Colorectal Cancer Stem Research Articles

Ribosome Biogenesis Alterations in Colorectal Cancer.

Many studies have focused on understanding the regulation and functions of aberrant protein synthesis in colorectal cancer (CRC), leaving the ribosome, its main effector, relatively underappreciated in CRC. The production of functional ribosomes is initiated in the nucleolus, requires coordinated ribosomal RNA (rRNA) processing and ribosomal protein (RP) assembly, and is frequently hyperactivated to support the needs in protein synthesis essential to withstand unremitting cancer cell growth. This elevated ribosome production in cancer cells includes a strong alteration of ribosome biogenesis homeostasis that represents one of the hallmarks of cancer cells. None of the ribosome production steps escape this cancer-specific dysregulation. This review summarizes the early and late steps of ribosome biogenesis dysregulations described in CRC cell lines, intestinal organoids, CRC stem cells and mouse models, and their possible clinical implications. We highlight how this cancer-related ribosome biogenesis, both at quantitative and qualitative levels, can lead to the synthesis of ribosomes favoring the translation of mRNAs encoding hyperproliferative and survival factors. We also discuss whether cancer-related ribosome biogenesis is a mere consequence of cancer progression or is a causal factor in CRC, and how altered ribosome biogenesis pathways can represent effective targets to kill CRC cells. The association between exacerbated CRC cell growth and alteration of specific steps of ribosome biogenesis is highlighted as a key driver of tumorigenesis, providing promising perspectives for the implementation of predictive biomarkers and the development of new therapeutic drugs.

The response of PIK3CA/KRAS-mutant colorectal cancer stem-like cells to RGD-peptide FraC produced by the strawberry anemone: A promising water-soluble peptide-based inhibitor of metastasis-driver gene CXCR4, stem cell regulatory genes and self-renewal

Colorectal cancer (CRC) is a stem cell-based disease. PIK3CA/KRAS-mutant CRC stem cells (CRCSCs) display high self-renewal, metastatic properties, high activity of PI3K and KRAS signaling pathways with chemoresistant phenotypes. Recently, RGD peptide (containing Arg-Gly-Asp motif)-based therapy of solid tumor cells has attracted much attention. However, little is known whether this method can target self-renewal capacity, key effectors of PI3K and KRAS signaling pathways such as metastasis-driver gene CXCR4 and stem cell regulatory genes with caspase-3 reactivation in CRCSCs overexpressing RGD-dependent integrins.The sea anemone Actinia fragacea produces a water-soluble RGD-peptide fragacea toxin C (FraC) suggesting the possible activity of FraC against PIK3CA/KRAS-mutant CRCSCs.Recombinant FraC was expressed via pET-28a(+)-FraC in E. coli and purified through affinity chromatography followed by performing SDS-PAGE and hemolytic activity assay. Next, PIK3CA/KRAS-mutant HCT-116 cells that serve as an attractive model for CRCSCs were treated with FraC. Thereafter, cell numbers, viability, proliferation, LDH activity, cytotoxicity index, CXCR4 and pluripotency network genes expression, self-renewal capacity, caspase-3 activity with apoptosis were evaluated. Caspase-1, -2, -3,…, -9 sequences were analyzed for RGD-binding motifs. FraC sequence and structure were also evaluated by bioinformatics software.FraC altered cellular morphology to round shapes and disrupted cell connections. 48 h post-treatment with 0.056˗ to 7.2 μM FraC resulted in 12 %–99 % and 8 %–97.6 % decreases in cell numbers and viabilities respectively and increased LDH activity by 0.2 %–66.7 % in a dose-dependent manner. The results of the cytotoxicity index showed that FraC induces significant toxicity on HCT-116 cells compared to PBMCs and Huvec cells. FraC dramatically decreased the expression of CXCR4 and pluripotency network genes Bmi-1, Sox-2, Oct-4 and Nanog followed by remarkable decreases in self-renewal capacity ranged from 91- to 0 colonies per well for 0.056˗ to 3.6 μM FraC after 2 weeks. Caspase-3 was found to contain an RGD-binding motif and its activity increased with increasing FraC concentrations followed by apoptosis induction. Potential RGD-binding motifs for FraC were also found in caspase-1, -7, -8 and -9.Unique advantages of FraC peptide, such as low molecular weight, water solubility, high sensitivity of CRC stem-like cells with more selective toxicity to this compound, targeting tumor cell membrane and self-renewal capacity along with the modulation of CXCR4 and stem cell regulatory genes as upstream and downstream effectors of undruggable PI3K and KRAS signaling pathways may open up avenues for FraC peptide-based therapy of PIK3CA/KRAS-mutant CRCSCs with lower toxicity on healthy cells.

TAp63\u03b1 targeting of Lgr5 mediates colorectal cancer stem cell properties and sulforaphane inhibition

Cancer stem cells (CSCs) have an established role in cancer progression and therapeutic resistance. The p63 proteins are important transcription factors which belong to the p53 family, but their function and mechanism in CSCs remain elusive. Here, we investigated the role of TAp63α in colorectal CSCs and the effects of sulforaphane on TAp63α. We found that TAp63α was upregulated in spheres with stem cell properties compared to the parental cells. Overexpression of TAp63α promoted self-renewal capacity and enhanced CSC markers expression in colorectal sphere-forming cells. Furthermore, we showed that TAp63α directly bound to the promoter region of Lgr5 to enhance its expression and activate its downstream β-catenin pathway. Functional experiments revealed that sulforaphane suppressed the stemness of colorectal CSCs both in vitro and in vivo. Upregulation of TAp63α attenuated the inhibitory effect of sulforaphane on colorectal CSCs, indicating the role of TAp63α in sulforaphane suppression of the stemness in colorectal cancer. The present study elucidated for the first time that TAp63α promoted CSCs through targeting Lgr5/β-catenin axis and participated in sulforaphane inhibition of the stem cell properties in colorectal cancer.

STAT3‐mediated gene expression in colorectal cancer cells‐derived cancer stem‐like tumorspheres

AbstractSTAT3 is a transcriptional factor involved in tumorigenesis and the initiation of cancer stemness property. However, the STAT3‐downstream regulatory gene expressions in the formation of colorectal cancer (CRC)‐derived tumorsphere is obscure. In this study, RNAseq was used to uncover the potential genes involved in the formation of colorectal HCT116‐ and HT29‐derived stem‐like tumorspheres, whereas HCT116 and HT29 overexpressed CD133. Furthermore, STAT3 was knockdowned and analyzed consequently by RNAseq for picking up the STAT3‐mediated genes associated with tumorspheres formation. Then, quantitative polymerase chain reaction was used for validating the expressions of selected driver genes in epidermal growth factor (EGF) treated‐ and in STAT3‐knockdowned HT29 cells. We found that 654 genes and 646 genes were upregulated in HCT116‐ and HT29‐derived tumorspheres, respectively. There were 103 genes simultaneously increased in both CRC tumorspheres, including, STAT3 selected as a driver gene by NetworkAnalyst (https://www.networkanalyst.ca/). Moreover, there were 139 genes downregulated in HT29shSTAT3 cells compared to HT29shLuc cells, 12 of the genes were overlapped with the overexpressed 103 genes from tumorspheres, including, NDRG1, ALDOC, BHLHE40, ATF3, C6orf223, JUND, ERRFI1, HK2, ITPKA, PLOD2, IDI1, and S100A14. Among them, BHLHE40, ATF3, ERRFI1, ITPKA, and S100A14 were validated and induced by EGF treatment, that were, otherwise, decreased in HT29shSTAT3 cells. We found and validated that STAT3 mediated the formation of CRC stemness tumorspheres, and STAT3‐downstram BHLHE40, ATF3, ERRFI1, ITPKA, and S100A14 may be involved in the stemness property.

Abstract 264: Long noncoding RNA LNC01534 regulates cancer stem cells in colorectal cancer

Abstract Introduction The clinical importance of cancer stem cells (CSCs) has been widely reported, and clinical studies targeting CSCs are in progress. Additionally, accumulating evidence suggests that long noncoding RNAs (lncRNAs) have essential roles in cancer initiation and progression, while deregulated lncRNA expression is found in a variety of cancer types. In this study, we focused on lncRNAs regulating CSCs in colorectal cancer (CRC). Objectives To identify the lncRNAs associated with CSCs and to evaluate their clinical relevance and function. Materials and Methods We separated CSCs and other cells in CRC using the ornithine decarboxylase (ODC) degron system to visualize CSCs based on the correlation between low proteasome activity and CSC properties. We performed comprehensive gene analysis comparing CSCs and other cells to identify a candidate lncRNA that regulates the stemness of CRC cells. Finally, we analyzed the clinical relevance and function of the lncRNA. Results The lncRNA LNC01534 showed high expression in CSCs compared with the level in other CRC cells. Using gene expression and clinical data from the Cancer Genome Atlas Project for CRC patients, we showed that LNC01534 was associated with overall survival in CRC. LNC01534 was also associated with overall survival and disease-free survival in 187 separate CRC samples. Functional studies revealed that the loss of LNC01534 function reduced proliferation and arrested the cell cycle in CRC cells. Furthermore, genes that underwent expression changes upon the knockdown of LNC01534 were evaluated by RNA-seq. This showed that the knockdown of LNC01534 affected the expression of genes related to endoplasmic reticulum (ER) stress and autophagy. Specifically, the expression levels of HSPA5, LC3-I, p62, and Beclin-1–genes related to ER stress and autophagy–increased upon suppressing LNC01534. Conclusions We demonstrated the clinical and biological relevance of LNC01534 in association with CSCs, and discovered the effect of LNC01534 on ER stress and autophagy to maintain stemness in CRC. Citation Format: Masahisa Ohtsuka, Wu Xin, Momoko Ichihara, Haruka Hirose, Hidekazu Takahashi, Chu Matsuda, Hiroki Akamatsu, Tsunekazu Mizushima, Yuichiro Doki, Hirofumi Yamamoto. Long noncoding RNA LNC01534 regulates cancer stem cells in colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 264.

CircAGFG1 drives metastasis and stemness in colorectal cancer by modulating YY1/CTNNB1

Colorectal cancer (CRC) is a common malignancy with high occurrence and mortality worldwide. In recent years, the overall survival rate of CRC patients has been improved because of the advances in early diagnosis and therapy. However, the prognosis of CRC patients at the advanced stage is still poor due to high recurrence rate and metastasis. The function of circular RNA (circRNA) ArfGAP with FG repeats 1 (circAGFG1) has been explored in non-small-cell lung cancer and triple-negative breast cancer. Nevertheless, its role in CRC is not clear. In this study, circAGFG1 was upregulated in CRC cell lines. CircAGFG1 silencing significantly suppressed cell proliferation, migration, invasion, and stemness, while promoted cell apoptosis in CRC. Meanwhile, we found that circAGFG1 also accelerated CRC tumor growth and metastasis in vivo. Importantly, circAGFG1 activated Wnt/β-catenin pathway through regulating CTNNB1. Afterwards, YY1 was found to transcriptionally activate CTNNB1. Furthermore, circAGFG1 directly sponged miR-4262 and miR-185-5p to upregulate YY1 expression. Eventually, rescue assays demonstrated that the effect of circAGFG1 silencing on CRC cell functions was observably reversed by upregulating YY1 or CTNNB1. In brief, our findings uncovered that circAGFG1 modulated YY1/CTNNB1 axis to drive metastasis and stemness in CRC by sponging miR-4262 and miR-185-5p.

A Preliminary Study of miR-144 Inhibiting the Stemness of Colon Cancer Stem Cells by Targeting Krüppel-Like Factor 4.

Colon cancer is a prevalent clinical malignant tumor of the digestive system. The current study aims to explore the miR-144 expression in colorectal cancer (CRC) cell lines and CRC stem cells (CSCs) and to explore its effect on the stemness of CSCs and the targeted regulation of Krüppel-like factor 4 (KLF4). Use qRT-PCR to detect the expression level of miR-144 in CRC cells SW480, HCT116, and H129 and the healthy colon cell NCM460. The CSCs that were used were cultured in HCT116 cells. Use western blot to explore the expressions of Nanog, SOX2, and OCT4 stemness marker protein. After it was transfected with miR-144 mimics or KLF4 plasmid, use MTT to explore the cell viability of CSCs, use flow cytometry to evaluate apoptosis, and use transwell assay to evaluate the ability of invasive of CSCs. The targeting effect of miR-144 on the KLF4 gene was verified using TargetScan prediction and the double-luciferase reporter gene test. Use qRT-PCR to evaluate the role of miR-144 mimics on KLF4 mRNA expression in CSCs. The qRT-PCR results exhibited that the miR-144 expression in CRC cells was higher than that in the healthy colon cell line. The expressions of OCT4, Nanog, and SOX2 stem cell markers were up-regulated in CSCs, and the expression of miR144 increased in CSCs. The cell viability, apoptosis, and invasion of CSCs increased after miR-144 was transfected. The TargetScan prediction and double-luciferase reporter gene assay confirmed that miR-144 was targeted by KLF4, and the expression of KLF4 mRNA in the miR-144 mimics group reduced. Moreover, the overexpression of KLF4 could partially reverse the role of miR-144 mimics on CSCs. In summary, miR-144 was highly expressed in CRC cell lines and CSCs, and the overexpression of miR-144 in CSCs significantly promoted the proliferation of CSCs, inhibited its apoptosis, and promoted its invasion ability. In addition, its preliminary mechanism, possibly through negative regulation KLF4, promotes the stemness of CSCs, and miR-144 is likely to be a potential target for eliminating CSC from CRC treatment.

MUC1-C drives stemness in progression of colitis to colorectal cancer.

Colitis is associated with the development of colorectal cancer (CRC) by largely undefined mechanisms that are critical for understanding the link between inflammation and cancer. Intestinal stem cells (ISCs) marked by leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) expression are of importance in both the inflammatory response to colitis and progression to colitis-associated colon cancer (CACC). Here, we report in human mucin 1-transgenic (MUC1-transgenic) mouse models of CACC, targeting the MUC1-C oncogenic protein suppresses the (a) Lgr5+ ISC population, (b) induction of Myc and core pluripotency stem cell factors, and (c) severity and progression of colitis to dysplasia and cancer. By extension to human colon cancer cells, we demonstrate that MUC1-C drives MYC, forms a complex with MYC on the LGR5 promoter, and activates LGR5 expression. We also show in CRC cells that MUC1-C induces cancer stem cell (CSC) markers (BMI1, ALDH1, FOXA1, LIN28B) and the OCT4, SOX2, and NANOG pluripotency factors. Consistent with conferring the CSC state, targeting MUC1-C suppresses the capacity of CRC cells to promote wound healing, invasion, self-renewal, and tumorigenicity. In analysis of human tissues, MUC1 expression associates with activation of inflammatory pathways, development of colitis, and aggressiveness of CRCs. These results collectively indicate that MUC1-C is of importance for integrating stemness and pluripotency in colitis and CRC. Of clinical relevance, the findings further indicate that MUC1-C represents a potentially previously unrecognized target that is druggable for treating progression of colitis and CRC.

Organoid modelling identifies that DACH1 functions as a tumour promoter in colorectal cancer by modulating BMP signalling.

BackgroundDachshund homologue 1 (DACH1) is highly expressed in LGR5+ intestinal stem cells and colorectal tumours. However, the roles of DACH1 in intestinal cell stemness and colorectal tumorigenesis remain largely undefined.MethodsWe used immunohistochemistry, western blotting and quantitative real-time PCR to analyse DACH1 expression in colorectal cancer (CRC) samples. CRISPR/Cas9 gene editing and lentiviral vector-mediated overexpression and shRNA-mediated knockdown of DACH1 were utilized to modulate DACH1 expression in cell lines and organoids. An intestinal organoid-based functional model was analysed, and cancer cell colony formation, sphere formation assays and murine xenotransplants were performed to reveal the role of DACH1 in CRC cell proliferation, stemness and tumorigenesis. Immunofluorescence, co-immunoprecipitation, RNA interference and microarray data analyses were conducted to demonstrate the association between DACH1 and the bone morphogenetic protein (BMP) signalling pathway.FindingsDACH1 is specifically expressed in discrete crypt base cells, and increased DACH1 expression was found in all stages of CRC. Moreover, the high expression of DACH1 independently predicted poor prognosis. In colon cancer cells, shRNA-mediated suppression of DACH1 inhibited cell growth in vitro and in vivo. By studying the intestinal organoid-based functional model, we found that depletion of DACH1 reduced the organoid formation efficiency and tumour organoid size. DACH1 overexpression stimulated both colonsphere formation and tumour organoid formation in the context of dysregulated BMP signalling. Mechanistic characterizations indicated that overexpression of DACH1 affects a subset of stem cell signature genes implicated in stem cell proliferation and maintenance through the suppression of BMP signalling via SMAD4.InterpretationTogether, our study highlights DACH1 as an integral regulator of BMP signalling during intestinal tumorigenesis, and DACH1 could be a potential prognostic marker and therapeutic target for colorectal cancer patients.

Abstract C036: Cohesins and colorectal cancer (CRC): Modulation of CRC stem cells and chemoresistance by STAG1 with race-specific implications

Abstract Despite advances in treatment and early detective measures for colorectal cancer (CRC), African-Americans (AAs) suffer disproportionately from CRC (~25% higher incidence and ~50% higher mortality) than Caucasians. Furthermore, AAs tend to receive earlier diagnoses in CRC and AA CRCs with high-grade differentiation were 3xs more likely to die within 5 yrs post-surgery as compared to whites (Alexander et al., Cancer 2005). The underlying mechanisms behind this more aggressive disease in AAs are poorly understood. Tomassati and Vogelstein postulate stem cell division correlates with risk of cancer (Science 2015). Addressing disease progression/aggressiveness, CRC stem cell markers are linked to chemoresistance; stem cell markers LGR5 and ALDH1a are established CRC stem cell markers. We have shown that the cohesin family member STAG1, a chromatin remodeler, is lost in the colonic epithelium of patients with premalignant lesions and AAs had a more profound loss (Cancer Prev Research 2016) through AA-specific STAG1 SNPs (Neoplasia 2018) and hypothesize that STAG1 loss is associated with poorer prognosis. Therefore, we wanted to investigate if STAG1 loss may lead to CRC stem cell induction as a potential mechanism of the racial disparities in CRC. RNA from rectal biopsies from 100 patients undergoing screening colonoscopies was processed for real-time PCR for CRC stem cell markers LGR5 and ALDH1a, as well as STAG1. To determine chemoresistance, STAG1 siRNA was transfected in CRC cell line HT29 and a CRISPR transfection of STAG1 SNP rs34149860 (found only in AAs) was transfected in CRC cell line RKO (possessing wildtype to SNP). Cell were treated with 5-FU and oxaliplatin and subjected to Annexin V Assay. Real-time PCR and analysis of STAG1 and CRC stem cell markers were performed for causation. AAs harboring neoplasias displayed a more robust loss of STAG1 mRNA (~50%, p<0.007) vs Caucasians with neoplasias (~25%, p=0.1). In regard to CRC stem cell markers, AAs with adenomas showed a stronger increase of LGR5 (67%, p=0.14), and ALDH1a (73%, p<0.007) vs Caucasians with neoplasias (LGR5 increased 59%, p=0.2; ALDH1a increased ~47%, p<0.05). HT29 cells transfected with STAG1 siRNA showed 30% less apoptotic response to 5-FU vs scramble vector and a marked 74% less response with oxaliplatin. CRIPSR SNP transfection in RKO showed similar effects, with a 2-fold less apoptotic response to 5-FU and >90% less response to oxaliplatin. PCR showed RKO STAG1-SNP transfected cells displayed a loss of STAG1(~40%, p<0.05) and an upregulation of LGR5 (~50%, p<0.05) and ALDH1a (~30%, p<0.05). This shows, for the first time, that STAG1 loss is implicated in colon carcinogenesis through potentiation of cancer stem cells through early carcinogenesis/initiation as well as disease progression and aggressiveness as shown through chemoresistance. Our work provides a potential mechanism in CRC, thus providing a biomarker for cancer screening and therapeutics that could mitigate the racial disparity of CRC in AAs. Citation Format: Mart Dela Cruz, Caroline Zaworski, Somenath Datta, Sanjib Chowdhury, Hemant K. Roy. Cohesins and colorectal cancer (CRC): Modulation of CRC stem cells and chemoresistance by STAG1 with race-specific implications [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C036.

MIR600HG suppresses metastasis and enhances oxaliplatin chemosensitivity by targeting ALDH1A3 in colorectal cancer.

Background: Metastasis and chemoresistance indicate a poor prognosis in colorectal cancer (CRC) patients. However, the mechanisms that lead to the development of chemoresistance and metastasis in CRC remain unclear.Materials and methods: We combined clinical and experimental studies to determine the role of MIR600HG in CRC metastasis and chemoresistance. The statistical analysis was performed using GraphPad Prism software, version 8.0.Results: We detected down-regulated expression of long non-coding RNA (lncRNA) MIR600HG in CRC specimens and cell lines compared with normal controls, and the expression level of MIR600HG was inversely correlated with the overall survival of CRC patients. The inhibition of MIR600HG stimulated CRC cell metastasis and chemoresistance. In addition, our data showed that the inhibition of MIR600HG stimulated CRC stemness, while the overexpression of MIR600HG suppressed stemness. Importantly, our animal experiments showed that MIR600HG inhibited tumour formation and that the combination of MIR600HG inhibition and oxaliplatin (Oxa) treatment significantly inhibited tumour growth compared with that with either intervention alone. Furthermore, we demonstrated that MIR600HG exerts its anticancer role by targeting ALDH1A3 in CRC.Conclusions: Our data suggest that MIR600HG functions as a tumour suppressor and that the overexpression of MIR600HG inhibits tumour invasion and enhances chemosensitivity, providing a new strategy for CRC treatment.

Silencing DVL3 defeats MTX resistance and attenuates stemness via Notch Signaling Pathway in colorectal cancer

Chemoresistance and recurrence of colorectal cancer are mainly caused by the existence of cancer stem-like cells. Dishevelled-3 (DVL3) is a common member of both Wnt/β-catenin pathway and the Notch signaling pathway, which were involved in cancer progression, chemoresistance and even maintenance of stem cell-like properties. However, the underlying biological function of DVL3 still remains unclear. In this study, we proposed DVL3 was simultaneously involved in Methotrexate (MTX) resistance and Colorectal cancer (CRC) stemness by bioinformatic analysis. We also demonstrated DVL3 knockdown sensitized CRC cells to MTX and inhibited their stem cell-like properties by functional experiments. As for the mechanism, DVL3 silencing attenuated the activated Notch signaling by down-regulating Notch intracellular domain (NICD) as well as its downstream targets. Additionally, we demonstrated that CRC cancer tissues had greater DVL3 expression than adjacent non-cancer tissues and patients’ overall survival was closely associated with DVL3 according to the data in our clinical center. Accordingly, our data suggest that DVL3 is a key regulator in CRC stemness and chemoresistance and targeting DVL3 could be a potential strategy for CRC therapy.

MeCP2 Promotes Colorectal Cancer Metastasis by Modulating ZEB1 Transcription.

Background: Recurrence and distant organ metastasis is a major cause of death in colorectal cancer (CRC); however, the underlying molecular mechanisms regulating this phenomenon are poorly understood. MeCP2 is a key epigenetic regulator and is amplified in many types of cancer. Its role in CRC and the molecular mechanisms underlying its action remain unknown. Methods: We used western blot and immunohistochemistry to detect MeCP2 expression in CRC tissues, and then investigated its biological functions in vitro and in vivo. Chromatin immunoprecipitation, co-immunoprecipitation, and electrophoretic mobility shift assays were used to detect the associations among MeCP2 (Methyl-CpG binding protein 2), SPI1 (Spi-1 Proto-Oncogene), and ZEB1 (Zinc Finger E-Box Binding Homeobox 1). Results: Using the Cancer Genome Atlas and Oncomine databases, we found MeCP2 expression was upregulated in CRC tissues and this upregulation was related to poor prognosis. Meanwhile, MeCP2 depletion (KO/KD) in CRC cells significantly inhibited stem cell frequency, and invasion and migration ability in vitro, and suppressed CRC metastasis in vivo. Mechanistically, we show MeCP2 binds to the transcription factor SPI1, and aids its recruitment to the ZEB1 promoter. SPI1 then facilitates ZEB1 expression at the transcription level. In turn, ZEB1 induces the expression of MMP14, CD133, and SOX2, thereby maintaining CRC stemness and metastasis. Conclusions: MeCP2 is a novel regulator of CRC metastasis. MeCP2 suppression may be a promising therapeutic strategy in CRC.

Bufalin reverses multidrug resistance by regulating stemness through the CD133/nuclear factor-κB/MDR1 pathway in colorectal cancer.

Recent studies have shown that MDR could be induced by the high stemness of cancer cells. In a previous study, we found bufalin could reverse MDR and inhibit cancer cell stemness in colorectal cancer, but the relationship between them was unclear. Here we identified overexpressing CD133 increases levels of Akt/nuclear factor‐κB signaling mediators and MDR1, while increasing cell chemoresistance. Furthermore, bufalin reverses colorectal cancer MDR by regulating cancer cell stemness through the CD133/nuclear factor‐κB/MDR1 pathway in vitro and in vivo. Taken together, our results suggest that bufalin could be developed as a novel 2‐pronged drug that targets CD133 and MDR1 to eradicate MDR cells and could ultimately be combined with conventional chemotherapeutic agents to improve treatment outcomes for patients with colorectal cancer.

Small molecule-induced simultaneous destabilization of \u03b2-catenin and RAS is an effective molecular strategy to suppress stemness of colorectal cancer cells

BackgroundCancer stem cells (CSCs), the major driver of tumorigenesis, is a sub-population of tumor cells responsible for poor clinical outcomes. However, molecular mechanism to identify targets for controlling CSCs is poorly understood.MethodsGene Set Enrichment Analyses (GSEA) of Wnt/β-catenin and RAS signaling pathways in stem-like subtype of colorectal cancer (CRC) patients were performed using two gene expression data set. The therapeutic effects of destabilization of β-catenin and RAS were tested by treatment of small molecule KYA1797K using CRC patient derived cells.ResultsTreatment with KYA1797K, a small molecule that destabilizes both β-catenin and RAS via Axin binding, effectively suppresses the stemness of CSCs as shown in CRC spheroids and small intestinal tumors of ApcMin/+/K-RasG12DLA2 mice. Moreover, KYA1797K also suppresses the stemness of cells in CRC patient avatar model systems, such as patient-derived tumor organoids (PDTOs) and patient-derived tumor xenograft (PDTX).ConclusionOur results suggest that destabilization of both β-catenin and RAS is a potential therapeutic strategy for controlling stemness of CRC cells.EL4qu77E_Vg6o-DHLyPXBuVideo abstract

LncRNA-ATB promotes stemness maintenance in colorectal cancer by regulating transcriptional activity of the β-catenin pathway.

Long non-coding RNA activated by transforming growth factor-β (ATB) was recently reported to be involved in a wide range of physiological and pathological processes. However, the role of ATB in colorectal cancer (CRC) stemness remains unclear. In the present study, the functional role of ATB in maintaining stemness of CRC was determined using colony formation and sphere formation assays, and xenograft models. Reverse transcription-quantitative PCR, western blotting and immunohistochemistry were performed to investigate the mechanisms underlying the effects of ATB. Knockdown of ATB impaired colony formation and sphere formation in CRC cells, accompanied by an inhibition of colon tumor growth. Further results suggested that ATB regulated the transcriptional activity of the β-catenin pathway by inhibiting β-catenin expression. In addition, the results confirmed the role of β-catenin in ATB-mediated regulation of stemness in CRC. Collectively, the results indicated that ATB is a promising therapeutic target for CRC.

Overexpression of miR-17 is correlated with liver metastasis in colorectal cancer.

Background:Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in men and women. The presence of systemic disease, with metastatic spread to distant sites such as the liver, considerably reduces the survival rate in CRC. Cancer stem cells contribute to the metastatic potential of CRC. However, the mechanism underlying metastasis in CRC remains unclear. Thus, this study aimed to examine the expression of microRNAs (miRNAs) in CRC stem cells in cases of liver metastases and assess their correlation with clinicopathological features.Methods:miRNAs showing high expression in liver metastases and primary lesions were selected through data mining of gene expression omnibus datasets, and miRNAs characteristic of stem cells were selected through COREMINE medical text mining. Subsequently, paired formalin-fixed paraffin-embedded tissue samples of primary CRC and liver metastasis from 30 patients were examined for the expression of miRNAs common to these lists (hsa-miR-20a, hsa-miR-26b, hsa-miR-146a, hsa-miR-17, hsa-miR-451, hsa-miR-23a, and hsa-miR-29a) using quantitative real-time polymerase chain reaction. Further, miRNA expression was compared between liver metastases and the primary tumor in each patient and the factors associated with differential expression were analyzed.Results:hsa-miR-17 was significantly upregulated in liver metastases (P < .05), but no significant difference in the expression of hsa-miR-26b, hsa-miR-146a, hsa-miR-451, hsa-miR-23a, and hsa-miR-29a was observed between primary tumors and liver metastases. The higher expression of hsa-miR-17 in liver metastases was associated with the administration of neoadjuvant chemotherapy and tumor differentiation (P < .05) but was not associated with age, sex, tumor location, or lymphatic metastasis.Conclusions:High expression of miR-17 may contribute to liver metastasis in CRC. Therefore, an in-depth understanding of its downstream pathways could help in elucidating the mechanisms underlying liver metastases in CRC. However, additional studies are warranted to validate these findings.

Exosomes from CD133+ cells carrying circ-ABCC1 mediate cell stemness and metastasis in colorectal cancer.

Colorectal cancer (CRC), a fatal tumor, has been diagnosed as one of the most prevalent types of cancers globally, inducing multiple cancer-linked deaths. Mounting evidence has revealed that circular RNA (circRNA) elicits a regulatory impact on the initiation and development of cancers. Emerged as a new circRNA, hsa_circ_0000677 (circ-ABCC1) has not been studied in cancer progression. This study is the first attempt to explore the regulatory role of circ-ABCC1 in CRC. In this study, data from sphere-forming, transwell, and Western blot analyses revealed that cell stemness, sphere formation, and metastasis were notably enhanced in CD133+ cells isolated from CRC cells. In addition, exosomes from CD133+ cells could promote cell stemness, sphere formation, and metastasis. Moreover, circ-ABCC1 was verified to be characterized with a loop structure through quantitative reverse-transcription polymerase chain reaction analysis. Functional assays testified that the upregulation of circ-ABCC1 contributed to cell stemness, sphere formation, and metastasis in CD133- /Caco2 or CD133- /HCT15 cells. Furthermore, the interaction between circ-ABCC1 and β-catenin was analyzed via RNA immunoprecipitation and RNA pull-down and finally, circ-ABCC1 was confirmed to facilitate CRC progression by activating the Wnt/β-catenin pathway. To sum up, exosomes from CD133+ cells carrying circ-ABCC1 can mediate cell stemness and metastasis in CRC, unveiling that circ-ABCC1 serves as a novel candidate target for CRC treatment.

TCF4 promotes colorectal cancer drug resistance and stemness via regulating ZEB1/ZEB2 expression.

The present study aims to investigate the roles of TCF4 and its underlying mechanism in colorectal cancer (CRC). Doxorubicin-resistant DLD-1 (DLD1 DR), TCF4 overexpression, and TCF4 knockdown cell lines were constructed. A flow cytometer was used to analyze frequencies of CD133+ cell in the DLD1 and DLD1 DR cells. Quantitative real-time PCR (qPCR) was used to determine the expressions of cancer stem cell (CSC) makers. Stemness of CRC cells were determined using tumorsphere formation assay. The correlation between TCF4 and ZEB1/ZEB2 were determined using public data from The Cancer Genome Atlas (TCGA) datasets. ZEB1/ZEB2 overexpression cell lines were constructed and cell viabilities were then determined using MTT and colony formation assays. TCF4 overexpression promoted proliferation of CRC cell lines and relative expressions of TCF4 were significantly increased in the DLD1 DR cells. TCF4 overexpression promoted CRC cell doxorubicin resistance, whereas TCF4 knockdown significantly decreased doxorubicin resistance. Additionally, TCF4 overexpression also significantly increased frequencies of CSC cells, expressions of CSC markers, and CRC ability to form tumorsphere. Furthermore, TCF4 promoted ZEB1 and ZEB2 expression, leading to CRC proliferation and doxorubicin resistance. TCF4 promoted CRC doxorubicin resistance and stemness by regulating expressions of ZEB1 and ZEB2.

Inhibiting EMT, stemness and cell cycle involved in baicalin-induced growth inhibition and apoptosis in colorectal cancer cells.

Although baicalin, a flavonoid derived from Scutellaria baicalensis Georgi, has been reported to have anti-tumor activity in various cancers, the molecular mechanism remains imperfect. Here, we show that baicalin inhibits cell growth, migration and invasion and induces cell apoptosis by inhibiting cell cycle, viability, the epithelial-mesenchymal transition (EMT) and cellular stemness in colorectal cancer (CRC) cells. In detail, baicalin treatment in CRC cells induces cell cycle arrest in G1 phase and promotes p53-independent cell apoptosis, inhibits both endogenous and exogenous TGFβ1-induced EMT of colorectal cancer cells by inhibiting TGFβ/Smad pathway. Cell sphere-formation experiments show that baicalin has a strong inhibitory efficacy on the stemness of CRC cells by decreasing the marker proteins of cancer stem cell (CSC) and inhibits the formation of CSC-like cell spheres in CRC cells. In vivo experiments also identify that baicalin has an anti-tumor effect by down-regulating the levels of marker proteins of cell cycle, EMT and stemness in the orthotopic transplantation tumors of CRC cells in BALB/c nude mice. Collectively, our in vitro and in vivo results indicate that multiple inhibition of cell cycle, EMT and stemness is the real molecular mechanism of baicalin in effectively inducing cell growth inhibition and apoptosis in CRC cells.