Regulation Of Cancer Stem Cells Research Articles

P52-ZER6/IGF1R axis maintains cancer stem cell population to promote cancer progression by enhancing pro-survival mitophagy.

Cancer stem cells (CSCs), which are distinct subpopulations of tumor cells, have a substantially higher tumor-initiating capacity and are closely related to poor clinical outcomes. Damage to organelles can trigger CSC pool exhaustion; however, the underlying mechanisms are poorly understood. ZER6 is a zinc-finger protein with two isoforms possessing different amino termini: p52-ZER6 and p71-ZER6. Since their discovery, almost no study reported on their biological and pathological functions. Herein, we found that p52-ZER6 was crucial for CSC population maintenance; p52-ZER6-knocking down almost abolished the tumor initiation capability. Through transcriptomic analyses together with in vitro and in vivo studies, we identified insulin like growth factor 1 receptor (IGF1R) as the transcriptional target of p52-ZER6 that mediated p52-ZER6 regulation of CSC by promoting pro-survival mitophagy. Moreover, this regulation of mitophagy-mediated CSC population maintenance is specific to p52-ZER6, as p71-ZER6 failed to exert the same effect, most possibly due to the presence of the HUB1 domain at its N-terminus. These results provide a new perspective on the regulatory pathway of pro-survival mitophagy in tumor cells and the molecular mechanism underlying p52-ZER6 oncogenic activity, suggesting that targeting p52-ZER6/IGF1R axis to induce CSC pool exhaustion may be a promising anti-tumor therapeutic strategy.

Deciphering the dual roles of PHD finger proteins from oncogenic drivers to tumor suppressors

PHD (plant homeodomain) finger proteins emerge as central epigenetic readers and modulators in cancer biology, orchestrating a broad spectrum of cellular processes pivotal to oncogenesis and tumor suppression. This review delineates the dualistic roles of PHD fingers in cancer, highlighting their involvement in chromatin remodeling, gene expression regulation, and interactions with cellular signaling networks. PHD fingers’ ability to interpret specific histone modifications underscores their influence on gene expression patterns, impacting crucial cancer-related processes such as cell proliferation, DNA repair, and apoptosis. The review delves into the oncogenic potential of certain PHD finger proteins, exemplified by PHF1 and PHF8, which promote tumor progression through epigenetic dysregulation and modulation of signaling pathways like Wnt and TGFβ. Conversely, it discusses the tumor-suppressive functions of PHD finger proteins, such as PHF2 and members of the ING family, which uphold genomic stability and inhibit tumor growth through their interactions with chromatin and transcriptional regulators. Additionally, the review explores the therapeutic potential of targeting PHD finger proteins in cancer treatment, considering their pivotal roles in regulating cancer stem cells and influencing the immune response to cancer therapy. Through a comprehensive synthesis of current insights, this review underscores the complex but promising landscape of PHD finger proteins in cancer biology, advocating for further research to unlock novel therapeutic avenues that leverage their unique cellular roles.

Deciphering the role of transcription factors in glioblastoma cancer stem cells.

Glioblastoma (GBM), the most aggressive and fatal brain malignancy, is largely driven by a subset of tumor cells known as cancer stem cells (CSCs). CSCs possess stem cell-like properties, including self-renewal, proliferation, and differentiation, making them pivotal for tumor initiation, invasion, metastasis, and overall tumor progression. The regulation of CSCs is primarily controlled by transcription factors (TFs) which regulate the expressions of genes involved in maintaining stemness and directing differentiation. This review aims to provide a comprehensive overview of the role of TFs in regulating CSCs in GBM. The discussion encompasses the definitions of CSCs and TFs, the significance of glioma stem cells (GSCs) in GBM, and how TFs regulate GSC self-renewal, proliferation, differentiation, and transformation. The potential for developing TF-targeted GSC therapies is also explored, along with future research directions. By understanding the regulation of GSCs by TFs, we may uncover novel diagnostic and therapeutic strategies against this devastating disease of GBM.

Seedless black Vitis vinifera polyphenols suppress hepatocellular carcinoma in vitro and in vivo by targeting apoptosis, cancer stem cells, and proliferation

Hepatocellular carcinoma (HCC) is an aggressive tumor and one of the most challenging cancers to treat. Here, we evaluated the in vitro and in vivo ameliorating impacts of seedless black Vitis vinifera (VV) polyphenols on HCC. Following the preparation of the VV crude extract (VVCE) from seedless VV (pulp and skin), three fractions (VVF1, VVF2, and VVF3) were prepared. The anticancer potencies of the prepared fractions, compared to 5-FU, were assessed against HepG2 and Huh7 cells. In addition, the effects of these fractions on p-dimethylaminoazobenzene-induced HCC in mice were evaluated. The predicted impacts of selected phenolic constituents of VV fractions on the activity of essential HCC-associated enzymes (NADPH oxidase “NADPH-NOX2”, histone deacetylase 1 “HDAC1”, and sepiapterin reductase “SepR”) were analyzed using molecular docking. The results showed that VVCE and its fractions induced apoptosis and collapsed CD133+ stem cells in the studied cancer cell lines with an efficiency greater than 5-FU. VVF1 and VVF2 exhibited the most effective anticancer fractions in vitro; therefore, we evaluated their influences in mice. VVF1 and VVF2 improved liver morphology and function, induced apoptosis, and lowered the fold expression of various crucial genes that regulate cancer stem cells and other vital pathways for HCC progression. For most of the examined parameters, VVF1 and VVF2 had higher potency than 5-FU, and VVF1 showed more efficiency than VVF2. The selected phenolic compounds displayed competitive inhibitory action on NADPH-NOX2, HDAC1, and SepR. In conclusion, these findings declare that VV polyphenolic fractions, particularly VVF1, could be promising safe anti-HCC agents.

The pRb/RBL2-E2F1/4-GCN5 axis regulates cancer stem cell formation and G0 phase entry/exit by paracrine mechanisms

The lethality, chemoresistance and metastatic characteristics of cancers are associated with phenotypically plastic cancer stem cells (CSCs). How the non-cell autonomous signalling pathways and cell-autonomous transcriptional machinery orchestrate the stem cell-like characteristics of CSCs is still poorly understood. Here we use a quantitative proteomic approach for identifying secreted proteins of CSCs in pancreatic cancer. We uncover that the cell-autonomous E2F1/4-pRb/RBL2 axis balances non-cell-autonomous signalling in healthy ductal cells but becomes deregulated upon KRAS mutation. E2F1 and E2F4 induce whereas pRb/RBL2 reduce WNT ligand expression (e.g. WNT7A, WNT7B, WNT10A, WNT4) thereby regulating self-renewal, chemoresistance and invasiveness of CSCs in both PDAC and breast cancer, and fibroblast proliferation. Screening for epigenetic enzymes identifies GCN5 as a regulator of CSCs that deposits H3K9ac onto WNT promoters and enhancers. Collectively, paracrine signalling pathways are controlled by the E2F-GCN5-RB axis in diverse cancers and this could be a therapeutic target for eliminating CSCs.

Circadian regulation of cancer stem cells and the tumor microenvironment during metastasis.

The circadian clock regulates daily rhythms of numerous physiological activities through tightly coordinated modulation of gene expression and biochemical functions. Circadian disruption is associated with enhanced tumor formation and metastasis via dysregulation of key biological processes and modulation of cancer stem cells (CSCs) and their specialized microenvironment. Here, we review how the circadian clock influences CSCs and their local tumor niches in the context of different stages of tumor metastasis. Identifying circadian therapeutic targets could facilitate the development of new treatments that leverage circadian modulation to ablate tumor-resident CSCs, inhibit tumor metastasis and enhance response to current therapies.

Neil 1 deficiency facilitates chemoresistance through upregulation of RAD18 expression in ovarian cancer stem cells

Over the past decades, cancer stem cells (CSCs) have emerged as a critical subset of tumor cells associated with tumor recurrence and resistance to chemotherapy. Understanding the mechanisms underlying CSC-mediated chemoresistance is imperative for improving cancer therapy outcomes. This study delves into the regulatory role of NEIL1, a DNA glycosylase, in chemoresistance in ovarian CSCs.We first observed a decreased expression of NEIL1 in ovarian CSCs, suggesting its potential involvement in CSC regulation. Using pan-cancer analysis, we confirmed the diminished NEIL1 expression in ovarian tumors compared to normal tissues. Furthermore, NEIL1 downregulation correlated with an increase in stemness markers and enrichment of CSCs, highlighting its role in modulating CSC phenotype.Further mechanistic investigation revealed an inverse correlation between NEIL1 and RAD18 expression in ovarian CSCs. NEIL1 depletion led to heightened RAD18 expression, promoting chemoresistance possibly via enhancing Translesion DNA Synthesis (TLS)-mediated DNA lesion bypass. Moreover, dowregulation of NEIL1 results in reduced DNA damage accumulation and suppressed apoptosis in ovarian cancer.Overall, our findings unveil a novel mechanism involving NEIL1 and RAD18 in regulating chemoresistance in ovarian CSCs. Targeting this NEIL1-RAD18 axis may offer promising therapeutic strategies for combating chemoresistance and improving ovarian cancer treatment outcomes.

Abstract LB047: Pdcd10 is a promising therapeutic target for head and neck squamous cell carcinoma

Abstract Oral cavity squamous cell carcinoma (OCSCC), the most common subtype of head and neck cancer, is a devastating disease, causing substantial morbidity and mortality. Only a handful of targeted therapies are available for OCSCC, and the 5-year overall survival remains ~50%. While strategies are being designed to improve risk assessment, detection, and therapeutic intervention, these approaches are limited by our incomplete understanding of OCSCC biology, particularly in its early development. Thus, it is crucial to identify novel targets of therapeutic interest. Programmed cell death 10 (PDCD10) is a multifaceted protein shown to be overexpressed in several solid malignancies. It was reported that PDCD10 may contribute to tumorigenesis and chemoresistance by promoting cell proliferation, anti-apoptosis, epithelial-mesenchymal transition (EMT), and inhibiting anti-tumor immune responses. Recently it was suggested that PDCD10 is involved in regulating cancer stem cells (CSCs) maintenance in breast and lung cancers. While targeting PDCD10 activity may provide novel strategies for treating HPV- HNSCC, the direct relevance of PDCD10 in regulating head and neck tumorigenesis has not yet been studied. The goal of this study was to evaluate the role of PDCD10 in driving oral malignant transformation and investigate whether PDCD10 inhibition can induce anti-cancer effect. We first generated stable PDCD10 knockdown clones using two human OCSCC cell lines and showed that PDCD10 depletion effects oral cancer cell physiology (such as proliferation, DNA replication, migration, and invasion). We next used organoid models established from normal oral epidermis of tamoxifen inducible Pdcd10F/F and control Pdcd10+/+ mice to investigate the role of PDCD10 in driving oral tumorigenesis and regulating stem cell maintenance following malignant transformation induced by 4NQO treatment. Finally, we used mice with inducible Pdcd10 knockout in tongue epithelia to evaluate the ability of PDCD10 depletion to inhibit the 4NQO induced oral carcinogenesis in vivo. Taken together, our data provide strong evidence that PDCD10 is an oncogene that may promote oral neoplastic progression, posing PDCD10 as a potential therapeutic target for patients with OCSCC. Given the devastating nature of oral cancer and dearth of effective treatment, providing new insights into the cancer driving molecular mechanisms regulated by PDCD10 and using this knowledge for developing therapeutic approaches targeting its activity may ultimately improve patients' prognosis. Citation Format: Manu Sundaresan, Xiangying Cheng, Claudia WIng, Alexander von Kumberg, Elena Jochum, Alka Singh, Joseph Kainov, Piao Zhao, Mohammed Sidahmed, Alexander T. Pearson, Ari J. Rosenberg, Nishant Agrawal, Le Shen, Evgeny Izumchenko. Pdcd10 is a promising therapeutic target for head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB047.

Abstract 1668: Association of stem cell-like phenotype with isoform specific functions of AKTs in hepatocytes

Abstract Introduction: Liver cancer is the sixth most common cancer and the third leading cause of cancer-related deaths worldwide. It is associated with abnormal activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, which is implicated in regulation of cancer stem cells (CSCs). The present study investigated the effects of AKT loss on stem cell-like phenotype in immortalized mouse hepatocytes. Methods: Immortalized hepatocytes were established from mice with Akt1 (Akt1−/−; Akt1-null) or Akt2 (Akt2−/−; Akt2-null) whole-body deletion. Cell morphology was assessed via microscopy. Cell proliferation was evaluated with hemacytometer count and MTT assay. Cell migration towards a chemoattractant was assessed via transwell assay. Cell viability was evaluated in response to chemotherapy treatment. The ability of cells to Results: When compared to WT cells, which exhibited cuboidal epithelial-like features, Akt1-null and Akt2-null cells demonstrated elongated mesenchymal-like morphology. Loss of either isoform was associated with a significantly decreased cell growth (p<0.05). Akt1-null cells migrated faster towards a chemoattractant in the transwell assay, were significantly more resistant to sorafenib, and formed a significantly higher number of spheres in the sphere formation assay (p<0.01). Proteomic analysis revealed that both Akt1-null and Akt2-null cells exhibited increased expression of CSC marker CD44, along with other proteins associated with liver cancer, including PDGFRA, CDH2, MMP14, and COX2 (p<0.05). Additionally, Akt1-null cells exhibited elevated levels of ANXA1 and ANXA3 (p<0.01). Conclusions: Loss of both AKT isoforms resulted in decreased cell proliferation and elevated expression of proteins with a previously reported role in liver cancer invasion, migration, and epithelial-mesenchymal transition. AKT1 loss correlated with an enhanced stem cell-like phenotype, including increased migration towards a chemoattractant, higher resistance to chemotherapy, and enhanced ability to form spheres. These results contribute to the understanding of the role of AKT isoforms in regulating stemness in liver cancer and may serve as a basis for investigation into isoform specific inhibitors. Further investigation into cellular mechanisms governing these phenotypes is required. Citation Format: Ielyzaveta Slarve, Yushan Wang, Mario Alba, Lina He, Bangyan Stiles. Association of stem cell-like phenotype with isoform specific functions of AKTs in hepatocytes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1668.

Abstract 1794: PAF1 reprograms metabolism in pancreatic cancer by interacting with HIF1α

Abstract Background: Reprogrammed cellular metabolism has been refocused on in the past decade, as many cancer cells rewire various metabolic pathways to facilitate their survival, unlimited cell growth, and division. RNA Polymerase II-Associated Factor 1 (PAF1)/Pancreatic Differentiation 2 (PD2) is a core subunit of the human PAF1 Complex (PAF1C) that regulates the RNA polymerase II function during transcriptional elongation in normal cells; however, its overexpression has been implicated in promoting pancreatic tumorigenesis and metastasis through epigenetic regulation, chemoresistance, radioresistance and maintenance of cancer stem cells. While most of these studies have provided evidence of the multifunctional nature of PAF1/PD2 in PDAC progression, no study has investigated the role of PAF1/PD2 during the metabolic rewiring of cancer. Methods: In this study, we sought to examine the role of PAF1/PD2 in the metabolic rewiring of cancer cells in pancreatic ductal adenocarcinoma (PDAC) and decipher how PAF1/PD2 mediates this metabolic reprogramming in PDAC. Pancreatic cancer cell lines were transfected with shRNAs to knock down PAF1/PD2. Metabolic genes regulated by PAF1/PD2 were identified by qPCR and western blot upon PAF1/PD2 depletion. Metabolic assays were performed to investigate the role of PAF1/PD2. Immunoprecipitations identified proteins that interact with PAF1/PD2. Confocal microscopy confirmed the co-localization of PAF1/PD2 with its protein partners. We performed chromatin immunoprecipitation (ChIP) - Polymerase chain reaction to confirm the binding of the PAF1 sub-complex to its target gene. Results: Our results showed that pancreatic cancer cells depleted PAF1/PD2 downregulate genes involved in aerobic glycolysis compared to control cells. Also, the lactate release assay indicated that more lactate was produced in control cells than in cells with PAF1/PD2 knockdown. Interestingly, we identified that HIF1α interacts with PAF1, specifically in pancreatic cancer cells. PAF1 and HIF1α co-localization was observed in pancreatic cancer cell lines. We also observed that the PAF1/PD2- HIF1α complex bound to the promoter region of LDHA to regulate the expression of LDHA in pancreatic cancer cells, reprogramming the metabolism to utilize the aerobic glycolysis pathway preferentially. Conclusions: In conclusion, our study shows that PAF1/PD2 rewires the metabolism of PDAC by interacting with HIF1 α to regulate the expression of LDHA, which is the rate-limiting step of aerobic glycolysis. Citation Format: Ayoola O. Ogunleye, Neelanjana Gayen, Saravanakumar Marimuthu, Rama Krishna Nimmakayala, Sanchita Rauth, Zahraa Alsafwani, Jesse L. Cox, Surinder K. Batra, Moorthy P. Ponnusamy. PAF1 reprograms metabolism in pancreatic cancer by interacting with HIF1α [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1794.

Abstract 5443: Identifying key regulators of glioblastoma cancer stem cells

Abstract Glioblastoma multiforme (GBM) has a dire prognosis that has had little progress over the past three decades. The existence of a unique population of stem-like gene signature baring quiescent cells (GSCs) within GBM are important for GBM tumorigenesis, therapy-resistance and recurrence. Our lab has developed one of the most faithful genetically engineered mouse models, encompassing a Nestin promoter-enhancer driven CreERT2-H2BeGFP-hDTR cassette (hereafter as CGD), that allows us to accurately capture and isolate GSCs in mouse GBM. The next logical step is to leverage these tools to uncover therapeutic vulnerabilities of GSCs and make a meaningful impact on GBM patient outcomes. To our knowledge, very few studies have explored the functional regulators of GSCs using a CRISPR/Cas9 screening approach. Our GSC signature provides a strong foundation for performing targeted in vitro or in vivo screens. In this study, to identify functionally important genes that may regulate GSC self-renewal and tumorigenic properties, an in vitro CRISPR knockout screens using a gene library derived from the GSC signature. The viral library was applied to low passage primary cultures of FACS sorted CGD_GFP+ and CGD_GFP- GBM cells developed from CGD; Nf1f/+;Trp53f/f;Ptenf/+ mice, respectively. The result of our in vitro CRISPR knock-out screen demonstrated guide depletion of Atp1b2-sgRNA in CGD_GFP+ but not in CGD_GFP- cells. The main objective of this study is to utilize in vitro and in vivo functional assays to test the difference between Atp1b2 WT and Atp1b2 KO GSCs and Atp1b2 WT vs KO GSC-derived tumors. Having a targeted candidate gene list is also particularly helpful for designing an in vivo CRISPR knockout screen, which is more physiological relevant. Therefore, I propose to use the candidate gene list derived from the in vitro screen as a starting point. The in vivo screen can provide valuable insights for the selection of the most optimal candidates for anti-GSC therapies. Citation Format: Tao Wang, Xuanhua Xie, Luis F. Parada. Identifying key regulators of glioblastoma cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5443.

Regulation of cancer stem cells by CXCL1, a chemokine whose secretion is controlled by MCM2

BackgroundA high expression pattern of minichromosome maintenance 2 (MCM2) has been observed in various cancers. MCM2 is a protein involved in the cell cycle and plays a role in cancer growth and differentiation by binding to six members of the MCM subfamily. The MCM protein family includes MCM2 through MCM7.MethodsMCM2 has shown high expression in both lung cancer stem cells (LCSCs) and glioma stem cells (GSCs). We investigated the characteristics of CSCs and the regulation of the epithelial-to-mesenchymal transition (EMT) phenomenon in LCSCs and GSCs by MCM2. Additionally, we explored secreted factors regulated by MCM2.ResultsThere was a significant difference in survival rates between lung cancer patients and brain cancer patients based on MCM2 expression. MCM2 was found to regulate both markers and regulatory proteins in LCSCs. Moreover, MCM2 is thought to be involved in cancer metastasis by regulating cell migration and invasion, not limited to lung cancer but also identified in glioma. Among chemokines, chemokine (C-X-C motif) ligand 1 (CXCL1) was found to be regulated by MCM2.ConclusionsMCM2 not only participates in the cell cycle but also affects cancer cell growth by regulating the external microenvironment to create a favorable environment for cells. MCM2 is highly expressed in malignant carcinomas, including CSCs, and contributes to the malignancy of various cancers. Therefore, MCM2 may represent a crucial target for cancer therapeutics.

MiR-29a-KLF4 signaling inhibits breast tumor initiation by regulating cancer stem cells

Cancer stem cells (CSCs) are known for their potent ability to drive tumor initiation and recurrence, yet the molecular mechanisms regulating CSCs are still unclear. Our study found a positive correlation between increased levels of miR-29a and better survival rates in early-stage breast cancer patients, but a negative correlation in late-stage patients, suggesting a dual function of miR-29a in regulating breast cancer. Furthermore, miR-29a showed significant downregulation in the ALDH+ breast cancer stem cell population compared to non-stem cancer cells. Overexpression of miR-29a in human breast cancer cells reduced the proportion of CSCs, suppressed their ability to form mammospheres, and inhibited the expression of stemness genes SOX2, KLF4, and hTERT in vitro. Conversely, knockdown of miR-29a in breast cancer cells showed opposite effects. Tumor xenograft experiments revealed that miR-29a overexpression significantly inhibited tumorigenesis initiated by MDA-MB-231 cell transplantation in nude mice. We further demonstrated that Krüppel-like factor 4 (KLF4), a key gene that regulates cell stemness, was a direct target of miR-29a in breast cancer cells. miR-29a suppressed the expression of KLF4 at both mRNA and protein levels. Reintroduction of KLF4 into breast cancer cells rescued the miR-29a-induced CSC suppression phenotype. In summary, our study is the first to demonstrate that miR-29a-KLF4 signaling inhibits breast tumor initiation by regulating CSCs, which provides novel therapeutic targets for preventing breast tumor initiation.

Concentric Hybrid Nanoelectrospray Ionization-Atmospheric Pressure Chemical Ionization Source for High-Coverage Mass Spectrometry Analysis of Single-Cell Metabolomics.

High-coverage mass spectrometry analysis of single-cell metabolomics remains challenging due to the extremely low abundance and wide polarity of metabolites and ultra-small volume in single cells. Herein, a novel concentric hybrid ionization source, nanoelectrospray ionization-atmospheric pressure chemical ionization (nanoESI-APCI), is ingeniously designed to detect polar and nonpolar metabolites simultaneously in single cells. The source is constructed by inserting a pulled glass capillary coaxially into a glass tube that acts as a dielectric barrier layer. Benefitting from the integrated advantages of nanoESI and APCI, its limit of detection is improved by one order of magnitude to 10 pgmL-1. After the operational parameter optimization, 254 metabolites detected in nanoESI-APCI are tentatively identified from a single cell, and 82 more than those in nanoESI. The developed nanoESI-APCI is successively applied to study the metabolic heterogeneity of human hepatocellular carcinoma tissue microenvironment united with laser capture microdissection (LCM), the discrimination of cancer cell types and subtypes, the metabolic perturbations to glucose starvation in MCF7 cells and the metabolic regulation of cancer stem cells. These results demonstrated that the nanoESI-APCI not only opens a new avenue for high-coverage and high-sensitivity metabolomics analysis of single cell, but also facilitates spatially resolved metabolomics study coupled with LCM.

Multifaceted role of microRNAs in gastric cancer stem cells: Mechanisms and potential biomarkers.

MicroRNAs (miRNAs) have received much attention in the past decade as potential key epigenomic regulators of tumors and cancer stem cells (CSCs). The abnormal expression of miRNAs is responsible for different phenotypes of gastric cancer stem cells (GCSCs). Some specific miRNAs could be used as promising biomarkers and therapeutic targets for the identification of GCSCs. This review summarizes the coding process and biological functions of miRNAs and demonstrates their role and efficacy in gastric cancer (GC) metastasis, drug resistance, and apoptosis, especially in the regulatory mechanism of GCSCs. It shows that the overexpression of onco-miRNAs and silencing of tumor-suppressor miRNAs can play a role in promoting or inhibiting tumor metastasis, apart from the initial formation of GC. It also discusses the epigenetic regulation and potential clinical applications of miRNAs as well as the role of CSCs in the pathogenesis of GC. We believe that this review may help in designing novel therapeutic approaches for GC.

Revealing role of epigenetic modifiers and DNA oxidation in cell-autonomous regulation of Cancer stem cells

BackgroundBreast cancer cells (BCCs) can remain undetected for decades in dormancy. These quiescent cells are similar to cancer stem cells (CSCs); hence their ability to initiate tertiary metastasis. Dormancy can be regulated by components of the tissue microenvironment such as bone marrow mesenchymal stem cells (MSCs) that release exosomes to dedifferentiate BCCs into CSCs. The exosomes cargo includes histone 3, lysine 4 (H3K4) methyltransferases - KMT2B and KMT2D. A less studied mechanism of CSC maintenance is the process of cell-autonomous regulation, leading us to examine the roles for KMT2B and KMT2D in sustaining CSCs, and their potential as drug targets.MethodsUse of pharmacological inhibitor of H3K4 (WDR5–0103), knockdown (KD) of KMT2B or KMT2D in BCCs, real time PCR, western blot, response to chemotherapy, RNA-seq, and flow cytometry for circulating markers of CSCs and DNA hydroxylases in BC patients. In vivo studies using a dormancy model studied the effects of KMT2B/D to chemotherapy.ResultsH3K4 methyltransferases sustain cell autonomous regulation of CSCs, impart chemoresistance, maintain cycling quiescence, and reduce migration and proliferation of BCCs. In vivo studies validated KMT2’s role in dormancy and identified these genes as potential drug targets. DNA methylase (DNMT), predicted within a network with KMT2 to regulate CSCs, was determined to sustain circulating CSC-like in the blood of patients.ConclusionH3K4 methyltransferases and DNA methylation mediate cell autonomous regulation to sustain CSC. The findings provide crucial insights into epigenetic regulatory mechanisms underlying BC dormancy with KMT2B and KMT2D as potential therapeutic targets, along with standard care. Stem cell and epigenetic markers in circulating BCCs could monitor treatment response and this could be significant for long BC remission to partly address health disparity.

Interventing mitochondrial PD-L1 suppressed IFN-γ-induced cancer stemness in hepatocellular carcinoma by sensitizing sorafenib-induced ferroptosis

Evidence recently showed that pleiotropic cytokine interferon-gamma (IFN-γ) in the tumor microenvironment (TME) plays a positive role in hepatocellular carcinoma (HCC) progression through the regulation of liver cancer stem cells (LCSCs) in HCC. The present study explored the role and potential mechanism of mitochondrial programmed cell death-ligand 1 (PD-L1) and its regulation of ferroptosis in modulating the cancer stemness of LCSCs. It was shown that mimicking TME IFN-γ exposure increased the LCSCs ratio and cancer stemness phenotypes in HCC cells. IFN-γ exposure inhibited sorafenib (Sora)-induced ferroptosis by enhancing glutathione peroxidase 4 (GPX4) expression as well reactive oxygen species (ROS) and lipid peroxidation (LPO) generation in LCSCs. Furthermore, IFN-γ exposure upregulated PD-L1 expression and its mitochondrial translocation, inducing dynamin-related protein 1 (Drp1)-dependent mitochondrial fission and correlating with glycolytic metabolism reprogramming in LCSCs. The genetic intervention of PD-L1 promoted ferroptosis-dependent anti-tumor effects of Sora, reduced glycolytic metabolism reprogramming, and inhibited cancer stemness of HCC in vitro and in vivo. Our results revealed a novel mechanism that IFN-γ exposure-induced mitochondrial translocation of PD-L1 enhanced glycolytic reprogramming to mediate the GPX4-dependent ferroptosis resistance and cancer stemness in LCSCs. This study provided new insights into the role of mitochondrial PD-L1-Drp1-GPX4 signal axis in regulating IFN-γ exposure-associated cancer stemness in LCSCs and verified that PD-L1-targeted intervention in combination with Sora might achieve promising synergistic anti-HCC effects.

Hyperbaric Oxygen Boosts Antitumor Efficacy of Copper-Diethyldithiocarbamate Nanoparticles against Pancreatic Ductal Adenocarcinoma by Regulating Cancer Stem Cell Metabolism.

Cuproptosis-based cancer nanomedicine has received widespread attention recently. However, cuproptosis nanomedicine against pancreatic ductal adenocarcinoma (PDAC) is severely limited by cancer stem cells (CSCs), which reside in the hypoxic stroma and adopt glycolysis metabolism accordingly to resist cuproptosis-induced mitochondria damage. Here, we leverage hyperbaric oxygen (HBO) to regulate CSC metabolism by overcoming tumor hypoxia and to augment CSC elimination efficacy of polydopamine and hydroxyethyl starch stabilized copper-diethyldithiocarbamate nanoparticles (CuET@PH NPs). Mechanistically, while HBO and CuET@PH NPs inhibit glycolysis and oxidative phosphorylation, respectively, the combination of HBO and CuET@PH NPs potently suppresses energy metabolism of CSCs, thereby achieving robust tumor inhibition of PDAC and elongating mice survival importantly. This study reveals novel insights into the effects of cuproptosis nanomedicine on PDAC CSC metabolism and suggests that the combination of HBO with cuproptosis nanomedicine holds significant clinical translation potential for PDAC patients.

DOT1L promotes expression of CD44 through the Wnt/β-catenin signaling pathway in early gastric carcinoma.

To assess telomere silencing 1-like (DOTIL) gene expression within gastric cancer (GC) tissues as well as its function of promoting cancer stem cell (CSC)-mediated epithelial-mesenchymal switching, tissue samples from 8 patients each in 3 stages (normal, low-grade intraepithelial neoplasia (LGIN), as well as early gastric carcinoma (EGC)) were collected for whole-exome sequencing, which revealed differentially expressed genes (DEGs). The DEGs and their prognostic value were verified through TCGA and GTEx analyses. We also verified the role of DOT1L in EGC development. We collected samples from three patients each with LGIN and EGC for single-cell sequencing. We conducted single-cell transcriptomic analysis, DEG analysis, cell‒cell interaction analysis, and pseudotime analysis using R language. Sites and levels of DOT1L, CD44 and DOT1L expression were verified by IF. We found 703 deleterious mutation sites in the LGIN group and 389 deleterious mutation sites in the EGC group. The LGIN as well as EGC categories exhibited increased levels of DOT1L expression compared to the standard category (P<0.05) in TCGA and GTEx. DOT1L also correlated significantly with TMB (P=8.45E-06), MSI (P=0.001), and tumor proliferation index (P=7.17E-09) in the TCGA and GTEx datasets. In single cells, we found that DOT1L promotes CD44 expression via the Wnt/β-catenin signaling pathway and the development for stemness properties within GC. In addition, we found that DOT1L, CD44 and CTNNB1 colocalize and correlate positively. In conclusion, one important CSC regulator in GC, DOT1L may be crucial in coordinating the expression of genes specific to a certain lineage during MSC development.

Transcriptomics analysis reveals distinct mechanism of breast cancer stem cells regulation in mammospheres from MCF-7 and T47D cells

Luminal A breast cancer, constituting 70 % of breast cancer cases, presents a challenge due to the development of resistance and recurrence caused by breast cancer stem cells (BCSC). Luminal breast tumors are characterized by TP53 expression, a tumor suppressor gene involved in maintaining stem cell attributes in cancer. Although a previous study successfully developed mammospheres (MS) from MCF-7 (with wild-type TP53) and T47D (with mutant TP53) luminal breast cancer cells for BCSC enrichment, their transcriptomic profiles remain unclear. We aimed to elucidate the transcriptomic disparities between MS of MCF-7 and T47D cells using bioinformatics analyses of differentially expressed genes (DEGs), including the KEGG pathway, Gene Ontology (GO), drug-gene association, disease-gene association, Gene Set Enrichment Analysis (GSEA), DNA methylation analysis, correlation analysis of DEGs with immune cell infiltration, and association analysis of genes and small-molecule compounds via the Connectivity Map (CMap). Upregulated DEGs were enriched in metabolism-related KEGG pathways, whereas downregulated DEGs were enriched in the MAPK signaling pathway. Drug-gene association analysis revealed that both upregulated and downregulated DEGs were associated with fostamatinib. The KEGG pathway GSEA results indicated that the DEGs were enriched for oxidative phosphorylation, whereas the downregulated DEGs were negatively enriched for the p53 signaling pathway. Examination of DNA methylation revealed a noticeable disparity in the expression patterns of the PKM2, ERO1L, SLC6A6, EPAS1, APLP2, RPL10L, and NEDD4 genes when comparing cohorts with low- and high-risk breast cancer. Furthermore, a significant positive correlation was identified between SLC6A6 expression and macrophage presence, as well as MSN, and AKR1B1 expression and neutrophil and dentritic cell infiltration. CMap analysis unveiled SA-83851 as a potential candidate to counteract the effects of DEGs, specifically in cells harbouring mutant TP53. Further research, including in vitro and in vivo validations, is warranted to develop drugs targeting BCSCs.