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Fusobacterium nucleatum (F. nucleatum) promotes intestinal tumor growth and its relative abundance varies greatly among patients with CRC, suggesting the presence of unknown, individual-specific effectors in F. nucleatum-dependent carcinogenesis. Here, we identify that F. nucleatum is enriched preferentially in KRAS p.G12D mutant CRC tumor tissues and contributes to colorectal tumorigenesis in Villin-Cre/Kras G12D+/- mice. Additionally, Parabacteroides distasonis (P. distasonis) competes with F. nucleatum in the G12D mouse model and human CRC tissues with the KRAS mutation. Orally gavaged P. distasonis in mice alleviates the F. nucleatum-dependent CRC progression. F. nucleatum invades intestinal epithelial cells and binds to DHX15, a protein of RNA helicase family expressed on CRC tumor cells, mechanistically involving ERK/STAT3 signaling. Knock out of Dhx15 in Villin-Cre/Kras G12D+/- mice attenuates the CRC phenotype. These findings reveal that the oncogenic effect of F. nucleatum depends on somatic genetics and gut microbial ecology and indicate that personalized modulation of the gut microbiota may provide a more targeted strategy for CRC treatment., (© 2024. The Author(s).)

Background: One reason patients with cancer cannot benefit from immunotherapy is the lack of immune cell infiltration in tumor tissues. Cancer-associated fibroblasts (CAFs) are emerging as central players in immune regulation that shapes tumor microenvironment (TME). Earlier we reported that integrin α5 was enriched in CAFs in colorectal cancer (CRC), however, its role in TME and cancer immunotherapy remains unclear. Here, we aimed to investigate the role for integrin α5 in fibroblasts in modulating antitumor immunity and therapeutic efficacy combined with checkpoint blockade in CRC., Methods: We analyzed the CRC single-cell RNA sequencing (scRNA-seq) database to define the expression of ITGA5 in CRC tumor stroma. Experimentally, we carried out in vivo mouse tumor xenograft models to confirm the targeting efficacy of combined α5β1 inhibition and anti-Programmed death ligand 1 (PD-L1) blockade and in vitro cell-co-culture assay to investigate the role of α5 in fibroblasts in affecting T-cell activity. Clinically, we analyzed the association between α5 expression and infiltrating T cells and evaluated their correlation with patient survival and immunotherapy prognosis in CRC., Results: We revealed that ITGA5 was enriched in FAP -CAFs. Both ITGA5 knockout fibroblasts and therapeutic targeting of α5 improved response to anti-PD-L1 treatment in mouse subcutaneous tumor models. Mechanistically, these treatments led to increased tumor-infiltrating CD8 + T cells. Furthermore, we found that α5 in fibroblasts correlated with extracellular matrix (ECM)-related genes and affected ECM deposition in CRC tumor stroma. Both in vivo analysis and in vitro culture and cell killing experiment showed that ECM proteins and α5 expression in fibroblasts influence T-cell infiltration and activity. Clinically, we confirmed that high α5 expression was associated with fewer CD3 + T and CD8 + T cells, and tissues with low α5 and high CD3 + T levels correlated with better patient survival and immunotherapy response in a CRC cohort with 29 patients., Conclusions: Our study identified a role for integrin α5 in fibroblasts in modulating antitumor immunity by affecting ECM deposition and showed therapeutic efficacy for combined α5β1 inhibition and PD-L1 blockade in CRC., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

As with many diseases, tumor formation in colorectal cancer (CRC) is multifactorial and involves immune, environmental factors and various genetics that contribute to disease development. Accumulating evidence suggests that the gut microbiome is linked to the occurrence and development of CRC, and these microorganisms are important for immune maturation. However, a systematic perspective integrating microbial profiling, T cell receptor (TCR) and somatic mutations in humans with CRC is lacking. Here, we report distinct features of the expressed TCRβ repertoires in the peripheral blood of and CRC patients ( n  = 107) and healthy donors ( n  = 30). CRC patients have elevated numbers of large TCRβ clones and they have very low TCR diversity. The metagenomic sequencing data showed that the relative abundance of Fusobacterium nucleatum ( F. nucleatum ), Escherichia coli and Dasheen mosaic virus were elevated consistently in CRC patients ( n  = 97) compared to HC individuals ( n  = 30). The abundance of Faecalibacterium prausnitzii and Roseburia intestinalis was reduced in CRC ( n  = 97) compared to HC ( n  = 30). The correlation between somatic mutations of target genes (16 genes, n  = 79) and TCR clonality and microbial biomarkers in CRC had been investigated. Importantly, we constructed a random forest classifier (contains 15 features) based on microbiome and TCR repertoires, which can be used as a clinical detection method to screen patients for CRC. We also analysis of F. nucleatum -specific TCR repertoire characteristics. Collectively, our large-cohort multi-omics data aimed to identify novel biomarkers to inform clinical decision-making in the detection and diagnosis of CRC, which is of possible etiological and diagnostic significance.

Previous studies have repeatedly investigated the effects of MALAT1 gene rs3200401 and MEG3 gene rs7158663 on cancer risk. However, their results remain conflicting rather than conclusive. Therefore, we here performed a case-control study and a followed meta-analysis to examine their contribution to the risk of lung, colorectal, gastric and liver cancer. 550 lung cancer patients, 787 colorectal cancer patients, 460 gastric cancer patients, 480 liver cancer patients and 800 normal controls were included. The genotyping of rs3200401 and rs7158663 was applied with Sanger sequencing technology. Our case-control study revealed that in Hubei Chinese population, rs3200401 was significantly associated with the risk of gastric cancer but not lung, colorectal, or liver cancer, rs7158663 was significantly associated with the risk of gastric and colorectal cancer but not lung or liver cancer. The followed meta-analysis, combining the data of previous studies and present study, showed that rs3200401 was significantly associated with the risk of gastric and colorectal cancer in the pooled population but not liver cancer in Chinese population, rs7158663 was significantly associated with the risk of lung, colorectal and gastric but not liver cancer in Chinese population. Collectively, MALAT1 gene rs3200401 may be a susceptive factor for the development of colorectal and gastric cancer, and MEG3 gene rs7158663 may be a susceptive factor for the development of lung, colorectal and gastric cancer. However, the findings should be validated in future studies with larger sample sizes of different ethnic populations., Competing Interests: Conflict of interest None of the authors has a financial interest related to this study to disclose., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Given that only a subset of patients with colorectal cancer (CRC) benefit from immune checkpoint therapy, efforts are ongoing to identify markers that predict immunotherapeutic response. Increasing evidence suggests that microbes influence the efficacy of cancer therapies. Fusobacterium nucleatum induces different immune responses in CRC with different microsatellite-instability (MSI) statuses. Here, we investigated the effect of F. nucleatum on anti-PD-L1 therapy in CRC. We found that high F. nucleatum levels correlate with improved therapeutic responses to PD-1 blockade in patients with CRC. Additionally, F. nucleatum enhanced the antitumor effects of PD-L1 blockade on CRC in mice and prolonged survival. Combining F. nucleatum supplementation with immunotherapy rescued the therapeutic effects of PD-L1 blockade. Furthermore, F. nucleatum induced PD-L1 expression by activating STING signaling and increased the accumulation of interferon-gamma (IFN-γ) + CD8 + tumor-infiltrating lymphocytes (TILs) during treatment with PD-L1 blockade, thereby augmenting tumor sensitivity to PD-L1 blockade. Finally, patient-derived organoid models demonstrated that increased F. nucleatum levels correlated with an improved therapeutic response to PD-L1 blockade. These findings suggest that F. nucleatum may modulate immune checkpoint therapy for CRC., (© 2021. The Author(s).)

Emerging research has revealed regulation of colorectal cancer metabolism by bacteria. Fusobacterium nucleatum ( Fn ) plays a crucial role in the development of colorectal cancer, however, whether Fn infection modifies metabolism in patients with colorectal cancer remains unknown. Here, LC-MS/MS-based lipidomics identified the upregulation of cytochrome P450 monooxygenases, primarily CYP2J2, and their mediated product 12,13-EpOME in patients with colorectal cancer tumors and mouse models, which increased the invasive and migratory ability of colorectal cancer cells in vivo and in vitro by regulating the epithelial-mesenchymal transition (EMT). Metagenomic sequencing indicated a positive correlation between increased levels of fecal Fn and serum 12,13-EpOME in patients with colorectal cancer. High levels of CYP2J2 in tumor tissues also correlated with high Fn levels and worse overall survival in patients with stage III/IV colorectal cancer. Moreover, Fn was found to activate TLR4/AKT signaling, downregulating Keap1 and increasing NRF2 to promote transcription of CYP2J2. Collectively, these data identify that Fn promotes EMT and metastasis in colorectal cancer by activating a TLR4/Keap1/NRF2 axis to increase CYP2J2 and 12,13-EpOME, which could serve as clinical biomarkers and therapeutic targets for Fn -infected patients with colorectal cancer. SIGNIFICANCE: This study uncovers a mechanism by which Fusobacterium nucleatum regulates colorectal cancer metabolism to drive metastasis, suggesting the potential biomarker and therapeutic utility of the CYP2J2/12,13-EpOME axis in Fn -infected patients., (©2021 American Association for Cancer Research.)

The tumorigenesis of colorectal cancer (CRC) is a complicated process, involving interactions between cancer cells and the microenvironment. The role of α5 integrin subunit in CRC remains controversial, and previous studies mainly focused on cancer cells. Herein, we report an important role of α5 in stroma fibroblasts in the tumorigenesis of CRC. The expression of α5 was found to be located in colorectal tumor stroma rather than in epithelia cancer cells. Immunofluorescence colocalization and gene correlation analysis confirmed that α5 was mainly expressed in cancer-associated fibroblasts (CAFs). Moreover, experimental evidence showed that α5 expression was required for the tumor-promoting effect of fibroblast cells. In an in vivo xenograft nude mice model, α5 depletion in fibroblasts dramatically suppressed fibroblast-induced tumor growth. In an in vitro cell coculture assay, α5 depletion or knockdown reduced the ability of fibroblasts to promote cancer cell migration and invasion compared with wild-type fibroblasts; moreover, we observed that the expression and assembly of fibronectin were downregulated after α5 depletion or knockdown in fibroblasts. Analysis of the RNA-Seq data of the Cancer Genome Atlas cohort revealed that high expression of ITGA5 (α5 integrin subunit) was correlated with poor overall survival in colorectal adenocarcinoma, which was further confirmed by immunohistochemistry in an independent cohort of 355 patients. Thus, our study identifies α5 integrin subunit as a novel stroma molecular marker for colorectal adenocarcinoma, offers a fresh insight into colorectal adenocarcinoma progression, and shows that α5 expression in stroma fibroblasts underlies its ability to promote the tumorigenesis of colorectal adenocarcinoma., (© 2019 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.)

Many clustered protocadherin genes (PCDHs) within chromosome 5q31 are frequently down-regulated in colorectal cancer (CRC) due to the hypermethylation of this region, and some of them have been identified as tumor suppressors. However, the association between the expression of the clustered PCDHs and prognosis of CRC patients is still unclear. Here, we identified multiple PCDHs that were significantly down-regulated in CRC by analyzing the RNA-seq data of the Cancer Genome Atlas (TCGA) cohort. Among them, one γ-PCDH subfamily member, PCDHGA7, was found to be associated with overall survival in the patients with wild-type KRAS. Next, we experimentally validated the decrease of PCDHGA7 mRNA and protein levels in tumor tissues of 20 CRC patients by using quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry assay (IHC). To further investigate whether the expression of PCDHGA7 could predict clinical outcomes, an independent cohort of 138 patients, whose tumors carried wild-type KRAS, was enrolled. In-house tissue microarrays (TMAs) were developed to facilitate the protein detection, and prognostic significance was analyzed. The result showed low PCDHGA7 expression was associated with advanced TNM stage, high risk of tumor recurrence and short overall survival. In conclusion, this study demonstrates that PCDHGA7 is down-regulated in CRC, and its expression level is correlated with clinical outcomes in patients with wild-type KRAS. Our finding indicates PCDHGA7 could serve as a potential novel biomarker to predict prognosis by combining certain tumor genotypes in patients of CRC., (Copyright © 2018 Elsevier Inc. All rights reserved.)