CD44 splice isoform switching determines breast cancer stem cell state.

Although changes in alternative splicing have been observed in cancer, their functional contributions still remain largely unclear. Here we report that splice isoforms of the cancer stem cell (CSC) marker CD44 exhibit strikingly opposite functions in breast cancer. Bioinformatic annotation in patient breast cancer in The Cancer Genome Atlas (TCGA) database reveals that the CD44 standard splice isoform (CD44s) positively associates with the CSC gene signatures, whereas the CD44 variant splice isoforms (CD44v) exhibit an inverse association. We show that CD44s is the predominant isoform expressed in breast CSCs. Elimination of the CD44s isoform impairs CSC traits. Conversely, manipulating the splicing regulator ESRP1 to shift alternative splicing from CD44v to CD44s leads to an induction of CSC properties. We further demonstrate that CD44s activates the PDGFRß/Stat3 cascade to promote CSC traits. These results reveal CD44 isoform specificity in CSC and non-CSC states and suggest that alternative splicing provides functional gene versatility that is essential for distinct cancer cell states and thus cancer phenotypes.

Single-cell transcriptomics reveals the intra-tumoral heterogeneity and SQSTM1/P62 and Wnt/ß-catenin mediated epithelial to mesenchymal transition and stemness of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is characterized by the complex tumor microenvironment (TME) consisting of an abundance of mesenchymal stem cells (MSCs), which is known to facilitate epithelial-to-mesenchymal transition (EMT). The development of single-cell genomics is a powerful method for defining the intricate genetic landscapes of malignancies. In this study, we have employed single-cell RNA sequencing (scRNA-seq) to dissect the intra-tumoral heterogeneity and analyze the single-cell transcriptomic landscape to detect rare consequential cell subpopulations of significance. The scRNA-seq analysis of TNBC and Normal patient derived samples revealed that EMT markers and transcription factors were most upregulated in MSC population. Further, exploration of gene expression analysis among TNBC and Normal patient-derived MSCs ascertained the role of SQSTM1/P62 and Wnt/ß-catenin in TNBC progression. Wnt/ß-catenin and Wnt/PCP signaling pathways are prominent contributors of EMT, stemness, and cancer stem cell (CSC) properties of TNBC. SQSTM1/P62 cooperates with the components of the Wnt/PCP signaling pathway and is critically involved at the interface of autophagy and EMT. Moreover, siRNA targeting SQSTM1/P62 and inhibitor of Wnt/ß-catenin (FH535) in conjunction was used to explore molecular modification of EMT and stemness markers. Although SQSTM1/P62 is not crucial for cell survival, cytotoxicity assay revealed synergistic interaction between the siRNA/inhibitor. Modulation of these important pathways helped in reduction of expression of genes and proteins contributing to CSC properties. Gene and protein expression analysis revealed the induction of EMT to MET. Moreover, co-treatment resulted in inactivation of non-canonical Wnt VANGL2-JNK signaling axis. The synergistic impact of inhibition of SQSTM1/P62 and Wnt/ß-catenin signaling facilitates the development of a potential therapeutic regimen for TNBC.

Transcriptional factors targeting in cancer stem cells for tumor modulation.

Cancer Stem Cells (CSCs) are now considered the primary "seeds" for the onset, development, metastasis, and recurrence of tumors. Despite therapeutic breakthroughs, cancer remains the leading cause of death worldwide. This is because the tumor microenvironment contains a key population of cells known as CSCs, which promote tumor aggression. CSCs are self-renewing cells that aid tumor recurrence by promoting tumor growth and persisting in patients after many traditional cancer treatments. According to reports, numerous transcription factors (TF) play a key role in maintaining CSC pluripotency and its self-renewal property. The understanding of the functions, structures, and interactional dynamics of these transcription factors with DNA has modified the hypothesis, paving the way for novel transcription factor-targeted therapies. These TFs, which are crucial and are required by cancer cells, play a vital function in the etiology of human cancer. Such CSC TFs will help with gene expression profiling, which provides crucial data for predicting the prognosis of patients. To overcome anti-cancer medication resistance and completely eradicate cancer, a potent therapy combining TFs-based CSC targets with traditional chemotherapy may be developed. In order to develop therapies that could eliminate CSCs, we here concentrated on the effect of TFs and other components of signalling pathways on cancer stemness.

Five amino acid mismatches in the zinc-finger domains of Cellulose Synthase 5 and Cellulose Synthase 6 cooperatively modulate their functional properties by controlling homodimerization in Arabidopsis.

Cellulose synthase 5 (CESA5) and CESA6 are known to share substantial functional overlap. In the zinc-finger domain (ZN) of CESA5, there are five amino acid (AA) mismatches when compared to CESA6. These mismatches in CESA5 were replaced with their CESA6 counterparts one by one until all were replaced, generating nine engineered CESA5s. Each N-terminal enhanced yellow fluorescent protein-tagged engineered CESA5 was introduced to prc1-1, a cesa6 null mutant, and resulting mutants were subjected to phenotypic analyses. We found that five single AA-replaced CESA5 proteins partially rescue the prc1-1 mutant phenotypes to different extents. Multi-AA replaced CESA5s further rescued the mutant phenotypes in an additive manner, culminating in full recovery by CESA5G43R + S49T+S54P+S80A+Y88F. Investigations in cellulose content, cellulose synthase complex (CSC) motility, and cellulose microfibril organization in the same mutants support the results of the phenotypic analyses. Bimolecular fluorescence complementation assays demonstrated that the level of homodimerization in every engineered CESA5 is substantially higher than CESA5. The mean fluorescence intensity of CSCs carrying each engineered CESA5 fluctuates with the degree to which the prc1-1 mutant phenotypes are rescued by introducing a corresponding engineered CESA5. Taken together, these five AA mismatches in the ZNs of CESA5 and CESA6 cooperatively modulate the functional properties of these CESAs by controlling their homodimerization capacity, which in turn imposes proportional changes on the incorporation of these CESAs into CSCs.

Mechanism of DAPK1 for Regulating Cancer Stem Cells in Thyroid Cancer.

Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin (Ca2+/CaM)-dependent serine/threonine (Ser/Thr) protein kinase and is characteristically downregulated in metastatic cancer. Several studies showed that DAPK1 is involved in both the early and late stages of cancer. DAPK1 downregulation is elaborately controlled by epigenetic, transcriptional, posttranscriptional, and posttranslational processes. DAPK1 is known to regulate not only cancer cells but also stromal cells. Recent studies showed that DAPK1 was involved not only in tumor suppression but also in epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) formation in colon and thyroid cancers. CSCs are major factors in determining cancer aggressiveness in cancer metastasis and treatment prognosis by influencing EMT. However, the molecular mechanism involved in the regulation of cancer cells by DAPK1 remains unclear. In particular, little is known about the existence of CSCs and how they are regulated in papillary thyroid carcinoma (PTC) among thyroid cancers. In this review, we describe the molecular mechanism of CSC regulation by DAPK1 in PTC progression.

CFAP61 is required for sperm flagellum formation and male fertility in human and mouse.

Defects in the structure or motility of cilia and flagella may lead to severe diseases such as primary ciliary dyskinesia (PCD), a multisystemic disorder with heterogeneous manifestations affecting primarily respiratory and reproductive functions. We report that CFAP61 is a conserved component of the calmodulin- and radial spoke-associated complex (CSC) of cilia. We find that a CFAP61 splice variant, c.143+5G>A, causes exon skipping/intron retention in human, inducing a multiple morphological abnormalities of the flagella (MMAF) phenotype. We generated Cfap61 knockout mice that recapitulate the infertility phenotype of the human CFAP61 mutation, but without other symptoms usually observed in PCD. We find that CFAP61 interacts with the CSC, radial spoke stalk and head. During early stages of Cfap61-/- spermatid development, the assembly of radial spoke components is impaired. As spermiogenesis progresses, the axoneme in Cfap61-/- cells becomes unstable and scatters, and the distribution of intraflagellar transport proteins is disrupted. This study reveals an organ-specific mechanism of axoneme stabilization that is related to male infertility.

Efficacy of Whole Cancer Stem Cell-Based Vaccines: A Systematic Review of Preclinical and Clinical Studies.

BACKGROUND: Despite the conventional cancer therapeutic, cancer treatment remains a medical challenge due to neoplasm metastasis and cancer recurrence; therefore, new approaches promoting therapeutic strategies are highly desirable. As a new therapy, the use of whole neoplastic stem cells or cancer stem cell (CSC)-based vaccines is one strategy to overcome these obstacles. We investigated the effects of whole CSC-based vaccines on the solid tumor development, metastasis, and survival rate. METHODS: Primary electronic databases (PubMed/MEDLINE, Scopus, Embase, and Web of Science) and a major clinical registry were searched. Interventional studies of whole CSC-based vaccines in rodent cancer models (38 studies) and human cancer patients (11 studies) were included; the vaccine preparation methodologies, effects, and overall outcomes were evaluated. RESULTS: Preclinical studies were divided into 4 groups: CSC-lysates/ inactivated-CSC-based vaccines, CSC-lysate-loaded dendritic cell (CSC-DC) vaccines, cytotoxic T-cell (CTL) vaccines generated with CSC-DC (CSC-DC-CTL), and combinatorial treatments carried out in the prophylactic and therapeutic experimental models. The majority of preclinical studies reported a promising effect on tumor growth, survival rate, and metastasis. Moreover, whole CSC-based vaccines induced several antitumor immune responses. A small number of clinical investigations suggested that the whole CSC-based vaccine treatment is beneficial; however, further research is required. CONCLUSIONS: This comprehensive review provides an overview of the available methods for assessing the efficacy of whole CSC-based vaccines on tumor development, metastasis, and survival rate. In addition, it presents a set of recommendations for designing high-quality clinical studies that may allow to determine the efficacy of whole CSC-based-vaccines in cancer therapy.

An Investigation into the In Vitro Targeted Killing of CD44-Expressing Triple-Negative Breast Cancer Cells Using Recombinant Photoimmunotherapeutics Compared to Auristatin-F-Based Antibody-Drug Conjugates.

Triple-negative breast cancer (TNBC) is the deadliest form of breast cancer with limited treatment options. The persistence of highly tumorigenic CD44-expressing subpopulation referred to as cancer stem cells (CSCs), endowed with the self-renewal capacity, has been associated with therapeutic resistance, hence clinical relapses. To mitigate these undesired events, targeted immunotherapies using antibody-photoconjugate (APC) or antibody-drug conjugate (ADC), were developed to specifically release cytotoxic payloads within targeted cells overexpressing cognate antigen receptors. Therefore, an αCD44(scFv)-SNAP-tag antibody fusion protein was engineered through genetic fusion of a single-chain antibody fragment (scFv) to a SNAPf-tag fusion protein, capable of self-conjugating with benzylguanine-modified light-sensitive near-infrared (NIR) phthalocyanine dye IRDye700DX (BG-IR700) or the small molecule toxin auristatin-F (BG-AURIF). Binding of the αCD44(scFv)-SNAPf-IR700 photoimmunoconjugate to antigen-positive cells was demonstrated by confocal microscopy and flow cytometry. By switching to NIR irradiation, CD44-expressing TNBC was selectively killed through induced phototoxic activities. Likewise, the αCD44(scFv)-SNAPf-AURIF immunoconjugate was able to selectively accumulate within targeted cells and significantly reduced cell viability through antimitotic activities at nano- to micromolar drug concentrations. This study provides an in vitro proof-of-concept for a future strategy to selectively destroy light-accessible superficial CD44-expressing TNBC tumors and their metastatic lesions which are inaccessible to therapeutic light.

Morphological and Functional Correlations in Acute Central Serous Chorioretinopathy.

PURPOSE: We evaluate morphological and functional correlations in patients with acute central serous chorioretinopathy (CSC). METHODS: A prospective study was conducted on 50 patients with an acute CSC episode lasting less than 3 months. At baseline, assessments included optical coherence tomography (OCT), best-corrected visual acuity (BCVA), contrast sensitivity (CS), microperimetry (MP), and multifocal electroretinography (mfERG). A correlation analysis between OCT morphological parameters (maximal subretinal fluid height (SRF), central retinal thickness (CRT), and macular volume (MV)) and functional parameters was conducted on the affected eye for each patient. RESULTS: Among the morphological parameters, SRF showed the strongest correlations with functional parameters (r absolute value range = 0.10-0.70). Weak correlations were observed between BCVA and morphological parameters (r absolute value range = 0.14-0.26). Average retinal sensitivity (MP-A) was the functional parameter displaying the most robust negative correlation with morphological parameters (r absolute value range = 0.61-0.70). In contrast, average contrast sensitivity (CS-A) and mfERG average amplitude density in the first (mfERG-A1) and second (mfERG-A2) ring showed weak to moderate (r absolute value range = 0.35-0.56) yet statistically significantly nonzero correlations. CONCLUSIONS: SRF and CRT could serve as the most representative morphological proxies for visual function deficit in acute CSC patients. Retinal sensitivity, as measured by MP, may be superior to BCVA in clinical research studies or when an in-depth visual function evaluation is needed.

Quantitative assessment of choroidal parameters and retinal thickness in central serous chorioretinopathy using ultra-widefield swept-source optical coherence tomography: a cross-sectional study.

OBJECTIVE: In this study, we used ultra-wide field swept-source optical coherence tomography angiography (UWF SS-OCTA) to assess changes in retinal thickness (RT) and choroidal parameters in individuals who had received a diagnosis of central serous chorioretinopathy (CSC). METHODS: The study encompassed the evaluation of 59 eyes from 47 patients with a diagnosis of CSC, alongside 33 fellow eyes and 31 eyes from healthy individuals (controls). The parameters assessed included RT, choroidal thickness (CT), choriocapillaris density, vascular density of the large choroidal vessel layer, three-dimensional choroidal vascularity index (3D-CVI), choroidal vessel volume per unit area (mCVV/a), and choroidal stroma volume per unit area (mCSV/a). RESULTS: Metrics including mCVV/a, mCSV/a, 3D-CVI, CT, and RT exhibited significantly elevated values in the eyes affected by CSC compared to those of the control group across nine subfields. Moreover, a substantial number of the subfields in both CSC-affected and fellow eyes exhibited increased values for mCVV/a, mCSV/a, 3D-CVI, CT, and RT when compared with the control group. Additionally, acute and chronic CSC subfields demonstrated significantly elevated values for mCVV/a, mCSV/a, 3D-CVI, CT, and RT in comparison to healthy control eyes. Notably, specific subfields associated with complex and atypical forms of CSC revealed higher metrics compared to those of the control group. CONCLUSION: In conclusion, the UWF SS-OCTA proved to be a valuable tool for exploring the anatomical etiology and clinical classification and diagnosis of CSC.

Quantitative optical coherence tomography angiography assessments in the fellow eyes of those with central serous chorioretinopathy.

BACKGROUND: To analyze the vessel density (VD) of the retina and choriocapillaris (CC) layer and the structure of the foveal avascular zone (FAZ) in the fellow eyes of central serous chorioretinopathy (CSC) patients by using optical coherence tomography angiography (OCTA). METHODS: This was a case-control study. Unilateral CSC patients and age-matched healthy subjects were recruited from the Affiliated Eye Hospital of Wenzhou Medical University between July 2016 and July 2021. All eyes were divided into three groups: acute CSC (aCSC), chronic CSC (cCSC), and healthy controls. Both aCSC and cCSC were again divided into two subgroups: the affected eyes and the fellow eyes. In this study, all parameters of VD and FAZ were measured by self-software of OCTA. RESULTS: A total of 231 eyes of 137 subjects were included, with 47 aCSC patients, 47 cCSC patients, and 43 healthy controls. In the fellow eyes of CSC, the retinal VD was significantly lower (all P < 0.05), and the FAZ was significantly larger (all P < 0.05) in the cCSC group than in healthy controls, while no difference was detected in the CC layer. There was no significant difference between the aCSC group and healthy controls in all OCTA parameters. In the affected eyes of CSC, the superficial retinal vessel density (SRVD) was significantly higher (all P < 0.05) in healthy controls than in the aCSC and cCSC groups, while the deep retinal vessel density (DRVD) was significantly lower (all P < 0.05) and the FAZ was larger (all P < 0.05) in the cCSC group than in the aCSC group and healthy controls. A liner regression equation was established: Y (BCVA, best corrected visual acuity) = 3.692-0.036✱X1 (DRVD-Fovea)-0.031✱X2 (FD-300, vessel density around the 300 µm width of the FAZ), R2 = 0.427. CONCLUSION: Based on OCTA measurements, this study revealed that the retinal microvascular network was impaired even in the fellow eyes of those with cCSC, which should arouse attention to the observation of unilateral CSC.

Preclinical Repurposing of Sitagliptin as a Drug Candidate for Colorectal Cancer by Targeting CD24/CTNNB1/SOX4-Centered Signaling Hub.

Despite significant advances in treatment modalities, colorectal cancer (CRC) remains a poorly understood and highly lethal malignancy worldwide. Cancer stem cells (CSCs) and the tumor microenvironment (TME) have been shown to play critical roles in initiating and promoting CRC progression, metastasis, and treatment resistance. Therefore, a better understanding of the underlying mechanisms contributing to the generation and maintenance of CSCs is crucial to developing CSC-specific therapeutics and improving the current standard of care for CRC patients. To this end, we used a bioinformatics approach to identify increased CD24/SOX4 expression in CRC samples associated with poor prognosis. We also discovered a novel population of tumor-infiltrating CD24+ cancer-associated fibroblasts (CAFs), suggesting that the CD24/SOX4-centered signaling hub could be a potential therapeutic target. Pathway networking analysis revealed a connection between the CD24/SOX4-centered signaling, ß-catenin, and DPP4. Emerging evidence indicates that DPP4 plays a role in CRC initiation and progression, implicating its involvement in generating CSCs. Based on these bioinformatics data, we investigated whether sitagliptin, a DPP4 inhibitor and diabetic drug, could be repurposed to inhibit colon CSCs. Using a molecular docking approach, we demonstrated that sitagliptin targeted CD24/SOX4-centered signaling molecules with high affinity. In vitro experimental data showed that sitagliptin treatment suppressed CRC tumorigenic properties and worked in synergy with 5FU and this study thus provided preclinical evidence to support the alternative use of sitagliptin for treating CRC.

Tobacco Smoke Condensate Induces Morphologic Changes in Human Papillomavirus-Positive Cervical Epithelial Cells Consistent with Epithelial to Mesenchymal Transition (EMT) with Activation of Receptor Tyrosine Kinases and Regulation of TGFB.

High-risk human papillomavirus (HR-HPV; HPV-16) and cigarette smoking are associated with cervical cancer (CC); however, the underlying mechanism(s) remain unclear. Additionally, the carcinogenic components of tobacco have been found in the cervical mucus of women smokers. Here, we determined the effects of cigarette smoke condensate (CSC; 3R4F) on human ectocervical cells (HPV-16 Ect/E6E7) exposed to CSC at various concentrations (10-6-100 µg/mL). We found CSC (10-3 or 10 µg/mL)-induced proliferation, enhanced migration, and histologic and electron microscopic changes consistent with EMT in ectocervical cells with a significant reduction in E-cadherin and an increase in the vimentin expression compared to controls at 72 h. There was increased phosphorylation of receptor tyrosine kinases (RTKs), including Eph receptors, FGFR, PDGFRA/B, and DDR2, with downstream Ras/MAPK/ERK1/2 activation and upregulation of common EMT-related genes, TGFB SNAI2, PDGFRB, and SMAD2. Our study demonstrated that CSC induces EMT in ectocervical cells with the upregulation of EMT-related genes, expression of protein biomarkers, and activation of RTKs that regulate TGFB expression, and other EMT-related genes. Understanding the molecular pathways and environmental factors that initiate EMT in ectocervical cells will help delineate molecular targets for intervention and define the role of EMT in the initiation and progression of cervical intraepithelial neoplasia and CC.

Targeting CSC-related transcription factors by E3 ubiquitin ligases for cancer therapy.

Evidence has revealed that transcription factors play essential roles in regulation of multiple cellular processes, including cell proliferation, metastasis, EMT, cancer stem cells and chemoresistance. Dysregulated expression levels of transcription factors contribute to tumorigenesis and malignant progression. The expression of transcription factors is tightly governed by several signaling pathways, noncoding RNAs and E3 ubiquitin ligases. Cancer stem cells (CSCs) have been validated in regulation of tumor metastasis, reoccurrence and chemoresistance in human cancer. Transcription factors have been verified to participate in regulation of CSC formation, including Oct4, SOX2, KLF4, c-Myc, Nanog, GATA, SALL4, Bmi-1, OLIG2, POU3F2 and FOX proteins. In this review article, we will describe the critical role of CSC-related transcription factors. We will further discuss which E3 ligases regulate the degradation of these CSC-related transcription factors and their underlying mechanisms. We also mentioned the functions and mechanisms of EMT-associated transcription factors such as ZEB1, ZEB2, Snail, Slug, Twist1 and Twist2. Furthermore, we highlight the therapeutic potential via targeting E3 ubiquitin ligases for modulation of these transcription factors.

Programmed death ligand 1 regulates epithelial-mesenchymal transition and cancer stem cell phenotypes in hepatocellular carcinoma through the serum and glucocorticoid kinase 2/ß-catenin signaling pathway.

Programmed death ligand 1 (PD-L1) plays an important role in the occurrence of hepatocellular carcinoma (HCC). The present study indicated that epithelial-mesenchymal transition (EMT) and induction of cancer stem cell (CSC)-like properties contribute to metastasis of cancers. However, the molecular mechanisms underlying PD-L1 and EMT and CSC phenotypes in HCC remain to be elucidated. Here, we report that PD-L1 regulates not only EMT but also the stem-like transition in liver cancer cells. We observed high PD-L1 expression in CD133+ liver CSCs and CSC-enriched tumor spheres. Altering PD-L1 expression promoted liver CSC phenotypes by increasing the expression of stemness genes, the CD133+ cell population sizes, and the ability to form tumor spheres. Programmed death ligand 1 enhanced HCC cell tumorigenicity and invasion in nude mice. Additionally, PD-L1 overexpression in cells significantly increased cell motility and invasion, as well as the EMT process. Conversely, suppression of PD-L1 in cells had an opposite effect. Prolonged treatment of HCC cells with Akt inhibitor prefosine leads to activation of serum and glucocorticoid kinase 2 (SGK2) and rescued downregulation of PD-L1. Mechanistically, PD-L1 directly interacted with SGK2. Programmed death ligand 1 upregulated SGK2 and activated the SGK2/ß-catenin signaling pathway, and promoted EMT and CSC expansion in liver cancer cells, highlighting the role of SGK2 in PD-L1-mediated EMT and CSC phenotypes in liver cancer cells. In conclusion, our findings suggest that PD-L1 activated the SGK2/ß-catenin signaling pathway, to induce EMT and acquisition of a stem cell phenotype.

High expression of PKCλ and ALDH1A3 indicates a poor prognosis, and PKCλ is required for the asymmetric cell division of ALDH1A3-positive cancer stem cells in PDAC.

Pancreatic ductal adenocarcinoma (PDAC) is the cancer with the poorest prognosis. One of the major properties reflecting its poor prognosis is high-grade heterogeneity, which leads to insensitivity to anticancer treatments. Cancer stem cells (CSCs) acquire phenotypic heterogeneity, generating abnormally differentiated cells by asymmetric cell division. However, the detailed mechanism leading to phenotypic heterogeneity is largely unknown. Here, we showed that PDAC patients with co-upregulation of PKCλ and ALDH1A3 had the poorest clinical outcome. PKCλ knockdown by DsiRNA in the ALDH1high population of PDAC MIA-PaCa-2 cells attenuated the asymmetric distribution of the ALDH1A3 protein. To monitor asymmetric cell division of ALDH1A3-positive PDAC CSCs, we established stable Panc-1 PDAC clones expressing ALDH1A3-turboGFP (Panc-1-ALDH1A3-turboGFP cells). In addition to MIA-PaCa-2-ALDH1high cells, turboGFPhigh cells sorted from Panc-1-ALDH1A3-turboGFP cells showed asymmetric cell propagation of ALDH1A3 protein. PKCλ DsiRNA in Panc-1-ALDH1A3-turboGFP cells also attenuated the asymmetric distribution of ALDH1A3 protein. These results suggest that PKCλ regulates the asymmetric cell division of ALDH1A3-positive PDAC CSCs. Furthermore, Panc-1-ALDH1A3-turboGFP cells can be useful for the visualization and monitoring of CSC properties such as asymmetric cell division of ALDH1A3-positive PDAC CSCs in time-lapse imaging.

Effective inhibition of breast cancer stem cell properties by quercetin-loaded solid lipid nanoparticles via reduction of Smad2/Smad3 phosphorylation and ß-catenin signaling pathway in triple-negative breast cancer.

BACKGROUND: The presence of cancer stem cells (CSCs) is a major cause of resistance to cancer therapy and recurrence. Triple-negative breast cancer (TNBC) is a subtype that responds poorly to therapy, making it a significant global health issue. Quercetin (QC) has been shown to affect CSC viability, but its low bioavailability limits its clinical use. This study aims to increase the effectiveness of QC in inhibiting CSC generation by using solid lipid nanoparticles (SLNs) in MDA-MB231 cells. MATERIALS AND METHODS: After treating MCF-7 and MDA-MB231 cells with 18.9 µM and 13.4 µM of QC and QC-SLN for 48 h, respectively, cell viability, migration, sphere formation, protein expression of ß-catenin, p-Smad 2 and 3, and gene expression of EMT and CSC markers were evaluated. RESULTS: The QC-SLN with particle size of 154 nm, zeta potential of -27.7 mV, and encapsulation efficacy of 99.6% was found to be the most effective. Compared to QC, QC-SLN significantly reduced cell viability, migration, sphere formation, protein expression of ß-catenin and p-Smad 2 and 3, and gene expression of CD44, zinc finger E-box binding homeobox 1 (ZEB1), vimentin, while increasing the gene expression of E-cadherin. CONCLUSIONS: Our findings demonstrate that SLNs improve the cytotoxic effect of QC in MDA-MB231 cells by increasing its bioavailability and inhibiting epithelial-mesenchymal transition (EMT), thereby effectively inhibiting CSC generation. Therefore, SLNs could be a promising new treatment for TNBC, but more in vivo studies are needed to confirm their efficacy.

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.

Tumor matrix stiffness provides fertile soil for cancer stem cells.

Matrix stiffness is a mechanical characteristic of the extracellular matrix (ECM) that increases from the tumor core to the tumor periphery in a gradient pattern in a variety of solid tumors and can promote proliferation, invasion, metastasis, drug resistance, and recurrence. Cancer stem cells (CSCs) are a rare subpopulation of tumor cells with self-renewal, asymmetric cell division, and differentiation capabilities. CSCs are thought to be responsible for metastasis, tumor recurrence, chemotherapy resistance, and consequently poor clinical outcomes. Evidence suggests that matrix stiffness can activate receptors and mechanosensor/mechanoregulator proteins such as integrin, FAK, and YAP, modulating the characteristics of tumor cells as well as CSCs through different molecular signaling pathways. A deeper understanding of the effect of matrix stiffness on CSCs characteristics could lead to development of innovative cancer therapies. In this review, we discuss how the stiffness of the ECM is sensed by the cells and how the cells respond to this environmental change as well as the effect of matrix stiffness on CSCs characteristics and also the key malignant processes such as proliferation and EMT. Then, we specifically focus on how increased matrix stiffness affects CSCs in breast, lung, liver, pancreatic, and colorectal cancers. We also discuss how the molecules responsible for increased matrix stiffness and the signaling pathways activated by the enhanced stiffness can be manipulated as a therapeutic strategy for cancer.

Cancer stem cells and their niche in cancer progression and therapy.

High recurrence and metastasis rates and poor prognoses are the major challenges of current cancer therapy. Mounting evidence suggests that cancer stem cells (CSCs) play an important role in cancer development, chemoradiotherapy resistance, recurrence, and metastasis. Therefore, targeted CSC therapy has become a new strategy for solving the problems of cancer metastasis and recurrence. Since the properties of CSCs are regulated by the specific tumour microenvironment, the so-called CSC niche, which targets crosstalk between CSCs and their niches, is vital in our pursuit of new therapeutic opportunities to prevent cancer from recurring. In this review, we aim to highlight the factors within the CSC niche that have important roles in regulating CSC properties, including the extracellular matrix (ECM), stromal cells (e.g., associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), and mesenchymal stem cells (MSCs)), and physiological changes (e.g., inflammation, hypoxia, and angiogenesis). We also discuss recent progress regarding therapies targeting CSCs and their niche to elucidate developments of more effective therapeutic strategies to eliminate cancer.