Phenotypic and molecular states of IDH1 mutation-induced CD24-positive glioma stem-like cells

Mechanism analysis and targeted therapy of IDH gene mutation in glioma

Isocitrate dehydrogenase (IDH) is a pivotal enzyme responsible for catalyzing the oxidative decarboxylation of isocitrate into α-ketoglutarate (α-KG). This enzyme serves as a crucial regulator in the tricarboxylic acid cycle (TCA cycle), acting as a rate-limiting step. Its role extends beyond mere metabolic function, influencing cellular homeostasis and overall cell function. In the past decade, prominent research in cancer genetics has revealed that genes responsible for encoding isocitrate dehydrogenase are commonly mutated across various human malignancies. Significant research in the field has shown that these mutations are commonly found in diseases like glioma, acute myeloid leukemia (AML), cholangiocarcinoma (CCA), chondrosarcoma, and thyroid cancer (TC). As research on IDH progresses, deeper insights into the biological effects of IDH mutations have been gained, unveiling their potential role in tumorigenesis. In addition, IDH mutants' unique activities creates new pathways in tumor metabolism, gene rearrangement, and therapeutic resistance. Currently, innovative molecular targeting strategies for genes bearing mutations in IDH have been devised to enhance the therapeutic efficacy against cancers harboring IDH mutations. These methods represent a promising avenue for improving treatment outcomes in IDH-mutated malignancies. This article mainly summarizes the related research on glioma caused by IDH mutation, and focuses on the biological characteristics and transformation of IDH.

Is modulation of immune checkpoints on glioblastoma-infiltrating myeloid cells a viable therapeutic strategy?

The field of immunology has traditionally focused on immune checkpoint modulation of adaptive immune cells. However, many malignancies such as glioblastoma are mostly devoid of T cells and rather are enriched with immunosuppressive myeloid cells of the innate immune system. While some immune checkpoint targets are shared between adaptive and innate immunity, myeloid-specific checkpoints could also serve as potential therapeutics. To better understand the impact of immune checkpoint blockade on myeloid cells, we systematically summarize the current literature focusing on the direct immunological effects of PD-L1/PD-1, CD24/Siglec-10, collagen/LAIR-1, CX3CL1/CX3CR1, and CXCL10/CXCR3. By synthesizing the molecular mechanisms and the translational implications, we aim to prioritize agents in this category of therapeutics for glioblastoma.

Mesenchymal Properties of Glioma Cell Lines

Screening of cell surface markers of three glioma cell lines (astrocytoma 1321N1, glioblastoma T98g, and glioblastoma astrocytoma U373 MG) was performed. Glioma cells expressed common mesenchymal cell markers, although the expression levels varied between the cell lines. The expression of proneural markers and glioma cancer stem cell markers was very low and also varied. Induction of differentiation towards the mesodermal cell lineages showed effective adipogenic and osteogenic differentiation for only the U373 MG cell line, while the 1321N1 and T98g lines demonstrated weak adipogenic potential and failed to undergo osteogenic differentiation. The obtained results point to the intratumor phenotypical heterogeneity of cells in gliomas and to the differences between the three studied types of gliomas with regard to the content of cells with mesenchymal phenotype.

From mechanism to therapy: the journey of CD24 in cancer

CD24 is a glycosylphosphatidylinositol-anchored protein that is expressed in a wide range of tissues and cell types. It is involved in a variety of physiological and pathological processes, including cell adhesion, migration, differentiation, and apoptosis. Additionally, CD24 has been studied extensively in the context of cancer, where it has been found to play a role in tumor growth, invasion, and metastasis. In recent years, there has been growing interest in CD24 as a potential therapeutic target for cancer treatment. This review summarizes the current knowledge of CD24, including its structure, function, and its role in cancer. Finally, we provide insights into potential clinical application of CD24 and discuss possible approaches for the development of targeted cancer therapies.

MAPP unravels frequent co-regulation of splicing and polyadenylation by RNA-binding proteins and their dysregulation in cancer

Maturation of eukaryotic pre-mRNAs via splicing and polyadenylation is modulated across cell types and conditions by a variety of RNA-binding proteins (RBPs). Although there exist over 1,500 RBPs in human cells, their binding motifs and functions still remain to be elucidated, especially in the complex environment of tissues and in the context of diseases. To overcome the lack of methods for the systematic and automated detection of sequence motif-guided pre-mRNA processing regulation from RNA sequencing (RNA-Seq) data we have developed MAPP (Motif Activity on Pre-mRNA Processing). Applying MAPP to RBP knock-down experiments reveals that many RBPs regulate both splicing and polyadenylation of nascent transcripts by acting on similar sequence motifs. MAPP not only infers these sequence motifs, but also unravels the position-dependent impact of the RBPs on pre-mRNA processing. Interestingly, all investigated RBPs that act on both splicing and 3' end processing exhibit a consistently repressive or activating effect on both processes, providing a first glimpse on the underlying mechanism. Applying MAPP to normal and malignant brain tissue samples unveils that the motifs bound by the PTBP1 and RBFOX RBPs coordinately drive the oncogenic splicing program active in glioblastomas demonstrating that MAPP paves the way for characterizing pre-mRNA processing regulators under physiological and pathological conditions.

Cancer stem cells in brain tumors: From origin to clinical implications

Malignant brain tumors are highly heterogeneous tumors with a poor prognosis and a high morbidity and mortality rate in both children and adults. The cancer stem cell (CSC, also named tumor-initiating cell) model states that tumor growth is driven by a subset of CSCs. This model explains some of the clinical observations of brain tumors, including the almost unavoidable tumor recurrence after initial successful chemotherapy and/or radiotherapy and treatment resistance. Over the past two decades, strategies for the identification and characterization of brain CSCs have improved significantly, supporting the design of new diagnostic and therapeutic strategies for brain tumors. Relevant studies have unveiled novel characteristics of CSCs in the brain, including their heterogeneity and distinctive immunobiology, which have provided opportunities for new research directions and potential therapeutic approaches. In this review, we summarize the current knowledge of CSCs markers and stemness regulators in brain tumors. We also comprehensively describe the influence of the CSCs niche and tumor microenvironment on brain tumor stemness, including interactions between CSCs and the immune system, and discuss the potential application of CSCs in brain-based therapies for the treatment of brain tumors.

Genetic heterogeneity of liver cancer stem cells

Cancer cell heterogeneity is a serious problem in the control of tumor progression because it can cause chemoresistance and metastasis. Heterogeneity can be generated by various mechanisms, including genetic evolution of cancer cells, cancer stem cells (CSCs), and niche heterogeneity. Because the genetic heterogeneity of CSCs has been poorly characterized, the genetic mutation status of CSCs was examined using Exome-Seq and RNA-Seq data of liver cancer. Here we show that different surface markers for liver cancer stem cells (LCSCs) showed a unique propensity for genetic mutations. Cluster of differentiation 133 (CD133)-positive cells showed frequent mutations in the IRF2, BAP1, and ERBB3 genes. However, leucine-rich repeat-containing G protein-coupled receptor 5-positive cells showed frequent mutations in the CTNNB1, RELN, and ROBO1 genes. In addition, some genetic mutations were frequently observed irrespective of the surface markers for LCSCs. BAP1 mutations was frequently observed in CD133-, CD24-, CD13-, CD90-, epithelial cell adhesion molecule-, or keratin 19-positive LCSCs. ASXL2, ERBB3, IRF2, TLX3, CPS1, and NFATC2 mutations were observed in more than three types of LCSCs, suggesting that common mechanisms for the development of these LCSCs. The present study provides genetic heterogeneity depending on the surface markers for LCSCs. The genetic heterogeneity of LCSCs should be considered in the development of LCSC-targeting therapeutics.

Preclinical modeling of lower-grade gliomas

Models for human gliomas prove critical not only to advancing our understanding of glioma biology but also to facilitate the development of therapeutic modalities. Specifically, creating lower-grade glioma (LGG) models has been challenging, contributing to few investigations and the minimal progress in standard treatment over the past decade. In order to reliably predict and validate the efficacies of novel treatments, however, LGG models need to adhere to specific standards that recapitulate tumor genetic aberrations and micro-environment. This underscores the need to revisit existing models of LGG and explore prospective models that may bridge the gap between preclinical insights and clinical translation. This review first outlines a set of criteria aimed to address the current challenges hindering model development. We then evaluate the strengths and weaknesses of existing preclinical models of LGG with respect to these established standards. To conclude, the review discusses potential future directions for integrating existing models to maximize the exploration of disease mechanisms and therapeutics development.

The SW480 cell line, overexpressing PIWIL2 gene, maintains the expression of stemness and proliferation genes in the mice xenografts

Aim

This study aims to confirm previous fundamental in vitro findings about the PIWIL2 gene by investigating the effects of its overexpression on cell cycle, proliferation, apoptosis, and stem cell expression markers in colorectal cancer cells (CRC cells) at in vivo level.

Background

PIWIL2 has a critical role in maintaining cellular stemness and proliferation. PIWIL2 is an oncogene whose expression in CRC is associated with the occurrence, metastasis, and poor prognosis.

Methods

SW480 cells harboring expression vectors with/without PIWIL2 were cultured and inoculated in BALB/c nude mice. Tumor formation and growth were monitored every 3 days. On the 28th day after inoculation, the tumors were harvested for their total RNA extraction, and the expression profiling of the candidate genes was performed by Real-time PCR.

Results

Our results for the expression profiling of the xenografted tumors showed a significant increase in the expression of cancer stem cell markers, including CD24, CD133, and pluripotency marker SOX2 in the PIWIL2 over-expressing xenografts, compared to the control cell line. Moreover, PIWIL2 dramatically promoted the anti-apoptotic pathway by inducing STAT3 and BCL2-L1 genes in the PIWIL2 over-expressing xenografts, along with the up-regulation of Cyclin D1 and Ki-67 genes.

Conclusion

This research supports our prior in vitro findings, highlighting the critical role that PIWIL2 plays in the development of CRC and its substantial promise as a leading candidate for CRC-targeted therapy.

Establishment of a cell senescence related prognostic model for predicting prognosis in glioblastoma

Background: Glioblastoma (GBM) is highly malignant and has a worse prognosis with age, and next-generation sequencing (NGS) provides us with a huge amount of information about GBM. Materials and Methods: Through the enrichment scores of cell senescence-related pathways, we constructed a consensus matrix and mined molecular subtypes and explored the differences in pathological, immune/pathway and prognostic. Also we identified key genes related to cell senescence characteristics using least absolute shrinkage and selection operator (Lasso) regression and univariate COX regression analysis models. The use of risk factor formats to construct clinical prognostic models also explored the differences in immunotherapy/chemotherapy within the senescence-related signatures score (SRS.score) subgroups. Decision trees built with machine learning to identify the main factors affecting prognosis have further improved the prognosis model and survival prediction. Results: We obtained seven prognostic-related pathways related to cell senescence. We constructed four different molecular subtypes and found patients with subtype C1 had the worst prognosis. C4 had the highest proportion of patients with IDH mutations. 1005 differentially expressed genes (DEGs) were analyzed, and finally 194 Risk genes and 38 Protective genes were obtained. Eight key genes responsible for cell senescence were finally identified. The clinical prognosis model was established based on SRS.score, and the prognosis of patients with high SRS.score was worse. SRS.score and age were the vital risk factors for GBM patients through decision tree model mining. Conclusion: We constructed a clinical prognosis model that could provide high prediction accuracy and survival prediction ability for adjuvant treatment of patients with GBM.

Single-nucleus transcriptomics of IDH1- and TP53-mutant glioma stem cells displays diversified commitment on invasive cancer progenitors

Glioma is a devastating brain tumor with a high mortality rate attributed to the glioma stem cells (GSCs) possessing high plasticity. Marker mutations in isocitrate dehydrogenase type 1 (IDH1) and tumor protein 53 (TP53) are frequent in gliomas and impact the cell fate decisions. Understanding the GSC heterogeneity within IDH1- and TP53- mutant tumors may elucidate possible treatment targets. Here, we performed single-nucleus transcriptomics of mutant and wild-type glioma samples sorted for Sox2 stem cell marker. For the first time the rare subpopulations of Sox2 + IDH1- and TP53-mutant GSCs were characterized. In general, GSCs contained the heterogeneity root subpopulation resembling active neural stem cells capable of asymmetric division to quiescent and transit amplifying cell branches. Specifically, double-mutant GSCs revealed the commitment on highly invasive oligodendrocyte- and astroglia-like progenitors. Additionally, double-mutant GSCs displayed upregulated markers of collagen synthesis, altered lipogenesis and high migration, while wild-type GSCs expressed genes related to ATP production. Wild-type GSC root population was highly heterogeneous and lacked the signature marker expression, thus glioblastoma treatment should emphasize on establishing differentiation protocol directed against residual GSCs. For the more differentiated IDH1- and TP53-mutant gliomas we suggest therapeutic targeting of migration molecules, such as CD44.