails leading to a more compact structure of chromatin that in turn represses gene transcription. Given the rapid activation and/or repression of gene networks following microbial infection, the role of HDACs in the epigenetic regulation of genes involved in the innate and adaptive immune responses has become an area of extensive research. In relation to the immune-modulatory properties of HDAC inhibitors, we provide in the following methodological article an extended description of two techniques-a high throughput qPCR assay combined with PhosFlow cytometry-to evaluate the modulation of antiviral and inflammatory signaling cascades following HDAC inhibitor treatment. The high-throughput qPCR assay is based on the nanofluidic Fluidigm BioMark system that permits the analysis of up to 9216 qPCR reactions at once in a self-design open array chip. Together with the more refined analysis provided with the Phosflow technique, these two strategies offer invaluable tools to measure modulation of innate immune gene networks.

Multifaceted functions and roles of HBZ in HTLV-1 pathogenesis

Human T cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus responsible for the development of adult T-cell leukemia (ATL). Although HTLV-1 harbors an oncogene, tax, that transforms T cells in vitro and induces leukemia in transgenic mice, tax expression is frequently disrupted in ATL, making the oncogenesis of ATL a bit mysterious. The HTLV-1 bZIP factor (HBZ) gene was discovered in 2002 and has been found to promote T-cell proliferation and cause lymphoma in transgenic mice. Thus HBZ has become a novel hotspot of HTLV-1 research. This review summarizes the current findings on HBZ with a special focus on its potential links to the oncogenesis of ATL. We propose viewing HBZ as a critical contributing factor in ATL development.