Circular RNA PLCE1 promotes epithelial mesenchymal transformation, glycolysis in colorectal cancer and M2 polarization of tumor-associated macrophages

Monotropein attenuates renal cell carcinoma cell progression and M2 macrophage polarization by weakening NF-κB

PURPOSE

The study aimed to investigate the effect and mechanism of monotropein on renal cell carcinoma (RCC).

METHODS

After monotropein and NF-κB receptor activator (RANKL) treatment, cell proliferation, invasion, and apoptosis were evaluated using CCK-8, Transwell, and flow cytometry. Primary macrophages co-cultured with monotropein-treated RCC cells were analyzed to evaluate macrophage polarization using qRT-PCR, western blot, and ELISA assays by detecting the expression of M2 markers (CD206, CD168) and cytokines (IL-10, TGF-β). Additionally, the therapeutic efficacy of monotropein was examined using an RCC mouse xenograft model.

RESULTS

Monotropein could inhibit the proliferation, invasion, and M2 macrophage polarization and accelerate the apoptosis of RCC cells. Mechanistically, monotropein suppressed NF-κB pathway activation in RCC cells and reduced the expression of NF-κB downstream targets, including Bcl-2, c-Myc, and MMP9. RANKL could eliminate the effect of monotropein on RCC progression. In primary macrophages co-cultured with monotropein-treated RCC cells, monotropein downregulated M2 polarization markers and cytokines, further supporting its role in modulating the tumor microenvironment. In mouse models, monotropein reduced RCC tumor growth, induced apoptosis, and blocked NF-κB pathway.

CONCLUSIONS

Monotropein prevents RCC malignant progression and reduces M2 macrophage polarization by suppressing the NF-κB pathway, suggesting that monotropein may serve as a potential therapeutic agent for RCC by targeting both tumor cells and the tumor microenvironment.

Circular RNAs perspective: exploring the direction of immunotherapy for colorectal cancer

Circular RNAs (circRNAs) are multifaceted molecules that play a pivotal role in regulating gene expression at both transcriptional and post-transcriptional levels. Their expression is highly tissue-specific and developmentally regulated, making them critical players in various physiological processes and diseases, particularly cancer. In colorectal cancer, circRNAs exhibit significantly dysregulated expression patterns and profoundly influence disease progression through diverse molecular mechanisms. Unraveling the complex roles of circRNAs in modulating colorectal cancer immunotherapy outcomes highlights their potential as both promising biomarkers and therapeutic targets. Moving forward, advancements in circRNA-based therapeutic strategies and delivery systems are poised to transform precision medicine, enabling early colorectal cancer diagnosis and improving patient prognosis.

CircRNAs in Colorectal Cancer: Unveiling Their Roles and Exploring Therapeutic Potential

Colorectal cancer (CRC) is the most common malignancy of the digestive system. Although research into the causes of CRC's origin and progression has advanced over the past few decades, many details are still not fully understood. Circular RNAs (circRNAs), as a novel regulatory molecule, have been found to be closely involved in various key biological processes in CRC. CircRNAs also have been shown to encode proteins, which could offer new possibilities for therapeutic applications. This ability to produce tumor-specific proteins makes circRNA-based vaccines a potentially valuable approach for targeted cancer treatment. In this review, we summarize recent findings on the various roles of circRNAs in CRC and explore their potential in the development of protein-encoding circRNA vaccines for CRC therapy.

Circular RNAs as key regulators in cancer hallmarks: New progress and therapeutic opportunities

Circular RNAs (circRNAs) have emerged as critical regulators in cancer biology, contributing to various cancer hallmarks, including cell proliferation, apoptosis, metastasis, and drug resistance. Defined by their covalently closed loop structure, circRNAs possess unique characteristics like high stability, abundance, and tissue-specific expression. These non-coding RNAs function through mechanisms such as miRNA sponging, interactions with RNA-binding proteins (RBPs), and modulating transcription and splicing. Advances in RNA sequencing and bioinformatics tools have enabled the identification and functional annotation of circRNAs across different cancer types. Clinically, circRNAs demonstrate high specificity and sensitivity in samples, offering potential as diagnostic and prognostic biomarkers. Additionally, therapeutic strategies involving circRNA mimics, inhibitors, and delivery systems are under investigation. However, their precise mechanisms remain unclear, and more clinical evidence is needed regarding their roles in cancer hallmarks. Understanding circRNAs will pave the way for novel diagnostic and therapeutic approaches, potentially improving patient outcomes.

Biological roles and molecular mechanism of circular RNAs in epithelial-mesenchymal transition of gastrointestinal malignancies

Circular RNAs (circRNAs) are formed by splicing of precursor RNAs and covalently linked at the 5' and 3' ends. Dysregulated circRNAs are closely related to the epithelial-mesenchymal transition (EMT) of gastrointestinal malignancies. CircRNAs, including circRNA_0008717, circGOT1, circ-DOCK5, circVPS33B, circPVT1, circMET, circ-OXCT1, circ_67835, circRTN4, circ_0087502, circFNDC38, circ_PTEN1, circPGPEP1, and circ-E-Cad are involved in the EMT process of gastrointestinal malignancies through a variety of mechanisms, such as regulating EMT-inducing transcription factors, signaling pathways, and tumor microenvironments. Gastrointestinal (GI) malignancies are common malignant tumors worldwide, and the heterogeneity and easy metastasis of gastrointestinal malignancies limit the effectiveness of medical treatments. Therefore, investigating the molecular mechanisms involved in the pathogenesis of gastrointestinal malignancies is essential for clinical treatment. This article summarizes the biological roles and molecular mechanism of circRNAs in EMT of gastrointestinal malignancies, providing a theoretical basis for applying EMT-related circRNAs in targeted therapy.

Emerging roles of CircRNA-miRNA networks in cancer development and therapeutic response

The complex interplay of epigenetic factors is essential in regulating the hallmarks of cancer and orchestrating intricate molecular interactions during tumor progression. Circular RNAs (circRNAs), known for their covalently closed loop structures, are non-coding RNA molecules exceptionally resistant to enzymatic degradation, which enhances their stability and regulatory functions in cancer. Similarly, microRNAs (miRNAs) are endogenous non-coding RNAs with linear structures that regulate cellular biological processes akin to circRNAs. Both miRNAs and circRNAs exhibit aberrant expressions in various cancers. Notably, circRNAs can function as sponges for miRNAs, influencing their activity. The circRNA/miRNA interaction plays a pivotal role in the regulation of cancer progression, including in brain, gastrointestinal, gynecological, and urological cancers, influencing key processes such as proliferation, apoptosis, invasion, autophagy, epithelial-mesenchymal transition (EMT), and more. Additionally, this interaction impacts the response of tumor cells to radiotherapy and chemotherapy and contributes to immune evasion, a significant challenge in cancer therapy. Both circRNAs and miRNAs hold potential as biomarkers for cancer prognosis and diagnosis. In this review, we delve into the circRNA-miRNA circuit within human cancers, emphasizing their role in regulating cancer hallmarks and treatment responses. This discussion aims to provide insights for future research to better understand their functions and potentially guide targeted treatments for cancer patients using circRNA/miRNA-based strategies.

Exploring the impact of circRNAs on cancer glycolysis: Insights into tumor progression and therapeutic strategies

Cancer cells exhibit altered metabolic pathways, prominently featuring enhanced glycolytic activity to sustain their rapid growth and proliferation. Dysregulation of glycolysis is a well-established hallmark of cancer and contributes to tumor progression and resistance to therapy. Increased glycolysis supplies the energy necessary for increased proliferation and creates an acidic milieu, which in turn encourages tumor cells' infiltration, metastasis, and chemoresistance. Circular RNAs (circRNAs) have emerged as pivotal players in diverse biological processes, including cancer development and metabolic reprogramming. The interplay between circRNAs and glycolysis is explored, illuminating how circRNAs regulate key glycolysis-associated genes and enzymes, thereby influencing tumor metabolic profiles. In this overview, we highlight the mechanisms by which circRNAs regulate glycolytic enzymes and modulate glycolysis. In addition, we discuss the clinical implications of dysregulated circRNAs in cancer glycolysis, including their potential use as diagnostic and prognostic biomarkers. All in all, in this overview, we provide the most recent findings on how circRNAs operate at the molecular level to control glycolysis in various types of cancer, including hepatocellular carcinoma (HCC), prostate cancer (PCa), colorectal cancer (CRC), cervical cancer (CC), glioma, non-small cell lung cancer (NSCLC), breast cancer, and gastric cancer (GC). In conclusion, this review provides a comprehensive overview of the significance of circRNAs in cancer glycolysis, shedding light on their intricate roles in tumor development and presenting innovative therapeutic avenues.

Emerging Roles of Circular RNA in Macrophage Activation and Inflammatory Lung Responses

Circular RNA (circRNA) is a type of single-stranded RNA that forms a covalently closed continuous loop, unlike linear RNA. The expression of circRNAs in mammals is often conserved across species and shows tissue and cell specificity. Some circRNA serve as gene regulators. However, the biological function of most circRNAs is unclear. CircRNA does not have 5' or 3' ends. The unique structure of circRNAs provides them with a much longer half-life and more resistance to RNase R than linear RNAs. Inflammatory lung responses occur in the pathogenesis and recovery of many lung diseases. Macrophages form the first line of host defense/innate immune responses and initiate/mediate lung inflammation. For example, in bacterial pneumonia, upon pro-inflammatory activation, they release early response cytokines/chemokines that recruit neutrophils, macrophages, and lymphocytes to sites of infection and clear pathogens. The functional effects and mechanisms by which circRNAs exert physiological or pathological roles in macrophage activation and lung inflammation remain poorly understood. In this article, we will review the current understanding and progress of circRNA biogenesis, regulation, secretion, and degradation. Furthermore, we will review the current reports on the role of circRNAs in macrophage activation and polarization, as well as in the process of inflammatory lung responses.

PDIA3 driven STAT3/PD-1 signaling promotes M2 TAM polarization and aggravates colorectal cancer progression

OBJECTIVE

This inquiry endeavors to delineate the influence of PDIA3 on tumor-associated macrophages within the realm of colorectal malignancies, whilst elucidating the intrinsic biochemical pathways.

METHOD

Leveraging bioinformatics, we scrutinized the symbiosis between PDIA3, STAT3, and CD274. A xenograft model in immunodeficient murine served to assess PDIA3's impact on colorectal carcinogenesis. Further, Western blot analysis quantified the protein expression of PDIA3, p-STAT3, PD-1, XBP-1, assorted enzymes, and IL-6. Moreover, in vitro assays gauged SW480 cellular dynamics inclusive of migration, invasive potential, and proliferation.

RESULTS

Bioinformatics exploration exposed PDIA3's elevated presence in diverse cancers, with a marked expression in colorectal cancer, as per TCGA and GEO repositories. Correlative studies showed PDIA3 positively aligning with STAT3 and CD274, the latter also associated with monocyte-derived macrophages. Comparative analysis of colorectal neoplasms and normal colon samples unveiled heightened levels of PDIA3 markers which, when overexpressed in SW480 cells, escalated tumorigenicity and oncogenic behaviors, with a noted decrease upon PD-1 monoclonal antibody intervention.

CONCLUSIONS

PDIA3 augments the M2 polarization of tumor-associated macrophages via modulation of the STAT3/PD-1 cascade, thus invigorating the tumorous proliferation and dissemination in colorectal cancer. Such revelations position PDIA3 as an auspicious target for PD-1 blockade therapeutics, offering a promising foundation for rectifying colorectal carcinoma.

Association between Metabolic Reprogramming and Immune Regulation in Digestive Tract Tumors

BACKGROUND

The cancers of the digestive tract, including colorectal cancer (CRC), gastric cancer, and esophageal cancer, are part of the most common cancers as well as one of the most important leading causes of cancer death worldwide.

SUMMARY

Despite the emergence of immune checkpoint inhibitors (e.g., anti-CTLA-4 and anti-PD-1/PD-L1) in the past decade, offering renewed optimism in cancer treatment, only a fraction of patients derive benefit from these therapies. This limited efficacy may stem from tumor heterogeneity and the impact of metabolic reprogramming on both tumor cells and immune cells within the tumor microenvironment (TME). The metabolic reprogramming of glucose, lipids, amino acids, and other nutrients represents a pivotal hallmark of cancer, serving to generate energy, reducing equivalent and biological macromolecule, thereby fostering tumor proliferation and invasion. Significantly, the metabolic reprogramming of tumor cells can orchestrate changes within the TME, rendering patients unresponsive to immunotherapy.

KEY MESSAGES

In this review, we predominantly encapsulate recent strides on metabolic reprogramming among digestive tract cancer, especially CRC, in the TME with a focus on how these alterations influence anti-tumor immunity. Additionally, we deliberate on potential strategies to address these abnormities in metabolic pathways and the viability of combined therapy within the realm of anti-cancer immunotherapy.

Communication molecules (ncRNAs) mediate tumor-associated macrophage polarization and tumor progression

Non-coding RNAs play important roles in tumor cells and macrophages and participate in their communication as messengers. Non-coding RNAs have an impact in tumor cell proliferation, migration, and apoptosis, and they also regulate the differentiation and regulation of immune cells. In macrophages, they stimulate the polarization of macrophages into M1 or M2 by regulating proteins related to signaling pathways; in tumor cells, non-coding RNAs can enter macrophages through exosomes and affect the latter polarization. The polarization of macrophages further regulates the biological functions of cancer cells. The direction of macrophage polarization determines tumor progression, angiogenesis and drug resistance. This often creates a feedback loop. Non-coding RNAs act as bridges between tumor cells and macrophages to regulate the balance of the tumor microenvironment. We reviewed the signaling pathways related to macrophage polarization and the regulatory mechanisms of non-coding RNA in tumor-associated macrophages M1 and M2, and discussed the potential applications and prospects of exosome engineering.

Pharmacogenomic and epigenomic approaches to untangle the enigma of IL-10 blockade in oncology

The host immune system status remains an unresolved mystery among several malignancies. An immune-compromised state or smart immune-surveillance tactics orchestrated by cancer cells are the primary cause of cancer invasion and metastasis. Taking a closer look at the tumour-immune microenvironment, a complex network and crosstalk between infiltrating immune cells and cancer cells mediated by cytokines, chemokines, exosomal mediators and shed ligands are present. Cytokines such as interleukins can influence all components of the tumour microenvironment (TME), consequently promoting or suppressing tumour invasion based on their secreting source. Interleukin-10 (IL-10) is an interlocked cytokine that has been associated with several types of malignancies and proved to have paradoxical effects. IL-10 has multiple functions on cellular and non-cellular components within the TME. In this review, the authors shed the light on the regulatory role of IL-10 in the TME of several malignant contexts. Moreover, detailed epigenomic and pharmacogenomic approaches for the regulation of IL-10 were presented and discussed.

Glycolysis in human cancers: Emphasis circRNA/glycolysis axis and nanoparticles in glycolysis regulation in cancer therapy

The metabolism of cancer has been an interesting hallmark and metabolic reprogramming, especially the change from oxidative phosphorylation in mitochondria to glucose metabolism known as glycolysis occurs in cancer. The molecular profile of glycolysis, related molecular pathways and enzymes involved in this mechanism such as hexokinase have been fully understood. The glycolysis inhibition can significantly decrease tumorigenesis. On the other hand, circRNAs are new emerging non-coding RNA (ncRNA) molecules with potential biological functions and aberrant expression in cancer cells which have received high attention in recent years. CircRNAs have a unique covalently closed loop structure which makes them highly stable and reliable biomarkers in cancer. CircRNAs are regulators of molecular mechanisms including glycolysis. The enzymes involved in the glycolysis mechanism such as hexokinase are regulated by circRNAs to modulate tumor progression. Induction of glycolysis by circRNAs can significantly increase proliferation rate of cancer cells given access to energy and enhance metastasis. CircRNAs regulating glycolysis can influence drug resistance in cancers because of theirimpact on malignancy of tumor cells upon glycolysis induction. TRIM44, CDCA3, SKA2 and ROCK1 are among the downstream targets of circRNAs in regulating glycolysis in cancer. Additionally, microRNAs are key regulators of glycolysis mechanism in cancer cells and can affect related molecular pathways and enzymes. CircRNAs sponge miRNAs to regulate glycolysis as a main upstream mediator. Moreover, nanoparticles have been emerged as new tools in tumorigenesis suppression and in addition to drug and gene delivery, then mediate cancer immunotherapy and can be used for vaccine development. The nanoparticles can delivery circRNAs in cancer therapy and they are promising candidates in regulation of glycolysis, its suppression and inhibition of related pathways such as HIF-1α. The stimuli-responsive nanoparticles and ligand-functionalized ones have been developed for selective targeting of glycolysis and cancer cells, and mediating carcinogenesis inhibition.

Circular RNAs with protein-coding ability in oncogenesis

As ubiquitously expressed transcripts in eukaryotes, circular RNAs (circRNAs) are covalently closed and lack a 5'-cap and 3'-polyadenylation (poly (A)) tail. Initially, circRNAs were considered non-coding RNA (ncRNA), and their roles as sponging molecules to adsorb microRNAs have been extensively reported. However, in recent years, accumulating evidence has demonstrated that circRNAs could encode functional polypeptides through the initiation of translation mediated by internal ribosomal entry sites (IRESs) or N6-methyladenosine (m6A). In this review, we collectively discuss the biogenesis, cognate mRNA products, regulatory mechanisms, aberrant expression and biological phenotypes or clinical relevance of all currently reported, cancer-relevant protein-coding circRNAs. Overall, we provide a comprehensive overview of circRNA-encoded proteins and their physiological and pathological functions.

Circular RNAs as the pivotal regulators of epithelial-mesenchymal transition in gastrointestinal tumor cells

Gastrointestinal (GI) cancers, as the most common human malignancies are always considered one of the most important health challenges in the world. Late diagnosis in advanced tumor stages is one of the main reasons for the high mortality rate and treatment failure in these patients. Therefore, investigating the molecular pathways involved in GI tumor progression is required to introduce the efficient markers for the early tumor diagnosis. Epithelial-mesenchymal transition (EMT) is one of the main cellular mechanisms involved in the GI tumor metastasis. Non-coding RNAs (ncRNAs) are one of the main regulatory factors in EMT process. Circular RNAs (circRNAs) are a group of covalently closed loop ncRNAs that have higher stability in body fluids compared with other ncRNAs. Considering the importance of circRNAs in regulation of EMT process, in the present review we discussed the role of circRNAs in EMT process during GI tumor invasion. It has been reported that circRNAs mainly affect the EMT process through the regulation of EMT-specific transcription factors and signaling pathways such as WNT, PI3K/AKT, TGF-β, and MAPK. This review can be an effective step in introducing a circRNA/EMT based diagnostic panel marker for the early tumor detection among GI cancer patients.

CircRNAs: emerging factors for regulating glucose metabolism in colorectal cancer

Colorectal cancer is a malignant disease with a high incidence and low survival rate, and the effectiveness of traditional treatments, such as surgery and radiotherapy, is very limited. CircRNAs, a kind of stable endogenous circular RNA, generally function by sponging miRNAs and binding or translating proteins. CircRNAs have been identified to play an important role in regulating the proliferation and metabolism of CRC. In recent years, many reports have indicated that by regulating the expression of glycolysis-related proteins, such as GLUT1 and HK2, or directly translating proteins, circRNAs can promote the Warburg effect in cancer cells, thereby driving CRC metabolism. Moreover, the Warburg effect increases lactate production in cancer cells and promotes acidification of the TME, which further drives cancer progression. In this review, we summarized the remarkable role of circRNAs in regulating glucose metabolism in CRC in recent years, which might be useful for finding new targets for the clinical treatment of CRC.

Regulation of the tumor immune microenvironment by cancer-derived circular RNAs

Circular RNA (circRNAs) is a covalently closed circular non-coding RNA formed by reverse back-splicing from precursor messenger RNA. It is found widely in eukaryotic cells and can be released to the surrounding environment and captured by other cell types. This, circRNAs serve as connections between different cell types for the mediation of multiple signaling pathways. CircRNAs reshape the tumor microenvironment (TME), a key factor involved in all stages of cancer development, by regulating epithelial-stromal transformation, tumor vascularization, immune cell function, and inflammatory responses. Immune cells are the most abundant cellular TME components, and they have profound toxicity to cancer cells. This review summarizes circRNA regulation of immune cells, including T cells, natural killer cells, and macrophages; highlights the impact of circRNAs on tumor progression, treatment, and prognosis; and indicates new targets for tumor immunotherapy.

circ-ZEB1 regulates epithelial-mesenchymal transition and chemotherapy resistance of colorectal cancer through acting on miR-200c-5p

Circular RNAs (circRNAs) have been demonstrated to be important regulators in human malignant tumors, including colorectal cancer (CRC). While the role circ-ZEB1 played in CRC remains unclear. In this study, we aim to explore the biological function and the underlying mechanism of circ-ZEB1 in CRC. RNAscope was used to analyze the expression and localization of circ-ZEB1 in CRC tissues. Loss of function experiments were conducted, including CCK-8, transwell assays, flow cytometry analysis, and murine xenograft models, so as to detect the effect of circ-ZEB1 on CRC cells. IC50 assay was used to evaluate the influence of circ-ZEB1 on the chemoresistance of CRC cells. Epithelial-mesenchymal transition (EMT) related markers were detected. The relationship between circ-ZEB1 and miR-200c-5p was investigated by FISH, dual-luciferase reporter assay, and RIP assay. We found in our study that circ-ZEB1 was significantly upregulated in CRC tissues. Downregulation of circ-ZEB1 inhibited cell proliferation, colony formation, as well as cell migration and invasion abilities of CRC cell lines. In vivo experiments indicated that knockdown of circ-ZEB1 suppressed tumorigenesis and distant metastasis of CRC cells in nude mice. What's more, EMT and chemoresistance of CRC cells were also attenuated following circ-ZEB1 knockdown. Mechanistically, we proved that circ-ZEB1 could directly bind with miR-200c and functioned as miR-200c sponge to exert its biological functions in CRC cells. In conclusion, circ-ZEB1 could promote CRC cells progression, EMT, and chemoresistance via acting on miR-200c, elucidating a potential therapeutic target to inhibit CRC progression.

EMR1/ADGRE1 Expression in Cancer Cells Upregulated by Tumor-Associated Macrophages Is Related to Poor Prognosis in Colorectal Cancer

EMR1, a member of the adhesion G protein-coupled receptor family (ADGRE1), is a macrophage marker that is abnormally expressed in cancer cells. However, its clinical significance in colorectal cancer (CRC) is not well-known. In this investigation, EMR1 expression in tumor cells (EMR1-TC) was found in 91 (22.8%) of the 399 CRC samples tested by immunohistochemical staining and showed a significant relationship with lymph node metastasis. Furthermore, EMR1-TC was significantly associated with CD68⁺ CD163⁺ tumor-associated macrophages (TAMs), and CRC with a high combined EMR1-TC⁺CD68⁺CD163⁺ score showed worse recurrence-free survival prognosis. In an in vitro co-culture assay of colon cancer cells with myeloid cells, we found that EMR1 expression significantly upregulated in cancer cells was induced by macrophages. In addition, there was increased expression of M2 markers (CD163 and interleukin-6 & 10) in myeloid portion, while that of M1 markers (CD86 and iNOS) remained unchanged. Accordingly, upon treatment with M2 macrophage polarization inhibitors (O-ATP, trametinib, bardoxolone methyl), EMR1 expression reduced significantly, along with M2 markers (CD163 and interleukin-6 & 10). In conclusion, EMR1-TC was a high-risk factor for lymph node metastasis and correlated with poor recurrence free survival, particularly in patients with TAM-rich CRC. Furthermore, EMR1 expression in colon cancer cells may be related to M2 macrophage polarization and vice versa.

MiR-216b targets CPEB4 to suppress colorectal cancer progression through inhibiting IL-10-mediated M2 polarization of tumor-associated macrophages

OBJECTIVES

The M2 polarization of tumor-associated macrophages (TAMs) facilitates the growth, invasion and metastasis of tumor cells. Here, we investigated the role of miR-216b in the M2 polarization of TAMs in colorectal cancer (CRC).

METHODS

The expression of genes were examined by quantitative real-time polymerase chain reaction, Western blot, enzyme-linked immunosorbent assay and immunohistochemistry. The relationship between miR-216b and CPEB4 was verified through dual luciferase reporter assays. The proliferation, migration and invasiveness of CRC and Raw264.7 cells were assessed through cell counting kit-8 and Transwell assays. Flow cytometry was used to quantify the percentage of F4/80+/CD206+RAW264.7 cells. The metastasis of tumor cells in liver and lung tissues was evaluated by establishing a mouse xenograft tumor model and hematoxylin-eosin staining.

RESULTS

Downregulation of miR-216b enhanced the M2 polarization of TAMs. CPEB4 was identified as a target of miR-216b. CPEB4 knockdown suppressed CRC cell proliferation, migration and invasion, which were rescued by miR-216b inhibition. It was confirmed that M2 macrophage infiltration in CRC was positively correlated with the expression levels of CPEB4 and IL-10. CPEB4 knockdown impaired the M2 polarization of Raw264.7 cells and reduced IL-10 expression. miR-216b overexpression suppressed tumor growth, metastasis and expressions of CPEB4, CD206 and IL-10 in CRC xenograft models.

CONCLUSIONS

miR-216b targets CPEB4 to impair the IL-10-mediated M2 polarization of TAMs, thereby inhibiting CRC development.

SLC11A1 associated with tumor microenvironment is a potential biomarker of prognosis and immunotherapy efficacy for colorectal cancer

Colorectal cancer (CRC) is one of the most lethal cancers of the digestive system. The tumor microenvironment (TME) plays a central role in the initiation and development of CRC. However, little is known about the modulation mechanism of the TME in CRC. In our study, we attempted to identify a biomarker related to the TME modulation that could serve as a potential prognostic biomarker for CRC. We identified differentially expressed genes between the ImmuneScore high/low and StromalScore high/low groups. Using univariate COX regression analysis and hub gene analysis (cytoHubba), SLC11A1 was identified as the only candidate gene for subsequent analysis. CIBERSORT, EPIC, MCPcounter, and immunogenic cell death were performed to evaluate the effect of SLC11A1 on the TME. We also collected samples and performed Real-time quantitative PCR to verify the expression levels of SLC11A1 in CRC and adjacent normal tissues. The IMvigor210 cohort, TIDE score, and immunophenoscore (IPS) were used to analyze the association between SLC11A1 and immunotherapy efficacy. SLC11A1 was highly expressed in CRC tissues compared with its expression in normal colorectal tissues and was associated with poor prognosis and advanced clinicopathological stages. Gene set enrichment analysis showed that TGF-β pathways, JAK-STAT pathways, and angiogenesis were significantly enriched in the high-SLC11A1 group. Single-cell analysis validated the correlation between SLC11A1 and the TME. Using CIBERSORT, EPIC, and MCPcounter algorithms, we found that there was more macrophage and fibroblast infiltration in the SLC11A1 high-expression group. Meanwhile, high-SLC11A1 patients had lower IPS scores, higher TIDE scores, and fewer immunotherapy benefits than those of low-SLC11A1 patients. In conclusion, SLC11A1 plays a crucial role in the TME and could serve as a potential biomarker for poor prognosis and immunotherapy efficacy in CRC.

Recent Advances in the Study of Extracellular Vesicles in Colorectal Cancer

There has been significant progress in the study of extracellular vesicles (EVs) since the 2017 American Gastroenterological Association-sponsored Freston Conference "Extracellular Vesicles: Biology, Translation and Clinical Application in GI Disorders." The burgeoning interest in this field stems from the increasing recognition that EVs represent an understudied form of cell-to-cell communication and contain cargo replete with biomarkers and therapeutic targets. This short review will highlight recent advances in the field, with an emphasis on colorectal cancer. After a brief introduction to secreted particles, we will describe how our laboratory became interested in EVs, which led to refined methods of isolation and identification of 2 secreted nanoparticles. We will then summarize the cargo found in small EVs released from colorectal cancer cells and other cells in the tumor microenvironment, as well as those found in the circulation of patients with colorectal cancer. Finally, we will consider the continuing challenges and future opportunities in this rapidly evolving field.

Emerging role of non-coding RNAs in glucose metabolic reprogramming and chemoresistance in colorectal cancer

Metabolic reprogramming plays a critical role in colorectal cancer (CRC). It contributes to CRC by shaping metabolic phenotypes and causing uncontrolled proliferation of CRC cells. Glucose metabolic reprogramming is common in carcinogenesis and cancer progression. Growing evidence has implicated the modifying effects of non-coding RNAs (ncRNAs) in glucose metabolic reprogramming and chemoresistance in CRC. In this review, we have summarized currently published studies investigating the role of ncRNAs in glucose metabolic alterations and chemoresistance in CRC. Elucidating the interplay between ncRNAs and glucose metabolic reprogramming provides insight into exploring novel biomarkers for the diagnosis and prognosis prediction of CRC.

Past, Present and Future: The Relationship Between Circular RNA and Immunity

The immune system has evolved since the birth of humans. However, immune-related diseases have not yet been overcome due to the lack of expected indicators and targeting specificity of current medical technology, subjecting patients to very uncomfortable physical and mental experiences and high medical costs. Therefore, the requirements for treatments with higher specificity and indicative ability are raised. Fortunately, the discovery of and continuous research investigating circular RNAs (circRNAs) represent a promising method among numerous methods. Although circRNAs wear regarded as metabolic wastes when discovered, as a type of noncoding RNA (ncRNA) with a ring structure and wide distribution range in the human body, circRNAs shine brilliantly in medical research by virtue of their special nature and structure-determined functions, such as high stability, wide distribution, high detection sensitivity, acceptable reproducibility and individual differences. Based on research investigating the role of circRNAs in immunity, we systematically discuss the hotspots of the roles of circRNAs in immune-related diseases, including expression profile analyses, potential biomarker research, ncRNA axis/network construction, impacts on phenotypes, therapeutic target seeking, maintenance of nucleic acid stability and protein binding research. In addition, we summarize the current situation of and problems associated with circRNAs in immune research, highlight the applications and prospects of circRNAs in the treatment of immune-related diseases, and provide new insight into future directions and new strategies for laboratory research and clinical applications.

Lactate-related metabolic reprogramming and immune regulation in colorectal cancer

Changes in cellular metabolism involving fuel sources are well-known mechanisms of cancer cell differentiation in the context of carcinogenesis. Metabolic reprogramming is regulated by oncogenic signaling and transcriptional networks and has been identified as an essential component of malignant transformation. Hypoxic and acidified tumor microenvironment contributes mainly to the production of glycolytic products known as lactate. Mounting evidence suggests that lactate in the tumor microenvironment of colorectal cancer(CRC) contributes to cancer therapeutic resistance and metastasis. The contents related to the regulatory effects of lactate on metabolism, immune response, and intercellular communication in the tumor microenvironment of CRC are also constantly updated. Here we summarize the latest studies about the pleiotropic effects of lactate in CRC and the clinical value of targeting lactate metabolism as treatment. Different effects of lactate on various immune cell types, microenvironment characteristics, and pathophysiological processes have also emerged. Potential specific therapeutic targeting of CRC lactate metabolism is also discussed. With increased knowledge, effective druggable targets might be identified, with the aim of improving treatment outcomes by reducing chemoresistance.