Tumor Microenvironment Of Colorectal Cancer Research Articles

Resveratrol: biology, metabolism, and detrimental role on the tumor microenvironment of colorectal cancer.

A substantial increase in colorectal cancer (CRC)-associated fatalities can be attributed to tumor recurrence and multidrug resistance. Traditional treatment options, including radio- and chemotherapy, also exhibit adverse side effects. Ancient treatment strategies that include phytochemicals like resveratrol are now widely encouraged as an alternative therapeutic option. Resveratrol is the natural polyphenolic stilbene in vegetables and fruits like grapes and apples. It inhibits CRC progression via targeting dysregulated cancer-promoting pathways, including PI3K/Akt/Kras, targeting transcription factors like NF-κB and STAT3, and an immunosuppressive tumor microenvironment. In addition, combination therapies for cancer include resveratrol as an adjuvant to decrease multidrug resistance that develops in CRC cells. The current review discusses the biology of resveratrol and explores different mechanisms of action of resveratrol in inhibiting CRC progression. Further, the detrimental role of resveratrol on the immunosuppressive tumor microenvironment of CRC has been discussed. This review illustrates clinical trials on resveratrol in different cancers, including resveratrol analogs, and their efficiency in promoting CRC inhibition.

TIM-3 Expression and M2 Polarization of Macrophages in the TGFβ-Activated Tumor Microenvironment in Colorectal Cancer.

TGFβ signaling in the tumor microenvironment (TME) drives immune evasion and is a negative predictor of immune checkpoint inhibitor (ICI) efficacy in colorectal cancer (CRC). TIM-3, an inhibitory receptor implicated in anti-tumor immune responses and ICI resistance, has emerged as an immunotherapeutic target. This study investigated TIM-3, M2 macrophages and the TGFβ-activated TME, in association with microsatellite instability (MSI) status and consensus molecular subtypes (CMSs). Transcriptomic cohorts of CRC tissues, organoids and xenografts were examined (n = 2240). TIM-3 and a TGFβ-inducible stromal protein, VCAN, were evaluated in CRC specimens using immunohistochemistry (n = 45). TIM-3 expression on monocytes and generated M2 macrophages was examined by flow cytometry. We found that the expression of HAVCR2 (TIM-3) significantly correlated with the transcriptional signatures of TGFβ, TGFβ-dependent stromal activation and M2 macrophage, each of which were co-upregulated in CMS4, CMS1 and MSI CRCs across all datasets. Tumor-infiltrating TIM-3+ immune cells accumulated in TGFβ-responsive cancer stroma. TIM-3 was increased on M2-polarized macrophages, and on monocytes in response to TGFβ treatment. In conclusion, we identified a close association between TIM-3 and M2-like polarization of macrophages in the TGFβ-rich TME. Our findings provide new insights into personalized immunotherapeutic strategies based on the TME for CRCs.

Differential gene expression of immunity and inflammation genes in colorectal cancer using targeted RNA sequencing.

Colorectal cancer (CRC) is a heterogeneous disease caused by molecular changes, as driver mutations, gene methylations, etc., and influenced by tumor microenvironment (TME) pervaded with immune cells with both pro- and anti-tumor effects. The studying of interactions between the immune system (IS) and the TME is important for developing effective immunotherapeutic strategies for CRC. In our study, we focused on the analysis of expression profiles of inflammatory and immune-relevant genes to identify aberrant signaling pathways included in carcinogenesis, metastatic potential of tumors, and association of Kirsten rat sarcoma virus (KRAS) gene mutation. A total of 91 patients were enrolled in the study. Using NGS, differential gene expression analysis of 11 tumor samples and 11 matching non-tumor controls was carried out by applying a targeted RNA panel for inflammation and immunity genes containing 475 target genes. The obtained data were evaluated by the CLC Genomics Workbench and R library. The significantly differentially expressed genes (DEGs) were analyzed in Reactome GSA software, and some selected DEGs were used for real-time PCR validation. After prioritization, the most significant differences in gene expression were shown by the genes TNFRSF4, IRF7, IL6R, NR3CI, EIF2AK2, MIF, CCL5, TNFSF10, CCL20, CXCL11, RIPK2, and BLNK. Validation analyses on 91 samples showed a correlation between RNA-seq data and qPCR for TNFSF10, RIPK2, and BLNK gene expression. The top differently regulated signaling pathways between the studied groups (cancer vs. control, metastatic vs. primary CRC and KRAS positive and negative CRC) belong to immune system, signal transduction, disease, gene expression, DNA repair, and programmed cell death. Analyzed data suggest the changes at more levels of CRC carcinogenesis, including surface receptors of epithelial or immune cells, its signal transduction pathways, programmed cell death modifications, alterations in DNA repair machinery, and cell cycle control leading to uncontrolled proliferation. This study indicates only basic molecular pathways that enabled the formation of metastatic cancer stem cells and may contribute to clarifying the function of the IS in the TME of CRC. A precise identification of signaling pathways responsible for CRC may help in the selection of personalized pharmacological treatment.

A WGCNA-based cancer-associated fibroblast risk signature in colorectal cancer for prognosis and immunotherapy response.

Cancer-associated fibroblasts (CAFs) are notably involved in colorectal cancer (CRC) tumorigenesis, progression, and treatment failure. In this article, we report the in silico development of a CAF-related prognostic signature for CRC. We separately downloaded CRC transcription data from The Cancer Genome Atlas and the Gene Expression Omnibus database. Deconvolution algorithms, including Estimating the Proportions of Immune and Cancer Cells and the Microenvironment Cell Population-counter, were used to calculate CAF abundance, while the Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression algorithm was used to calculate the stromal score. Weighted gene co-expression network analysis (WGCNA) and the least absolute shrinkage and selection operator algorithm were used to identify CAF-related genes and prognostic signatures. We identified a three-gene, prognostic, CAF-related signature and defined risk groups based on the Riskscores. Multidimensional validations were applied to evaluate the robustness of the signature and its correlation with clinical parameters. We utilized Tumor Immune Dysfunction and Exclusion (TIDE) and oncoPredict algorithms to predict therapy responses and found that patients in low-risk groups are more sensitive to immunotherapy and chemotherapy drugs such as 5-fluorouracil and oxaliplatin. Finally, we used the Cancer Cell Line Encyclopedia and Human Protein Atlas databases to evaluate the mRNA and protein levels encoded by the signature genes. This novel CAF-related three-gene signature is expected to become a potential prognostic biomarker in CRC and predict chemotherapy and immunotherapy responses. It may be of considerable value for studying the tumor microenvironment in CRC.

Exosome-derived miR-372-5p promotes stemness and metastatic ability of CRC cells by inducing macrophage polarization

Colorectal cancer (CRC) is the most common malignancy in the digestive system, and tumor metastasis is the main cause of death in clinical patients with CRC. It has been shown that exosomes promote phenotypic changes in macrophages and tumor metastasis in the CRC tumor microenvironment. In this study, we used miRNA-seq technology to screen out the highly expressed miR-372-5p among the miRNAs differentially expressed in plasma exosomes of clinical CRC patients. It was found that miR-372-5p highly expressed in HCT116 exosomes could be phagocytosed by macrophages and promote their polarization into M2 macrophages by regulating the PTEN/AKT pathway. Meanwhile, co-culture of CRC cells with conditioned medium (CM) of macrophages enhanced the EMT, stemness and metastasis of CRC cells. Mechanistically, CRC cells exosome-derived miR-372-5p induced polarized M2 macrophages to secrete chemokine C-X-C-Motif Ligand 12 (CXCL12), which activated the WNT/β-catenin pathway to promote the EMT, stemness and metastatic ability of CRC cells. In summary, this study elucidated the molecular mechanism of exosomal miR-372-5p promoting metastasis and stemness in CRC, which may provide new therapeutic targets for CRC metastasis and prognosis assessment.

Exploring the potential mechanisms of Yi-Yi-Fu-Zi-Bai-Jiang-San therapy on the immune-inflamed phenotype of colorectal cancer via combined network pharmacology and bioinformatics analyses

BackgroundThe development and progression of colorectal cancer (CRC) is closely associated with its complex tumor microenvironment (TME). Assessment of the modified pattern of immune cell infiltration (ICI) will help increase knowledge regarding the characteristics of TME infiltration. Yi-Yi-Fu-Zi-Bai-Jiang-San (YYFZBJS) has been shown to have positive effects on the regulation of the immune microenvironment of CRC. However, its pharmacological targets and molecular mechanisms remain to be elucidated. MethodsNetwork pharmacological analysis was used to identify the target of YYFZBJS in the TME of CRC. Patients with the immune-inflamed phenotype (IIP) were identified using CRC samples from The Cancer Genome Atlas (TCGA) database. Consensus genes were identified by intersecting YYFZBJS targets, CRC disease targets and differentially expressed genes in the CRC microenvironment. Then, least absolute shrinkage and selection operator (LASSO) Cox analyses were used to identify a prognostic signature from the consensus genes. Cytoscape software was further used to build a unique herb–compound–target network diagram of the important components of YYFZBJS and prognostic gene targets. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was performed using the prognostic gene sets to explore the molecular mechanism of the prognostic genes in drug therapy for CRC IIP patients. Finally, single-cell analysis was performed to validate the expression of the prognostic genes in the TME of CRC using the TISCH2 database. ResultsA total of 284 IIP patients were identified from 480 patients with CRC. A total of 35 consensus genes were identified as targets of YYFZBJS in the TME of CRC patients. An eleven-gene prognostic signature, including PIK3CG, C5AR1, PRF1, CAV1, HPGDS, PTGS2, SERPINE1, IDO1, TGFB1, CXCR2 and MMP9, was identified from the consensus genes, with areas under the receiver operating characteristic (ROC) curve (AUCs) values of 0.84 and 0.793 for the training and test cohorts, respectively. In the herb–compound–target network, twenty-four compounds were shown to interact with the 11 prognostic genes, which were significantly enriched in the IL-17 signaling, arachidonic acid metabolism and metabolic pathways. Single-cell analysis of the prognostic genes confirmed that their abnormal expression was associated with the TME of CRC. ConclusionThis study organically integrated network pharmacology and bioinformatics analyses to identify prognostic genes in CRC IIP patients from the targets of YYFZBJS. Although this data mining work was limited to the study of mechanisms related to prognosis based on the immune microenvironment, the methodology provides new perspectives in the search for novel therapeutic targets of traditional Chinese medicines (TCMs) and accurate diagnostic indicators of cancers targeted by TCMs.

Multi-Faceted Role of Cancer-Associated Adipocytes in Colorectal Cancer.

Colorectal cancer (CRC) is one of the most commonly diagnosed types of cancer, especially in obese patients, and the second cause of cancer-related death worldwide. Based on these data, extensive research has been performed over the last decades to decipher the pivotal role of the tumor microenvironment (TME) and its cellular and molecular components in CRC development and progression. In this regard, substantial progress has been made in the identification of cancer-associated adipocytes' (CAAs) characteristics, considering their active role in the CCR tumor niche, by releasing a panel of metabolites, growth factors, and inflammatory adipokines, which assist the cancer cells' development. Disposed in the tumor invasion front, CAAs exhibit a fibroblastic-like phenotype and establish a bidirectional molecular dialogue with colorectal tumor cells, which leads to functional changes in both cell types and contributes to tumor progression. CAAs also modulate the antitumor immune cells' response and promote metabolic reprogramming and chemotherapeutic resistance in colon cancer cells. This review aims to report recent cumulative data regarding the molecular mechanisms of CAAs' differentiation and their activity spectrum in the TME of CRC. A better understanding of CAAs and the molecular interplay between CAAs and tumor cells will provide insights into tumor biology and may open the perspective of new therapeutic opportunities in CRC patients.

Bacterial lipopolysaccharide modulates immune response in the colorectal tumor microenvironment

Immune responses can have opposing effects in colorectal cancer (CRC), the balance of which may determine whether a cancer regresses, progresses, or potentially metastasizes. These effects are evident in CRC consensus molecular subtypes (CMS) where both CMS1 and CMS4 contain immune infiltrates yet have opposing prognoses. The microbiome has previously been associated with CRC and immune response in CRC but has largely been ignored in the CRC subtype discussion. We used CMS subtyping on surgical resections from patients and aimed to determine the contributions of the microbiome to the pleiotropic effects evident in immune-infiltrated subtypes. We integrated host gene-expression and meta-transcriptomic data to determine the link between immune characteristics and microbiome contributions in these subtypes and identified lipopolysaccharide (LPS) binding as a potential functional mechanism. We identified candidate bacteria with LPS properties that could affect immune response, and tested the effects of their LPS on cytokine production of peripheral blood mononuclear cells (PBMCs). We focused on Fusobacterium periodonticum and Bacteroides fragilis in CMS1, and Porphyromonas asaccharolytica in CMS4. Treatment of PBMCs with LPS isolated from these bacteria showed that F. periodonticum stimulates cytokine production in PBMCs while both B. fragilis and P. asaccharolytica had an inhibitory effect. Furthermore, LPS from the latter two species can inhibit the immunogenic properties of F. periodonticum LPS when co-incubated with PBMCs. We propose that different microbes in the CRC tumor microenvironment can alter the local immune activity, with important implications for prognosis and treatment response.

Tumor microenvironment characterization in colorectal cancer to identify prognostic and immunotherapy genes signature

BackgroundThe tumor microenvironment (TME) plays a crucial role in tumorigenesis, progression, and therapeutic response in many cancers. This study aimed to comprehensively investigate the role of TME in colorectal cancer (CRC) by generating a TMEscore based on gene expression.MethodsThe TME patterns of CRC datasets were investigated, and the TMEscores were calculated. An unsupervised clustering method was used to divide samples into clusters. The associations between TMEscores and clinical features, prognosis, immune score, gene mutations, and immune checkpoint inhibitors were analyzed. A TME signature was constructed using the TMEscore-related genes. The results were validated using external and clinical cohorts.ResultsThe TME pattern landscape was for CRC was examined using 960 samples, and then the TMEscore pattern of CRC datasets was evaluated. Two TMEscore clusters were identified, and the high TMEscore cluster was associated with early-stage CRC and better prognosis in patients with CRC when compared with the low TMEscore clusters. The high TMEscore cluster indicated elevated tumor cell scores and tumor gene mutation burden, and decreased tumor purity, when compared with the low TMEscore cluster. Patients with high TMEscore were more likely to respond to immune checkpoint therapy than those with low TMEscore. A TME signature was constructed using the TMEscore-related genes superimposing the results of two machine learning methods (LASSO and XGBoost algorithms), and a TMEscore-related four-gene signature was established, which had a high predictive value for discriminating patients from different TMEscore clusters. The prognostic value of the TMEscore was validated in two independent cohorts, and the expression of TME signature genes was verified in four external cohorts and clinical samples.ConclusionOur study provides a comprehensive description of TME characteristics in CRC and demonstrates that the TMEscore is a reliable prognostic biomarker and predictive indicator for patients with CRC undergoing immunotherapy.

S3-CIMA: Supervised spatial single-cell image analysis for identifying disease-associated cell-type compositions in tissue

The spatial organization of various cell types within the tissue microenvironment is a key element for the formation of physiological and pathological processes, including cancer and autoimmune diseases. Here, we present S3-CIMA, a weakly supervised convolutional neural network model that enables the detection of disease-specific microenvironment compositions from high-dimensional proteomic imaging data. We demonstrate the utility of this approach by determining cancer outcome- and cellular-signaling-specific spatial cell-state compositions in highly multiplexed fluorescence microscopy data of the tumor microenvironment in colorectal cancer. Moreover, we use S3-CIMA to identify disease-onset-specific changes of the pancreatic tissue microenvironment in type 1 diabetes using imaging mass-cytometry data. We evaluated S3-CIMA as a powerful tool to discover novel disease-associated spatial cellular interactions from currently available and future spatial biology datasets.

Fibroblast activation protein-α expression in fibroblasts is common in the tumor microenvironment of colorectal cancer and may serve as a therapeutic target.

Background: Colorectal cancer (CRC) is still one of the leading causes of cancer death worldwide, emphasizing the need for further diagnostic and therapeutic approaches. Cancer invasion and metastasis are affected by the tumor microenvironment (TME), with cancer-associated fibroblasts (CAF) being the predominant cellular component. An important marker for CAF is fibroblast activation protein-α (FAP) which has been evaluated as therapeutic target for, e.g., radioligand therapy. The aim of this study was to examine CRC regarding the FAP expression as a candidate for targeted therapy. Methods: 67 CRC, 24 adenomas, 18 tissue samples of inflammation sites and 28 non-neoplastic, non-inflammatory tissue samples of colonic mucosa were evaluated for immunohistochemical FAP expression of CAF in tissue microarrays. The results were correlated with clinicopathological data, tumor biology and concurrent expression of additional immunohistochemical parameters. Results: 53/67 (79%) CRC and 6/18 (33%) inflammatory tissue specimens showed expression of FAP. However, FAP was only present in 1/24 (4%) adenomas and absent in normal mucosa (0/28). Thus, FAP expression in CRC was significantly higher than in the other investigated groups. Within the CRC cohort, expression of FAP did not correlate with tumor stage, grading or the MSI status. However, it was observed that tumors exhibiting high immunohistochemical expression of Ki-67, CD3, p53, and β-Catenin showed a significantly higher incidence of FAP expression. Conclusion: In the crosstalk between tumor cells and TME, CAF play a key role in carcinogenesis and metastatic spread. Expression of FAP was detectable in the majority of CRC but nearly absent in precursor lesions and non-neoplastic, non-inflammatory tissue. This finding indicates that FAP has the potential to emerge as a target for new diagnostic and therapeutic concepts in CRC. Additionally, the association between FAP expression and other immunohistochemical parameters displays the interaction between different components of the TME and demands further investigation.

Tumor-infiltrating gamma delta T-cells reveal exhausted subsets with remarkable heterogeneity in colorectal cancer.

The γδT-cells recognize infected or transformed cells. However, unlike αβT-cells, γδT-cells are innate-like immune cells, with no major histocompatibility complex restriction requirements. γδT-cells are the main population of intestinal intraepithelial lymphocytes (IELs) and are associated with the antitumor immune response, particularly in colorectal cancer (CRC). Although CD8+ T-cells exhibit dysfunction and even exhaustion in the tumor microenvironment (TME), which contributes to tumor immune escape, whether the same applies to tumor-infiltrating (TI)-γδT-cells is not completely understood. Here, we sought to investigate the expression pattern of inhibitory receptors and functional state of TI-γδT-cells, and reveal the features of exhausted TI-γδT-cells in the CRC TME. We demonstrated that TI-γδT-cells exhibited exhaustion phenotypes and displayed more severe functional exhaustion than TI-CD8+ T-cells or NK-cells in the TME of CRC. In addition, scRNA-seq analysis of TI-γδT-cells revealed three exhausted subsets with remarkable heterogeneity. The presence of three heterogeneous exhausted γδT-cell (Tex) populations, including Texprog , Textran and Texterm were further confirmed by flow cytometry, on the basis of PD-1 and TIM-3 expression. Finally, we revealed that c-Maf not only contributed to γδT-cell exhaustion via upregulation of inhibitory receptors, but also involved in the exhaustion of CD8+ T and NK-cells. c-Maf may also be an important contributor to γδT-cell exhaustion in CRC patients. These findings indicated that TI-γδT-cells exhibit phenotypic and functional exhaustion in the CRC TME. The revealed features of exhausted TI-γδT-cells may provide help for understanding the mechanisms and the association of γδT-cell exhaustion with tumor development and pathogenesis.

Bifidobacterium adolescentis orchestrates CD143+ cancer-associated fibroblasts to suppress colorectal tumorigenesis by Wnt signaling-regulated GAS1.

The interplay between gut microbiota and tumor microenvironment (TME) in the pathogenesis of colorectal cancer (CRC) is not well explored. Here, we elucidated the functional role of Bifidobacterium adolescentis (B.a) on CRC and investigated its possible mechanism on the manipulation of cancer-associated fibroblasts (CAFs) in CRC. Different CRC animal models and various cell line models were established to explore the function of B.a on CRC. The single-cell RNA sequencing (scRNA-seq) or flow cytometry was used to detect the cell subsets in the TME of CRC. Western blot, quantitative real-time polymerase chain reaction (qRT-PCR), or immunofluorescence staining were performed to examine the activation of Wnt signaling and growth arrest specific 1 (GAS1) on CD143+ CAFs. Chromatin immunoprecipitation quantitative real-time PCR (CHIP-qPCR) was performed to investigate the regulation of transcription factor 4 (TCF4) on GAS1. Multi-immunofluorescence assay examined the expression level of CD143 and GAS1 on tissue microarray. We found that B.a abundance was significantly reduced in CRC patients from two independent cohorts and the bacteria database of GMrepo. Supplementation with B.a suppressed ApcMin/+ spontaneous or AOM/DSS-induced tumorigenesis in mice. scRNA-seq revealed that B.a facilitated a subset of CD143+ CAFs by inhibiting the infiltration of Th2 cells, while promoting the TNF-alpha+ B cells in TME. CD143+ CAFs highly expressed GAS1 and exhibited tumor suppressive effect. Mechanistically, GAS1 was activated by the Wnt/β-catenin signaling in CD143+ CAFs. B.a abundance was correlated with the expression level of CD143 and GAS1. The level of CD143+ CAFs predicted the better survival outcome in CRC patients. These results highlighted that B.a induced a new subset of CD143+ CAFs by Wnt signaling-regulated GAS1 to suppress tumorigenesis and provided a novel therapeutic target for probiotic-based modulation of TME in CRC.

Abnormal genetic and epigenetic patterns of m6A regulators associated with tumor microenvironment in colorectal cancer.

N6-methyladenosine (m6A) has a critical role in the development and progression of cancer. However, the genetic and epigenetic patterns, as well as tumor microenvironment (TME) infiltration characteristics of m6A regulators in colorectal cancer (CRC) remain largely unknown. Molecular patterns of m6A modifications of 24 m6A regulators in CRC samples were evaluated using data from The Cancer Genome Atlas (TCGA). Mutations, copy number variations (CNVs), DNA methylation, and chromatin accessibility were examined to investigate the underlying mechanisms of the aberrant expression of m6A regulators. Correlations between m6A-related genes and TME cell-infiltrating characteristics were evaluated using Tumor Immune Estimation Resource (TIMER). The m6A regulators were frequently dysregulated in CRC, with two downregulated and 16 upregulated. All the m6A regulators had mutations (frequency ranging from 0.9% to 7%), with active mutations tending to occur in RBM15 and inactive mutations in ZC3H13. Only five m6A regulators had CNV frequency greater than 1%: YTHDC2 (2.4%), YTHDF1 (7.0%), YTHDF3 (1.9%), VIRMA (1.7%), and ZC3H13 (3.0%). The copy numbers of these five genes were positively correlated with their expression levels. The m6A regulators frequently showed imbalanced methylation in CRC, with hypomethylation of YTHDF2, IGF2BP3, FTO, and hypermethylation of HNRNPC, METTL3, and WTAP. Most m6A regulators had high chromatin accessibility, which was positively correlated with their gene expression. IGF2BP1 was identified as an independent prognostic factor for overall survival. Moreover, the expression of most m6A regulators was positively correlated with the infiltration of B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells. Aberrant expression of m6A regulators is associated with mutation, CNV, and chromatin accessibility, owing to both genetic and epigenetic modifications. The TME infiltration characterization of m6A regulators could guide the development of more effective immunotherapy strategies in CRC.

Deep immunophenotyping reveals clinically distinct cellular states and ecosystems in large-scale colorectal cancer

Determining the diverse cell types in the tumor microenvironment (TME) and their organization into cellular communities, is critical for understanding the biological heterogeneity and therapy of cancer. Here, we deeply immunophenotype the colorectal cancer (CRC) by integrative analysis of large-scale bulk and single cell transcriptome of 2350 patients and 53,137 cells. A rich landscape of 42 cellular states and 7 ecosystems in TMEs is uncovered and extend the previous immune classifications of CRC. Functional pathways and potential transcriptional regulators analysis of cellular states and ecosystems reveal cancer hallmark-related pathways and several critical transcription factors in CRC. High-resolution characterization of the TMEs, we discover the potential utility of cellular states (i.e., Monocytes/Macrophages and CD8 T cell) and ecosystems for prognosis and clinical therapy selection of CRC. Together, our results expand our understanding of cellular organization in TMEs of CRC, with potential implications for the development of biomarkers and precision therapies.

Resveratrol induces apoptosis by modulating the reciprocal crosstalk between p53 and Sirt-1 in the CRC tumor microenvironment.

P53 represents a key player in apoptosis-induction in cancers including colorectal cancer (CRC) that ranks third worldwide in cancer prevalence as well as mortality statistics. Although a pro-apoptotic effect of resveratrol has been repeatedly proven in CRC cells, its pathway mechanisms are not completely understood, as there are controversial statements in the literature regarding its activation or inhibition of the counteracting proteins Sirt-1 and p53. CRC cells as wild-type (HCT-116 WT) or p53-deficient (HCT-116 p53-/-) were cultured using multicellular tumor microenvironment (TME) cultures containing T-lymphocytes and fibroblasts to elucidate the role of p53/Sirt-1 modulation in resveratrol's concentration-dependent, pro-apoptotic, and thus anti-cancer effects. Resveratrol dose-dependently inhibited viability, proliferation, plasticity as well as migration, and induced apoptosis in HCT-116 WT more effectively than in HCT-116 p53-/- cells. Moreover, resveratrol stimulated Sirt-1 expression when administered at low concentrations (<5µM) but suppressed it when added at high concentrations (>10µM) to CRC-TME. In parallel, similar to the knockdown of Sirt-1 at the mRNA level, treatment with high-concentration resveratrol boosted the acetylation of p53, the expression of p21, Bax, cytochrome C, caspase-3, and ultimately induced apoptosis in CRC WT but not in CRC p53-/- cells. Notably, increasing concentrations of resveratrol were found to promote hyperacetylation of p53 and FOXO3a as post-translational substrates of Sirt-1, indicating a negative regulatory loop between Sirt-1 and p53. These results demonstrate for the first time, a negative reciprocal crosstalk between the regulatory circuits of p53 and Sirt-1, consequently, apoptosis induction by higher resveratrol concentrations in CRC-TME.

M5C regulator-mediated methylation modification phenotypes characterized by distinct tumor microenvironment immune heterogenicity in colorectal cancer.

The RNA 5-methylcytosine (m5C) modification has been demonstrated to be an important epigenetic regulator and to impact colorectal cancer (CRC) progression. However, the potential roles of m5C modification in immune cell infiltration in the CRC tumor microenvironment (TME) remain unknown. The m5C modification phenotypes were comprehensively evaluated based on 14 m5C regulators in a meta-CRC cohort of 1792 patients and systematically correlated with the m5C modification phenotypes, immune cell infiltration characteristics and known biological processes. The m5Cscore model was constructed by principal component analysis (PCA) algorithms to quantify the m5C modification phenotypes of individual CRC samples and was used to predict the immunotherapy response. We identified three m5C modification phenotypes associated with distinct clinical outcomes and biological processes among the 1792 meta-CRC patients. Three phenotypes with a highly consistent TME landscape and characteristics were revealed: immune excluded, immune desert and immune inflammation. The meta-CRC patients were divided into high and low m5Cscore subgroups based on the m5Cscore. The m5Cscore was confirmed to have a negative correlation with infiltrating immune cells and PD-L1 expression and a positive correlation with tumor mutation burden (TMB), mutation rate and microsatellite instability (MSI) score. Moreover, patients in the low m5Cscore group had better immunotherapy responses and significant durable survival benefits in independent anti-PD-1/L1 immunotherapy cohorts for the immune checkpoint inhibitor (ICI) therapeutic strategy. This study revealed that m5C modification plays a crucial role in TME composition and complexity. Comprehensive evaluation of the m5C modification phenotypes of individual patients will enhance our understanding of TME characteristics and promote the application of more appropriate and personalized treatment strategies.

Expression of Immune-Related and Inflammatory Markers and Their Prognostic Impact in Colorectal Cancer Patients.

The tumor microenvironment of colorectal cancer (CRC) is heterogenous; thus, it is likely that multiple immune-related and inflammatory markers are simultaneously expressed in the tumor. The aim of this study was to identify immune-related and inflammatory markers expressed in freshly frozen CRC tissues and to investigate whether they are related to the clinicopathological features and prognosis of CRC. Seventy patients with CRC who underwent curative surgical resection between December 2014 and January 2017 were included in this study. Tissue samples were obtained from tumor and non-tumor areas in the patients' colons. The concentrations of immune-related markers (APRIL/TNFSF13, BAFF, LAG-3, PD-1, PD-L1, and CTLA-4) and inflammatory markers (CHIT, MMP-3, osteocalcin, pentraxin-3, sTNF-R1, and sTNF-R2) in the samples were measured using the Bio-plex Multiplex Immunoassay system. The concentrations of APRIL/TNFSF13, BAFF, and MMP-3 in the samples were significantly high; thus, we conducted analyses based on the cut-off values for these three markers. The high-APRIL/TNFSH13-expression group showed a significantly higher rate of metastatic lesions than the low-expression group, whereas the high-MMP-3-expression group had higher CEA levels, more lymph node metastases, and more advanced disease stages than the low-expression group. The five-year disease-free survival of the high-MMP-3-expression group was significantly shorter than that of the low-expression group (65.1% vs. 90.2%, p = 0.033). This study provides evidence that the APRIL/TNFSF13, BAFF, and MMP-3 pathway is overexpressed in CRC tissues and is associated with unfavorable clinicopathological features and poor prognosis in CRC patients. These markers could serve as diagnostic or prognostic biomarkers for CRC.

Using Machine Learning Methods to Study Colorectal Cancer Tumor Micro-Environment and Its Biomarkers.

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide, and the identification of biomarkers can improve early detection and personalized treatment. In this study, RNA-seq data and gene chip data from TCGA and GEO were used to explore potential biomarkers for CRC. The SMOTE method was used to address class imbalance, and four feature selection algorithms (MCFS, Borota, mRMR, and LightGBM) were used to select genes from the gene expression matrix. Four machine learning algorithms (SVM, XGBoost, RF, and kNN) were then employed to obtain the optimal number of genes for model construction. Through interpretable machine learning (IML), co-predictive networks were generated to identify rules and uncover underlying relationships among the selected genes. Survival analysis revealed that INHBA, FNBP1, PDE9A, HIST1H2BG, and CADM3 were significantly correlated with prognosis in CRC patients. In addition, the CIBERSORT algorithm was used to investigate the proportion of immune cells in CRC tissues, and gene mutation rates for the five selected biomarkers were explored. The biomarkers identified in this study have significant implications for the development of personalized therapies and could ultimately lead to improved clinical outcomes for CRC patients.

Clinical Impact of Exosomes in Colorectal Cancer Metastasis.

Cancer is a complex deadly disease that has caused a global health crisis in recent epochs. Colorectal cancer (CRC) is the third most common malignant gastrointestinal disease. It has led to high mortality due to early diagnostic failure. Extracellular vesicles (EVs) come with promising solutions for CRC. Exosomes (a subpopulation of EVs) play a vital role as signaling molecules in CRC tumor microenvironment. It is secreted from all active cells. Exosome-based molecular transport (DNA, RNA, proteins, lipids, etc.) transforms the recipient cell's nature. In CRC, tumor cell-derived exosomes (TEXs) regulate multiple events of CRC development and progression such as immunogenic suppression, angiogenesis, epithelial-mesenchymal transitions (EMT), physical changes in the extracellular matrix (ECM), and metastasis. Biofluid-circulated tumor-derived exosomes (TEXs) are a potential tool for CRC liquid biopsy. Exosome-based colorectal cancer detection creates a great impact in CRC biomarker research. The exosome-associated CRC theranostics approach is a state-of-the-art method. In this review, we address the CRC and exosomes complex associated with cancer development and progression, the impact of exosomes on CRC screening (diagnostic and prognostic biomarkers), and also highlight several exosomes with CRC clinical trials, as well as future directions of exosome-based CRC research. Hopefully, it will encourage several researchers to develop a potential exosome-based theranostic tool to fight CRC.