Cancer stem cell definitions and terminology: the devil is in the details

MiR-326: Role and significance in brain cancers

MicroRNAs (miRNAs) are small non-coding RNAs that act as critical regulators of gene expression by repressing mRNA translation. The role of miRNAs in cell physiology spans from cell cycle control to cell proliferation and differentiation, both during development and in adult tissues. Accordingly, dysregulated expression of miRNAs has been reported in several diseases, including cancer, where miRNAs can act as oncogenes or oncosuppressors. Of note, miRNA signatures are also under investigation for classification, diagnosis, and prognosis of cancer patients. Brain tumours are primarily associated with poor prognosis and high mortality, highlighting an urgent need for novel diagnostic, prognostic, and therapeutic tools. Among miRNAs investigated in brain tumours, miR-326 has been shown to act as a tumour suppressor in adult and paediatric brain cancers. In this review, we describe the role of miR-326 in malignant as well as benign cancers originating from brain tissue. In addition, since miR-326 expression can be regulated by other non-coding RNA species, adding a further layer of regulation in the cancer-promoting axis, we discuss this miRNA's role in targeted therapy for brain cancers.

Elastic properties of leukemic cells linked to maturation stage and integrin activation

Acute myeloid leukemia (AML) remains challenging to cure. In addition to mutations that alter cell functioning, biophysical properties are modulated by external cues. In particular, membrane proteins that interact with the bone marrow niche can induce cellular changes. Here, we develop an atomic force microscopy (AFM) approach to measure non-adherent AML cell mechanical properties. The Young's modulus of the AML cell line, THP-1, increased in response to retronectin, whereas knock-out of the adhesion protein ITGB1 resulted in no response to retronectin. Confocal microscopy revealed different actin cytoskeleton morphologies for wild-type and ITGB1 knock-out cells exposed to retronectin. These results indicate that ITGB1 mediates stimuli-induced cellular mechanoresponses through cytoskeletal changes. We next used AFM to investigate the elastic properties of primary AML cells and found that more committed cells had lower Young's moduli than immature AMLs. Overall, this provides a platform for investigating the molecular mechanisms involved in leukemic cell mechanoresponse.

3D cell culture models: how to obtain and characterize the main models

For many years, the gold standard in the study of malignant tumors has been the in vitro culture of tumor cells, in vivo xenografts or genetically modified animal models. Meanwhile, three-dimensional cell models (3D cultures) have been added to the arsenal of modern biomedical research. 3D cultures reproduce tissue-specific features of tissue topology. This makes them relevant tissue models in terms of cell differentiation, metabolism and the development of drug resistance. Such models are already being used by many research groups for both basic and translational research, and may substantially reduce the number of animal studies, for example in the field of oncological research. In the current literature, 3D cultures are classified according to the technique of their formation (with or without a scaffold), cultivation conditions (static or dynamic), as well as their cellular organization and function. In terms of cellular organization, 3D cultures are divided into "spheroid models", "organoids", "organs-on-a-chip" and "microtissues". Each of these models has its own unique features, which should be taken into account when using a particular model in an experiment. The simplest 3D cultures are spheroid models which are floating spherical cell aggregates. An organoid is a more complex 3D model, in which a self-organizing 3D structure is formed from stem cells (SCs) capable of self-renewal and differentiation within the model. Organ-on-a-chip models are chips of microfluidic systems that simulate dynamic physical and biological processes found in organs and tissues in vitro. By combining different cell types into a single structure, spheroids and organoids can act as a basis for the formation of a microtissue - a hybrid 3D model imitating a specific tissue phenotype and containing tissue-specific extracellular matrix (ECM) components. This review presents a brief history of 3D cell culture. It describes the main characteristics and perspectives of the use of "spheroid models", "organoids", "organ-on-a-chip" models and "microtissues" in immune oncology research of solid tumors.

State-of-the-Art Liver Cancer Organoids: Modeling Cancer Stem Cell Heterogeneity for Personalized Treatment

Liver cancer poses a global health challenge with limited therapeutic options. Notably, the limited success of current therapies in patients with primary liver cancers (PLCs) may be attributed to the high heterogeneity of both hepatocellular carcinoma (HCCs) and intrahepatic cholangiocarcinoma (iCCAs). This heterogeneity evolves over time as tumor-initiating stem cells, or cancer stem cells (CSCs), undergo (epi)genetic alterations or encounter microenvironmental changes within the tumor microenvironment. These modifications enable CSCs to exhibit plasticity, differentiating into various resistant tumor cell types. Addressing this challenge requires urgent efforts to develop personalized treatments guided by biomarkers, with a specific focus on targeting CSCs. The lack of effective precision treatments for PLCs is partly due to the scarcity of ex vivo preclinical models that accurately capture the complexity of CSC-related tumors and can predict therapeutic responses. Fortunately, recent advancements in the establishment of patient-derived liver cancer cell lines and organoids have opened new avenues for precision medicine research. Notably, patient-derived organoid (PDO) cultures have demonstrated self-assembly and self-renewal capabilities, retaining essential characteristics of their respective in vivo tissues, including both inter- and intratumoral heterogeneities. The emergence of PDOs derived from PLCs serves as patient avatars, enabling preclinical investigations for patient stratification, screening of anticancer drugs, efficacy testing, and thereby advancing the field of precision medicine. This review offers a comprehensive summary of the advancements in constructing PLC-derived PDO models. Emphasis is placed on the role of CSCs, which not only contribute significantly to the establishment of PDO cultures but also faithfully capture tumor heterogeneity and the ensuing development of therapy resistance. The exploration of PDOs' benefits in personalized medicine research is undertaken, including a discussion of their limitations, particularly in terms of culture conditions, reproducibility, and scalability.

SLC13A5 plays an essential role in the energy shift to oxidative phosphorylation in cisplatin-resistant mesothelioma stem cells

Mesothelioma is a highly aggressive tumor affecting an increasing number of patients worldwide. Owing to the poor clinical outcomes associated with current therapies, the development of novel therapies that target cancer stem cells (CSCs) is desirable. Here, we examined the applicability of our previously established hydrogel-based rapid CSC generation method to human mesothelioma cell lines and further analyzed the characteristics of the induced mesothelioma stem cell (MesoSC) -like cells. Human mesothelioma cell lines cultured on hydrogels presented increased expression of pan-stem cell markers and acquired spheroid formation and early tumorigenicity, suggesting that MesoSC-like cells are highly malignant. Microarray analysis demonstrated that the expression of SLC13A5, a citrate transporter involved in TCA cycle, was significantly induced in the resulting MesoSC-like cells. The overexpression of SLC13A5 resulted in a metabolic shift toward oxidative phosphorylation, increased phosphorylation of ERK and YAP, and increased SOX2 expression, leading to increased cisplatin resistance. scRNA-seq database analysis revealed that clinical mesothelioma samples contained a small number of SLC13A5-expressing cells. Our findings suggest that the hydrogel-based CSC generation method is also effective for human mesothelioma cells and that SLC13A5 may contribute to MesoSC survival. The new properties of MesoSCs revealed in this study may provide clues for establishing future treatments.

Single-cell RNA sequencing and machine learning provide candidate drugs against drug-tolerant persister cells in colorectal cancer

Drug resistance often stems from drug-tolerant persister (DTP) cells in cancer. These cells arise from various lineages and exhibit complex dynamics. However, effectively targeting DTP cells remains challenging. We used single-cell RNA sequencing (scRNA-Seq) data and machine learning (ML) models to identify DTP cells in patient-derived organoids (PDOs) and computationally screened candidate drugs targeting these cells in familial adenomatous polyposis (FAP), associated with a high risk of colorectal cancer. Three PDOs (benign and malignant tumor organoids and a normal organoid) were evaluated using scRNA-Seq. ML models constructed based on public scRNA-Seq data classified DTP versus non-DTP cells. Candidate drugs for DTP cells in a malignant tumor organoid were identified from public drug sensitivity data. From FAP scRNA-Seq data, a specific TC1 cell cluster in tumor organoids was identified. The ML model identified up to 36 % of TC1 cells as DTP cells, a higher proportion than those for other clusters. A viability assay using a malignant tumor organoid demonstrated that YM-155 and THZ2 exert synergistic effects with trametinib. The constructed ML model is effective for DTP cell identification based on scRNA-Seq data for FAP and provides candidate treatments. This approach may improve DTP cell targeting in the treatment of colorectal and other cancers.

The integrative genomic and functional immunological analyses of colorectal cancer initiating cells to modulate stemness properties and the susceptibility to immune responses

BACKGROUND

Colorectal cancer (CRC) initiating cells (CICs) possess self-renewal capabilities and are pivotal in tumor recurrence and resistance to conventional therapies, including immunotherapy. The mechanisms underlying their interaction with immune cells remain unclear.

METHODS

We conducted a multi-omics analysis-encompassing DNA methylation, total RNA sequencing, and microRNAs (miRNAs; N = 800) profiling on primary CICs and differentiated tumor cell lines, including autologous pairs. Functional immunological assays were performed to assess the impact of miRNA modulation.

RESULTS

CICs exhibited distinct methylation patterns, transcriptomic profiles, and miRNA expressions compared to differentiated tumor cells (p < 0.05 or 0.01). Notably, miRNA-15a and -196a were implicated in regulating tumorigenic pathways, such as epithelial-to-mesenchymal transition (EMT), TGF-β signaling, and immune modulation. The transfection of CICs with miRNA mimics led to the downregulation of oncogenic EMT markers (CRKL, lncRNA SOX2-OT, JUNB, SMAD3) and TGF-β pathway, resulting in a significant reduction of the in vitro proliferation and the tumorigenicity and migration in a zebrafish xenograft model. Additionally, miRNA-15a enhanced the expression of antigen processing machinery and decreased the expression of immune checkpoints (PD-L1, PD-L2, CTLA-4) and immunosuppressive cytokines (IL-4). The co-culture of HLA-matched lymphocytes with CICs overexpressing the miRNA-15a, elicited robust tumor-specific immune responses, characterized by a shift toward central and effector memory T cell phenotypes and prevented their terminal differentiation and exhaustion. The combination of miRNA modulation with Indoleamine 2,3-dioxygenase blockade and immunomodulating agents further potentiated these effects.

CONCLUSIONS

Our study demonstrates that the modulation of miRNA-15a in CICs not only suppresses the tumorigenic properties but also enhances their visibility to the immune system by upregulating antigen presentation and reducing immunomodulatory molecules. These findings suggest that combining miRNA modulation with epigenetic or immunomodulatory agents holds significant promise for overcoming treatment resistance in CRC.

Molecule interacting with CasL-2 enhances tumor progression and alters radiosensitivity in cervical cancer

OBJECTIVE

Cervical cancer is a common malignancy among women, and radiotherapy remains a primary treatment modality across all disease stages. However, resistance to radiotherapy frequently results in treatment failure, highlighting the need to identify novel therapeutic targets to improve clinical outcomes.

METHODS

The expression of molecule interacting with CasL-2 (MICAL2) was confirmed in cervical cancer tissues and cell lines through western blotting (WB) and immunohistochemistry (IHC). Siha and Hela cells were used to examine the regulatory and biological functions of MICAL2 via knockdown and overexpression experiments. Assays including MTT, colony formation, wound healing, transwell migration, and sphere formation were employed, along with WB analysis. DNA damage in irradiated cells with MICAL2 knockdown or overexpression was evaluated using the comet assay, while γ-H2AX and Rad51 protein levels were detected by WB. In vivo experiments validated the tumorigenic and radioresistance functions of MICAL2. Additionally, the relationship between MICAL2 expression and radiotherapy response was analyzed in 62 patients with cervical cancer by assessing tumor regression and MICAL2 levels six months post-treatment.

RESULTS

MICAL2 expression was significantly elevated in cervical cancer tissues and cells. Functional analyses demonstrated that MICAL2 promotes cell proliferation, migration, and invasion by activating the MAPK and PI3K/AKT pathways, as confirmed through both in vitro and in vivo experiments. Silencing MICAL2 increased DNA damage, impeded DNA repair, and enhanced radiosensitivity. Among the 62 patients with cervical cancer, elevated MICAL2 expression was associated with a lower complete response rate to radiotherapy (25.6% vs. 60.9% in those with low expression), reduced progression-free survival, and advanced cancer stage (*p < 0.05).

CONCLUSION

MICAL2 plays a critical role in tumor progression and radiotherapy resistance in cervical cancer. These findings provide a foundation for developing targeted therapies to improve treatment outcomes in this population.

Genetic and epigenetic characterization of sarcoma stem cells across subtypes identifies EZH2 as a therapeutic target

High-grade soft tissue sarcomas (STS) are a heterogeneous and aggressive set of cancers. Failure to respond anthracycline chemotherapy, standard first-line treatment, is associated with poor outcomes. We investigated the contribution of STS cancer stem cells (STS-CSCs) to doxorubicin resistance. We identified a positive correlation between CSC abundance and doxorubicin IC50. Utilizing patient-derived samples from five sarcoma subtypes we investigated if a common genetic signature across STS-CSCs could be targeted. We identified Enhancer of Zeste homolog 2 (EZH2), a member of the polycomb repressive complex 2 (PRC2) responsible for H3K27 methylation as being enriched in CSCs. EZH2 activity and a shared epigenetic profile was observed across subtypes and targeting of EZH2 ablated the STS-CSC population. Treatment of doxorubicin-resistant cell lines with tazemetostat resulted in a decrease in the STS-CSC population. These data confirm the presence of shared genetic programs across distinct subtypes of CSC-STS that can be therapeutically targeted.

Characterization of stem cell landscape and identification of stemness-relevant prognostic gene signature to aid immunotherapy in breast cancer

A common digestive system cancer with a dismal prognosis and a high death rate globally is breast cancer (BRCA). BRCA recurrence, metastasis, and medication resistance are all significantly impacted by cancer stem cells (CSCs). However, the relationship between CSCs and the tumor microenvironment in BRCA individuals remains unknown, and this information is critically needed. Our research utilized bioinformatics techniques and TCGA data to explore the complex relationship between CSCs and BRCA development. We identified 26 stem cell gene sets from the Stem Checker database and classified BRCA samples into stemness subtypes using consensus clustering. Prognosis, tumor microenvironment (TME) elements, and treatment responses varied across subtypes. Using LASSO, Cox regression, and differential expression analysis, we developed a stemness-risk model. BRCA patients were divided into two groups (Cluster A and Cluster B). Cluster B exhibited an improved prognosis, higher PIK3CA mutation frequency, and increased levels of CD8 T cells and regulatory Tregs. A 5-gene stemness model was constructed, showing that higher stemness scores correlated with poorer prognosis. The model was validated using the METABRIC cohort data from cBioPortal. Our findings identify two stemness-related subgroups with distinct prognoses and TME patterns. Further experimental validation is necessary before this model can be considered for clinical application.

Prediction of bladder cancer prognosis and immune microenvironment assessment using machine learning and deep learning models

Bladder cancer (BCa) is a heterogeneous malignancy characterized by distinct immune subtypes, primarily due to differences in tumor-infiltrating immune cells and their functional characteristics. Therefore, understanding the tumor immune microenvironment (TIME) landscape in BCa is crucial for prognostic prediction and guiding precision therapy. In this study, we integrated 10 machine learning algorithms to develop an immune-related machine learning signature (IRMLS) and subsequently created a deep learning model to detect the IRMLS subtype based on pathological images. The IRMLS proved to be an independent prognostic factor for overall survival (OS) and demonstrated robust and stable performance (p < 0.01). The high-risk group exhibited an immune-inflamed phenotype, associated with poorer prognosis and higher levels of immune cell infiltration. We further investigated the cancer immune cycle and mutation landscape within the IRMLS model, confirming that the high-risk group is more sensitive to immune checkpoint immunotherapy (ICI) and adjuvant chemotherapy with cisplatin (p = 2.8e-10), docetaxel (p = 8.8e-13), etoposide (p = 1.8e-07), and paclitaxel (p = 6.2e-13). In conclusion, we identified and validated a machine learning-based molecular characteristic, IRMLS, which reflects various aspects of the BCa biological process and offers new insights into personalized precision therapy for BCa patients.

Phosphorylation-mediated disassembly of C-terminal binding protein 2 tetramer impedes epigenetic silencing of pluripotency in mouse embryonic stem cells

Cells need to overcome both intrinsic and extrinsic threats. Although pluripotency is associated with damage responses, how stem cells respond to DNA damage remains controversial. Here, we elucidate that DNA damage activates Chk2, leading to the phosphorylation of serine 164 on C-terminal binding protein 2 (Ctbp2). The phosphorylation of Ctbp2 induces the disruption of Ctbp2 tetramer, weakening interactions with zinc finger proteins, leading to the dissociation of phosphorylated Ctbp2 from chromatin. This transition to a monomeric state results in the separation of histone deacetylase 1 from Ctbp2, consequently slowing the rate of H3K27 deacetylation. In contrast to the nucleosome remodeling and deacetylase complex, phosphorylated Ctbp2 increased binding affinity to polycomb repressive complex (PRC)2, interacting through the N-terminal domain of Suz12. Through this domain, Ctbp2 competes with Jarid2, inhibiting the function of PRC2. Thus, the phosphorylation of Ctbp2 under stress conditions represents a precise mechanism aimed at preserving stemness traits by inhibiting permanent transcriptional shutdown.

Multifaceted impact of HIV inhibitor dapivirine on triple negative breast cancer cells reveals potential entities as targets for novel therapy

Breast cancer is the most common cancer in women worldwide. Many breast cancers originate from the cells lining the milk duct and some become invasive. Breast cancer lacking estrogen, progesterone receptors (ER-, PR-) and epidermal growth factor receptor 2 (HER2-) amplification, termed "Triple negative" (TNBC) is reported to frequently affect Black women and younger women. TNBC is an invasive ductal carcinoma with limited treatment options. To this end, we opted to investigate drugs that could be repurposed because they offer advantages in bringing effective treatments faster to the clinic. We chose to study the effect of the drug, dapivirine, a non-nucleoside reverse transcriptase inhibitor (NNRTI) of HIV because it could be detected in the breast milk of lactating women when treated for HIV and the drug could potentially target the cancer. Here we show the potent impact of dapivirine on MDA-MB-231 TNBC cells, while NNRTI like nevirapine showed marginal effects. When dapivirine was tested on other breast cell lines, MCF-7 and MCF 10A, the inhibition was at higher concentrations. Molecular studies with dapivirine in TNBC cells, revealed an increase in reactive oxygen species (ROS), apoptotic cells, and activation of caspases. Importantly, protein profiling and STRING analysis revealed deregulation of the key molecule, PCNA and impact on pivotal cell signaling circuits including extracellular matrix (ECM), angiogenesis, cell adhesion, and immunomodulation. Of note, is its potential effect on stem-like cells due to downregulation of the basic transcription factor 3 (BTF3) and proteasome activator complex subunit 3; the latter affecting their dependence on the proteasome pathway. Taken together, dapivirine exhibits the potential to be considered as a repurposed drug for TNBC as monotherapy/combination therapy. Notably, it could also potentially be a treatment for individuals with dual ailments, such as HIV and TNBC, if the clinical outcomes with dapivirine for TNBC become favorable.

Ovatodiolide inhibits endometrial cancer stemness via reactive oxygen species-mediated DNA damage and cell cycle arrest

Endometrial cancer (EC) is a common gynecological cancer worldwide, often associated with a poor prognosis after recurrence or metastasis. Ovatodiolide (OVA) is a macrocyclic diterpenoid derived from Anisomeles indica that shows anticancer effects in various malignancies. This study aimed to evaluate the cytotoxic effects of OVA on EC cell proliferation and cancer stem cell (CSC) activity and explore its underlying molecular mechanisms. OVA treatment dose-dependently reduced the viability and colony formation of three EC cell lines (AN3CA, HEC-1A, and EMC6). It induced G2/M phase cell cycle arrest, associated with decreased cell division cycle 25C (CDC25C) expression and reduced activation of cyclin-dependent kinases 1 (CDK1) and 2 (CDK2). OVA also increased reactive oxygen species (ROS) production and DNA damage, activating the DNA damage-sensitive cell cycle checkpoint kinases 1 (CHK1) and 2 (CHK2) and upregulating the DNA damage marker γ-H2A.X variant histone (H2AX). It also suppressed the activation of mechanistic target of rapamycin kinase (mTOR) and nuclear factor kappa B (NF-κB) and downregulated glutathione peroxidase 1 (GPX1), an antioxidant enzyme counteracting oxidative stress. Moreover, OVA reduced the self-renewal capacity of CSCs, reducing the expression of key stemness proteins Nanog homeobox (NANOG) and octamer-binding transcription factor 4 (OCT4). The ROS inhibitor N-acetylcysteine attenuated the anti-proliferative and anti-CSC effects of OVA. Our findings suggest that OVA acts via ROS generation, leading to oxidative stress and DNA damage, culminating in cell cycle arrest and the suppression of CSC activity in EC. Therefore, OVA is a promising therapeutic agent for EC, either as a standalone treatment or an adjunct to existing therapies.

Cancer Stem Cell markers: Symphonic masters of chemoresistance and immune evasion

Cancer Stem Cells (CSCs) are highly tumorigenic, chemoresistant, and immune evasive. They emerge as a central driver that gives rise to the bulk of tumoral mass, modifies the tumor microenvironment (TME), and exploits it, leading to poor clinical outcomes for patients with cancer. The existence of CSCs thus accounts for the failure of conventional therapies and immune surveillance. Identifying CSCs in solid tumors remains a significant challenge in modern oncology, with the use of cell surface markers being the primary strategy for studying, isolating, and enriching these cells. In this review, we explore CSC markers, focusing on the underlying signaling pathways that drive CSC self-renewal, which simultaneously makes them intrinsically chemoresistant and immune system evaders. We comprehensively discuss the autonomous and non-autonomous functions of CSCs, with particular emphasis on their interactions with the tumor microenvironment, especially immune cells. This reciprocal network enhances CSCs malignancy while compromising the surrounding niche, ultimately defining therapeutic vulnerabilities associated with each CSC marker. The most common CSCs surface markers addressed in this review-CD44, CD133, ICAM1/CD54, and LGR5-provide insights into the interplay between chemoresistance and immune evasion, two critically important phenomena in disease eradication. This new perspective on the state-of-the-art of CSCs will undoubtedly open new avenues for therapy.

Novel PROTAC probes targeting FOSL1 degradation to eliminate head and neck squamous cell carcinoma cancer stem cells

Previously, we identified that AP-1 transcription factor FOSL1 is required to maintain cancer stem cells (CSCs) in HNSCC, and an AP-1 inhibitor, T-5224, can eliminate HNSCC CSCs. However, its potency is relatively low, and furthermore, whether T-5224 eradicates CSCs through targeting FOSL1 and whether FOSL1 serves as an effective target for eliminating CSCs in HNSCC, require further validation. We first found that T-5224 can bind to FOSL1 directly. As a proof-of-principle, several cereblon (CRBN)-recruiting PROTACs were designed and synthesized using T-5224 as a warhead for more effective of targeting FOSL1. The top compound can potently degrade FOSL1 in HNSCC, thereby effectively eliminating CSCs to suppress HNSCC tumorigenesis, with around 30 to 100-fold improved potency over T-5224. In summary, our study further validates FOSL1 as an effective target for eliminating CSCs in HNSCC and suggests that PROTACs may provide a unique molecular tool for the development of novel molecules for targeting FOSL1.

Cancer Stem Cells in Oral Squamous Cell Carcinoma: A Narrative Review on Experimental Characteristics and Methodological Challenges

Cancer stem cells (CSCs) represent a subpopulation of cancer cells that are believed to initiate and drive cancer progression. In animal models, xenotransplanted CSCs have demonstrated the ability to produce tumors. Since their initial isolation in blood cancers, CSCs have been identified in various solid human cancers, including oral squamous cell carcinoma (OSCC). In addition to their tumorigenic properties, dysregulated stem-cell-related signaling pathways-Wnt family member (Wnt), neurogenic locus notch homolog protein (Notch), and hedgehog-have been shown to endow CSCs with characteristics like self-renewal, phenotypic plasticity, and chemoresistance, contributing to recurrence and treatment failure. Consequently, CSCs have become targets for new therapeutic agents, with some currently in different phases of clinical trials. Notably, small molecule inhibitors of the hedgehog signaling pathway, such as vismodegib and glasdegib, have been approved for the treatment of basal cell carcinoma and acute myeloid leukemia, respectively. Other strategies for eradicating CSCs include natural compounds, nano-drug delivery systems, targeting mitochondria and the CSC microenvironment, autophagy, hyperthermia, and immunotherapy. Despite the extensive documentation of CSCs in OSCC since its first demonstration in head and neck (HN) SCC in 2007, none of these novel pharmacological approaches have yet entered clinical trials for OSCC patients. This narrative review summarizes the in vivo and in vitro evidence of CSCs and CSC-related signaling pathways in OSCC, highlighting their role in promoting chemoresistance and immunotherapy resistance. Additionally, it addresses methodological challenges and discusses future research directions to improve experimental systems and advance CSC studies.

VDAC1-Based Peptides as Potential Modulators of VDAC1 Interactions with Its Partners and as a Therapeutic for Cancer, NASH, and Diabetes

This review presents current knowledge related to the voltage-dependent anion channel-1 (VDAC1) as a multi-functional mitochondrial protein that acts in regulating both cell life and death. The location of VDAC1 at the outer mitochondrial membrane (OMM) allows control of metabolic cross-talk between the mitochondria and the rest of the cell, and also enables its interaction with proteins that are involved in metabolic, cell death, and survival pathways. VDAC1's interactions with over 150 proteins can mediate and regulate the integration of mitochondrial functions with cellular activities. To target these protein-protein interactions, VDAC1-derived peptides have been developed. This review focuses specifically on cell-penetrating VDAC1-based peptides that were developed and used as a "decoy" to compete with VDAC1 for its VDAC1-interacting proteins. These peptides interfere with VDAC1 interactions, for example, with metabolism-associated proteins such as hexokinase (HK), or with anti-apoptotic proteins such as Bcl-2 and Bcl-xL. These and other VDAC1-interacting proteins are highly expressed in many cancers. The VDAC1-based peptides in cells in culture selectively affect cancerous, but not non-cancerous cells, inducing cell death in a variety of cancers, regardless of the cancer origin or genetics. They inhibit cell energy production, eliminate cancer stem cells, and act very rapidly and at low micro-molar concentrations. The activity of these peptides has been validated in several mouse cancer models of glioblastoma, lung, and breast cancers. Their anti-cancer activity involves a multi-pronged attack targeting the hallmarks of cancer. They were also found to be effective in treating non-alcoholic fatty liver disease and diabetes mellitus. Thus, VDAC1-based peptides, by targeting VDAC1-interacting proteins, offer an affordable and innovative new conceptual therapeutic paradigm that can potentially overcome heterogeneity, chemoresistance, and invasive metastatic formation.

Epigenetic modification of ferroptosis by non-coding RNAs in cancer drug resistance

The development of drug resistance remains a major challenge in cancer treatment. Ferroptosis, a unique type of regulated cell death, plays a pivotal role in inhibiting tumour growth, presenting new opportunities in treating chemotherapeutic resistance. Accumulating studies indicate that epigenetic modifications by non-coding RNAs (ncRNA) can determine cancer cell vulnerability to ferroptosis. In this review, we first summarize the role of chemotherapeutic resistance in cancer growth/development. Then, we summarize the core molecular mechanisms of ferroptosis, its upstream epigenetic regulation, and its downstream effects on chemotherapeutic resistance. Finally, we review recent advances in understanding how ncRNAs regulate ferroptosis and from such modulate chemotherapeutic resistance. This review aims to enhance general understanding of the ncRNA-mediated epigenetic regulatory mechanisms which modulate ferroptosis, highlighting the ncRNA-ferroptosis axis as a key druggable target in overcoming chemotherapeutic resistance.

Competing endogenous RNAs regulatory crosstalk networks: The messages from the RNA world to signaling pathways directing cancer stem cell development

Cancer stem cells (CSCs) are one of the cell types that account for cancer heterogeneity. The cancer cells arrest in G0 and generate non-CSC progeny through self-renewal and pluripotency, resulting in tumor recurrence, metastasis, and resistance to chemotherapy. They can stimulate tumor relapse and re-grow a metastatic tumor. So, CSCs is a promising target for eradicating tumors, and developing an anti-CSCs therapy has been considered. In recent years competing endogenous RNA (ceRNA) has emerged as a significant class of post-transcriptional regulators that affect gene expression via competition for microRNA (miRNA) binding. Furthermore, aberrant ceRNA expression is associated with tumor progression. Recent findings show that ceRNA network can cause tumor progression through the effect on CSCs. To overcome therapeutic resistance due to CSCs, we need to improve our current understanding of the mechanisms by which ceRNAs are implicated in CSC-related relapse. Thus, this review was designed to discuss the role of ceRNAs in CSCs' function. Targeting ceRNAs may open the path for new cancer therapeutic targets and can be used in clinical research.

The YTH domain-containing protein family: Emerging players in immunomodulation and tumour immunotherapy targets

BACKGROUND

The modification of N6-methyladenosine (m6A) plays a pivotal role in tumor by altering both innate and adaptive immune systems through various pathways, including the regulation of messenger RNA. The YTH domain protein family, acting as "readers" of m6A modifications, affects RNA splicing, stability, and immunogenicity, thereby playing essential roles in immune regulation and antitumor immunity. Despite their significance, the impact of the YTH domain protein family on tumor initiation and progression, as well as their involvement in tumor immune regulation and therapy, remains underexplored and lacks comprehensive review.

CONCLUSION

This review introduces the molecular characteristics of the YTH domain protein family and their physiological and pathological roles in biological behavior, emphasizing their mechanisms in regulating immune responses and antitumor immunity. Additionally, the review discusses the roles of the YTH domain protein family in immune-related diseases and tumor resistance, highlighting that abnormal expression or dysfunction of YTH proteins is closely linked to tumor resistance.

KEY POINTS

This review provides an in-depth understanding of the YTH domain protein family in immune regulation and antitumor immunity, suggesting new strategies and directions for immunotherapy of related diseases. These insights not only deepen our comprehension of m6A modifications and YTH protein functions but also pave the way for future research and clinical applications.

Plant natural compounds in the cancer treatment: A systematic bibliometric analysis

Plant-derived natural compounds are significant resources for the discovery of potential anticancer drugs. While research in the plant-based anticancer field has surged in recent years, systematic bibliometric analyses covering a longer period and containing up-to-date publications remain scarce. Here, we conducted a bibliometric analysis of literature on the anticancer properties of plant natural compounds over the past three decades, leveraging the bibliometric framework and open-access platform, KNIME. Our findings showed that the number of plant anticancer-related publications underwent an accelerating growth from 1992 to 2023. The country and institution analyses revealed that countries with traditional medical systems contributed a large portion of publications in the plant anticancer field, such as India, China, and South Korea. This study also highlighted the top ten eminent researchers and publications, assisting researchers in identifying pivotal literature. The primary publications were domains of chemistry and biology-related fields, such as Pharmacology & Pharmacy, Plant Sciences, and Biochemistry & Molecular Biology. Additionally, we noted that flavonoids have been focal plant compounds in anticancer, with strong anticancer potential. Our study provides new insights into the progress and trends in the plant anticancer field and will assist researchers in grasping the future research direction.

STAU1-mediated CNBP mRNA degradation by LINC00665 alters stem cell characteristics in ovarian cancer

BACKGROUND

To investigate the role of lncRNA LINC00665 in modulating ovarian cancer stemness and its influence on treatment resistance and cancer development.

METHODS

We isolated ovarian cancer stem cells (OCSCs) from the COC1 cell line using a combination of chemotherapeutic agents and growth factors, and verified their stemness through western blotting and immunofluorescence for stem cell markers. Employing bioinformatics, we identified lncRNAs associated with ovarian cancer, with a focus on LINC00665 and its interaction with the CNBP mRNA. In situ hybridization, immunohistochemistry, and qPCR were utilized to examine their expression and localization, alongside functional assays to determine the effects of LINC00665 on CNBP.

RESULTS

LINC00665 employs its Alu elements to interact with the 3'-UTR of CNBP mRNA, targeting it for degradation. This molecular crosstalk enhances stemness by promoting the STAU1-mediated decay of CNBP mRNA, thereby modulating the Wnt and Notch signaling cascades that are pivotal for maintaining CSC characteristics and driving tumor progression. These mechanistic insights were corroborated by a series of in vitro assays and validated in vivo using tumor xenograft models. Furthermore, we established a positive correlation between elevated CNBP levels and increased disease-free survival in patients with ovarian cancer, underscoring the prognostic value of CNBP in this context.

CONCLUSIONS

lncRNA LINC00665 enhances stemness in ovarian cancer by mediating the degradation of CNBP mRNA, thereby identifying LINC00665 as a potential therapeutic target to counteract drug resistance and tumor recurrence associated with CSCs.

Cancer-associated fibroblasts and prostate cancer stem cells: crosstalk mechanisms and implications for disease progression

The functional heterogeneity and ecological niche of prostate cancer stem cells (PCSCs), which are major drivers of prostate cancer development and treatment resistance, have attracted considerable research attention. Cancer-associated fibroblasts (CAFs), which are crucial components of the tumor microenvironment (TME), substantially affect PCSC stemness. Additionally, CAFs promote PCSC growth and survival by releasing signaling molecules and modifying the surrounding environment. Conversely, PCSCs may affect the characteristics and behavior of CAFs by producing various molecules. This crosstalk mechanism is potentially crucial for prostate cancer progression and the development of treatment resistance. Using organoids to model the TME enables an in-depth study of CAF-PCSC interactions, providing a valuable preclinical tool to accurately evaluate potential target genes and design novel treatment strategies for prostate cancer. The objective of this review is to discuss the current research on the multilevel and multitarget regulatory mechanisms underlying CAF-PCSC interactions and crosstalk, aiming to inform therapeutic approaches that address challenges in prostate cancer treatment.

CYR61 confers chemoresistance by upregulating survivin expression in triple-negative breast cancer

Cysteine-rich angiogenic inducer 61 (CYR61) is a protein from the CCN family of matricellular proteins that play diverse regulatory roles in the extracellular matrix. CYR61 is involved in cell adhesion, migration, proliferation, differentiation, apoptosis, and senescence. Here, we show that CYR61 induces chemoresistance in triple-negative breast cancer (TNBC). We observed that CYR61 is overexpressed in TNBC patients, and CYR61 expression correlates negatively with the survival of patients who receive chemotherapy. CYR61 knockdown reduced cell migration, sphere formation and the cancer stem cell (CSC) population and increased the chemosensitivity of TNBC cells. Mechanistically, CYR61 activated Wnt/β-catenin signaling and increased survivin expression, which are associated with chemoresistance, the epithelial-mesenchymal transition, and CSC-like phenotypes. Altogether, our study demonstrates a novel function of CYR61 in chemotherapy resistance in breast cancer.

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Genetic and Epigenetic Characterization of Sarcoma Stem Cells Across Subtypes Identifies EZH2 as a Therapeutic Target

High-grade complex karyotype soft tissue sarcomas (STS) are a heterogeneous and aggressive set of cancers that share a common treatment strategy. Disease progression and failure to respond to anthracycline based chemotherapy, standard first-line treatment, is associated with poor patient outcomes. To address this, we investigated the contribution of STS cancer stem cells (STS-CSCs) to doxorubicin resistance. We identified a positive correlation between CSC abundance and doxorubicin IC 50 in resistant cell lines. We investigated if a common genetic signature across STS-CSCs could be targeted. Utilizing patient derived samples from five sarcoma subtypes we identified Enhancer of Zeste homolog 2 (EZH2), a member of the polycomb repressive complex 2 (PRC2) responsible for H3K27 methylation as being enriched in the CSC population. EZH2 activity and a shared epigenetic profile was observed across subtypes. Targeting of EZH2 using Tazemetostat, an FDA approved inhibitor specifically ablated the STS-CSC population. Treatment of doxorubicin resistant cell lines with tazemetostat resulted in a decrease in the STS-CSC population. Further, co-treatment was not only synergistic in the parent cell lines, but restored chemosensitivity in doxorubicin resistant lines. These data confirm the presence of shared genetic programs across distinct subtypes of CSC-STS that can be therapeutically targeted.

The intricate interplay between cancer stem cells and cell-of-origin of cancer: implications for therapeutic strategies

Background

Cancer stem cells (CSCs) have emerged as pivotal players in tumorigenesis, disease progression, and resistance to therapies.

Objective

This comprehensive review delves into the intricate relationship between CSCs and the cell-of-origin in diverse cancer types.

Design

Comprehensive review of thematically-relevant literature.

Methods

We explore the underlying molecular mechanisms that drive the conversion of normal cells into CSCs and the impact of the cell-of-origin on CSC properties, tumor initiation, and therapeutic responses. Moreover, we discuss potential therapeutic interventions targeting CSCs based on their distinct cell-of-origin characteristics.

Results

Accruing evidence suggest that the cell-of-origin, the cell type from which the tumor originates, plays a crucial role in determining the properties of CSCs and their contribution to tumor heterogeneity.

Conclusion

By providing critical insights into the complex interplay between CSCs and their cellular origins, this article aims to enhance our understanding of cancer biology and pave the way for more effective and personalized cancer treatments.

In silico identification and in vitro validation of alpha-hederin as a potent inhibitor of Wnt/β-catenin signaling pathway in breast cancer stem cells

Cancer stem cells (CSCs) play a vital role in metastasis, recurrence and chemoresistance in breast cancer. β-catenin, which is a frequently over activated protein in CSCs, binds to T-cell factor/lymphoid enhancer factor (Tcf/Lef) family transcription factors leading to ectopic expression of Wnt pathway responsive genes necessary for the maintenance and action of CSCs. With the aim of identifying a small molecules that can effectively eliminate CSCs, molecular docking studies were performed against the Tcf/Lef binding hotspot on β-catenin using a library of 100 natural or synthetic small molecules. Small molecule ligands giving docking energy better than - 7 kcal/mol were further investigated by binding interactions analysis and molecular dynamics (MD) simulations. These compounds were then investigated in vitro, for cytotoxicity against CSCs isolated from MDA-MB-231 triple negative breast cancer cells. Alpha-hederin (AH) was identified as the only compound in the selected library that has cytotoxicity against breast CSCs. AH was further investigated for it's ability to regulate Wnt pathway target genes (Cyclin D1 and CD44)and the tumor suppressor p53by real-time quantitative PCR. Absorption, distribution, metabolism, excretion and toxicity properties of the AH was predicted in silico. AH significantly down regulated the transcription of Cyclin D1 and CD44 while up-regulating the transcription of p53. AH was predicted to have acceptable drug likeness. Although AH is currently known to inhibit the growth of various cancer cells in vitro, present study demonstrated for the first time that it is a potent inhibitor of Wnt/β-catenin signaling pathway and induce apoptosis in breast CSCs.

The research progress on radiation resistance of cervical cancer

Cervical carcinoma is the most prevalent gynecology malignant tumor and ranks as the fourth most common cancer worldwide, thus posing a significant threat to the lives and health of women. Advanced and early-stage cervical carcinoma patients with high-risk factors require adjuvant treatment following surgery, with radiotherapy being the primary approach. However, the tolerance of cervical cancer to radiotherapy has become a major obstacle in its treatment. Recent studies have demonstrated that radiation resistance in cervical cancer is closely associated with DNA damage repair pathways, the tumor microenvironment, tumor stem cells, hypoxia, cell cycle arrest, and epigenetic mechanisms, among other factors. The development of tumor radiation resistance involves complex interactions between multiple genes, pathways, and mechanisms, wherein each factor interacts through one or more signaling pathways. This paper provides an overview of research progress on an understanding of the mechanism underlying radiation resistance in cervical cancer.

Silencing the Mitochondrial Gatekeeper VDAC1 as a Potential Treatment for Bladder Cancer

The strategy for treating bladder cancer (BC) depends on whether there is muscle invasion or not, with the latter mostly treated with intravesical therapy, such as with bacillus Calmette-Guérin (BCG). However, BCG treatment is unsuccessful in 70% of patients, who are then subjected to radical cystectomy. Although immune-checkpoint inhibitors have been approved as a second-line therapy for a subset of BC patients, these have failed to meet primary endpoints in clinical trials. Thus, it is crucial to find a new treatment. The mitochondrial gatekeeper protein, the voltage-dependent anion channel 1 (VDAC1), mediates metabolic crosstalk between the mitochondria and cytosol and is involved in apoptosis. It is overexpressed in many cancer types, as shown here for BC, pointing to its significance in high-energy-demanding cancer cells. The BC cell lines UM-UC3 and HTB-5 express high VDAC1 levels compared to other cancer cell lines. VDAC1 silencing in these cells using siRNA that recognizes both human and mouse VDAC1 (si-m/hVDAC1-B) reduces cell viability, mitochondria membrane potential, and cellular ATP levels. Here, we used two BC mouse models: subcutaneous UM-UC3 cells and chemically induced BC using the carcinogen N-Butyl-N-(4-hydroxybutyl) nitrosamine (BBN). Subcutaneous UM-UC3-derived tumors treated with si-m/hVDAC1 showed inhibited tumor growth and reprogrammed metabolism, as reflected in the reduced expression of metabolism-related proteins, including Glut1, hexokinase, citrate synthase, complex-IV, and ATP synthase, suggesting reduced metabolic activity. Furthermore, si-m/hVDAC1-B reduced the expression levels of cancer-stem-cell-related proteins (cytokeratin-14, ALDH1a), modifying the tumor microenvironment, including decreased angiogenesis, extracellular matrix, tumor-associated macrophages, and inhibited epithelial-mesenchymal transition. The BBN-induced BC mouse model showed a clear carcinoma, with damaged bladder morphology and muscle-invasive tumors. Treatment with si-m/hVDAC1-B encapsulated in PLGA-PEI nanoparticles that were administered intravesically directly to the bladder showed a decreased tumor area and less bladder morphology destruction and muscle invasion. Overall, the obtained results point to the potential of si-m/hVDAC1-B as a possible therapeutic tool for treating bladder cancer.

N6-methyladenosine (m6A) modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the deadliest cancers of human, the tumor-related death of which ranks third among the common malignances. N6-methyladenosine (m6A) methylation, the most abundant internal modification of RNA in mammals, participates in the metabolism of mRNA and interrelates with ncRNAs. In this paper, we overviewed the complex function of m6A regulators in HCC, including regulating the tumorigenesis, progression, prognosis, stemness, metabolic reprogramming, autophagy, ferroptosis, drug resistance and tumor immune microenvironment (TIME). Furthermore, we elucidated the interplay between m6A modification and non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). Finally, we summarized the potential of m6A regulators as diagnostic biomarkers. What's more, we reviewed the inhibitors targeting m6A enzymes as promising therapeutic targets of HCC. We aimed to help understand the function of m6A methylation in HCC systematically and comprehensively so that more effective strategies for HCC treatment will be developed.

Inhibition of MEK Signaling Attenuates Cancer Stem Cell Activity in Anaplastic Thyroid Cancer

Background: Anaplastic thyroid cancer (ATC) is highly aggressive and has very limited treatment options. Recent studies suggest that cancer stem cell (CSC) activity in ATC could underlie this recurrence and resistance to treatment. The recent approval by the U.S. Food and Drug Administration of the combined treatment of BRAF and MEK inhibitors for ATC patients has shown some efficacy in patients harboring the BRAFV600E mutation. However, it was unknown whether the combined treatment could affect the CSC activity. This study explores the effects of the BRAF and MEK inhibitors on CSC activity in human ATC cells. Methods: Using three human ATC cells, THJ-11T, THJ-16T, and 8505C cells, we evaluated the effects of dabrafenib (a BRAF kinase inhibitor), trametinib (an MEK inhibitor), or a combined treatment of the two drugs on the CSC activity by tumorsphere formation, Aldefluor assays, expression profiles of key CSC markers, immunohistochemistry, and in vivo xenograft mouse models. Furthermore, we also used confocal imaging to directly visualize the effects on drugs on CSCs by the SORE6-mCherry reporter in cultured cells and xenograft tumor cells. Results: The BRAF inhibitor, dabrafenib, had weak efficacy, while the MEK inhibitor, trametinib, showed strong efficacy in attenuating the CSC activity, as evidenced by suppression of CSC marker expression, tumorsphere formation, and Aldefluor assays. Using ATC cells expressing a fluorescent CSC SORE6 reporter, we showed reduction of CSC activity in the rank order of combined > trametinib > dabrafenib through in vitro and in vivo xenograft models. Molecular analyses showed that suppression of CSC activity by these drugs was, in part, mediated by attenuation of the transcription by dampening the RNA polymerase II activity. Conclusions: Our analyses demonstrated the presence of CSCs in ATC cells. The inhibition of CSC activity by the MEK signaling could partially account for the efficacy of the combined treatment shown in ATC patients. However, our studies also showed that not all CSC activity was totally abolished, which may account for the recurrence observed in ATC patients. Our findings have provided new insights into the molecular basis of efficacy and limitations of these drugs in ATC patients.

Modelling the complex nature of the tumor microenvironment: 3D tumor spheroids as an evolving tool

Cancer remains a serious burden in society and while the pace in the development of novel and more effective therapeutics is increasing, testing platforms that faithfully mimic the tumor microenvironment are lacking. With a clear shift from animal models to more complex in vitro 3D systems, spheroids emerge as strong options in this regard. Years of development have allowed spheroid-based models to better reproduce the biomechanical cues that are observed in the tumor-associated extracellular matrix (ECM) and cellular interactions that occur in both a cell-cell and cell-ECM manner. Here, we summarize some of the key cellular interactions that drive tumor development, progression and invasion, and how successfully are these interactions recapitulated in 3D spheroid models currently in use in the field. We finish by speculating on future advancements in the field and on how these can shape the relevance of spherical 3D models for tumor modelling.

Cancer cell cycle heterogeneity as a critical determinant of therapeutic resistance

Intra-tumor heterogeneity is now arguably one of the most-studied topics in tumor biology, as it represents a major obstacle to effective cancer treatment. Since tumor cells are highly diverse at genetic, epigenetic, and phenotypic levels, intra-tumor heterogeneity can be assumed as an important contributing factor to the nullification of chemotherapeutic effects, and recurrence of the tumor. Based on the role of heterogeneous subpopulations of cancer cells with varying cell-cycle dynamics and behavior during cancer progression and treatment; herein, we aim to establish a comprehensive definition for adaptation of neoplastic cells against therapy. We discuss two parallel and yet distinct subpopulations of tumor cells that play pivotal roles in reducing the effects of chemotherapy: "resistant" and "tolerant" populations. Furthermore, this review also highlights the impact of the quiescent phase of the cell cycle as a survival mechanism for cancer cells. Beyond understanding the mechanisms underlying the quiescence, it provides an insightful perspective on cancer stem cells (CSCs) and their dual and intertwined functions based on their cell cycle state in response to treatment. Moreover, CSCs, epithelial-mesenchymal transformed cells, circulating tumor cells (CTCs), and disseminated tumor cells (DTCs), which are mostly in a quiescent state of the cell cycle are proved to have multiple biological links and can be implicated in our viewpoint of cell cycle heterogeneity in tumors. Overall, increasing our knowledge of cell cycle heterogeneity is a key to identifying new therapeutic solutions, and this emerging concept may provide us with new opportunities to prevent the dreadful cancer recurrence.

Immunization with Embryonic Stem Cells/Induced Pluripotent Stem Cells Induces Effective Immunity against Ovarian Tumor-Initiating Cells in Mice

Cancer stem cells (CSCs) express pluripotent markers and share many features with normal pluripotent stem cells. It is possible that immunity induced by embryonic stem cells (ESCs) and induced pluripotent stem cells- (IPSCs-) based vaccines may selectively target CSCs. In our study, cells expressing the pluripotent marker CD133 in the murine ovarian cancer cell-line ID8 were isolated and identified as CSCs. We investigated the preventive efficacy of ESCs and IPSCs-based vaccines against the development of ovarian cancer in vivo and evaluated the humoral and cellular immunities targeting CSCs in vitro. Our study showed that preimmunization with both mouse-derived embryonic stem cells (mESCs) and mouse-induced pluripotent stem cells (mIPSCs) lysates, combined with an immunostimulatory adjuvant CpG, elicited strong humoral and cellular responses. These responses effectively suppressed the development of CSC-derived tumors. Immune sera collected from mESCs and mIPSCs-vaccinated mice contained antibodies that were capable of selectively targeting CSCs, resulting in the lysis of CSCs in the presence of complement. Cytotoxic T-lymphocytes generated from splenocytes of mESCs and mIPSCs-vaccinated hosts could secrete interferon- (IFN-) γ in response to CSCs and kill CSCs in vitro. These findings indicate that vaccines based on mESCs and mIPSCs can elicit effective antitumor immunities. These immunities are related to the conferring of humoral and cellular responses that directly target CSCs.

Drug-tolerant persister cells in cancer: the cutting edges and future directions

Drug-tolerant persister (DTP) cell populations were originally discovered in antibiotic-resistant bacterial biofilms. Similar populations with comparable features have since been identified among cancer cells and have been linked with treatment resistance that lacks an underlying genomic alteration. Research over the past decade has improved our understanding of the biological roles of DTP cells in cancer, although clinical knowledge of the role of these cells in treatment resistance remains limited. Nonetheless, targeting this population is anticipated to provide new treatment opportunities. In this Perspective, we aim to provide a clear definition of the DTP phenotype, discuss the underlying characteristics of these cells, their biomarkers and vulnerabilities, and encourage further research on DTP cells that might improve our understanding and enable the development of more effective anticancer therapies.

Bladder cancer: therapeutic challenges and role of 3D cell culture systems in the screening of novel cancer therapeutics

Bladder cancer (BC) is the sixth most common worldwide urologic malignancy associated with elevated morbidity and mortality rates if not well treated. The muscle-invasive form of BC develops in about 25% of patients. Moreover, according to estimates, 50% of patients with invasive BC experience fatal metastatic relapses. Currently, resistance to drug-based therapy is the major tumble to BC treatment. The three-dimensional (3D) cell cultures are clearly more relevant not only as a novel evolving gadget in drug screening but also as a bearable therapeutic for different diseases. In this review, various subtypes of BC and mechanisms of drug resistance to the commonly used anticancer therapies are discussed. We also summarize the key lineaments of the latest cell-based assays utilizing 3D cell culture systems and their impact on understanding the pathophysiology of BC. Such knowledge could ultimately help to address the most efficient BC treatment.

The role of oncolytic virotherapy and viral oncogenes in the cancer stem cells: a review of virus in cancer stem cells

Cancer Stem Cells (CSCs) are the main "seeds" for the initiation, growth, metastasis, and recurrence of tumors. According to many studies, several viral infections, including the human papillomaviruses, hepatitis B virus, Epstein-Barr virus, and hepatitis C virus, promote the aggressiveness of cancer by encouraging the development of CSC features. Therefore, a better method for the targeted elimination of CSCs and knowledge of their regulatory mechanisms in human carcinogenesis may lead to the development of a future tool for the management and treatment of cancer. Oncolytic viruses (OVs), which include the herpes virus, adenovirus, vaccinia, and reovirus, are also a new class of cancer therapeutics that have favorable properties such as selective replication in tumor cells, delivery of numerous eukaryotic transgene payloads, induction of immunogenic cell death and promotion of antitumor immunity, as well as a tolerable safety profile that essentially differs from that of other cancer therapeutics. The effects of viral infection on the development of CSCs and the suppression of CSCs by OV therapy were examined in this paper. The purpose of this review is to investigate the dual role of viruses in CSCs (oncolytic virotherapy and viral oncogenes).

Exploring the dynamic interplay between cancer stem cells and the tumor microenvironment: implications for novel therapeutic strategies

Cancer stem cells (CSCs) have emerged as key contributors to tumor initiation, growth, and metastasis. In addition, CSCs play a significant role in inducing immune evasion, thereby compromising the effectiveness of cancer treatments. The reciprocal communication between CSCs and the tumor microenvironment (TME) is observed, with the TME providing a supportive niche for CSC survival and self-renewal, while CSCs, in turn, influence the polarization and persistence of the TME, promoting an immunosuppressive state. Consequently, these interactions hinder the efficacy of current cancer therapies, necessitating the exploration of novel therapeutic approaches to modulate the TME and target CSCs. In this review, we highlight the intricate strategies employed by CSCs to evade immune surveillance and develop resistance to therapies. Furthermore, we examine the dynamic interplay between CSCs and the TME, shedding light on how this interaction impacts cancer progression. Moreover, we provide an overview of advanced therapeutic strategies that specifically target CSCs and the TME, which hold promise for future clinical and translational studies in cancer treatment.

Targeted therapy for head and neck squamous cell carcinoma microenvironment

Head and neck squamous cell carcinoma (HNSCC) originates from the squamous epithelium of the oral cavity, oropharynx, larynx, and hypopharynx. HNSCC in the oral cavity and larynx is strongly associated with tobacco smoking and alcohol consumption, while oropharyngeal cancer is increasingly attributed to infection by human papillomavirus (HPV), particularly HPV-16. The tumor microenvironment (TME) is a complex network of cancer cells, immune cells, stromal cells, surrounding blood vessels, and signaling molecules, and plays a critical role in tumor cell survival, invasion, and recurrence. Therefore, it is critical to elucidate the molecular basis of the interaction between tumor cells and the TME in order to develop innovative anti-cancer therapeutic strategies.

Natural killer cell therapy targeting cancer stem cells: Old wine in a new bottle

A small proportion of cancer cells that have stem cell-like properties are known as cancer stem cells (CSCs). They can be used to identify malignant tumor phenotypes and patients with poor prognosis. Targeting these cells has been shown to improve the effectiveness of cancer therapies. Owing to the nature of CSCs, they are resistant to conventional treatment methods such as radio- and chemotherapy. Therefore, more effective anti-CSC therapies are required. Immunotherapy, including natural killer (NK) and T cell therapy, has demonstrated the ability to eliminate CSCs. NK cells have demonstrated superior anti-CSC capabilities compared to T cells in recognizing low levels of major histocompatibility complex (MHC) class I expression. However, CSC escape also occurs during NK cell therapy. It is important to determine CSC-specific immune evasion mechanisms and find out potential solutions to optimize NK cell function. Therefore, this review discusses promising strategies that can improve the efficiency of NK cell therapy in treating CSCs, and aims to provide a reference for future research.

RNA modification: mechanisms and therapeutic targets

RNA modifications are dynamic and reversible chemical modifications on substrate RNA that are regulated by specific modifying enzymes. They play important roles in the regulation of many biological processes in various diseases, such as the development of cancer and other diseases. With the help of advanced sequencing technologies, the role of RNA modifications has caught increasing attention in human diseases in scientific research. In this review, we briefly summarized the basic mechanisms of several common RNA modifications, including m6A, m5C, m1A, m7G, Ψ, A-to-I editing and ac4C. Importantly, we discussed their potential functions in human diseases, including cancer, neurological disorders, cardiovascular diseases, metabolic diseases, genetic and developmental diseases, as well as immune disorders. Through the "writing-erasing-reading" mechanisms, RNA modifications regulate the stability, translation, and localization of pivotal disease-related mRNAs to manipulate disease development. Moreover, we also highlighted in this review all currently available RNA-modifier-targeting small molecular inhibitors or activators, most of which are designed against m6A-related enzymes, such as METTL3, FTO and ALKBH5. This review provides clues for potential clinical therapy as well as future study directions in the RNA modification field. More in-depth studies on RNA modifications, their roles in human diseases and further development of their inhibitors or activators are needed for a thorough understanding of epitranscriptomics as well as diagnosis, treatment, and prognosis of human diseases.

Minimal Residual Disease Detection at RNA and Leukemic Stem Cell (LSC) Levels: Comparison of RT-qPCR, d-PCR and CD26+ Stem Cell Measurements in Chronic Myeloid Leukemia (CML) Patients in Deep Molecular Response (DMR)

A Deep Molecular Response (DMR), defined as a BCR::ABL1 transcript at levels ≤ 0.01% by RT-qPCR, is the prerequisite for the successful interruption of treatment among patients with Chronic Myeloid Leukemia (CML). However, approximately 50% of patients in Treatment-Free Remission (TFR) studies had to resume therapy after their BCR::ABL1 transcript levels rose above the 0.1% threshold. To improve transcript detection sensitivity and accuracy, transcript levels can be analyzed using digital PCR (dPCR). dPCR increases BCR::ABL1 transcript detection sensitivity 10-100 fold; however, its ability to better select successful TFR patients remains unclear. Beyond the role of the immune system, relapses may be due to the presence of residual leukemic stem cells (LSCs) that are transcriptionally silent. Flow cytometry can be used to identify and quantify circulating bone marrow Ph+ LSCs CD34+/CD38- co-expressing CD26 (dipeptidylpeptidase-IV). To date, the significance of circulating Ph+ LSCs in TFR is unclear. The aim of this work is to compare and examine the values obtained using the three different methods of detecting minimal residual disease (MRD) in CML at RNA (RT-qPCR and dPCR) and LSC (flowcytometry) levels among patients in TFR or exhibiting a DMR. The twenty-seven patients enrolled received treatment with either imatinib (12), dasatinib (6), nilotinib (7), bosutinib (1), or interferon (1). Twelve patients were in TFR, while the rest exhibited a DMR. The TFR patients had stopped therapy for less than 1 year (3), <3 years (2), 6 years (6), and 17 years (1). Blood samples were collected and tested using the three methods at the same time. Both d-PCR and LSCs showed higher sensitivity than RT-qPCR, exhibiting positive results in samples that were undetectable using RT-qPCR (17/27). None of the patients tested negative with d-PCR; however, 23/27 were under the threshold of 0.468 copies/μL, corresponding to a stable DMR. The results were divided into quartiles, and the lowest quartiles defined the lowest MRD. These data were strongly correlated in 15/27 patients, corresponding to almost half of the TFR patients. Indeed, the TFR patients, some lasting up to 17 years, corresponded to the lowest detectable DMR categories. To the best of our knowledge, this is the first attempt to analyze and compare DMRs in a CML population using standard (RT-qPCR) and highly sensitive (dPCR and LSCs) methods.

TRIM21 promotes tumor progression and cancer stemness in cervical squamous cell carcinoma

BACKGROUND

The ubiquitin ligase family member triplex motif protein 21 (TRIM21), which is involved in the proliferation, metastasis, and selective death of tumor cells, is crucial in the ubiquitination of a number of tumor marker proteins. As research progresses, more studies demonstrate that TRIM21 expression levels can be used to predict cancer prognosis. However, it is unclear how exactly TRIM21 contributes to cervical squamous carcinoma.

METHODS

Immunohistochemistry, Western Blot, and q-PCR were utilized to determine the expression level of TRIM21 in 113 patients with CESC removed by stage I surgery at Xijing Hospital from 2018 to 2023 using paraffin-embedded tumor tissues and 12 pairs of fresh tumor tissues and their paracancerous tissues. Log-rank analysis using SPSS 23.0 was performed for prognosis and survival analysis using univariate/multifactorial analysis. CCK-8, wound-healing and Scratch assay verified that TRIM21 promoted cell proliferation, migration and invasion. The effect of overexpression and knockdown of TRIM21 on tumor stemness was examined using sphere-forming assay and Western Blot. Finally, we constructed a xenograft model to observe the effect of TRIM21 on tumorigenesis in Si Ha cell lines in vivo.

RESULTS

TRIM21 expression is greater in CESC tissues than in paracancerous tissues, according to immunohistochemical data. Similarly, at the protein and mRNA levels, we verified this conclusion using Western-Blotting and q-PCR. Prognostic and OS analysis showed that TRIM21 expression levels are associated with individual prognostic factors. CCK-8, Wound healing, Transwell, and Sphere-forming tests all demonstrated that TRIM21 overexpression enhances Ca Ski cell proliferation, migration, invasion, and stemness. TRIM21 knockdown in Si Ha inhibited tumor cell proliferation, migration, invasion, and stemness. The experimental results of xenograft models demonstrated that TRIM21 knockdown in Si Ha cells inhibited tumor development.

CONCLUSION

TRIM21 is a poor predictor of prognosis for cervical squamous cell carcinoma and might open up new avenues for investigation into therapeutic targets.

Vienna Cancer Stem Cell Club (VCSCC): 20 year jubilee and future perspectives

INTRODUCTION

The Vienna Cancer Stem Cell Club (VCSCC) was launched by a group of scientists in Vienna in 2002.

AREAS COVERED

Major aims of the VCSCC are to support research on cancer stem cells (CSC) in hematopoietic malignancies and to translate CSC-related markers and targets into clinical application. A primary focus of research in the VCSCC is the leukemic stem cell (LSC). Between 2013 and 2021, members of the VCSCC established a special research program on myeloproliferative neoplasms and since 2008, members of the VCSCC run the Ludwig Boltzmann Institute for Hematology and Oncology. In all these years, the VCSCC provided a robust intellectual platform for translational hematology and LSC research in Vienna. Furthermore, the VCSCC interacts with several national and international study groups and societies in the field. Representatives of the VCSCC also organized a number of international meetings and conferences on neoplastic stem cells, including LSC, in the past 15 years, and contributed to the definition and classification of CSC/LSC and related pre-malignant and malignant conditions.

EXPERT OPINION

The VCSCC will continue to advance the field and to develop LSC-detecting and LSC-eradicating concepts through which diagnosis, prognostication, and therapy of blood cancer patients should improve.

Cellular and Genetic Background of Osteosarcoma

Osteosarcoma describes a tumor of mesenchymal origin with an annual incidence rate of four to five people per million. Even though chemotherapy treatment has shown success in non-metastatic osteosarcoma, metastatic disease still has a low survival rate of 20%. A targeted therapy approach is limited due to high heterogeneity of tumors, and different underlying mutations. In this review, we will summarize new advances obtained by new technologies, such as next generation sequencing and single-cell sequencing. These new techniques have enabled better assessment of cell populations within osteosarcoma, as well as an understanding of the molecular pathogenesis. We also discuss the presence and properties of osteosarcoma stem cells-the cell population within the tumor that is responsible for metastasis, recurrence, and drug resistance.

Phytochemicals and Cancer Treatment: Cell-Derived and Biomimetic Vesicles as Promising Carriers

The majority of anticancer agents currently used derive from natural sources: plants, frequently the ones employed in traditional medicines, are an abundant source of mono- and diterpenes, polyphenols, and alkaloids that exert antitumor activity through diverse mechanisms. Unfortunately, many of these molecules are affected by poor pharmacokinetics and limited specificity, shortcomings that may be overcome by incorporating them into nanovehicles. Cell-derived nanovesicles have recently risen to prominence, due to their biocompatibility, low immunogenicity and, above all, targeting properties. However, due to difficult scalability, the industrial production of biologically-derived vesicles and consequent application in clinics is difficult. As an efficient alternative, bioinspired vesicles deriving from the hybridization of cell-derived and artificial membranes have been conceived, revealing high flexibility and appropriate drug delivery ability. In this review, the most recent advances in the application of these vesicles to the targeted delivery of anticancer actives obtained from plants are presented, with specific focus on vehicle manufacture and characterization, and effectiveness evaluation performed through in vitro and in vivo assays. The emerging overall outlook appears promising in terms of efficient drug loading and selective targeting of tumor cells, suggesting further engrossing developments in the future.