RNA-based therapies for colorectal cancer: targeting the β-catenin pathway via microbiota -modulated miRNAs.

The role of JAK/STAT signaling pathway and TNF-α crosstalk in human colorectal cancer

SDF-1/CXCR4 promotes epithelial–mesenchymal transition and progression of colorectal cancer by activation of the Wnt/β-catenin signaling pathway

Tumor specific alterations in miRNA provide ideal biomarkers for early diagnosis of colorectal cancer(CRC). Methylation changes play an important role in the miRNA regulation mechanism involved in tumorigenesis. Therefore, it is important to find miRNA methylation markers related to tumor proliferation and metastasis, and to explore its key regulatory mechanisms. Previous integrated bioinformatics analysis suggested that reduced expression and hypermethation of miR-146a have detected in majority of CRC. However, its biological behavior in CRC remains unclear. This article aims to explore its epigenetic regulation and mechanism in the development of CRC. We collected peripheral blood and tissues from 60 patients with advanced primary CRC, analyzed their clinicopathological characteristics. The mRNA and methylation difference was detected by qPCR and MSP respectively, and the significance in the diagnosis of CRC was analyzed. The research was further confirmed in SW480, SW620, HCT116 and HT29 CRC cell lines, as well as CRC animal models treated with demethylated drugs–5-aza-miR2-oxyeytidineine(5-AZA) and various gene transfection, in order to explore the key downstream regulatory network of miR-146a methylation changes and the effect of methylation inhibitors in the development of CRC. We found that the percentage of down-regulated and methylation of miR-146a in both tissues and plasmas of CRC was significantly higher than that of normal samples, and the expression of miR-146a could be recovered after demethylation treatment in cancer, which was associated with clinical stage. miR-146a methylation was significantly correlated with grading, but not gender, tumor location, histological type or TNM, it may be used as a predictor of poor prognosis. Diagnostic evaluation of miR-146a methylation in tissue and plasma was evaluated using ROC curve, area under regional curve, which indicated that miR-146a methylation could be used as a biomarker for the diagnosis of CRC. Fluorescein report system showed that miR-146a targeted VASN protein, and while miR-146a was overexpressed after transfection into CRC cells, the expression levels of VASN, TGF-β, VEGF-C, MMP9, and Vimentin were significantly reduced, while the expression of TIMP1 and Ecadherin were up-regulated. Additionally, the miR-146a mRNA in CRC tissues was also negatively correlated with the expression of VASN. VASN Silencing down-regulated TGF-β expression, accompanied by a decrease of MMP9. At the same time, after 5-aza demethylation or siVASN, proliferation activity of CRC cells decreased, accompanied by varying degrees of decline in membrane penetrating and migration ability, suggesting that miR-146a may regulate the proliferation and metastasis by regulating VASN/TGF-β relatived pathway. In vivo animal models, it was further confirmed that overexpressed miR-146a was consistent with the effect of 5-aza intervention or siVASN, which could significantly inhibit the occurrence of liver metastasis of CRC. Demethylated drugs treatment or VASN knockdown also significantly inhibited tumor growth in nude mice with CRC. miR-146a was a potential epigenetic silencing tumor suppressor in CRC, and the methylation of miR-146a may play an important role in the diagnosis and prediction of tumor progression in CRC as a new tumor marker. Citation Format: Weiwei Tang, Dan Zhou, Hanxiang An, Jiapeng Kang, Mingquan Cai, Ru Zeng, Jing Song, Bin Hu, Jiabian Lian, Qin Lin, Lilin Chen, Feng Ye. miR-146a methylation regulates proliferation and metastasis by targeted activation of VASN/TGF-beta signaling pathway 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 2443.

Colorectal cancer (CRC) is prevalent with high mortality, with liver metastasis contributing as a major factor that worsens the survival of patients. The roles of miRNAs in CRC have been elucidated, subsequent to recent studies that suggest the involvement of miRNAs in cancer biology. In this study, we compare the miRNA and gene expression profiles of primary tumors between two groups of patients (with and without liver metastasis) to identify the metastasis-initiating microRNA-target gene regulations. Analysis from 33 patients with metastasis and 14 patients without metastasis revealed that 17 miRNAs and their 198 predicted target genes are differentially expressed, where the target genes showed association with cancer progression and metastasis with statistical significance. In order to evaluate the clinical implications of the findings, we classified CRC patients of independent data into two groups based on the identified miRNA-target regulations, where one group was closer to primary tumors with metastasis than the other group. The comparison of survival showed statistically significant difference, thereby implying the roles of the identified miRNA-target regulations in cancer progression and metastasis. The identification of metastasis-initiating miRNA-target regulations in this study will lead to better understanding of the roles of miRNAs in CRC progression.

Simple SummaryColorectal cancer (CRC) is the fourth most common cancer and the second most common cause of cancer-related deaths globally. Rhein is a natural anthraquinone extract from rhubarb, which exhibits potent anticancer activity in various cancers. In this study, we show that rhein significantly inhibited the growth, migration, and invasion of CRC cells by directly binding to mTOR and inhibiting the mTOR signaling pathway. Rhein promotes mTOR degradation through the ubiquitin–proteasome pathway. In addition, rhein significantly suppressed tumor growth in a xenograft mouse model without obvious toxicity. Our results indicate that rhein is a promising anticancer agent that may be useful for the prevention and treatment of CRC.Colorectal cancer (CRC) is one of the leading causes of mortality and morbidity in the world. Rhein has demonstrated therapeutic effects in various cancer models. However, its effects and underlying mechanisms of action in CRC remain poorly understood. We investigated the potential anticancer activity and underlying mechanisms of rhein in CRC in vitro and in vivo. Cell viability and anchorage-independent colony formation assays were performed to examine the antigrowth effects of rhein on CRC cells. Wound-healing and Transwell assays were conducted to assess cell migration and invasion capacity. Cell cycle and apoptosis were investigated by flow cytometry and verified by immunoblotting. A tissue microarray was used to detect mTOR expression in CRC patient tissues. Gene overexpression and knockdown were done to analyze the function of mTOR in CRC. The anticancer effect of rhein in vivo was assessed in a CRC xenograft mouse model. The results show that rhein significantly inhibited CRC cell growth by inducing S-phase cell cycle arrest and apoptosis. Rhein inhibited CRC cell migration and invasion through the epithelial–mesenchymal transition (EMT) process. mTOR was highly expressed in CRC cancer tissues and cells. Overexpression of mTOR promoted cell growth, migration, and invasion, whereas mTOR knockdown diminished these phenomena in CRC cells in vitro. In addition, rhein directly targeted mTOR and inhibited the mTOR signaling pathway in CRC cells. Rhein promoted mTOR degradation through the ubiquitin-proteasome pathway. Intraperitoneal administration of rhein inhibited HCT116 xenograft tumor growth through the mTOR pathway. In conclusion, rhein exerts anticancer activity in vitro and in vivo by targeting mTOR and inhibiting the mTOR signaling pathway in CRC. Our results indicate that rhein is a potent anticancer agent that may be useful for the prevention and treatment of CRC.

Introduction: Colorectal cancer (CRC) frequently harbors KRAS mutations that result in chemoresistance and metastasis. MicroRNAs (miRNAs) are usually dysregulated and play important regulatory roles in tumor progression. However, the KRAS mutation-responsive miRNA profile in CRC remains uninvestigated.Methods: miR-139-5p was identified and evaluated by small RNA sequencing, qRT-PCR and in situ hybridization. The roles of miR-139-5p in CRC cells with and without KRAS mutation were determined by Cell Counting Kit-8 (CCK-8), colony formation, flow cytometry and transwell assays in vitro and by tumorigenesis and metastasis assays in vivo. Microarrays followed by bioinformatic analyses, luciferase reporter assays and Western blotting were applied for mechanistic studies.Results: miR-139-5p was significantly downregulated in KRAS-mutated CRC cells and tissues compared with their wild-type counterparts. Low miR-139-5p expression was associated with aggressive phenotypes and poor prognosis in CRC patients. miR-139-5p overexpression inhibited CRC cell proliferation, migration and invasion in vitro, sensitized tumors to chemotherapy, and impaired tumor growth and metastasis in vivo. Transcriptomic profiling identified multiple modulators in the Ras (JUN and FOS) and Wnt (CTNNB1 and DVL1) signaling pathways and the epithelial-to-mesenchymal transition (EMT) process (ZEB1) as direct targets of miR-139-5p, and inverse correlations were confirmed in CRC clinical tissues. Aberrantly activated Wnt signaling in KRAS-mutant cells was demonstrated to transcriptionally repress miR-139-5p through TCF4, forming a miR-139-5p/Wnt signaling double-negative feedback loop.Conclusions: We identified miR-139-5p as a KRAS-responsive miRNA and demonstrated its involvement in CRC progression. KRAS mutation disrupted the miR-139-5p/Wnt signaling reciprocal negative feedback mechanism, which might cause miR-139-5p downregulation and derepression of oncogenic signaling pathways and EMT. These results reveal a transcriptional regulatory mode of KRAS-driven malignant transformation and highlight miR-139-5p as a novel regulator of crosstalk between the Ras and Wnt signaling pathways in CRC.

Metastasis remains the leading cause of mortality among colorectal cancer (CRC) patients. Identification of new metastasis-related genes are critical to improve colorectal cancer prognosis. Data on mRNA expression in metastatic and primary CRC was obtained from the Gene Expression Omnibus (GEO) database, including GSE81986, GSE41568, GSE71222, GSE21510, and GSE14333. Additionally, data concerning mRNA expression in colon cancer (COAD) and adjacent normal tissues were acquired from The Cancer Genome Atlas (TCGA) database. Hub genes were identified by weighted gene co-expression network analysis (WGCNA) and differential gene expression analysis. Moreover, we assessed the impact of hub gene expression on both overall survival (OS) and disease-free survival (DFS) in patients and identified ZG16 as a potential target. We generated CRC cell lines transfected with lentivirus OE-ZG16 to investigate proliferation, invasion, and migration in vitro. To further elucidate the involvement of ZG16, we utilized gene set enrichment analysis (GSEA) to identify enriched pathways, which were subsequently validated via Western blot analysis. Five datasets containing primary and metastatic CRC samples from GEO database and CRC samples from TCGA database were included in this study and 29 hub genes were identified by WGCNA and differentially expressed gene (DEG) analysis. Low expression of the hub genes (CLCA1 and ZG16) was associated with poor DFS and OS. We confirmed the low expression of ZG16 in CRC using external database and IHC analysis at both transcriptional and protein levels. In addition, the expression of ZG16 was notably elevated in NCM460 cells in comparison to CRC cell lines. The overexpression of ZG16 in CRC cells has been shown to inhibit the proliferation, invasion, and migration of CRC cells. Furthermore, the overexpression of ZG16 has been found to suppress the activation of the epithelial-mesenchymal transition (EMT) and Wnt/β-catenin signaling pathways in CRC. ZG16 may serve as a promising therapeutic target for metastatic CRC treatment.

CRABP2 promotes peritoneal metastasis in CRC through TGF-β/Smad-mediated EMT signaling and invadopodia formation.

The intestinal epithelium acts as a physical barrier that separates the intestinal microbiota from the host and is critical for preserving intestinal homeostasis. The barrier is formed by tightly linked intestinal epithelial cells (IECs) (i.e. enterocytes, goblet cells, neuroendocrine cells, tuft cells, Paneth cells, and M cells), which constantly self-renew and shed. IECs also communicate with microbiota, coordinate innate and adaptive effector cell functions. In this review, we summarize the signaling pathways contributing to intestinal cell fates and homeostasis functions. We focus especially on intestinal stem cell proliferation, cell junction formation, remodelling, hypoxia, the impact of intestinal microbiota, the immune system, inflammation, and metabolism. Recognizing the critical role of KRAS mutants in colorectal cancer, we highlight the connections of KRAS signaling pathways in coordinating these functions. Furthermore, we review the impact of KRAS colorectal cancer mutants on pathway rewiring associated with disruption and dysfunction of the normal intestinal homeostasis. Given that KRAS is still considered undruggable and the development of treatments that directly target KRAS are unlikely, we discuss the suitability of targeting pathways downstream of KRAS as well as alterations of cell extrinsic/microenvironmental factors as possible targets for modulating signaling pathways in colorectal cancer.2BMDrgCx2PNRo1_MkpS-1DVideo

Emerging roles for HMGA2 in colorectal cancer

Epithelial-mesenchymal transition (EMT) is essential for initiation of colorectal cancer (CRC) metastasis, but the diver proteins of EMT remain unclear. Special AT-rich sequence-binding protein 1 (SATB1) was found to be overexpressed in CRC cell lines, and its expression level was positively correlated with CRC progression. Strikingly, EMT process was regulated by SATB1, as SATB1 overexpression upregulated E-cadherin and SATB1 knockdown inhibited N-cadherin cell models. Mechanistically, SATB1 promoted EMT-mediated CRC metastasis via activation of Notch signaling pathway. Taken together, SATB1 plays a vital role in CRC metastasis and may act as a novel prognostic biomarker and a promising therapeutic target for CRC.

Response gene to complement 32 (RGC32) is a transcription factor that regulates the expression of multiple genes involved in cell growth, viability and tissue-specific differentiation. However, the role of RGC32 in tumorigenesis and tumor progression in colorectal cancer (CRC) has not been fully elucidated. Here, we showed that the expression of RGC32 was significantly up-regulated in human CRC tissues versus adjacent normal tissues. RGC32 expression was significantly correlated with invasive and aggressive characteristics of tumor cells, as well as poor survival of CRC patients. We also demonstrated that RGC32 overexpression promoted proliferation, migration and tumorigenic growth of human CRC cells in vitro and in vivo. Functionally, RGC32 facilitated epithelial-mesenchymal transition (EMT) in CRC via the Smad/Sip1 signaling pathway, as shown by decreasing E-cadherin expression and increasing vimentin expression. In conclusion, our findings suggested that overexpression of RGC32 facilitates EMT of CRC cells by activating Smad/Sip1 signaling.

Current evidence suggests that bacteria contribute to the development of certain cancers, such as colorectal cancer (CRC), partly by stimulating chronic inflammation. However, little is known about the bacterial impact on molecular pathways in CRC. Recent studies have demonstrated how specific bacteria can influence the major CRC-related pathways, i.e., Wnt, PI3K-Akt, MAPK, TGF-β, EGFR, mTOR, and p53. In order to advance the current understanding and facilitate the choice of pathways to investigate, we have systematically collected and summarized the current knowledge within bacterial altered major pathways in CRC. Several pro-tumorigenic and anti-tumorigenic bacterial species and their respective metabolites interfere with the major signaling pathways addressed in this review. Not surprisingly, some of these studies investigated known CRC drivers, such as Escherichia coli, Fusobacterium nucleatum, and Bacteroides fragilis. Interestingly, some metabolites produced by bacterial species typically considered pathogenic, e.g., Vibrio cholera, displayed anti-tumorigenic activities, emphasizing the caution needed when classifying healthy and unhealthy microorganisms. The results collectively emphasize the complexity of the relationship between the microbiota and the tumorigenesis of CRC, and future studies should verify these findings in more realistic models, such as organoids, which constitute a promising platform. Moreover, future trials should investigate the clinical potential of preventive modulation of the gut microbiota regarding CRC development.

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers, with high rates of metastasis and lethality. EF-hand domain-containing protein D1 (EFHD1) and salt-inducible kinase 3 (SIK3) have been studied in several cancer types. Aberrant expression of EFHD1 and SIK3 has been observed in CRC, but little research has addressed their regulatory abilities and signaling pathways. In this study, we aimed to explore the efficacy of EFHD1 in inhibiting CRC proliferation and metastasis and to elucidate the underlying mechanisms involved in the upregulation of SIK3 expression. Cell viability, colony formation, wound healing, Transwell assay, orthotopic xenograft, and pulmonary metastasis mouse models were used to detect the antiproliferative and anti-metastatic effects of EFHD1 against CRC in vitro and in vivo. The Gene Expression Profiling Interactive Analysis (GEPIA) database was used to determine EFHD1 and SIK3 expression in CRC. The regulatory roles of EFHD1 and SIK3 in mediating anti-metastatic effects in CRC were measured using western blotting, immunohistochemical, and immunofluorescence analyses. The results showed that EFHD1 expression was significantly repressed in the clinical CRC samples. EFHD1 markedly suppressed cell proliferation, migration, and invasion in vitro and inhibited tumor growth and metastasis in vivo. Analysis of the GEPIA database revealed that EFHD1 expression positively correlated with SIK3 expression. SIK3 overexpression inhibited the migration of CRC cells, and SIK3 knockdown partially eliminated the inhibitory effects of EFHD1 on CRC metastasis. EFHD1 exerted anti-metastatic effects against CRC via upregulating SIK3 and inhibiting epithelial-mesenchymal transition (EMT) processing through modulating the Hippo signaling pathway. Collectively, these findings identify EFHD1 as a potent SIK3 agonist and highlight the EFHD1-SIK3 axis as a key modulator of the Hippo signaling pathway in CRC. EFHD1 serves as a novel regulator and is worthy of further development as a novel therapeutic target in CRC.

Glutamine and glutamate metabolism play crucial roles in the development of various tumors, yet their specific involvement in colorectal cancer (CRC) remains poorly understood. This study aimed investigate the roles of glutamine and glutamate metabolism in CRC progression and to elucidate themolecular mechanisms by which their key regulatory enzyme, GLS1, contributes to CRC development. Blood samples from healthy controls and individuals with colorectal polyp (CRP), colorectal adenoma (CRA), early-stage CRC (ECRC), and advanced CRC (ACRC) were analyzed using liquid chromatography‒mass spectrometry and gas chromatography‒mass spectrometry to quantify metabolite levels. Bioinformatic analyses and molecular experiments were performed to examine GLS1 expression and function in CRC. GLS1 expression was manipulated using siRNAs and lentiviral vectors for knockdown and overexpression, respectively. Functional assays, including CCK-8, Transwell, and colony formation assays, were used to assess the effects of GLS1 on CRC cell proliferation, migration, and invasion. Rescue experiments with rapamycin (autophagy activator) and LY294002 (PI3K inhibitor) were conducted to explore underlying mechanisms. An in vivo tumorigenesis model in nude mice was also established. Patients with ACRC exhibited significantly reduced circulating glutamine levels compared with healthy controls, whereas glutamate levels were elevated across all disease stages (CRP, CRA, ECRC, and ACRC). Circulating glutamine was associated with both CRC diagnosis and prognosis. GLS1 was upregulated in CRC tissues and cell lines and correlated with poor clinical outcomes. Glutamine deprivation and GLS1 knockdown suppressed CRC cell proliferation, migration, and invasion, while GLS1 overexpression enhanced these malignant phenotypes. Bioinformatic analysis revealed that GLS1 activates the PI3K signaling pathway in CRC, which was confirmed by Western blotting following GLS1 knockdown and overexpression. Additionally, glutamine deprivation and GLS1 knockdown induced autophagy in CRC cells, whereas GLS1 overexpression inhibited autophagy, as further evidenced by transmission electron microscopy. Rescue experiments demonstrated that LY294002 and rapamycin reversed the effects of GLS1 on CRC cell proliferation, migration, and invasion . In vivo, GLS1 overexpression promoted tumor growth in nude mice, which was attenuated by LY294002 and rapamycin treatment. Glutamine and glutamate show promise as diagnostic and prognostic biomarkers for CRC. GLS1 plays a critical role in CRC progression by activating the PI3K-AKT signaling pathway and modulating autophagy. These findings provide new insights into glutamine metabolism in CRC and highlight GLS1 as a potential therapeutic target.