Persistent STAT5 activation in myeloid neoplasms recruits p53 into gene regulation

Regulation of STAT5 phosphorylation and interaction with SHP1 by lnc-AC004893, a long non-coding RNA overexpressed in myeloproliferative neoplasms

OBJECTIVES

Constitutive activation of Janus kinase 2 (JAK2)/signal transducer and activator of transcription (STAT) signaling pathway is central to the pathogenesis of myeloproliferative neoplasms (MPNs). Long noncoding RNAs (lncRNAs) regulate diverse biological processes. However, the role of lncRNAs in MPN pathogenesis is not well studied.

METHODS

The expression of lnc-AC004893 in MPN patients was measured by quantitative real-time PCR (qRT-PCR). Gene-specific short hairpin RNAs (shRNAs) were designed to inhibit the expression of lnc-AC004893, and western blot was performed to explore the role of lnc-AC004893 via regulating the JAK2/STAT5 signaling pathway. Furthermore, co-IP was performed to determine the binding ability of lnc-AC004893 and STAT5 protein. Finally, the BaF3-JAK2V617F-transplanted mouse model was used to assess the biological role of lnc-ac004893 in vivo.

RESULTS

We report that lnc-AC004893, a poorly conserved pseudogene-209, is substantially upregulated in MPN cells compared with normal controls (NCs). Knockdown of lnc-AC004893 by specific shRNAs suppressed cell proliferation and decreased colony formation. Furthermore, the knockdown of lnc-AC004893 reduced the expression of p-STAT5 but not total STAT5 in HEL and murine IL-3-dependent Ba/F3 cells, which present constitutive and inducible activation of JAK2/STAT5 signaling. In addition, inhibition of murine lnc-ac004893 attenuated BaF3-JAK2V617F-transplanted phenotypes and extended the overall survival. Mechanistically, knockdown of lnc-AC004893 enhanced the binding ability of STAT5 and protein tyrosine phosphatase SHP1. Furthermore, knockdown of lnc-AC004893 decreased STAT5-lnc-AC004893 interaction but not SHP1-lnc-AC004893 interaction.

CONCLUSION

Lnc-AC004893 regulates STAT5 phosphorylation by affecting the interaction of STAT5 and SHP1. Lnc-AC004893 might be a potential therapeutic target for MPN patients.

TEP RNA: a new frontier for early diagnosis of NSCLC

BACKGROUND

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer (LC), which is the leading cause of tumor mortality. In recent years, compared with tissue biopsy, which is the diagnostic gold standard for tumor diagnosis, Liquid biopsy (LB) is considered to be a more minimally invasive, sensitive, and safer alternative or auxiliary diagnostic method. However, the current value of LB in early diagnosis of LC is not ideal, so it is particularly important to study the changes in blood composition during the process of tumorigenesis and find more sensitive biomarkers.

PURPOSE

Platelets are a type of abundant blood cells that carry a large amount of RNA. In the LC regulatory network, activated platelets play an important role in the process of tumorigenesis, development, and metastasis. In order to identify predictive liquid biopsy biomarkers for the diagnosis of NSCLC, we summarized the development and function of platelets, the interaction between platelets and tumors, the value of TEP RNA in diagnosis, prognosis, and treatment of NSCLC, and the method for detecting TEP RNA of NSCLC in this article.

CONCLUSION

The application of platelets in the diagnosis and treatment of NSCLC remains at a nascent stage. In addition to the drawbacks of low platelet count and complex experimental processes, the diagnostic accuracy of TEP RNA-seq for cancer in different populations still needs to be improved and validated. At present, a large number of studies have confirmed significant differences in the expression of TEP RNA in platelets between NSCLC patients and healthy individuals. Continuous exploration of the diagnostic value of TEP RNA in NSCLC is of utmost importance. The integration of NSCLC platelet-related markers with other NSCLC markers can improve current tumor diagnosis and prognostic evaluation systems, providing broad prospects in tumor screening, disease monitoring, and prognosis assessment.

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.

Genomic and functional impact of Trp53 inactivation in JAK2V617F myeloproliferative neoplasms

Classical myeloproliferative neoplasms (MPNs) are characterized by the proliferation of myeloid cells and the risk of transformation into myelofibrosis or acute myeloid leukemia (AML) and TP53 mutations in MPN patients are linked to AML. However, JAK2V617F has been reported to impact the TP53 response to DNA damage, suggesting potential overlapping role of TP53 inactivation in MPN. We established a mouse model showing that JAK2V617F/Vav-Cre/Trp53-/- mice displayed a similar phenotype to JAK2V617F/Vav-Cre mice, but their proliferation was outcompeted in competitive grafts. RNA-Seq revealed that half of the genes affected by JAK2V617F were affected by p53-inactivation, including the interferon pathway. To validate this finding, mice were repopulated with a mixture of wild-type and JAK2V617F (or JAK2V617F/Vav-Cre/Trp53-/-) cells and treated with pegylated interferonα. JAK2V617F-reconstituted mice entered complete hematological remission, while JAK2V617F/Vav-Cre /Trp53-/--reconstituted mice did not, confirming that p53 loss induced interferon-α resistance. KEGG and Gene Ontology analyses of common deregulated genes showed that these genes were mainly implicated in cytokine response, proliferation, and leukemia evolution, illustrating that in this mouse model, the development of MPN is not affected by TP53 inactivation. Taken together, our results show that many genetic modifications induced by JAK2V617F are influenced by TP53, the MPN phenotype may not be. Trp53 loss alone is insufficient to induce rapid leukemic transformation in steady-state hematopoiesis in JAK2V617F MPN, and Trp53 loss may contribute to interferon resistance in MPN.

Chromothripsis orchestrates leukemic transformation in blast phase MPN through targetable amplification of DYRK1A

Chromothripsis, the process of catastrophic shattering and haphazard repair of chromosomes, is a common event in cancer. Whether chromothripsis might constitute an actionable molecular event amenable to therapeutic targeting remains an open question. We describe recurrent chromothripsis of chromosome 21 in a subset of patients in blast phase of a myeloproliferative neoplasm (BP-MPN), which alongside other structural variants leads to amplification of a region of chromosome 21 in ∼25% of patients ('chr21amp'). We report that chr21amp BP-MPN has a particularly aggressive and treatment-resistant phenotype. The chr21amp event is highly clonal and present throughout the hematopoietic hierarchy. DYRK1A , a serine threonine kinase and transcription factor, is the only gene in the 2.7Mb minimally amplified region which showed both increased expression and chromatin accessibility compared to non-chr21amp BP-MPN controls. We demonstrate that DYRK1A is a central node at the nexus of multiple cellular functions critical for BP-MPN development, including DNA repair, STAT signalling and BCL2 overexpression. DYRK1A is essential for BP-MPN cell proliferation in vitro and in vivo , and DYRK1A inhibition synergises with BCL2 targeting to induce BP-MPN cell apoptosis. Collectively, these findings define the chr21amp event as a prognostic biomarker in BP-MPN and link chromothripsis to a druggable target.

Boosting regulatory T cell-dependent immune tolerance by activation of p53

Regulatory T cells (Tregs) have critical roles in maintaining immune hemostasis and have important anti-inflammatory functions in diseases. Recently, we identified that CX-5461 (a selective RNA polymerase I inhibitor and p53 activator) acted as a potent immunosuppressive agent, which prevented allogeneic acute rejection in animal models via a molecular mechanism distinct from all those of conventional immunosuppressive drugs. Unexpectedly, we discovered that CX-5461 could promote Treg differentiation. In this review, we have summarized the evidence for a potential role of p53 in mediating Treg differentiation and its possible mechanisms, including regulation of FoxP3 transcription, regulation of the expression of PTEN (phosphatase and tensin homolog), as well as protein-protein interaction with the transcription factor STAT5 (signal transducer and activator of transcription 5). Evidence also suggests that pharmacological p53 activators may potentially be used to boost Treg-mediated immune tolerance. Based on these data, we argue that novel p53 activators such as CX-5461 may represent a distinct class of immunosuppressants that repress conventional T cell-mediated alloimmunity with concomitant boosting of Treg-dependent immune tolerance.

Lifetime Postnatal Exposure to Perfluoroalkyl Substance Mixture and DNA Methylation at Twelve Years of Age

Per- and polyfluoroalkyl substance (PFAS) exposure has been linked to DNA methylation changes in neonates and adults. We previously reported that prenatal PFAS exposure may have a durable impact on DNA methylation from birth to adolescence. However, few studies have examined the association of postnatal PFAS exposure with alterations in DNA methylation. We examined the associations of lifetime postnatal PFAS mixture exposure with leukocyte DNA methylation in 154 adolescents from the HOME Study (2003-2006; Cincinnati, Ohio). Lifetime postnatal PFAS mixture exposure was estimated using latent profile analysis of four PFAS concentrations measured at birth, and ages 3, 8, and 12 years. We measured DNA methylation in peripheral leukocytes at 12 years using the Illumina HumanMethylation EPIC BeadChip. We estimated covariate-adjusted associations between postnatal PFAS mixture concentrations and DNA methylation measures using linear regression, and used KEGG enrichment analysis to identify molecular pathways. Four significant differentially methylated positions were observed in the higher vs. lower PFAS profile (FDR p-value <0.05). These PFAS-associated CpG sites annotated to gene regions related to various cancers, cognition, and cardiometabolic health. We identified 17 pathways (FDR p-value <0.05), which indicates possible mechanism linking PFAS exposure to several health effects.

Ancistrocladinium A Induces Apoptosis in Proteasome Inhibitor-Resistant Multiple Myeloma Cells: A Promising Therapeutic Agent Candidate

The N,C-coupled naphthylisoquinoline alkaloid ancistrocladinium A belongs to a novel class of natural products with potent antiprotozoal activity. Its effects on tumor cells, however, have not yet been explored. We demonstrate the antitumor activity of ancistrocladinium A in multiple myeloma (MM), a yet incurable blood cancer that represents a model disease for adaptation to proteotoxic stress. Viability assays showed a potent apoptosis-inducing effect of ancistrocladinium A in MM cell lines, including those with proteasome inhibitor (PI) resistance, and in primary MM cells, but not in non-malignant blood cells. Concomitant treatment with the PI carfilzomib or the histone deacetylase inhibitor panobinostat strongly enhanced the ancistrocladinium A-induced apoptosis. Mass spectrometry with biotinylated ancistrocladinium A revealed significant enrichment of RNA-splicing-associated proteins. Affected RNA-splicing-associated pathways included genes involved in proteotoxic stress response, such as PSMB5-associated genes and the heat shock proteins HSP90 and HSP70. Furthermore, we found strong induction of ATF4 and the ATM/H2AX pathway, both of which are critically involved in the integrated cellular response following proteotoxic and oxidative stress. Taken together, our data indicate that ancistrocladinium A targets cellular stress regulation in MM and improves the therapeutic response to PIs or overcomes PI resistance, and thus may represent a promising potential therapeutic agent.

Differentiation-related genes in tumor-associated macrophages as potential prognostic biomarkers in non-small cell lung cancer

Background

The purpose of this study was to evaluate the role of differentiation-related genes (DRGs) in tumor-associated macrophages (TAMs) in non-small cell lung cancer (NSCLC).

Methods

Single cell RNA-seq (scRNA-seq) data from GEO and bulk RNA-seq data from TCGA were analyzed to identify DRGs using trajectory method. Functional gene analysis was carried out by GO/KEGG enrichment analysis. The mRNA and protein expression in human tissue were analyzed by HPA and GEPIA databases. To investigate the prognostic value of these genes, three risk score (RS) models in different pathological types of NSCLC were generated and predicted NSCLC prognosis in datasets from TCGA, UCSC and GEO databases.

Results

1,738 DRGs were identified through trajectory analysis. GO/KEGG analysis showed that these genes were predominantly related to myeloid leukocyte activation and leukocyte migration. 13 DRGs (C1QB, CCL4, CD14, CD84, FGL2, MS4A6A, NLRP3, PLEK, RNASE6, SAMSN1, SPN, TMEM176B, ZEB2) related to prognosis were obtained through univariate Cox analysis and Lasso regression. C1QB, CD84, FGL2, MS4A6A, NLRP3, PLEK, SAMSN1, SPN, and ZEB2 were downregulated in NSCLC compared to non-cancer tissue. The mRNA of 13 genes were significantly expressed in pulmonary macrophages with strong cell specificity. Meanwhile, immunohistochemical staining showed that C1QB, CCL4, SPN, CD14, NLRP3, SAMSN1, MS4A6A, TMEM176B were expressed in different degrees in lung cancer tissues. ZEB2 (HR=1.4, P&lt;0.05) and CD14 (HR=1.6, P&lt;0.05) expression were associated with a worse prognosis in lung squamous cell carcinoma; ZEB2 (HR=0.64, P&lt;0.05), CD84 (HR=0.65, P&lt;0.05), PLEK (HR=0.71, P&lt;0.05) and FGL2 (HR=0.61, P&lt;0.05) expression were associated with a better prognosis in lung adenocarcinoma. Three RS models based on 13 DRGs both showed that the high RS was significantly associated with poor prognosis in different pathological types of NSCLC.

Conclusions

This study highlights the prognostic value of DRGs in TAMs in NSCLC patients, providing novel insights for the development of therapeutic and prognostic targets based on TAM functional differences.

Combined treatment with ruxolitinib and MK-2206 inhibits the JAK2/STAT5 and PI3K/AKT pathways via apoptosis in MDA-MB-231 breast cancer cell line

BACKGROUND

Due to deficiencies in the expression of hormone receptors, such as PR, ER and HER2, it is challenging to treat triple-negative breast cancer, which does not respond to single targeted therapy. Ruxolitinib is a Janus kinase (JAK)1/JAK2 inhibitor. MK-2206 is an allosteric AKT inhibitor. Due to the limited activities of ruxolitinib and MK-2206 for monotherapy, the need for cotreatment with other drugs has emerged. This study is the first to examine the effects of ruxolitinib and MK-2206 cotreatment on apoptosis and JAK2/STAT5 and PI3K/AKT signaling in MDA-MB-231 breast cancer cells. Additionally, this work aimed to decrease the side effects of ruxolitinib and increase its anticancer effects with MK-2206 cotreatment.

METHODS AND RESULTS

Cell viability was reduced in a dose- and time-dependent manner after exposure to ruxolitinib, MK-2206 or both for 48 h, as shown by MTT assay. Ruxolitinib had a synergistic antiproliferative effect, as demonstrated by colony formation and wound healing assays. The effects of ruxolitinib, MK-2206 and their combination on apoptosis, as well as PI3K/AKT and JAK/STAT signaling, were examined by western blot analyses. Cotreatment with ruxolitinib and MK-2206 reduced proliferation with the dual inhibition of JAK2/STAT5 and PI3K/AKT signaling by decreasing PI3K, AKT, JAK2, STAT5, Caspase-9, Caspase-7, PARP, c-Myc, and Bcl-2 and increasing P53 and PTEN protein expression.

CONCLUSIONS

Our results revealed the roles of P53 and PTEN in the regulation of apoptosis and the PI3K/AKT and JAK2/STAT5 signaling pathways. The dual inhibition of JAK2/STAT5 and PI3K/AKT may reduce metastasis by decreasing tumor cell survival.

Ectopic JAK-STAT activation enables the transition to a stem-like and multilineage state conferring AR-targeted therapy resistance

Emerging evidence indicates that various cancers can gain resistance to targeted therapies by acquiring lineage plasticity. Although various genomic and transcriptomic aberrations correlate with lineage plasticity, the molecular mechanisms enabling the acquisition of lineage plasticity have not been fully elucidated. We reveal that Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling is a crucial executor in promoting lineage plasticity-driven androgen receptor (AR)-targeted therapy resistance in prostate cancer. Importantly, ectopic JAK-STAT activation is specifically required for the resistance of stem-like subclones expressing multilineage transcriptional programs but not subclones exclusively expressing the neuroendocrine-like lineage program. Both genetic and pharmaceutical inhibition of JAK-STAT signaling resensitizes resistant tumors to AR-targeted therapy. Together, these results suggest that JAK-STAT are compelling therapeutic targets for overcoming lineage plasticity-driven AR-targeted therapy resistance.

JAK-STAT core cancer pathway: An integrative cancer interactome analysis

Through a comprehensive review and in silico analysis of reported data on STAT-linked diseases, we analysed the communication pathways and interactome of the seven STATs in major cancer categories and proposed rational targeting approaches for therapeutic intervention to disrupt critical pathways and addictions to hyperactive JAK/STAT in neoplastic states. Although all STATs follow a similar molecular activation pathway, STAT1, STAT2, STAT4 and STAT6 exert specific biological profiles associated with a more restricted pattern of activation by cytokines. STAT3 and STAT5A as well as STAT5B have pleiotropic roles in the body and can act as critical oncogenes that promote many processes involved in cancer development. STAT1, STAT3 and STAT5 also possess tumour suppressive action in certain mutational and cancer type context. Here, we demonstrated member-specific STAT activity in major cancer types. Through systems biology approaches, we found surprising roles for EGFR family members, sex steroid hormone receptor ESR1 interplay with oncogenic STAT function and proposed new drug targeting approaches of oncogenic STAT pathway addiction.

Selective in vitro cytotoxicity effect of Drimia calcarata bulb extracts against p53 mutant HT-29 and p53 wild-type Caco-2 colorectal cancer cells through STAT5B regulation

Colorectal cancer is the fourth leading cause of oncological-related deaths and the third most diagnosed malignancy, worldwide. The emergence of chemoresistance is a fundamental drawback of colorectal cancer therapies and there is an urgent need for novel plant-derived therapeutics. In this regard, other compounds are needed to improve the efficacy of treatment against colorectal cancer. Medicinal plants have been effectively used by traditional doctors for decades to treat various ailments with little to no side effects. Drimia calcarata (D. calcarata) is one of the plants used by Pedi people in South Africa to treat a plethora of ailments. However, the anticancer therapeutic use of D. calcarata is less understood. Thus, this study was aimed at evaluating the potential anticancer activities of D. calcarata extracts against human colorectal cancer cells. The phytochemical analysis and antioxidant activity were analysed using LC-MS, DPPH, and FRAP. The inhibitory effects and IC50 values of D. calcarata extracts were determined using the MTT assay. Induction of cellular apoptosis was assessed using fluorescence microscopy, the Muse® Cell Analyser, and gene expression analysis by Polymerase Chain Reaction (PCR). Water extract (WE) demonstrated high phenolic, tannin, and flavonoid contents than the methanol extract (ME). LC-MS data demonstrated strong differences between the ME and WE. Moreover, WE showed the best antioxidant activity than ME. The MTT data showed that both ME and WE had no significant activity against human embryonic kidney Hek 293 cell line that served as non-cancer control cells. Caco-2 cells demonstrated high sensitivity to the ME and demonstrated resistance toward the WE, while HT-29 cells exhibited sensitivity to both D. calcarata extracts. The expression of apoptosis regulatory genes assessed by PCR revealed an upregulation of p53 by ME, accompanied by downregulation of Bcl-2 and high expression of Bax after treatment with curcumin. The Bax gene was undetected in HT-29 cells. The methanol extract induced mitochondrial-mediated apoptosis in colorectal Caco-2 and HT-29 cells and WE induced the extrinsic apoptotic pathway in HT-29 cells. ME downregulated STAT1, 3, and 5B in HT-29 cells. The D. calcarata bulb extracts, therefore, contain potential anticancer agents that can be further targeted for cancer therapeutics.

Functional Consequences of Mutations in Myeloproliferative Neoplasms

Driver mutations occur in Janus kinase 2 (JAK2), thrombopoietin receptor (MPL), and calreticulin (CALR) in BCR-ABL1 negative myeloproliferative neoplasms (MPNs). From mutations leading to one amino acid substitution in JAK2 or MPL, to frameshift mutations in CALR resulting in a protein with a different C-terminus, all the mutated proteins lead to pathologic and persistent JAK2-STAT5 activation. The most prevalent mutation, JAK2 V617F, is associated with the 3 entities polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF), while CALR and MPL mutations are associated only with ET and MF. Triple negative ET and MF patients may harbor noncanonical mutations in JAK2 or MPL. One major fundamental question is whether the conformations of JAK2 V617F, MPL W515K/L/A, or CALR mutants differ from those of their wild type counterparts so that a specific treatment could target the clone carrying the mutated driver and spare physiological hematopoiesis. Of great interest, a set of epigenetic mutations can co-exist with the phenotypic driver mutations in 35%–40% of MPNs. These epigenetic mutations, such as TET2, EZH2, ASXL1, or DNMT3A mutations, promote clonal hematopoiesis and increased fitness of aged hematopoietic stem cells in both clonal hematopoiesis of indeterminate potential (CHIP) and MPNs. Importantly, the main MPN driver mutation JAK2 V617F is also associated with CHIP. Accumulation of several epigenetic and splicing mutations favors progression of MPNs to secondary acute myeloid leukemia. Another major fundamental question is how epigenetic rewiring due to these mutations interacts with persistent JAK2-STAT5 signaling. Answers to these questions are required for better therapeutic interventions aimed at preventing progression of ET and PV to MF, and transformation of these MPNs in secondary acute myeloid leukemia.

A nontoxic dose of chrysotile can malignantly transform Met-5A cells, in which microRNA-28 has inhibitory effects

Chrysotile, which is classified as a class I carcinogen by the International Agency for Research on Cancer (IARC), has extensive application in the industry and can lead to lung or other cancers. However, whether chrysotile causes malignant mesothelioma and its molecular mechanism remain debatable. Thus, this study aimed to demonstrate the mesothelioma-inducing potential of chrysotile at the mesothelial cellular level and the function of microRNA-28 in malignantly transformed mesothelial MeT-5A cells. MeT-5A cells malignantly transformed by a nontoxic dose of chrysotile were named Asb-T, and miR-28 expression was downregulated in Asb-T cells. Restoration of miR-28 expression inhibited the proliferation, migration and invasion of Asb-T cells. We verified that IMPDH is a putative target of miR-28. The expression of IMPDH was significantly higher in Asb-T MeT-5A cells than in control cells, whereas the opposite trend was observed with miR-28 overexpression. Additionally, inhibition of IMPDH had similar effects as miR-28 overexpression. After miR-28 was elevated or IMPDH was inhibited, Ras activation was reduced, and its downstream pathways (the Erk and Akt signalling pathways) were inhibited. Surprisingly, the content of miR-28 in the blood of mesothelioma patients was higher than that in control subjects. Overall, nontoxic doses of chrysotile can cause malignant transformation of MeT-5A cells. Moreover, miR-28 inhibits the proliferation, migration and invasion of Asb-T MeT-5A cells, negatively regulates the expression of IMPDH through the Ras signalling pathway and may be an important therapeutic target.

Enhancement of myogenic differentiation and inhibition of rhabdomyosarcoma progression by miR-28-3p and miR-193a-5p regulated by SNAIL

Rhabdomyosarcoma (RMS) is a soft tissue mesenchymal tumor that affects mostly children and adolescents. It originates from the impaired myogenic differentiation of stem cells or early progenitors. SNAIL, a transcription factor that regulates epithelial-to-mesenchymal transition in tumors of epithelial origin, is also a key regulator of RMS growth, progression, and myogenic differentiation. Here, we demonstrate that the SNAIL-dependent microRNAs (miRNAs) miR-28-3p and miR-193a-5p are crucial regulators of RMS growth, differentiation, and progression. miR-28-3p and miR-193a-5p diminished proliferation and arrested RMS cells in G0/G1 phase in vitro. They induced the myogenic differentiation of both RMS cells and human myoblasts by upregulating myogenic factors. Furthermore, miR-28-3p and miR-193a-5p inhibited migration in a scratch assay, adhesion to endothelial cells, chemotaxis, and invasion toward SDF-1 and HGF and regulated angiogenic capabilities of the cells. Overexpression of miR-28-3p and miR-193a-5p induced formation of fibrotic structures and abnormal blood vessels in RMS xenografts in immunodeficient mice in vivo. Simultaneous overexpression of both miRNAs diminished tumor growth after subcutaneous implantation and inhibited the engraftment of RMS cells into bone marrow after intravenous injection in vivo. To conclude, we discovered novel SNAIL-dependent miRNAs that may become new therapeutic targets in RMS in the future.

Janus Kinases in Leukemia

Janus kinases (JAKs) transduce signals from dozens of extracellular cytokines and function as critical regulators of cell growth, differentiation, gene expression, and immune responses. Deregulation of JAK/STAT signaling is a central component in several human diseases including various types of leukemia and other malignancies and autoimmune diseases. Different types of leukemia harbor genomic aberrations in all four JAKs (JAK1, JAK2, JAK3, and TYK2), most of which are activating somatic mutations and less frequently translocations resulting in constitutively active JAK fusion proteins. JAKs have become important therapeutic targets and currently, six JAK inhibitors have been approved by the FDA for the treatment of both autoimmune diseases and hematological malignancies. However, the efficacy of the current drugs is not optimal and the full potential of JAK modulators in leukemia is yet to be harnessed. This review discusses the deregulation of JAK-STAT signaling that underlie the pathogenesis of leukemia, i.e., mutations and other mechanisms causing hyperactive cytokine signaling, as well as JAK inhibitors used in clinic and under clinical development.

Analyzing the key gene expression and prognostics values for acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is one of the first tumor types sequenced at the whole genome level. However, numbers of the mutated genes expression levels, functions, and prognostics values still unclear.

METHODS

To most ordinary mutated genes were analyzed via cancer virtual cohort discovery analysis platform (CVCDAP), and further investigated the mutational conversions, variant allele frequencies (VAF), driver genes, and potential druggable mutated genes in AML. The top mutated gene mRNA expression levels and the relationship between gene expression levels and prognosis for AML patients were performed by Gene Expression Profiling Interactive Analysis (GEPIA). Moreover, we used the UALCAN dataset to confirm the association between gene expression levels and prognosis for AML patients. Enrichment functions of the top mutated genes of AML were analyzed through Metascape. Finally, the role of these defined genes in cancer pathways and potential drug targets were analyzed by gene set cancer analysis (GSCALite).

RESULTS

The top 20 mutated genes for AML included FLT3, HPS3, ABCA6, PCLO, SLIT2, and other ones. Compared to normal control samples, NPM1 and GABRB3 were significantly downregulated in AML samples, but TP53, DNMT3A, HPS3, FLT3, SENP6, and RUNX1 were significantly overexpressed (all these genes P value <0.01). Overexpression of FLT3 and PCLO indicated a poor prognosis, but the overexpression of SLIT3 functioned as a protector for AML via GEPIA. HSP3 indicates the favorable factor for AML, but overexpression of ABCA6 (P=0.066) may act as the adverse factor by UALCAN analysis. Enrichment function analysis shows the functions of defining genes, including negative regulation of cell differentiation, small GTPase mediated signal transduction, and immune system process. Finally, these genes participate in apoptosis, cell cycle, PI3K/AKT, and RAS/MAPK signaling pathway, and FLT3 is sensitive to 5-Fluorouracil, Methotrexate, ATRA. DNMT3A and IDH2 are resistant to Trametinib. RUNX1 and TP53 were sensitive to I-BET-762 and Tubastatin A.

CONCLUSIONS

Present study showed overexpression of FLT3, ABCA6, and PCLO indicated the poor prognosis of AML, but overexpression of SLIT3 and HSP3 functioned as an AML protector. There are several drugs and small molecules that target the top 20 mutated genes in AML.

A p53-JAK-STAT connection involved in myeloproliferative neoplasm pathogenesis and progression to secondary acute myeloid leukemia

Since the discovery of JAK2 V617F as a highly prevalent somatic acquired mutation in the majority of myeloproliferative neoplasms (MPNs), it has become clear that these diseases are driven by pathologic activation of JAK2 and eventually of STAT5 and other members of the STAT family. The concept was strengthened by the discovery of the other activating driver mutations in MPL (thrombopoietin receptor, TpoR) and in calreticulin gene, which all lead to persistent activation of wild type JAK2. Although with a rare frequency, MPNs can evolve to secondary acute myeloid leukemia (sAML), a condition that is resistant to treatment. Here we focus on the role of p53 in this transition. In sAML mutations in TP53 or amplification in genes coding for negative regulators of p53 are much more frequent than in de novo AML. We review studies that explore a signaling and biochemical interaction between activated STATs and p53 in MPNs and other cancers. With the development of advanced sequencing efforts, strong evidence has been presented for dominant negative effects of mutated p53 in leukemia. In other studies, gain of function effects have been described that might be cell type specific. A more profound understanding of the potential interaction between p53 and activated STATs is necessary in order to take full advantage of novel p53-targeted therapies.

Insights regarding novel biomarkers and the pathogenesis of primary colorectal carcinoma based on bioinformatic analysis

BACKGROUND

Biomarkers are important in the study of tumor processes for early detection and precise treatment. The biomarkers that have been previously detected are not useful for clinical application for primary colorectal carcinoma (PCRC). The aim of this study was to explore clinically valuable biomarkers of PCRC based on integrated bioinformatic analysis.

MATERIAL AND METHODS

Gene expression data were acquired from the GSE41258 dataset, and the differentially expressed genes were determined between PCRC and normal colorectal samples. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were implemented via Gene Set Enrichment Analysis. A protein-protein interaction (PPI) network was constructed. The significant modules and hub genes were screened and identified in the PPI network.

RESULTS

A total of 202 DEGs were identified, including 58 upregulated and 144 downregulated genes in PCRC samples compared to those in normal colorectal samples. Enrichment analysis demonstrated that the gene sets enriched in PCRC were significantly related to bicarbonate transport, regulation of sodium ion transport, potassium ion homeostasis, regulation of telomere maintenance, and other processes. A total of 10 hub genes was identified by cytoHubba: PYY, CXCL3, CXCL11, CXCL8, CXCL12, CCL20, MMP3, P2RY14, NPY1R, and CXCL1.

CONCLUSION

The hub genes, such as NPY1R, P2RY14, and CXCL12, and the electrolyte disequilibrium resulting from the differential expression of genes, especially bicarbonate imbalance, may provide novel insights and evidence for the future diagnosis and targeted therapy of PCRC.

Twins with different personalities: STAT5B-but not STAT5A-has a key role in BCR/ABL-induced leukemia

Deregulation of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway is found in cancer with STAT5A/B controlling leukemic cell survival and disease progression. As mutations in STAT5B, but not STAT5A, have been frequently described in hematopoietic tumors, we used BCR/ABL as model systems to investigate the contribution of STAT5A or STAT5B for leukemogenesis. The absence of STAT5A decreased cell survival and colony formation. Even more drastic effects were observed in the absence of STAT5B. STAT5B-deficient cells formed BCR/ABL+ colonies or stable cell lines at low frequency. The rarely evolving Stat5b-/- cell lines expressed enhanced levels of BCR/ABL oncoprotein compared to wild-type cells. In line, Stat5b-/- leukemic cells induced leukemia with a significantly prolonged disease onset, whereas Stat5a-/- cells rapidly caused a fatal disease superimposable to wild-type cells. RNA-sequencing (RNA-seq) profiling revealed a marked enhancement of interferon (IFN)-α and IFN-γ signatures in Stat5b-/- cells. Inhibition of IFN responses rescued BCR/ABL+ colony formation of Stat5b-/--deficient cells. A downregulated IFN response was also observed in patients suffering from leukemia carrying STAT5B mutations. Our data define STAT5B as major STAT5 isoform driving BCR/ABL+ leukemia. STAT5B enables transformation by suppressing IFN-α/γ, thereby facilitating leukemogenesis. Our findings might help explain the high frequency of STAT5B mutations in hematopoietic tumors.

Akt and STAT5 mediate naïve human CD4+ T-cell early metabolic response to TCR stimulation

Metabolic pathways that regulate T-cell function show promise as therapeutic targets in diverse diseases. Here, we show that at rest cultured human effector memory and central memory CD4+ T-cells have elevated levels of glycolysis and oxidative phosphorylation (OXPHOS), in comparison to naïve T-cells. Despite having low resting metabolic rates, naive T-cells respond to TCR stimulation with robust and rapid increases in glycolysis and OXPHOS. This early metabolic switch requires Akt activity to support increased rates of glycolysis and STAT5 activity for amino acid biosynthesis and TCA cycle anaplerosis. Importantly, both STAT5 inhibition and disruption of TCA cycle anaplerosis are associated with reduced IL-2 production, demonstrating the functional importance of this early metabolic program. Our results define STAT5 as a key node in modulating the early metabolic program following activation in naive CD4+ T-cells and in turn provide greater understanding of how cellular metabolism shapes T-cell responses.

Combinatorial targeting of XPO1 and FLT3 exerts synergistic anti-leukemia effects through induction of differentiation and apoptosis in FLT3-mutated acute myeloid leukemias: from concept to clinical trial

Targeted therapies against FLT3-mutated acute myeloid leukemias have shown limited clinical efficacy primarily because of the acquisition of secondary mutations in FLT3 and persistent activation of downstream pro-survival pathways such as MEK/ERK, PI3K/AKT, and STAT5. Activation of these additional kinases may also result in phosphorylation of tumor suppressor proteins promoting their nuclear export. Thus, co-targeting nuclear export proteins (e.g., XPO1) and FLT3 concomitantly may be therapeutically effective. Here we report on the combinatorial inhibition of XPO1 using selinexor and FLT3 using sorafenib. Selinexor exerted marked cell killing of human and murine FLT3-mutant acute myeloid leukemia cells, including those harboring internal tandem duplication and/or tyrosine kinase domain point mutations. Interestingly, selinexor treatment of murine FLT3-mutant acute myeloid leukemia cells activated FLT3 and its downstream MAPK or AKT signaling pathways. When combined with sorafenib, selinexor triggered marked synergistic pro-apoptotic effects. This was preceded by elevated nuclear levels of ERK, AKT, NFκB, and FOXO3a. Five days of in vitro combination treatment using low doses (i.e., 5 to 10 nM) of each agent promoted early myeloid differentiation of MOLM13 and MOLM14 cells without noticeable cell killing. The combinatorial therapy demonstrated profound in vivo anti-leukemia efficacy in a human FLT3-mutated xenograft model. In an ongoing phase IB clinical trial the selinexor/sorafenib combination induced complete/partial remissions in six of 14 patients with refractory acute myeloid leukemia, who had received a median of three prior therapies (ClinicalTrials.gov: NCT02530476). These results provide pre-clinical and clinical evidence for an effective combinatorial treatment strategy targeting XPO1 and FLT3 in FLT3- mutated acute myeloid leukemias.

Implications of STAT3 and STAT5 signaling on gene regulation and chromatin remodeling in hematopoietic cancer

STAT3 and STAT5 proteins are oncogenic downstream mediators of the JAK–STAT pathway. Deregulated STAT3 and STAT5 signaling promotes cancer cell proliferation and survival in conjunction with other core cancer pathways. Nuclear phosphorylated STAT3 and STAT5 regulate cell-type-specific transcription profiles via binding to promoter elements and exert more complex functions involving interaction with various transcriptional coactivators or corepressors and chromatin remodeling proteins. The JAK–STAT pathway can rapidly reshape the chromatin landscape upon cytokine, hormone, or growth factor stimulation and unphosphorylated STAT proteins also appear to be functional with respect to regulating chromatin accessibility. Notably, cancer genome landscape studies have implicated mutations in various epigenetic modifiers as well as the JAK–STAT pathway as underlying causes of many cancers, particularly acute leukemia and lymphomas. However, it is incompletely understood how mutations within these pathways can interact and synergize to promote cancer. We summarize the current knowledge of oncogenic STAT3 and STAT5 functions downstream of cytokine signaling and provide details on prerequisites for DNA binding and gene transcription. We also discuss key interactions of STAT3 and STAT5 with chromatin remodeling factors such as DNA methyltransferases, histone modifiers, cofactors, corepressors, and other transcription factors.

Emerging therapeutic targets in myeloproliferative neoplasms and peripheral T-cell leukemia and lymphomas

Introduction: Hematopoietic neoplasms are often driven by gain-of-function mutations of the JAK-STAT pathway together with mutations in chromatin remodeling and DNA damage control pathways. The interconnection between the JAK-STAT pathway, epigenetic regulation or DNA damage control is still poorly understood in cancer cell biology.

Areas covered: Here, we focus on a broader description of mutational insights into myeloproliferative neoplasms and peripheral T-cell leukemia and lymphomas, since sequencing efforts have identified similar combinations of driver mutations in these diseases covering different lineages. We summarize how these pathways might be interconnected in normal or cancer cells, which have lost differentiation capacity and drive oncogene transcription.

Expert opinion: Due to similarities in driver mutations including epigenetic enzymes, JAK-STAT pathway activation and mutated checkpoint control through TP53, we hypothesize that similar therapeutic approaches could be of benefit in these diseases. We give an overview of how driver mutations in these malignancies contribute to hematopoietic cancer initiation or progression, and how these pathways can be targeted with currently available tools.

The complex roles of STAT3 and STAT5 in maintaining redox balance: Lessons from STAT-mediated xCT expression in cancer cells

STAT3 and STAT5 mediate diverse cellular processes, transcriptionally regulating gene expression and interacting with cytoplasmic proteins. Their canonical activity is stimulated by cytokines/growth factors through JAK-STAT signaling. As targets of oncogenes with intrinsic tyrosine kinase activity, STAT3 and STAT5 become constitutively active in hematologic neoplasms and solid tumors, promoting cell proliferation and survival and modulating redox homeostasis. This review summarizes reactive oxygen species (ROS)-regulated STAT activation and how STATs influence ROS production. ROS-induced effects on post-translational modifications are presented, and STAT3/5-mediated regulation of xCT, a redox-sensitive target up-regulated in numerous cancers, is discussed with regard to transcriptional cross-talk.

Epigenetic silencing of LPP/miR-28 in multiple myeloma

Aims

miR-28-5- is a tumour suppressor microRNA implicated in cancers. As a CpG island is absent in miR-28-5- but present in its host gene, LPP (LIM domain containing preferred translocation partner in lipoma), we hypothesized that miR-28-5p is epigenetically silenced by promoter DNA methylation of its host gene in multiple myeloma.

Methods

Methylation-specific PCR, verified by quantitative bisulfite pyrosequencing, was employed to study methylation of LPP/miR-28 in healthy controls (n=10), human myeloma cell lines (HMCLs) (n=15), and primary myeloma marrow samples at diagnosis (n=49) and at relapse (n=18). Quantitative reverse transcription PCR was used to investigate expression of miR-28-5p, LPP and CCND1.

Results

LPP/miR-28 was completely unmethylated in all healthy controls and 12 (80%) HMCLs, but partially methylated in three (20%) HMCLs. Methylation of LPP/miR-28 correlated with low expression of miR-285p (p=0.012) and LPP (p=0.037) in HMCLs. In RPMI-8226R cells, in which LPP/miR-28 was partially methylated, 5-AzadC treatment led to demethylation of LPP/miR-28 and re-expression of both miR-28-5p (p=0.0007) and LPP (p=0.0007), whereas continuous culture without 5-AzadC restored LPP/miR-28 methylation and reduced expression of both miR-28-5p (p=0.0013) and LPP (p=0.0025). Moreover, a known miR-28-5p target, CCND1, was expressed at higher levels in HMCLs with LPP/miR-28 methylation than those without, consistent with a tumour suppressor role of miR-28-5p in myeloma. However, in primary samples, LPP/miR-28 was methylated in two (4.1%) at diagnosis, whereas none at relapse.

Conclusions

This is the first report of epigenetic regulation of the intronic miR-28-5p expression by promoter DNA methylation of its host gene, hence warrants further study in different cancers.

O-GlcNAcylation of STAT5 controls tyrosine phosphorylation and oncogenic transcription in STAT5-dependent malignancies

The signal transducer and activator of transcription 5 (STAT5) regulates differentiation, survival, proliferation and transformation of hematopoietic cells. Upon cytokine stimulation, STAT5 tyrosine phosphorylation (pYSTAT5) is transient, while in diverse neoplastic cells persistent overexpression and enhanced pYSTAT5 are frequently found. Post-translational modifications might contribute to enhanced STAT5 activation in the context of transformation, but the strength and duration of pYSTAT5 are incompletely understood. We found that O-GlcNAcylation and tyrosine phosphorylation act together to trigger pYSTAT5 levels and oncogenic transcription in neoplastic cells. The expression of a mutated hyperactive gain-of-function (GOF) STAT5 without O-GlcNAcylation resulted in decreased tyrosine phosphorylation, oligomerization and transactivation potential and complete loss of oncogenic transformation capacity. The lack of O-GlcNAcylation diminished phospho-ERK and phospho-AKT levels. Our data show that O-GlcNAcylation of STAT5 is an important process that contributes to oncogenic transcription through enhanced STAT5 tyrosine phosphorylation and oligomerization driving myeloid transformation. O-GlcNAcylation of STAT5 could be required for nutrient sensing and metabolism of cancer cells.

Oncogenic Drivers in Myeloproliferative Neoplasms: From JAK2 to Calreticulin Mutations

During the past 10 years, major progress has been accomplished with the discovery of activating mutations that are associated with the vast majority of BCR-ABL negative human myeloproliferative neoplasms (MPNs). The identification in 2005 of JAK2 V617F triggered great interest in the JAK2-STAT5/STAT3 pathway. Discovery in 2006 of mutants of thrombopoietin receptor (TPO-R/MPL) and later on of mutants in negative regulators of JAK-STAT pathway led to the notion that persistent JAK2 activation is a hallmark of MPNs. In 2013, mutations in the gene coding for the chaperone calreticulin were reported in 20-30% of essential thrombocythemia and primary myelofibrosis patients. Here, we will address the question: what do we know about calreticulin that could help us understand its role in MPNs? In addition to oncogenic driver mutations, certain MPNs also exhibit epigenetic mutations. Targeting of both oncogenic drivers and epigenetic defects could be required for effective therapy.

Chronic Inhibition of STAT3/STAT5 in Treatment-Resistant Human Breast Cancer Cell Subtypes: Convergence on the ROS/SUMO Pathway and Its Effects on xCT Expression and System xc- Activity

Pharmacologically targeting activated STAT3 and/or STAT5 has been an active area of cancer research. The cystine/glutamate antiporter, system x_c^-, contributes to redox balance and export of intracellularly produced glutamate in response to up-regulated glutaminolysis in cancer cells. We have previously shown that blocking STAT3/5 using the small molecule inhibitor, SH-4-54, which targets the SH2 domains of both proteins, increases xCT expression, thereby increasing system x_c^- activity in human breast cancer cells. The current investigation demonstrates that chronic SH-4-54 administration, followed by clonal selection of treatment-resistant MDA-MB-231 and T47D breast cancer cells, elicits distinct subtype-dependent effects. xCT mRNA and protein levels, glutamate release, and cystine uptake are decreased relative to untreated passage-matched controls in triple-negative MDA-MB-231 cells, with the inverse occurring in estrogen-responsive T47D cells. This “ying-yang” effect is linked with a shifted balance between the phosphorylation status of STAT3 and STAT5, intracellular ROS levels, and STAT5 SUMOylation/de-SUMOylation. STAT5 emerged as a definitive negative regulator of xCT at the transcriptional level, while STAT3 activation is coupled with increased system x_c^- activity. We propose that careful classification of a patient’s breast cancer subtype is central to effectively targeting STAT3/5 as a therapeutic means of treating breast cancer, particularly given that xCT is emerging as an important biomarker of aggressive cancers.

miR-28-3p is a cellular restriction factor that inhibits human T cell leukemia virus, type 1 (HTLV-1) replication and virus infection

Human T cell leukemia virus, type 1 (HTLV-1) replication and spread are controlled by different viral and cellular factors. Although several anti-HIV cellular microRNAs have been described, such a regulation for HTLV-1 has not been reported. In this study, we found that miR-28-3p inhibits HTLV-1 virus expression and its replication by targeting a specific site within the genomic gag/pol viral mRNA. Because miR-28-3p is highly expressed in resting T cells, which are resistant to HTLV-1 infection, we investigated a potential protective role of miR-28-3p against de novo HTLV-1 infection. To this end, we developed a new sensitive and quantitative assay on the basis of the detection of products of reverse transcription. We demonstrate that miR-28-3p does not prevent virus receptor interaction or virus entry but, instead, induces a post-entry block at the reverse transcription level. In addition, we found that HTLV-1, subtype 1A isolates corresponding to the Japanese strain ATK-1 present a natural, single-nucleotide polymorphism within the miR-28-3p target site. As a result of this polymorphism, the ATK-1 virus sequence was not inhibited by miR-28. Interestingly, genetic studies on the transmission of the virus has shown that the ATK-1 strain, which carries a Thr-to-Cys transition mutation, is transmitted efficiently between spouses, suggesting that miR-28 may play an important role in HTLV-1 transmission.