Decoding Somatic Driver Gene Mutations and Affected Signaling Pathways in Human Medulloblastoma Subgroups

Linked-read based analysis of the medulloblastoma genome

Introduction

Medulloblastoma is the most common type of malignant pediatric brain tumor with group 4 medulloblastomas (G4 MBs) accounting for 40% of cases. However, the molecular mechanisms that underlie this subgroup are still poorly understood. Point mutations are detected in a large number of genes at low incidence per gene while the detection of complex structural variants in recurrently affected genes typically requires the application of long-read technologies.

Methods

Here, we applied linked-read sequencing, which combines the long-range genome information of long-read sequencing with the high base pair accuracy of short read sequencing and very low sample input requirements.

Results

We demonstrate the detection of complex structural variants and point mutations in these tumors, and, for the first time, the detection of extrachromosomal DNA (ecDNA) with linked-reads. We provide further evidence for the high heterogeneity of somatic mutations in G4 MBs and add new complex events associated with it.

Discussion

We detected several enhancer-hijacking events, an ecDNA containing the MYCN gene, and rare structural rearrangements, such a chromothripsis in a G4 medulloblastoma, chromoplexy involving 8 different chromosomes, a TERT gene rearrangement, and a PRDM6 duplication.

HIVEP3 as a potential prognostic factor promotes the development of acute myeloid leukemia

Acute myeloid leukemia (AML) is a common malignancy worldwide. Human immune deficiency virus type 1 enhancer-binding protein 3 (HIVEP3) was verified to play a vital role in types of cancers. However, the functional role of HIVEP3 in AML was rarely reported. In this study, CCK-8, colony formation assay, flow cytometry, and Trans-well chamber experiments were applied for detecting cell proliferation, apoptosis, and invasion in AML cells. The expression of proteins related to TGF-β/Smad signaling pathway was determined by western blot. Our data showed that the expression level of HIVEP3 was closely related to the risk classification and prognosis of AML patients. Moreover, HIVEP3 was highly expressed in AML patients and cells. Knockdown of HIVEP3 significantly repressed cell proliferation invasion, and enhanced cell apoptosis in HL-60 and THP-1 cells. In addition, HIVEP3 donwreglation could inhibit the TGF-β/Smad signaling pathway. TGF-β overexpression could reverse the inhibition effects of HIVEP3 knockdown on AML development and the TGF-β/Smad signaling pathway. These findings indicated that HIVEP3 contributed to the progression of AML via regulating the TGF-β/Smad signaling pathway and had a prognostic value for AML.

The non-oral infection of larval Echinococcus granulosus induces immune and metabolic reprogramming in the colon of mice

Background

The intestinal tract serves as a critical regulator for nutrient absorption and overall health. However, its involvement in anti-parasitic infection and immunity has been largely neglected, especially when a parasite is not transmitted orally. The present study investigated the colonic histopathology and functional reprogramming in mice with intraperitoneal infection of the larval Echinococcus granulosus (E. granulosus).

Results

Compared with the control group, the E. granulosus-infected mice exhibited deteriorated secreted mucus, shortened length, decreased expression of tight junction proteins zonula occludens-1 (ZO-1), and occludin in the colon. Moreover, RNA sequencing was employed to characterize colonic gene expression after infection. In total, 3,019 differentially expressed genes (1,346 upregulated and 1,673 downregulated genes) were identified in the colon of infected mice. KEGG pathway and GO enrichment analysis revealed that differentially expressed genes involved in intestinal immune responses, infectious disease-associated pathways, metabolism, or focal adhesion were significantly enriched. Among these, 18 tight junction-relative genes, 44 immune response-associated genes, and 23 metabolic genes were annotated. Furthermore, mebendazole treatment could reverse the colonic histopathology induced by E. granulosus infection.

Conclusions

Intraperitoneal infection with E. granulosus induced the pathological changes and functional reprogramming in the colon of mice, and mebendazole administration alleviated above alternations, highlighting the significance of the colon as a protective barrier against parasitic infection. The findings provide a novel perspective on host-parasite interplay and propose intestine as a possible target for treating parasitic diseases that are not transmitted orally.

Human Malignant Rhabdoid Tumor Antigens as Biomarkers and Potential Therapeutic Targets

Simple Summary

Atypical teratoid rhabdoid tumor (ATRT) is a deadly type of human pediatric brain cancer without effective treatments. ATRT is mainly linked to the inactivation of a tumor suppressor gene, SMARCB1; however, additional biomarkers remain to be identified to develop novel therapeutic strategies. Therefore, different tumor antigens and extracellular matrix modulators were investigated in two human ATRT and one kidney malignant rhabdoid tumor cell lines and compared with the nonmalignant HEK293 cell line. Alpha-fetoprotein (AFP), mucin-16 (MUC16 or cancer antigen 125/CA125), osteopontin (OPN), and mesothelin (MSLN) are highly expressed in these human malignant rhabdoid cancer cell lines. Inhibiting MMPs using a small-molecule inhibitor decreased cell survival. This biomarker discovery process may lead to the identification of novel diagnostic and therapeutic strategies, such as the development of targeted and immunotherapies against cancer biomarkers, to treat cancer patients.

Abstract

Introduction: Atypical teratoid rhabdoid tumor (ATRT) is a lethal type of malignant rhabdoid tumor in the brain, seen mostly in children under two years old. ATRT is mainly linked to the biallelic inactivation of the SMARCB1 gene. To understand the deadly characteristics of ATRT and develop novel diagnostic and immunotherapy strategies for the treatment of ATRT, this study investigated tumor antigens, such as alpha-fetoprotein (AFP), mucin-16 (MUC16/CA125), and osteopontin (OPN), and extracellular matrix modulators, such as matrix metalloproteinases (MMPs), in different human malignant rhabdoid tumor cell lines. In addition, the roles of MMPs were also examined. Materials and methods: Five human cell lines were chosen for this study, including two ATRT cell lines, CHLA-02-ATRT and CHLA-05-ATRT; a kidney malignant rhabdoid tumor cell line, G401; and two control cell lines, human embryonic kidney HEK293 and HEK293T. Both ATRT cell lines were treated with a broad-spectrum MMP inhibitor, GM6001, to investigate the effect of MMPs on cell proliferation, viability, and expression of tumor antigens and biomarkers. Gene expression was examined using a reverse transcription polymerase chain reaction (RT-PCR), and protein expression was characterized by immunocytochemistry and flow cytometry. Results: All the rhabdoid tumor cell lines tested had high gene expression levels of MUC16, OPN, AFP, and MSLN. Low expression levels of neuron-specific enolase (ENO2) by the two ATRT cell lines demonstrated their lack of neuronal genotype. Membrane-type 1 matrix metalloproteinase (MT1-MMP/MMP-14) and tissue inhibitor of metalloproteinases-2 (TIMP-2) were highly expressed in these malignant rhabdoid tumor cells, indicating their invasive phenotypes. GM6001 significantly decreased ATRT cell proliferation and the gene expression of MSLN, OPN, and several mesenchymal markers, suggesting that inhibition of MMPs may reduce the aggressiveness of rhabdoid cancer cells. Conclusion: The results obtained from this study may advance our knowledge of the molecular landscapes of human malignant rhabdoid tumors and their biomarkers for effective diagnosis and treatment. This work analyzed the expression of human malignant rhabdoid tumor antigens that may serve as biomarkers for the development of novel therapeutic strategies, such as cancer vaccines and targeted and immunotherapies targeting osteopontin and mesothelin, for the treatment of patients with ATRT and other malignant rhabdoid tumors.

The In Silico Identification of Potential Members of the Ded1/DDX3 Subfamily of DEAD-Box RNA Helicases from the Protozoan Parasite Leishmania infantum and Their Analyses in Yeast

DEAD-box RNA helicases are ubiquitous proteins found in all kingdoms of life and that are associated with all processes involving RNA. Their central roles in biology make these proteins potential targets for therapeutic or prophylactic drugs. The Ded1/DDX3 subfamily of DEAD-box proteins is of particular interest because of their important role(s) in translation. In this paper, we identified and aligned the protein sequences of 28 different DEAD-box proteins from the kinetoplast-protozoan parasite Leishmania infantum, which is the cause of the visceral form of leishmaniasis that is often lethal if left untreated, and compared them with the consensus sequence derived from DEAD-box proteins in general, and from the Ded1/DDX3 subfamily in particular, from a wide variety of other organisms. We identified three potential homologs of the Ded1/DDX3 subfamily and the equivalent proteins from the related protozoan parasite Trypanosoma brucei, which is the causative agent of sleeping sickness. We subsequently tested these proteins for their ability to complement a yeast strain deleted for the essential DED1 gene. We found that the DEAD-box proteins from Trypanosomatids are highly divergent from other eukaryotes, and consequently they are suitable targets for protein-specific drugs.

Drug Repurposing in Medulloblastoma: Challenges and Recommendations

OPINION STATEMENT

Medulloblastoma is the most frequently diagnosed primary malignant brain tumor among children. Currently available therapeutic strategies are based on surgical resection, chemotherapy, and/or radiotherapy. However, majority of patients quickly develop therapeutic resistance and are often left with long-term therapy-related side effects and sequelae. Therefore, there remains a dire need to develop more effective therapeutics to overcome the acquired resistance to currently available therapies. Unfortunately, the process of developing novel anti-neoplastic drugs from bench to bedside is highly time-consuming and very expensive. A wide range of drugs that are already in clinical use for treating non-cancerous diseases might commonly target tumor-associated signaling pathways as well and hence be of interest in treating different cancers. This is referred to as drug repurposing or repositioning. In medulloblastoma, drug repurposing has recently gained a remarkable interest as an alternative therapy to overcome therapy resistance, wherein existing non-tumor drugs are being tested for their potential anti-neoplastic effects outside the scope of their original use.

Protocadherins at the Crossroad of Signaling Pathways

Protocadherins (Pcdhs) are cell adhesion molecules that belong to the cadherin superfamily, and are subdivided into clustered (cPcdhs) and non-clustered Pcdhs (ncPcdhs) in vertebrates. In this review, we summarize their discovery, expression mechanisms, and roles in neuronal development and cancer, thereby highlighting the context-dependent nature of their actions. We furthermore provide an extensive overview of current structural knowledge, and its implications concerning extracellular interactions between cPcdhs, ncPcdhs, and classical cadherins. Next, we survey the known molecular action mechanisms of Pcdhs, emphasizing the regulatory functions of proteolytic processing and domain shedding. In addition, we outline the importance of Pcdh intracellular domains in the regulation of downstream signaling cascades, and we describe putative Pcdh interactions with intracellular molecules including components of the WAVE complex, the Wnt pathway, and apoptotic cascades. Our overview combines molecular interaction data from different contexts, such as neural development and cancer. This comprehensive approach reveals potential common Pcdh signaling hubs, and points out future directions for research. Functional studies of such key factors within the context of neural development might yield innovative insights into the molecular etiology of Pcdh-related neurodevelopmental disorders.

Characterization of epigenetic and transcriptional landscape in infantile hemangiomas with ATAC-seq and RNA-seq

Aim: This study was conducted to reveal epigenetic landscape in infantile hemangiomas (IHs) and identify transcription factors (TFs) and their downstream genes active in IHs. Materials & methods: We performed Assay for Transposase Accessible Chromatin (ATAC-seq) with RNA-seq in three pairs of IHs and their adjacent normal tissues. Functions of candidate TFs were investigated in human umbilical vein endothelial cells (HUVECs). Results: Chromatin of IH tissues is less compact. Some candidate genes and TFs were identified. In HUVECs, SPDEF inhibited cell viability and tube formation, and promoted apoptosis; SOX4 exerted the opposite effect. SPDEF may act through EPHA5, ZBTB46 and SASH1; SOX4 may act through MMP12 and HIVEP3. Conclusion: Epigenetics plays a role in IHs. SPDEF and SOX4 may act in IHs.

Molecular-Clinical Correlation in Pediatric Medulloblastoma: A Cohort Series Study of 52 Cases in Taiwan

In 2016, a project was initiated in Taiwan to adopt molecular diagnosis of childhood medulloblastoma (MB). In this study, we aimed to identify a molecular-clinical correlation and somatic mutation for exploring risk-adapted treatment, drug targets, and potential genetic predisposition. In total, 52 frozen tumor tissues of childhood MBs were collected. RNA sequencing (RNA-Seq) and DNA methylation array data were generated. Molecular subgrouping and clinical correlation analysis were performed. An adjusted Heidelberg risk stratification scheme was defined for updated clinical risk stratification. We selected 51 genes for somatic variant calling using RNA-Seq data. Relevant clinical findings were defined. Potential drug targets and genetic predispositions were explored. Four core molecular subgroups (WNT, SHH, Group 3, and Group 4) were identified. Genetic backgrounds of metastasis at diagnosis and extent of tumor resection were observed. The adjusted Heidelberg scheme showed its applicability. Potential drug targets were detected in the pathways of DNA damage response. Among the 10 patients with SHH MBs analyzed using whole exome sequencing studies, five patients exhibited potential genetic predispositions and four patients had relevant germline mutations. The findings of this study provide valuable information for updated risk adapted treatment and personalized care of childhood MBs in our cohort series and in Taiwan.

Pik3ca mutations significantly enhance the growth of SHH medulloblastoma and lead to metastatic tumour growth in a novel mouse model

Medulloblastoma (MB) is the most frequent malignant brain tumour in children with a poor outcome. Divided into four molecular subgroups, MB of the Sonic hedgehog (SHH) subgroup accounts for approximately 25% of the cases and is driven by mutations within components of the SHH pathway, such as its receptors PTCH1 or SMO. A fraction of these cases additionally harbour PIK3CA mutations, the relevance of which is so far unknown. To unravel the role of Pik3ca mutations alone or in combination with a constitutively activated SHH signalling pathway, transgenic mice were used. These mice show mutated variants within Smo, Ptch1 or Pik3ca genes in cerebellar granule neuron precursors, which represent the cellular origin of SHH MB. Our results show that Pik3ca mutations alone are insufficient to cause developmental alterations or to initiate MB. However, they significantly accelerate the growth of Shh MB, induce tumour spread throughout the cerebrospinal fluid, and result in lower survival rates of mice with a double Pik3caH1047R/SmoM2 or Pik3caH1047R/Ptch1 mutation. Therefore, PIK3CA mutations in SHH MB may represent a therapeutic target for first and second line combination treatments.

RNF213 suppresses carcinogenesis in glioblastoma by affecting MAPK/JNK signaling pathway

PURPOSE

Glioblastoma is the most common malignant brain tumor in central nervous system. Due to absence of the mechanism underlying glioblastoma, the clinical outcome is poor. RNF213 is a ring finger protein and mutation in RNF213 gene is detected in cancers. But the role of RNF213 in glioblastoma is unknown.

METHODS

RNF213 expression was detected by qPCR, western blotting, IHC technology. RNF213 was overexpressed in plasmid pcDNA3.1. Assays including CCK-8, plate colony formation, wound healing, transwell and FITC/PI dye were used to detect cell behaviors.

RESULTS

RNF213 was shown to express much lower in tumor tissues and in tumor cell lines compared to control. The patients with higher RNF213 expression displayed longer survival time. When RNF213 was overexpressed in U87MG cells, cell proliferation and colony formation were inhibited significantly. The ability of cell migration and invasion was also suppressed. FAC analysis demonstrated that cell apoptosis was increased after RNF213 overexpression. But cell cycle distribution was not affected by RNF213. Then the expression level of MEKK1, JNK, c-Jun, and cdc42 was decreased after RNF213 overexpression, but increased reversely when RNF213 was knocked down by RNAi technology.

CONCLUSIONS

RNF213 suppresses carcinogenesis and affects MAPK/JNK signaling pathway in glioblastoma. This study suggests that RNF213 might be a promising target for therapy of glioblastoma.

The ceRNA Network Has Potential Prognostic Value in Clear Cell Renal Cell Carcinoma: A Study Based on TCGA Database

Clear cell renal cell carcinoma (ccRCC) is a very common cancer in urology. Many evidences suggest that complex changed pathways take a nonnegligible part in the occurrence and development of ccRCC. Nevertheless, the underlying mechanism is not clear. In this study, the expression data between ccRCC and normal tissue samples in TCGA database were compared to distinguish differentially expressed genes (DEGs: mRNAs, miRNAs, and lncRNAs). Afterwards, we used GO enrichment and KEGG pathway enrichment analyses to explore the functions of these DEGs. We also found the correlation between three RNAs and created a competing endogenous RNA (ceRNA) network. Moreover, we used univariate Cox regression analysis to select DEGs that are connected with overall survival (OS) of ccRCC patients. We found 1652 mRNAs, 1534 lncRNAs, and 173 miRNAs that were distinguished in ccRCC compared with normal tissues. According to GO analysis, the maladjusted mRNAs are mainly concentrated in immune cell activation and kidney development, while according to KEGG, they are mainly concentrated in pathways related to cancer. A total of 5 mRNAs, 1 miRNA, and 4 lncRNAs were connected with patients' OS. In this article, a network of lncRNA-miRNA-mRNA was established; it is expected to be able to indicate possible molecular mechanisms for initial of ccRCC and provide a new viewpoint for diagnosis of ccRCC.