The Interaction between DNMT1 and High-Mannose CD133 Maintains the Slow-Cycling State and Tumorigenic Potential of Glioma Stem Cell

Protocol for sorting cancer stem cells using a combination of anti-CD133 antibody and lectin cyanovirin-N

CD133 is widely used as a marker to isolate cancer stem cells (CSCs). However, the structural ambiguity of N-glycan of CD133 limits its application in the isolation of CSCs. Here, we present a protocol to sort CSCs from tumor samples by combining CD133 with α-1,2-high-mannose type glycan chains. We describe steps for purifying and biotinylating cyanovirin-N (CVN) proteins and sorting tumor cells and CD133+α-1,2-Man+ (α-1,2-linked mannose+) cells to provide more specific markers for CSCs. For complete details on the use and execution of this protocol, please refer to Wei et al.1.

Marine Lectins and Lectin-like Proteins as Promising Molecules Targeting Aberrant Glycosylation Signatures in Human Brain Tumors

Glycosylation is a ubiquitous and the most structurally diverse post-translational modification of proteins. High levels of phenotypic heterogeneity in brain tumors affect the biosynthetic pathway of glycosylation machinery, resulting in aberrant glycosylation patterns. Traditionally, unique glycocode readers, carbohydrate-binding proteins, have been used to identify differentially expressed carbohydrate determinants associated with the tumor cell surface. However, identifying novel distinctive glycosylation signatures in brain tumors requires the timely development of molecular tools capable of targeting them. We classified marine-derived lectins and lectin-like molecules according to their ability to cover aberrant glycosylation patterns in brain tumors to encourage exploration of the potential of these molecules for precision diagnostics and personalized therapy.

Glioblastoma Sensitization to Therapeutic Effects by Glutamine Deprivation Depends on Cellular Phenotype and Metabolism

Glutamine plays an important role in tumor metabolism. It is known that the core region of solid tumors is deprived of glutamine, which affects tumor growth and spread. Here we investigated the effect of glutamine deprivation on cellular metabolism and sensitivity of human glioblastoma cells U87MG and T98G to drugs of various origin: alkylating cytostatic agent temozolomide; cytokine TRAIL DR5-B - agonist of the DR5 receptor; and GMX1778 - a targeted inhibitor of the enzyme nicotinamide phosphoribosyltransferase (NAMPT), limiting NAD biosynthesis. Bioinformatics analysis of the cell transcriptomes showed that U87MG cells have a more differentiated phenotype than T98G, and also differ in the expression profile of the genes associated with glutamine metabolism. Upon glutamine deprivation, growth rate of the U87MG and T98G cells decreased. Analysis of cellular metabolism by FLIM microscopy of NADH as well as assessment of lactate content in the medium showed that glutamine deprivation shifted metabolic status of the U87MG cells towards glycolysis. This was accompanied by the increase in expression of the stemness marker CD133, which collectively could indicate de-differentiation of these cells. At the same time, we observed increase in both expression of the DR5 receptor and sensitivity of the U87MG cells to DR5-B. On the contrary, glutamine deprivation of T98G cells induced metabolic shift towards oxidative phosphorylation, decrease in the DR5 expression and resistance to DR5-B. The effects of NAMPT inhibition also differed between the two cell lines and were opposite to the effects of DR5-B: upon glutamine deprivation, U87MG cells acquired resistance, while T98G cells were sensitized to GMX1778. Thus, phenotypic and metabolic differences between the two human glioblastoma cell lines caused divergent metabolic changes and contrasting responses to different targeted drugs during glutamine deprivation. These data should be considered when developing treatment strategies for glioblastoma via drug-mediated deprivation of amino acids, as well as when exploring novel therapeutic targets.

Elevated α-1,2-mannosidase MAN1C1 in glioma stem cells and its implications for immunological changes and prognosis in glioma patients

Glioblastoma multiforme (GBM) is the most aggressive type of primary brain tumor, and the presence of glioma stem cells (GSCs) has been linked to its resistance to treatments and recurrence. Additionally, aberrant glycosylation has been implicated in the aggressiveness of cancers. However, the influence and underlying mechanism of N-glycosylation on the GSC phenotype and GBM malignancy remain elusive. Here, we performed an in-silico analysis approach on publicly available datasets to examine the function of N-glycosylation-related genes in GSCs and gliomas, accompanied by a qRT-PCR validation experiment. We found that high α-1,2-mannosidase MAN1C1 is associated with immunological functions and worse survival of glioma patients. Differential gene expression analysis and qRT-PCR validation revealed that MAN1C1 is highly expressed in GSCs. Furthermore, higher MAN1C1 expression predicts worse outcomes in glioma patients. Also, MAN1C1 expression is increased in the perinecrotic region of GBM and is associated with immunological and inflammatory functions, a hallmark of the GBM mesenchymal subtype. Further analysis confirmed that MAN1C1 expression is closely associated with infiltrating immune cells and disrupted immune response in the GBM microenvironment. These suggest that MAN1C1 is a potential biomarker for gliomas and may be important as an immunotherapeutic target for GBM.

Brain gliomas: Diagnostic and therapeutic issues and the prospects of drug-targeted nano-delivery technology

Glioma is the most common intracranial malignant tumor, with severe difficulty in treatment and a low patient survival rate. Due to the heterogeneity and invasiveness of tumors, lack of personalized clinical treatment design, and physiological barriers, it is often difficult to accurately distinguish gliomas, which dramatically affects the subsequent diagnosis, imaging treatment, and prognosis. Fortunately, nano-delivery systems have demonstrated unprecedented capabilities in diagnosing and treating gliomas in recent years. They have been modified and surface modified to efficiently traverse BBB/BBTB, target lesion sites, and intelligently release therapeutic or contrast agents, thereby achieving precise imaging and treatment. In this review, we focus on nano-delivery systems. Firstly, we provide an overview of the standard and emerging diagnostic and treatment technologies for glioma in clinical practice. After induction and analysis, we focus on summarizing the delivery methods of drug delivery systems, the design of nanoparticles, and their new advances in glioma imaging and treatment in recent years. Finally, we discussed the prospects and potential challenges of drug-delivery systems in diagnosing and treating glioma.

Identification of TNFAIP6 as a reliable prognostic indicator of low-grade glioma

Glioma is the most common primary malignant tumor in the brain, characterizing by high disability rate and high recurrence rate. Although low-grade glioma (LGG) has a relative benign biological behavior, the prognosis of LGG patients still varies greatly. Glioma stem cells (GSCs) are considered as the chief offenders of glioma cell proliferation, invasion and resistance to therapies. Our study screened a series of glioma stem cell-related genes (GSCRG) based on mDNAsi and WCGNA, and finally established a reliable single-gene prognostic model through 101 combinations of 10 machine learning methods. Our result suggested that the expression level of TNFAIP6 is negatively correlated with the prognosis of LGG patients, which may be the result of pro-cancer signaling pathways activation and immunosuppression. In general, this study revealed that TNFAIP6 is a robust and valuable prognostic factor in LGG, and may be a new target for LGG treatment.

Emerging roles of prominin-1 (CD133) in the dynamics of plasma membrane architecture and cell signaling pathways in health and disease

Prominin-1 (CD133) is a cholesterol-binding membrane glycoprotein selectively associated with highly curved and prominent membrane structures. It is widely recognized as an antigenic marker of stem cells and cancer stem cells and is frequently used to isolate them from biological and clinical samples. Recent progress in understanding various aspects of CD133 biology in different cell types has revealed the involvement of CD133 in the architecture and dynamics of plasma membrane protrusions, such as microvilli and cilia, including the release of extracellular vesicles, as well as in various signaling pathways, which may be regulated in part by posttranslational modifications of CD133 and its interactions with a variety of proteins and lipids. Hence, CD133 appears to be a master regulator of cell signaling as its engagement in PI3K/Akt, Src-FAK, Wnt/β-catenin, TGF-β/Smad and MAPK/ERK pathways may explain its broad action in many cellular processes, including cell proliferation, differentiation, and migration or intercellular communication. Here, we summarize early studies on CD133, as they are essential to grasp its novel features, and describe recent evidence demonstrating that this unique molecule is involved in membrane dynamics and molecular signaling that affects various facets of tissue homeostasis and cancer development. We hope this review will provide an informative resource for future efforts to elucidate the details of CD133's molecular function in health and disease.

Functional Roles of CD133: More than Stemness Associated Factor Regulated by the Microenvironment

CD133 protein has been one of the most used surface markers to select and identify cancer cells with stem-like features. However, its expression is not restricted to tumoral cells; it is also expressed in differentiated cells and stem/progenitor cells in various normal tissues. CD133 participates in several cellular processes, in part orchestrating signal transduction of essential pathways that frequently are dysregulated in cancer, such as PI3K/Akt signaling and the Wnt/β-catenin pathway. CD133 expression correlates with enhanced cell self-renewal, migration, invasion, and survival under stress conditions in cancer. Aside from the intrinsic cell mechanisms that regulate CD133 expression in each cellular type, extrinsic factors from the surrounding niche can also impact CD33 levels. The enhanced CD133 expression in cells can confer adaptive advantages by amplifying the activation of a specific signaling pathway in a context-dependent manner. In this review, we do not only describe the CD133 physiological functions known so far, but importantly, we analyze how the microenvironment changes impact the regulation of CD133 functions emphasizing its value as a marker of cell adaptability beyond a cancer-stem cell marker.

The Interaction between Collagen 1 and High Mannose Type CD133 Up-Regulates Glutamine Transporter SLC1A5 to Promote the Tumorigenesis of Glioblastoma Stem Cells

Targeting the niche components surrounding glioblastoma stem cells (GSCs) helps to develop more effective glioblastoma treatments. However, the mechanisms underlying the crosstalk between GSCs and microenvironment remain largely unknown. Clarifying the extracellular molecules binding to GSCs marker CD133 helps to elucidate the mechanism of the communication between GSCs and the microenvironment. Here, it is found that the extracellular domain of high mannose type CD133 physically interacts with Collagen 1 (COL1) in GSCs. COL1, mainly secreted by cancer-associated fibroblasts, is a niche component for GSCs. COL1 enhances the interaction between CD133 and p85 and activates Akt phosphorylation. Activation of Akt pathway increases transcription factor ATF4 protein level, subsequently enhances SLC1A5-dependent glutamine uptake and glutathione synthesis. The inhibition of CD133-COL1 interaction or down-regulation of SLC1A5 reduces COL1-accelerated GSCs self-renewal and tumorigenesis. Analysis of glioma samples reveals that the level of COL1 is correlated with histopathological grade of glioma and the expression of SLC1A5. Collectively, COL1, a niche component for GSCs, enhances the tumorigenesis of GSCs partially through CD133-Akt-SLC1A5 signaling axis, providing a new mechanism underlying the cross-talk between GSCs and extracellular matrix (ECM) microenvironment.

The Role of Cytokines in Activation of Tumour-promoting Pathways and Emergence of Cancer Drug Resistance

Scientists are constantly researching and launching potential chemotherapeutic agents as an irreplaceable weapon to fight the battle against cancer. Despite remarkable advancement over the past several decades to wipe out cancer through early diagnosis, proper prevention, and timely treatment, cancer is not ready to give up and leave the battleground. It continuously tries to find some other way to give a tough fight for its survival, either by escaping from the effect of chemotherapeutic drugs or utilising its own chemical messengers like cytokines to ensure resistance. Cytokines play a significant role in cancer cell growth and progression, and the present article highlights their substantial contribution to mechanisms of resistance toward therapeutic drugs. Multiple clinical studies have even described the importance of specific cytokines released from cancer cells as well as stromal cells in conferring resistance. Herein, we discuss the different mechanism behind drug resistance and the crosstalk between tumor development and cytokines release and their contribution to showing resistance towards chemotherapeutics. As a part of this review, different approaches to cytokines profile have been identified and employed to successfully target new evolving mechanisms of resistance and their possible treatment options.

Loss of α-1,2-mannosidase MAN1C1 promotes tumorigenesis of intrahepatic cholangiocarcinoma through enhancing CD133-FIP200 interaction

CD133 is widely used as a marker to isolate tumor-initiating cells in many types of cancers. The structure of N-glycan on CD133 is altered during the differentiation of tumor-initiating cells. However, the relationship between CD133 N-glycosylation and stem cell characteristics remains elusive. Here, we found that the level of α-1,2-mannosylated CD133 was associated with the level of stemness genes in intrahepatic cholangiocarcinoma (iCCA) tissues. α-1,2-mannosylated CD133+ cells possessed the characteristics of tumor-initiating cells. The loss of the Golgi α-mannosidase I coding gene MAN1C1 resulted in the formation of α-1,2-mannosylated CD133 in iCCA-initiating cells. Mechanistically, α-1,2-mannosylation promoted the cytoplasmic distribution of CD133 and enhanced the interaction between CD133 and the autophagy gene FIP200, subsequently promoting the tumorigenesis of α-1,2-mannosylated CD133+ cells. Analysis of iCCA samples showed that the level of cytoplasmic CD133 was associated with poor iCCA prognosis. Collectively, α-1,2-mannosylated CD133 is a functional marker of iCCA-initiating cells.

Biological function, regulatory mechanism, and clinical application of mannose in cancer

Studies examining the regulatory roles and clinical applications of monosaccharides other than glucose in cancer have been neglected. Mannose, a common type of monosaccharide found in human body fluids and tissues, primarily functions in protein glycosylation rather than carbohydrate metabolism. Recent research has demonstrated direct anticancer effects of mannose in vitro and in vivo. Simply supplementing cell culture medium or drinking water with mannose achieved these effects. Moreover, mannose enhances the effectiveness of current cancer treatments including chemotherapy, radiotherapy, targeted therapy, and immune therapy. Besides the advancements in basic research on the anticancer effects of mannose, recent studies have reported its application as a biomarker for cancer or in the delivery of anticancer drugs using mannose-modified drug delivery systems. This review discusses the progress made in understanding the regulatory roles of mannose in cancer progression, the mechanisms underlying its anticancer effects, and its current application in cancer diagnosis and treatment.

Targeting drug-tolerant cells: A promising strategy for overcoming acquired drug resistance in cancer cells

Drug resistance remains the greatest challenge in improving outcomes for cancer patients who receive chemotherapy and targeted therapy. Surmounting evidence suggests that a subpopulation of cancer cells could escape intense selective drug treatment by entering a drug-tolerant state without genetic variations. These drug-tolerant cells (DTCs) are characterized with a slow proliferation rate and a reversible phenotype. They reside in the tumor region and may serve as a reservoir for resistant phenotypes. The survival of DTCs is regulated by epigenetic modifications, transcriptional regulation, mRNA translation remodeling, metabolic changes, antiapoptosis, interactions with the tumor microenvironment, and activation of signaling pathways. Thus, targeting the regulators of DTCs opens a new avenue for the treatment of therapy-resistant tumors. In this review, we first provide an overview of common characteristics of DTCs and the regulating networks in DTCs development. We also discuss the potential therapeutic opportunities to target DTCs. Last, we discuss the current challenges and prospects of the DTC-targeting approach to overcome acquired drug resistance. Reviewing the latest developments in DTC research could be essential in discovering of methods to eliminate DTCs, which may represent a novel therapeutic strategy for preventing drug resistance in the future.

An Overview of CD133 as a Functional Unit of Prognosis and Treatment Resistance in Glioblastoma

Biomarkers for resistance in Glioblastoma multiforme (GBM) are lacking, and progress in the clinic has been slow to arrive. CD133 (prominin-1) is a membrane-bound glycoprotein on the surface of cancer stem cells (CSCs) that has been associated with poor prognosis, therapy resistance, and tumor recurrence in GBM. Due to its connection to CSCs, to which tumor resistance and recurrence have been partially attributed in GBM, there is a growing field of research revolving around the potential role of CD133 in each of these processes. However, despite encouraging results in vitro and in vivo, the biological interplay of CD133 with these components is still unclear, causing a lack of clinical application. In parallel, omic data from biospecimens that include CD133 are beginning to emerge, increasing the importance of understanding CD133 for the effective use of these highly dimensional data sets. Given the significant mechanistic overlap, prioritization of the most robust findings is necessary to optimize the transition of CD133 to clinical applications using patient-derived biospecimens. As a result, this review aims to compile and analyze the current research regarding CD133 as a functional unit in GBM, exploring its connections to prognosis, the tumor microenvironment, tumor resistance, and tumor recurrence.

The role of Algerian Ephedra alata ethanolic extract in inhibiting the growth of breast cancer cells by inducing apoptosis in a p53- dependent pathway

Background

Ephedra alata, a member of the Ephedraceae family, was used to treat different diseases and it might be shown a strong efficacy to inhibit cancer cell lines.

Methods

Due to the limited research available about this plant, the objective of this research was to evaluate the antioxidant, cytotoxic and apoptotic effects of Ephedra alata ethanolic extract (EAEE), against different human cancer cell lines.

Results

EAEE inhibited the growth of the liver (HepG2), breast (MCF-7), and colon cancer cells (Caco-2). MCF-7 cells with an IC₅₀ of 153 µg/ml, were the most sensitive to the extract. Furthermore, exploration using flow cytometry using Annexin V-FITC/PI assay demonstrated that EAEE caused death for all human cancer cells mainly through apoptosis. Very interestingly, qRT-PCR analysis using the ΔΔCt method revealed that four genes, Bax, p21, RB1, and TP53 were up-regulated in MCF-7 cells treated either with EAEE or S-FU drug. These findings let us believe that the mechanism by which EAEE kills breast cancer cells seems to be apoptosis via a P53-dependent manner, which involved intrinsic pathways through the induction of Bax, p21, and RB1.

Conclusions

EAEE exhibits good biological properties in contradiction of HepG-2, MCF-7, and Caco-2 cell lines. This study appoints for the first time that EAEE increases the expression in MCF-7 cells of p53 and three more genetic traits that control cellular proliferation and apoptosis. Therefore, this plant could serve as a potential source to find new pro-apoptotic drugs for cancer treatment.

Targeting epigenetic regulators to overcome drug resistance in cancers

Drug resistance is mainly responsible for cancer recurrence and poor prognosis. Epigenetic regulation is a heritable change in gene expressions independent of nucleotide sequence changes. As the common epigenetic regulation mechanisms, DNA methylation, histone modification, and non-coding RNA regulation have been well studied. Increasing evidence has shown that aberrant epigenetic regulations contribute to tumor resistance. Therefore, targeting epigenetic regulators represents an effective strategy to reverse drug resistance. In this review, we mainly summarize the roles of epigenetic regulation in tumor resistance. In addition, as the essential factors for epigenetic modifications, histone demethylases mediate the histone or genomic DNA modifications. Herein, we comprehensively describe the functions of the histone demethylase family including the lysine-specific demethylase family, the Jumonji C-domain-containing demethylase family, and the histone arginine demethylase family, and fully discuss their regulatory mechanisms related to cancer drug resistance. In addition, therapeutic strategies, including small-molecule inhibitors and small interfering RNA targeting histone demethylases to overcome drug resistance, are also described.

Slow-cycling murine melanoma cells display plasticity and enhanced tumorigenicity in syngeneic transplantation assay

Slow-cycling cancer cells (SCC) contribute to the aggressiveness of many cancers, and their invasiveness and chemoresistance pose a great therapeutic challenge. However, in melanoma, their tumor-initiating abilities are not fully understood. In this study, we used the syngeneic transplantation assay to investigate the tumor-initiating properties of melanoma SCC in the physiologically relevant in vivo settings. For this we used B16-F10 murine melanoma cell line where we identified a small fraction of SCC. We found that, unlike human melanoma, the murine melanoma SCC were not marked by the high expression of the epigenetic enzyme Jarid1b. At the same time, their slow-cycling phenotype was a temporary state, similar to what was described in human melanoma. Progeny of SCC had slightly increased doxorubicin resistance and altered expression of melanogenesis genes, independent of the expression of cancer stem cell markers. Single-cell expansion of SCC revealed delayed growth and reduced clone formation when compared to non-SCC, which was further confirmed by an in vitro limiting dilution assay. Finally, syngeneic transplantation of 10 cells in vivo established that SCC were able to initiate growth in primary recipients and continue growth in the serial transplantation assay, suggesting their self-renewal nature. Together, our study highlights the high plasticity and tumorigenicity of murine melanoma SCC and suggests their role in melanoma aggressiveness.

AQP5 complements LGR5 to determine the fates of gastric cancer stem cells through regulating ULK1 ubiquitination

BACKGROUND

Cancer stem cells (CSCs) are regarded as the "seed cells" for tumorigenesis, metastasis, recurrence and drug resistance. However, specific surface markers of CSCs of different origins have not been documented.

METHODS

Single-cell sequencing was used to analyze the highly expressed genes in cancer stem cells of gastric cancer patients, and it was verified that AQP5 was specifically highly expressed in gastric cancer stem cells (GC-CSCs) in vivo and in vitro. The effect of AQP5-promoting LGR5 on the malignant biological function of GC-CSCs was investigated. The mechanism by which AQP5 affects GC-CSCs was explored through transcriptome sequencing, proteomic detection, mass spectrometry, etc. RESULTS: We report the identification and validation of AQP5 as a potentially specific surface marker of GC-CSCs. AQP5 was significantly upregulated in CSCs isolated from gastric cancer patients and in spheroid cells, and AQP5 was coexpressed with the canonical stem marker LGR5. Biologically, AQP5 promoted the sphere formation, proliferation, migration and invasion of GC cells in vitro and enhanced tumorigenesis in vivo. Furthermore, AQP5 coordinated with LGR5 and synergistically promoted the tumorigenesis of GC-CSCs. At the mechanistic level, AQP5 activated autophagy by inducing the LC3I/LC3II transformation in GC-CSCs, which was crucial for the biological functions of AQP5. Finally, we demonstrated that AQP5 recruited the E3 ligase TRIM21 to the key autophagy protein ULK1 and induced the K63-mediated ubiquitination of ULK1.

CONCLUSIONS

We elucidate a novel surface marker, AQP5, which is specifically expressed by GC-CSCs. Furthermore, our study creates a link between AQP5 and LGR5 and highlights the necessity of targeting both surface markers simultaneously as a promising approach for the treatment of gastric cancer patients.