Characterizing invading glioma cells based on IDH1-R132H and Ki-67 immunofluorescence

CircRNA ZNF609 promotes the growth and metastasis of thyroid cancer in vivo and in vitro by downregulating miR-514a-5p

Thyroid cancer (TC) often manifests in the form of a painless cervical mass or nodule and continues to increase in incidence. Currently, much less is known about its pathogenesis in TC cells. This study sought to figure out what role the circular RNA (circRNA) ZNF609/miR-514a-5p might play in TC development and metastasis. In this study, the detection of circ-ZNF609 and miR-514a-5p expressions was carried out by qRT-PCR in TC cell lines. Cell proliferation assessment is employed by cell counting kit-8 (CCK-8) assay, colony formation, Western blot and immunofluorescence. Cell invasion and migration measurement were conducted applying wound healing and transwell. The relationship between circ-ZNF609 and miR-514a-5p was subjected to prediction with bioinformatics analysis and validated with the aid of luciferase reporter assay. Furthermore, xenograft animal experiment was adopted to confirm the role of circ-ZNF609/miR-514a-5p in TC in vivo. The data indicated that circ-ZNF609 was highly expressed, while miR-514a-5p was downregulated in TC cells. Circ-ZNF609 knockdown prevented the malignant biological behaviors of TPC-1 and IHH-4 cells. Besides, circ-ZNF609 sponged miR-514a-5p and miR-514a-5p knockdown reversed the suppressed impacts of circ-ZNF609 knockdown on TC cell malignant biological behaviors. In addition, the silence of circ-ZNF6091 significantly repressed, whereas miR-514a-5p silencing promoted TC tumorigenesis in vivo. The findings highlighted the importance of circ-ZNF609 function in facilitating TC cell development and metastasis in vitro and in vivo via binding to miR-514a-5p.

Heterozygous IDH1R132H/WT created by "single base editing" inhibits human astroglial cell growth by downregulating YAP

Mutations in the isocitrate dehydrogenase 1 (IDH1) gene have been identified in a number of cancer types, including brain cancer. The Cancer Genome Atlas project has revealed that IDH1 mutations occur in 70-80% of grade II and grade III gliomas. Until recently, most of the functional studies of IDH1 mutations in cellular models have been conducted in overexpression systems with the IDH1 wild type background. In this study, we employed a modified CRISPR/Cas9 genome editing technique called "single base editing", and efficiently introduced heterozygous IDH1 R132H mutation (IDH1^R132H/WT) in human astroglial cells. Global DNA methylation profiling revealed hypermethylation as well as hypomethylation induced by IDH1^R132H/WT. Global gene expression analysis identified molecular targets and pathways altered by IDH1^R132H/WT, including cell proliferation, extracellular matrix (ECM), and cell migration. Our phenotype analysis indicated that compared with IDH1 wild type cells, IDH1^R132H/WT promoted cell migration by upregulating integrin β4 (ITGB4); and significantly inhibited cell proliferation. Using our mutated IDH1 models generated by "single base editing", we identified novel molecular targets of IDH1^R132H/WT, namely Yes-associated protein (YAP) and its downstream signaling pathway Notch, to mediate the cell growth-inhibiting effect of IDH1^R132H/WT. In summary, the "single base editing" strategy has successfully created heterozygous IDH1 R132H mutation that recapitulates the naturally occurring IDH1 mutation. Our isogenic cellular systems that differ in a single nucleotide in one allele of the IDH1 gene provide a valuable model for novel discoveries of IDH1^R132H/WT-driven biological events.

Overcoming therapeutic resistance in glioblastoma: the way forward

Glioblastoma is the most common and lethal primary malignant brain tumor in adults. Patients die from recurrent tumors that have become resistant to therapy. New strategies are needed to design future therapies that target resistant cells. Recent genomic studies have unveiled the complexity of tumor heterogeneity in glioblastoma and provide new insights into the genomic landscape of tumor cells that survive and initiate tumor recurrence. Resistant cells also co-opt developmental pathways and display stem-like properties; hence we propose to name them recurrence-initiating stem-like cancer (RISC) cells. Genetic alterations and genomic reprogramming underlie the innate and adaptive resistance of RISC cells, and both need to be targeted to prevent glioblastoma recurrence.

IDH1 R132H Mutation Enhances Cell Migration by Activating AKT-mTOR Signaling Pathway, but Sensitizes Cells to 5-FU Treatment as NADPH and GSH Are Reduced

Aim of study

Mutations of isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) gene were recently discovered in vast majority of World Health Organization (WHO) grade II/III gliomas. This study is to understand the effects of IDH1 R132H mutation in gliomagenesis and to develop new strategies to treat glioma with IDH1 R132H mutation.

Materials and methods

Over expression of IDH1 R132H in U87MG cells was done by transfecting cells with IDH1 R132H plasmid. MTT assay, scratch repair assay and western blot were performed to study effects of IDH1 R132H mutation on cell proliferation, migration, regulating AKT-mTOR signaling pathway and cell death respectively. NADP+/NADPH and GSH quantification assays were performed to evaluate effects of IDH1 R132H mutation on the production of antioxidant NADPH and GSH.

Results

We found that over expression of IDH1 R132H mutation decreased cell proliferation consistent with previous reports; however, it increased cell migration and enhanced AKT-mTOR signaling pathway activation. Mutations in isocitrate dehydrogenase (IDH) 1 also change the function of the enzymes and cause them to produce 2-hydroxyglutarate and not produce NADPH. We tested the level of NADPH and GSH and demonstrated that IDH1 R132H mutant stable cells had significantly low NADPH and GSH level compared to control or IDH1 wild type stable cells. The reduced antioxidants (NADPH and GSH) sensitized U87MG cells with IDH R132H mutant to 5-FU treatment.

Conclusion

Our study highlights the important role of IHD1 R132H mutant in up- regulating AKT-mTOR signaling pathway and enhancing cell migration. Furthermore, we demonstrate that IDH1 R132H mutation affects cellular redox status and sensitizes gliomas cells with IDH1 R132H mutation to 5FU treatment.

Less Invasive Phenotype Found in Isocitrate Dehydrogenase-mutated Glioblastomas than in Isocitrate Dehydrogenase Wild-Type Glioblastomas: A Diffusion-Tensor Imaging Study

Purpose To explore the diffusion-tensor (DT) imaging-defined invasive phenotypes of both isocitrate dehydrogenase (IDH-1)-mutated and IDH-1 wild-type glioblastomas. Materials and Methods Seventy patients with glioblastoma were prospectively recruited and imaged preoperatively. All patients provided signed consent, and the local research ethics committee approved the study. Patients underwent surgical resection, and tumor samples underwent immunohistochemistry for IDH-1 R132H mutations. DT imaging data were coregistered to the anatomic magnetic resonance study and reconstructed to provide the anisotropic and isotropic components of the DT. The invasive phenotype was determined by using previously published criteria and correlated with IDH-1 mutation status by using the Freeman-Halton extension of the Fisher exact probability test. Results Nine patients had an IDH-1 mutation and 61 had IDH-1 wild type. All of the patients with IDH-1 mutation had a minimally invasive DT imaging phenotype. Among the IDH-1 wild-type tumors, 42 of 61 (69%) were diffusively invasive glioblastomas, 14 of 61 (23%) were locally invasive, and five of 61 (8%) were minimally invasive (P < .001). Conclusion IDH-mutated glioblastomas have a less invasive phenotype compared with IDH wild type. This finding may have implications for individualizing the extent of surgical resection and radiation therapy volumes.

Establishment of Anti-Human ATRX Monoclonal Antibody AMab-6

Gliomas are the most frequently occurring brain tumors with a heterogeneous molecular background. The molecular subgrouping of gliomas more prognostically stratifies patients into distinct groups compared with conventional histological classification. The most important molecules for the subtype diagnosis of diffuse gliomas are mutations of isocitrate dehydrogenase (IDH), TERT promoter, and α-thalassemia/mental-retardation-syndrome-X-linked (ATRX) and the codeletion of 1p/19q. Among them, IDH and ATRX mutations can be diagnosed using specific monoclonal antibodies (mAbs). We have developed many mAbs against IDH mutants, including HMab-1/HMab-2 against IDH1-R132H and multispecific mAbs MsMab-1/MsMab-2 against IDH1/2 mutations. In contrast, highly sensitive mAbs against ATRX remain to be established. In this study, we immunized mice with recombinant human ATRX and developed a novel mAb, AMab-6. The dissociation constant of AMab-6 was determined to be 9.7 × 10^-10 M, indicating that the binding affinity of AMab-6 is very high. Furthermore, AMab-6 sensitively detects ATRX in Western blot and immunohistochemical analyses, indicating that AMab-6 could become the standard marker to determine the ATRX mutation status of gliomas in immunohistochemical analyses.

Glioma Cells in the Tumor Periphery Have a Stem Cell Phenotype

Gliomas are highly infiltrative tumors incurable with surgery. Although surgery removes the bulk tumor, tumor cells in the periphery are left behind resulting in tumor relapses. The aim of the present study was to characterize the phenotype of tumor cells in the periphery focusing on tumor stemness, proliferation and chemo-resistance. This was investigated in situ in patient glioma tissue as well as in orthotopic glioblastoma xenografts. We identified 26 gliomas having the R132 mutation in Isocitrate DeHydrogenase 1 (mIDH1). A double immunofluorescence approach identifying mIDH1 positive tumor cells and a panel of markers was used. The panel comprised of six stem cell-related markers (CD133, Musashi-1, Bmi-1, Sox-2, Nestin and Glut-3), a proliferation marker (Ki-67) as well as a chemo-resistance marker (MGMT). Computer-based automated classifiers were designed to measure the mIDH1 positive nucleus area-fraction of the chosen markers. Moreover, orthotopic glioblastoma xenografts from five different patient-derived spheroid cultures were obtained and the tumor cells identified by human specific immunohistochemical markers. The results showed that tumor cells in the periphery of patient gliomas expressed stem cell markers, however for most markers at a significantly lower level than in the tumor core. The Ki-67 level was slightly reduced in the periphery, whereas the MGMT level was similar. In orthotopic glioblastoma xenografts all markers showed similar levels in the core and periphery. In conclusion tumor cells in the periphery of patient gliomas have a stem cell phenotype, although it is less pronounced than in the tumor core. Novel therapies aiming at preventing recurrence should therefore take tumor stemness into account. Migrating cells in orthotopic glioblastoma xenografts preserve expression and stem cell markers. The orthotopic model therefore has a promising translational potential.

Potential mitochondrial isocitrate dehydrogenase R140Q mutant inhibitor from traditional Chinese medicine against cancers

A recent research of cancer has indicated that the mutant of isocitrate dehydrogenase 1 and 2 (IDH1 and 2) genes will induce various cancers, including chondrosarcoma, cholangiocarcinomas, and acute myelogenous leukemia due to the effect of point mutations in the active-site arginine residues of isocitrate dehydrogenase (IDH), such as IDH1/R132, IDH2/R140, and IDH2/R172. As the inhibition for those tumor-associated mutant IDH proteins may induce differentiation of those cancer cells, these tumor-associated mutant IDH proteins can be treated as a drug target proteins for a differentiation therapy against cancers. In this study, we aim to identify the potent TCM compounds from the TCM Database@Taiwan as lead compounds of IDH2 R140Q mutant inhibitor. Comparing to the IDH2 R140Q mutant protein inhibitor, AGI-6780, the top two TCM compounds, precatorine and abrine, have higher binding affinities with target protein in docking simulation. After MD simulation, the top two TCM compounds remain as the same docking poses under dynamic conditions. In addition, precatorine is extracted from Abrus precatorius L., which represents the cytotoxic and proapoptotic effects for breast cancer and several tumor lines. Hence, we propose the TCM compounds, precatorine and abrine, as potential candidates as lead compounds for further study in drug development process with the IDH2 R140Q mutant protein against cancer.