HMGA1 chromatin regulators induce transcriptional networks involved in GATA2 and proliferation during MPN progression

The transcription factor HMGB2 indirectly regulates APRIL expression and Gd-IgA1 production in patients with IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Proliferation-inducing ligand (APRIL) was identified as an important cause of glycosylation deficiency of IgA1 (Gd-IgA1), which can 'trigger' IgAN. Our previous study indicated that high migration group protein B2 (HMGB2) in peripheral blood mononuclear cells from patients with IgAN was associated with disease severity, but the underlying mechanism remains unclear.

MATERIALS AND METHODS

The location of HMGB2 was identified by immunofluorescence. qRT-PCR and Western blotting were used to measure HMGB2, HMGA1, and APRIL expression. Gd-IgA1 levels were detected by enzyme-linked immunosorbent assay (ELISA). In addition, we used DNA pull-down, protein profiling, and transcription factor prediction software to identify proteins bound to the promoter region of the APRIL gene. RNA interference and coimmunoprecipitation (Co-IP) were used to verify the relationships among HMGB2, high mobility group AT-hook protein 1 (HMGA1), and APRIL.

RESULTS

HMGB2 expression was greater in IgAN patients than in HCs and was positively associated with APRIL expression in B cells. DNA pull-down and protein profiling revealed that HMGB2 and HMGA1 bound to the promoter region of the APRIL gene. The expression levels of HMGA1, APRIL, and Gd-IgA1 were downregulated after HMGB2 knockdown. Co-IP indicated that HMGB2 binds to HMGA1. The Gd-IgA1 concentration in the supernatant was reduced after HMGA1 knockdown. HMGA1 binding sites were predicted in the promoter region of the APRIL gene.

CONCLUSION

HMGB2 expression is greater in IgAN patients than in healthy controls; it promotes APRIL expression by interacting with HMGA1, thereby inducing Gd-IgA1 overexpression and leading to IgAN.

Polypyrimidine tract-binding protein 3/insulin-like growth factor 2 mRNA-binding proteins 3/high-mobility group A1 axis promotes renal cancer growth and metastasis

Polypyrimidine tract-binding protein 3 (PTBP3) plays an important role in the post-transcriptional regulation of gene expression, including mRNA splicing, translation, and stability. Increasing evidence has shown that PTBP3 promotes cancer progression in several tumor types. However, the molecular mechanisms of PTBP3 in renal cell carcinoma (RCC) remain unknown. Here, tissue microarrays (TMAs) suggested that PTBP3 expression was increased in human RCC and that high PTBP3 expression was correlated with poor five-year overall survival and disease-free survival. We also showed that PTBP3 binds with HMGA1 mRNA in the 3'UTR region and let-7 miRNAs. PTBP3 interacted with IGF2BP3, and the PTBP3/IGF2BP3 axis prevented let-7 mediated HMGA1 mRNA silencing. PTBP3 promotes renal cancer cell growth and metastasis in vitro and in vivo. Taken together, our findings indicate PTBP3 serves as a regulator of HMGA1 and suggest its potential as a therapeutic agent for RCC.

HMGA1 drives chemoresistance in esophageal squamous cell carcinoma by suppressing ferroptosis

Chemotherapy is a primary treatment for esophageal squamous cell carcinoma (ESCC). Resistance to chemotherapeutic drugs is an important hurdle to effective treatment. Understanding the mechanisms underlying chemotherapy resistance in ESCC is an unmet medical need to improve the survival of ESCC. Herein, we demonstrate that ferroptosis triggered by inhibiting high mobility group AT-hook 1 (HMGA1) may provide a novel opportunity to gain an effective therapeutic strategy against chemoresistance in ESCC. HMGA1 is upregulated in ESCC and works as a key driver for cisplatin (DDP) resistance in ESCC by repressing ferroptosis. Inhibition of HMGA1 enhances the sensitivity of ESCC to ferroptosis. With a transcriptome analysis and following-up assays, we demonstrated that HMGA1 upregulates the expression of solute carrier family 7 member 11 (SLC7A11), a key transporter maintaining intracellular glutathione homeostasis and inhibiting the accumulation of malondialdehyde (MDA), thereby suppressing cell ferroptosis. HMGA1 acts as a chromatin remodeling factor promoting the binding of activating transcription factor 4 (ATF4) to the promoter of SLC7A11, and hence enhancing the transcription of SLC7A11 and maintaining the redox balance. We characterized that the enhanced chemosensitivity of ESCC is primarily attributed to the increased susceptibility of ferroptosis resulting from the depletion of HMGA1. Moreover, we utilized syngeneic allograft tumor models and genetically engineered mice of HMGA1 to induce ESCC and validated that depletion of HMGA1 promotes ferroptosis and restores the sensitivity of ESCC to DDP, and hence enhances the therapeutic efficacy. Our finding uncovers a critical role of HMGA1 in the repression of ferroptosis and thus in the establishment of DDP resistance in ESCC, highlighting HMGA1-based rewiring strategies as potential approaches to overcome ESCC chemotherapy resistance. Schematic depicting that HMGA1 maintains intracellular redox homeostasis against ferroptosis by assisting ATF4 to activate SLC7A11 transcription, resulting in ESCC resistance to chemotherapy.

Dysregulated expression of GATA2 and GATA6 transcription factors in adenomyosis: implications for impaired endometrial receptivity

OBJECTIVE

To study the effect of adenomyosis on the localized expression of the GATA binding proteins 2 and 6 (GATA2 and GATA6) zinc-finger transcription factors that are involved in proliferation of hematopoietic and endocrine cell lineages, cell differentiation, and organogenesis, potentially leading to impaired endometrial implantation.

DESIGN

Laboratory based experimental study.

SETTING

Academic hospital and laboratory.

PATIENTS

Human endometrial stromal cells (HESCs) of reproductive age patients, 18-45 years of age, with adenomyosis were compared with patients with no pathology and leiomyomatous uteri as controls (n = 4 in each group, respectively). Additionally, midsecretory phase endometrial sections were obtained from patients with adenomyosis and control patients with leiomyoma (n = 8 in each group, respectively).

INTERVENTIONS

GATA2 and GATA6 immunohistochemistry and H-SCORE were performed on the midsecretory phase endometrial sections from adenomyosis and leiomyoma control patients (n = 8 each, respectively). Control and adenomyosis patient HESC cultures were treated with placebo or 10-8 M estradiol (E2), or decidualization media (EMC) containing 10-8 M E2, 10-7 M medroxyprogesterone acetate, and 5 × 10-5 M cAMP for 6 and 10 days. Additionally, control HESC cultures (n = 4) were transfected with scrambled small interfering RNA (siRNA) (control) or GATA2-specific siRNAs for 6 days while adenomyosis HESC cultures (n = 4) were transfected with human GATA2 expression vectors to silence or induce GATA2 overexpression.

MAIN OUTCOME MEASURES

Immunohistochemistry was performed to obtain GATA2 and GATA6 H-SCORES in adenomyosis vs. control patient endometrial tissue. Expression of GATA2, GATA6, insulin-like growth factor-binding protein 1 (IGFBP1), prolactin (PRL), progesterone receptor (PGR), estrogen receptor 1 (ESR1), leukemia inhibitory factor (LIF), and Interleukin receptor 11 (IL11R) messenger RNA (mRNA) levels were analyzed using by qPCR with normalization to ACTB. Silencing and overexpression experiments also had the corresponding mRNA levels of the above factors analyzed. Western blot analysis was performed on isolated proteins from transfection experiments.

RESULTS

Immunohistochemistry revealed an overall fourfold lower GATA2 and fourfold higher GATA6 H-SCORE level in the endometrial stromal cells of patients with adenomyosis vs. controls. Decidual induction with EMC resulted in significantly lower GATA2, PGR, PRL and IGFBP1 mRNA levels in HESC cultures from patients with adenomyosis patient vs. controls. Leukemia inhibitory factor and IL11R mRNA levels were also significantly dysregulated in adenomyosis HESCs compared with controls. . Silencing of GATA2 expression in control HESCs induced an adenomyosis-like state with significant reductions in GATA2, increases in GATA6 and accompanying aberrations in PGR, PRL, ESR1 and LIF levels. Conversely, GATA2 overexpression via vector in adenomyosis HESCs caused partial restoration of the defective decidual response with significant increases in GATA2, PGR, PRL and LIF expression.

CONCLUSION

In-vivo and in-vitro experiment results demonstrate that there is an overall inverse relationship between endometrial GATA2 and GATA6 levels in patients with adenomyosis who have diminished GATA2 levels and concurrently elevated GATA6 levels. Additionally, lower GATA2 and higher GATA6 levels, together with aberrant levels of important receptors and implantation factors, such as ESR1, PGR, IGFBP1, PRL, LIF, and IL11R mRNA in HESCs from patients with adenomyosis or GATA2-silenced control HESCs, support impaired decidualization. These effects were partially restored with GATA2 overexpression in adenomyosis HESCs, demonstrating a potential therapeutic target.

Cellular carcinogenesis in preleukemic conditions:drivers and defenses

Acute myeloid leukemia (AML) arises from preleukemic conditions. We have investigated the pathogenesis of typical preleukemia, myeloproliferative neoplasms, and clonal hematopoiesis. Hematopoietic stem cells in both preleukemic conditions harbor recurrent driver mutations; additional mutation provokes further malignant transformation, leading to AML onset. Although genetic alterations are defined as the main cause of malignant transformation, non-genetic factors are also involved in disease progression. In this review, we focus on a non-histone chromatin protein, high mobility group AT-hook2 (HMGA2), and a physiological p53 inhibitor, murine double minute X (MDMX). HMGA2 is mainly overexpressed by dysregulation of microRNAs or mutations in polycomb components, and provokes expansion of preleukemic clones through stem cell signature disruption. MDMX is overexpressed by altered splicing balance in myeloid malignancies. MDMX induces leukemic transformation from preleukemia via suppression of p53 and p53-independent activation of WNT/β-catenin signaling. We also discuss how these non-genetic factors can be targeted for leukemia prevention therapy.

Method for the extraction of circulating nucleic acids based on MOF reveals cell-free RNA signatures in liver cancer

Cell-free RNA (cfRNA) allows assessment of health, status, and phenotype of a variety of human organs and is a potential biomarker to non-invasively diagnose numerous diseases. Nevertheless, there is a lack of highly efficient and bias-free cfRNA isolation technologies due to the low abundance and instability of cfRNA. Here, we developed a reproducible and high-efficiency isolation technology for different types of cell-free nucleic acids (containing cfRNA and viral RNA) in serum/plasma based on the inclusion of nucleic acids by metal-organic framework (MOF) materials, which greatly improved the isolation efficiency and was able to preserve RNA integrity compared with the most widely used research kit method. Importantly, the quality of cfRNA extracted by the MOF method is about 10-fold that of the kit method, and the MOF method isolates more than three times as many different RNA types as the kit method. The whole transcriptome mapping characteristics of cfRNA in serum from patients with liver cancer was described and a cfRNA signature with six cfRNAs was identified to diagnose liver cancer with high diagnostic efficiency (area under curve = 0.905 in the independent validation cohort) using this MOF method. Thus, this new MOF isolation technique will advance the field of liquid biopsy, with the potential to diagnose liver cancer.

m6A-mediated lncRNA NEAT1 plays an oncogenic role in non-small cell lung cancer by upregulating the HMGA1 expression through binding miR-361-3p

BACKGROUND

Lung cancer is the most common primary malignant tumor of the lung, and 85% of lung cancer is non-small cell lung cancer (NSCLC). The N6-methyladenosine (m6A) and long noncoding RNAs (lncRNAs) have been widely reported to participate in the development of non-small cell lung cancer.

OBJECTIVE

However, the potential molecular mechanisms of m6A-regulated lncRNAs in NSCLC still need further investigation.

METHODS

The expression levels and the role of lncRNA NEAT1 in NSCLC tissues or cells were measured by RT-qPCR, Western blot, cell counting kit 8 (CCK-8), flow cytometry assay. RNA immunoprecipitation (RIP) was used to measure the levels of m6A modification of NEAT1. Bioinformatics analysis and dual-luciferase reporter gene assay were detected the relationship between miR-361-3p and NEAT1/HMGA1. Mouse xenograft tumor models were established to confirm the effects of lncRNA NEAT1 in vivo.

RESULTS

In this study, we verified whether m6A-modified lncRNA nuclear enriched abundant transcript 1 (NEAT1) is involved in NSCLC progression via miR-361-3p/HMGA1 axis. Firstly, we found that lncRNA NEAT1 was upregulated in NSCLC, and was associated with a poor survival in NSCLC patients. Methyltransferase like 3 (METTL3)-mediated m6A modification stabilized and upregulated NEAT1 expression. Next, function experiment indicated that depletion of METTL3 and NEAT1 induced cell apoptosis and inhibited cell proliferation, epithelial-mesenchymal transition (EMT). Likewise, in vivo experiments further supported the oncogenic role of NEAT1 in NSCLC. In addition, the molecular mechanism was uncovered in our study, and we found that lncRNA NEAT1 promoted the expression of high-mobility group AT-hook 1 (HMGA1) by sponging miR-361-3p and then promoted tumorigenesis of NSCLC.

CONCLUSION

In conclusion, our findings demonstrated that METTL3-mediated m6A modification accelerated NSCLC progression by regulating the NEAT1/miR-361-3p/HMGA1 axis, which provides important targets for the treatment of NSCLC.

Inflammation and bone marrow fibrosis: novel immunotherapeutic targets

PURPOSE OF REVIEW

Myelofibrosis (MF) is primarily driven by constitutive activation of the Janus kinase/signal transducer of activators of transcription (JAK/STAT) pathway. While JAK inhibitors have shown to alleviate disease symptoms, their disease-modifying effects in MF are limited. The only curative treatment remains allogeneic stem cell transplantation, which can be applied to a minority of patients. As a result, there is a need to explore novel targets in MF to facilitate appropriate drug development and therapeutic pathways.

RECENT FINDINGS

Recent research has focused on identifying novel signals that contribute to the abnormal cross-talk between hematopoietic and stromal cells, which promotes MF and disease progression. Inflammation and immune dysregulation have emerged as key drivers of both the initiation and progression of MF. A growing number of actionable targets has been identified, including cytokines, transcription factors, signalling networks and cell surface-associated molecules. These targets exhibit dysfunctions in malignant and nonmalignant hematopoietic cells, but also in nonhematopoietic cells of the bone marrow. The study of these inflammation-related molecules, in preclinical models and MF patient's samples, is providing novel therapeutic targets.

SUMMARY

The identification of immunotherapeutic targets is expanding the therapeutic landscape of MF. This review provides a summary of the most recent advancements in the study of immunotherapeutic targets in MF.

Epigenetics in myeloproliferative neoplasms

The myeloproliferative neoplasms (MPNs) are a group of acquired clonal disorders where mutations drive proliferative disease resulting in increased blood counts and in some cases end-stage myelofibrosis. Epigenetic changes are the reversible modifications to DNA- and RNA-associated proteins that impact gene activity without changing the DNA sequence. This review summarizes mechanisms of epigenetic changes and the nucleosome. The drivers and epigenetic regulators in MPNs are outlined. In MPNs, distinct patterns of epigenetic dysregulation have been seen in chronic and in advanced phases. Methylation age and histone modification are altered in MPNs and by further treatment. The alterations found in methylation age in MPNs and with treatment are discussed, and the changes in histone modification with Janus kinase (JAK) inhibition are evaluated. Currently available therapeutic areas where the epigenome can be altered are outlined. Thus, we review the current knowledge and understanding of epigenetics in MPN and consider further management options. Understanding the epigenome and its alteration in MPNs and epigenetic changes associated with the progression of disease will lead to advances in therapeutic options.

High expression of miR-107 and miR-17 predicts poor prognosis and guides treatment selection in acute myeloid leukemia

Background

The prognostic significance of miR-107 and miR-17 in patients with acute myeloid leukemia (AML) remains unclear.

Methods

A total of 173 patients with de novo AML from the Cancer Genome Atlas database were enrolled in this study and further divided into a chemotherapy group (98 cases) and an allogeneic hematopoietic stem cell transplantation (allo-HSCT) group (75 cases) according to their therapy regimen.

Results

In the chemotherapy cohort, high miR-107 or miR-17 expression was associated with poorer overall survival (OS) and event-free survival (EFS). On the other hand, there were no significant differences in OS and EFS between the high- and low-expression subgroups in the allo-HSCT group. Next, we stratified the total number of patients with AML into high- and low-expression groups according to the median expression levels of miR-107 or miR-17. In the high miR-107 or miR-17 expression group, patients treated with allo-HSCT had longer OS than those treated with chemotherapy. In the low miR-107 or miR-17 expression group, no significant differences in OS and EFS were observed between the two therapy subgroups. When patients were further clustered into three groups (both low miR-107 and low miR-17, either high miR-107 or high miR-17, and both high miR-107 and high miR-17), patients with both high miR-107 and high miR-17 expression had the worst OS and EFS of the entire group and of the chemotherapy group. On the other hand, there were no significant differences in OS and EFS among the three subgroups in the allo-HSCT group. Cox regression confirmed the concurrence of high expression of miR-107 and miR-17 might act as an independent prognostic factor for EFS and OS in the entire group and the chemotherapy group. Bioinformatics analysis showed differentially expressed genes (DEGs) associated with miR-107 and miR-17 expression were mainly enriched in multiple metabolic processes.

Conclusions

The combination of miR-107 and miR-17 provides prognostic significance for patients with AML and should be considered in the clinical selection of the optimal treatment regimen when deciding between chemotherapy and allo-HSCT.

Genetic basis and molecular profiling in myeloproliferative neoplasms

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are clonal diseases originating from a single hematopoietic stem cell that cause excessive production of mature blood cells. The 3 subtypes, that is, polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are diagnosed according to the World Health Organization (WHO) and international consensus classification (ICC) criteria. Acquired gain-of-function mutations in 1 of 3 disease driver genes (JAK2, CALR, and MPL) are the causative events that can alone initiate and promote MPN disease without requiring additional cooperating mutations. JAK2-p.V617F is present in >95% of PV patients, and also in about half of the patients with ET or PMF. ET and PMF are also caused by mutations in CALR or MPL. In ∼10% of MPN patients, those referred to as being "triple negative," none of the known driver gene mutations can be detected. The common theme between the 3 driver gene mutations and triple-negative MPN is that the Janus kinase-signal transducer and activator of transcription (JAK/STAT) signaling pathway is constitutively activated. We review the recent advances in our understanding of the early events after the acquisition of a driver gene mutation. The limiting factor that determines the frequency at which MPN disease develops with a long latency is not the acquisition of driver gene mutations, but rather the expansion of the clone. Factors that control the conversion from clonal hematopoiesis to MPN disease include inherited predisposition, presence of additional mutations, and inflammation. The full extent of knowledge of the mutational landscape in individual MPN patients is now increasingly being used to predict outcome and chose the optimal therapy.

JAK2 V617F allele burden in polycythemia vera: burden of proof

Polycythemia vera (PV) is a hematopoietic stem cell neoplasm defined by activating somatic mutations in the JAK2 gene and characterized clinically by overproduction of red blood cells, platelets, and neutrophils; a significant burden of disease-specific symptoms; high rates of vascular events; and evolution to a myelofibrosis phase or acute leukemia. The JAK2V617F variant allele frequency (VAF) is a key determinant of outcomes in PV, including thrombosis and myelofibrotic progression. Here, we critically review the dynamic role of JAK2V617F mutation burden in the pathogenesis and natural history of PV, the suitability of JAK2V617F VAF as a diagnostic and prognostic biomarker, and the utility of JAK2V617F VAF reduction in PV treatment.

Pathogenic human variant that dislocates GATA2 zinc fingers disrupts hematopoietic gene expression and signaling networks

Although certain human genetic variants are conspicuously loss of function, decoding the impact of many variants is challenging. Previously, we described a patient with leukemia predisposition syndrome (GATA2 deficiency) with a germline GATA2 variant that inserts 9 amino acids between the 2 zinc fingers (9aa-Ins). Here, we conducted mechanistic analyses using genomic technologies and a genetic rescue system with Gata2 enhancer-mutant hematopoietic progenitor cells to compare how GATA2 and 9aa-Ins function genome-wide. Despite nuclear localization, 9aa-Ins was severely defective in occupying and remodeling chromatin and regulating transcription. Variation of the inter-zinc finger spacer length revealed that insertions were more deleterious to activation than repression. GATA2 deficiency generated a lineage-diverting gene expression program and a hematopoiesis-disrupting signaling network in progenitors with reduced granulocyte-macrophage colony-stimulating factor (GM-CSF) and elevated IL-6 signaling. As insufficient GM-CSF signaling caused pulmonary alveolar proteinosis and excessive IL-6 signaling promoted bone marrow failure and GATA2 deficiency patient phenotypes, these results provide insight into mechanisms underlying GATA2-linked pathologies.

Establishing a prognostic model of chromatin modulators and identifying potential drug candidates in renal clear cell patients

BACKGROUND

Renal carcinoma is a common malignant tumor of the urinary system. Advanced renal carcinoma has a low 5-year survival rate and a poor prognosis. More and more studies have confirmed that chromatin regulators (CRs) can regulate the occurrence and development of cancer. This article investigates the functional and prognostic value of CRs in renal carcinoma patients.

METHODS

mRNA expression and clinical information were obtained from The Cancer Genome Atlas database. Univariate Cox regression analysis and LASSO regression analysis were used to select prognostic chromatin-regulated genes and use them to construct a risk model for predicting the prognosis of renal cancer. Differences in prognosis between high-risk and low-risk groups were compared using Kaplan-Meier analysis. In addition, we analyzed the relationship between chromatin regulators and tumor immune infiltration, and explored differences in drug sensitivity between risk groups.

RESULTS

We constructed a model consisting of 11 CRs to predict the prognosis of renal cancer patients. We not only successfully validated its feasibility, but also found that the 11 CR-based model was an independent prognostic factor. Functional analysis showed that CRs were mainly enriched in cancer development-related signalling pathways. We also found through the TIMER database that CR-based models were also associated with immune cell infiltration and immune checkpoints. At the same time, the genomics of drug sensitivity in cancer database was used to analyze the commonly used drugs of renal clear cell carcinoma patients. It was found that patients in the low-risk group were sensitive to medicines such as axitinib, pazopanib, sorafenib, and gemcitabine. In contrast, those in the high-risk group may be sensitive to sunitinib.

CONCLUSION

The chromatin regulator-related prognostic model we constructed can be used to assess the prognostic risk of patients with clear cell renal cell carcinoma. The results of this study can bring new ideas for targeted therapy of clear cell renal carcinoma, helping doctors to take corresponding measures in advance for patients with different risks.

HMGA1 induces FGF19 to drive pancreatic carcinogenesis and stroma formation

High mobility group A1 (HMGA1) chromatin regulators are upregulated in diverse tumors where they portend adverse outcomes, although how they function in cancer remains unclear. Pancreatic ductal adenocarcinomas (PDACs) are highly lethal tumors characterized by dense desmoplastic stroma composed predominantly of cancer-associated fibroblasts and fibrotic tissue. Here, we uncover an epigenetic program whereby HMGA1 upregulates FGF19 during tumor progression and stroma formation. HMGA1 deficiency disrupts oncogenic properties in vitro while impairing tumor inception and progression in KPC mice and subcutaneous or orthotopic models of PDAC. RNA sequencing revealed HMGA1 transcriptional networks governing proliferation and tumor-stroma interactions, including the FGF19 gene. HMGA1 directly induces FGF19 expression and increases its protein secretion by recruiting active histone marks (H3K4me3, H3K27Ac). Surprisingly, disrupting FGF19 via gene silencing or the FGFR4 inhibitor BLU9931 recapitulates most phenotypes observed with HMGA1 deficiency, decreasing tumor growth and formation of a desmoplastic stroma in mouse models of PDAC. In human PDAC, overexpression of HMGA1 and FGF19 defines a subset of tumors with extremely poor outcomes. Our results reveal what we believe is a new paradigm whereby HMGA1 and FGF19 drive tumor progression and stroma formation, thus illuminating FGF19 as a rational therapeutic target for a molecularly defined PDAC subtype.

Preclinical studies on the use of a P-selectin-blocking monoclonal antibody to halt progression of myelofibrosis in the Gata1low mouse model

The bone marrow (BM) and spleen from patients with myelofibrosis (MF), as well as those from the Gata1low mouse model of the disease contain increased number of abnormal megakaryocytes. These cells express high levels of the adhesion receptor P-selectin on their surface, which triggers a pathologic neutrophil emperipolesis, leading to increased bioavailability of transforming growth factor-β (TGF-β) in the microenvironment and disease progression. With age, Gata1low mice develop a phenotype similar to that of patients with MF, which is the most severe of the Philadelphia-negative myeloproliferative neoplasms. We previously demonstrated that Gata1low mice lacking the P-selectin gene do not develop MF. In the current study, we tested the hypothesis that pharmacologic inhibition of P-selectin may normalize the phenotype of Gata1low mice that have already developed MF. To test this hypothesis, we have investigated the phenotype expressed by aged Gata1low mice treated with the antimouse monoclonal antibody RB40.34, alone and also in combination with ruxolitinib. The results indicated that RB40.34 in combination with ruxolitinib normalizes the phenotype of Gata1low mice with limited toxicity by reducing fibrosis and the content of TGF-β and CXCL1 (two drivers of fibrosis in this model) in the BM and spleen and by restoring hematopoiesis in the BM and the architecture of the spleen. In conclusion, we provide preclinical evidence that treatment with an antibody against P-selectin in combination with ruxolitinib may be more effective than ruxolitinib alone to treat MF in patients.

Molecular Pathogenesis of Myeloproliferative Neoplasms: From Molecular Landscape to Therapeutic Implications

Despite distinct clinical entities, the myeloproliferative neoplasms (MPN) share morphological similarities, propensity to thrombotic events and leukemic evolution, and a complex molecular pathogenesis. Well-known driver mutations, JAK2, MPL and CALR, determining constitutive activation of JAK-STAT signaling pathway are the hallmark of MPN pathogenesis. Recent data in MPN patients identified the presence of co-occurrence somatic mutations associated with epigenetic regulation, messenger RNA splicing, transcriptional mechanism, signal transduction, and DNA repair mechanism. The integration of genetic information within clinical setting is already improving patient management in terms of disease monitoring and prognostic information on disease progression. Even the current therapeutic approaches are limited in disease-modifying activity, the expanding insight into the genetic basis of MPN poses novel candidates for targeted therapeutic approaches. This review aims to explore the molecular landscape of MPN, providing a comprehensive overview of the role of drive mutations and additional mutations, their impact on pathogenesis as well as their prognostic value, and how they may have future implications in therapeutic management.