[Correlation of miR-155 Expression with Drug Sensitivity of FLT3-ITD+ Acute Myeloid Leukemia Cell Line and Its Mechanism]

OBJECTIVE

To investigate the correlation of miR-155 expression with drug sensitivity of FLT3-ITD+ acute myeloid leukemia (AML) cell line and its potential regulatory mechanism.

METHODS

By knocking out miR-155 gene in FLT3-ITD+ AML cell line MV411 through CRISPR/Cas9 gene-editing technology, monoclonal cells were screened. The genotype of these monoclonal cells was validated by PCR and Sanger sequencing. The expression of mature miRNA was measured by RT-qPCR. The treatment response of doxorubicin, quizartinib and midostaurin were measured by MTT assay and IC50 of these drugs were calculated to identify the sensitivity. Transcriptome sequencing was used to analyze change of mRNA level in MV411 cells after miR-155 knockout, gene set enrichment analysis to analyze change of signaling pathway, and Western blot to verify expressions of key molecules in signaling pathway.

RESULTS

Four heterozygotes with gene knockout and one heterozygote with gene insertion were obtained through PCR screening and Sanger sequencing. RT-qPCR results showed that the expression of mature miR-155 in the monoclonal cells was significantly lower than wild-type clones. MTT results showed that the sensitivity of MV411 cells to various anti FLT3-ITD+ AML drugs increased significantly after miR-155 knockout compared with wild-type clones. RNA sequencing showed that the mTOR signaling pathway and Wnt signaling pathway were inhibited after miR-155 knockout. Western blot showed that the expressions of key molecules p-mTOR, Wnt5α and β-catenin in signaling pathway were down-regulated.

CONCLUSION

Drug sensitivity of MV411 cells to doxorubicin, quizartinib and midostaurin can be enhanced significantly after miR-155 knockout, which is related to the inhibition of multiple signaling pathways including mTOR and Wnt signaling pathways.

Proteomic profiling of cerebrospinal fluid in pediatric myelin oligodendrocyte glycoprotein antibody-associated disease

BACKGROUND

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an autoimmune demyelinating disorder of the central nervous system.

METHODS

Extracted proteins from 34 cerebrospinal fluid (CSF) samples [patients with MOGAD (MOG group, n = 12); healthy controls (HC group, n = 12); patients with MOG seronegative and metagenomics next-generation sequencing-negative inflammatory neurological diseases (IND group, n = 10)] were processed and subjected to label-free quantitative proteomics. Supervised partial least squares-discriminant analysis (PLS-DA) and orthogonal PLS-DA (O-PLS-DA) models were also performed based on proteomics data. Functional analysis of differentially expressed proteins (DEPs) was performed using Gene Ontology, InterPro, and Kyoto Encyclopedia Genes and Genomes. An enzyme-linked immunosorbent assay was used to determine the complement levels in serum from patients with MOGAD.

RESULTS

Four hundred and twenty-nine DEPs (149 upregulated and 280 downregulated proteins) were identified in the MOG group compared to the HC group according to the P value and fold change (FC). Using the O-PLS-DA model, 872 differentially abundant proteins were identified with variable importance projection (VIP) scores > 1. Five proteins (gamma-glutamyl hydrolase, cathepsin F, interalpha-trypsin inhibitor heavy chain 5, latent transforming growth factor beta-binding protein 4 and leukocyte-associated immunoglobulin-like receptor 1) overlapping between the top 30 DEPs with top-ranked P value and FC and top 30 proteins in PLS-DA VIP lists were acquired. Functional analysis revealed that the dysregulated proteins in the MOG group were primarily involved in complement and coagulation cascades, cell adhesion, axon guidance, and glycosphingolipid biosynthesis compared to the HC group.

CONCLUSION

The proteomic alterations in CSF samples from children with MOGAD identified in the current study might provide opportunities for developing novel biomarker candidates.

Metagenomic next-generation sequencing and proteomics analysis in pediatric viral encephalitis and meningitis

Introduction

Early and accurate identification of pathogens is essential for improved outcomes in patients with viral encephalitis (VE) and/or viral meningitis (VM).

Methods

In our research, Metagenomic next-generation sequencing (mNGS) which can identify viral pathogens unbiasedly was performed on RNA and DNA to identify potential pathogens in cerebrospinal fluid (CSF) samples from 50 pediatric patients with suspected VEs and/or VMs. Then we performed proteomics analysis on the 14 HEV-positive CSF samples and another 12 CSF samples from health controls (HCs). A supervised partial least squaresdiscriminant analysis (PLS-DA) and orthogonal PLS-DA (O-PLS-DA) model was performed using proteomics data.

Results

Ten viruses in 48% patients were identified and the most common pathogen was human enterovirus (HEV) Echo18. 11 proteins overlapping between the top 20 DEPs in terms of P value and FC and the top 20 proteins in PLS-DA VIP lists were acquired.

Discussion

Our result showed mNGS has certain advantages on pathogens identification in VE and VM and our research established a foundation to identify diagnosis biomarker candidates of HEV-positive meningitis based on MS-based proteomics analysis, which could also contribute toward investigating the HEV-specific host response patterns.

[Effect of MiR-155 Knockout Mediated by Dual sgRNAs on Drug Sensitivity of FLT3-ITD+AML]

OBJECTIVE

Two sgRNAs transfected FLT3-ITD+AML cell line MV411 with different binding sites were introduced into CRISPR/cas9 to obtain MV411 cells with miR-155 gene knockout. To compare the efficiency of miR-155 gene knockout by single and double sgRNA transfection and their effects on cell phenotypes.

METHODS

The lentiviral vectors were generated containing either single sgRNA or dual sgRNAs and packaged into lentivirus particles. PCR was conducted to measure gene editing efficiency, and miR-155 expression was evaluated by qPCR. CCK-8 assay was used to evaluate the cell proliferation, and calculate drug sensitivity of cells to adriamycin and quizartinib. Annexin V-APC/7-AAD staining was used to label cell apoptosis induced by adriamycin and quizartinib.

RESULTS

In the dual sgRNAs transfected cells, a cleavage band could be observed, meaning the success of gene editing. Compared with the single sgRNA transfected MV411 cells, the expression level of mature miR-155-5p was lower in the dual sgRNA transfected cells. And, dual sgRNA transfected MV411 were more sensitive to adriamycin and quizartinib with lower IC50 and higher apoptosis rate.

CONCLUSION

The inhibition rate of miR-155 gene expression transfected by dual sgRNA is higher than that by single sgRNA. Dual sgRNA transfection can inhibit cell proliferation, reverse drug resistance, and induce apoptosis more significantly. Compared with single sgRNA transfection, dual sgRNA transfection is a highly efficient gene editing scheme.

Iron overload as a risk factor for poor graft function following allogeneic hematopoietic stem cell transplantation

Hematological malignancies are increasingly treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT). Unfortunately, iron overload is a frequent adverse effect of allo-HSCT and is associated with poor prognosis. In the present study, we investigated hematopoiesis in iron-overloaded mice and elucidated the effects of iron overload on the bone marrow (BM) microenvironment. Iron-overloaded BALB/C mice were generated by injecting 20 mg/mL saccharated iron oxide intraperitoneally. Hematoxylin-eosin staining was performed to evaluate the effects of an iron overload in mice. BM cells obtained from C57BL/6 mice were transplanted into irradiated BALB/C mice (whole-body irradiation of 4 Gy, twice with a 4-hours interval) by tail vein injection. Two weeks after allo-HSCT, the hematopoietic reconstitution capacity was evaluated in recipients by colony-forming assays. Histopathological examinations showed brown-stained granular deposits, irregularly arranged lymphocytes in the liver tissues, and blue-stained blocks in the BM collected from mice received injections of high-dose saccharated iron oxide (20 mg/mL). Iron-overloaded mice showed more platelets, higher-hemoglobin (HGB) concentration, fewer granulocyte-macrophage colony-forming units (CFU-GM), erythrocyte colony-forming units (CFU-E), and mixed granulocyte/erythrocyte/monocyte/megakaryocyte colony-forming units (CFU-mix) than healthy mice. Iron-overloaded recipients presented with reduced erythrocytes and HGB concentration in peripheral blood, along with decreased marrow stroma cells, CFU-GM, CFU-E, and CFU-mix relative to healthy recipients. Taken together, our findings demonstrate that iron overload might alter the number of red blood cells after transplantation in mice by destroying the BM microenvironment, thereby affecting the recovery of BM hematopoietic function.

[A genotyping study of 13 cases of early-onset Charcot-Marie-Tooth disease]

OBJECTIVE

To study the clinical characteristics and genetic variation of early-onset Charcot-Marie-Tooth disease (CMT).

METHODS

Children with a clinical diagnosis of early-onset CMT were selected for the study. Relevant clinical data were collected, and electromyogram and CMT-related gene detection were performed and analyzed.

RESULTS

A total of 13 cases of early-onset CMT were enrolled, including 9 males (69%) and 4 females (31%). The mean age at consultation was 4.0±2.1 years. Among them, 12 children (92%) had an age of onset less than 2 years, 9 children (69%) were diagnosed with CMT type 1 (including 6 cases of Dejerine-Sottas syndrome), 1 child (8%) with intermediate form of CMT, and 3 children (23%) with CMT type 2. The genetic test results of these 13 children showed 6 cases (46%) of PMP22 duplication mutation, 3 cases (23%) of MPZ gene insertion mutation and point mutation, 3 cases (23%) of MFN2 gene point mutation, and 1 case (8%) of NEFL gene point mutation. Eleven cases (85%) carried known pathogenic mutations and 2 cases (15%) had novel mutations. The new variant c.394C>G (p.P132A) of the MPZ gene was rated as "possibly pathogenic" and the new variant c.326A>G (p.K109R) of the MFN2 gene was rated as "pathogenic".

CONCLUSIONS

Early-onset CMT is mainly caused by PMP22 gene duplication mutation and MPZ gene mutations. The clinical phenotype is mainly CMT type 1, among which Dejerine-Sottas syndrome accounts for a considerable proportion.

[Clinical and genetic analyses of a family with atypical nonketotic hyperglycinemia caused by compound heterozygous mutations in the GLDC gene]

Nonketotic hyperglycinemia (NKH) is an autosomal recessive hereditary disease caused by a defect in the glycine cleavage system and is classified into typical and atypical NKH. Atypical NKH has complex manifestations and is difficult to diagnose in clinical practice. This article reports a family of NKH. The parents had normal phenotypes, and the older brother and the younger sister developed this disease in the neonatal period. The older brother manifested as intractable epilepsy, severe spastic diplegia, intellectual disability, an increased level of glycine in blood and cerebrospinal fluid, an increased glycine/creatinine ratio in urine, and an increased ratio of glycine concentration in cerebrospinal fluid and blood. The younger sister manifested as delayed language development, ataxia, chorea, mental and behavior disorders induced by pyrexia, hypotonia, an increased level of glycine in cerebrospinal fluid, and an increased ratio of glycine concentration in cerebrospinal fluid and blood. High-throughput sequencing found a maternal missense mutation, c.3006C>G (p.C1002W), and a paternal nonsense mutation, c.1256C>G (p.S419X), in the GLDC gene in both patients. These two mutations were thought to be pathogenic mutations by a biological software. H293T cells transfected with these two mutants of the GLDC gene had a down-regulated activity of glycine decarboxylase. NKH has various phenotypes, and high-throughput sequencing helps to make a confirmed diagnosis. Atypical NKH is associated with the downregulated activity of glycine decarboxylase caused by gene mutations.

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion associated with Mycoplasma pneumoniae infection

Background

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a clinico-radiological syndrome characterized by transient mild symptoms of encephalopathy and a reversible lesion in the splenium of the corpus callosum on magnetic resonance imaging (MRI). It is often triggered by infection. The common pathogens of MERS are viruses, especially influenza virus. However, Mycoplasma pneumoniae (M.pneumoniae) are relatively rare pathogens for MERS.

Case presentation

Here we report two paediatric cases of M.pneumoniae infection-induced MERS. The diagnosis of M.pneumoniae infection was established based on polymerase chain reaction (PCR) and specific serum antibodies (IgM). Both of the two patients presented with mild encephalopathy manifestations and recovered completely within a few days. The initial MRI showed a lesion in the central portion of the splenium of the corpus callosum, which completely resolved on the seventh and eighth day after admission for case 1 and case 2. Lumbar puncture was performed in both patients, which revealed no pleocytosis. In case 1, the patient had hyponatremia, peripheral facial nerve paralysis, and rash. To the best of our knowledge, it is the first MERS case associated with peripheral nerve damage. In case 2, interleukin-6(IL-6) was moderately increased in the cerebrospinal fluid (CSF). It suggested that IL-6 may play a role in the pathogenesis of M.pneumoniae-induced MERS.

Conclusion

Our study enriches the available information on the pathogens of MERS and provides valuable data for better understanding of this syndrome.

Low concentrations of chloroquine and 3-methyladenine suppress the viability of retinoblastoma cells synergistically with vincristine independent of autophagy inhibition

BACKGROUND

To study the inhibition of retinoblastoma cell viability by two commonly used autophagy inhibitors, chloroquine (CQ) and 3-methyladenine (3-MA), alone or in combination with the conventional chemotherapeutic drug vincristine (VCR), and to investigate whether the mechanisms of these drugs are related to inhibition of autophagy.

METHODS

On retinoblastoma cell line HXO-Rb44, VCR, CQ and 3-MA were used individually or combined. The cell viability was determined by CCK8 method, and the cellular autophagic activity was determined by Western blotting of LC3 and p62. Caspase 3 fragmentation and Akt activation was also determined by Western blotting.

RESULTS

VCR induced cell cycle arrest and apoptosis in HXO-Rb44 cells, but only inhibited autophagy at relatively high doses. Both CQ and 3-MA were synergistic with VCR to inhibit the growth of retinoblastoma cells and the combinational use significantly reduced the dosage of each drug. The lowest effective dose of CQ and 3-MA was most efficient to add on VCR; however, such dose was not sufficient to suppress autophagy in these cells. CQ could directly induce caspase activation, while 3-MA significantly inhibited Akt phosphorylation.

CONCLUSIONS

CQ and 3-MA were synergistic with VCR to inhibit retinoblastoma cells. Our result suggested a novel strategy to combine CQ or 3-MA with VCR to reduce the side effects of each drug. However, lack of change in the autophagic activity when using the two drugs at lower doses suggests multiple mechanisms of action of the same drug at different doses. At higher doses, the drugs could inhibit autophagy, while at lower doses, they suppress tumor growth via autophagy-independent mechanisms.