CXCL8/CXCR2 signaling mediates bone marrow fibrosis and is a therapeutic target in myelofibrosis.

Proinflammatory signaling is a hallmark feature of human cancer, including in myeloproliferative neoplasms (MPNs), most notably myelofibrosis (MF). Dysregulated inflammatory signaling contributes to fibrotic progression in MF; however, the individual cytokine mediators elicited by malignant MPN cells to promote collagen-producing fibrosis and disease evolution are yet to be fully elucidated. Previously, we identified a critical role for combined constitutive JAK/STAT and aberrant NF-κB proinflammatory signaling in MF development. Using single-cell transcriptional and cytokine-secretion studies of primary cells from patients with MF and the human MPLW515L (hMPLW515L) murine model of MF, we extend our previous work and delineate the role of CXCL8/CXCR2 signaling in MF pathogenesis and bone marrow fibrosis progression. Hematopoietic stem/progenitor cells from patients with MF are enriched for a CXCL8/CXCR2 gene signature and display enhanced proliferation and fitness in response to an exogenous CXCL8 ligand in vitro. Genetic deletion of Cxcr2 in the hMPLW515L-adoptive transfer model abrogates fibrosis and extends overall survival, and pharmacologic inhibition of the CXCR1/2 pathway improves hematologic parameters, attenuates bone marrow fibrosis, and synergizes with JAK inhibitor therapy. Our mechanistic insights provide a rationale for therapeutic targeting of the CXCL8/CXCR2 pathway among patients with MF.

BMP2/SMAD pathway activation in JAK2/p53-mutant megakaryocyte/erythroid progenitors promotes leukemic transformation.

Leukemic transformation (LT) of myeloproliferative neoplasm (MPN) has a dismal prognosis and is largely fatal. Mutational inactivation of TP53 is the most common somatic event in LT; however, the mechanisms by which TP53 mutations promote LT remain unresolved. Using an allelic series of mouse models of Jak2/Trp53 mutant MPN, we identify that only biallelic inactivation of Trp53 results in LT (to a pure erythroleukemia [PEL]). This PEL arises from the megakaryocyte-erythroid progenitor population. Importantly, the bone morphogenetic protein 2/SMAD pathway is aberrantly activated during LT and results in abnormal self-renewal of megakaryocyte-erythroid progenitors. Finally, we identify that Jak2/Trp53 mutant PEL is characterized by recurrent copy number alterations and DNA damage. Using a synthetic lethality strategy, by targeting active DNA repair pathways, we show that this PEL is highly sensitive to combination WEE1 and poly(ADP-ribose) polymerase inhibition. These observations yield new mechanistic insights into the process of p53 mutant LT and offer new, clinically translatable therapeutic approaches.

Author Response.

How to cite this article: Krishnan A. Author Response. Indian J Crit Care Med 2023;27(12):945-946.

The Efficacy of Vision, Aphasia, Neglect Assessment in Predicting Emergent Large Vessel Occlusion in Patients Presenting with a Cerebrovascular Accident to the Emergency Department.

Background: Early identification of patients with an emergent large vessel occlusion (ELVO) ischemic stroke is crucial in the Emergency Department (ED), as they are the ideal candidates for endovascular therapy.With this study, we have attempted to use Vision, Aphasia, Neglect (VAN) screening tool in the ED for rapid identification of ELVO ischemic stroke and compared its performance with the National Institute of Health Stroke Severity (NIHSS) scale. Materials and methods: A prospective observational study was conducted in the ED of a tertiary care hospital over 18 months among all suspected stroke patients. Vision, aphasia, neglect and NIHSS scores were calculated on arrival. Magnetic resonance imaging + magnetic resonance angiography (MRI + MRA) were taken as gold standard. Results: This study found that VAN identified ELVO with 85.19% sensitivity (p-value < 0.0001), 88.64% specificity (p-value < 0.0001), and 87% diagnostic accuracy, with respect to the gold standard test. Vision, aphasia, neglect had a positive predictive value (PPV) and negative predictive value (NPV) of 82.14% and 90.7%, respectively. Time taken to perform VAN score in the ED was on average 2 minutes. National Institute of Health Stroke Severity detected ELVO with a sensitivity of 88%, specificity of 51.11%, a PPV of 53.33%, and a NPV of 88.4%. Diagnostic accuracy was 66%, and it took approximately 5 minutes to perform. When both scores were applied together for ELVO detection, NPV was 100%. Conclusion: Vision, Aphasia, Neglect score as well as NIHSS scale are both tools for clinical prediction of ELVO with VAN having a better diagnostic accuracy and utility as a screening tool in the ED. How to cite this article: Krishnan A, Srinivasarangan M, Jagadish S, Bheemanna AS, Sivasankar A. The Efficacy of Vision, Aphasia, Neglect Assessment in Predicting Emergent Large Vessel Occlusion in Patients Presenting with a Cerebrovascular Accident to the Emergency Department. Indian J Crit Care Med 2023;27(7):475-481.

Using whole genome sequence findings to assess gene-disease causality in cardiomyopathy and arrhythmia patients.

Aim: The genetic etiologies of cardiomyopathies and arrhythmias have not been fully elucidated. Materials & methods: Research findings from genome analyses in a cardiomyopathy and arrhythmia cohort were gathered. Gene-disease relationships from two databases were compared with patient phenotypes. A literature review was conducted for genes with limited evidence. Results: Of 43 genes with candidate findings from 18 cases, 23.3% of genes had never been curated, 15.0% were curated for cardiomyopathies, 16.7% for arrhythmias and 31.3% for other conditions. 25.5% of candidate findings were curated for the patient's specific phenotype with 11.8% having definitive evidence. MYH6 and TPCN1 were flagged for recuration. Conclusion: Findings from genome sequencing in disease cohorts may be useful to guide gene-curation efforts.

KDM6B protects T-ALL cells from NOTCH1-induced oncogenic stress.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematopoietic neoplasm resulting from the malignant transformation of T-cell progenitors. While activating NOTCH1 mutations are the dominant genetic drivers of T-ALL, epigenetic dysfunction plays a central role in the pathology of T-ALL and can provide alternative mechanisms to oncogenesis in lieu of or in combination with genetic mutations. The histone demethylase enzyme KDM6A (UTX) is also recurrently mutated in T-ALL patients and functions as a tumor suppressor. However, its gene paralog, KDM6B (JMJD3), is never mutated and can be significantly overexpressed, suggesting it may be necessary for sustaining the disease. Here, we used mouse and human T-ALL models to show that KDM6B is required for T-ALL development and maintenance. Using NOTCH1 gain-of-function retroviral models, mouse cells genetically deficient for Kdm6b were unable to propagate T-ALL. Inactivating KDM6B in human T-ALL patient cells by CRISPR/Cas9 showed KDM6B-targeted cells were significantly outcompeted over time. The dependence of T-ALL cells on KDM6B was proportional to the oncogenic strength of NOTCH1 mutation, with KDM6B required to prevent stress-induced apoptosis from strong NOTCH1 signaling. These studies identify a crucial role for KDM6B in sustaining NOTCH1-driven T-ALL and implicate KDM6B as a novel therapeutic target in these patients.

EPAC Regulates Melanoma Growth by Stimulating mTORC1 Signaling and Loss of EPAC Signaling Dependence Correlates with Melanoma Progression.

Exchange proteins directly activated by cAMP (EPAC) belong to a family of RAP guanine nucleotide exchange factors (RAPGEF). EPAC1/2 (RAPGEF3/4) activates RAP1 and the alternative cAMP signaling pathway. We previously showed that the differential growth response of primary and metastatic melanoma cells to cAMP is mediated by EPAC. However, the mechanisms responsible for this differential response to EPAC signaling are not understood. In this study, we show that pharmacologic inhibition or siRNA-mediated knockdown of EPAC selectively inhibits the growth and survival of primary melanoma cells by downregulation of cell-cycle proteins and inhibiting the cell-cycle progression independent of ERK1/2 phosphorylation. EPAC inhibition results in upregulation of AKT phosphorylation but a downregulation of mTORC1 activity and its downstream effectors. We also show that EPAC regulates both glycolysis and oxidative phosphorylation, and production of mitochondrial reactive oxygen species, preferentially in primary melanoma cells. Employing a series of genetically matched primary and lymph node metastatic (LNM) melanoma cells, and distant organ metastatic melanoma cells, we show that the LNM and metastatic melanoma cells become progressively less responsive and refractory to EPAC inhibition suggesting loss of dependency on EPAC signaling correlates with melanoma progression. Analysis of The Cancer Genome Atlas dataset showed that lower RAPGEF3, RAPGEF4 mRNA expression in primary tumor is a predictor of better disease-free survival of patients diagnosed with primary melanoma suggesting that EPAC signaling facilitates tumor progression and EPAC is a useful prognostic marker. These data highlight EPAC signaling as a potential target for prevention of melanoma progression. IMPLICATIONS: This study establishes loss of dependency on EPAC-mTORC1 signaling as hallmark of primary melanoma evolution and targeting this escape mechanism is a promising strategy for metastatic melanoma.

Morphological variations of the condylar head among children aged 4-15 years: A panoramic study.

BACKGROUND: Growth and development of dentocraniofacial complex occurs during various stage of development of dentition with TMJ as one of its centres of growth. The condition of temporomandibular joint can be visible from its condylar head form; therefore, it is crucial to recognize the normal morphology of condylar head during different stages of development of dentition. AIMS: The aim of the study is to view the morphological appearance of condylar head during primary dentition, mixed dentition and permenant dentition. SUBJECT AND METHODS: 400 panoramic images of 194 boys and 296 girls were collected and were divided into three groups bases on the stage of dentition. Shape of the condylar head were determined by tracing the print out of the panoramic image on an X ray viewer. RESULTS: The study showed that during primary dentition stage shape of the conylar head was dominated by round shape and as growth and development occurs the condylar head shape changes to convex. CONCLUSION: The study describes the normal morphology of mandibular condyles in a child population attending The dentition status as well as growth of craniofacial has a significant role in determining condylar morphology.

Therapeutic Efficacy of Combined JAK1/2, Pan-PIM, and CDK4/6 Inhibition in Myeloproliferative Neoplasms.

PURPOSE: The JAK1/2 inhibitor ruxolitinib has demonstrated significant benefits for patients with myeloproliferative neoplasms (MPN). However, patients often lose response to ruxolitinib or suffer disease progression despite therapy with ruxolitinib. These observations have prompted efforts to devise treatment strategies to improve therapeutic efficacy in combination with ruxolitinib therapy. Activation of JAK-STAT signaling results in dysregulation of key downstream pathways, notably increased expression of cell-cycle mediators including CDC25A and the PIM kinases. EXPERIMENTAL DESIGN: Given the involvement of cell-cycle mediators in MPNs, we sought to examine the efficacy of therapy combining ruxolitinib with a CDK4/6 inhibitor (LEE011) and a PIM kinase inhibitor (PIM447). We utilized JAK2-mutant cell lines, murine models, and primary MPN patient samples for these studies. RESULTS: Exposure of JAK2-mutant cell lines to the triple combination of ruxolitinib, LEE011, and PIM447 resulted in expected on-target pharmacodynamic effects, as well as increased apoptosis and a decrease in the proportion of cells in S-phase, compared with ruxolitinib. As compared with ruxolitinib monotherapy, combination therapy led to reductions in spleen and liver size, reduction of bone marrow reticulin fibrosis, improved overall survival, and elimination of disease-initiating capacity of treated bone marrow, in murine models of MPN. Finally, the triple combination reduced colony formation capacity of primary MPN patient samples to a greater extent than ruxolitinib. CONCLUSIONS: The triple combination of ruxolitinib, LEE011, and PIM447 represents a promising therapeutic strategy with the potential to increase therapeutic responses in patients with MPN.

JAK2S523L, a novel gain-of-function mutation in a critical autoregulatory residue in JAK2V617F- MPNs.

The SH2-JH2 linker domain of JAK2 has been implicated in the negative regulation of JAK2 activity. In 2 patients with myeloproliferative neoplasms (MPNs), we identified and characterized the novel JAK2 mutation S523L, which occurs in a key residue in the linker region. In 1 case, acquisition of JAK2S523L was associated with thrombocytosis and bone marrow megakaryocytic hyperplasia, and there were no other somatic alterations in this patient. The second patient with JAK2S523Lmutation presented with increased hematocrit and had concurrent mutations in RUNX1 and BCORL1. Consistent with the genetic and clinical data, expression of JAK2S523L causes interleukin-3-independent growth in Ba/F3 cells transduced with the erythropoietin receptor by constitutively active Jak2/Stat5 signaling.

PRMT5 Inhibition Modulates E2F1 Methylation and Gene-Regulatory Networks Leading to Therapeutic Efficacy in JAK2V617F-Mutant MPN.

We investigated the role of PRMT5 in myeloproliferative neoplasm (MPN) pathogenesis and aimed to elucidate key PRMT5 targets contributing to MPN maintenance. PRMT5 is overexpressed in primary MPN cells, and PRMT5 inhibition potently reduced MPN cell proliferation ex vivo. PRMT5 inhibition was efficacious at reversing elevated hematocrit, leukocytosis, and splenomegaly in a model of JAK2V617F+ polycythemia vera and leukocyte and platelet counts, hepatosplenomegaly, and fibrosis in the MPLW515L model of myelofibrosis. Dual targeting of JAK and PRMT5 was superior to JAK or PRMT5 inhibitor monotherapy, further decreasing elevated counts and extramedullary hematopoiesis in vivo. PRMT5 inhibition reduced expression of E2F targets and altered the methylation status of E2F1 leading to attenuated DNA damage repair, cell-cycle arrest, and increased apoptosis. Our data link PRMT5 to E2F1 regulatory function and MPN cell survival and provide a strong mechanistic rationale for clinical trials of PRMT5 inhibitors in MPN. SIGNIFICANCE: Expression of PRMT5 and E2F targets is increased in JAK2V617F+ MPN. Pharmacologic inhibition of PRMT5 alters the methylation status of E2F1 and shows efficacy in JAK2V617F/MPLW515L MPN models and primary samples. PRMT5 represents a potential novel therapeutic target for MPN, which is now being clinically evaluated.This article is highlighted in the In This Issue feature, p. 1611.

Phase 2 study of ruxolitinib and decitabine in patients with myeloproliferative neoplasm in accelerated and blast phase.

Myeloproliferative neoplasms (MPN) that have evolved into accelerated or blast phase disease (MPN-AP/BP) have poor outcomes with limited treatment options and therefore represent an urgent unmet need. We have previously demonstrated in a multicenter, phase 1 trial conducted through the Myeloproliferative Neoplasms Research Consortium that the combination of ruxolitinib and decitabine is safe and tolerable and is associated with a favorable overall survival (OS). In this phase 2 trial, 25 patients with MPN-AP/BP were treated at the recommended phase 2 dose of ruxolitinib 25 mg twice daily for the induction cycle followed by 10 mg twice daily for subsequent cycles in combination with decitabine 20 mg/m2 for 5 consecutive days in a 28-day cycle. Nineteen patients died during the study follow-up. The median OS for all patients on study was 9.5 months (95% confidence interval, 4.3-12.0). Overall response rate (complete remission + incomplete platelet recovery + partial remission) was 11/25 (44%) and response was not associated with improved survival. We conclude that the combination of decitabine and ruxolitinib was well tolerated, demonstrated favorable OS, and represents a therapeutic option for this high-risk patient population. This trial was registered at www.clinicaltrials.gov as #NCT02076191.