Selective targeting of JAK/STAT signaling is potentiated by Bcl-xL blockade in IL-2-dependent adult T-cell leukemia

Enhancement of vincristine sensitivity in retinoblastoma through Janus kinase inhibition by ruxolitinib

Chemotherapy remains the main approach conserving vision during the treatment of retinoblastoma, the most prevalent eye cancer in children. Unfortunately, the development of chemoresistance stands as the primary reason for treatment failure. Within this study, we showed that prolonged exposure to vincristine led to heightened expression of JAK1 and JAK2 in retinoblastoma cells, while the other members of the JAK family exhibited no such changes. Employing a genetic intervention, we demonstrated the efficacy of depleting either JAK1 or JAK2 in countering vincristine-resistant retinoblastoma cells. In addition, the dual depletion of both JAK1 and JAK2 produced a more potent inhibitory outcome compared to the depletion of either gene alone. We further demonstrated that ruxolitinib, a small molecular inhibitor of JAK1/2, effectively reduced viability and colony formation in vincristine-resistant retinoblastoma cells. It also acts synergistically with vincristine in retinoblastoma cells regardless of inherent cellular and genetic heterogeneity. The effectiveness of ruxolitinib as standalone treatment against chemoresistant retinoblastoma, as well as its combination with vincristine, was validated in multiple retinoblastoma mouse models. Importantly, mice exhibited favorable tolerance to ruxolitinib administration. We confirmed that the underlying mechanism of ruxolitinib's action in chemoresistant retinoblastoma cells is the inhibition of Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling. Our study reveals that the underlying mechanism driving ruxolitinib's impact on chemoresistant retinoblastoma cells is the inhibition of JAK/STAT signaling. This study reveals the contribution of JAK1/2 to the development of chemoresistance in retinoblastoma and underscores the effectiveness of targeting JAK1/2 as a strategy to sensitize retinoblastoma to chemotherapy.

JAK/STAT in leukemia: a clinical update

Over the past three decades, considerable efforts have been expended on understanding the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway in leukemia, following the identification of the JAK2V617F mutation in myeloproliferative neoplasms (MPNs). The aim of this review is to summarize the latest progress in our understanding of the involvement of the JAK/STAT signaling pathway in the development of leukemia. We also attempt to provide insights into the current use of JAK/STAT inhibitors in leukemia therapy and explore pertinent clinical trials in this field.

HTLV-1 Tax Tug-of-War: Cellular Senescence and Death or Cellular Transformation

Human T cell leukemia virus type 1 (HTLV-1) is a retrovirus associated with a lymphoproliferative disease known as adult T cell leukemia/lymphoma (ATLL). HTLV-1 infection efficiently transforms human T cells in vivo and in vitro. The virus does not transduce a proto-oncogene, nor does it integrate into tumor-promoting genomic sites. Instead, HTLV-1 uses a random mutagenesis model, resulting in cellular transformation. Expression of the viral protein Tax is critical for the immortalization of infected cells by targeting specific cellular signaling pathways. However, Tax is highly immunogenic and represents the main target for the elimination of virally infected cells by host cytotoxic T cells (CTLs). In addition, Tax expression in naïve cells induces pro-apoptotic signals and has been associated with the induction of non-replicative cellular senescence. This review will explore these conundrums and discuss the mechanisms used by the Tax viral oncoprotein to influence life-and-death cellular decisions and affect HTLV-1 pathogenesis.

Human T-Cell Leukemia Virus Type 1 Oncogenesis between Active Expression and Latency: A Possible Source for the Development of Therapeutic Targets

The human T-cell leukemia virus type 1 (HTLV-1) is the only known human oncogenic retrovirus. HTLV-1 can cause a type of cancer called adult T-cell leukemia/lymphoma (ATL). The virus is transmitted through the body fluids of infected individuals, primarily breast milk, blood, and semen. At least 5-10 million people in the world are infected with HTLV-1. In addition to ATL, HTLV-1 infection can also cause HTLV-I-associated myelopathy (HAM/TSP). ATL is characterized by a low viral expression and poor prognosis. The oncogenic mechanism triggered by HTLV-1 is extremely complex and the molecular pathways are not fully understood. However, viral regulatory proteins Tax and HTLV-1 bZIP factor (HBZ) have been shown to play key roles in the transformation of HTLV-1-infected T cells. Moreover, several studies have shown that the final fate of HTLV-1-infected transformed Tcell clones is the result of a complex interplay of HTLV-1 oncogenic protein expression with cellular transcription factors that subvert the cell cycle and disrupt regulated cell death, thereby exerting their transforming effects. This review provides updated information on the mechanisms underlying the transforming action of HTLV-1 and highlights potential therapeutic targets to combat ATL.

Targeting Bcl-xL is a potential therapeutic strategy for extranodal NK/T cell lymphoma

Extranodal natural killer/T cell lymphoma, nasal type (ENKTL) is an aggressive lymphoid malignancy with a poor prognosis and lacks standard treatment. Targeted therapies are urgently needed. Here we systematically investigated the druggable mechanisms through chemogenomic screening and identified that Bcl-xL-specific BH3 mimetics effectively induced ENKTL cell apoptosis. Notably, the specific accumulation of Bcl-xL, but not other Bcl-2 family members, was verified in ENKTL cell lines and patient tissues. Furthermore, Bcl-xL high expression was shown to be closely associated with worse patient survival. The critical role of Bcl-xL in ENKTL cell survival was demonstrated utilizing selective inhibitors, genetic silencing, and a specific degrader. Additionally, the IL2-JAK1/3-STAT5 signaling was implicated in Bcl-xL dysregulation. In vivo, Bcl-xL inhibition reduced tumor burden, increased apoptosis, and prolonged survival in ENKTL cell line xenograft and patient-derived xenograft models. Our study indicates Bcl-xL as a promising therapeutic target for ENKTL, warranting monitoring in ongoing clinical trials by targeting Bcl-xL.

The Therapeutic Values of IL-7/IL-7R and the Recombinant Derivatives in Glioma: A Narrative Review

Interleukin-7 (IL-7) is essential for maintaining the immune system's defense functions by regulating the development and homeostasis of lymphocytes. Findings have shown the high efficacy of IL-7/IL-7 receptor (IL-7R)-based immunotherapy on various malignancies, with confirmation in both animal models and humans. In recent years, the progression-free survival and overall survival of patients suffering from gliomas significantly increased by introducing C7R-expressing chimeric antigen receptor (CAR)-T cells and long-acting IL-7 agonists such as NT-I7 (rhIL-7-hyFc, Efineptakin alfa). However, the effect of IL-7-based immunotherapies on the resistance of tumor cells to chemotherapy (when used simultaneously with chemotherapy agents) is still ambiguous and requires further studies. This article first reviews the pathophysiological roles of IL-7/IL-7R in tumors, focusing on gliomas. Subsequently, it discusses the therapeutic values of IL-7/IL-7R and the recombinant derivatives in gliomas.

Therapeutic efficacy of the resorcylic acid lactone LL-Z1640-2 for adult T-cell leukaemia/lymphoma

Adult T-cell leukaemia/lymphoma (ATL) remains incurable. The NF-κB and interferon regulatory factor 4 (IRF4) signalling pathways are among the critical survival pathways for the progression of ATL. TGF-β-activated kinase 1 (TAK1), an IκB kinase-activating kinase, triggers the activation of NF-κB. The resorcylic acid lactone LL-Z1640-2 is a potent irreversible inhibitor of TAK1/extracellular signal-regulated kinase 2 (ERK2). We herein examined the therapeutic efficacy of LL-Z1640-2 against ATL. LL-Z1640-2 effectively suppressed the in vivo growth of ATL cells. It induced in vitro apoptosis and inhibited the nuclear translocation of p65/RelA in ATL cells. The knockdown of IRF4 strongly induced ATL cell death while downregulating MYC. LL-Z1640-2 as well as the NF-κB inhibitor BAY11-7082 decreased the expression of IRF4 and MYC at the protein and mRNA levels, indicating the suppression of the NF-κB-IRF4-MYC axis. The treatment with LL-Z1640-2 also mitigated the phosphorylation of p38 MAPK along with the expression of CC chemokine receptor 4. Furthermore, the inhibition of STAT3/5 potentiated the cytotoxic activity of LL-Z1640-2 against IL-2-responsive ATL cells in the presence of IL-2. Therefore, LL-Z1640-2 appears to be an effective treatment for ATL. Further studies are needed to develop more potent compounds that retain the active motifs of LL-Z1640-2.

Reigniting hope in cancer treatment: the promise and pitfalls of IL-2 and IL-2R targeting strategies

Interleukin-2 (IL-2) and its receptor (IL-2R) are essential in orchestrating immune responses. Their function and expression in the tumor microenvironment make them attractive targets for immunotherapy, leading to the development of IL-2/IL-2R-targeted therapeutic strategies. However, the dynamic interplay between IL-2/IL-2R and various immune cells and their dual roles in promoting immune activation and tolerance presents a complex landscape for clinical exploitation. This review discusses the pivotal roles of IL-2 and IL-2R in tumorigenesis, shedding light on their potential as diagnostic and prognostic markers and their therapeutic manipulation in cancer. It underlines the necessity to balance the anti-tumor activity with regulatory T-cell expansion and evaluates strategies such as dose optimization and selective targeting for enhanced therapeutic effectiveness. The article explores recent advancements in the field, including developing genetically engineered IL-2 variants, combining IL-2/IL-2R-targeted therapies with other cancer treatments, and the potential benefits of a multidimensional approach integrating molecular profiling, immunological analyses, and clinical data. The review concludes that a deeper understanding of IL-2/IL-2R interactions within the tumor microenvironment is crucial for realizing the full potential of IL-2-based therapies, heralding the promise of improved outcomes for cancer patients.

Mouse Models for HTLV-1 Infection and Adult T Cell Leukemia

Adult T cell leukemia (ATL) is an aggressive hematologic disease caused by human T cell leukemia virus type 1 (HTLV-1) infection. Various animal models of HTLV-1 infection/ATL have been established to elucidate the pathogenesis of ATL and develop appropriate treatments. For analyses employing murine models, transgenic and immunodeficient mice are used because of the low infectivity of HTLV-1 in mice. Each mouse model has different characteristics that must be considered before use for different HTLV-1 research purposes. HTLV-1 Tax and HBZ transgenic mice spontaneously develop tumors, and the roles of both Tax and HBZ in cell transformation and tumor growth have been established. Severely immunodeficient mice were able to be engrafted with ATL cell lines and have been used in preclinical studies of candidate molecules for the treatment of ATL. HTLV-1-infected humanized mice with an established human immune system are a suitable model to characterize cells in the early stages of HTLV-1 infection. This review outlines the characteristics of mouse models of HTLV-1 infection/ATL and describes progress made in elucidating the pathogenesis of ATL and developing related therapies using these mice.

Integrated molecular and immunological features of human T-lymphotropic virus type 1 infection and disease progression to adult T-cell leukaemia or lymphoma

The human T-lymphotropic virus type 1 (HTLV-1) retrovirus infects 10-20 million people globally, with endemic regions in southwestern Japan, the Caribbean basin, Africa, and central Australia. HTLV-1 is associated with lifelong infection and immune suppression, resulting in a range of serious sequalae, including adult T-cell leukaemia or lymphoma (ATLL) in 5% of cases. To date, there are no preventive or curative treatments for HTLV-1 and treatment outcomes for ATLL remain generally poor. Depending on the disease subtype, overall survival is 8-55 months. Recent advancements in the past decade have identified genetic, molecular, and immunological events occurring throughout the lives of individuals infected with HTLV-1 and of those who progress to ATLL. In addition, updated guidelines for clinical management have been published. With the aim of focusing research efforts on the development of treatments for both HTLV-1 infections and ATLL, we have conceptualised a four-step disease model for HTLV-1-associated ATLL: (1) viral exposure, (2) establishment of chronic infection, (3) cellular transformation and evolution, and (4) disease presentation and management. For each stage we describe the clinical features, molecular and immunological factors involved, potential biomarkers of disease progression, and the therapeutic applicability of individual targets. We also discuss emerging concepts and novel treatment approaches. Our hope is that this model will promote research interest and guide the testing of new treatments for this neglected virus and its associated rare cancer.

Possible Mechanisms of Oxidative Stress-Induced Skin Cellular Senescence, Inflammation, and Cancer and the Therapeutic Potential of Plant Polyphenols

As the greatest defense organ of the body, the skin is exposed to endogenous and external stressors that produce reactive oxygen species (ROS). When the antioxidant system of the body fails to eliminate ROS, oxidative stress is initiated, which results in skin cellular senescence, inflammation, and cancer. Two main possible mechanisms underlie oxidative stress-induced skin cellular senescence, inflammation, and cancer. One mechanism is that ROS directly degrade biological macromolecules, including proteins, DNA, and lipids, that are essential for cell metabolism, survival, and genetics. Another one is that ROS mediate signaling pathways, such as MAPK, JAK/STAT, PI3K/AKT/mTOR, NF-κB, Nrf2, and SIRT1/FOXO, affecting cytokine release and enzyme expression. As natural antioxidants, plant polyphenols are safe and exhibit a therapeutic potential. We here discuss in detail the therapeutic potential of selected polyphenolic compounds and outline relevant molecular targets. Polyphenols selected here for study according to their structural classification include curcumin, catechins, resveratrol, quercetin, ellagic acid, and procyanidins. Finally, the latest delivery of plant polyphenols to the skin (taking curcumin as an example) and the current status of clinical research are summarized, providing a theoretical foundation for future clinical research and the generation of new pharmaceuticals and cosmetics.

The Role of IL-7 and IL-7R in Cancer Pathophysiology and Immunotherapy

Interleukin-7 (IL-7) is a multipotent cytokine that maintains the homeostasis of the immune system. IL-7 plays a vital role in T-cell development, proliferation, and differentiation, as well as in B cell maturation through the activation of the IL-7 receptor (IL-7R). IL-7 is closely associated with tumor development and has been used in cancer clinical research and therapy. In this review, we first summarize the roles of IL-7 and IL-7Rα and their downstream signaling pathways in immunity and cancer. Furthermore, we summarize and discuss the recent advances in the use of IL-7 and IL-7Rα as cancer immunotherapy tools and highlight their potential for therapeutic applications. This review will help in the development of cancer immunotherapy regimens based on IL-7 and IL-7Rα, and will also advance their exploitation as more effective and safe immunotherapy tools.

Novel Therapies in Myelofibrosis: Beyond JAK Inhibitors

PURPOSE OF REVIEW

To discuss the current treatment paradigm, review novel targets, and summarize completed and ongoing clinical trials that may lead to a paradigm shifts in the management of myelofibrosis (MF).

RECENT FINDINGS

In addition to the recent approval and ongoing late-stage development of multiple novel JAK inhibitors, recent clinical studies demonstrate therapeutic potential of targeting multiple alternate proteins and pathways including BET, MDM2, telomerase, BCL2, LSD1, PI3K, SMAC, and PTX2 in patients with MF. MF is a myeloproliferative neoplasm characterized by clonal proliferation of myeloid cells and bone marrow fibrosis often causing cytopenias, extramedullary hematopoiesis resulting in hepatosplenomegaly, and increased pro-inflammatory cytokine production driving systemic symptoms. A significant proportion of morbidity and mortality is related to the propensity to transform to acute leukemia. Allogeneic hematopoietic stem cell transplantation is the only curative therapy; however, due to the high associated mortality, this treatment is not an option for the majority of patients with MF. Currently, there are three targeted Food and Drug Administration (FDA)-approved therapies for MF which include ruxolitinib, fedratinib, and pacritinib, all part of the JAK inhibitor class. Many patients are unable to tolerate, do not respond, or develop resistance to existing therapies, leaving a large unmet medical need. In this review, we discuss the current treatment paradigm and novel therapies in development for the treatment of MF. We review the scientific rationale of each targeted pathway. We summarize updated clinical data and ongoing trials that may lead to FDA approval of these agents.

CXCL13 expressed on inflamed cerebral blood vessels recruit IL-21 producing TFH cells to damage neurons following stroke

BACKGROUND

Ischemic stroke is a leading cause of mortality worldwide, largely due to the inflammatory response to brain ischemia during post-stroke reperfusion. Despite ongoing intensive research, there have not been any clinically approved drugs targeting the inflammatory component to stroke. Preclinical studies have identified T cells as pro-inflammatory mediators of ischemic brain damage, yet mechanisms that regulate the infiltration and phenotype of these cells are lacking. Further understanding of how T cells migrate to the ischemic brain and facilitate neuronal death during brain ischemia can reveal novel targets for post-stroke intervention.

METHODS

To identify the population of T cells that produce IL-21 and contribute to stroke, we performed transient middle cerebral artery occlusion (tMCAO) in mice and performed flow cytometry on brain tissue. We also utilized immunohistochemistry in both mouse and human brain sections to identify cell types and inflammatory mediators related to stroke-induced IL-21 signaling. To mechanistically demonstrate our findings, we employed pharmacological inhibitor anti-CXCL13 and performed histological analyses to evaluate its effects on brain infarct damage. Finally, to evaluate cellular mechanisms of stroke, we exposed mouse primary neurons to oxygen glucose deprivation (OGD) conditions with or without IL-21 and measured cell viability, caspase activity and JAK/STAT signaling.

RESULTS

Flow cytometry on brains from mice following tMCAO identified a novel population of cells IL-21 producing CXCR5+ CD4+ ICOS-1+ T follicular helper cells (TFH) in the ischemic brain early after injury. We observed augmented expression of CXCL13 on inflamed brain vascular cells and demonstrated that inhibition of CXCL13 protects mice from tMCAO by restricting the migration and influence of IL-21 producing TFH cells in the ischemic brain. We also illustrate that neurons express IL-21R in the peri-infarct regions of both mice and human stroke tissue in vivo. Lastly, we found that IL-21 acts on mouse primary ischemic neurons to activate the JAK/STAT pathway and induce caspase 3/7-mediated apoptosis in vitro.

CONCLUSION

These findings identify a novel mechanism for how pro-inflammatory T cells are recruited to the ischemic brain to propagate stroke damage and provide a potential new therapeutic target for stroke.

Long Noncoding RNA: Shining Stars in the Immune Microenvironment of Gastric Cancer

Gastric cancer (GC) is a kind of malignant tumor disease that poses a serious threat to human health. The GC immune microenvironment (TIME) is a very complex tumor microenvironment, mainly composed of infiltrating immune cells, extracellular matrix, tumor-associated fibroblasts, cytokines and chemokines, all of which play a key role in inhibiting or promoting tumor development and affecting tumor prognosis. Long non-coding RNA (lncRNA) is a non-coding RNA with a transcript length is more than 200 nucleotides. LncRNAs are expressed in various infiltrating immune cells in TIME and are involved in innate and adaptive immune regulation, which is closely related to immune escape, migration and invasion of tumor cells. LncRNA-targeted therapeutic effect prediction for GC immunotherapy provides a new approach for clinical research on the disease.

Regulation of HTLV-1 Transformation

Human T-cell leukemia virus type 1 (HTLV-1) is the only identified oncogenic human retrovirus. HTLV-1 infects approximately 5–10 million people worldwide and is the infectious cause of adult T-cell leukemia/lymphoma (ATL) and several chronic inflammatory diseases, including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), dermatitis, and uveitis. Unlike other oncogenic retroviruses, HTLV-1 does not capture a cellular proto-oncogene or induce proviral insertional mutagenesis. HTLV-1 is a trans-activating retrovirus and encodes accessory proteins that induce cellular transformation over an extended period of time, upwards of several years to decades. Inarguably the most important viral accessory protein involved in transformation is Tax. Tax is a multifunctional protein that regulates several different pathways and cellular processes. This single viral protein is able to modulate viral gene expression, activate NF-κB signaling pathways, deregulate the cell cycle, disrupt apoptosis, and induce genomic instability. The summation of these processes results in cellular transformation and virus-mediated oncogenesis. Interestingly, HTLV-1 also encodes a protein called Hbz from the antisense strand of the proviral genome that counters many Tax functions in the infected cell, such as Tax-mediated viral transcription and NF-κB activation. However, Hbz also promotes cellular proliferation, inhibits apoptosis, and disrupts genomic integrity. In addition to viral proteins, there are other cellular factors such as MEF-2, superoxide-generating NAPDH oxidase 5-α (Nox5α), and PDLIM2 which have been shown to be critical for HTLV-1-mediated T-cell transformation. This review will highlight the important viral and cellular factors involved in HTLV-1 transformation and the available in vitro and in vivo tools used to study this complex process.

Inhibition of ATL cell proliferation by polymerized proanthocyanidin from blueberry leaves through JAK proteolysis

We have previously reported that the proanthocyanidin (PAC) fraction of blueberry leaf extract (BB-PAC) inhibits the proliferation of human T lymphotropic retrovirus (HTLV-1)-infected adult T-cell leukemia (ATL) by inducing apoptosis. In the present study, we further analyzed the structure of BB-PAC and elucidated the molecular mechanism underlying the inhibitory function of HTLV-1 infected and ATL cells. After hot water extraction with fractionation with methanol-acetone, BB-PAC was found to be concentrated in fractions 4 to 7 (Fr 7). The strongest inhibition of ATL cell growth was observed with Fr7, which contained the highest BB-PAC polymerization degree of 14. The basic structure of BB-PAC is mainly B-type bonds, with A-type bonds (7.1%) and cinchonain I units as the terminal unit (6.1%). The molecular mechanism of cytotoxicity observed around Fr7 against ATL cells was the degradation of JAK1 to 3 and the dephosphorylation of STAT3/5, which occurs by proteasome-dependent proteolysis, confirming that PAC directly binds to HSP90. JAK degradation was caused by proteasome-dependent proteolysis, and we identified the direct binding of PAC to HSP90. In addition, the binding of cochaperone ATPase homolog 1 (AHA1) to HSP90, which is required for activation of the cofactor HSP90, was inhibited by BB-PAC treatment. Therefore, BB-PAC inhibited the formation of the HSP90/AHA1 complex and promoted the degradation of JAK protein due to HSP90 dysfunction. These results suggest that the highly polymerized PAC component from blueberry leaves has great potential as a preventive and therapeutic agent against HTLV-1 infected and ATL cells.

Interleukin (IL)-9 Supports the Tumor-Promoting Environment of Chronic Lymphocytic Leukemia

Simple Summary

Interleukin 9 (IL-9), a soluble factor secreted by immune cells, has been found in several tumor niches where, depending on the specific tumor type, it either promotes or counteracts tumor development. Recently, IL-9 has been implicated in the development of chronic lymphocytic leukemia, although the underlying molecular mechanism remains unknown. Here, we summarize the current knowledge concerning the roles of IL-9 in disease, with a focus on its implication in the pathogenesis of chronic lymphocytic leukemia.

Abstract

Interleukin (IL)-9 is a soluble factor secreted by immune cells into the microenvironment. Originally identified as a mediator of allergic responses, IL-9 has been detected in recent years in several tumor niches. In solid tumors, it mainly promotes anti-tumor immune responses, while in hematologic malignancies, it sustains the growth and survival of neoplastic cells. IL-9 has been recently implicated in the pathogenesis of chronic lymphocytic leukemia; however, the molecular mechanisms underlying its contribution to this complex neoplasia are still unclear. Here, we summarize the current knowledge of IL-9 in the tumor microenvironment, with a focus on its role in the pathogenesis of chronic lymphocytic leukemia.

Intelligent photothermal dendritic cells restart the cancer immunity cycle through enhanced immunogenic cell death

Dendritic cells (DCs) play a pivotal role in initiating antigen-specific tumor immunity. However, the abnormal function of DCs owing to the immunosuppressive tumor microenvironment (TME) and the insufficient number of tumor infiltrating DCs could promote immune tolerance and tumor immune escape. Thus, there is great potential to employ DCs to induce efficient antitumor immunity. In this paper, we developed intelligent DCs (iDCs), which consist of nanoparticles loaded with photothermal agents (IR-797) and coated with a mature DC membrane. The DC cell membrane on the surface of iDCs preserves the ability to present antigens and prime T cells. The iDCs can also enter the lymph node and stimulate T cells. The activated T cells reduced the expression of heat shock proteins (HSPs) in tumor cells, rendering them more sensitive to heat stress. Subsequently, we used mild photothermal therapy (42-45 °C) to induce immunogenic cell death and contribute to a synergistic antitumor effect. iDCs as a refined and precise system in combination with DC-based immunotherapy and thermal therapy can be stored long-term and on a large scale, so they can be applied in many patients.

Janus Kinase Signaling: Oncogenic Criminal of Lymphoid Cancers

Simple Summary

Janus kinases (JAKs) are transmembrane receptors that pass signals from extracellular ligands to downstream. Increasing evidence has suggested that JAK family aberrations promote lymphoid cancer pathogenesis and progression through mediating gene expression via the JAK/STAT pathway or noncanonical JAK signaling. We are here to review how canonical JAK/STAT and noncanonical JAK signalings are represented and deregulated in lymphoid malignancies and how to target JAK for therapeutic purposes.

Abstract

The Janus kinase (JAK) family are known to respond to extracellular cytokine stimuli and to phosphorylate and activate signal transducers and activators of transcription (STAT), thereby modulating gene expression profiles. Recent studies have highlighted JAK abnormality in inducing over-activation of the JAK/STAT pathway, and that the cytoplasmic JAK tyrosine kinases may also have a nuclear role. A couple of anti-JAK therapeutics have been developed, which effectively harness lymphoid cancer cells. Here we discuss mutations and fusions leading to JAK deregulations, how upstream nodes drive JAK expression, how classical JAK/STAT pathways are represented in lymphoid malignancies and the noncanonical and nuclear role of JAKs. We also summarize JAK inhibition therapeutics applied alone or synergized with other drugs in treating lymphoid malignancies.

Oclacitinib, a Janus Kinase Inhibitor, Reduces the Frequency of IL-4- and IL-10-, but Not IFN-γ-, Producing Murine CD4+ and CD8+ T Cells and Counteracts the Induction of Type 1 Regulatory T Cells

The purpose of the present study was to broaden the knowledge and understanding of the effects of oclacitinib (OCL), a Janus kinase inhibitor, on T cells in the context of both the immune mechanisms underlying anti-inflammatory and anti-allergic properties of the drug and its safety. The results indicate that beneficial effects of OCL in the treatment of skin allergic diseases may be partially mediated by the inhibition of IL-4 production in CD4+ and CD8+ T cells. To a certain extent, the antiproliferative effect of OCL on CD8+ T cells may also contribute to its therapeutic effect. The study found that OCL does not affect the proliferation of CD4+ T cells or the number of IFN-γ- and IL-17-producing CD4+ and CD8+ T cells. Moreover, OCL was found to counteract the induction of type 1 regulatory T (Tr1) cells and to act as a strong inhibitor of IL-10 production in both CD4+ and CD8+ T cells. Thus, these results indicate that beneficial effects of OCL in the treatment of skin allergic diseases are not mediated through: (a) the abolishment of IFN-γ and IL-17-production in CD4+ and CD8+ T cells; (b) generation of Tr1 cells; (c) inhibition of CD4+ T cell proliferation; (d) induction of IL-10 production in CD4+ T cells. The results of this study strongly suggest that, with respect to the evaluated parameters, OCL exerts a suppressive effect on Th2- but not Th1-mediated immunity.

The Emerging Role of Suppressors of Cytokine Signaling (SOCS) in the Development and Progression of Leukemia

Cytokines are pleiotropic signaling molecules that execute an essential role in cell-to-cell communication through binding to cell surface receptors. Receptor binding activates intracellular signaling cascades in the target cell that bring about a wide range of cellular responses, including induction of cell proliferation, migration, differentiation, and apoptosis. The Janus kinase and transducers and activators of transcription (JAK/STAT) signaling pathways are activated upon cytokines and growth factors binding with their corresponding receptors. The SOCS family of proteins has emerged as a key regulator of cytokine signaling, and SOCS insufficiency leads to constitutive activation of JAK/STAT signaling and oncogenic transformation. Dysregulation of SOCS expression is linked to various solid tumors with invasive properties. However, the roles of SOCS in hematological malignancies, such as leukemia, are less clear. In this review, we discuss the recent advances pertaining to SOCS dysregulation in leukemia development and progression. We also highlight the roles of specific SOCS in immune cells within the tumor microenvironment and their possible involvement in anti-tumor immunity. Finally, we discuss the epigenetic, genetic, and post-transcriptional modifications of SOCS genes during tumorigenesis, with an emphasis on leukemia.

JAK Be Nimble: Reviewing the Development of JAK Inhibitors and JAK Inhibitor Combinations for Special Populations of Patients with Myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm hallmarked by uncontrolled blood counts, constitutional symptoms, extramedullary hematopoiesis, and an increased risk of developing acute myeloid leukemia. Janus kinase (JAK) inhibitors are the most common treatment for MF due to their ability to reduce spleen size and improve disease-related symptoms; however, JAK inhibitors are not suitable for every patient and their impact on MF is limited in several respects. Novel JAK inhibitors and JAK inhibitor combinations are emerging that aim to enhance the treatment landscape, providing deeper responses to a broader population of patients with the continued hope of providing disease modification and improving long-term outcomes. In this review, we highlight several specific areas of unmet need within MF. Subsequently, we review agents that target those areas of unmet need, focusing specifically on the JAK inhibitors, momelotinib, pacritinib, itacitinib, and NS-018 as well as JAK inhibitor combination approaches using CPI-0610, navitoclax, parsaclisib, and luspatercept.

Ruxolitinib as a Novel Therapeutic Option for Poor Prognosis T-LBL Pediatric Patients

Simple Summary

Current treatment protocols for pediatric patients with T-Lymphoblastic lymphoma (T-LBL) allow the achievement of a complete remission in around 85% of T-LBL pediatric patients; however the overall survival rate of second-line treatments for patients with progressive disease or relapse is around 14%. Thus, the major issues to be addressed are the identification of a valuable predictor marker to foresee the disease risk and new therapeutic targets to improve relapsed/resistant patients’ outcome. We identified JAK2 Y1007-1008 as a potential prognosis marker as well as a therapeutic target for patients with progressive disease or relapse and suggest that its inhibition by ruxolitinib, a JAK1/2 FDA approved inhibitor, could represent a novel therapeutic approach to overcome therapy resistance and meliorate the outcome of pediatric T-LBL patients.

Abstract

Lymphoblastic lymphoma (LBL) is the second most common type of non-Hodgkin lymphoma in childhood, mainly of T cell origin (T-LBL). Although current treatment protocols allow a complete remission in 85% of cases, the second-line treatment overall survival for patients with progressive or relapsed disease is around 14%, making this the major issue to be confronted. Thus, we performed a Reverse Phase Protein Array study in a cohort of 22 T-LBL patients to find reliable disease risk marker(s) and new therapeutic targets to improve pediatric T-LBL patients’ outcome. Interestingly, we pinpointed JAK2 Y1007-1008 as a potential prognosis marker as well as a therapeutic target in poor prognosis patients. Hence, the hyperactivation of the JAK1/2-STAT6 pathway characterizes these latter patients. Moreover, we functionally demonstrated that STAT6 hyperactivation contributes to therapy resistance by binding the glucocorticoid receptor, thus inhibiting its transcriptional activity. This was further confirmed by specific STAT6 gene silencing followed by dexamethasone treatment. Finally, JAK1/2-STAT6 pathway inhibition by ruxolitinib, an FDA approved drug, in cell line models and in one T-LBL primary sample led to cell proliferation reduction and increased apoptosis. Globally, our results identify a new potential prognostic marker and suggest a novel therapeutic approach to overcome therapy resistance in pediatric T-LBL patients.

Untwining Anti-Tumor and Immunosuppressive Effects of JAK Inhibitors-A Strategy for Hematological Malignancies?

Simple Summary

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway is aberrantly activated in many malignancies. Inhibition of this pathway via JAK inhibitors (JAKinibs) is therefore an attractive therapeutic strategy underlined by Ruxolitinib (JAK1/2 inhibitor) being approved for the treatment of myeloproliferative neoplasms. As a consequence of the crucial role of the JAK-STAT pathway in the regulation of immune responses, inhibition of JAKs suppresses the immune system. This review article provides a thorough overview of the current knowledge on JAKinibs’ effects on immune cells in the context of hematological malignancies. We also discuss the potential use of JAKinibs for the treatment of diseases in which lymphocytes are the source of the malignancy.

Abstract

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway propagates signals from a variety of cytokines, contributing to cellular responses in health and disease. Gain of function mutations in JAKs or STATs are associated with malignancies, with JAK2^V617F being the main driver mutation in myeloproliferative neoplasms (MPN). Therefore, inhibition of this pathway is an attractive therapeutic strategy for different types of cancer. Numerous JAK inhibitors (JAKinibs) have entered clinical trials, including the JAK1/2 inhibitor Ruxolitinib approved for the treatment of MPN. Importantly, loss of function mutations in JAK-STAT members are a cause of immune suppression or deficiencies. MPN patients undergoing Ruxolitinib treatment are more susceptible to infections and secondary malignancies. This highlights the suppressive effects of JAKinibs on immune responses, which renders them successful in the treatment of autoimmune diseases but potentially detrimental for cancer patients. Here, we review the current knowledge on the effects of JAKinibs on immune cells in the context of hematological malignancies. Furthermore, we discuss the potential use of JAKinibs for the treatment of diseases in which lymphocytes are the source of malignancies. In summary, this review underlines the necessity of a robust immune profiling to provide the best benefit for JAKinib-treated patients.

Rational modification, synthesis and biological evaluation of N-substituted phthalazinone derivatives designed to target interleukine-15 protein

Interleukin (IL)-15 is a pleiotropic cytokine structurally close to IL-2 and sharing with the IL-2Rβ and γc receptor (R) subunits. IL-15 plays important roles in innate and adaptative immunity, supporting the activation and proliferation of NK, NK-T, and CD8⁺ T cells. Over-expression of IL-15 has been shown to participate to the development of inflammatory and autoimmune diseases and diverse T cell malignancies. This study is in continuity of our previous work through which a family of small-molecule inhibitors impeding IL-15/IL-2Rβ interaction with sub-micromolar activity has been identified using pharmacophore-based virtual screening and hit optimization methods. With the aim to improve the efficacy and selectivity of our lead inhibitor, specific modifications have been introduced on the basis of optimized SAR and modelisation. The new series of compounds generated have been evaluated for their capacity to inhibit the proliferation as well as the down-stream signaling of IL-15-dependent cells and to bind to IL-15.

CXCR4 allows T cell acute lymphoblastic leukemia to escape from JAK1/2 and BCL2 inhibition through CNS infiltration

Targeting the JAK/STAT and BCL2 pathways in patients with relapsed/refractory T cell acute lymphoblastic leukemia (T-ALL) may provide an alternative approach to achieve clinical remissions. Ruxolitinib and venetoclax show a dose-dependent effect on T-ALL individually, but combination treatment reduces survival and proliferation of T-ALL in vitro. Using a xenograft model, the combination treatment fails to improve survival, with death from hind limb paralysis. Despite on-target inhibition by the drugs, histopathology demonstrates increased leukemic infiltration into the central nervous system (CNS) as compared to liver or bone marrow. Liquid chromatography-tandem mass spectroscopy shows that ruxolitinib and venetoclax insufficiently cross into the CNS. The addition of the CXCR4 inhibitor plerixafor with ruxolitinib and venetoclax reduces clinical scores and enhances survival. While combination therapy with ruxolitinib and venetoclax shows promise for treating T-ALL, additional inhibition of the CXCR4-CXCL12 axis may be needed to maximize the possibility of complete remission.

The Role of Bcl-xL Protein in Viral Infections

Bcl-xL represents a family of proteins responsible for the regulation of the intrinsic apoptosis pathway. Due to its anti-apoptotic activity, Bcl-xL co-determines the viability of various virally infected cells. Their survival may determine the effectiveness of viral replication and spread, dynamics of systemic infection, and viral pathogenesis. In this paper, we have reviewed the role of Bcl-xL in the context of host infection by eight different RNA and DNA viruses: hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), influenza A virus (IAV), Epstein-Barr virus (EBV), human T-lymphotropic virus type-1 (HTLV-1), Maraba virus (MRBV), Schmallenberg virus (SBV) and coronavirus (CoV). We have described an influence of viral infection on the intracellular level of Bcl-xL and discussed the impact of Bcl-xL-dependent cell survival control on infection-accompanying pathogenic events such as tissue damage or oncogenesis. We have also presented anti-viral treatment strategies based on the pharmacological regulation of Bcl-xL expression or activity.

Exploring Dysregulated Signaling Pathways in Cancer

Cancer cell biology takes advantage of identifying diverse cellular signaling pathways that are disrupted in cancer. Signaling pathways are an important means of communication from the exterior of cell to intracellular mediators, as well as intracellular interactions that govern diverse cellular processes. Oncogenic mutations or abnormal expression of signaling components disrupt the regulatory networks that govern cell function, thus enabling tumor cells to undergo dysregulated mitogenesis, to resist apoptosis, and to promote invasion to neighboring tissues. Unraveling of dysregulated signaling pathways may advance the understanding of tumor pathophysiology and lead to the improvement of targeted tumor therapy. In this review article, different signaling pathways and how their dysregulation contributes to the development of tumors have been discussed.

Enhanced efficacy of JAK1 inhibitor with mTORC1/C2 targeting in smoldering/chronic adult T cell leukemia

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IL-2Rα is expressed in the leukemic cells of smoldering/chronic ATL patients, leading to activation of the JAK/STAT pathway.

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JAK1 inhibition with Upadacitinib inhibited cell proliferation and phosphorylation of STAT5 in cytokine-dependent ATL model.

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Dual mTORC1/C2 inhibitor was more effective than the single mTORC1 inhibitor in the cytokine-dependent ATL model.

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The combination of JAKi and mTORi showed synergistic effect in xenografts and leukemic cells from smoldering/chronic ATL.

Adult T-cell leukemia (ATL) is an aggressive T-cell lymphoproliferative malignancy of regulatory T lymphocytes (Tregs), caused by human T-cell lymphotropic virus 1 (HTLV-1). Interleukin 2 receptor alpha (IL-2Rα) is expressed in the leukemic cells of smoldering/chronic ATL patients, leading to constitutive activation of the JAK/STAT pathway and spontaneous proliferation. The PI3K/AKT/mTOR pathway also plays a critical role in ATL cell survival and proliferation. We previously performed a high-throughput screen that demonstrated additive/synergistic activity of Ruxolitinib, a JAK1/2 inhibitor, with AZD8055, an mTORC1/C2 inhibitor. However, effects of unintended JAK2 inhibition with Ruxolitinib limits it therapeutic potential for ATL patients, which lead us to evaluate a JAK1-specific inhibitor. Here, we demonstrated that Upadacitinib, a JAK-1 inhibitor, inhibited the proliferation of cytokine-dependent ATL cell lines and the expression of p-STAT5. Combinations of Upadacitinib with either AZD8055 or Sapanisertib, mTORC1/C2 inhibitors, showed anti-proliferative effects against cytokine-dependent ATL cell lines and synergistic effect with reducing tumor growth in NSG mice bearing IL-2 transgenic tumors. Importantly, the combination of these two agents inhibited ex vivo spontaneous proliferation of ATL cells from patients with smoldering/chronic ATL. Combined targeting of JAK/STAT and PI3K/AKT/mTOR pathways represents a promising therapeutic intervention for patients with smoldering/chronic ATL.

Expression changes of cytotoxicity and apoptosis genes in HTLV-1-associated myelopathy/tropical spastic paraparesis patients from the perspective of system virology

Although human T-cell lymphotropic virus type-1 (HTLV-1) was the first retrovirus among human pathogens to be identified, insufficient information on the pathogenesis of HTLV-1 infection means that no precise mechanism has yet been provided for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Based on previous studies, it was found that apoptosis and inflammation stimulation were among the most important mechanisms underlying HAM/TSP. The present study provides an in-silico analysis of the microarray data related to HAM/TSP patients. Expression changes of the genes responsible for cytotoxicity and apoptosis processes of HAM/TSP patients and asymptomatic carriers were investigated. Expression of the genes involved in cytotoxicity and apoptosis in HAM/TSP patients was decreased; hence, a model was proposed indicating that the spread of immune responses in HAM/TSP may be due to expression of HTLV-1 virulence factors and the resistance of HTLV-1-infected cells to apoptosis.

Interleukin-15 (dys)regulation of lymphoid homeostasis: Implications for therapy of autoimmunity and cancer

IL-15 supports NK, NK-T, γδ, ILC1, and memory CD8 T cell function, and dysregulated IL-15 is associated with many autoimmune diseases. Striking IL-15–driven increases in NK and CD8 T cells in patients highlight the potential for combination therapy of cancers.

IL-15, a pleiotropic cytokine, stimulates generation of NK, NK-T, γδ, ILC1, and memory CD8 T cells. IL-15 disorders play pathogenetic roles in organ-specific autoimmune diseases including celiac disease. Diverse approaches are developed to block IL-15 action. IL-15 administered to patients with malignancy yielded dramatic increases in NK numbers and modest increases in CD8 T cells. Due to immunological checkpoints, to achieve major cancer therapeutic efficacy, IL-15 will be used in combination therapy, and combination trials with checkpoint inhibitors, with anti-CD40 to yield tumor-specific CD8 T cells, and with anticancer monoclonal antibodies to increase ADCC and antitumor efficacy, have been initiated.

Mechanisms of Oncogenesis by HTLV-1 Tax

The human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATLL), a neoplasm of CD4+CD25+ T cells that occurs in 2-5% of infected individuals after decades of asymptomatic latent infection. Multiple HTLV-1-encoded regulatory proteins, including Tax and HTLV-1 basic leucine zipper factor (HBZ), play key roles in viral persistence and latency. The HTLV-1 Tax oncoprotein interacts with a plethora of host cellular proteins to regulate viral gene expression and also promote the aberrant activation of signaling pathways such as NF-κB to drive clonal proliferation and survival of T cells bearing the HTLV-1 provirus. Tax undergoes various post-translational modifications such as phosphorylation and ubiquitination that regulate its function and subcellular localization. Tax shuttles in different subcellular compartments for the activation of anti-apoptotic genes and deregulates the cell cycle with the induction of DNA damage for the accumulation of genomic instability that can result in cellular immortalization and malignant transformation. However, Tax is highly immunogenic and therefore HTLV-1 has evolved numerous strategies to tightly regulate Tax expression while maintaining the pool of anti-apoptotic genes through HBZ. In this review, we summarize the key findings on the oncogenic mechanisms used by Tax that set the stage for the development of ATLL, and the strategies used by HTLV-1 to tightly regulate Tax expression for immune evasion and viral persistence.

A high-throughput screening platform for Polycystic Kidney Disease (PKD) drug repurposing utilizing murine and human ADPKD cells

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common inherited monogenic disorders, characterized by a progressive decline in kidney function due in part to the formation of fluid-filled cysts. While there is one FDA-approved therapy, it is associated with potential adverse effects, and all other clinical interventions are largely supportive. Insights into the cellular pathways underlying ADPKD have revealed striking similarities to cancer. Moreover, several drugs originally developed for cancer have shown to ameliorate cyst formation and disease progression in animal models of ADPKD. These observations prompted us to develop a high-throughput screening platform of cancer drugs in a quest to repurpose them for ADPKD. We screened ~8,000 compounds, including compounds with oncological annotations, as well as FDA-approved drugs, and identified 155 that reduced the viability of Pkd1-null mouse kidney cells with minimal effects on wild-type cells. We found that 109 of these compounds also reduced in vitro cyst growth of Pkd1-null cells cultured in a 3D matrix. Moreover, the result of the cyst assay identified therapeutically relevant compounds, including agents that interfere with tubulin dynamics and reduced cyst growth without affecting cell viability. Because it is known that several ADPKD therapies with promising outcomes in animal models failed to be translated to human disease, our platform also incorporated the evaluation of compounds in a panel of primary ADPKD and normal human kidney (NHK) epithelial cells. Although we observed differences in compound response amongst ADPKD and NHK cell preparation, we identified 18 compounds that preferentially affected the viability of most ADPKD cells with minimal effects on NHK cells. Our study identifies attractive candidates for future efficacy studies in advanced pre-clinical models of ADPKD.

IL-2/IL-2 Receptor Pathway Plays a Crucial Role in the Growth and Malignant Transformation of HTLV-1-Infected T Cells to Develop Adult T-Cell Leukemia

T cells infected with human T-cell leukemia virus type 1 (HTLV-1) transform into malignant/leukemic cells and develop adult T-cell leukemia (ATL) after a long latency period. The tax (transactivator from the X-gene region) and HBZ (HTLV-1 bZIP factor) genes of HTLV-1 play crucial roles in the development of ATL. The process and mechanism by which HTLV-1-infected T cells acquire malignancy and develop ATL remain to be elucidated. Constitutive expression of interleukin-2 (IL-2) receptor α-chain (IL-2Rα/CD25), induced by the tax and HBZ genes of HTLV-1, on ATL cells implicates the involvement of IL-2/IL-2R pathway in the growth and development of ATL cells in vivo. However, the leukemic cells in the majority of ATL patients appeared unresponsive to IL-2, raising controversies on the role of this pathway for the growth of ATL cells in vivo. Here, we report the establishment of 32 IL-2-dependent T-cell lines infected with HTLV-1 from 26 ATL patients, including eight leukemic cell lines derived from five ATL patients, while no T-cell lines were established without IL-2. We have shown that the IL-2-dependent ATL cell lines evolved into IL-2-independent/-unresponsive growth phase, resembling ATL cells in vivo. Moreover, the IL-2-dependent non-leukemic T-cell lines infected with HTLV-1 acquired IL-2-independency and turned into tumor-producing cancer cells as with the ATL cell lines. HTLV-1-infected T cells in vivo could survive and proliferate depending on IL-2 that was produced in vivo by the HTLV-1-infected T cells of ATL patients and patients with HTLV-1-associated diseases and, acts as a physiological molecule to regulate T-cell growth. These results suggest that ATL cells develop among the HTLV-1-infected T cells growing dependently on IL-2 and that most of the circulating ATL cells progressed to become less responsive to IL-2, acquiring the ability to proliferate without IL-2.

Advances in targeted therapy for malignant lymphoma

The incidence of lymphoma has gradually increased over previous decades, and it ranks among the ten most prevalent cancers worldwide. With the development of targeted therapeutic strategies, though a subset of lymphoma patients has become curable, the treatment of refractory and relapsed diseases remains challenging. Many efforts have been made to explore new targets and to develop corresponding therapies. In addition to novel antibodies targeting surface antigens and small molecular inhibitors targeting oncogenic signaling pathways and tumor suppressors, immune checkpoint inhibitors and chimeric antigen receptor T-cells have been rapidly developed to target the tumor microenvironment. Although these targeted agents have shown great success in treating lymphoma patients, adverse events should be noted. The selection of the most suitable candidates, optimal dosage, and effective combinations warrant further investigation. In this review, we systematically outlined the advances in targeted therapy for malignant lymphoma, providing a clinical rationale for mechanism-based lymphoma treatment in the era of precision medicine.

High activation of STAT5A drives peripheral T-cell lymphoma and leukemia

Recurrent gain-of-function mutations in the transcription factors STAT5A and much more in STAT5B were found in hematopoietic malignancies with the highest proportion in mature T- and natural killer-cell neoplasms (peripheral T-cell lymphoma, PTCL). No targeted therapy exists for these heterogeneous and often aggressive diseases. Given the shortage of models for PTCL, we mimicked graded STAT5A or STAT5B activity by expressing hyperactive Stat5a or STAT5B variants at low or high levels in the hematopoietic system of transgenic mice. Only mice with high activity levels developed a lethal disease resembling human PTCL. Neoplasia displayed massive expansion of CD8⁺ T cells and destructive organ infiltration. T cells were cytokine-hypersensitive with activated memory CD8⁺ T-lymphocyte characteristics. Histopathology and mRNA expression profiles revealed close correlation with distinct subtypes of PTCL. Pronounced STAT5 expression and activity in samples from patients with different subsets underline the relevance of JAK/STAT as a therapeutic target. JAK inhibitors or a selective STAT5 SH₂ domain inhibitor induced cell death and ruxolitinib blocked T-cell neoplasia in vivo. We conclude that enhanced STAT5A or STAT5B action both drive PTCL development, defining both STAT5 molecules as targets for therapeutic intervention.

STAT3 Activation and Oncogenesis in Lymphoma

Signal transducer and activator of transcription 3 (STAT3) is an important and the most studied transcription factor in the Janus kinase (JAK)/STAT signaling pathway. STAT3 mediates the expression of various genes that play a critical role in many cellular and biological processes, such as cell proliferation, survival, differentiation, migration, angiogenesis, and inflammation. STAT3 and associated JAKs are activated and tightly regulated by a variety of cytokines and growth factors and their receptors in normal immune responses. However, abnormal expression of STAT3 leads to its constitutive activation, which promotes malignant transformation and tumor progression through oncogenic gene expression in numerous human cancers. Human lymphoma is a heterogeneous malignancy of T and B lymphocytes. Constitutive signaling by STAT3 is an oncogenic driver in several types of B-cell lymphoma and most of T-cell lymphomas. Aberrant STAT3 activation can also induce inappropriate expression of genes involved in tumor immune evasion such as PD-L1. In this review, we focus on the oncogenic role of STAT3 in human lymphoma and highlight potential therapeutic intervention by targeting JAK/STAT3 signaling.

Rapid progression of adult T-cell leukemia/lymphoma as tumor-infiltrating Tregs after PD-1 blockade

Immune checkpoint inhibitors are a powerful new tool in the treatment of cancer, with prolonged responses in multiple diseases, including hematologic malignancies, such as Hodgkin lymphoma. However, in a recent report, we demonstrated that the PD-1 inhibitor nivolumab led to rapid progression in patients with adult T-cell leukemia/lymphoma (ATLL) (NCT02631746). We obtained primary cells from these patients to determine the cause of this hyperprogression. Analyses of clonality, somatic mutations, and gene expression in the malignant cells confirmed the report of rapid clonal expansion after PD-1 blockade in these patients, revealed a previously unappreciated origin of these malignant cells, identified a novel connection between ATLL cells and tumor-resident regulatory T cells (Tregs), and exposed a tumor-suppressive role for PD-1 in ATLL. Identifying the mechanisms driving this alarming outcome in nivolumab-treated ATLL may be broadly informative for the growing problem of rapid progression with immune checkpoint therapies.

Biomarkers and Preclinical Models for Adult T-Cell Leukemia-Lymphoma Treatment

Adult T-cell leukemia/lymphoma (ATL) is an aggressive lymphoproliferative malignancy with a very poor prognosis. Despite several recent advances, new therapeutic approaches are critical, and this will require successful preclinical studies, including studies in ATL cell culture systems, and mouse models. Identification of accurate, reproducible biomarkers will be a crucial component of preclinical and clinical studies. This review summarizes the current state-of-the-art in each of these fields, and provides recommendations for future approaches. This problem is an important unmet need in HTLV research.

You Cannot Have Your Synergy and Efficacy Too

Synergistic drugs are preferred in combination therapies for many diseases, including viral infections and cancers. Maximizing synergy, however, may come at the cost of efficacy. This synergy-efficacy trade-off appears to be widely prevalent and independent of the specific drug interactions yielding synergy. We present examples of the trade-off in drug combinations used in hepatitis C, HIV, and cancer therapies and believe that screens for optimal drug combinations that presently seek to maximize synergy may be improved by considering the trade-off.

Phosphorylated STAT3 expression predicts better prognosis in smoldering type of adult T-cell leukemia/lymphoma

Adult T‐cell leukemia/lymphoma (ATLL) is a mature T‐cell neoplasm, and is divided into 2 indolent (smoldering and chronic) and 2 aggressive (acute and lymphoma) clinical subtypes. Based on previous integrated molecular analyses suggesting the importance of the JAK‐STAT pathway in ATLL, we attempted to clarify the clinicopathological significance of this pathway. Clinical and morphological findings were reviewed in 116 cases with ATLL. The nuclear localizations of phosphorylated STAT3 (pSTAT3), pSTAT5, and pSTAT6 were analyzed by immunohistochemistry. Targeted sequencing was undertaken on the portion of STAT3 encoding the Src homology 2 domain. Expression of pSTAT3 was observed in 43% (50/116) of ATLL cases, whereas pSTAT5 and pSTAT6 were largely undetected. Cases with the lymphoma type showed significantly less frequent pSTAT3 expression (8/45, 18%) than those with the other subtypes (41/66, 62%; P < .001). STAT3 mutations were detected in 36% (10/28) and 19% (12/64) of cases with the smoldering and aggressive types of ATLL, respectively. The correlation between STAT3 mutation and pSTAT3 expression was not significant (P = .07). Both univariate and multivariate analysis revealed that pSTAT3 expression was significantly associated with better overall survival and progression‐free survival in the smoldering type of ATLL, whereas STAT3 mutation was not related to a line of clinical outcome. Collectively, our data show that only the lymphoma type showed a low prevalence of tumor cells positive for pSTAT3 expression, and raises the possibility that pSTAT3 expression is a novel biomarker to predict better prognosis in the smoldering type of ATLL.

Advances in computational approaches in identifying synergistic drug combinations

Accumulated empirical clinical experience, supported by animal or cell line models, has initiated efforts of predicting synergistic combinatorial drugs with more-than-additive effect compared with the sum of the individual agents. Aiming to construct better computational models, this review started from the latest updated data resources of combinatorial drugs, then summarized the reported mechanism of the known synergistic combinations from aspects of drug molecular and pharmacological patterns, target network properties and compound functional annotation. Based on above, we focused on the main in silico strategies recently published, covering methods of molecular modeling, mathematical simulation, optimization of combinatorial targets and pattern-based statistical/learning model. Future thoughts are also discussed related to the role of natural compounds, drug combination with immunotherapy and management of adverse effects. Overall, with particular emphasis on mechanism of action of drug synergy, this review may serve as a rapid reference to design improved models for combinational drugs.

BMPRII deficiency impairs apoptosis via the BMPRII-ALK1-BclX-mediated pathway in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a devastating cardiovascular disorder characterized by the remodelling of pre-capillary pulmonary arteries. The vascular remodelling observed in PAH patients results from excessive proliferation and apoptosis resistance of pulmonary arterial smooth muscle cells (PASMCs) and pulmonary arterial endothelial cells (PAECs). We have previously demonstrated that mutations in the type II receptor for bone morphogenetic protein (BMPRII) underlie the majority of the familial and inherited forms of the disease. We have further demonstrated that BMPRII deficiency promotes excessive proliferation and attenuates apoptosis in PASMCs, but the underlying mechanisms remain unclear. The major objective of this study is to investigate how BMPRII deficiency impairs apoptosis in PAH. Using multidisciplinary approaches, we demonstrate that deficiency in the expression of BMPRII impairs apoptosis by modulating the alternative splicing of the apoptotic regulator, B-cell lymphoma X (Bcl-x) transcripts: a finding observed in circulating leukocytes and lungs of PAH subjects, hypoxia-induced PAH rat lungs as well as in PASMCs and PAECs. BMPRII deficiency elicits cell specific effects: promoting the expression of Bcl-xL transcripts in PASMCs while inhibiting it in ECs, thus exerting differential apoptotic effects in these cells. The pro-survival effect of BMPRII receptor is mediated through the activin receptor-like kinase 1 (ALK1) but not the ALK3 receptor. Finally, we show that BMPRII interacts with the ALK1 receptor and pathogenic mutations in the BMPR2 gene abolish this interaction. Taken together, dysfunctional BMPRII responsiveness impairs apoptosis via the BMPRII-ALK1-Bcl-xL pathway in PAH. We suggest Bcl-xL as a potential biomarker and druggable target.

IL-2 and IL-15 blockade by BNZ-1, an inhibitor of selective γ-chain cytokines, decreases leukemic T-cell viability

Interleukin-15 (IL-15) and IL-2 drive T-cell malignancies including T-cell large granular lymphocyte leukemia (T-LGLL) and HTLV-1 driven adult T-cell leukemia (ATL). Both cytokines share common γ-chain receptors and downstream signaling pathways. T-LGLL is characterized by clonal expansion of cytotoxic T cells and is associated with abnormal JAK/STAT signaling. ATL is an aggressive CD4+ T-cell neoplasm associated with HTLV-1. T-LGLL and ATL share dependence on IL-2 and IL-15 for survival and both diseases lack effective therapies. BNZ-1 is a pegylated peptide designed to specifically bind the γc receptor to selectively block IL-2, IL-15, and IL-9 signaling. We hypothesized that treatment with BNZ-1 would reduce cytokine-mediated proliferation and viability. Our results demonstrated that in vitro treatment of a T-LGLL cell line and ex vivo treatment of T-LGLL patient cells with BNZ-1 inhibited cytokine-mediated viability. Furthermore, BNZ-1 blocked downstream signaling and increased apoptosis. These results were mirrored in an ATL cell line and in ex vivo ATL patient cells. Lastly, BNZ-1 drastically reduced leukemic burden in an IL-15-driven human ATL mouse xenograft model. Thus, BNZ-1 shows great promise as a novel therapy for T-LGLL, ATL, and other IL-2 or IL-15 driven hematopoietic malignancies.

PAK Kinase Inhibition Has Therapeutic Activity in Novel Preclinical Models of Adult T-Cell Leukemia/Lymphoma

PURPOSE

To evaluate therapeutic activity of PAK inhibition in ATLL and to characterize the role of PAK isoforms in cell proliferation, survival, and adhesion of ATLL cells in preclinical models.

EXPERIMENTAL DESIGN

Frequency and prognostic impact of PAK2 amplification were evaluated in an ATLL cohort of 370 cases. Novel long-term cultures and in vivo xenograft models were developed using primary ATLL cells from North American patients. Two PAK inhibitors were used to block PAK kinase activity pharmacologically. siRNA-based gene silencing approach was used to genetically knockdown (KD) PAK1 and PAK2 in ATLL cell lines.

RESULTS

PAK1/2/4 are the three most abundantly expressed PAK family members in ATLL. PAK2 amplifications are seen in 24% of ATLLs and are associated with worse prognosis in a large patient cohort. The pan-PAK inhibitor PF-3758309 (PF) has strong in vitro and in vivo activity in a variety of ATLL preclinical models. These activities of PF are likely attributed to its ability to target several PAK isoforms simultaneously because genetic silencing of either PAK1 or PAK2 produced more modest effects. PAK2 plays a major role in CADM1-mediated stromal interaction, which is an important step in systemic dissemination of the disease. This finding is consistent with the observation that PAK2 amplification is more frequent in aggressive ATLLs and correlates with inferior outcome.

CONCLUSIONS

PAK2, a gene frequently amplified in ATLL, facilitates CADM1-mediated stromal interaction and promotes survival of ATLL cells. Taken together, PAK inhibition may hold significant promise as a targeted therapy for aggressive ATLLs.

Oxymatrine exhibits anti-tumor activity in gastric cancer through inhibition of IL-21R-mediated JAK2/STAT3 pathway

Oxymatrine (OMT) as a type of alkaloids collected from Sophora flavescens Ait exerts some biological functions including anticancer properties. Here, we investigated the therapeutic effects of OMT in gastric cancer cells (HGC 27 and AGS). As a result, the exposure of gastric cancer (GC) cells to OMT contributed to the suppression of cell proliferation and invasion. Interleukin 21 receptor (IL-21R) was identified to be differentially expressed between OMT treatment group (4 mg/mL) and control group (0 mg/mL), and knockdown of IL-21R repressed cell proliferation and invasion via inactivation of the JAK2/STAT3 pathway. The rescue experiment showed that IL-21R overexpression attenuated the anti-tumor effects of OMT through activation of the JAK2/STAT3 pathway. Moreover, the expression of IL-21R was significantly upregulated in GC samples compared with the adjacent normal tissues and associated with overall survival (OS) and tumor recurrence of GC patients. Taken together, in this study, we evaluated the anti-tumor effects of OMT on GC by investigating proliferation and invasion ability changes, and our findings show that OMT exhibits effects via regulation of JAK/STAT signaling pathway. Through the mechanism study, we may enlighten the potential therapeutic target for treatment of GC.

IL-21R functions as an oncogenic factor and is regulated by the lncRNA MALAT1/miR-125a-3p axis in gastric cancer

Interleukin-21 receptor (IL-21R) is involved in the immunological regulation of immune cells and tumor progression in multiple malignancies. However, the potential molecular mechanisms through which non-coding RNAs (ncRNAs) modulate IL-21R signaling in gastric cancer (GC) remain elusive. In this study, the expression of IL-21R was detected by RT-qPCR and western blot analysis in GC cell lines. The association between IL-21R expression and clinicopathological characteristics and the prognosis of patients with GC was analyzed by immunohistochemistry and Kaplan-Meier plotter analysis. The biological functions of IL-21R were analyzed by a series of in vitro and in vivo experiments, and its regulation by ncRNAs was predicted by bioinformatics analysis and confirmed by luciferase assays and rescue experiments. As a result, the expression of IL-21R was found to be significantly increased in GC cell lines and tissues as compared with normal tissues, and was associated with tumor size and lymphatic metastasis, acting as an independent prognostic factor of poor survival and recurrence in patients with GC. The knockdown of IL-21R markedly suppressed GC cell proliferation and invasion, and IL-21R expression was further validated to be negatively regulated by miR-125a-3p (miR-125a). The overexpression of IL-21R reversed the tumor suppressive effects of miR-125a in vitro and in vivo. Moreover, lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) acted as a sponge of miR-125a to modulate the IL-21R signaling pathway in GC cells and represented a risk factor for survival and recurrence in patients with GC. Taken together, the findings of this study reveal an oncogenic role for IL-21R in gastric tumorigenesis and verify that its activation is partly due to the dysregulation of the lncRNA MALAT1/miR-125a axis. These findings may provide a potential prognostic marker for patients with GC.