Cancer stem cells: the challenges ahead

Circulating tumor cells in solid malignancies: From advanced isolation technologies to biological understanding and clinical relevance in early diagnosis and prognosis

Circulating tumor cells (CTCs) are shed from primary tumors and travel through the body via circulation, eventually settling to form micrometastases under favorable conditions. Numerous studies have identified CTCs as a negative prognostic indicator for survival across various cancer types. CTCs mirror the current heterogeneity and genetic and biological state of tumors, making their study invaluable for understanding tumor progression, cell senescence, and cancer dormancy. However, their isolation and characterization still poses a major challenge that limits their clinical translation. A wide array of methods, each with different levels of specificity, utility, cost, and sensitivity, have been developed to isolate and characterize CTCs. Moreover, innovative techniques are emerging to address the limitations of existing methods. In this review, we provide insights into CTC biology addressing spectra of markers employed for molecular analysis and functional characterization. It also emphasizes current label-dependent and label-independent isolation procedures, addressing their strengths and limitations. SIGNIFICANCE: A comprehensive overview of CTC biology, their molecular and functional characterization, along with their current clinical utility will help in understanding the present-day extent to which the clinical potential of CTCs is getting tapped in personalized medicine.

Hedgehog Pathway Is a Regulator of Stemness in HER2-Positive Trastuzumab-Resistant Breast Cancer

HER2 overexpression occurs in 20-30% of breast cancers and is associated with poor prognosis. Trastuzumab is a standard treatment for HER2-positive breast cancer; however, resistance develops in approximately 50% of patients within a year. The Hedgehog (Hh) signalling pathway, known for its role in maintaining stemness in various cancers, may contribute to trastuzumab resistance in HER2-positive breast cancer. This study aimed to investigate the role of Hedgehog signalling in maintaining stemness and contributing to trastuzumab resistance in HER2-positive breast cancer cell lines. Trastuzumab-resistant HER2-positive breast cancer cell lines, SKBR3 and HCC1954, were developed through continuous trastuzumab exposure. Cells were treated with GANT61 (Hh inhibitor, IC50:10 µM) or SAG21K (Hh activator, IC50:100 nM) for 24 h to evaluate the Hedgehog signalling response. Stemness marker expression (Nanog, Sox2, Bmi1, Oct4) was measured using qRT-PCR. The combination index (CI) of GANT61 with trastuzumab was calculated using CompuSyn software (version 1.0) to identify synergistic doses (CI < 1). The synergistic concentrations' impact on stemness markers was assessed. Data were analysed using two-way ANOVA and Tukey's post hoc test (p < 0.05). Trastuzumab-resistant cells exhibited increased Hedgehog signalling activity. Treatment with GANT61 significantly downregulated stemness marker expression, while SAG21K treatment led to their upregulation in both SKBR3-R and HCC1954-R cells. The combination of GANT61 and trastuzumab demonstrated a synergistic effect, markedly reducing the expression of stemness markers. These findings indicate that Hedgehog signalling plays a pivotal role in maintaining stemness in trastuzumab-resistant cells, and that the inhibition of this pathway may prevent tumour progression. Hedgehog signalling is crucial in regulating stemness in trastuzumab-resistant HER2-positive breast cancer. Targeting this pathway could overcome resistance and enhance trastuzumab efficacy. Further studies should explore the clinical potential of Hedgehog inhibitors in combination therapies.

FOXP4 Is a Direct YAP1 Target That Promotes Gastric Cancer Stemness and Drives Metastasis

The Hippo-YAP1 pathway is an evolutionally conserved signaling cascade that controls organ size and tissue regeneration. Dysregulation of Hippo-YAP1 signaling promotes initiation and progression of several types of cancer, including gastric cancer. As the Hippo-YAP1 pathway regulates expression of thousands of genes, it is important to establish which target genes contribute to the oncogenic program driven by YAP1 to identify strategies to circumvent it. In this study, we identified a vital role of forkhead box protein 4 (FOXP4) in YAP1-driven gastric carcinogenesis by maintaining stemness and promoting peritoneal metastasis. Loss of FOXP4 impaired gastric cancer spheroid formation and reduced stemness marker expression, whereas FOXP4 upregulation potentiated cancer cell stemness. RNA sequencing analysis revealed SOX12 as a downstream target of FOXP4, and functional studies established that SOX12 supports stemness in YAP1-induced carcinogenesis. A small-molecule screen identified 42-(2-tetrazolyl) rapamycin as a FOXP4 inhibitor, and targeting FOXP4 suppressed gastric cancer tumor growth and enhanced the efficacy of 5-fluorouracil chemotherapy in vivo. Collectively, these findings revealed that FOXP4 upregulation by YAP1 in gastric cancer regulates stemness and tumorigenesis by upregulating SOX12. Targeting the YAP1-FOXP4-SOX12 axis represents a potential therapeutic strategy for gastric cancer. Significance: Hippo-YAP1 signaling maintains stemness in gastric cancer by upregulating FOXP4, identifying FOXP4 as a stemness biomarker and therapeutic target that could help improve patient outcomes.

ONC212, alone or in synergistic conjunction with Navitoclax (ABT-263), promotes cancer cell apoptosis via unconventional mitochondrial-independent caspase-3 activation

Mitochondria-targeting agents, known as mitocans, are emerging as potent cancer therapeutics due to pronounced metabolic and apoptotic adaptations in the mitochondria of cancer cells. ONC212, an imipridone-family compound initially identified as a ClpP agonist, is currently under investigation as a potential mitocan with demonstrated preclinical efficacy against multiple malignancies. Despite this efficacy, the molecular mechanism underlying the cell death induced by ONC212 remains unclear. This study systematically investigates the mitochondrial involvement and signaling cascades associated with ONC212-induced cell death, utilizing HeLa and A549 cancer cells. Treated cancer cells exhibited characteristic apoptotic features, such as annexin-V positivity and caspase-3 activation; however, these occurred independently of typical mitochondrial events like membrane potential loss (ΔΨm) and cytochrome c release, as well as caspase-8 activation associated with the extrinsic pathway. Additionally, ONC212 treatment increased the expression of anti-apoptotic proteins Bcl-2 and Bcl-xL, which impeded apoptosis, as the overexpression of Bcl-2-GFP and Bcl-xL-GFP significantly reduced ONC212-mediated cell death. Furthermore, combining a sub-lethal dose of the Bcl-2/Bcl-xL inhibitor Navitoclax with ONC212 markedly augmented caspase-3 activation and cell death, still without any notable ΔΨm loss or cytochrome c release. Moreover, inhibition of caspase-9 activity unexpectedly augmented, rather than attenuated, caspase-3 activation and the subsequent cell death. Collectively, our research identifies ONC212 as an atypical mitochondrial-independent, yet Bcl-2/Bcl-xL-inhibitable, caspase-3-mediated apoptotic cell death inducer, highlighting its potential for combination therapies in tumors with defective mitochondrial apoptotic signaling.

Cancer-associated fibroblasts-secreted exosomal miR-92a-3p promotes tumor growth and stemness in hepatocellular carcinoma through activation of Wnt/β-catenin signaling pathway by suppressing AXIN1

Cancer-associated fibroblasts (CAFs) are a major cellular component in the tumor microenvironment and have been shown to exhibit protumorigenic effects in hepatocellular carcinoma (HCC). This study aimed to delve into the mechanisms underlying the tumor-promoting effects of CAFs in HCC. Small RNA sequencing was conducted to screen differential expressed microRNAs in exosomes derived from CAFs and normal fibroblasts (NFs). The miR-92a-3p expression was then measured using reverse transcriptase quantitative real-time PCR in CAFs, NFs, CAFs-derived exosomes (CAFs-Exo), and NF-derived exosomes (NFs-Exo). Compared to NFs or NF-Exo, CAFs and CAFs-Exo significantly promoted HCC cell proliferation, migration, and stemness. Additionally, compared to NFs or NF-Exo, miR-92a-3p level was notably higher in CAFs and CAFs-Exo, respectively. Exosomal miR-92a-3p was found to enhance HCC cell proliferation, migration, and stemness. Meanwhile, AXIN1 was targeted by miR-92a-3p. Exosomal miR-92a-3p could activate β-catenin/CD44 signaling in HCC cells by inhibiting AXIN1 messenger RNA. Furthermore, in vivo studies verified that exosomal miR-92a-3p notably promoted tumor growth and stemness through targeting AXIN1/β-catenin axis. Collectively, CAFs secreted exosomal miR-92a-3p was capable of promoting growth and stemness in HCC through activation of Wnt/β-catenin signaling pathway by suppressing AXIN1. Therefore, targeting CAFs-derived miR-92a-3p may be a potential strategy for treating HCC.

Targeting of human cancer stem cells predicts efficacy and toxicity of FDA-approved oncology drugs

Cancer remains the leading cause of death worldwide with approved oncology drugs continuing to have heterogenous patient responses and accompanied adverse effects (AEs) that limits effectiveness. Here, we examined >100 FDA-approved oncology drugs in the context of stemness using a surrogate model of transformed human pluripotent cancer stem cells (CSCs) vs. healthy stem cells (hSCs) capable of distinguishing abnormal self-renewal and differentiation. Although a proportion of these drugs had no effects (inactive), a larger portion affected CSCs (active), and a unique subset preferentially affected CSCs over hSCs (selective). Single cell gene expression and protein profiling of each drug's FDA recognized target provided a molecular correlation of responses in CSCs vs. hSCs. Uniquely, drugs selective for CSCs demonstrated clinical efficacy, measured by overall survival, and reduced AEs. Our findings reveal that while unintentional, half of anticancer drugs are active against CSCs and associated with improved clinical outcomes. Based on these findings, we suggest ability to target CSC targeting should be included as a property of early onco-therapeutic development.

Drug tolerant persister cell plasticity in cancer: A revolutionary strategy for more effective anticancer therapies

Non-genetic mechanisms have recently emerged as important drivers of anticancer drug resistance. Among these, the drug tolerant persister (DTP) cell phenotype is attracting more and more attention and giving a predominant non-genetic role in cancer therapy resistance. The DTP phenotype is characterized by a quiescent or slow-cell-cycle reversible state of the cancer cell subpopulation and inert specialization to stimuli, which tolerates anticancer drug exposure to some extent through the interaction of multiple underlying mechanisms and recovering growth and proliferation after drug withdrawal, ultimately leading to treatment resistance and cancer recurrence. Therefore, targeting DTP cells is anticipated to provide new treatment opportunities for cancer patients, although our current knowledge of these DTP cells in treatment resistance remains limited. In this review, we provide a comprehensive overview of the formation characteristics and underlying drug tolerant mechanisms of DTP cells, investigate the potential drugs for DTP (including preclinical drugs, novel use for old drugs, and natural products) based on different medicine models, and discuss the necessity and feasibility of anti-DTP therapy, related application forms, and future issues that will need to be addressed to advance this emerging field towards clinical applications. Nonetheless, understanding the novel functions of DTP cells may enable us to develop new more effective anticancer therapy and improve clinical outcomes for cancer patients.

Graphene Quantum Dots Eradicate Resistant and Metastatic Cancer Cells by Enhanced Interfacial Inhibition

Drug-resistant and metastatic cancer cells such as a small population of cancer stem cells (CSCs) play a crucial role in metastasis and relapse. Conventional small-molecule chemotherapeutics, however, are unable to eradicate drug-resistant CSCs owing to limited interface inhibitory effects. Herein, it is reported that enhanced interfacial inhibition leading to eradication of drug-resistant CSCs can be dramatically induced by self-insertion of bioactive graphene quantum dots (GQDs) into DNA major groove (MAG) sites in cancer cells. Since transcription factors regulate gene expression at the MAG site, MAG-targeted GQDs exert greatly enhanced interfacial inhibition, downregulating the expression of a collection of cancer stem genes such as ALDH1, Notch1, and Bmi1. Moreover, the nanoscale interface inhibition mechanism reverses cancer multidrug resistance (MDR) by inhibiting MDR1 gene expression when GQDs are used at a nontoxic concentration (1/4 × half-maximal inhibitory concentration (IC50)) as the MDR reverser. Given their high efficacy in interfacial inhibition, CSC-mediated migration, invasion, and metastasis of cancer cells can be substantially blocked by MAG-targeted GQDs, which can also be harnessed to sensitize clinical cytotoxic agents for improved efficacy in combination chemotherapy. These findings elucidate the inhibitory effects of the enhanced nano-bio interface at the MAG site on eradicating CSCs, thus preventing cancer metastasis and recurrence.

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

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

Identification of placenta-specific protein 1 (PLAC-1) expression on human PC-3 cell line-derived prostate cancer stem cells compared to the tumor parental cells

Placenta-specific protein 1 (PLAC-1) is a gene primarily expressed in the placenta and the testis. Interestingly, it is also found to be expressed in many solid tumors, and it is involved in malignant cell features. However, no evidence has been reported regarding the relationship between PLAC-1 and cancer stem cells (CSCs). In the current research, we explored the expression of the PLAC-1 molecule in prostate cancer stem cells (PCSCs) derived from the human PC-3 cell line. The enrichment of PCSCs was achieved using a three-dimensional cell culture technique known as the sphere-formation assay. To confirm the identity of PCSCs, we examined the expression of genes associated with stemness and pluripotency, such as SOX2, OCT4, Nanog, C-Myc, and KLF-4, as well as stem cell differentiation molecules like CD44 and CD133. These evaluations were conducted in both the PCSCs and the original tumor cells (parental cells) using real-time PCR and flow cytometry. Subsequently, we assessed the expression of the PLAC-1 molecule in both enriched cells and parental tumor cells at the gene and protein levels using the same techniques. The tumor cells from the PC-3 cell line formed spheroids with CSC characteristics in a non-adherent medium. The expression of SOX2, OCT4, Nanog, and C-Myc genes (p < 0.01), and the molecules CD44 and CD133 (p < 0.05) were significantly elevated in PCSCs compared to the parental cells. The expression of the PLAC-1 molecule in PCSCs showed a significant increase compared to the parental cells at both gene (p < 0.01) and protein (p < 0.001) levels. In conclusion, it was indicated for the first time that PLAC-1 is up-regulated in PCSCs derived from human PC-3 cell line. This study may propose PLAC-1 as a potential target in targeted therapies, which should be confirmed through further studies.

Lipid metabolism dynamics in cancer stem cells: potential targets for cancers

Cancer stem cells (CSCs) represent a small subset of heterogeneous cells within tumors that possess the ability to self-renew and initiate tumorigenesis. They serve as potential drivers for tumor initiation, metastasis, recurrence, and drug resistance. Recent research has demonstrated that the stemness preservation of CSCs is heavily reliant on their unique lipid metabolism alterations, enabling them to maintain their own environmental homeostasis through various mechanisms. The primary objectives involve augmenting intracellular fatty acid (FA) content to bolster energy supply, promoting β-oxidation of FA to optimize energy utilization, and elevating the mevalonate (MVA) pathway for efficient cholesterol synthesis. Additionally, lipid droplets (LDs) can serve as alternative energy sources in the presence of glycolysis blockade in CSCs, thereby safeguarding FA from peroxidation. Furthermore, the interplay between autophagy and lipid metabolism facilitates rapid adaptation of CSCs to the harsh microenvironment induced by chemotherapy. In this review, we comprehensively review recent studies pertaining to lipid metabolism in CSCs and provide a concise overview of the indispensable role played by LDs, FA, cholesterol metabolism, and autophagy in maintaining the stemness of CSCs.

Sorted-Cell Sequencing on HCC Specimens Reveals EPS8L3 as a Key Player in CD24/CD13/EpCAM-Triple Positive, Stemness-Related HCC Cells

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is a heterogeneous cancer with varying levels of liver tumor initiating or cancer stem cells in the tumors. We aimed to investigate the expression of different liver cancer stem cell (LCSC) markers in human HCCs and identify their regulatory mechanisms in stemness-related cells.

METHODS

We used an unbiased, single-marker sorting approach by flow cytometry, fluorescence-activated cell sorting, and transcriptomic analyses on HCC patients' resected specimens. Knockdown approach was used, and relevant functional assays were conducted on the identified targets of interest.

RESULTS

Flow cytometry on a total of 60 HCC resected specimens showed significant heterogeneity in the expression of LCSC markers, with CD24, CD13, and EpCAM mainly contributing to this heterogeneity. Concomitant expression of CD24, CD13, and EpCAM was detected in 32 HCC samples, and this was associated with advanced tumor stages. Transcriptomic sequencing on the HCC cells sorted for these individual markers identified epidermal growth factor receptor kinase substrate 8-like protein 3 (EPS8L3) as a common gene associated with the 3 markers and was functionally validated in HCC cells. Knocking down EPS8L3 suppressed the expression of all 3 markers. To search for the upstream regulation of EPS8L3, we found SP1 bound to EPS8L3 promoter to drive EPS8L3 expression. Furthermore, using Akt inhibitor MK2206, we showed that Akt signaling-driven SP1 drove the expression of the 3 LCSC markers.

CONCLUSIONS

Our findings suggest that Akt signaling-driven SP1 promotes EPS8L3 expression, which is critical in maintaining the downstream expression of CD24, CD13, and EpCAM. The findings provide insight into potential LCSC-targeting therapeutic strategies.

Iron metabolism: backfire of cancer cell stemness and therapeutic modalities

Cancer stem cells (CSCs), with their ability of self-renewal, unlimited proliferation, and multi-directional differentiation, contribute to tumorigenesis, metastasis, recurrence, and resistance to conventional therapy and immunotherapy. Eliminating CSCs has long been thought to prevent tumorigenesis. Although known to negatively impact tumor prognosis, research revealed the unexpected role of iron metabolism as a key regulator of CSCs. This review explores recent advances in iron metabolism in CSCs, conventional cancer therapies targeting iron biochemistry, therapeutic resistance in these cells, and potential treatment options that could overcome them. These findings provide important insights into therapeutic modalities against intractable cancers.

β-hydroxybutyrate inhibits malignant phenotypes of prostate cancer cells through β-hydroxybutyrylation of indoleacetamide-N-methyltransferase

BACKGROUND

Prostate cancer (PCa) is one of the most prevalent cancers in men and is associated with high mortality and disability rates. β-hydroxybutyrate (BHB), a ketone body, has received increasing attention for its role in cancer. However, its role in PCa remains unclear. This study aimed to explore the mechanism and feasibility of BHB as a treatment alternative for PCa.

METHODS

Colony formation assay, flow cytometry, western blot assay, and transwell assays were performed to determine the effect of BHB on the proliferation and metastasis of PCa cells. Tumor sphere formation and aldehyde dehydrogenase assays were used to identify the impact of BHB or indoleacetamide-N-methyltransferase (INMT) on the stemness of PCa cells. N6-methyladenosine (m6A)-meRIP real-time reverse transcription polymerase chain reaction and dual luciferase assays were conducted to confirm INMT upregulation via the METTL3-m6A pathway. Co-IP assay was used to detect the epigenetic modification of INMT by BHB-mediated β-hydroxybutyrylation (kbhb) and screen enzymes that regulate INMT kbhb. Mouse xenograft experiments demonstrated the antitumor effects of BHB in vivo.

RESULTS

BHB can inhibit the proliferation, migration, and invasion of PCa cells by suppressing their stemness. Mechanistically, INMT, whose expression is upregulated by the METTL3-m6A pathway, was demonstrated to be an oncogenic gene that promotes the stem-like characteristics of PCa cells. BHB can suppress the malignant phenotypes of PCa by kbhb of INMT, which in turn inhibits INMT expression.

CONCLUSIONS

Our findings indicate a role of BHB in PCa metabolic therapy, thereby suggesting an epigenetic therapeutic strategy to target INMT in aggressive PCa.

TRIAL REGISTRATION

Not applicable.

Current Advances of Nanomaterial-Based Oral Drug Delivery for Colorectal Cancer Treatment

Colorectal cancer (CRC) is a common malignant tumor, and traditional treatments include surgical resection and radiotherapy. However, local recurrence, distal metastasis, and intestinal obstruction are significant problems. Oral nano-formulation is a promising treatment strategy for CRC. This study introduces physiological and environmental factors, the main challenges of CRC treatment, and the need for a novel oral colon-targeted drug delivery system (OCDDS). This study reviews the research progress of controlled-release, responsive, magnetic, targeted, and other oral nano-formulations in the direction of CRC treatment, in addition to the advantages of oral colon-targeted nano-formulations and concerns about the oral delivery of related therapeutic agents to inspire related research.

Production of a Ribosome-Displayed Mouse scFv Antibody Against CD133, Analysis of Its Molecular Docking, and Molecular Dynamic Simulations of Their Interactions

The pentaspan transmembrane glycoprotein CD133, prominin-1, is expressed in cancer stem cells in many tumors and is promising as a novel target for the delivery of cytotoxic drugs to cancer-initiating cells. In this study, we prepared a mouse library of single-chain variable fragment (scFv) antibodies using mRNAs isolated from mice immunized with the third extracellular domain of a recombinant CD133 (D-EC3). First, the scFvs were directly exposed to D-EC3 to select a new specific scFv with high affinity against CD133 using the ribosome display method. Then, the selected scFv was characterized by the indirect enzyme-linked immunosorbent assay (ELISA), immunocytochemistry (ICC), and in silico analyses included molecular docking and molecular dynamics simulations. Based on ELISA results, scFv 2 had a higher affinity for recombinant CD133, and it was considered for further analysis. Next, the immunocytochemistry and flow cytometry experiments confirmed that the obtained scFv could bind to the CD133 expressing HT-29 cells. Furthermore, the results of in silico analysis verified the ability of the scFv 2 antibody to bind and detect the D-EC3 antigen through key residues employed in antigen-antibody interactions. Our results suggest that ribosome display could be applied as a rapid and valid method for isolation of scFv with high affinity and specificity. Also, studying the mechanism of interaction between CD133's scFv and D-EC3 with two approaches of experimental and in silico analysis has potential importance for the design and development of antibody with improved properties.

Pharmacodynamic effects of the PARP inhibitor talazoparib (MDV3800, BMN 673) in patients with BRCA-mutated advanced solid tumors

PURPOSE

Talazoparib is an inhibitor of the poly (ADP-ribose) polymerase (PARP) family of enzymes and is FDA-approved for patients with (suspected) deleterious germline BRCA1/2-mutated, HER2‑negative, locally advanced or metastatic breast cancer. Because knowledge of the pharmacodynamic (PD) effects of talazoparib in patients has been limited to studies of PARP enzymatic activity (PARylation) in peripheral blood mononuclear cells, we developed a study to assess tumoral PD response to talazoparib treatment (NCT01989546).

METHODS

We administered single-agent talazoparib (1 mg/day) orally in 28-day cycles to adult patients with advanced solid tumors harboring (suspected) deleterious BRCA1 or BRCA2 mutations. The primary objective was to examine the PD effects of talazoparib; the secondary objective was to determine overall response rate (ORR). Tumor biopsies were mandatory at baseline and post-treatment on day 8 (optional at disease progression). Biopsies were analyzed for PARylation, DNA damage response (γH2AX), and epithelial‒mesenchymal transition.

RESULTS

Nine patients enrolled in this trial. Four of six patients (67%) evaluable for the primary PD endpoint exhibited a nuclear γH2AX response on day 8 of treatment, and five of six (83%) also exhibited strong suppression of PARylation. A transition towards a more mesenchymal phenotype was seen in 4 of 6 carcinoma patients, but this biological change did not affect γH2AX or PAR responses. The ORR was 55% with the five partial responses lasting a median of six cycles.

CONCLUSION

Intra-tumoral DNA damage response and inhibition of PARP enzymatic activity were confirmed in patients with advanced solid tumors harboring BRCA1/2 mutations after 8 days of talazoparib treatment.

FBP1 inhibits NSCLC stemness by promoting ubiquitination of Notch1 intracellular domain and accelerating degradation

The existence of cancer stem cells is widely acknowledged as the underlying cause for the challenging curability and high relapse rates observed in various tumor types, including non-small cell lung cancer (NSCLC). Despite extensive research on numerous therapeutic targets for NSCLC treatment, the strategies to effectively combat NSCLC stemness and achieve a definitive cure are still not well defined. The primary objective of this study was to examine the underlying mechanism through which Fructose-1,6-bisphosphatase 1 (FBP1), a gluconeogenic enzyme, functions as a tumor suppressor to regulate the stemness of NSCLC. Herein, we showed that overexpression of FBP1 led to a decrease in the proportion of CD133-positive cells, weakened tumorigenicity, and decreased expression of stemness factors. FBP1 inhibited the activation of Notch signaling, while it had no impact on the transcription level of Notch 1 intracellular domain (NICD1). Instead, FBP1 interacted with NICD1 and the E3 ubiquitin ligase FBXW7 to facilitate the degradation of NICD1 through the ubiquitin-proteasome pathway, which is independent of the metabolic enzymatic activity of FBP1. The aforementioned studies suggest that targeting the FBP1-FBXW7-NICD1 axis holds promise as a therapeutic approach for addressing the challenges of NSCLC recurrence and drug resistance.

Astragalus polysaccharide ameliorates CD8+ T cell dysfunction through STAT3/Gal-3/LAG3 pathway in inflammation-induced colorectal cancer

Chronic inflammation can promote cancer development as observed in inflammation-induced colorectal cancer (CRC). However, the poor treatment outcomes emphasize the need for effective treatment. Astragalus polysaccharide (APS), a vital component of the natural drug Astragalus, has anti-tumor effects by inhibiting cancer cell proliferation and enhancing immune function. In this study, we found that APS effectively suppressed CRC development through activating CD8+ T cells and reversing its inhibitory state in the tumor microenvironment (TME) of AOM/DSS inflammation-induced CRC mice. Network pharmacology and clinical databases suggested that the STAT3/ Galectin-3(Gal-3)/LAG3 pathway might be APS's potential target for treating CRC and associated with CD8+ T cell dysfunction. In vivo experiments showed that APS significantly reduced phosphorylated STAT3 and Gal-3 levels in tumor cells, as well as LAG3 in CD8+ T cells. Co-culture experiments with MC38 and CD8+ T cells demonstrated that APS decreased the expression of co-inhibitory receptor LAG3 in CD8+ T cells by targeting STAT3/Gal-3 in MC38 cells. Mechanism investigations revealed that APS specifically improved CD8+ T cell function through modulation of the STAT3/Gal-3/LAG3 pathway to inhibit CRC development, providing insights for future clinical development of natural anti-tumor drugs and immunotherapies as a novel strategy combined with immune checkpoint inhibitors (ICIs).

Zebrafish xenograft as a tool for the study of colorectal cancer: a review

Colorectal cancer (CRC) is the second leading cause of cancer-related death, mostly due to metastatic disease and the fact that many patients already show signs of metastasis at the time of first diagnosis. Current CRC therapies negatively impact patients' quality of life and have little to no effect on combating the tumor once the dissemination has started. Danio rerio (zebrafish) is a popular animal model utilized in cancer research. One of its main advantages is the ease of xenograft transplantation due to the fact that zebrafish larvae lack the adaptative immune system, guaranteeing the impossibility of rejection. In this review, we have presented the many works that choose zebrafish xenograft as a tool for the study of CRC, highlighting the methods used as well as the promising new therapeutic molecules that have been identified due to this animal model.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

Investigating the Diagnostic and Therapeutic Potential of SREBF2-Related Lipid Metabolism Genes in Colon Cancer

Purpose

Colon cancer is one of the leading causes of death worldwide, and screening of effective molecular markers for the diagnosis is prioritised for prevention and treatment. This study aimed to investigate the diagnostic and predictive potential of genes related to the lipid metabolism pathway, regulated by a protein called sterol-regulatory element-binding transcription Factor 2 (SREBF2), for colon cancer and patient outcomes.

Methods

We used machine-learning algorithms to identify key genes associated with SREBF2 in colon cancer based on a public database. A nomogram was created to assess the diagnostic value of these genes and validated in the Cancer Genome Atlas. We also analysed the relationship between these genes and the immune microenvironment of colon tumours, as well as the correlation between gene expression and clinicopathological characteristics and prognosis in the China Medical University (CMU) clinical cohort.

Results

Three genes, 7-dehydrocholesterol reductase (DHCR7), hydroxysteroid 11-beta dehydrogenase 2 (HSD11B2), and Ral guanine nucleotide dissociation stimulator-like 1 (RGL1), were identified as hub genes related to SREBF2 and colon cancer. Using the TCGA dataset, receiver operating characteristic curve analysis showed the area under the curve values of 0.943, 0.976, and 0.868 for DHCR7, HSD11B2, and RGL1, respectively. In the CMU cohort, SREBF2 and DHCR7 expression levels were correlated with TNM stage and tumour invasion depth (P < 0.05), and high DHCR7 expression was related to poor prognosis of colon cancer (P < 0.05). Furthermore, DHCR7 gene expression was positively correlated with the abundance of M0 and M1 macrophages and inversely correlated with the abundance of M2 macrophages, suggesting that the immune microenvironment may play a role in colon cancer surveillance. There was a correlation between SREBF2 and DHCR7 expression across cancers in the TCGA database.

Conclusion

This study highlights the potential of DHCR7 as a diagnostic marker and therapeutic target for colon cancer.

Targeting cancer stem cell plasticity in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer subtype with limited treatment options. Cancer stem cells (CSCs) are thought to play a crucial role in TNBC progression and resistance to therapy. CSCs are a small subpopulation of cells within tumors that possess self-renewal and differentiation capabilities and are responsible for tumor initiation, maintenance, and metastasis. CSCs exhibit plasticity, allowing them to switch between states and adapt to changing microenvironments. Targeting CSC plasticity has emerged as a promising strategy for TNBC treatment. This review summarizes recent advances in understanding the molecular mechanisms underlying CSC plasticity in TNBC and discusses potential therapeutic approaches targeting CSC plasticity.

Targeting ABCA12-controlled ceramide homeostasis inhibits breast cancer stem cell function and chemoresistance

Cancer stem cells (CSCs) drive tumor growth, metastasis, and chemoresistance. While emerging evidence suggests that CSCs have a unique dependency on lipid metabolism, the functions and regulation of distinct lipid species in CSCs remain poorly understood. Here, we developed a stem cell factor SOX9-based reporter for isolating CSCs in primary tumors and metastases of spontaneous mammary tumor models. Transcriptomic analyses uncover that SOX9high CSCs up-regulate the ABCA12 lipid transporter. ABCA12 down-regulation impairs cancer stemness and chemoresistance. Lipidomic analyses reveal that ABCA12 maintains cancer stemness and chemoresistance by reducing intracellular ceramide abundance, identifying a CSC-associated function of ABCA subfamily transporter. Ceramide suppresses cancer stemness by inhibiting the YAP-SOX9 signaling pathway in CSCs. Increasing ceramide levels in tumors enhances their sensitivity to chemotherapy and prevents the enrichment of SOX9high CSCs. In addition, SOX9high and ABCA12high cancer cells contribute to chemoresistance in human patient-derived xenografts. These findings identify a CSC-suppressing lipid metabolism pathway that can be exploited to inhibit CSCs and overcome chemoresistance.

Extirpating the cancer stem cell hydra: Differentiation therapy and Hyperthermia therapy for targeting the cancer stem cell hierarchy

Ever since the discovery of cancer stem cells (CSCs), they have progressively attracted more attention as a therapeutic target. Like the mythical hydra, this subpopulation of cells seems to contribute to cancer immortality, spawning more cells each time that some components of the cancer cell hierarchy are destroyed. Traditional modalities focusing on cancer treatment have emphasized apoptosis as a route to eliminate the tumor burden. A major problem is that cancer cells are often in varying degrees of dedifferentiation contributing to what is known as the CSCs hierarchy and cells which are known to be resistant to conventional therapy. Differentiation therapy is an experimental therapeutic modality aimed at the conversion of malignant phenotype to a more benign one. Hyperthermia therapy (HT) is a modality exploiting the changes induced in cells by the application of heat produced to aid in cancer therapy. While differentiation therapy has been successfully employed in the treatment of acute myeloid leukemia, it has not been hugely successful for other cancer types. Mounting evidence suggests that hyperthermia therapy may greatly augment the effects of differentiation therapy while simultaneously overcoming many of the hard-to-treat facets of recurrent tumors. This review summarizes the progress made so far in integrating hyperthermia therapy with existing modules of differentiation therapy. The focus is on studies related to the successful application of both hyperthermia and differentiation therapy when used alone or in conjunction for hard-to-treat cancer cell niche with emphasis on combined approaches to target the CSCs hierarchy.

Effect of red wheat, aleurone, and testa layers on colon cancer biomarkers, nitrosative stress, and gut microbiome composition in rats

We previously found greater reduction of colon cancer (CC) biomarkers for red wheat compared to white wheat regardless of refinement state. In the present study we examined whether the phenolic-rich aleurone and testa layers are drivers of chemoprevention by red wheat and their influence on gut microbiota composition using a 1,2-dimethylhydrazine-induced CC rat model. Rats were fed a low-fat diet (16% of energy as fat), high-fat diet (50% of energy as fat), or high-fat diet containing whole red wheat, refined red wheat, refined white wheat, or aleurone- or testa-enriched fractions for 12 weeks. Morphological markers (aberrant crypt foci, ACF) were assessed after methylene blue staining and biochemical markers (3-nitrotyrosine [3-NT], Dclk1) by immunohistochemical determination of staining positivity within aberrant crypts. Gut microbiota composition was evaluated from 16S rRNA gene sequencing of DNA extracted from cecal contents. Relative to the high-fat diet, the whole and refined red wheat, refined white wheat, and testa-enriched fraction decreased ACF, while only the refined red wheat and aleurone-enriched fraction decreased 3-NT. No significant differences were observed for Dclk1. An increase in microbial diversity was observed for the aleurone-enriched fraction (ACE index) and whole red wheat (Inverse Simpson Index). The diet groups significantly modified overall microbiome composition, including altered abundances of Lactobacillus, Mucispirillum, Phascolarctobacterium, and Blautia coccoides. These results suggest that red wheat may reduce CC risk through modifications to the gut microbiota and nitrosative stress, which may be due, in part, to the influence of dietary fiber and the phenolic-rich aleurone layer.

Screening and validation of the optimal panel of reference genes in colonic epithelium and relative cancer cell lines

Real-time quantitative polymerase chain reaction (RT-qPCR) is the most common method to determine mRNA expression, and Minimum Information for Publication of RT-qPCR Experiments (MIQE) proposes that a panel of reference genes for RT-qPCR is conducive to obtaining accurate results. This study aimed to screen and verify the optimal panel of reference genes in colorectal cancer (CRC) and normal colonic cell lines. In the study, eight candidate reference genes (GAPDH, ACTB, 18S, PPIA, B2M, SDHA, GUSB, and YWHAZ) were selected for RT-qPCR to detect their expression in NCM460, HT29, HCT116, SW480, SW620, DLD-1, LOVO and RKO cell lines. The stability of reference genes and the optimal panel were evaluated by geNorm, NormFinder, and BestKeeper software. As results, the expression levels of candidate reference genes differed in the colonic epithelial cell lines, and the number of optimal panel of reference genes is two. B2M and YWHAZ were the two most stable reference genes for NCM460, HCT116, SW620, LOVO, and RKO cell lines, while only one of B2M and YWHAZ was most stable in HT29 and SW480 cells. In DLD-1 cells, the stability of B2M and YWHAZ ranked 3rd and 6th, PPIA and GUSB were the most stable two. Furthermore, the YWHZA + B2M performed smaller intragroup differences than other panel or single reference gene. In conclusion, this study indicates the optimal panel of reference genes is YWHZA + B2M for the NCM460, HCT116, SW620, LOVO, RKO, SW480, and HT29 cell lines, but it is PPIA + GUSB in DLD-1 cell lines.

Unraveling the Role of Molecular Profiling in Predicting Treatment Response in Stage III Colorectal Cancer Patients: Insights from the IDEA International Study

BACKGROUND

This study aimed to investigate the molecular profiles of 237 stage III CRC patients from the international IDEA study. It also sought to correlate these profiles with Toll-like and vitamin D receptor polymorphisms, clinicopathological and epidemiological characteristics, and patient outcomes.

METHODS

Whole Exome Sequencing and PCR-RFLP on surgical specimens and blood samples, respectively, were performed to identify molecular profiling and the presence of Toll-like and vitamin D polymorphisms. Bioinformatic analysis revealed mutational status.

RESULTS

Among the enrolled patients, 63.7% were male, 66.7% had left-sided tumors, and 55.7% received CAPOX as adjuvant chemotherapy. Whole exome sequencing identified 59 mutated genes in 11 different signaling pathways from the Kyoto Encyclopedia of Genes and Genomes (KEGG) CRC panel. On average, patients had 8 mutated genes (range, 2-21 genes). Mutations in ARAF and MAPK10 emerged as independent prognostic factors for reduced DFS (p = 0.027 and p < 0.001, respectively), while RAC3 and RHOA genes emerged as independent prognostic factors for reduced OS (p = 0.029 and p = 0.006, respectively). Right-sided tumors were also identified as independent prognostic factors for reduced DFS (p = 0.019) and OS (p = 0.043). Additionally, patients with tumors in the transverse colon had mutations in genes related to apoptosis, PIK3-Akt, Wnt, and MAPK signaling pathways.

CONCLUSIONS

Molecular characterization of tumor cells can enhance our understanding of the disease course. Mutations may serve as promising prognostic biomarkers, offering improved treatment options. Confirming these findings will require larger patient cohorts and international collaborations to establish correlations between molecular profiling, clinicopathological and epidemiological characteristics and clinical outcomes.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

Effect of photothermal and photodynamic therapy with cobalt ferrite superparamagnetic nanoparticles loaded with ICG and PpIX on cancer stem cells in MDA-MB-231 and A375 cell lines

BACKGROUND

Cancer cells are resistant to treatments such as chemotherapy and radiotherapy due to their characteristics such as self-renewal, high proliferation and other resistance mechanisms. To overcome this resistance, we combined a light-based treatment with nanoparticles to get advantage of both PDT and PTT in order to increase efficiency and beater outcome.

METHODS AND MATERIAL

After synthesis and characterization of CoFe2O4@citric@PEG@ICG@ PpIX NPs, their dark cytotoxicity concentration was determined with MTT assay. Then light-base treatments were performed by two different light source for MDA-MB-231 and A375 cell lines. After treatment, the results were evaluated 48 h and 24 h after treatment by MTT assay and flow cytometry. Among CSCs defined markers, CD44, CD24 and CD133 are the most widely-used markers in CSC research and are also therapeutic targets in cancers. So we used proper antibodies to detect CSCs. Then indexes like ED50, synergism defined to evaluated the treatment.

RESULTS

ROS production and temperature increase have a direct relationship with exposure time. In both cell lines, the death rate in combinational treatment (PDT/PTT) is higher than single treatment and the amount of cells with CD44+CD24- and CD133+CD44+ markers has decreased. According to the synergism index, conjugated NPs show a high efficiency in use in light-based treatments. This index was higher in cell line MDA-MB-231 than A375. And the ED50 is proof of the high sensitivity of A375 cell line compared to MDA-MB-231 in PDT and PTT.

CONCLUSION

Conjugated NPs along with combined photothermal and photodynamic therapies may play an important role in eradication CSCs.

Cancer Stem-Like Cells-Oriented Surface Self-Assembly to Conquer Radioresistance

Cancer stem-like cells (CSCs), capable of indefinite self-renewal and differentiation, are considered to be the root cause of tumor radiotherapy (RT) resistance. However, the CSCs-targeted therapy still remains to be a great challenge because they are commonly located in the deep tumor making drugs hard to approach, and their hypoxic and acidic niche can further aggravate radioresistance. Herein, based on the finding that hypoxic CSCs highly express carbonic anhydrase IX (CAIX) on the cell membrane, a CAIX-targeted induced in situ self-assembly system on the surface of CSC is reported to overcome hypoxic CSC-mediated radioresistance. Via the sequential processes of "monomer release-target accumulation-surface self-assembly", the constructed peptide-based drug delivery system (CA-Pt) exhibits the advantages of deep penetration, amplified CAIX inhibition, and enhanced cellular uptake, which greatly relieves the hypoxic and acidic microenvironment to promote the hypoxic CSC differentiation and combines with platinum to boost the RT-inducing DNA damage. In both lung cancer tumor mouse and zebrafish embryo models, CA-Pt treatment can effectively assist RT in suppressing tumor growth and preventing tumor invasion and metastasis. This study uses a surface-induced self-assembly strategy to differentiate hypoxic CSCs, which may provide a universal treatment strategy for overcoming tumor radioresistance.

Induction of promyelocytic leukemia zinc finger protein by miR-200c-3p restores sensitivity to anti-androgen therapy in androgen-refractory prostate cancer and inhibits the cancer progression via down-regulation of integrin α3β4

PURPOSE

Androgen-refractory prostate cancer (ARPC) is one of the aggressive human cancers with metastatic capacity and resistance to androgen deprivation therapy (ADT). The present study investigated the genes responsible for ARPC progression and ADT resistance, and their regulatory mechanisms.

METHODS

Transcriptome analysis, co-immunoprecipitation, confocal microscopy, and FACS analysis were performed to determine differentially-expressed genes, integrin α3β4 heterodimer, and cancer stem cell (CSC) population. miRNA array, 3'-UTR reporter assay, ChIP assay, qPCR, and immunoblotting were used to determine differentially-expressed microRNAs, their binding to integrin transcripts, and gene expressions. A xenograft tumor model was used to assess tumor growth and metastasis.

RESULTS

Metastatic ARPC cell lines (PC-3 and DU145) exhibiting significant downregulation of ZBTB16 and AR showed significantly upregulated ITGA3 and ITGB4. Silencing either one of the integrin α3β4 heterodimer significantly suppressed ARPC survival and CSC population. miRNA array and 3'-UTR reporter assay revealed that miR-200c-3p, the most strongly downregulated miRNA in ARPCs, directly bound to 3'-UTR of ITGA3 and ITGB4 to inhibit the gene expression. Concurrently, miR-200c-3p also increased PLZF expression, which, in turn, inhibited integrin α3β4 expression. Combination treatment with miR-200c-3p mimic and AR inhibitor enzalutamide showed synergistic inhibitory effects on ARPC cell survival in vitro and tumour growth and metastasis of ARPC xenografts in vivo, and the combination effect was greater than the mimic alone.

CONCLUSION

This study demonstrated that miR-200c-3p treatment of ARPC is a promising therapeutic approach to restore the sensitivity to anti-androgen therapy and inhibit tumor growth and metastasis.

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.

Molecular Mechanisms of Tumor Cell Stemness Modulation during Formation of Spheroids

Cancer stem cells (CSCs), their properties and interaction with microenvironment are of interest in modern medicine and biology. There are many studies on the emergence of CSCs and their involvement in tumor pathogenesis. The most important property inherent to CSCs is their stemness. Stemness combines ability of the cell to maintain its pluripotency, give rise to differentiated cells, and interact with environment to maintain a balance between dormancy, proliferation, and regeneration. While adult stem cells exhibit these properties by participating in tissue homeostasis, CSCs behave as their malignant equivalents. High tumor resistance to therapy, ability to differentiate, activate angiogenesis and metastasis arise precisely due to the stemness of CSCs. These cells can be used as a target for therapy of different types of cancer. Laboratory models are needed to study cancer biology and find new therapeutic strategies. A promising direction is three-dimensional tumor models or spheroids. Such models exhibit properties resembling stemness in a natural tumor. By modifying spheroids, it becomes possible to investigate the effect of therapy on CSCs, thus contributing to the development of anti-tumor drug test systems. The review examines the niche of CSCs, the possibility of their study using three-dimensional spheroids, and existing markers for assessing stemness of CSCs.

Natural Compounds Targeting the Autophagy Pathway in the Treatment of Colorectal Cancer

Autophagy is a highly conserved intracellular degradation pathway by which misfolded proteins or damaged organelles are delivered in a double-membrane vacuolar vesicle and finally degraded by lysosomes. The risk of colorectal cancer (CRC) is high, and there is growing evidence that autophagy plays a critical role in regulating the initiation and metastasis of CRC; however, whether autophagy promotes or suppresses tumor progression is still controversial. Many natural compounds have been reported to exert anticancer effects or enhance current clinical therapies by modulating autophagy. Here, we discuss recent advancements in the molecular mechanisms of autophagy in regulating CRC. We also highlight the research on natural compounds that are particularly promising autophagy modulators for CRC treatment with clinical evidence. Overall, this review illustrates the importance of autophagy in CRC and provides perspectives for these natural autophagy regulators as new therapeutic candidates for CRC drug development.

Emerging Role of NRF2 Signaling in Cancer Stem Cell Phenotype

Cancer stem cells (CSCs) are a small population of tumor cells characterized by self-renewal and differentiation capacity. CSCs are currently postulated as the driving force that induces intra-tumor heterogeneity leading to tumor initiation, metastasis, and eventually tumor relapse. Notably, CSCs are inherently resistant to environmental stress, chemotherapy, and radiotherapy due to high levels of antioxidant systems and drug efflux transporters. In this context, a therapeutic strategy targeting the CSC-specific pathway holds a promising cure for cancer. NRF2 (nuclear factor erythroid 2-like 2; NFE2L2) is a master transcription factor that regulates an array of genes involved in the detoxification of reactive oxygen species/electrophiles. Accumulating evidence suggests that persistent NRF2 activation, observed in multiple types of cancer, supports tumor growth, aggressive malignancy, and therapy resistance. Herein, we describe the core properties of CSCs, focusing on treatment resistance, and review the evidence that demonstrates the roles of NRF2 signaling in conferring unique properties of CSCs and the associated signaling pathways.

Targeted degradation of ABCG2 for reversing multidrug resistance by hypervalent bispecific gold nanoparticle-anchored aptamer chimeras

Hypervalent bispecific gold nanoparticle-anchored aptamer chimeras (AuNP-APTACs) were designed as a new tool of lysosome-targeting chimeras (LYTACs) for efficient degradation of the ATP-binding cassette, subfamily G, isoform 2 protein (ABCG2) to reverse multidrug resistance (MDR) of cancer cells. The AuNP-APTACs could effectively increase the accumulation of drugs in drug-resistant cancer cells and provide comparable efficacy to small-molecule inhibitors. Thus, this new strategy provides a new way to reverse MDR, holding great promise in cancer therapy.

A curcumin analogue GO-Y030 depletes cancer stem cells by inhibiting the interaction between the HSP70/HSP40 complex and its substrates

Cancer stem cells (CSCs) are proposed to be involved in tumor initiation and play important roles in cancer relapse, metastasis, and drug resistance. Therefore, the targeting of CSCs has potential for effective anticancer therapies. Curcumin is one of the most widely characterized phytochemicals with tumor-suppressive potential. GO-Y030 is a novel curcumin analogue exhibiting a much stronger growth-inhibitory effect than curcumin. In the present study, we verified the potency of GO-Y030 against a CSC population. We observed that GO-Y030 suppressed CSC sphere-forming ability in several cancer cell lines. Interestingly, a specific inhibitor of heat shock protein (HSP) 70 also exhibited effects similar to GO-Y030 (i.e. inhibition of CSC sphere formation and upregulation of HSP70 and HSP40 protein expression), suggesting that HSP70 and/or HSP40 might be target molecules of GO-Y030. We then performed an in vitro HSP70/HSP40-mediated refolding activity assay and observed that chaperone activity was efficiently inhibited by GO-Y030. Finally, we performed a substrate-binding assay to show that GO-Y030 reduced the binding of both HSP70 and HSP40 with their substrates. HSPs prevent denaturation or unfolding of client proteins under stressful conditions such as high temperature. Because CSCs by nature adapt to various stresses by reinforcing protein-folding activity, the function of HSP70/HSP40 is important for the maintenance of CSC population. Our data suggest that GO-Y030 may impair stress tolerance in CSCs by inhibiting the interaction of HSP70/HSP40 with their substrate proteins and disrupting the function of HSP70/HSP40, thereby contributing to a reduction of the CSC population.

Cancer Stem Cells and Their Therapeutic Usage

Cancer stem cells (CSC) have unique characteristics which include self-renewal, multi-directional differentiation capacity, quiescence/dormancy, and tumor-forming capability. These characteristics are referred to as the "stemness" properties. Tumor microenvironment contributes to CSC survival, function, and remaining them in an undifferentiated state. CSCs can form malignant tumors with heterogeneous phenotypes mediated by the tumor microenvironment. Therefore, the crosstalk between CSCs and tumor microenvironment can modulate tumor heterogeneity. CSCs play a crucial role in several biological processes, epithelial-mesenchymal transition (EMT), autophagy, and cellular stress response. In this chapter, we focused characteristics of cancer stem cells, reprogramming strategies cells into CSCs, and then we highlighted the contribution of CSCs to therapy resistance and cancer relapse and their potential of therapeutic targeting of CSCs.

Olfactomedin 4 associates with expression of differentiation markers but not with properties of cancer stemness, EMT nor metastatic spread in colorectal cancer

Tumor stem cells play a pivotal role in carcinogenesis and metastatic spread in colorectal cancer (CRC). Olfactomedin 4 (OLFM4) is co-expressed with the established stem cell marker leucine-rich repeat-containing G protein-coupled receptor 5 at the bottom of intestinal crypts and has been suggested as a surrogate for cancer stemness and a biomarker in gastrointestinal tumors associated with prognosis. Therefore, it was the aim of the present study to clarify whether OLFM4 is involved in carcinogenesis and metastatic spread in CRC. We used a combined approach of functional assays using forced OLFM4 overexpression in human CRC cell lines, xenograft mice, and an immunohistochemical approach using patient tissues to investigate the impact of OLFM4 on stemness, canonical Wnt signaling, properties of metastasis and differentiation as well as prognosis. OLFM4 expression correlated weakly with tumor grade in one patient cohort (metastasis collection: p = 0.05; pooled analysis of metastasis collection and survival collection: p = 0.19) and paralleled the expression of differentiation markers (FABP2, MUC2, and CK20) (p = 0.002) but did not correlate with stemness-associated markers. Further analyses in CRC cells lines as well as xenograft mice including forced overexpression of OLFM4 revealed that OLFM4 neither altered the expression of markers of stemness nor epithelial-mesenchymal transition, nor did OLFM4 itself drive proliferation, migration, or colony formation, which are all prerequisites of carcinogenesis and tumor progression. In line with this, we found no significant correlation between OLFM4 expression, metastasis, and patient survival. In summary, expression of OLFM4 in human CRC seems to be characteristic of differentiation marker expression in CRC but is not a driver of carcinogenesis nor metastatic spread.

Zinc finger and SCAN domain containing 1, ZSCAN1, is a novel stemness-related tumor suppressor and transcriptional repressor in breast cancer targeting TAZ

Introduction

Cancer stem cells (CSCs) targeted therapy holds the potential for improving cancer management; identification of stemness-related genes in CSCs is necessary for its development.

Methods

The Cancer Genome Atlas (TCGA) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) datasets were used for survival analysis. ZSCAN1 correlated genes was identified by Spearman correlation analysis. Breast cancer stem-like cells (BCSLCs) were isolated by sorting CD44+CD24- cells from suspension cultured breast cancer (BC) spheroids. The sphere-forming capacity and sphere- and tumor-initiating capacities were determined by sphere formation and limiting dilution assays. The relative gene expression was determined by qRT-PCR, western blot. Lentivirus system was used for gene manipulation. Nuclear run-on assay was employed to examine the levels of nascent mRNAs. DNA pull-down and Chromatin immunoprecipitation (ChIP) assays were used for determining the interaction between protein and target DNA fragments. Luciferase reporter assay was used for evaluating the activity of the promoter.

Results and discussion

ZSCAN1 is aberrantly suppressed in BC, and this suppression indicates a bad prognosis. Ectopic expression of ZSCAN1 inhibited the proliferation, clonogenicity, and tumorigenicity of BC cells. ZSCAN1-overexpressing BCSLCs exhibited weakened stemness properties. Normal human mammary epithelial (HMLE) cells with ZSCAN1 depletion exhibited enhanced stemness properties. Mechanistic studies showed that ZSCAN1 directly binds to -951 ~ -925bp region of WWTR1 (encodes TAZ) promoter, inhibits WWTR1 transcription, thereby inhibiting the stemness of BCSCs. Our work thus revealed ZSCAN1 as a novel stemness-related tumor suppressor and transcriptional repressor in BC.

The Role of Tumor Microenvironment in Regulating the Plasticity of Osteosarcoma Cells

Osteosarcoma (OS) is a malignancy that is becoming increasingly common in adolescents. OS stem cells (OSCs) form a dynamic subset of OS cells that are responsible for malignant progression and chemoradiotherapy resistance. The unique properties of OSCs, including self-renewal, multilineage differentiation and metastatic potential, 149 depend closely on their tumor microenvironment. In recent years, the likelihood of its dynamic plasticity has been extensively studied. Importantly, the tumor microenvironment appears to act as the main regulatory component of OS cell plasticity. For these reasons aforementioned, novel strategies for OS treatment focusing on modulating OS cell plasticity and the possibility of modulating the composition of the tumor microenvironment are currently being explored. In this paper, we review recent studies describing the phenomenon of OSCs and factors known to influence phenotypic plasticity. The microenvironment, which can regulate OSC plasticity, has great potential for clinical exploitation and provides different perspectives for drug and treatment design for OS.

Mesenchymal stem cells derived from adipose accelerate the progression of colon cancer by inducing a MT-CAFs phenotype via TRPC3/NF-KB axis

Background

There is increasing evidence that mesenchymal stem cells (MSCs) help shape the tumor microenvironment and promote tumor progression, and ion channels might play a critical role in this process. The objective of the present study was to explore the function and mechanism of MT-CAFs on progression of colon cancer.

Methods

Here, a gene chip was used for a general analysis of gene expression changes in MSC-transformed CAF cells (MT-CAFs). Bioinformatic tool and western blot screened out the ion channel protein TRPC3 with significantly increased expression, and identify the function through two-photon microscope. The progression of cancer was detected via MTS, transwell and Wound Healing. ELISA deected the secretion of inflammation factors. TRPC3/NF-KB axis was identified by western blot and immunofluorescence.

Results

TRPC3 can caused calcium influx, which further activated the NF-KB signaling pathway. Knockdown or inhibition of TRPC3 in MSCs significantly reduced the activation of NF-KB, and decreased the growth, migration, and invasion of MT-CAFs. After TRPC3 knockdown, the ability of MT- CAFs to promote tumor migration and invasion was impaired. Conversely, the upregulation of TRPC3 expression in MT-CAFs had the opposite effect. In vivo, TRPC3 expressed on MSCs also contributed to the tumorigenesis and progression of cancer cells. In addition, the Oncomine and GEPIA databases showed that TRPC3 expression is higher in colon cancer tissues compared with normal colon tissues, and was positively correlated with the expression of the CAF genes alpha-smooth muscle (α-SMA/ACTA2) and fibroblast activation protein Alpha. The disease-free survival of patients with positive TRPC3 expression in MSCs was significantly shorter than those with negative expression.

Conclusions

These results indicate that TRPC3 expressed on MT-CAFs plays a critical role in tumor progression via the NF-KB signaling pathway, and is correlated with poor prognosis in colon cancer patients. Therefore, TRPC3 may be a novel therapeutic target for the treatment of colon cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03017-5.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

Dysregulated FOXM1 signaling in the regulation of cancer stem cells

Since the introduction of the cancer stem cell (CSC) paradigm, significant advances have been made in understanding the functional and biological plasticity of these elusive components in malignancies. Endowed with self-renewing abilities and multilineage differentiation potential, CSCs have emerged as cellular drivers of virtually all facets of tumor biology, including metastasis, tumor recurrence/relapse, and drug resistance. The functional and biological characteristics of CSCs, such as self-renewal, cell fate decisions, survival, proliferation, and differentiation are regulated by an array of extracellular factors, signaling pathways, and pluripotent transcriptional factors. Besides the well-characterized regulatory role of transcription factors OCT4, SOX2, NANOG, KLF4, and MYC in CSCs, evidence for the central role of Forkhead box transcription factor FOXM1 in the establishment, maintenance, and functions of CSCs is accumulating. Conventionally identified as a master regulator of the cell cycle, a comprehensive understanding of this molecule has revealed its multifarious oncogenic potential and uncovered its role in angiogenesis, invasion, migration, self-renewal, and drug resistance. This review compiles the large body of literature that has accumulated in recent years that provides evidence for the mechanisms by which FOXM1 expression promotes stemness in glioblastoma, breast, colon, ovarian, lung, hepatic, and pancreatic carcinomas. We have also compiled the data showing the association of stem cell mediators with FOXM1 using TCGA mRNA expression data. Further, the prognostic importance of FOXM1 and other stem cell markers is presented. The delineation of FOXM1-mediated regulation of CSCs can aid in the development of molecularly targeted pharmacological approaches directed at the selective eradication of CSCs in several human malignancies.

Cancer-associated fibroblasts promote the stemness and progression of renal cell carcinoma via exosomal miR-181d-5p

The mechanisms underlying the effects of cancer-associated fibroblasts (CAFs) on cancer stemness and tumor progression in renal cell carcinoma (RCC) have not been elucidated yet. In the present study, we found that the enrichment of CAFs was positively associated with tumor progression and cancer stemness in RCC. Further investigation revealed that CAFs could enhance cancer stemness through delivering exosomes to RCC cells, and miR-181d-5p was identified as the critical exosomal miRNA in CAF-secreted exosomes by small RNA sequencing and subsequent screening assays. Mechanistically, exosomal miR-181d-5p transferred from CAFs to RCC cells directly suppressed the expression of ring finger protein 43 (RNF43) and activated Wnt/β-catenin signaling pathway, thus promoted cancer stemness and tumor progression. Overexpression of RNF43 strongly suppressed stemness properties and the effects could be reverted by miR-181d-5p. Overall, our findings revealed a crucial mechanism by which CAF-secreted exosomal miRNAs to enhance cancer stemness and thus promote RCC progression, suggesting a new avenue based on CAF-secreted miRNAs for more effective targeted therapies.

D. P, C. M, M. LI, C. D, G. P, D. C, A. T, M. G, S. DF, M. T, V. V, G. S. Targeting epigenetic alterations in cancer stem cells

Oncogenes or tumor suppressor genes are rarely mutated in several pediatric tumors and some early stage adult cancers. This suggests that an aberrant epigenetic reprogramming may crucially affect the tumorigenesis of these tumors. Compelling evidence support the hypothesis that cancer stem cells (CSCs), a cell subpopulation within the tumor bulk characterized by self-renewal capacity, metastatic potential and chemo-resistance, may derive from normal stem cells (NSCs) upon an epigenetic deregulation. Thus, a better understanding of the specific epigenetic alterations driving the transformation from NSCs into CSCs may help to identify efficacious treatments to target this aggressive subpopulation. Moreover, deepening the knowledge about these alterations may represent the framework to design novel therapeutic approaches also in the field of regenerative medicine in which bioengineering of NSCs has been evaluated. Here, we provide a broad overview about: 1) the role of aberrant epigenetic modifications contributing to CSC initiation, formation and maintenance, 2) the epigenetic inhibitors in clinical trial able to specifically target the CSC subpopulation, and 3) epigenetic drugs and stem cells used in regenerative medicine for cancer and diseases.

WNT signaling and cancer stemness

Cancer stemness, defined as the self-renewal and tumor-initiation potential of cancer stem cells (CSCs), is a cancer biology property featuring activation of CSC signaling networks. Canonical WNT signaling through Frizzled and LRP5/6 receptors is transmitted to the β-catenin-TCF/LEF-dependent transcription machinery to up-regulate MYC, CCND1, LGR5, SNAI1, IFNG, CCL28, CD274 (PD-L1) and other target genes. Canonical WNT signaling causes expansion of rapidly cycling CSCs and modulates both immune surveillance and immune tolerance. In contrast, noncanonical WNT signaling through Frizzled or the ROR1/2 receptors is transmitted to phospholipase C, Rac1 and RhoA to control transcriptional outputs mediated by NFAT, AP-1 and YAP-TEAD, respectively. Noncanonical WNT signaling supports maintenance of slowly cycling, quiescent or dormant CSCs and promotes epithelial-mesenchymal transition via crosstalk with TGFβ (transforming growth factor-β) signaling cascades, while the TGFβ signaling network induces immune evasion. The WNT signaling network orchestrates the functions of cancer-associated fibroblasts, endothelial cells and immune cells in the tumor microenvironment and fine-tunes stemness in human cancers, such as breast, colorectal, gastric and lung cancers. Here, WNT-related cancer stemness features, including proliferation/dormancy plasticity, epithelial-mesenchymal plasticity and immune-landscape plasticity, will be discussed. Porcupine inhibitors, β-catenin protein-protein interaction inhibitors, β-catenin proteolysis targeting chimeras, ROR1 inhibitors and ROR1-targeted biologics are investigational drugs targeting WNT signaling cascades. Mechanisms of cancer plasticity regulated by the WNT signaling network are promising targets for therapeutic intervention; however, further understanding of context-dependent reprogramming trajectories might be necessary to optimize the clinical benefits of WNT-targeted monotherapy and applied combination therapy for patients with cancer.

Acquired semi-squamatization during chemotherapy suggests differentiation as a therapeutic strategy for bladder cancer

Cisplatin-based chemotherapy remains the primary treatment for unresectable and metastatic muscle-invasive bladder cancers (MIBCs). However, tumors frequently develop chemoresistance. Here, we established a primary and orthotopic MIBC mouse model with gene-edited organoids to recapitulate the full course of chemotherapy in patients. We found that partial squamous differentiation, called semi-squamatization, is associated with acquired chemoresistance in both mice and human MIBCs. Multi-omics analyses showed that cathepsin H (CTSH) is correlated with chemoresistance and semi-squamatization. Cathepsin inhibition by E64 treatment induces full squamous differentiation and pyroptosis, and thus specifically restrains chemoresistant MIBCs. Mechanistically, E64 treatment activates the tumor necrosis factor pathway, which is required for the terminal differentiation and pyroptosis of chemoresistant MIBC cells. Our study revealed that semi-squamatization is a type of lineage plasticity associated with chemoresistance, suggesting that differentiation via targeting of CTSH is a potential therapeutic strategy for the treatment of chemoresistant MIBCs.

Generation of 3D Spheroids Using a Thiol-Acrylate Hydrogel Scaffold to Study Endocrine Response in ER+ Breast Cancer

Culturing cancer cells in a three-dimensional (3D) environment better recapitulates in vivo conditions by mimicking cell-to-cell interactions and mass transfer limitations of metabolites, oxygen, and drugs. Recent drug studies have suggested that a high rate of preclinical and clinical failures results from mass transfer limitations associated with drug entry into solid tumors that 2D model systems cannot predict. Droplet microfluidic devices offer a promising alternative to grow 3D spheroids from a small number of cells to reduce intratumor heterogeneity, which is lacking in other approaches. Spheroids were generated by encapsulating cells in novel thiol–acrylate (TA) hydrogel scaffold droplets followed by on-chip isolation of single droplets in a 990- or 450-member trapping array. The TA hydrogel rapidly (∼35 min) polymerized on-chip to provide an initial scaffold to support spheroid development followed by a time-dependent degradation. Two trapping arrays were fabricated with 150 or 300 μm diameter traps to investigate the effect of droplet size and cell seeding density on spheroid formation and growth. Both trapping arrays were capable of ∼99% droplet trapping efficiency with ∼90% and 55% cellular encapsulation in trapping arrays containing 300 and 150 μm traps, respectively. The oil phase was replaced with media ∼1 h after droplet trapping to initiate long-term spheroid culturing. The growth and viability of MCF-7 3D spheroids were confirmed for 7 days under continuous media flow using a customized gravity-driven system to eliminate the need for syringe pumps. It was found that a minimum of 10 or more encapsulated cells are needed to generate a growing spheroid while fewer than 10 parent cells produced stagnant 3D spheroids. As a proof of concept, a drug susceptibility study was performed treating the spheroids with fulvestrant followed by interrogating the spheroids for proliferation in the presence of estrogen. Following fulvestrant exposure, the spheroids showed significantly less proliferation in the presence of estrogen, confirming drug efficacy.