Hyaluronan driven by epithelial aPKC deficiency remodels the microenvironment and creates a vulnerability in mesenchymal colorectal cancer

Research progress of CD73-adenosine signaling regulating hepatocellular carcinoma through tumor microenvironment

Adenosine signaling pathway is a kind of signal regulation hub widely existing in human body, which is involved in a series of physiological processes such as energy supply of body cells. CD73 is a highly concerned signaling protein in purine adenosine pathway, and its role in tumor development and prognosis has been paid more and more attention in recent years, especially in hepatocellular carcinoma (HCC). In this paper, the specific mechanism by which CD73-adenosine signaling regulates tumor microenvironment (TME) of liver cancer tumors was analyzed in detail, highlighting the importance of this pathway as a therapeutic target to combat tumor immunosuppression and enhance the anti-tumor immune response to prevent and treat hepatocellular carcinoma (HCC). In addition, a variety of current targeted therapeutic strategies for adenosine metabolic pathways are summarized, including the development of new drugs in the stage of preclinical research and clinical trials, and the mechanism of action, implementation possibility, and clinical effects of these therapies are discussed. By summarizing the latest scientific research results, in this review, we attempt to paint a panorama of the mechanism of adenosine action in tumor immunotherapy, with the aim to provide a solid theoretical basis and practical guidance for subsequent research and clinical application, ultimately promoting the development of more accurate and efficient tumor immunotherapy.

Tissue-resident memory CD8 T cell diversity is spatiotemporally imprinted

Tissue-resident memory CD8 T (TRM) cells provide protection from infection at barrier sites. In the small intestine, TRM cells are found in at least two distinct subpopulations: one with higher expression of effector molecules and another with greater memory potential1. However, the origins of this diversity remain unknown. Here we proposed that distinct tissue niches drive the phenotypic heterogeneity of TRM cells. To test this, we leveraged spatial transcriptomics of human samples, a mouse model of acute systemic viral infection and a newly established strategy for pooled optically encoded gene perturbations to profile the locations, interactions and transcriptomes of pathogen-specific TRM cell differentiation at single-transcript resolution. We developed computational approaches to capture cellular locations along three anatomical axes of the small intestine and to visualize the spatiotemporal distribution of cell types and gene expression. Our study reveals that the regionalized signalling of the intestinal architecture supports two distinct TRM cell states: differentiated TRM cells and progenitor-like TRM cells, located in the upper villus and lower villus, respectively. This diversity is mediated by distinct ligand-receptor activities, cytokine gradients and specialized cellular contacts. Blocking TGFβ or CXCL9 and CXCL10 sensing by antigen-specific CD8 T cells revealed a model consistent with anatomically delineated, early fate specification. Ultimately, our framework for the study of tissue immune networks reveals that T cell location and functional state are fundamentally intertwined.

Predicting immunotherapy prognosis and targeted therapy sensitivity of colon cancer based on a CAF-related molecular signature

The role of cancer-associated fibroblasts (CAFs) in modulating the tumor microenvironment (TME) is gaining attention, yet their impact on prognosis and therapeutic response in colon cancer remains unclear. Here, we identified genes associated with CAF infiltration via weighted gene co-expression network analysis (WGCNA) utilizing data from The Cancer Genome Atlas (TCGA) and GSE39582 cohorts. Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) regression analyses were used to construct CAF molecular signatures (CAFscore). Patients were categorized into high and low CAFscore groups to analyze clinicopathological traits, somatic mutations, immune evasion, and treatment responses. In this study, a total of 244 genes were correlated with CAF infiltration, with 11 linked to overall survival. Notably, FSTL3, CRIP2, and SLC2A3 were selected for the CAFscore. A higher CAFscore was associated with poorer prognoses, increased malignancy, and therapeutic resistance, particularly among patients with high tumor mutation burden and microsatellite instability. Furthermore, elevated FSTL3 expression was associated with reduced CD8+ T cell infiltration, indicating a suppressive TME. Mechanistically, CAFs may promote immune evasion via NAMPT ligand-receptor interactions based on single-cell RNA sequencing data. Thus, the CAFscore is crucial for personalizing treatment strategies and identifying patients who require more aggressive management.

Advancing biliary tract malignancy treatment: emerging frontiers in cell-based therapies

Biliary tract malignancies, including intrahepatic cholangiocarcinoma, extrahepatic cholangiocarcinoma, and gallbladder cancer, represent a group of aggressive cancers with poor prognosis due to late-stage diagnosis, limited treatment options, and resistance to conventional therapies like chemotherapy and radiotherapy. These challenges emphasize the urgent need for innovative therapeutic approaches. In recent years, cell-based therapies have emerged as a promising avenue, offering potential solutions through immune modulation, genetic engineering, and targeted intervention in the tumor microenvironment. This Mini-review provides an overview of current advancements in cell-based therapies for biliary malignancies, encompassing immune cell-based strategies such as CAR-T cells, NK cells, dendritic cell vaccines, and tumor-infiltrating lymphocytes. We also examine strategies to overcome the immunosuppressive tumor microenvironment and discuss the integration of cell therapies into multimodal treatment regimens. By synthesizing preclinical and clinical findings, this review highlights key insights and future directions, aiming to assist researchers and clinicians in translating these approaches into effective treatments. The transformative potential of cell-based therapies discussed here makes this review a valuable resource for advancing biliary malignancy research and clinical applications.

Mouse colorectal cancer organoids: Lessons from syngeneic and orthotopic transplantation systems

Colorectal cancer (CRC) organoids provide more accurate and tissue-relevant models compared to conventional two-dimensional cultured cell cultures. Mouse CRC organoids, in particular, offer unique advantages over their human counterparts, as they can be transplanted into immunocompetent mice. These syngeneic transplantation models create a robust system for studying cancer biology in the immunocompetent tumor microenvironment (TME). This article discusses the development and applications of these organoid systems, emphasizing their capacity to faithfully recapitulate in vivo tumor progression, metastasis, and the immune landscape.

Metabolic Singularities in Microsatellite-Stable Colorectal Cancer: Identifying Key Players in Immunosuppression to Improve the Immunotherapy Response

Although immune checkpoint inhibitor (ICI) therapy is currently the standard of care in microsatellite-unstable (MSI) metastatic colorectal cancer (CRC), ICI therapy, alone or in combination with other therapies, is not a treatment approach in microsatellite-stable (MSS) CRC, which is present in 95% of patients. In this review, we focus on metabolic singularities-at the transcriptomic (either bulk or single cell), proteomic, and post-translational modification levels-that induce immunosuppression in cancer and specifically in MSS CRC. First, we evaluate the current efficacy of ICIs in limited and metastatic disease in MSS CRC. Second, we discuss the latest findings on the potential biomarkers for evaluating ICI efficacy in MSS CRC using strict REMARK criteria. Third, we review the current evidence on metabolic patterns in CRC tumors and immune cell metabolism to advance our understanding of metabolic crosstalk and to pave the way for the development of combination strategies to enhance ICI efficacy.

Synergistic Anticancer Strategy Targeting ECM Stiffness: Integration of Matrix Softening and Mechanical Signal Transduction Blockade in Primary Liver Cancers

The development of primary liver cancer (hepatocellular carcinoma [HCC] and intrahepatic cholangiocarcinoma [ICC]) is linked to its physical microenvironment, particularly extracellular matrix (ECM) stiffness. Potential anticancer strategies targeting ECM stiffness include prevention/reversal of the stiffening process and disruption of the response of cancer cells to mechanical signals from ECM. However, each strategy has limitations. Therefore, the authors propose integrating them to maximize their strengths. Compared with HCC, ICC has a stiffer ECM and a worse prognosis. Therefore, ICC is selected to investigate mechanisms underlying the influence of ECM stiffness on cancer progression and application of the integrated anticancer strategy targeting ECM stiffness. In summary, immunofluorescence results for 181 primary liver cancer tissue chips (ICC, n = 91; HCC, n = 90) and analysis of TCGA mRNA-sequencing demonstrate that ECM stiffness can affect phenotypes of primary liver cancers. The YAP1/ABHD11-AS1/STAU2/ZYX/p-YAP1 pathway is a useful entry point for exploration of specific mechanisms of mechanical signal conduction from the ECM in ICC cells and their impact on cancer progression. Moreover, a synergistic anticancer strategy targeting ECM stiffness (ICCM@NPs + siABHD11-AS1@BAPN) is constructed by integrating ECM softening and blocking intracellular mechanical signal transduction in ICC and can provide insights for the treatment of cancers characterized by stiff ECM.

New Potent Inhibitor of Transforming Growth Factor-Beta (TGFβ) Signaling that is Efficacious against Microsatellite Stable Colorectal Cancer Metastasis in Combination with Immune Checkpoint Therapy in Mice

Blockade of the TGFβ signaling pathway has emerged from preclinical studies as a potential treatment to enhance the efficacy of immune checkpoint inhibition in advanced colorectal cancer (CRC) and several other types of cancer. However, clinical translation of first-generation inhibitors has shown little success. Here, we report the synthesis and characterization of HYL001, a potent inhibitor of TGFβ receptor 1 (ALK5), that is approximately 9 times more efficacious than the structurally related compound galunisertib, while maintaining a favorable safety profile. HYL001 in combination with immune checkpoint blockade (anti-PD1) eradicates liver metastases generated in mice by microsatellite stable, aggressive colorectal cancer tumors at doses where galunisertib is ineffective.

Hyaluronan Tetrasaccharides Penetrate into the Skin by Passive Diffusion and Contribute to Skin Health

Hyaluronan (HA) is a commonly used material in cosmetics and pharmaceuticals because of its various pharmacological activities. However, because of its large molecular weight, HA penetrates the skin very poorly and most of it remains on the skin surface. Thus, topically applied HA could not be expected to function biologically in the skin. However, we have confirmed that HA tetrasaccharides (HA4), which is the smallest unit of HA, penetrate into the skin by passive diffusion and affect epidermal metabolism. Topical treatment of HA4 rescues the epidermal damage caused by long-term UVA irradiation. Furthermore, various biological functions of HA4 to maintain healthy skin was observed in cell culture studies. This review describes the skin permeability of HA4 and how it contributes to healthy skin.

Dynamics of the immune microenvironment and immune cell PANoptosis in colorectal cancer: recent advances and insights

Colorectal cancer (CRC) is one of the most significant oncological threats to human health globally. Patients often exhibit a high propensity for tumor recurrence and metastasis post-surgery, resulting in suboptimal prognoses. One of the underlying reasons for the metastatic potential of CRC is the sustained abnormal state of the tumor immune microenvironment, particularly characterized by the atypical death of critical immune cells. In recent years, a novel concept of cell death known as PANoptosis has emerged. This form of cell death is regulated by the PANoptosome complex and encompasses key features of apoptosis, pyroptosis, and necroptosis, yet cannot be entirely substituted by any of these processes alone. Due to its widespread occurrence and complex mechanisms, PANoptosis has been increasingly reported in various malignancies, enhancing our understanding of its pathological mechanisms, particularly in the context of CRC. However, the characteristics of immune cell PANoptosis within the CRC immune microenvironment have not been thoroughly elucidated. In this review, we focus on the impact of CRC progression on various immune cell types and summarize the distinctive features of immune cell PANoptosis. Furthermore, we highlight the future research trends and challenges associated with the mechanisms of immune cell PANoptosis in CRC.

Immune dynamics shaping pre-metastatic and metastatic niches in liver metastases: from molecular mechanisms to therapeutic strategies

Liver metastases are commonly detected in the advanced stages of various malignant tumors, representing a significant clinical challenge. Throughout the process of liver metastases formation, immune cells play a pivotal role, particularly in the pre-metastatic and metastatic niches within the liver. Immune cells establish extensive and intricate interactions with tumor cells and other components in the liver, collectively promoting and sustaining the growth of liver metastases. Despite the limited efficacy of existing therapeutic modalities against some advanced liver metastases, novel immune-based treatment approaches are continuously being explored and validated. Building on the systematic elucidation of the immunosuppressive characteristics of liver metastases, we explored the potential of novel immunotherapies applicable to patients with liver metastases from multiple dimensions.

Targeting extracellular matrix interaction in gastrointestinal cancer: Immune modulation, metabolic reprogramming, and therapeutic strategies

The extracellular matrix (ECM) is a major constituent of the tumor microenvironment, acting as a mediator that supports the progression of gastrointestinal (GI) cancers, particularly in mesenchymal subtypes. Beyond providing structural support, the ECM actively shapes the tumor microenvironment (TME) through complex biochemical and biomechanical remodeling. Dysregulation of ECM composition and signaling is closely linked to increased cancer aggressiveness, poor prognosis, and resistance to therapy. ECM components, such as collagen, fibronectin, laminin, and periostin, influence tumor growth, metastasis, immune modulation, and metabolic reprogramming by interacting with tumor cells, immune cells, and cancer-associated fibroblasts. In this review, we highlight the heterogeneous nature of the ECM and the dualistic roles of its components across GI cancers, with a focus on their contributions to immune evasion and metabolic remodeling via intercellular interactions. Additionally, we explore therapeutic strategies targeting ECM remodeling and ECM-centered interactions, emphasizing their potential in enhancing existing anti-tumor therapies.

Protocol to characterize mouse intestinal epithelial cell lineage using Opal multiplex immunofluorescence

Applying Opal multiplex immunofluorescence (OMI) to characterize intestinal tissues of genetically engineered mouse models provides an excellent tool for studying complex processes. However, detecting appropriate signals from multiple target molecules is challenging. Here, we present a protocol to characterize mouse intestinal epithelial cell lineage using OMI. We describe steps for processing small intestine and colonic mouse tissues and designing and optimizing panels for OMI in mouse intestinal tissues. We then detail procedures for performing a quantitative evaluation of acquired images. For complete details on the use and execution of this protocol, please refer to Kinoshita et al.1.

Role of Hyaluronic acid and its chemical derivatives in immunity during homeostasis, cancer and tissue regeneration

Over the last few decades, scientists have recognized the critical role that various components of the extracellular matrix (ECM) play in maintaining homeostatic immunity. Besides, dysregulation in the synthesis or degradation levels of these components directly impacts the mechanisms of immune response during tissue injury caused by tumor processes or the regeneration of the tissue itself in the event of damage. ECM is a complex network of protein compounds, proteoglycans and glycosaminoglycans (GAGs). Hyaluronic acid (HA) is one of the major GAGs of this network, whose metabolism is strictly physiologically regulated and quickly altered in injury processes, affecting the behavior of different cells, from stem cells to differentiated immune cells. In this revision we discuss how the native or chemically modified HA interacts with its specific receptors and modulates intra and intercellular communication of immune cells, focusing on cancer and tissue regeneration conditions.

Calycosin inhibits the proliferation and metastasis of renal cell carcinoma through the MAZ/HAS2 signaling pathway

Calycosin (Caly), a flavonoid compound, demonstrates a variety of beneficial properties. However, the specific mechanisms behind Caly's anticancer effects remain largely unexplored. Network pharmacology was used to explore the potential targets of Caly in renal cancer. Additionally, RNA-seq sequencing was used to detect changes in genes in renal cancer cells after Caly treatment. Validation was carried out through quantitative reverse transcription-PCR and Western blot analysis. The luciferase reporter assay was applied to pinpoint the interaction site between MAZ and HAS2. Furthermore, the immunoprecipitation assay was utilized to examine the ubiquitination and degradation of MAZ. In vivo experiments using cell line-derived xenograft mouse models were performed to assess Calycosin's impact on cancer growth. Network pharmacology research suggests Caly plays a role in promoting apoptosis and inhibiting cell adhesion in renal cancer. In vitro, Caly has been observed to suppress proliferation, colony formation, and metastasis of renal cancer cells while also triggering apoptosis. Additionally, it appears to diminish hyaluronic acid synthesis by downregulating HAS2 expression. MAZ is identified as a transcriptional regulator of HAS2 expression. Calycosin further facilitates the degradation of MAZ via the ubiquitin-proteasome pathway. Notably, Caly demonstrates efficacy in reducing the growth of renal cell carcinoma xenograft tumors in vivo. Our findings indicate that Caly suppresses the proliferation, metastasis, and progression of renal cell carcinoma through its action on the MAZ/HAS2 signaling pathway. Thus, Caly represents a promising therapeutic candidate for the treatment of renal cell carcinoma.

Mechanisms of metastatic colorectal cancer

Despite extensive research and improvements in understanding colorectal cancer (CRC), its metastatic form continues to pose a substantial challenge, primarily owing to limited therapeutic options and a poor prognosis. This Review addresses the emerging focus on metastatic CRC (mCRC), which has historically been under-studied compared with primary CRC despite its lethality. We delve into two crucial aspects: the molecular and cellular determinants facilitating CRC metastasis and the principles guiding the evolution of metastatic disease. Initially, we examine the genetic alterations integral to CRC metastasis, connecting them to clinically marked characteristics of advanced CRC. Subsequently, we scrutinize the role of cellular heterogeneity and plasticity in metastatic spread and therapy resistance. Finally, we explore how the tumour microenvironment influences metastatic disease, emphasizing the effect of stromal gene programmes and the immune context. The ongoing research in these fields holds immense importance, as its future implications are projected to revolutionize the treatment of patients with mCRC, hopefully offering a promising outlook for their survival.

Epithelial aPKC deficiency leads to stem cell loss preceding metaplasia in colorectal cancer initiation

The early mechanisms of spontaneous tumor initiation that precede malignancy are largely unknown. We show that reduced aPKC levels correlate with stem cell loss and the induction of revival and metaplastic programs in serrated- and conventional-initiated premalignant lesions, which is perpetuated in colorectal cancers (CRCs). Acute inactivation of PKCλ/ι in vivo and in mouse organoids is sufficient to stimulate JNK in non-transformed intestinal epithelial cells (IECs), which promotes cell death and the rapid loss of the intestinal stem cells (ISCs), including those that are LGR5+. This is followed by the accumulation of revival stem cells (RSCs) at the bottom of the crypt and fetal-metaplastic cells (FMCs) at the top, creating two spatiotemporally distinct cell populations that depend on JNK-induced AP-1 and YAP. These cell lineage changes are maintained during cancer initiation and progression and determine the aggressive phenotype of human CRC, irrespective of their serrated or conventional origin.

Screening Splice-Switching Antisense Oligonucleotides in Pancreas-Cancer Organoids

Aberrant alternative splicing is emerging as a cancer hallmark and a potential therapeutic target. It is the result of dysregulated or mutated splicing factors, or genetic alterations in splicing-regulatory cis-elements. Targeting individual altered splicing events associated with cancer-cell dependencies is a potential therapeutic strategy, but several technical limitations need to be addressed. Patient-derived organoids are a promising platform to recapitulate key aspects of disease states, and to facilitate drug development for precision medicine. Here, we report an efficient antisense-oligonucleotide (ASO) lipofection method to systematically evaluate and screen individual splicing events as therapeutic targets in pancreatic ductal adenocarcinoma organoids. This optimized delivery method allows fast and efficient screening of ASOs, e.g., those that reverse oncogenic alternative splicing. In combination with advances in chemical modifications of oligonucleotides and ASO-delivery strategies, this method has the potential to accelerate the discovery of antitumor ASO drugs that target pathological alternative splicing.

HAS2 facilitates glioma cell malignancy and suppresses ferroptosis in an FZD7-dependent manner

Glioma is the most common malignant tumor in the central nervous system, and it is crucial to uncover the factors that influence prognosis. In this study, we utilized Mfuzz to identify a gene set that showed a negative correlation with overall survival in patients with glioma. Gene Ontology (GO) enrichment analyses were then undertaken to gain insights into the functional characteristics and pathways associated with these genes. The expression distribution of Hyaluronan Synthase 2 (HAS2) was explored across multiple datasets, revealing its expression patterns. In vitro and in vivo experiments were carried out through gene knockdown and overexpression to validate the functionality of HAS2. Potential upstream transcription factors of HAS2 were predicted using transcriptional regulatory databases, and these predictions were experimentally validated using ChIP-PCR and dual-luciferase reporter gene assays. The results showed that elevated expression of HAS2 in glioma indicates poor prognosis. HAS2 was found to play a role in activating an antiferroptosis pathway in glioma cells. Inhibiting HAS2 significantly increased cellular sensitivity to ferroptosis-inducing agents. Finally, we determined that the oncogenic effect of HAS2 is mediated by the key receptor of the WNT pathway, FZD7.

Mitochondria-Targeted Nanoadjuvants Induced Multi-Functional Immune-Microenvironment Remodeling to Sensitize Tumor Radio-Immunotherapy

It is newly revealed that collagen works as a physical barrier to tumor immune infiltration, oxygen perfusion, and immune depressor in solid tumors. Meanwhile, after radiotherapy (RT), the programmed death ligand-1 (PD-L1) overexpression and transforming growth factor-β (TGF-β) excessive secretion would accelerate DNA damage repair and trigger T cell exclusion to limit RT efficacy. However, existing drugs or nanoparticles can hardly address these obstacles of highly effective RT simultaneously, effectively, and easily. In this study, it is revealed that inducing mitochondria dysfunction by using oxidative phosphorylation inhibitors like Lonidamine (LND) can serve as a highly effective multi-immune pathway regulation strategy through PD-L1, collagen, and TGF-β co-depression. Then, IR-LND is prepared by combining the mitochondria-targeted molecule IR-68 with LND, which then is loaded with liposomes (Lip) to create IR-LND@Lip nanoadjuvants. By doing this, IR-LND@Lip more effectively sensitizes RT by generating more DNA damage and transforming cold tumors into hot ones through immune activation by PD-L1, collagen, and TGF-β co-inhibition. In conclusion, the combined treatment of RT and IR-LND@Lip ultimately almost completely suppressed the growth of bladder tumors and breast tumors.

Correlation analysis of interstitial maturity and prognosis of colorectal cancer: Meta-analysis

BACKGROUND

To investigate the relationship between interstitial maturity and prognosis of colorectal cancer.

AIM

To examine the correlation between interstitial maturity and the prognosis of colorectal cancer.

METHODS

The paper database PubMed, EMBASE, Cochranelibrary, Springerlink, CNKI, and Wanfang database were searched until December 2023. "tumor stroma maturity" "desmoplastic stroma reaction" "desmoplastic reaction" "stroma reaction" "degree of stroma reaction "" stroma classification" "stroma density" "colorectal cancer" "colon cancer" "rectal cancer" "prognosis" were searched for the search terms. Two system assessors independently screened the literature quality according to the inclusion exclusion criteria, Quality evaluation and data extraction were performed for the included literatures, and meta-analysis was performed for randomized control trials included at using Review Manager 5.2 software.

RESULTS

Finally, data of 9849 patients with colorectal cancer from 19 cosets in 15 literatures were included, including 4339 patients with mature type (control group), 3048 patients with intermediate type (intermediate group) and 2456 patients with immature type (immature group). The results of meta-analysis showed: Relapse-free survival [hazard ratio (HR) = 2.66, 95% confidence interval (CI): 2.30-3.08; P < 0.00001], disease-free survival (HR = 3.68, 95%CI: 2.33-5.81; P < 0.00001) and overall survival (HR = 1.70, 95%CI: 1.53-1.87; P < 0.00001) were significantly lower than those in mature group (control group); relapse-free survival (HR = 1.36, 95%CI: 1.17-1.59; P < 0.0001) and disease-free survival rate (HR = 1.85, 95%CI: 1.53-2.24; P < 0.0001) was significantly lower than the mature group (control group).

CONCLUSION

There is the correlation between tumor interstitial maturity and survival prognosis of colorectal cancer, and different degrees of tumor interstitial maturity have a certain impact on the quality of life of colorectal cancer patients.

Clinical Challenges of Consensus Molecular Subtype CMS4 Colon Cancer in the Era of Precision Medicine

Over the past decade, our understanding of the diversity of colorectal cancer has expanded significantly, raising hopes of tailoring treatments more precisely for individual patients. A key achievement in this direction was the establishment of the consensus molecular classification, particularly identifying the challenging consensus molecular subtype (CMS) CMS4 associated with poor prognosis. Because of its aggressive nature, extensive research is dedicated to the CMS4 subgroup. Recent years have unveiled molecular and microenvironmental features at the tissue level specific to CMS4 colorectal cancer. This has paved the way for mechanistic studies and the development of preclinical models. Simultaneously, efforts have been made to easily identify patients with CMS4 colorectal cancer. Reassessing clinical trial results through the CMS classification lens has improved our understanding of the therapeutic challenges linked to this subtype. Exploration of the biology of CMS4 colorectal cancer is yielding potential biomarkers and novel treatment approaches. This overview aims to provide insights into the clinico-biological characteristics of the CMS4 subgroup, the molecular pathways driving this subtype, and available diagnostic options. We also emphasize the therapeutic challenges associated with this subtype, offering potential explanations. Finally, we summarize the current tailored treatments for CMS4 colorectal cancer emerging from fundamental and preclinical studies.

Epithelial-immune cell crosstalk for intestinal barrier homeostasis

The intestinal barrier is mainly formed by a monolayer of epithelial cells, which forms a physical barrier to protect the gut tissues from external insults and provides a microenvironment for commensal bacteria to colonize while ensuring immune tolerance. Moreover, various immune cells are known to significantly contribute to intestinal barrier function by either directly interacting with epithelial cells or by producing immune mediators. Fulfilling this function of the gut barrier for mucosal homeostasis requires not only the intrinsic regulation of intestinal epithelial cells (IECs) but also constant communication with immune cells and gut microbes. The reciprocal interactions between IECs and immune cells modulate mucosal barrier integrity. Dysregulation of barrier function could lead to dysbiosis, inflammation, and tumorigenesis. In this overview, we provide an update on the characteristics and functions of IECs, and how they integrate their functions with tissue immune cells and gut microbiota to establish gut homeostasis.

Discovery of non-genomic drivers of YAP signaling modulating the cell plasticity in CRC tumor lines

In normal intestines, a fetal/regenerative/revival cell state can be induced upon inflammation. This plasticity in cell fate is also one of the current topics in human colorectal cancer (CRC). To dissect the underlying mechanisms, we generated human CRC organoids with naturally selected genetic mutation profiles and exposed them to two different conditions by modulating the extracellular matrix (ECM). Among tested mutation profiles, a fetal/regenerative/revival state was induced following YAP activation via a collagen type I-enriched microenvironment. Mechanistically, YAP transcription was promoted by activating AP-1 and TEAD-dependent transcription and suppressing intestinal lineage-determining transcription via mechanotransduction. The phenotypic conversion was also involved in chemoresistance, which could be potentially resolved by targeting the underlying YAP regulatory elements, a potential target of CRC treatment.

Serrated colorectal cancer: preclinical models and molecular pathways

Serrated lesions are histologically heterogeneous, and detection can be challenging as these lesions have subtle features that may be missed by endoscopy. Furthermore, while approximately 30% of colorectal cancers (CRCs) arise from serrated lesions, only 8-10% of invasive serrated CRCs exhibit serrated morphology at presentation, suggesting potential loss of apparent characteristics with increased malignancy. Thus, understanding the genetic basis driving serrated CRC initiation and progression is critical to improve diagnosis and identify therapeutic biomarkers and targets to guide disease management. This review discusses the preclinical models of serrated CRCs reported to date and how these systems have been used to provide mechanistic insights into tumor initiation, progression, and novel treatment targets.

Cell polarity changes in cancer initiation and progression

Cell polarity, which consists of the morphological, structural, and functional organization of cells along a defined axis, is a feature of healthy cells and tissues. In contrast, abnormal polarity is a hallmark of cancer cells. At the molecular level, key evolutionarily conserved proteins that control polarity establishment and maintenance in various contexts are frequently altered in cancer, but the relevance of these molecular alterations in the oncogenic processes is not always clear. Here, we summarize the recent findings, shedding new light on the involvement of polarity players in cancer development, and discuss the possibility of harnessing cell polarity changes to better predict, diagnose, and cure cancers.

Enhanced SREBP2-driven cholesterol biosynthesis by PKCλ/ι deficiency in intestinal epithelial cells promotes aggressive serrated tumorigenesis

The metabolic and signaling pathways regulating aggressive mesenchymal colorectal cancer (CRC) initiation and progression through the serrated route are largely unknown. Although relatively well characterized as BRAF mutant cancers, their poor response to current targeted therapy, difficult preneoplastic detection, and challenging endoscopic resection make the identification of their metabolic requirements a priority. Here, we demonstrate that the phosphorylation of SCAP by the atypical PKC (aPKC), PKCλ/ι promotes its degradation and inhibits the processing and activation of SREBP2, the master regulator of cholesterol biosynthesis. We show that the upregulation of SREBP2 and cholesterol by reduced aPKC levels is essential for controlling metaplasia and generating the most aggressive cell subpopulation in serrated tumors in mice and humans. Since these alterations are also detected prior to neoplastic transformation, together with the sensitivity of these tumors to cholesterol metabolism inhibitors, our data indicate that targeting cholesterol biosynthesis is a potential mechanism for serrated chemoprevention.

THBS1-producing tumor-infiltrating monocyte-like cells contribute to immunosuppression and metastasis in colorectal cancer

Mesenchymal activation, characterized by dense stromal infiltration of immune and mesenchymal cells, fuels the aggressiveness of colorectal cancers (CRC), driving progression and metastasis. Targetable molecules in the tumor microenvironment (TME) need to be identified to improve the outcome in CRC patients with this aggressive phenotype. This study reports a positive link between high thrombospondin-1 (THBS1) expression and mesenchymal characteristics, immunosuppression, and unfavorable CRC prognosis. Bone marrow-derived monocyte-like cells recruited by CXCL12 are the primary source of THBS1, which contributes to the development of metastasis by inducing cytotoxic T-cell exhaustion and impairing vascularization. Furthermore, in orthotopically generated CRC models in male mice, THBS1 loss in the TME renders tumors partially sensitive to immune checkpoint inhibitors and anti-cancer drugs. Our study establishes THBS1 as a potential biomarker for identifying mesenchymal CRC and as a critical suppressor of antitumor immunity that contributes to the progression of this malignancy with a poor prognosis.

Sessile serrated lesions with dysplasia: is it possible to nip them in the bud?

The serrated neoplasia pathway constitutes an "alternative route" to colorectal cancer (CRC), and sessile serrated lesions with dysplasia (SSLDs) are an intermediate step between sessile serrated lesions (SSLs) and invasive CRC in this pathway. While SSLs show indolent growth before becoming dysplastic (> 10-15 years), SSLDs are considered to rapidly progress to either immunogenic microsatellite instable-high (MSI-H) CRC (presumably 75% of cases) or mesenchymal microsatellite stable (MSS) CRC. Their flat shapes and the relatively short window of this intermediate state make it difficult to detect and diagnose SSLDs; thus, these lesions are potent precursors of post-colonoscopy/interval cancers. Confusing terminology and the lack of longitudinal observation data of serrated polyps have hampered the accumulation of knowledge about SSLDs; however, a growing body of evidence has started to clarify their characteristics and biology. Together with recent efforts to incorporate terminology, histological studies of SSLDs have identified distinct dysplastic patterns and revealed alterations in the tumor microenvironment (TME). Molecular studies at the single-cell level have identified distinct gene alterations in both the epithelium and the TME. Mouse serrated tumor models have demonstrated the importance of TME in disease progression. Advances in colonoscopy provide clues to distinguish pre-malignant from non-malignant-SSLs. Recent progress in all aspects of the field has enhanced our understanding of the biology of SSLDs. The aim of this review article was to assess the current knowledge of SSLDs and highlight their clinical implications.

Whole-mount staining of mouse colorectal cancer organoids and fibroblast-organoid co-cultures

Imaging organoid culture provides an excellent tool for studying complex diseases such as cancer. However, retaining the morphology of intact organoids for immunolabeling has been challenging. Here, we describe a protocol for immunofluorescence staining in intact colorectal cancer organoids derived from mice. We also describe additional steps for co-culture with mouse fibroblasts to enable the study of interactions with other cellular components of the tissue microenvironment. For complete details on the use and execution of this protocol, please refer to Martinez-Ordoñez et al. (2023).1.