Cancer: Keeping it real to kill glioblastoma

The pivotal role of autophagy in the pathogenesis and therapy of medulloblastoma

Medulloblastoma (MB) is the most frequent malignant brain tumor in children. MB originates from neural precursor cells in distinctive regions of the rhombic lip and their maturation occurs in the cerebellum or the brain stem during embryonal development. Autophagy is also referred to as self-eating' which is a catabolic process that often triggers cellular homeostasis through the salvaging of degenerated proteins as well as organelles. Autophagy influence cell survival via aberrant proteins that could accumulate within the cell and influence potential signaling and transport mechanisms. The role of autophagy in MB aggressiveness as well as tumorigenesis is a very complex process. This review targets specifically data reporting the key roles of autophagy in the pathogenesis and therapy of MB.

Total Synthesis of the Proposed Structure of Neaumycin B

The total synthesis of the proposed structure of anti-glioblastoma natural product neaumycin B was achieved in 22 steps (longest linear sequence). The synthesis features HCl-mediated [6,6]-spiroketalization, a combination of Krische iridium-catalyzed crotylation, Marshall palladium-catalyzed propargylation, Fürstner nickel-catalyzed regio- and enantioselective vicinal monoprotected diol formation, Brown crotylation and asymmetric halide-aldehyde cycloaddition, so as to establish the challenging contiguous stereocenters.

Focal structural variants revealed by whole genome sequencing disrupt the histone demethylase KDM4C in B-cell lymphomas

Histone methylation-modifiers, such as EZH2 and KMT2D, are recurrently altered in B-cell lymphomas. To comprehensively describe the landscape of alterations affecting genes encoding histone methylation-modifiers in lymphomagenesis we investigated whole genome and transcriptome data of 186 mature B-cell lymphomas sequenced in the ICGC MMML-Seq project. Besides confirming common alterations of KMT2D (47% of cases), EZH2 (17%), SETD1B (5%), PRDM9 (4%), KMT2C (4%), and SETD2 (4%), also identified by prior exome or RNA-sequencing studies, we here found recurrent alterations to KDM4C in chromosome 9p24, encoding a histone demethylase. Focal structural variation was the main mechanism of KDM4C alterations, and was independent from 9p24 amplification. We also identified KDM4C alterations in lymphoma cell lines including a focal homozygous deletion in a classical Hodgkin lymphoma cell line. By integrating RNA-sequencing and genome sequencing data we predict that KDM4C structural variants result in loss-offunction. By functional reconstitution studies in cell lines, we provide evidence that KDM4C can act as a tumor suppressor. Thus, we show that identification of structural variants in whole genome sequencing data adds to the comprehensive description of the mutational landscape of lymphomas and, moreover, establish KDM4C as a putative tumor suppressive gene recurrently altered in subsets of B-cell derived lymphomas.

Discovery of a new class of JMJD6 inhibitors and structure-activity relationship study

JmjC domain-containing protein 6 (JMJD6) has been thought as a potential target for various diseases particularly cancer. However, few selective JMJD6 inhibitors have been reported. In this investigation, molecular docking and biological activity evaluation were performed to retrieve new JMJD6 inhibitors, which led to the identification of a hit compound, J2. Further structural optimization and structure-activity relationship (SAR) analysis towards J2 were carried out, which gave a new potent JMJD6 inhibitor, 7p. This compound showed an IC₅₀ value of 0.681 μM against JMJD6, but displayed no activity against other tested JmjC domain-containing protein family members, indicating good selectivity (>100 fold). Collectively, this investigation offers a selective JMJD6 inhibitor, which could be taken as a lead compound for subsequent drug discovery targeting JMJD6.

Targeting MYCN in Molecularly Defined Malignant Brain Tumors

Misregulation of MYC genes, causing MYC overexpression or protein stabilization, is frequently found in malignant brain tumors highlighting their important roles as oncogenes. Brain tumors in children are the most lethal of all pediatric malignancies and the most common malignant primary adult brain tumor, glioblastoma, is still practically incurable. MYCN is one of three MYC family members and is crucial for normal brain development. It is associated with poor prognosis in many malignant pediatric brain tumor types and is focally amplified in specific adult brain tumors. Targeting MYCN has proved to be challenging due to its undruggable nature as a transcription factor and for its importance in regulating developmental programs also in healthy cells. In this review, we will discuss efforts made to circumvent the difficulty of targeting MYCN specifically by using direct or indirect measures to treat MYCN-driven brain tumors. We will further consider the mechanism of action of these measures and suggest which molecularly defined brain tumor patients that might benefit from MYCN-directed precision therapies.

Jumonji domain-containing protein 6 protein and its role in cancer

The jumonji domain‐containing protein 6 (JMJD6) is a Fe(II)‐ and 2‐oxoglutarate (2OG)‐dependent oxygenase that catalyses lysine hydroxylation and arginine demethylation of histone and non‐histone peptides. Recently, the intrinsic tyrosine kinase activity of JMJD6 has also been reported. The JMJD6 has been implicated in embryonic development, cellular proliferation and migration, self‐tolerance induction in the thymus, and adipocyte differentiation. Not surprisingly, abnormal expression of JMJD6 may contribute to the development of many diseases, such as neuropathic pain, foot‐and‐mouth disease, gestational diabetes mellitus, hepatitis C and various types of cancer. In the present review, we summarized the structure and functions of JMJD6, with particular emphasis on the role of JMJD6 in cancer progression.

Microarray expression profiles and bioinformatics analysis of mRNAs, lncRNAs, and circRNAs in the secondary temozolomide-resistant glioblastoma

Temozolomide is a first line anti-tumor drug used for the treatment of patients with Glioblastoma multiforme (GBM). However, the drug resistance to temozolomide limits its clinical application. Therefore, novel strategies to overcome chemoresistance are desperately needed for improved treatment of human GBM. Here, we simultaneously detected, for the first time, the expression profiles of mRNAs, lncRNAs, and circRNAs in three pairs of secondary temozolomide-resistant glioblastoma (STRG) and matched primary glioblastoma tissues by microarrays. Using these data, we discovered a total of 92 mRNA, 299 lncRNAs and 53 circRNAs were altered in human glioma tissue after chemotherapy with temozolomide. The functions of differentially expressed lncRNAs, circRNAs were annotated by analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The results showed that the highest enriched GO terms of the upregulated lncRNAs were embryonic forelimb morphogenesis (BP), extracellular space (CC), and serine-type endopeptidase activity (MF). Meanwhile, GO:0035360(BP), PRC1 complex (CC), and ubiquitin-protein transferase activity (MF) were the highest enriched GO terms targeted by downregulated lncRNAs. The NF-kappa B signaling pathway were significantly enriched in the STRG. However, circRNAs highest enriched GO term was viral process, chromosome, and protein transporter activity, respectively. KEGG pathway analysis showed that circRNAs in the network were enriched in ErbB signaling pathway. Furthermore, we also predicted the potential role of these differentially expressed ncRNAs and constructed a network of lncRNAs-mRNAs and circRNAs-miRNAs to show their interactions. After a series of bioinformatics analyses, we found that low expression of NONHSAT163779 and high expression of circ_0043949 are closely related to the chemoresistance of STRG. Our findings revealed the alteration of expression patterns of mRNAs, lncRNAs, and circRNAs in the secondary temozolomide-resistant glioblastoma for the first time. NONHSAT163779 and hsa_circ_0043949 might be potential therapeutic targets and prognostic biomarkers for the treatment of glioblastoma.

Reverse Engineering Cancer: Inferring Transcriptional Gene Signatures from Copy Number Aberrations with ICAro

The characterization of a gene product function is a process that involves multiple laboratory techniques in order to silence the gene itself and to understand the resulting cellular phenotype via several omics profiling. When it comes to tumor cells, usually the translation process from in vitro characterization results to human validation is a difficult journey. Here, we present a simple algorithm to extract mRNA signatures from cancer datasets, where a particular gene has been deleted at the genomic level, ICAro. The process is implemented as a two-step workflow. The first one employs several filters in order to select the two patient subsets: the inactivated one, where the target gene is deleted, and the control one, where large genomic rearrangements should be absent. The second step performs a signature extraction via a Differential Expression analysis and a complementary Random Forest approach to provide an additional gene ranking in terms of information loss. We benchmarked the system robustness on a panel of genes frequently deleted in cancers, where we validated the downregulation of target genes and found a correlation with signatures extracted with the L1000 tool, outperforming random sampling for two out of six L1000 classes. Furthermore, we present a use case correlation with a published transcriptomic experiment. In conclusion, deciphering the complex interactions of the tumor environment is a challenge that requires the integration of several experimental techniques in order to create reproducible results. We implemented a tool which could be of use when trying to find mRNA signatures related to a gene loss event to better understand its function or for a gene-loss associated biomarker research.

Review: Synthetic scaffolds to control the biochemical, mechanical, and geometrical environment of stem cell-derived brain organoids

Stem cell-derived brain organoids provide a powerful platform for systematic studies of tissue functional architecture and the development of personalized therapies. Here, we review key advances at the interface of soft matter and stem cell biology on synthetic alternatives to extracellular matrices. We emphasize recent biomaterial-based strategies that have been proven advantageous towards optimizing organoid growth and controlling the geometrical, biomechanical, and biochemical properties of the organoid's three-dimensional environment. We highlight systems that have the potential to increase the translational value of region-specific brain organoid models suitable for different types of manipulations and high-throughput applications.

MicroRNA-1225-5p behaves as a tumor suppressor in human glioblastoma via targeting of IRS1

Background

MicroRNAs (miRNAs) play an important role in cancer initiation, progression, and metastasis by directly regulating their target genes.

Materials and methods

In this study, we observed that the miR-1225-5p expression level in glioblastoma tissues was significantly lower as compared with that in normal brain tissues, and its low expression was significantly associated with histopathological grade and poor patient prognosis.

Results

Through establishing a miR-1225-5p overexpression glioblastoma cell line, we found that ectopic overexpression of miR-1225-5p inhibited the proliferation, migration, and invasion of glioblastoma cells in vitro. Moreover, the growth of a glioblastoma xenograft tumor was attenuated by overexpression of miR-1225-5p. Further integrative studies suggested that the insulin receptor substrate 1 (IRS1) was a direct functional target of miR-1225-5p in glioblastoma, and the mRNA and protein levels of IRS1 in six human glioblastoma cell lines (A172, SW1783, U87, LN-229, SW1088, and T98G) were significantly higher as compared with normal human astrocytes.

Conclusion

These results suggest that miR-1225-5p may be a novel candidate for glioblastoma therapy.

Hsp90 inhibitor NMS-E973 exerts the anticancer effect against glioblastoma via induction of PUMA-mediated apoptosis

BACKGROUND

Glioblastoma is one of the most aggressive and common malignancies of the central nervous system in humans. Owing to the correlation of high Hsp90 expression with prognosis and clinical pathology features of diverse types of cancer, targeting Hsp90 with small-molecule inhibitors has become a promising anticancer strategy.

PURPOSE

In this study, we aimed to explore the possibility of anticancer effect of NMS-E973 in giloblastoma and elucidate the mechanism.

METHODS

Cell based MTT assay and colony formation assay were used to detect cell viability. Apoptosis was analyzed by nuclear staining with Hoechst 33258 and Annexin V/propidium iodide staining followed by flow cytometry. Western-blot and RT-PCR were used to detect gene expression. Xenograft assay was used to explore the anticancer effect of NMS-E973 in vivo.

RESULTS

We found that NMS-E973 induces apoptosis and inhibits cell growth in glioblastoma cells in cell culture and xenograft models. As a proapoptotic Bcl-2 member, PUMA was induced by NMS-E973 in a p53-dependent manner in glioblastoma in cell culture, thereby inducing apoptosis in glioblastoma cells. Furthermore, PUMA was induced by NMS-E973 treatment in xenograft tumors, and deficiency in PUMA significantly suppressed the antitumor effects of NMS-E973.

CONCLUSION

Our study suggests that PUMA-mediated apoptosis is important for the therapeutic responses of NMS-E973. Induction of PUMA might be a potential biomarker for predicting NMS-E973 responses.