Inhibition of LEF1-Mediated DCLK1 by Niclosamide Attenuates Colorectal Cancer Stemness

N6-methyladenosine methylation analysis of long noncoding RNAs and mRNAs in 5-FU-resistant colon cancer cells

N6 methyladenosine (m6A), methylation at the sixth N atom of adenosine, is the most common and abundant modification in mammalian mRNAs and non-coding RNAs. Increasing evidence shows that the alteration of m6A modification level could regulate tumour proliferation, metastasis, self-renewal, and immune infiltration by regulating the related expression of tumour genes. However, the role of m6A modification in colorectal cancer (CRC) drug resistance is unclear. Here, MeRIP-seq and RNA-seq techniques were utilized to obtain mRNA, lncRNA expression, and their methylation profiles in 5-Fluorouracil (5-FU)-resistant colon cancer HCT-15 cells and control cells. In addition, we performed detailed bioinformatics analysis as well as in vitro experiments of lncRNA to explore the function of lncRNA with differential m6A in CRC progression and drug resistance. In this study, we obtained the m6A methylomic landscape of CRC cells and resistance group cells by MeRIP-seq and RNA-seq. We identified 3698 differential m6A peaks, of which 2224 were hypermethylated, and 1474 were hypomethylated. Among the lncRNAs, 60 were hypermethylated, and 38 were hypomethylated. GO and KEGG analysis annotations showed significant enrichment of endocytosis and MAPK signalling pathways. Moreover, knockdown of lncRNA ADIRF-AS1 and AL139035.1 promoted CRC proliferation and invasive metastasis in vitro. lncRNA- mRNA network showed that ADIRF-AS1 and AL139035.1 May play a key role in regulating drug resistance formation. We provide the first m6A methylation profile in 5-FU resistance CRC cells and analyse the functions of differential m6A-modified mRNAs and lncRNAs. Our results indicated that differential m6A RNAs were significantly associated with MAPK signalling and endocytosis after induction of 5-FU resistance. Knockdown of LncRNA ADIRF-AS1 and AL139035.1 promotes CRC progression and might be critical in regulating drug resistance formation.

Identification of master regulator genes controlling pathogenic CD4+ T cell fate in inflammatory bowel disease through transcriptional network analysis

Inflammatory bowel diseases (IBD) are a group of chronic inflammatory conditions of the gastrointestinal tract associated with multiple pathogenic factors, including dysregulation of the immune response. Effector CD4+ T cells and regulatory CD4+ T cells (Treg) are central players in maintaining the balance between tolerance and inflammation. Interestingly, genetic modifications in these cells have been implicated in regulating the commitment of specific phenotypes and immune functions. However, the transcriptional program controlling the pathogenic behavior of T helper cells in IBD progression is still unknown. In this study, we aimed to find master transcription regulators controlling the pathogenic behavior of effector CD4+ T cells upon gut inflammation. To achieve this goal, we used an animal model of IBD induced by the transfer of naïve CD4+ T cells into recombination-activating gene 1 (Rag1) deficient mice, which are devoid of lymphocytes. As a control, a group of Rag1-/- mice received the transfer of the whole CD4+ T cells population, which includes both effector T cells and Treg. When gut inflammation progressed, we isolated CD4+ T cells from the colonic lamina propria and spleen tissue, and performed bulk RNA-seq. We identified differentially up- and down-regulated genes by comparing samples from both experimental groups. We found 532 differentially expressed genes (DEGs) in the colon and 30 DEGs in the spleen, mostly related to Th1 response, leukocyte migration, and response to cytokines in lamina propria T-cells. We integrated these data into Gene Regulatory Networks to identify Master Regulators, identifying four up-regulated master gene regulators (Lef1, Dnmt1, Mybl2, and Jup) and only one down-regulated master regulator (Foxo3). The altered expression of master regulators observed in the transcriptomic analysis was confirmed by qRT-PCR analysis and found an up-regulation of Lef1 and Mybl2, but without differences on Dnmt1, Jup, and Foxo3. These two master regulators have been involved in T cells function and cell cycle progression, respectively. We identified two master regulator genes associated with the pathogenic behavior of effector CD4+ T cells in an animal model of IBD. These findings provide two new potential molecular targets for treating IBD.

CK2α-mediated phosphorylation of GRP94 facilitates the metastatic cascade in triple-negative breast cancer

Distant metastasis is a significant hallmark affecting to the high death rate of patients with triple-negative breast cancer (TNBC). Thus, it is crucial to identify and develop new therapeutic strategies to hinder cancer metastasis. While emerging studies have hinted a pivotal role of glucose-regulated protein 94 (GRP94) in tumorigenesis, the exact biological functions and molecular mechanisms of GRP94 in modulating cancer metastasis remain to be elucidated. Our study demonstrated an increased expression of GRP94 in TNBC correlated with metastatic progression and unfavorable prognosis in patients. Functionally, we identified that GRP94 depletion significantly diminished TNBC tumorigenesis and subsequent lung metastasis. In contrast, GRP94 overexpression exacerbated the invasiveness, migration, and lung metastasis of non-TNBC cells. Mechanistically, we found that casein kinase 2 alpha (CK2α) active in advanced breast cancer phosphorylated GRP94 at a conserved serine 306 (S306) residue. This phosphorylation increased the stability of GRP94 and enhanced its interaction with LRP6, leading to activation of canonical Wnt signaling. From a therapeutic standpoint, we found that benzamidine, a novel CK2α inhibitor, effectively suppressed GRP94 phosphorylation, LRP6 stabilization, and metastasis of TNBC. Our results point to the critical role of CK2α-mediated GRP94 phosphorylation in TNBC metastasis through activation of Wnt signaling, highlighting GRP94 as a therapeutic target to impede TNBC metastasis.

Metabolic vulnerability of cancer stem cells and their niche

Cancer stem cells (CSC) are the leading cause of the failure of anti-tumor treatments. These aggressive cancer cells are preserved and sustained by adjacent cells forming a specialized microenvironment, termed niche, among which tumor-associated macrophages (TAMs) are critical players. The cycle of tricarboxylic acids, fatty acid oxidation path, and electron transport chain have been proven to play central roles in the development and maintenance of CSCs and TAMs. By improving their oxidative metabolism, cancer cells are able to extract more energy from nutrients, which allows them to survive in nutritionally defective environments. Because mitochondria are crucial bioenergetic hubs and sites of these metabolic pathways, major hopes are posed for drugs targeting mitochondria. A wide range of medications targeting mitochondria, electron transport chain complexes, or oxidative enzymes are currently investigated in phase 1 and phase 2 clinical trials against hard-to-treat tumors. This review article aims to highlight recent literature on the metabolic adaptations of CSCs and their supporting macrophages. A focus is provided on the resistance and dormancy behaviors that give CSCs a selection advantage and quiescence capacity in particularly hostile microenvironments and the role of TAMs in supporting these attitudes. The article also describes medicaments that have demonstrated a robust ability to disrupt core oxidative metabolism in preclinical cancer studies and are currently being tested in clinical trials.

Repurposing diacerein to suppress colorectal cancer growth by inhibiting the DCLK1/STAT3 signaling pathway

Double cortin-like kinase 1 (DCLK1) exhibits high expression levels across various cancers, notably in human colorectal cancer (CRC). Diacerein, a clinically approved interleukin (IL)-1β inhibitor for osteoarthritis treatment, was evaluated for its impact on CRC proliferation and migration, alongside its underlying mechanisms, through both in vitro and in vivo analyses. The study employed MTT assay, colony formation, wound healing, transwell assays, flow cytometry, and Hoechst 33342 staining to assess cell proliferation, migration, and apoptosis. Additionally, proteome microarray assay and western blotting analyses were conducted to elucidate diacerein's specific mechanism of action. Our findings indicate that diacerein significantly inhibits DCLK1-dependent CRC growth in vitro and in vivo. Through high-throughput proteomics microarray and molecular docking studies, we identified that diacerein directly interacts with DCLK1. Mechanistically, the suppression of p-STAT3 expression following DCLK1 inhibition by diacerein or specific DCLK1 siRNA was observed. Furthermore, diacerein effectively disrupted the DCLK1/STAT3 signaling pathway and its downstream targets, including MCL-1, VEGF, and survivin, thereby inhibiting CRC progression in a mouse model, thereby inhibiting CRC progression in a mouse model.

Chondroitin Sulfate Proteoglycan 4 Provides New Treatment Approach to Preventing Peritoneal Dissemination in Ovarian Cancer

Most epithelial ovarian cancer (EOC) patients are diagnosed with peritoneal dissemination. Cellular interactions are an important aspect of EOC cells when they detach from the primary site of the ovary. However, the mechanism remains underexplored. Our study aimed to reveal the role of chondroitin sulfate proteoglycan 4 (CSPG4) in EOC with a major focus on cell-cell interactions. We examined the expression of CSPG4 in clinical samples and cell lines of EOC. The proliferation, migration, and invasion abilities of the CSPG4 knockdown cells were assessed. We also assessed the role of CSPG4 in spheroid formation and peritoneal metastasis in an in vivo model using sh-CSPG4 EOC cell lines. Of the clinical samples, 23 (44.2%) samples expressed CSPG4. CSPG4 was associated with a worse prognosis in patients with advanced EOC. Among the EOC cell lines, aggressive cell lines, including ES2, expressed CSPG4. When CSPG4 was knocked down using siRNA or shRNA, the cell proliferation, migration, and invasion abilities were significantly decreased compared to the control cells. Proteomic analyses showed changes in the expression of proteins related to the cell movement pathways. Spheroid formation was significantly inhibited when CSPG4 was inhibited. The number of nodules and the tumor burden of the omentum were significantly decreased in the sh-CSPG4 mouse models. In the peritoneal wash fluid from mice injected with sh-CSPG4 EOC cells, significantly fewer spheroids were present. Reduced CSPG4 expression was observed in lymphoid enhancer-binding factor 1-inhibited cells. CSPG4 is associated with aggressive features of EOC and poor prognosis. CSPG4 could be a new treatment target for blocking peritoneal metastasis by inhibiting spheroid formation.

Epigenetic Landscape and Therapeutic Implication of Gene Isoforms of Doublecortin-Like Kinase 1 for Cancer Stem Cells

While significant strides have been made in understanding cancer biology, the enhancement in patient survival is limited, underscoring the urgency for innovative strategies. Epigenetic modifications characterized by hereditary shifts in gene expression without changes to the DNA sequence play a critical role in producing alternative gene isoforms. When these processes go awry, they influence cancer onset, growth, spread, and cancer stemness. In this review, we delve into the epigenetic and isoform nuances of the protein kinase, doublecortin-like kinase 1 (DCLK1). Recognized as a hallmark of tumor stemness, DCLK1 plays a pivotal role in tumorigenesis, and DCLK1 isoforms, shaped by alternative promoter usage and splicing, can reveal potential therapeutic touchpoints. Our discussion centers on recent findings pertaining to the specific functions of DCLK1 isoforms and the prevailing understanding of its epigenetic regulation via its two distinct promoters. It is noteworthy that all DCLK1 isoforms retain their kinase domain, suggesting that their unique functionalities arise from non-kinase mechanisms. Consequently, our research has pivoted to drugs that specifically influence the epigenetic generation of these DCLK1 isoforms. We posit that a combined therapeutic approach, harnessing both the epigenetic regulators of specific DCLK1 isoforms and DCLK1-targeted drugs, may prove more effective than therapies that solely target DCLK1.

The DUBA-SLC7A11-c-Myc axis is critical for stemness and ferroptosis

Ferroptosis is characterized by the accumulation of lipid peroxidation as a unique iron-dependent cell death. However, the interplay between stemness and ferroptosis remains unknown. Here, we demonstrate that undifferentiated cells are more sensitive to ferroptosis than differentiated cells, and cystine transporter SLC7A11 protein is highly up-regulated by deubiquitinase DUBA in differentiated cells. Additionally, DUBA promotes stemness by deubiquitinating SLC7A11. Moreover, SLC7A11 drastically increases the expression of c-Myc through cysteine, the combination of sorafenib and c-Myc inhibitor EN4 has a synergetic effect on cancer therapy. Together, our results reveal that enhanced stemness increases the susceptibility to ferroptosis, and the DUBA-SLC7A11-c-Myc axis is pivotal for differentiated cancer stem cells (CSCs) resistant to ferroptosis, providing a promised targets to eradicate CSCs through ferroptosis.

Targeting DCLK1 attenuates tumor stemness and evokes antitumor immunity in triple-negative breast cancer by inhibiting IL-6/STAT3 signaling

Triple-negative breast cancer (TNBC) exhibits the poorest outcomes among breast cancer subtypes due to the high heterogeneity and a lasting scarcity of effectual treatments. Targeted therapies based on molecular subtypes of TNBC are critical step toward tailoring treatments to improve clinical outcomes. Gastrointestinal cancer stem cell (CSC) marker DCLK1 was reported to be highly expressed in stem cell-rich subtype of TNBC. Here, we firstly explored the impacts of DCLK1 on tumor cells as well as their immune microenvironment in TNBC and potential therapeutic strategies for TNBC patients with high DCLK1 expression. Our results disclosed that DCLK1 overexpression promoted, while knockout of DCLK1 suppressed the CSC-like traits of TNBC cells and resistance to chemotherapeutics. Besides, DCLK1 supported immune escape by inhibiting intratumoral cytotoxic T cell infiltration in TNBC and hence limited immune checkpoint inhibitors efficacy. Mechanistically, bioinformatics analysis revealed that IL-6/STAT3 signaling was significantly enriched in high DCLK1-expressing patients, and our results further revealed that DCLK1 enhanced IL-6 expression and STAT3 activation in TNBC cells, which finally gave rise to upregulated CSC traits and suppressed CD8+ T-cell activity. Inhibiting IL-6/STAT3 pathway by IL-6R antagonist, Tocilizumab or STAT3 inhibitor, S31-201 could abolish DCLK1-promoted malignant phenotypes of TNBC cells. Finally, DCLK1 was identified to be specifically and highly expressed in the mesenchymal-like subtype of TNBC and targeting DCLK1 could improve chemotherapy efficacy and activate antitumor immunity. Overall, our study revealed the potential clinical benefits of targeting DCLK1 in TNBC treatment.

β-Sitosterol blocks the LEF-1-mediated Wnt/β-catenin pathway to inhibit proliferation of human colon cancer cells

OBJECTIVES

This study aimed to investigate the LEF-1-mediated Wnt/β-catenin pathway for its biological functions and prognostic value in colon cancer (CC). Furthermore, the potential molecular mechanism of β-sitosterol in CC was investigated in vitro.

METHODS

Clinical information and gene expression profiles from CC patients were obtained based on Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. In addition, we applied R software "Limma" package for the differential analysis of LEF-1 between cancer and para-carcinoma tissue samples. Kaplan-Meier (KM) survival analysis was adopted for analyzing whether LEF-1 was of prognostic significance. Moreover, gene set enrichment analysis (GSEA) was adopted for pathway enrichment analysis and visualization. In addition, CCK8, plate cloning, scratch and high-content screening (HCS) imaging assays were performed to examine the therapeutic efficacy of β-sitosterol in human CC HCT116 cells. siRNA technology was employed to knock down LEF1 expression in HCT116 cells. qRT-PCR and Western-blot (WB) analysis were carried out to analyze the HCT-116 mRNA and protein expression levels, respectively.

RESULTS

LEF-1 was up-regulated within CC and acted as an oncogenic gene. LEF-1 up-regulation predicted the dismal prognostic outcome and activated the Wnt/β-catenin pathway. β-sitosterol effectively suppressed HCT116 cells proliferation and invasion. For the mechanism underlying β-sitosterol, β-sitosterol was found to significantly down-regulate LEF-1 gene and protein expression and disrupt Wnt/β-catenin pathway transmission in HCT116 cells. After suppressing LEF-1 expression, its downstream targets including C-myc, Survivin and CCND1 were also down-regulated.

CONCLUSION

According to our results, LEF-1 down-regulation can effectively block Wnt/β-catenin pathway, inhibit CC cell growth and migration. Collectively, β-sitosterol can be used to treat CC, which can provide anti-tumor activity by targeting LEF-1.

Niclosamide inhibits epithelial-mesenchymal transition with apoptosis induction in BRAF/ NRAS mutated metastatic melanoma cells

Malignant melanoma is considered a deadly aggressive form of skin cancer that frequently metastasizes to various distal organs, which harbors mutations of the BRAF or NRAS which occur in 30 to 50% of melanoma patients. The growth factors secreted by melanoma cells contribute to tumor angiogenesis with the acquisition of metastatic potential by epithelial-mesenchymal transition (EMT) and drive melanoma growth toward a more aggressive form. Niclosamide (NCL) is an FDA-approved anthelmintic drug and is reported to have strong anti-cancer properties against various solid and liquid tumors. Its role in BRAF or NRAS mutated cells is unknown. In this context, we uncovered the role of NCL in impeding malignant metastatic melanoma in vitro in SK-MEL-2 and SK-MEL-28 cell lines. We found that NCL induces significant ROS generation and apoptosis through a series of molecular mechanisms, such as depolarization of mitochondrial membrane potential, arresting the cell cycle at the sub G1 phase with a significant increase in the DNA cleavage via topoisomerase II in both cell lines. We also found that NCL potently inhibited metastasis, which was examined by scratch wound assay, Additionally, we found that NCL inhibits the most important markers involved in the EMT signaling cascade that are stimulated by TGF-β such as N-cadherin, Snail, Slug, Vimentin, α-SMA and p-Smad 2/3. This work provides useful insights into the mechanism of NCL in BRAF/NRAF mutant melanoma cells via inhibition of molecular signaling events involved in EMT signaling, and apoptosis induction.

A Dual-Responsive STAT3 Inhibitor Nanoprodrug Combined with Oncolytic Virus Elicits Synergistic Antitumor Immune Responses by Igniting Pyroptosis

Immune checkpoint blockade (ICB) therapy shows excellent efficacy against malignancies; however, insufficient tumor immunogenicity and the immunosuppressive tumor microenvironment (TME) are considered as the two major stumbling blocks to a broad ICB response. Here, a combinational therapeutic strategy is reported, wherein TME-reactive oxygen species/pH dual-responsive signal transducers and activators of transcription 3 inhibitor nanoprodrugs MPNPs are combined with oncolytic herpes simplex virus 1 virotherapy to synergistically ignite pyroptosis for enhancing immunotherapy. MPNPs exhibit a certain level of tumor accumulation, reduce tumor cell stemness, and enhance antitumor immune responses. Furthermore, the simultaneous application of oncolytic viruses (OVs) confers MPNPs with higher tumor penetration capacity and remarkable gasdermin-E-mediated pyroptosis, thereby reshaping the TME and transforming "cold" tumors into "hot" ones. This "fire of immunity" strategy successfully activates robust T-cell-dependent antitumor responses, potentiating ICB effects against local recurrence and pulmonary metastasis in preclinical "cold" murine triple-negative breast cancer and syngeneic oral cancer models. Collectively, this work may pave a new way and offer an unprecedented opportunity for the combination of OVs with nanomedicine for cancer immunotherapy.

SOX2-high cancer cells exhibit an aggressive phenotype, with increases in stemness, proliferation and invasion, as well as higher metabolic activity and ATP production

Cancer stem cells (CSCs) are responsible for cancer recurrence, treatment failure and metastatic dissemination. As such, the elimination of CSCs represents one of the most important approaches for the future of cancer treatment. Among other properties, CSCs show the activation of particular cell signalling pathways and the over-expression of certain transcription factors, such as SOX2. Herein, we describe a new model system to isolate stem-like cancer cells, based on the functional transcriptional activity of SOX2. Briefly, we employed a SOX2-enhancer-GFP-reporter system to isolate cancer cells with high SOX2 transcriptional activity by FACS sorting. The over-expression of SOX2 in this sub-population was validated by Western blot analysis and flow cytometry. SOX2-high cancer cells showed CSCs features, such as greater mammosphere forming ability, validating that this sub-population was enriched in CSCs. To further explore the model, we analysed other stemness characteristics in MCF7 and MDA-MB-231 breast cancer cell lines, corroborating that SOX2-high cells were more metabolically active, proliferative, migratory, invasive, and drug-resistant. SOX2-high MDA-MB-231 cells also showed a loss of E-cadherin expression, and increased Vimentin expression, consistent with an epithelial-mesenchymal transition (EMT). Therefore, endogenous SOX2 transcriptional activity and protein levels are mechanistically linked to aggressive phenotypic behaviours and energy production in CSCs.

Niclosamide as a Promising Therapeutic Player in Human Cancer and Other Diseases

Niclosamide is an FDA-approved anthelmintic drug for the treatment of parasitic infections. However, over the past few years, increasing evidence has shown that niclosamide could treat diseases beyond parasitic diseases, which include metabolic diseases, immune system diseases, bacterial and viral infections, asthma, arterial constriction, myopia, and cancer. Therefore, we systematically reviewed the pharmacological activities and therapeutic prospects of niclosamide in human disease and cancer and summarized the related molecular mechanisms and signaling pathways, indicating that niclosamide is a promising therapeutic player in various human diseases, including cancer.

Emerging roles for IL-25 and IL-33 in colorectal cancer tumorigenesis

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide, and is largely refractory to current immunotherapeutic interventions. The lack of efficacy of existing cancer immunotherapies in CRC reflects the complex nature of the unique intestinal immune environment, which serves to maintain barrier integrity against pathogens and harmful environmental stimuli while sustaining host-microbe symbiosis during homeostasis. With their expression by barrier epithelial cells, the cytokines interleukin-25 (IL-25) and IL-33 play key roles in intestinal immune responses, and have been associated with inappropriate allergic reactions, autoimmune diseases and cancer pathology. Studies in the past decade have begun to uncover the important roles of IL-25 and IL-33 in shaping the CRC tumour immune microenvironment, where they may promote or inhibit tumorigenesis depending on the specific CRC subtype. Notably, both IL-25 and IL-33 have been shown to act on group 2 innate lymphoid cells (ILC2s), but can also stimulate an array of other innate and adaptive immune cell types. Though sometimes their functions can overlap they can also produce distinct phenotypes dependent on the differential distribution of their receptor expression. Furthermore, both IL-25 and IL-33 modulate pathways previously known to contribute to CRC tumorigenesis, including angiogenesis, tumour stemness, invasion and metastasis. Here, we review our current understanding of IL-25 and IL-33 in CRC tumorigenesis, with specific focus on dissecting their individual function in the context of distinct subtypes of CRC, and the potential prospects for targeting these pathways in CRC immunotherapy.

Pleiotropic effects of DCLK1 in cancer and cancer stem cells

Doublecortin-like kinase 1 (DCLK1), a protein molecule, has been identified as a tumor stem cell marker in the cancer cells of gastrointestinal, pancreas, and human colon. DCLK1 expression in cancers, such as breast carcinoma, lung carcinoma, hepatic cell carcinoma, tuft cells, and human cholangiocarcinoma, has shown a way to target the DCLK1 gene and downregulate its expression. Several studies have discussed the inhibition of tumor cell proliferation along with neoplastic cell arrest when the DCLK1 gene, which is expressed in both cancer and normal cells, was targeted successfully. In addition, previous studies have shown that DCLK1 plays a vital role in various cancer metastases. The correlation of DCLK1 with numerous stem cell receptors, signaling pathways, and genes suggests its direct or an indirect role in promoting tumorigenesis. Moreover, the impact of DCLK1 was found to be related to the functioning of an oncogene. The downregulation of DCLK1 expression by using targeted strategies, such as embracing the use of siRNA, miRNA, CRISPR/Cas9 technology, nanomolecules, specific monoclonal antibodies, and silencing the pathways regulated by DCLK1, has shown promising results in both in vitro and in vivo studies on gastrointestinal (GI) cancers. In this review, we will discuss about the present understanding of DCLK1 and its role in the progression of GI cancer and metastasis.

Oncogenic functions and clinical significances of DCLK1 isoforms in colorectal cancer: a systematic review and meta-analysis

Background

The oncogenic role of doublecortin-like kinase 1 (DCLK1) as a putative cancer stem cell (CSC) marker has been clarified in colorectal cancer (CRC). Isoform-specific functions of DCLK1 have shed new light on different functions of DCLK1 short (DCLK1-S) and DCLK1 long (DCLK1-L) isoforms in tumor initiation, growth, and metastasis. Therefore, the current systematic review and meta-analysis aimed to review the available in vitro, in vivo, and clinical evidence on the oncogenic roles and clinical significance of DCLK1 isoforms in colorectal cancer.

Methods

The literature databases of PubMed, Scopus, ISI Web of Science, and Embase were searched to identify eligible articles. The description characteristics of in vitro and pre-clinical studies were extracted from identified reports. In addition, hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were recorded to determine the relationships between DCLK1-L and DCLK1-S expression and prognostic outcomes in patients with CRC.

Results

Both in vitro and in vivo evidence have emphasized the potential oncogenic functions of DCLK1 in tumor initiation, self-renewal ability, tumor invasion, epithelial-mesenchymal transition (EMT), and metastasis. However, the anti-DCLK1 antibodies generally utilized in these studies could detect sequence homology epitopes of both isoforms. Recent limited isoform-specific evidence has strongly supported the significant positive expression and rather oncogenic efficacy of DCLK1-S in tumorigenesis, EMT, and invasion compared with DCLK1-L in human CRC cell lines. Our meta-analysis findings of limited clinical studies indicated that only overexpression of DCLK1-S is associated with worse overall survival (OS) (HR = 7.930, 95% CI 2.252–27.924, p = 0.001). Increased expression of both DCLK1-S (HR = 1.610, 95% CI 1.020–2.541, p = 0.041) and DCLK1-L (HR = 5.890, 95% CI 1.219–28.453, p = 0.027) isoforms was closely associated with worse DSS/CSS in CRC patients. Furthermore, the high expression of DCLK1-S was found to be associated with poor DFS/RFS/PFS (HR = 1.913, 95% CI 1.230–2.973, p = 0.004).

Conclusions

The current findings strongly supported that the DCLK1-S isoform may play a crucial role in the invasion, aggressive tumor behavior, and worsened survival outcomes of CRC patients. However, further critical investigations related to the potential preclinical and clinical utilities of DCLK1-S as a specific CRC-CSC marker are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02632-9.

MDSCs might be "Achilles heel" for eradicating CSCs

During tumor initiation and progression, the complicated role of immune cells in the tumor immune microenvironment remains a concern. Myeloid-derived suppressor cells (MDSCs) are a group of immune cells that originate from the bone marrow and have immunosuppressive potency in various diseases, including cancer. In recent years, the key role of cancer stemness has received increasing attention in cancer development and therapy. Several studies have demonstrated the important regulatory relationship between MDSCs and cancer stem cells (CSCs). However, there is still no clear understanding regarding the complex interacting regulation of tumor malignancy, and current research progress is limited. In this review, we summarize the complicated role of MDSCs in the modulation of cancer stemness, evaluate the mechanism of the relationship between CSCs and MDSCs, and discuss potential strategies for eradicating CSCs with respect to MDSCs.

Involvement of Cancer Stem Cells in Chemoresistant Relapse of Epithelial Ovarian Cancer Identified by Transcriptome Analysis

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. Despite the initial resection and chemotherapeutic treatment, relapse is common, which leads to poor survival rates in patients. A primary cause of recurrence is the persistence of ovarian cancer stem cells (OCSCs) with high tumorigenicity and chemoresistance. To achieve a better therapeutic response in EOC relapse, the mechanisms underlying acquired chemoresistance associated with relapse-initiating OCSCs need to be studied. Transcriptomes of both chemosensitive primary and chemoresistant relapse EOC samples were obtained from ICGC OV-AU dataset for differential expression analysis. The upregulated genes were further studied using KEGG and GO analysis. Significantly increased expression of eighteen CSC-related genes was found in chemoresistant relapse EOC groups. Upregulation of the expression in four hub genes including WNT3A, SMAD3, KLF4, and PAX6 was verified in chemoresistant relapse samples via immunohistochemistry staining, which confirmed the existence and enrichment of OCSCs in chemoresistant relapse EOC. KEGG and GO enrichment analysis in microarray expression datasets of isolated OCSCs indicated that quiescent state, increased ability of drug efflux, and enhanced response to DNA damage may have caused the chemoresistance in relapse EOC patients. These findings demonstrated a correlation between OCSCs and acquired chemoresistance and illustrated potential underlying mechanisms of OCSC-initiated relapse in EOC patients. Meanwhile, the differentially expressed genes in OCSCs may serve as novel preventive or therapeutic targets against EOC recurrence in the future.

Niclosamide Ethanolamine Salt Alleviates Idiopathic Pulmonary Fibrosis by Modulating the PI3K-mTORC1 Pathway

Idiopathic pulmonary fibrosis (IPF) is an interstitial pneumonia characterized by chronic progressive fibrosis, ultimately leading to respiratory failure and early mortality. Although not fully explored, the major causative factors in IPF pathogenesis are dysregulated fibroblast proliferation and excessive accumulation of extracellular matrix (ECM) deposited by myofibroblasts differentiated from pulmonary fibroblasts. More signalling pathways, including the PI3K-Akt-mTOR and autophagy pathways, are involved in IPF pathogenesis. Niclosamide ethanolamine salt (NEN) is a highly effective multitarget small-molecule inhibitor reported in antitumor studies. Here, we reported that in an IPF animal model treated with NEN for 14 days, attractive relief of pulmonary function and hydroxyproline content were observed. To further explore, the therapeutic effect of NEN in IPF and pathological changes in bleomycin-challenged mouse lung sections were assessed. Additionally, the effects of NEN on abnormal proliferation and ECM production in IPF cell models established with TGF-β1-stimulated A549 cells or DHLF-IPF cells were studied. In nonclinical studies, NEN ameliorated lung function and histopathological changes in bleomycin-challenged mice, and the lung hydroxyproline content was significantly diminished with NEN treatment. In vitro, NEN inhibited PI3K-mTORC1 signalling and arrested the cell cycle to prevent uncontrolled fibroblast proliferation. Additionally, NEN inhibited TGF-β1-induced epithelial–mesenchymal transition (EMT) and ECM accumulation via the mTORC1-4EBP1 axis. Furthermore, NEN-activated noncanonical autophagy resensitized fibroblasts to apoptosis. The above findings demonstrated the potential antifibrotic effect of NEN mediated via modulation of the PI3K-mTORC1 and autophagy pathways. These data provide strong evidence for a therapeutic role for NEN in IPF.

The Small-Molecule Wnt Inhibitor ICG-001 Efficiently Inhibits Colorectal Cancer Stemness and Metastasis by Suppressing MEIS1 Expression

Recurrence and metastasis remain major obstacles in colorectal cancer (CRC) treatment. Recent studies suggest that a small subpopulation of cells with a self-renewal ability, called cancer stem-like cells (CSCs), promotes recurrence and metastasis in CRC. Unfortunately, no CSC inhibitor has been demonstrated to be more effective than existing chemotherapeutic drugs, resulting in a significant unmet need for effective CRC therapies. In this study, transcriptomic profiling of metastatic tumors from CRC patients revealed significant upregulation in the Wnt pathway and stemness genes. Thus, we examined the therapeutic effect of the small-molecule Wnt inhibitor ICG-001 on cancer stemness and metastasis. The ICG-001 treatment efficiently attenuated self-renewal activity and metastatic potential. Mechanistically, myeloid ecotropic viral insertion site 1 (MEIS1) was identified as a target gene of ICG-001 that is transcriptionally regulated by Wnt signaling. A series of functional analyses revealed that MEIS1 enhanced the CSC behavior and metastatic potential of the CRC cells. Collectively, our findings suggest that ICG-001 efficiently inhibits CRC stemness and metastasis by suppressing MEIS1 expression. These results provide a basis for the further clinical investigation of ICG-001 as a targeted therapy for CSCs, opening a new avenue for the development of novel Wnt inhibitors for the treatment of CRC metastasis.

Emerging insights on functions of the anthelmintic flubendazole as a repurposed anticancer agent

While flubendazole has been used as a macrofilaricide in humans and animals for some 40 years, work in vitro and in preclinical models over the last decade has suggested its potential use as an anticancer agent. This article reviews recent studies in a range of tumor types indicating novel functions for flubendazole in its control of processes associated with tumor growth, spread and renewal including ferroptosis, autophagy, cancer stem-like cell killing and suppression of intratumoral myeloid-derived suppressor cell accumulation and programmed cell death protein 1. Flubendazole's potential use in clinical oncology will require further understanding of its mechanistic roles, range of inhibition of cancer types, capacity for adjunctive therapy and possible reformulation for enhanced solubility, bioavailability and potency.

Lipid raft-disrupting miltefosine preferentially induces the death of colorectal cancer stem-like cells

BACKGROUND

Lipid rafts (LRs), cholesterol-enriched microdomains on cell membranes, are increasingly viewed as signalling platforms governing critical facets of cancer progression. The phenotype of cancer stem-like cells (CSCs) presents significant hurdles for successful cancer treatment, and the expression of several CSC markers is associated with LR integrity. However, LR implications in CSCs remain unclear.

METHODS

This study evaluated the biological and molecular functions of LRs in colorectal cancer (CRC) by using an LR-disrupting alkylphospholipid (APL) drug, miltefosine. The mechanistic role of miltefosine in CSC inhibition was examined through normal or tumour intestinal mouse organoid, human CRC cell, CRC xenograft and miltefosine treatment gene expression profile analyses.

RESULTS

Miltefosine suppresses CSC populations and their self-renewal activities in CRC cells, a CSC-targeting effect leading to irreversible disruption of tumour-initiating potential in vivo. Mechanistically, miltefosine reduced the expression of a set of genes, leading to stem cell death. Among them, miltefosine transcriptionally inhibited checkpoint kinase 1 (CHEK1), indicating that LR integrity is essential for CHEK1 expression regulation. In isolated CD44high CSCs, we found that CSCs exhibited stronger therapy resistance than non-CSC counterparts by preventing cell death through CHEK1-mediated cell cycle checkpoints. However, inhibition of the LR/CHEK1 axis by miltefosine released cell cycle checkpoints, forcing CSCs to enter inappropriate mitosis with accumulated DNA damage and resulting in catastrophic cell death.

CONCLUSION

Our findings underscore the therapeutic potential of LR-targeting APLs for CRC treatment that overcomes the therapy-resistant phenotype of CSCs, highlighting the importance of the LR/CHEK1 axis as a novel mechanism of APLs.

Aberrant activation of the CD45-Wnt signaling axis promotes stemness and therapy resistance in colorectal cancer cells

Rationale: Chemoradiation (CRT) is commonly used as an adjuvant or neoadjuvant treatment for colorectal cancer (CRC) patients. However, resistant cells manage to survive and propagate after CRT, increasing the risk of recurrence. Thus, better understanding the mechanism of resistant cancer cells is required to achieve better clinical outcomes.

Methods: Here, we explored gene expression profiling of CRC patient tumors to identify therapy resistance genes and discovered that protein tyrosine phosphatase receptor type C (PTPRC), which encodes CD45, was increased in remnant tumor tissues after CRT and correlated with metastasis. Through multiple validations using patient tumors and CRC cell lines, we found for the first time the increase of CD45 expression in CRC (EpCAM+) epithelial cells surviving after CRT. Thus, we investigated the biological role and downstream events of CD45 were explored in human CRC cells and CRC mouse models.

Results: Increased CD45 expression in cancer cells in pretreated primary tumors accounts for poor regression and recurrence-free survival in CRT-treated patients. High CD45 expression promotes CRC cell survival upon 5-fluorouracil or radiation treatment, while CD45 depletion sensitizes CRC cells to CRT. Intriguingly, CD45 is preferentially expressed in cancer stem-like cells (CSCs), as determined by spheroid culture and the expression of CSC markers, and is required for the distinct functions of CSCs, such as cancer initiation, repopulation, and metastasis. Mechanistically, CD45 phosphatase activity promotes Wnt transcriptional activity by stabilizing the β-catenin protein, which collectively enhances stemness and the therapy-resistant phenotype.

Conclusions: Our results highlight a novel function of CD45 as a mediator of CRT resistance and provide a potential therapy strategy for CRC therapy.

Research Progress of DCLK1 Inhibitors as Cancer Therapeutics

Doublecortin-like kinase 1 (DCLK1) has emerged over the last decade as a unique stem cell marker within gastrointestinal tissues. Evidence from mouse models shows that high Dclk1 expression denotes a population of cells that promote tissue regeneration and serve as potential cancer stem cells. Moreover, since specific DCLK1 isoforms are overexpressed in many cancers and not normal cells, targeting the expression or kinase activity of DCLK1 can inhibit cancer cell growth. Here we review the evidence for DCLK1 as a prospective cancer target, including its isoform-specific expression and mutational status in human cancers. We further discuss the challenges and current progress in the development of small-molecule inhibitors of DCLK1.

Identifying Novel Actionable Targets in Colon Cancer

Colorectal cancer is the fourth cause of death from cancer worldwide, mainly due to the high incidence of drug-resistance toward classic chemotherapeutic and newly targeted drugs. In the last decade or so, the development of novel high-throughput approaches, both genome-wide and chemical, allowed the identification of novel actionable targets and the development of the relative specific inhibitors to be used either to re-sensitize drug-resistant tumors (in combination with chemotherapy) or to be synthetic lethal for tumors with specific oncogenic mutations. Finally, high-throughput screening using FDA-approved libraries of “known” drugs uncovered new therapeutic applications of drugs (used alone or in combination) that have been in the clinic for decades for treating non-cancerous diseases (re-positioning or re-purposing approach). Thus, several novel actionable targets have been identified and some of them are already being tested in clinical trials, indicating that high-throughput approaches, especially those involving drug re-positioning, may lead in a near future to significant improvement of the therapy for colon cancer patients, especially in the context of a personalized approach, i.e., in defined subgroups of patients whose tumors carry certain mutations.

Targeting the crosstalk between canonical Wnt/β-catenin and inflammatory signaling cascades: A novel strategy for cancer prevention and therapy

Emerging scientific evidence indicates that inflammation is a critical component of tumor promotion and progression. Most cancers originate from sites of chronic irritation, infections and inflammation, underscoring that the tumor microenvironment is largely orchestrated by inflammatory cells and pro-inflammatory molecules. These inflammatory components are intimately involved in neoplastic processes which foster proliferation, survival, invasion, and migration, making inflammation the primary target for cancer prevention and treatment. The influence of inflammation and the immune system on the progression and development of cancer has recently gained immense interest. The Wnt/β-catenin signaling pathway, an evolutionarily conserved signaling strategy, has a critical role in regulating tissue development. It has been implicated as a major player in cancer development and progression with its regulatory role on inflammatory cascades. Many naturally-occurring and small synthetic molecules endowed with inherent anti-inflammatory properties inhibit this aberrant signaling pathway, making them a promising class of compounds in the fight against inflammatory cancers. This article analyzes available scientific evidence and suggests a crosslink between Wnt/β-catenin signaling and inflammatory pathways in inflammatory cancers, especially breast, gastrointestinal, endometrial, and ovarian cancer. We also highlight emerging experimental findings that numerous anti-inflammatory synthetic and natural compounds target the crosslink between Wnt/β-catenin pathway and inflammatory cascades to achieve cancer prevention and intervention. Current challenges, limitations, and future directions of research are also discussed.

The novel driver gene ASAP2 is a potential druggable target in pancreatic cancer

Targeting mutated oncogenes is an effective approach for treating cancer. The 4 main driver genes of pancreatic ductal adenocarcinoma (PDAC) are KRAS, TP53, CDKN2A, and SMAD4, collectively called the "big 4" of PDAC, however they remain challenging therapeutic targets. In this study, ArfGAP with SH3 domain, ankyrin repeat and PH domain 2 (ASAP2), one of the ArfGAP family, was identified as a novel driver gene in PDAC. Clinical analysis with PDAC datasets showed that ASAP2 was overexpressed in PDAC cells based on increased DNA copy numbers, and high ASAP2 expression contributed to a poor prognosis in PDAC. The biological roles of ASAP2 were investigated using ASAP2-knockout PDAC cells generated with CRISPR-Cas9 technology or transfected PDAC cells. In vitro and in vivo analyses showed that ASAP2 promoted tumor growth by facilitating cell cycle progression through phosphorylation of epidermal growth factor receptor (EGFR). A repositioned drug targeting the ASAP2 pathway was identified using a bioinformatics approach. The gene perturbation correlation method showed that niclosamide, an antiparasitic drug, suppressed PDAC growth by inhibition of ASAP2 expression. These data show that ASAP2 is a novel druggable driver gene that activates the EGFR signaling pathway. Furthermore, niclosamide was identified as a repositioned therapeutic agent for PDAC possibly targeting ASAP2.

XMD-17-51 Inhibits DCLK1 Kinase and Prevents Lung Cancer Progression

Doublecortin-like kinase 1 (DCLK1) is a cancer stem cell marker that is highly expressed in various types of human cancer, and a protein kinase target for cancer therapy that is attracting increasing interest. However, no drug candidates targeting DCLK1 kinase have been developed in clinical trials to date. XMD-17-51 was found herein to possess DCLK1 kinase inhibitory activities by cell-free enzymatic assay. In non-small cell lung carcinoma (NSCLC) cells, XMD-17-51 inhibited DCLK1 and cell proliferation, while DCLK1 overexpression impaired the anti-proliferative activity of XMD-17-51 in A549 cell lines. Consequently, XMD-17-51 decreased Snail-1 and zinc-finger-enhancer binding protein 1 protein levels, but increased those of E-cadherin, indicating that XMD-17-51 reduces epithelial-mesenchymal transition (EMT). Furthermore, sphere formation efficiency was significantly decreased upon XMD-17-51 treatment, and XMD-17-51 reduced the expression of stemness markers such as β-catenin, and pluripotency factors such as SOX2, NANOG and OCT4. However, the percentage of ALDH⁺ cells was increased significantly following treatment with XMD-17-51 in A549 cells, possibly due to EMT inhibition. In combination, the present data indicated that XMD-17-51 inhibited DCLK1 kinase activity in a cell-free assay with an IC₅₀ of 14.64 nM, and decreased DCLK1 protein levels, cell proliferation, EMT and stemness in NSCLC cell lines. XMD-17-51 has the potential to be a candidate drug for lung cancer therapy.

Targeting stemness of cancer stem cells to fight colorectal cancers

Cancer initiating/ stem cells (CSCs) undergo self-renewal and differentiation that contributes to tumor initiation, recurrence and metastasis in colorectal cancer (CRC). Targeting of colorectal cancer stem cells (CCSCs) holds significant promise in eradicating cancer cells and ultimately curing patients with cancer. In this review, we will introduce the current progress of CCSC studies, including the specific surface markers of CCSCs, the intrinsic signaling pathways that regulate the stemness and differentiation characteristics of CCSCs, and the tumor organoid model for CCSC research. We will focus on how these studies will lead to the progress in targeting specific surface markers or signaling pathways on CCSCs by monoclonal antibodies, or by natural or synthetic compounds, or by immunotherapy. As CSCs are highly heterogeneous and plastic, we suggest that combinatory approaches that target the stemness network may represent an important strategy for eradicating cancers.

Wnt Signaling in the Tumor Microenvironment

Dysregulated Wnt signaling plays a central role in initiation, progression, and metastasis in many types of human cancers. Cancer development and resistance to conventional cancer therapies are highly associated with the tumor microenvironment (TME), which is composed of numerous stable non-cancer cells, including immune cells, extracellular matrix (ECM), fibroblasts, endothelial cells (ECs), and stromal cells. Recently, increasing evidence suggests that the relationship between Wnt signaling and the TME promotes the proliferation and maintenance of tumor cells, including leukemia. Here, we review the Wnt pathway, the role of Wnt signaling in different components of the TME, and therapeutic strategies for targeting Wnt signaling.

ENC1 Facilitates Colorectal Carcinoma Tumorigenesis and Metastasis via JAK2/STAT5/AKT Axis-Mediated Epithelial Mesenchymal Transition and Stemness

Ectodermal neural cortex 1 (ENC1) is an actin-binding protein and has been known to be upregulated in several cancers, but the molecular mechanisms through which it contributes to the pathology of CRC have largely been elusive. We utilized data mining and validated the aberrant expression of ENC1, following which phenotypic traits of malignancy were assessed in vitro. Ruxolitinib was used as a surrogate to compare the effects of ENC1 expression and silencing on the JAK-STAT-AKT pathway. In vivo models were employed to confirm the in vitro observations. Computation analysis, strengthened by in situ and in vitro data, confirmed the overexpression of ENC1 in CRC and predicted a poor prognosis, while enhanced cell proliferation, invasion, migration, EMT, and stemness were associated with ENC1 overexpression. Silencing of ENC1 downregulated the phenotypes. Additionally, silencing of ENC1 significantly reduced the activation of JAK2 and consequent activation of STAT5 and AKT comparable to ruxolitinib inhibition of JAK2. Silencing of ENC1 resulted in lesser tumor volumes and fewer numbers of tumors, in vivo. These data suggest that ENC1 induces CRC through the JAK2-STAT5-AKT axis. ENC1 is a suitable diagnostic marker for CRC detection, and ENC1 targeting therapies may suppress CRC progression.

Targeting the Wnt/β-catenin signaling pathway in cancer

The aberrant Wnt/β-catenin signaling pathway facilitates cancer stem cell renewal, cell proliferation and differentiation, thus exerting crucial roles in tumorigenesis and therapy response. Accumulated investigations highlight the therapeutic potential of agents targeting Wnt/β-catenin signaling in cancer. Wnt ligand/ receptor interface, β-catenin destruction complex and TCF/β-catenin transcription complex are key components of the cascade and have been targeted with interventions in preclinical and clinical evaluations. This scoping review aims at outlining the latest progress on the current approaches and perspectives of Wnt/β-catenin signaling pathway targeted therapy in various cancer types. Better understanding of the updates on the inhibitors, antagonists and activators of Wnt/β-catenin pathway rationalizes innovative strategies for personalized cancer treatment. Further investigations are warranted to confirm precise and secure targeted agents and achieve optimal use with clinical benefits in malignant diseases.

Role of doublecortin-like kinase 1 and leucine-rich repeat-containing G-protein-coupled receptor 5 in patients with stage II/III colorectal cancer: Cancer progression and prognosis

BACKGROUND

Cancer stem cells (CSCs) are a subpopulation of cancer cells with the potential of self-renewal and differentiation. CSCs play critical roles in tumorigenesis, recurrence, metastasis, radiation tolerance and chemoresistance.

AIM

To assess the expression patterns and clinical potential of doublecortin-like kinase 1 (DCLK1) and leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5), as prognostic CSC markers of colorectal cancer (CRC).

METHODS

The expression of DCLK1 and Lgr5 in CRC tissue sections from 92 patients was determined by immunohistochemistry. Each case was evaluated using a combined scoring method based on signal intensity staining (scored 0-3) and the proportion of positively stained cancer cells (scored 0-3). The final staining score was calculated as the intensity score multiplied by the proportion score. Low expression of DCLK1 and Lgr5 was defined as a score of 0-3; high expression of DCLK1 and Lgr5 was defined as a score of ≥ 4. Specimens were categorized as either high or low expression, and the correlation between the expression of DCLK1 or Lgr5 and clinicopathological factors was investigated.

RESULTS

DCLK1 and Lgr5 expression levels were significantly positively correlated. CRC patients with high DCLK1, Lgr5 and DCLK1/Lgr5 expressions had poorer progression-free survival and overall survival. Moreover, high expression of DCLK1 was an independent prognostic factor for recurrence and overall survival in patients with CRC by multivariate analysis (P = 0.026 and P = 0.049, respectively).

CONCLUSION

DCLK1 may be a potential CSC marker for the recurrence and survival of CRC patients.

Repurposing of niclosamide as a STAT3 inhibitor to enhance the anticancer effect of chemotherapeutic drugs in treating colorectal cancer

AIMS

Colorectal cancer (CRC) is the third most common cancer worldwide. Mutation of various cell signaling molecules or aberrant activation of signaling pathways leads to poor response to chemotherapy in CRC. Signal transducer and activator of transcription protein 3 (STAT3) is an important signaling molecule, which plays crucial roles in regulating cell survival and growth. In this study, the potentitation of chemotherapy by putative STAT3 inhibitors for treating CRC was investigated.

MAIN METHODS

A few putative STAT3 inhibitors were investigated. Niclosamide, originally indicated for the treatment of tapeworm infection, was chosen for further investigation in five CRC cell lines (HCT116, HT29, HCC2998, LoVo and SW480). Western blot analysis was used to evaluate the expression of STAT3/phospho-STAT3 and its downstream targets. Sulforhodamine B assay was used to evaluate the cytotoxicity of drug combinations. Flow cytometric assays were used to investigate the apoptotic and cell cycle effect.

KEY FINDINGS

Niclosamide was found to inhibit expression and activation of STAT3 in a concentration- and time-dependent manner, thereby downregulating STAT3 downstream targets including survivin and cyclin-D1 to induce apoptosis and cell cycle arrest. When combined with niclosamide or specific STAT3 inhibitor (C188-9), the cytotoxicity and DNA damage response from SN38 (the active metabolite from irinotecan) were significantly enhanced. The sequential exposure of SN38 followed by niclosamide was found to be the most potent treatment sequence for the drug combination.

SIGNIFICANCE

Niclosamide represents a promising candidate for repurposing to potentiate the anticancer activity of chemotherapeutic drugs.

Analysis of genomic pathogenesis according to the revised Bethesda guidelines and additional criteria

PURPOSE

As few genotype-phenotype correlations are available for nonsyndromic hereditary colorectal cancer (CRC), we implemented genomic analysis on the basis of the revised Bethesda guideline (RBG) and extended (12 items) to verify possible subtypes.

METHODS

Patients with sporadic CRC (n = 249) were enrolled, stratified according to the revised Bethesda guidelines (RBG+ and RBG- groups) plus additional criteria. Exome/transcriptome analyses (n = 98) and cell-based functional assays were conducted.

RESULTS

We detected 469 somatic and 830 germline gene mutations differing significantly between the positive and negative groups, associated with 12 RBG items/additional criteria. Twenty-one genes had significantly higher mutation rates in left, relative to right, colon cancer, while USP40, HCFC1, and HSPG2 mutation rates were higher in rectal than colon cancer. FAT4 mutation rates were lower in early-onset CRC, in contrast to increased rates in microsatellite instability (MSI)-positive tumors, potentially defining an early-onset microsatellite-stable subtype. The mutation rates of COL6A5 and MGAM2 were significantly and SETD5 was assumably, associated CRC pedigree with concurrent gastric cancer (GC). The predicted deleterious/damaging germline variants, SH2D4A rs35647122, was associated with synchronous/metachronous CRC with related tumors, while NUP160 rs381660 and KRTAP27-1 rs2244485 were potentially associated with a GC pedigree and less strictly defined hereditary CRC, respectively. SH2D4A and NUP160 acted as oncogenic facilitators.

CONCLUSION

Our limited genomic analysis for RBG and additional items suggested that specific somatic alterations in the respective items may enlighten relevant pathogenesis along with the knowledge of germline mutations. Further validation is needed to indicate appropriate surveillance in suspected individuals.

Cinobufagin Suppresses Melanoma Cell Growth by Inhibiting LEF1

Constitutive activation of the β-catenin dependent canonical Wnt signaling pathway, which enhances tumor growth and progression in multiple types of cancer, is commonly observed in melanoma. LEF1 activates β-catenin/TCF4 transcriptional activity, promoting tumor growth and progression. Although several reports have shown that LEF1 is highly expressed in melanoma, the functional role of LEF1 in melanoma growth is not fully understood. While A375, A2058, and G361 melanoma cells exhibit abnormally high LEF1 expression, lung cancer cells express lower LEF1 levels. A luciferase assay-based high throughput screening (HTS) with a natural compound library showed that cinobufagin suppressed β-catenin/TCF4 transcriptional activity by inhibiting LEF1 expression. Cinobufagin decreases LEF1 expression in a dose-dependent manner and Wnt/β-catenin target genes such as Axin-2, cyclin D1, and c-Myc in melanoma cell lines. Cinobufagin sensitively attenuates cell viability and induces apoptosis in LEF1 expressing melanoma cells compared to LEF1-low expressing lung cancer cells. In addition, ectopic LEF1 expression is sufficient to attenuate cinobufagin-induced apoptosis and cell growth retardation in melanoma cells. Thus, we suggest that cinobufagin is a potential anti-melanoma drug that suppresses tumor-promoting Wnt/β-catenin signaling via LEF1 inhibition.

WNT Signaling in Melanoma

WNT-signaling controls important cellular processes throughout embryonic development and adult life, so any deregulation of this signaling can result in a wide range of pathologies, including cancer. WNT-signaling is classified into two categories: β-catenin-dependent signaling (canonical pathway) and β-catenin-independent signaling (non-canonical pathway), the latter can be further divided into WNT/planar cell polarity (PCP) and calcium pathways. WNT ligands are considered as unique directional growth factors that contribute to both cell proliferation and polarity. Origin of cancer can be diverse and therefore tissue-specific differences can be found in WNT-signaling between cancers, including specific mutations contributing to cancer development. This review focuses on the role of the WNT-signaling pathway in melanoma. The current view on the role of WNT-signaling in cancer immunity as well as a short summary of WNT pathway-related drugs under investigation are also provided.

Cysteinyl leukotriene receptor 1 promotes 5-fluorouracil resistance and resistance-derived stemness in colon cancer cells

Colon cancer is a therapy-resistant cancer with a low 5-year survival frequency. The drug 5-fluorouracil (5-FU) has been used as a first-line therapy in metastatic colon cancer in combination with leucovorin or oxaliplatin with a >40% resistance rate. High CysLT₁R expression in tumors is associated with poor survival of colon cancer patients. We sought to examine the role of CysLT₁R in 5-FU resistance and established 5-FU-resistant (5-FU-R) colon cancer cells. These 5-FU-R-cells expressed increased levels of CysLT₁R and showed increased survival and migration compared to nonresistant cells. Increases in thymidylate synthase and active β-catenin were also observed in the 5-FU-R-cells. LTD₄/CysLT₁R signaling was further increased and abolished after CYSLTR1 CRISPR-Cas9-knockdown and reduced in CysLT₁R-doxycycline-knockdown experiments and CysLT₁R-antagonist montelukast/5-FU-treated cells. Montelukast and 5-FU resulted in synergistic effects by reducing HT-29 cell and 5-FU-R-HT-29 cell migration and zebrafish xenograft metastasis. An increase in the stem cell markers in 5-FU-R-cells and 5-FU-R-cell-derived colonospheres and in CysLT₁R-Dox-knockdown cells increased colonosphere formation and stem cell markers was noticed after 5-FU treatment. IL-4-mediated stemness in both HT-29-colonospheres and 5-FU-R-cell derived colonospheres was abolished by montelukast or montelukast + 5-FU-treatment. Targeting CysLT₁R signaling by montelukast might reverse drug resistance and decrease resistance-derived stemness in colon cancer patients.

Self-Renewal Signalling Pathway Inhibitors: Perspectives on Therapeutic Approaches for Cancer Stem Cells

The poor survival and prognosis of individuals with cancer are often attributed to tumour relapse and metastasis, which may be due to the presence of cancer stem cells (CSCs). CSCs have the characteristics of self-renewal, differentiation potential, high carcinogenicity, and drug resistance. In addition, CSCs exhibit many characteristics similar to those of embryonic or tissue stem cells while displaying persistent abnormal activation of self-renewal pathways associated with development and tissue homeostasis, including the Wnt, Notch, Hedgehog (Hh), TGF-β, JAK/STAT3, and NF-κB pathways. Therefore, we can eliminate CSCs by targeting these self-renewal pathways to constrain stem cell replication, survival and differentiation. At the same time, we cannot neglect the ping-pong effect of the tumour microenvironment, which releases cytokines and promotes self-renewal pathways in CSCs. Recently, meaningful progress has been made in the study of inhibitors of self-renewal pathways in tumours. This review primarily summarizes several representative and novel agents targeting these self-renewal signalling pathways and the tumour microenvironment and that represent a promising strategy for treating refractory and recurrent cancer.

The JAK2/STAT3/CCND2 Axis promotes colorectal Cancer stem cell persistence and radioresistance

Background

Radiotherapy (RT) is a highly effective multimodal nonsurgical treatment that is essential for patients with advanced colorectal cancer (CRC). Nevertheless, cell subpopulations displaying intrinsic radioresistance survive after RT. The reactivation of their proliferation and successful colonization at local or distant sites may increase the risk of poor clinical outcomes. Recently, radioresistant cancer cells surviving RT were reported to exhibit a more aggressive phenotype than parental cells, although the underlying mechanisms remain unclear.

Methods

By investigating public databases containing CRC patient data, we explored potential radioresistance-associated signaling pathways. Then, their mechanistic roles in radioresistance were investigated through multiple validation steps using patient-derived primary CRC cells, human CRC cell lines, and CRC xenografts.

Results

Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling was activated in radioresistant CRC tissues in correlation with local and distant metastases. JAK2 was preferentially overexpressed in the CRC stem cell subpopulation, which was accompanied by the phosphorylation of STAT proteins, especially STAT3. JAK2/STAT3 signaling played an essential role in promoting tumor initiation and radioresistance by limiting apoptosis and enhancing clonogenic potential. Mechanistically, the direct binding of STAT3 to the cyclin D2 (CCND2) promoter increased CCND2 transcription. CCND2 expression was required for persistent cancer stem cell (CSC) growth via the maintenance of an intact cell cycle and proliferation with low levels of DNA damage accumulation.

Conclusion

Herein, we first identified JAK2/STAT3/CCND2 signaling as a resistance mechanism for the persistent growth of CSCs after RT, suggesting potential biomarkers and regimens for improving outcomes among CRC patients.

DCLK1 Plays a Metastatic-Promoting Role in Human Breast Cancer Cells

Background

Doublecortin-like kinase 1 (DCLK1) has been universally identified as a cancer stem cell (CSC) marker and is found to be overexpressed in many types of cancers including breast cancer. However, there is little data regarding the functional role of DCLK1 in breast cancer metastasis. In the present study, we sought to investigate whether and how DCLK1 plays a metastatic-promoting role in human breast cancer cells.

Methods

We used Crispr/Cas9 technology to knock out DCLK1 in breast cancer cell line BT474, which basically possesses DCLK1 at a higher level, and stably overexpressed DCLK1 in another breast cancer cell line, T47D, that basically expresses DCLK1 at a lower level. We further analyzed the alterations of metastatic characteristics and the underlying mechanisms in these cells.

Results

It was shown that, compared with the corresponding control cells, DCLK1 overexpression led to an increase in metastatic behaviors including enhanced migration and invasion of T47D cells. By contrast, forced depletion of DCLK1 drastically inhibited these metastatic characteristics in BT474 cells. Mechanistically, the epithelial-mesenchymal transition (EMT) program, which is critical for cancer metastasis, was prominently activated in DCLK1-overexpressing cancer cells, evidenced by a decrease in an epithelial marker ZO-1 and an enhancement in several mesenchymal markers including ZEB1 and Vimentin. In addition, DCLK1 overexpression induced the ERK MAPK pathway, which resultantly enhanced the expression of MT1-MMP that is also involved in cancer metastasis. Knockout of DCLK1 could reverse these events, further supporting a metastatic-promoting role for DCLK1.

Conclusions

Collectively, our data suggested that DCLK1 overexpression may be responsible for the increased metastatic features in breast cancer cells. Targeting DCLK1 may become a therapeutic option for breast cancer metastasis.

Dialysis encephalopathy: precipitating factors and improvement in prognosis

Cancer stem cells (CSCs) contribute to the initiation, recurrence, and metastasis of cancer; however, there are still no drugs targeting CSCs in clinical application. There are several signaling pathways playing critical roles in CSC progression, such as the Wnt, Hedgehog, Notch, Hippo, and autophagy signaling pathways. Additionally, targeting the ferroptosis signaling pathway was recently shown to specifically kill CSCs. Therefore, targeting these pathways may suppress CSC progression. The structure of small-molecule drugs shows a good spatial dispersion, and its chemical properties determine its good druggability and pharmacokinetic properties. These characteristics make small-molecule drugs show a great advantage in drug development, which is increasingly popular in the market. Thus, in this review, we will summarize the current researches on the small-molecule compounds suppressing CSC progression, including inhibitors of Wnt, Notch, Hedgehog, and autophagy pathways, and activators of Hippo and ferroptosis pathways. These small-molecule compounds emphasize CSC importance in tumor progression and propose a new strategy to treat cancer in clinic via targeting CSCs.