JAK2 V617F, MPL, and CALR Mutations in Essential Thrombocythaemia and Major Thrombotic Complications: A Single-Institute Retrospective Analysis

Decreasing circ_0014614 promotes the differentiation of bone marrow flineage cells into megakaryocytes in essential thrombocythemia via activiation of miR-138-5p/caspase3 axis

BACKGROUND

Circular RNAs (circRNA) are pivotal in hematological diseases. Previous study showed that circ_0014614 (circDAP3) was significantly underexpressed in bone marrow-derived exosomes from essential thrombocythemia (ET) patients, affecting the differentiation of bone marrow lineage cells into megakaryocytes.

METHODS

Fluorescence in situ hybridization (FISH) was used to display circ_0014614's primary cytoplasmic location in K562 cells. Cytoscape software was used to predict the circRNA-miRNA-mRNA networks, and their expression at the cellular level was detected by Quantitative reverse transcription-polymerase chain reaction (qRT-PCR). qRT-PCR was utilized to detect the expression levels of circ_0014614，miR-138-5p and caspase3 mRNA. Western blot was used to determine the protein levels of GATA-1, RUNX-1, NF-E2, CD41 and caspase3. The proliferation of K562 cells was assessed using the Cell Counting Kit-8 (CCK-8) Assay. Furthermore, the interplay between miR-138-5p and circ_0014614 or caspase3 was elucidated through a Dual-luciferase reporter assay.

RESULTS

FISH assay indicated circ_0014614's primary cytoplasmic location in K562 cells. In ET bone marrow and K562 cells, circ_0014614 and caspase3 were down-regulated, whereas miR-138-5p saw a significant surge. Overexpressing circ_0014614 curtailed K562 cells' proliferation and differentiation. Further, circ_0014614 targeted miR-138-5p, with heightened miR-138-5p levels counteracting circ_0014614's inhibition. MiR-138-5p further targeted caspase3, and caspase3 silencing neutralized suppressed miR-138-5p's effects on K562 cell differentiation.

CONCLUSION

Circ_0014614 was down-regulated in ET bone marrow and bone marrow lineage cells, and upregulating circ_0014614 can inhibit bone marrow lineage cells' proliferation and differentiation into megakaryocytes. Mechanistically, circ_0014614 functioned as ceRNA via sponging miR-138-5p and alleviated the inhibitory effect of miR-138-5p on its target caspase3, which potentially deters tumor activity in ET.

Late In-Stent Thrombosis After Carotid Artery Stenting for Symptomatic Internal Carotid Artery Stenosis in a Patient With JAK2 V617F-Positive Essential Thrombocythemia: An Illustrative Case Report

Essential thrombocythemia (ET) is a myeloproliferative disorder complicated by thrombosis in 13% of cases. The Janus kinase 2 (JAK2) V617Fmutation is present in 60% of ET cases, and it has recently been reported that the mutation itself is a significant contributor to ischemic stroke. Here, we present an illustrative case of late in-stent thrombosis following carotid artery stenting (CAS) in a patient with ET and the JAK2 V617F mutation presenting with symptomatic internal carotid artery (ICA) stenosis. An 80-year-old man with a history of JAK2 V617F-positive ET suffered from left upper motor weakness and numbness. Magnetic resonance imaging/magnetic resonance angiography revealed multiple acute cerebral infarctions scattered in the right frontal and parietal lobes and right ICA stenosis. Despite continued antiplatelet therapy, plaque size did not decrease. CAS was performed one month later; however, five months after the procedure, in-stent thrombus growth was observed, leading to severe stenosis despite administering antiplatelet or anticoagulant drugs. The thrombus was eventually resolved with increased doses of hydroxyurea and aspirin administration. In conclusion, controlling platelets and inflammation with hydroxyurea and aspirin may help improve the condition in case of rapid thrombosis due to the JAK2 V617F mutation, unlike other thromboses. This case highlights the importance of careful follow-up after CAS.

Simultaneous detection of JAK2, CALR, and MPL mutations and quantitation of JAK2 V617F allele burden in myeloproliferative neoplasms using the quenching probe-Tm method in i-densy IS-5320

INTRODUCTION

Accurate detection of myeloproliferative neoplasms (MPN)-associated gene mutations is necessary to correctly diagnose MPN. However, conventional gene testing has various limitations, including the requirement of skilled technicians, cumbersome experimental procedures, and turnaround time of several days. The gene analyzer i-densy IS-5320 allows gene testing using the quenching probe-Tm method. Specifically, pretreatment of samples including DNA extraction, amplification and detection of genes, and analysis of results are performed in a fully automatic manner after samples and test reagents are added into this system, which is compact and can be easily installed in a laboratory. The aim of this study is to investigate the sensitivity and specificity associated with the simultaneous detection of MPN-associated gene mutations.

METHODS

We conducted an analysis of MPN-associated genes using i-densy IS-5320. We analyzed 384 samples (171 JAK2 V617F mutations, 10 JAK2 exon12 mutations, 104 CALR mutations, and 26 MPL mutations) that had been examined using conventional approaches such as allele-specific polymerase chain reaction (PCR), droplet digital PCR, and the direct sequencing method.

RESULTS

The detection accuracy of JAK2 V617F, JAK2 exon 12, CALR, and MPL was 100.0% (383/383), 99.7% (383/384), 100.0% (370/370), and 99.7% (377/378), respectively. There was a strong positive correlation between the JAK2 V617F allele burden measured using conventional methods and i-densy IS-5320 (r = .989).

CONCLUSION

Overall, i-densy IS-5320 exhibited good accuracy in terms of analyzing MPN-associated genes; thus, it can serve as a replacement for conventional methods of MPN-associated gene testing.

Differential expression of circular RNAs in bone marrow-derived exosomes from essential thrombocythemia patients

Circular RNAs (circRNA) are closely associated with the pathogenesis of various hematological diseases. However, little is known about the potential functions of circRNAs in essential thrombocythemia (ET) development. The circRNA profile alterations in the bone marrow of ET patients were mainly investigated in this study. The sizes of exosomes derived from human bone marrow tissues were validated by the nanoparticle tracking analysis (NTA) method. CD63 and TSG101 expressions in exosomes were analyzed by western blot analysis. The profiles and differential expression of circRNAs in bone-derived exosomes were characterized by high-throughput sequencing. Herein, circular structures and expression of circRNAs were verified by Sanger sequencing and real-time polymerase chain reaction, respectively. The circRNA-miRNA-mRNA networks were predicted using the Cytoscape software. And we detected the effect of circ_0014614 on the transformation of K562 cells into megakaryocytes. Exosomes derived from the bone marrow of ET patients and healthy volunteers showed a diameter between 70 and 140 nm and expressed high CD63 and TSG101. Meanwhile, the circRNA profiles were significantly altered in bone marrow-derived exosomes from ET patients, among which circDAP3, circASXL1, and circRUNX1 were significantly downregulated in ET patients, thus conferring a new insight into the role of circRNAs in the pathogenesis of ET. Besides this, circRNA-encoding genes and miRNA-mRNA networks targeted by this three circRNA were involved in various biological processes and signaling pathways. And circ_0014614 could inhibit K562 cells' differentiation into megakaryocytes. The predictions of the potential function of these three differentially expressed circRNAs along with their interaction with specific miRNAs could provide a basis for circRNA-based ET diagnosis and treatment.

Correlation analysis between JAK2, MPL, and CALR mutations in patients with myeloproliferative neoplasms of Chinese Uygur and Han nationality and their clinical characteristics

Background

Genetic factors play a role in the etiology of BCR-ABL-negative myeloproliferative neoplasms (MPNs). This study explored the relationship between mutations in the Janus kinase 2 gene (JAK2), MPL, and the calreticulin gene (CALR) in Uygur and Han Chinese patients with BCR-ABL fusion gene-negative MPN and corresponding clinical features.

Methods

A total of 492 BCR-ABL-negative MPN patients treated in our hospital from May 2013 to August 2016 were enrolled. Genomic DNA was extracted from peripheral blood and used for PCR amplification and DNA sequencing. Mutations including JAK2 V617F, MPL W515L/K, and those in JAK2 exon 12 and CALR were analyzed and compared with patient clinical characteristics.

Results

Of the 492 MPN patients, 169 were Uygur and 323 were Han. In these two patient groups, JAK2 mutations were detected in 39.64% and 52.63%, respectively, CALR mutations were detected in 10.06% and 20.43%, respectively, and MPL mutations were detected in 0.93% of Han patients. The age, white blood cell count, platelet levels, and hemoglobin levels in JAK2 in Han patients were higher than those in Uygur patients.

Conclusion

Han MPN patients harboring JAK2 mutations had higher level of age, WBC, PLT, and Hb than Uyghur patients with the same mutations.

Estimation of diagnosis and prognosis in ET by assessment of CALR and JAK2V617F mutations and laboratory findings: a meta-analysis

BACKGROUND

Essential thrombocythemia (ET) is a benign disease with slow progress in which thrombosis is a cause of mortality. JAK2^V617F and calreticulin (CALR) are the most frequent mutations in this disease. In this systematic review and meta-analysis, we compared the prevalence of JAK2^V617F and CALR mutations in ET and examined the incidence of thrombosis and other hematologic indices.

METHODS

After choosing MeSH keywords, including essential thrombocythemia, JAK2^V617F, calreticulin, prognosis, and diagnosis, as well as searching Medline/PubMed and Scopus, 12 papers were selected. Data were pooled, and summary prevalence and OR were estimated using either a random-effects model or a fixed-effects model.

RESULTS

The frequency of JAK2^V617F and CALR shows heterogeneity in Caucasian population [JAK2^V617 I ²% = 84.3, P < 0.001, 95% CI 0.56 (0.51-0.61)], [CALR I ²% = 96.1, P < 0.001, 95% CI 0.23 (0.15-0.31)]. The prevalence of JAK2^V617F and CALR was 0.57 (95% CI 0.53-0.61), I ²% = 79.3 and 0.22 (95% CI 0.16-0.27), I ²% = 94, respectively. JAK2^V617F positive ET was associated with increasing odds of thrombosis [OR 2.35 (95% CI 1.83-3.02), P < 0.001]. The incidence of splenomegaly was not statistically different between these two mutations. Hemoglobin, platelet, and WBC count did not affect the risk of thrombosis.

CONCLUSIONS

Detection of CALR mutation is helpful for molecular diagnosis of ET patients as well as JAK2^V617F. Due to reduction of thrombosis in CALR-positive patients, it can be stated that such patients have less thrombotic disorders and better prognosis relative to patients bearing JAK2^V617F mutation. Therefore, detection of mutation in CALR and JAK2^V617F may contribute to diagnosis and prognosis of ET patients.

Frequency of Calreticulin (CALR) Mutation and Its Clinical Prognostic Significance in Essential Thrombocythemia and Primary Myelofibrosis: A Meta-analysis

Objective As the calreticulin (CALR) mutation frequency is significantly associated with essential thrombocythemia (ET) and primary myelofibrosis (PMF), this mutation may be an important biomarker in patients with ET and PMF. Methods We performed a literature search until April 2015 and obtained 21 relevant studies. The outcome was pooled as the effect size by using the Stata software program. Results The CALR mutation frequencies in patients with ET and PMF were 19% and 22%, respectively. The CALR mutation ratio in Asian patients with ET was 23% and higher than that in European-American patients (16%). Moreover, the mutation ratio in Asian patients with PMF was lower (21%) than that in European-American patients (23%). A slight trend toward fibrotic transformation was found in ET with CALR mutations, whereas leukemic transformation was not significant in patients with ET or PMF with CALR mutations. Conclusion CALR mutations significantly influence the incident of ET as demonstrated by the meta-analysis.

CALR mutations screening in wild type JAK2(V617F) and MPL(W515K/L) Brazilian myeloproliferative neoplasm patients

Some myeloproliferative neoplasm (MPN) patients harbor JAK2(V617F) mutation, and CALR mutations were recently discovered in wild type (WT) JAK2(V617F). We evaluated the frequency and type of CALR mutations, and clinical and hematological characteristics in WT JAK2(V617F) and MPL(W515K/L) MPN patients. Sixty-five patients were included: 21 with primary myelofibrosis (PMF), 21 with myelofibrosis post-essential thrombocythemia (MPET) and 23 with essential thrombocythemia (ET). Screening for JAK2(V617F) and MPL(W515K/L) were performed using real-time PCR, while CALR mutations were analyzed by fragment analysis and Sanger sequencing. JAK2(V617F) was the most frequent mutation (54.5%) and one patient (1.5%) harbored MPL(W515L). CALR mutations were present in 38.1% of PMF, 12.5% of ET and 33.3% of MPET patients. Five types of CALR mutations were detected, among which type 1 (32.1%) and type 2 (21.4%) were found to be the most common. A novel CALR mutation in a PMF patient was found. Patients carrying CALR mutations had higher platelet count and less presence of splenomegaly than JAK2(V617F), while triple negatives had higher C-reactive protein levels than CALR mutant carriers. Screening for CALR mutations and its correlation with clinical features could be useful for the characterization of MPN patients and result in its incorporation into a new prognostic score.