IL1R1+ cancer-associated fibroblasts drive tumor development and immunosuppression in colorectal cancer

Identification and validation of immune-related biomarkers and polarization types of macrophages in keloid based on bulk RNA-seq and single-cell RNA-seq analysis

INTRODUCTION

Keloids are a common complication that occurs after injury. The pathogenesis of this disease remains unknown. Therefore, identifying immune-related biomarkers and macrophage polarization types in keloids can provide new insights into their treatment.

METHODS

In this study, keloid-related bulk RNA-seq data (GSE83286, GSE212954, GSE92566, and GSE90051) were obtained from the Gene Expression Omnibus (GEO) database. The datasets GSE83286, GSE212964, and GSE92566 were combined to form a training set, while GSE90051 was utilized as an external validation set. Differentially expressed genes (DEGs) were detected by comparing keloid and normal samples within the training set. Differentially expressed immune-related genes (DIRGs) were then determined by intersecting the DEGs with immune-related genes (IRGs). Based on the protein-protein interaction (PPI) network, the top 40 DIRGs were selected for further analyses. Weighted Gene Co-expression Network Analysis (WGCNA), in conjunction with three machine learning techniques - least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), and random forest (RF) - employed to identify biomarkers. Subsequently, a nomogram model was constructed and validated. Single-cell RNA (scRNA) analysis was used to examine the expression of biomarkers at the cell-type level. Furthermore, since keloid is a chronic inflammatory disease and the abnormal polarization of macrophages is essential for the occurrence of this kind of disease, in this study we also endeavor to elucidate the state of macrophage polarization dysregulation within keloid, with the anticipation of generating novel concepts for the treatment of keloid. Finally, western blot (WB) and immunofluorescence (IF) analyses were carried out to confirm the expression levels of the biomarkers.

RESULTS

A total of 740 DEGs were identified in the training set, comprising 331 up-regulated genes and 409 down-regulated genes. After intersecting with the IRGs, 73 DIRGs were obtained. Subsequently, the top 40 DIRGs were chosen for further analysis. Eventually, two biomarkers, namely BMP1 and IL1R1, were identified through WGCNA and the three machine learning methods. Their expression levels were then verified by single-cell analysis, WB, and IF analysis. Additionally, it was found that the number of M2 macrophages significantly increased, while the number of M1 macrophages decreased in keloids compared to normal samples.

CONCLUSION

BMP1 and IL1R1 might function as novel biomarkers and potential therapeutic targets for keloid treatment. Moreover, upregulating M1 macrophages and downregulating M2 macrophages could represent a promising approach for the treatment of keloids.

Identification of lactylation-associated fibroblast subclusters predicting prognosis and cancer immunotherapy response in colon cancer

BACKGROUND

Lactylation plays an important role in tumor progression. This study aimed to clarify the impact of lactylation on cancer-associated fibroblasts(CAFs).

METHODS

Single-cell and bulk RNA sequence data, along with survival information, were obtained from TCGA and GEO datasets. Significant lactylation-associated genes were acquired by differential analysis and used to construct a prognostic model via Cox and LASSO regression analyses. Next, single-cell analysis, enrichment and pathway analysis, pseudotemporal trajectory and survival analysis were used to identify significant lactylation-associated fibroblast subclusters in colon cancer. IMvigor210 and PRJEB23709 cohorts were applied to assess the response to immunotherapy. In vitro experiments were conducted to explore how lactylation affect fibroblasts.

RESULTS

We established a lactylation-associated prognostic model with 17 risk genes in TCGA and further validated it in GEO datasets. Single-cell analysis revealed the lactylation level of fibroblasts in colon cancer was greater than that in normal tissues. Moreover, five lactylation-associated fibroblast subclusters were identified via the NMF algorithm. Patients with lower scores of FB_2_CALD1, FB_3_TPM4 and FB_4_AHNAK subclusters had better clinical prognosis in colon cancer and were more likely to benefit from immunotherapy. Further experiments demonstrated that lactylation could enhance the proliferation, migration and invasion ability of fibroblasts and up-regulate the expression of COL1A1, which was similar to the effect of colon cancer cells.

CONCLUSION

This study identified key fibroblast subclusters with prognostic value and implied that lactylation might help transform fibroblasts into CAFs in colon cancer for the first time, which provides new paths for understanding the evolution of CAFs and cancer therapeutic strategies.

Clonal Hematopoiesis of Indeterminate Potential as a Predictor of Colorectal Cancer Risk: Insights from the UK Biobank Cohort

BACKGROUND

Clonal hematopoiesis of indeterminate potential (CHIP) has been shown to be associated with the occurrence of solid tumors, but its relationship with colorectal cancer still needs to be studied.

METHODS

We conducted a prospective matched case-control study using data from the UK Biobank, including 5,310 incident colorectal cancer cases and 26,550 controls matched for age, sex, and body mass index.

RESULTS

Analysis of the UK Biobank data revealed that the presence of CHIP was associated with an increased risk of colorectal cancer. The odds ratio (OR) for colorectal cancer in the presence of CHIP was 1.20 (P = 0.006). This association remained significant even after excluding participants with a family history of bowel cancer (multivariate OR, 1.19; P = 0.007). Subgroup analyses demonstrated that CHIP independently increased the risk of colorectal cancer in females (multivariate OR, 1.25; P = 0.018) and in individuals older than 60 years (multivariate OR, 1.17; P = 0.046). Gene-specific analyses revealed that mutations in TET2 and ATM were particularly significant in relation to colorectal cancer risk, with an OR of 1.62 (P = 0.002) for TET2 and 2.98 (P < 0.001) for ATM.

CONCLUSIONS

Our findings indicate that CHIP is associated with an increased risk of colorectal cancer, particularly in individuals more than 60 years of age or in females.

IMPACT

Screening for CHIP in the population may improve the early detection and diagnosis rates of colorectal cancer.

Targeting Cancer-Associated Fibroblasts: Eliminate or Reprogram?

Cancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment (TME). Given their various roles in tumor progression and treatment resistance, CAFs are promising therapeutic targets in cancer. The elimination of tumor-promoting CAFs has been investigated in various animal models to determine whether it effectively suppresses tumor growth. Based on recent evidence, several simple strategies have been proposed to eliminate tumor-promoting CAFs and attenuate these features. In addition, attention has focused on the critical role that CAFs play in the immunosuppressive TME. Therefore, the functional reprogramming of CAFs in combination with immune checkpoint inhibitors has also been investigated as a possible therapeutic approach. However, although potential targets in CAFs have been widely characterized, the plasticity and heterogeneity of CAFs complicate the understanding of their properties and present difficulties for clinical application. Moreover, the identification of tumor-suppressive CAFs highlights the necessity for the development of therapeutic approaches that can distinguish and switch between tumor-promoting and tumor-suppressive CAFs in an appropriate manner. In this review, we introduce the origins and diversity of CAFs, their role in cancer, and current therapeutic strategies aimed at targeting CAFs, including ongoing clinical evaluations.

Regulation of pathologic fibroblast functions in digestive diseases: a role for hypoxia?

The recent uncovering of fibroblast heterogeneity has given great insight into the versatility of the stroma. Among other cellular processes, fibroblasts are now thought to contribute to the coordination of immune responses in a range of chronic inflammatory diseases and cancer. Although the pathologic roles of myofibroblasts, inflammatory fibroblasts, and cancer-associated fibroblasts in disease are reasonably well understood, the mechanisms behind their activation remain to be uncovered. In the gastrointestinal (GI) tract, several interleukins and tumor necrosis factor superfamily members have been identified as possible mediators driving the acquisition of inflammatory and fibrotic properties in fibroblasts. In addition to cytokines, other microenvironmental factors such as nutrient and oxygen availability are likely contributors to this process. In this respect, the phenomenon of low cellular oxygen levels known as hypoxia is common in a plethora of GI diseases. Indeed, the cross talk between hypoxia and inflammation is well-documented, with an abundance of studies suggesting that oxygen-sensing enzymes may have regulatory effects on inflammatory signaling pathways such as NF-κB. However, the impact that this has in GI fibroblasts in the context of chronic diseases has not been fully uncovered. Here we discuss the role of fibroblasts in GI diseases, the mediators that have emerged as regulators of their functions and the potential impact of hypoxia in this process, highlighting areas that require further investigation.

A New Blood-Based Epigenetic Diagnostic Biomarker Test (EpiSwitch®® NST) with High Sensitivity and Positive Predictive Value for Colorectal Cancer and Precancerous Polyps

BACKGROUND/OBJECTIVES

Colorectal cancer (CRC) arises from the epithelial lining of the colon or rectum, often following a progression from benign adenomatous polyps to malignant carcinoma. Screening modalities such as colonoscopy, faecal immunochemical tests (FIT), and FIT-DNA are critical for early detection and prevention, but non-invasive methods lack sensitivity to polyps and early CRC. Chromosome conformations (CCs) are potent epigenetic regulators of gene expression. We have previously developed an epigenetic assay, EpiSwitch®®, that employs an algorithmic-based CCs analysis. Using EpiSwitch®® technology, we have shown the presence of cancer-specific CCs in peripheral blood mononuclear cells (PBMCs) and primary tumours of patients with melanoma and prostate cancer. EpiSwitch®®-based commercial tests are now available to diagnose prostate cancer with 94% accuracy (PSE test) and response to immune checkpoint inhibitors across 14 cancers with 85% accuracy (CiRT test). Methods/Results/Conclusions: Using blood samples collected from n = 171 patients with CRC, n = 44 patients with colorectal polyps and n = 110 patients with a 'clear' colonoscopy we performed whole Genome DNA screening for CCs correlating to CRC diagnosis. Our findings suggest the presence of two eight-marker CC signatures (EpiSwitch®® NST) in whole blood that allow diagnosis of CRC and precancerous polyps, respectively. Independent validation cohort testing demonstrated high accuracy in identifying colorectal polyps and early versus late stages of CRC with an exceptionally high sensitivity of 79-90% and a high positive prediction value of 60-84%. Linking the top diagnostic CCs to nearby genes, we have built pathways maps that likely underline processes contributing to the pathology of polyp and CRC progression, including TGFβ, cMYC, Rho GTPase, ROS, TNFa/NFκB, and APC.

T Cells Instruct Immune Checkpoint Inhibitor Therapy Resistance in Tumors Responsive to IL1 and TNFα Inflammation

Resistance to immune checkpoint inhibitors (ICI) is common, even in tumors with T-cell infiltration. We thus investigated consequences of ICI-induced T-cell infiltration in the microenvironment of resistant tumors. T cells and neutrophil numbers increased in ICI-resistant tumors following treatment, in contrast to ICI-responsive tumors. Resistant tumors were distinguished by high expression of IL1 receptor 1, enabling a synergistic response to IL1 and TNFα to induce G-CSF, CXCL1, and CXCL2 via NF-κB signaling, supporting immunosuppressive neutrophil accumulation in tumor. Perturbation of this inflammatory resistance circuit sensitized tumors to ICIs. Paradoxically, T cells drove this resistance circuit via TNFα both in vitro and in vivo. Evidence of this inflammatory resistance circuit and its impact also translated to human cancers. These data support a mechanism of ICI resistance, wherein treatment-induced T-cell activity can drive resistance in tumors responsive to IL1 and TNFα, with important therapeutic implications.

Ferroptotic Neutrophils Induce Immunosuppression and Chemoresistance in Breast Cancer

Inducing ferroptosis in tumor cells is emerging as a strategy for treating malignancies that are refractory to traditional treatment modalities. However, the consequences of ferroptosis of immune cells in the tumor microenvironment need to be better understood in order to realize the potential of this approach. In this study, we discovered that neutrophils in chemoresistant breast cancer are highly sensitive to ferroptosis. Reduction of the acyltransferase MOAT1 in chemoresistance-associated neutrophils induced phospholipid reprogramming, switching the preference from monounsaturated fatty acids to polyunsaturated fatty acids, which increased their susceptibility to ferroptosis. Ferroptotic neutrophils secreted PGE2, IDO, and oxidized lipids that suppressed the proliferation and cytotoxicity of antitumor CD8+ T cells. Furthermore, neutrophil ferroptosis was closely related to a distinct subset of IL1β+CXCL3+CD4+ (Fer-CD4) T lymphocytes, which were enriched in chemoresistant tumors. Fer-CD4 T cells orchestrated neutrophil ferroptosis by modulating MOAT1 expression via IL1β/IL1R1/NF-κB signaling. Moreover, Fer-CD4 T cells secreted CXCL3, IL8, and S100A9 to replenish the neutrophil pool in the tumor microenvironment. Ferroptotic neutrophils in turn fostered Fer-CD4 T-cell differentiation. In spontaneous tumorigenesis mouse models, targeting IL1β+ CD4+ T cells or IL1R1+ neutrophils broke the cross-talk, restraining neutrophil ferroptosis, enhancing antitumor immunity, and overcoming chemoresistance. Overall, these findings uncover the role of neutrophil ferroptosis in shaping the immune landscape and propose appealing targets for restoring immunosurveillance and chemosensitivity in breast cancer. Significance: In chemoresistant breast cancer, IL1β+CXCL3+CD4+ T cells mediate neutrophil ferroptosis that suppresses antitumor immunity, indicating that interfering with this intercellular cross-talk could be an attractive strategy to reverse chemoresistance.

Neuro-Mesenchymal Interaction Mediated by a β2-Adrenergic Nerve Growth Factor Feedforward Loop Promotes Colorectal Cancer Progression

SIGNIFICANCE

Our work demonstrates that the bidirectional interplay between sympathetic nerves and NGF-expressing CAFs drives colorectal tumorigenesis. This study also offers novel mechanistic insights into catecholamine action in colorectal cancer. Inhibiting the neuro-mesenchymal interaction by TRK blockade could be a potential strategy for treating colorectal cancer.

Cancer-associated fibroblasts as therapeutic targets for cancer: advances, challenges, and future prospects

Research into cancer treatment has been mainly focused on developing therapies to directly target cancer cells. Over the past decade, extensive studies have revealed critical roles of the tumour microenvironment (TME) in cancer initiation, progression, and drug resistance. Notably, cancer-associated fibroblasts (CAFs) have emerged as one of the primary contributors in shaping TME, creating a favourable environment for cancer development. Many preclinical studies have identified promising targets on CAFs, demonstrating remarkable efficacy of some CAF-targeted treatments in preclinical models. Encouraged by these compelling findings, therapeutic strategies have now advanced into clinical evaluation. We aim to provide a comprehensive review of relevant subjects on CAFs, including CAF-related markers and targets, their multifaceted roles, and current landscape of ongoing clinical trials. This knowledge can guide future research on CAFs and advocate for clinical investigations targeting CAFs.

Spatial and single-cell transcriptomics reveal cellular heterogeneity and a novel cancer-promoting Treg cell subset in human clear-cell renal cell carcinoma

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is the most common histologic type of RCC. However, the spatial and functional heterogeneity of immunosuppressive cells and the mechanisms by which their interactions promote immunosuppression in the ccRCC have not been thoroughly investigated.

METHODS

To further investigate the cellular and regional heterogeneity of ccRCC, we analyzed single-cell and spatial transcriptome RNA sequencing data from four patients, which were obtained from samples from multiple regions, including the tumor core, tumor-normal interface, and distal normal tissue. On the basis, the findings were investigated in vitro using tissue and blood samples from 15 patients with ccRCC and validated in the broader samples on tissue microarrays.

RESULTS

In this study, we revealed previously unreported subsets of both stromal and immune cells, as well as mapped their spatial location at finer resolution. In addition, we validated the clusters of tumor cells after removing batch effects according to six characterized gene sets, including epithelial-mesenchymal transitionhigh clusters, metastatic clusters and proximal tubulehigh clusters. Importantly, we identified a special regulatory T (Treg) cell subpopulation that has the molecular characteristics of terminal effector Treg cells but expresses multiple cytokines, such as interleukin (IL)-1β and IL-18. This group of Treg cells has stronger immunosuppressive function and was associated with a worse prognosis in ccRCC cohorts. They were colocalized with MRC1 + FOLR2 + tumor-associated macrophages (TAMs) at the tumor-normal interface to form a positive feedback loop, maintaining a synergistic procarcinogenic effect. In addition, we traced the origin of IL-1β+ Treg cells and revealed that IL-18 can induce the expression of IL-1β in Treg cells via the ERK/NF-κB pathway.

CONCLUSIONS

We demonstrated a novel cancer-promoting Treg cell subset and its interactions with MRC1 + FOLR2 +TAMs, which provides new insight into Treg cell heterogeneity and potential therapeutic targets for ccRCC.

Immune Microenvironment and the Effect of Vascular Endothelial Growth Factor Inhibition in Hepatocellular Carcinoma

Systemic therapy for unresectable hepatocellular carcinoma (HCC) has progressed with the development of multiple kinases, such as vascular endothelial growth factor (VEGF) signaling, targeting cancer growth and angiogenesis. Additionally, the efficacy of sorafenib, regorafenib, lenvatinib, ramucirumab, and cabozantinib has been demonstrated in various clinical trials, and they are now widely used in clinical practice. Furthermore, the development of effective immune checkpoint inhibitors has progressed in systemic therapy for unresectable HCC, and atezolizumab + bevacizumab (atezo/bev) therapy and durvalumab + tremelimumab therapy are now recommended as first-line treatment. Atezo/bev therapy, which combines an anti-programmed cell death 1 ligand 1 antibody with an anti-VEGF antibody, is the first cancer immunotherapy to demonstrate efficacy against unresectable HCC. With the increasing popularity of these treatments, VEGF inhibition is attracting attention from the perspective of its anti-angiogenic effects and impact on the cancer-immune cycle. In this review, we outline the role of VEGF in the tumor immune microenvironment and cancer immune cycle in HCC and outline the potential immune regulatory mechanisms of VEGF. Furthermore, we consider the potential significance of the dual inhibition of angiogenesis and immune-related molecules by VEGF, and ultimately aim to clarify the latest treatment strategies that maximizes efficacy.

Inflammatory Mesenchymal Stromal Cells and IFN-responsive T cells are key mediators of human bone marrow niche remodeling in CHIP and MDS

Somatic mutations in hematopoietic stem/progenitor cells (HSPCs) can lead to clonal hematopoiesis of indeterminate potential (CHIP), potentially progressing to myelodysplastic syndromes (MDS). Here, we investigated how CHIP and MDS remodel the human bone marrow (BM) niche relative to healthy elderly donors, using single cell and anatomical analyses in a large BM cohort. We found distinct inflammatory remodeling of the BM in CHIP and MDS. Furthermore, the stromal compartment progressively lost its HSPC-supportive adipogenic CXCL12-abundant reticular cells while an inflammatory mesenchymal stroma cell (iMSCs) population emerged in CHIP, which expanded in MDS. iMSCs exhibited distinct functional signatures in CHIP and MDS, retaining residual HSPC-support and angiogenic activity in MDS, corresponding with an increase in microvasculature in the MDS niche. Additionally, an IFN-responsive T cell population was linked to fueling inflammation in the stroma. Overall, these findings open new avenues for early intervention in hematological malignancies.

Targeting the JAK-STAT pathway in colorectal cancer: mechanisms, clinical implications, and therapeutic potential

Colorectal cancer (CRC) remains one of the most prevalent and fatal malignancies worldwide, consistently ranking among the top three in terms of incidence and mortality. Despite notable advancements in early detection and therapeutic interventions, survival outcomes for advanced-stage CRC are still dismal, largely due to issues such as drug resistance and metastasis. Recent research has increasingly implicated the JAK-STAT signaling pathway as a pivotal contributor to CRC pathogenesis. This evolutionarily conserved pathway plays a key role in transmitting extracellular signals to the nucleus, thereby modulating gene expression involved in numerous fundamental biological processes. In CRC, dysregulation of the JAK-STAT pathway is frequently observed and is strongly associated with tumor progression, including processes such as cellular proliferation, apoptosis, metastasis, immune evasion, and the sustenance of cancer stem cells. Given its integral role in CRC advancement, the JAK-STAT pathway has gained recognition as a viable therapeutic target. Extensive evidence from preclinical and clinical models supports the efficacy and safety of targeting components of the JAK-STAT pathway, presenting new therapeutic possibilities for patients with CRC, particularly in addressing drug resistance and enhancing treatment outcomes. This review offers a detailed exploration of the JAK-STAT pathway, focusing on its regulatory mechanisms in CRC-related malignancies. Moreover, it examines the association between JAK-STAT protein expression, clinical features, prognosis, and its therapeutic potential in CRC management.

Understanding and measuring mechanical signals in the tumor stroma

The tumor microenvironment (TME) is well known for its immune suppressive role, especially in solid tumors which are characterized by a thick, dense stroma. Apart from cell-cell interactions and biochemical signals, the tumor stroma is also characterized by its distinct mechanical properties, which are dictated by the composition and architecture of its extracellular matrix (ECM). Cancer-associated fibroblasts (CAFs) are the main producers and remodelers of the stromal ECM, and their heterogeneity has recently become a focus of intense research. This review describes recent findings highlighting CAF subtypes and their specific functions, as well as the development of 3D models to study tumor stroma mechanics in vitro. Finally, we discuss the quantitative techniques used to measure tissue mechanical properties at different scales. Given the diagnostic and prognostic value of stroma stiffness and composition, and the recent development of anti-tumor therapeutic strategies targeting the stroma, understanding and measuring tumor stroma mechanical properties has never been more timely or relevant.

Cancer-associated fibroblasts shape early myeloid cell response to chemotherapy-induced immunogenic signals in next generation tumor organoid cultures

BACKGROUND

Patient-derived colorectal cancer (CRC) organoids (PDOs) solely consisting of malignant cells led to major advances in the understanding of cancer treatments. Yet, a major limitation is the absence of cells from the tumor microenvironment, thereby prohibiting potential investigation of treatment responses on immune and structural cells. Currently there are sparse reports describing the interaction of PDOs, cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) in complex primary co-culture assay systems.

METHODS

Primary PDOs and patient matched CAF cultures were generated from surgical resections. Co-culture systems of PDOs, CAFs and monocytic myeloid cells were set up to recapitulate features seen in patient tumors. Single-cell transcriptomics and flow cytometry was used to show effects of culture systems on TAM populations in the co-culture assays under chemotherapeutic and oncolytic viral treatment.

RESULTS

In contrast to co-cultures of tumor cells and monocytes, CAF/monocyte co-cultures and CAF/monocyte/tumor cell triple cultures resulted in a partial differentiation into macrophages and a phenotypic switch, characterized by the expression of major immunosuppressive markers comparable to TAMs in CRC. Oxaliplatin and 5-fluorouracil, the standard-of-care chemotherapy for CRC, induced polarization of macrophages to a pro-inflammatory phenotype comparable to the immunogenic effects of treatment with an oncolytic virus. Monitoring phagocytosis as a functional proxy to macrophage activation and subsequent onset of an immune response, revealed that chemotherapy-induced cell death, but not virus-mediated cell death, is necessary to induce phagocytosis of CRC cells. Moreover, CAFs enhanced the phagocytic activity in chemotherapy treated CRC triple cultures.

CONCLUSIONS

Primary CAF-containing triple cultures successfully model TAM-like phenotypes ex vivo and allow the assessment of their functional and phenotypic changes in response to treatments following a precision medicine approach.

Hematopoietic aging promotes cancer by fueling IL-1⍺-driven emergency myelopoiesis

Age is a major risk factor for cancer, but how aging impacts tumor control remains unclear. In this study, we establish that aging of the immune system, regardless of the age of the stroma and tumor, drives lung cancer progression. Hematopoietic aging enhances emergency myelopoiesis, resulting in the local accumulation of myeloid progenitor-like cells in lung tumors. These cells are a major source of interleukin (IL)-1⍺, which drives the enhanced myeloid response. The age-associated decline of DNA methyltransferase 3A enhances IL-1⍺ production, and disrupting IL-1 receptor 1 signaling early during tumor development normalized myelopoiesis and slowed the growth of lung, colonic, and pancreatic tumors. In human tumors, we identified an enrichment for IL-1⍺-expressing monocyte-derived macrophages linked to age, poorer survival, and recurrence, unraveling how aging promotes cancer and offering actionable therapeutic strategies.

Serotonylation in tumor-associated fibroblasts contributes to the tumor-promoting roles of serotonin in colorectal cancer

Accumulated studies have highlighted the diverse roles of 5-hydroxytryptamine (5-HT), or serotonin, in cancer biology, particularly in colorectal cancer (CRC). While 5-HT primarily exerts its effects through binding to various 5-HT receptors, receptor-independent mechanisms such as serotonylation remain unclear. This study revealed that depleting 5-HT, either through genetic silencing of Tph1 or using a selective TPH1 inhibitor, effectively reduced the growth of CRC tumors. Interestingly, although intrinsic 5-HT synthesis exists in CRC, it is circulating 5-HT that mediates the cancer-promoting function of 5-HT. Blocking the function of 5-HT receptors showed that the oncogenic roles of 5-HT in CRC operate through a mechanism that is separate from its receptor. Instead, serotonylation of histone H3Q5 (H3Q5ser) was found in CRC cells and cancer-associated fibroblasts (CAFs). H3Q5ser triggers a phenotypic switch of CAFs towards an inflammatory-like CAF (iCAF) subtype, which further enhances CRC cell proliferation, invasive characteristics, and macrophage polarization. Knockdown of the 5-HT transporter SLC22A3 or inhibition of TGM2 reduces H3Q5ser levels and reverses the tumor-promoting phenotypes of CAFs in CRC. Collectively, this study sheds light on the serotonylation-dependent mechanisms of 5-HT in CRC progression, offering insights into potential therapeutic strategies targeting the serotonin pathway for CRC treatment.

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.

Dysfunctional tumor-infiltrating Vδ1 + T lymphocytes in microsatellite-stable colorectal cancer

Although γδ T cells are known to participate in immune dysregulation in solid tumors, their relevance to human microsatellite-stable (MSS) colorectal cancer (CRC) is still undefined. Here, using integrated gene expression analysis and T cell receptor sequencing, we characterized γδ T cells in MSS CRC, with a focus on Vδ1 + T cells. We identified Vδ1+ T cells with shared motifs in the third complementarity-determining region of the δ-chain, reflective of antigen recognition. Changes in gene and protein expression levels suggested a dysfunctional effector state of Vδ1+ T cells in MSS CRC, distinct from Vδ1+ T cells in microsatellite-instable (MSI). Interaction analysis highlighted an immunosuppressive role of fibroblasts in the dysregulation of Vδ1+ T cells in MSS CRC via the TIGIT-NECTIN2 axis. Blocking this pathway with a TIGIT antibody partially restored cytotoxicity of the dysfunctional Vδ1 phenotype. These results define an operative pathway in γδ T cells in MSS CRC.

Localized in vivo gene editing of murine cancer-associated fibroblasts

Discovering the role of fibroblasts residing in the tumor microenvironment (TME) requires controlled, localized perturbations because fibroblasts play critical roles in regulating immunity and tumor biology at multiple sites. Systemic perturbations can lead to unintended, confounding secondary effects, and methods to locally genetically engineer fibroblasts are lacking. To specifically investigate murine stromal cell perturbations restricted to the TME, we developed an adeno-associated virus (AAV)-based method to target any gene-of-interest in fibroblasts at high efficiency (>80%). As proof of concept, we generated single (sKO) and double gene KOs (dKO) of Osmr, Tgfbr2, and Il1r1 in cancer-associated fibroblasts (CAFs) and investigated how their cell states and those of other cells of the TME subsequently change in mouse models of melanoma and pancreatic ductal adenocarcinoma (PDAC). Furthermore, we developed an in vivo knockin-knockout (KIKO) strategy to achieve long-term tracking of CAFs with target gene KO via knocked-in reporter gene expression. This validated in vivo gene editing toolbox is fast, affordable, and modular, and thus holds great potential for further exploration of gene function in stromal cells residing in tumors and beyond.

Decoding immune-related gene-signatures in colorectal neoplasia

Background

Colorectal cancer (CRC) is a significant health issue, with notable incidence rates in Norway. The immune response plays a dual role in CRC, offering both protective effects and promoting tumor growth. This research aims to provide a detailed screening of immune-related genes and identify specific genes in CRC and adenomatous polyps within the Norwegian population, potentially serving as detection biomarkers.

Methods

The study involved 69 patients (228 biopsies) undergoing colonoscopy, divided into CRC, adenomatous polyps, and control groups. We examined the expression of 579 immune genes through nCounter analysis emphasizing differential expression in tumor versus adjacent non-tumorous tissue and performed quantitative reverse transcription polymerase chain reaction (RT-qPCR) across patient categories.

Results

Key findings include the elevated expression of CXCL1, CXCL2, IL1B, IL6, CXCL8 (IL8), PTGS2, and SPP1 in CRC tissues. Additionally, CXCL1, CXCL2, IL6, CXCL8, and PTGS2 showed significant expression changes in adenomatous polyps, suggesting their early involvement in carcinogenesis.

Conclusions

This study uncovers a distinctive immunological signature in colorectal neoplasia among Norwegians, highlighting CXCL1, CXCL2, IL1B, IL6, CXCL8, PTGS2, and SPP1 as potential CRC biomarkers. These findings warrant further research to confirm their role and explore their utility in non-invasive screening strategies.

A comprehensive review of phytochemicals targeting macrophages for the regulation of colorectal cancer progression

BACKGROUND

Phytochemicals are natural compounds derived from plants, and are now at the forefront of anti-cancer research. Macrophage immunotherapy plays a crucial role in the treatment of colorectal cancer (CRC). In the context of colorectal cancer, which remains highly prevalent and difficult to treat, it is of research value to explore the potential mechanisms and efficacy of phytochemicals targeting macrophages for CRC treatment.

PURPOSE

The aim of this study was to gain insight into the role of phytochemical-macrophage interactions in regulating CRC and to provide a theoretical basis for the development of new therapeutic strategies in the future.

STUDY DESIGN

This review discusses the potential immune mechanisms of phytochemicals for the treatment of CRC by summarizing research of phytochemicals targeting macrophages.

METHODS

We reviewed the PubMed, EMBASE, Web of Science and CNKI databases from their initial establishment to July 2023 to classify and summaries phytochemicals according to their mechanism of action in targeting macrophages.

RESULTS

The results of the literature review suggest that phytochemicals interfere with CRC development by affecting macrophages through four main mechanisms. Firstly, they modulate the production of cytotoxic substances, such as NO and ROS, by macrophages to exert anticancer effects. Secondly, phytochemicals polarize macrophages towards the M1 phenotype, inhibit M2 polarisation and enhance the anti-tumour immune responses. Thirdly, they enhance the secretion of macrophage-derived cytokines and alter the tumour microenvironment, thereby inhibiting tumor growth. Finally, they activate the immune response by targeting macrophages, triggering the recruitment of other immune cells, thereby enhancing the immune killing effect and exerting anti-tumor effects. These findings highlight phytochemicals as potential therapeutic strategies to intervene in colorectal cancer development by modulating macrophage activity, providing a strong theoretical basis for future clinical applications.

CONCLUSION

Phytochemicals exhibit potential anti-tumour effects by modulating macrophage activity and intervening in the colorectal cancer microenvironment by multiple mechanisms.

Exploring the diversity of cancer-associated fibroblasts: insights into mechanisms of drug resistance

Introduction: Among the various stromal cell types within the tumor microenvironment, cancer-associated fibroblasts (CAFs) emerge as the predominant constituent, exhibiting a diverse array of oncogenic functions not intrinsic to normal fibroblasts. Their involvement spans across all stages of tumorigenesis, encompassing initiation, progression, and metastasis. Current understanding posits the coexistence of distinct subpopulations of CAFs within the tumor microenvironment across a spectrum of solid tumors, showcasing both pro- and antitumor activities. Recent advancements in single-cell transcriptomics have revolutionized our ability to meticulously dissect the heterogeneity inherent to CAF populations. Furthermore, accumulating evidence underscores the pivotal role of CAFs in conferring therapeutic resistance to tumors against various drug modalities. Consequently, efforts are underway to develop pharmacological agents specifically targeting CAFs. Methods: This review embarks on a comprehensive analysis, consolidating data from 36 independent single-cell RNA sequencing investigations spanning 17 distinct human malignant tumor types. Results: Our exploration centers on elucidating CAF population markers, discerning their prognostic relevance, delineating their functional contributions, and elucidating the underlying mechanisms orchestrating chemoresistance. Discussion: Finally, we deliberate on the therapeutic potential of harnessing CAFs as promising targets for intervention strategies in clinical oncology.

Interleukin-1β: Friend or foe for gastrointestinal cancers

Gastrointestinal (GI) cancer is a malignancy arising in the digestive system and accounts for approximately a third of increasing global cancer-related mortality, especially in the colorectum, esophagus, stomach, and liver. Interleukin-1β (IL-1β) is a leukocytic pyrogen recognized as a tumor progression-related cytokine. IL-1β secretion and maturation in inflammatory responses could be regulated by nuclear factor-kappaB-dependent expression of NLR family pyrin domain containing 3, inflammasome formation, and activation of IL-1 converting enzyme. Several studies have documented the pro-tumorigenic effects of IL-1β in tumor microenvironments, promoting proliferation and metastatic potential of cancer cells in vitro and tumorigenesis in vivo. The application of IL-1β inhibitors is also promising for targeted therapy development in some cancer types. However, as a leukocytic pro-inflammatory cytokine, IL-1β may also possess anti-tumorigenic effects and be type-specific in different cancers. This editorial discusses the up-to-date roles of IL-1β in GI cancers, including underlying mechanisms and downstream signaling pathways. Understanding and clarifying the roles of IL-1β would significantly benefit future therapeutic targeting and help improve therapeutic outcomes in patients suffering from GI cancer.

CPT1C-positive cancer-associated fibroblast facilitates immunosuppression through promoting IL-6-induced M2-like phenotype of macrophage

Cancer-associated fibroblasts (CAFs) exhibit remarkable phenotypic heterogeneity, with specific subsets implicated in immunosuppression in various malignancies. However, whether and how they attenuate anti-tumor immunity in gastric cancer (GC) remains elusive. CPT1C, a unique isoform of carnitine palmitoyltransferase pivotal in regulating fatty acid oxidation, is briefly indicated as a protumoral metabolic mediator in the tumor microenvironment (TME) of GC. In the present study, we initially identified specific subsets of fibroblasts exclusively overexpressing CPT1C, hereby termed them as CPT1C+CAFs. Subsequent findings indicated that CPT1C+CAFs fostered a stroma-enriched and immunosuppressive TME as they correlated with extracellular matrix-related molecular features and enrichment of both immunosuppressive subsets, especially M2-like macrophages, and multiple immune-related pathways. Next, we identified that CPT1C+CAFs promoted the M2-like phenotype of macrophage in vitro. Bioinformatic analyses unveiled the robust IL-6 signaling between CPT1C+CAFs and M2-like phenotype of macrophage and identified CPT1C+CAFs as the primary source of IL-6. Meanwhile, suppressing CPT1C expression in CAFs significantly decreased IL-6 secretion in vitro. Lastly, we demonstrated the association of CPT1C+CAFs with therapeutic resistance. Notably, GC patients with high CPT1C+CAFs infiltration responded poorly to immunotherapy in clinical cohort. Collectively, our data not only present the novel identification of CPT1C+CAFs as immunosuppressive subsets in TME of GC, but also reveal the underlying mechanism that CPT1C+CAFs impair tumor immunity by secreting IL-6 to induce the immunosuppressive M2-like phenotype of macrophage in GC.

Crosstalk between cancer-associated fibroblasts and regulated cell death in tumors: insights into apoptosis, autophagy, ferroptosis, and pyroptosis

Cancer-associated fibroblasts (CAFs), the main stromal component of the tumor microenvironment (TME), play multifaceted roles in cancer progression through paracrine signaling, exosome transfer, and cell interactions. Attractively, recent evidence indicates that CAFs can modulate various forms of regulated cell death (RCD) in adjacent tumor cells, thus involving cancer proliferation, therapy resistance, and immune exclusion. Here, we present a brief introduction to CAFs and basic knowledge of RCD, including apoptosis, autophagy, ferroptosis, and pyroptosis. In addition, we further summarize the different types of RCD in tumors that are mediated by CAFs, as well as the effects of these modes of RCD on CAFs. This review will deepen our understanding of the interactions between CAFs and RCD and might offer novel therapeutic avenues for future cancer treatments.

Myeloid Cell-Derived IL-1 Signaling Damps Neuregulin-1 from Fibroblasts to Suppress Colitis-Induced Early Repair of the Intestinal Epithelium

Neuregulin-1 (Nrg1, gene symbol: Nrg1), a ligand of the ErbB receptor family, promotes intestinal epithelial cell proliferation and repair. However, the dynamics and accurate derivation of Nrg1 expression during colitis remain unclear. By analyzing the public single-cell RNA-sequencing datasets and employing a dextran sulfate sodium (DSS)-induced colitis model, we investigated the cell source of Nrg1 expression and its potential regulator in the process of epithelial healing. Nrg1 was majorly expressed in stem-like fibroblasts arising early in mouse colon after DSS administration, and Nrg1-Erbb3 signaling was identified as a potential mediator of interaction between stem-like fibroblasts and colonic epithelial cells. During the ongoing colitis phase, a significant infiltration of macrophages and neutrophils secreting IL-1β emerged, accompanied by the rise in stem-like fibroblasts that co-expressed Nrg1 and IL-1 receptor 1. By stimulating intestinal or lung fibroblasts with IL-1β in the context of inflammation, we observed a downregulation of Nrg1 expression. Patients with inflammatory bowel disease also exhibited an increase in NRG1+IL1R1+ fibroblasts and an interaction of NRG1-ERBB between IL1R1+ fibroblasts and colonic epithelial cells. This study reveals a novel potential mechanism for mucosal healing after inflammation-induced epithelial injury, in which inflammatory myeloid cell-derived IL-1β suppresses the early regeneration of intestinal tissue by interfering with the secretion of reparative neuregulin-1 by stem-like fibroblasts.

Forces at play: exploring factors affecting the cancer metastasis

Metastatic disease, a leading and lethal indication of deaths associated with tumors, results from the dissemination of metastatic tumor cells from the site of primary origin to a distant organ. Dispersion of metastatic cells during the development of tumors at distant organs leads to failure to comply with conventional treatments, ultimately instigating abrupt tissue homeostasis and organ failure. Increasing evidence indicates that the tumor microenvironment (TME) is a crucial factor in cancer progression and the process of metastatic tumor development at secondary sites. TME comprises several factors contributing to the initiation and progression of the metastatic cascade. Among these, various cell types in TME, such as mesenchymal stem cells (MSCs), lymphatic endothelial cells (LECs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), T cells, and tumor-associated macrophages (TAMs), are significant players participating in cancer metastasis. Besides, various other factors, such as extracellular matrix (ECM), gut microbiota, circadian rhythm, and hypoxia, also shape the TME and impact the metastatic cascade. A thorough understanding of the functions of TME components in tumor progression and metastasis is necessary to discover new therapeutic strategies targeting the metastatic tumor cells and TME. Therefore, we reviewed these pivotal TME components and highlighted the background knowledge on how these cell types and disrupted components of TME influence the metastatic cascade and establish the premetastatic niche. This review will help researchers identify these altered components' molecular patterns and design an optimized, targeted therapy to treat solid tumors and restrict metastatic cascade.

Interleukin-1 receptor antagonist: An alternative therapy for cancer treatment

The interleukin-1 receptor antagonist (IL-1Ra) is an anti-inflammatory cytokine and a naturally occurring antagonist of the IL-1 receptor. It effectively counteracts the IL-1 signaling pathway mediated by IL-1α/β. Over the past few decades, accumulating evidence has suggested that IL-1 signaling plays an essential role in tumor formation, growth, and metastasis. Significantly, anakinra, the first United States Food and Drug Administration (FDA)-approved IL-1Ra drug, has demonstrated promising antitumor effects in animal studies. Numerous clinical trials have subsequently incorporated anakinra into their cancer treatment protocols. In this review, we comprehensively discuss the research progress on the role of IL-1 in tumors and summarize the significant contribution of IL-1Ra (anakinra) to tumor immunity. Additionally, we analyze the potential value of IL-1Ra as a biomarker from a clinical perspective. This review is aimed to highlight the important link between inflammation and cancer and provide potential drug targets for future cancer therapy.

The cancer-immunity cycle: Indication, genotype, and immunotype

The cancer-immunity cycle provides a framework to understand the series of events that generate anti-cancer immune responses. It emphasizes the iterative nature of the response where the killing of tumor cells by T cells initiates subsequent rounds of antigen presentation and T cell stimulation, maintaining active immunity and adapting it to tumor evolution. Any step of the cycle can become rate-limiting, rendering the immune system unable to control tumor growth. Here, we update the cancer-immunity cycle based on the remarkable progress of the past decade. Understanding the mechanism of checkpoint inhibition has evolved, as has our view of dendritic cells in sustaining anti-tumor immunity. We additionally account for the role of the tumor microenvironment in facilitating, not just suppressing, the anti-cancer response, and discuss the importance of considering a tumor's immunological phenotype, the "immunotype". While these new insights add some complexity to the cycle, they also provide new targets for research and therapeutic intervention.