T Cells in Colorectal Cancer: Unravelling the Function of Different T Cell Subsets in the Tumor Microenvironment

Combination therapy with immune checkpoint inhibitors in colorectal cancer: Challenges, resistance mechanisms, and the role of microbiota

Colorectal cancer (CRC) is still one of the leading causes of cancer deaths worldwide. Even though there has been progress in cancer immunotherapy, the results of applying immune checkpoint inhibitors (ICIs) have been unsatisfactory, especially in microsatellite stable (MSS) CRC. Single-agent ICIs that target programmed cell death-1 (PD-1)/ PD-L1, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), T cell Ig- and mucin-domain-containing molecule-3 (TIM-3), and lymphocyte activation gene (LAG)-3 have emerged as having specific benefits. However, many primary and secondary resistance mechanisms are available in the tumor microenvironment (TME) that prevent it from happening. Combination strategies, such as the use of anti-PD-1 and anti-CTLA-4, can be effective in overcoming these resistance pathways, but toxicities remain a significant concern. Moreover, ICIs have been integrated with various treatment modalities, including chemotherapy, radiotherapy, antibiotics, virotherapy, polyadenosine diphosphate-ribose polymerase (PARP) inhibitors, and heat shock protein 90 (HSP90) inhibitors. The outcomes observed in both preclinical and clinical settings have been encouraging. Interestingly, manipulating gut microbiota via fecal microbiota transplantation (FMT) has been identified as a new strategy to increase the efficacy of immunotherapy in CRC patients. Therefore, integrating ICIs with other treatment approaches holds promise in enhancing the prognosis of CRC patients. This review focuses on the unmet need for new biomarkers to select patients for combination therapies and the ongoing work to overcome resistance and immune checkpoint blockade.

Multidimensional differences of right- and left-sided colorectal cancer and their impact on targeted therapies

Despite advances in metastatic colorectal cancer (mCRC) treatment, long-term survival remains poor, particularly in right-sided colorectal cancer (RCRC), which has a worse prognosis compared to left-sided CRC (LCRC). This disparity is driven by the complex biological diversity of these malignancies. RCRC and LCRC differ not only in clinical presentation and outcomes but also in their underlying molecular and genetic profiles. This article offers a detailed literature review focusing on the distinctions between RCRC and LCRC. We explore key differences across embryology, anatomy, pathology, omics, and the tumor microenvironment (TME), providing insights into how these factors contribute to prognosis and therapeutic responses. Furthermore, we examine the therapeutic implications of these differences, considering whether the conventional classification of CRC into right- and left-sided forms should be refined. Recent molecular findings suggest that this binary classification may overlook critical biological complexities. Therefore, we propose that future approaches should integrate molecular insights to better guide personalized treatments, especially anti-EGFR therapies, and improve patient outcomes.

Exploring the Role of Cellular Interactions in the Colorectal Cancer Microenvironment

Colorectal cancer (CRC) stands as one of the tumors with globally high incidence and mortality rates. In recent years, researchers have extensively explored the role of the tumor immune microenvironment (TME) in CRC, highlighting the crucial influence of immune cell populations in driving tumor progression and shaping therapeutic outcomes. The TME encompasses an array of cellular and noncellular constituents, spanning tumor cells, immune cells, myeloid cells, and tumor-associated fibroblasts, among others. However, the cellular composition within the TME is highly dynamic, evolving throughout different stages of tumor progression. These shifts in cell subpopulation proportions lead to a gradual transition in the immune response, shifting from an early antitumor growth to a late-stage environment that supports tumor survival. Therefore, it is crucial to further investigate and understand the complex interactions among the various cell populations within the TME. In this review, we explore the key cellular components of varying origins, subpopulations with shared origins, and noncellular elements within the CRC TME, examining their interconnections and critical considerations for developing personalized and precise immunotherapy strategies.

Adoptive immune cell therapy for colorectal cancer

Colorectal cancer (CRC) is a major cause of cancer-related morbidity and mortality worldwide, with limited options for patients at advanced stages. Immunotherapy, particularly immune cell-based therapies, has gained significant attention as an innovative approach for targeting CRC. This review summarizes the progress in various immune cell therapies, including DC vaccine, CAR/TCR-T cells, CAR-NK cells et al, each engineered to recognize and attack cancer cells expressing specific antigens. CAR-T cell therapy, which has been successful in hematologic cancers, faces challenges in CRC due to the solid tumor microenvironment, which limits cell infiltration and persistence. CAR-NK cells, CAR-M and CAR-γδ T cells, however, offer alternative strategies due to their unique properties, such as the ability to target tumor cells without prior sensitization and a lower risk of inducing severe cytokine release syndrome. Recent advances in lentiviral transduction have enabled effective expression of CARs on NK and γδ T cells, providing promising preclinical results in CRC models. This review explores the mechanisms, tumor targets, preclinical studies, and early-phase clinical trials of these therapies, addressing key challenges such as enhancing specificity to tumor antigens and overcoming the immunosuppressive tumor microenvironment. The potential of combination therapies, including immune checkpoint inhibitors and cytokine therapy, is also discussed some as a means to improve the effectiveness of immune cell-based treatments for CRC. Continued research is essential to translate these promising approaches into clinical settings, offering new hope for CRC patients.

Targeting stemness pathways modulates macrophage polarization and reprograms the tumor microenvironment

Introduction

The tumor microenvironment plays a pivotal role in cancer progression and therapeutic resistance, with tumor-associated macrophages significantly influencing immune suppression and tumor growth. Colorectal cancers (CRC) classified as Consensus Molecular Subtype 4 (CMS4) and triple-negative breast cancers subsets are particularly characterized by a mesenchymal phenotype, immune exclusion, and extensive macrophage infiltration. This study aimed to investigate how targeting cancer cell stemness with specific inhibitors could modulate macrophage polarization in CRC in vitro and breast cancer in vivo, potentially shifting the immune balance from pro-tumor M2-like to anti-tumor M1-like macrophages.

Methods

We used four stemness inhibitors-salinomycin, SB-431542, JIB-04, and napabucasin-each targeting different pathways (Wnt/β-catenin, TGF-β, histone demethylation, and STAT3, respectively), to evaluate their effects on CMS4 CRC cell lines (HCT116 and SW620) and human peripheral blood-derived macrophages in an indirect co-culture model.

Results

Our results showed that CMS4 CRC cell lines induced distinct macrophage polarization patterns, with HCT116 promoting M2-like macrophages and SW620 leaning toward M1-like profile. Notably, the combination of stemness inhibitors reduced stemness markers (CD133, CD44) in colorectal cancer cells and shifted macrophage polarization toward an M1-like phenotype, particularly in co-culture with HCT116. In vivo studies using the syngeneic immunocompetent EO771 breast cancer mouse model demonstrated that combination of stemness inhibitors increased the M1/M2 macrophage ratio.

Conclusions

Our study highlights the dual potential of stemness inhibitors to target both cancer cells and the immune microenvironment. These findings offer promising strategies for enhancing favorable immunomodulation in mesenchymal-like colorectal tumors.

Causal relationship between immune cell signatures and colorectal cancer: a bi-directional, two-sample mendelian randomization study

BACKGROUND

Prior studies have demonstrated the association between immune cells and colorectal cancer (CRC). However, the causal link to specific immunophenotypes is limited. This study intends to elucidate the causal relationship of immune cell signatures on CRC.

METHODS

We performed a bi-directional and two-sample mendelian randomization (MR) study, utilizing GWAS summary data of 731 immune cell traits (n = 3,757) and CRC statistics (n = 470,002). The primary MR methodology was inverse-variance weighted (IVW) method. Furthermore, heterogeneity was evaluated by Cochran's Q test. MR-PRESSO and MR-Egger were employed to assess horizontal and vertical pleiotropy respectively. Sensitivity analysis and FDR correction were conducted in our results. These results were validated in both the UK Biobank and FinnGen cohorts. We also extracted transcriptomic data of CRC and adjacent non-tumor tissues from TCGA, and used CIBERSORT to compare the infiltration patterns of 22 immune cell panels between normal tissues and the tumor microenvironment (TME).

RESULTS

Our study indicated nine immune cell signatures had significant causality with the risk of CRC after sensitivity analysis and FDR correction. The positive results covered four panels: B cell, CD8 + T cell, Treg, and monocyte. IgD- CD38br and IgD + CD38br B cell, CD8dim and CD28 + CD45RA- CD8dim T cell, and CD14 on CD14 + CD16- monocyte were the protective factors of CRC. However, CD39 + resting Treg, CX3CR1 on CD14- CD16 + monocyte, FSC-A on HLA DR + T cell, and BAFF-R on B cell increased the risk of CRC. The results were validated in the UK Biobank data and FinnGen cohorts. The data from the TCGA database also confirmed the infiltration of B cell, CD8 + T cell, Treg, and monocyte panels in the TME.

CONCLUSION

This study highlights the causal link between specific immune cell phenotypes and CRC, providing valuable insights into the immune microenvironment's role in CRC. The validation of our findings using large-scale datasets (UK Biobank, FinnGen) and TCGA underscores the robustness of our results, offering new potential therapeutic targets for CRC treatment.

Combination of potassium oxonate with anti-PD-1 for the treatment of colorectal cancer

Introduction

Identification of effective therapies for colorectal cancer (CRC) remains an urgent medical need, especially for the microsatellite stable (MSS) phenotype. In our previous study, potassium oxonate (PO), a uricase inhibitor commonly used for elevating uric acid in mice, unexpectedly showed remarkable inhibition of tumor growth when combined with anti-programmed death-1 (PD-1). Further research demonstrated that the combination of potassium oxonate and anti-PD-1 could reprogram the immune microenvironment. This study aimed to explore the anti-tumor effect of PO combined with anti-PD-1, and investigate the impact on the immunosuppressive tumor microenvironment (TME).

Methods

We established a syngeneic mouse model of CRC and divided into groups of control group, single drugs group of PO and anti-PD-1, and the combination group. Use the HE staining, immunohistochemistry (IHC) and TUNEL staining of tumor issues to verify the anti-neoplasm of each group. We also tested the changes of TME through flow cytometry of spleen of mice in each group, as well as the IHC of cytokines.

Results

The co-therapy of PO and anti-PD-1 showed admirable anti-tumor effect compared with the control group and the single drug groups. The TME were tended to an environment beneficial for killing tumors by enhancing chemotactic factor release, increasing CD8+ T cell infiltration and activation, and decreasing the amount of regulatory T cells. Moreover, IFN-γ and IL-2 secretion were found to be enriched in the tumor TME.

Conclusion

Our study indicated that combination of PO and anti-PD-1 could synergistically suppress CRC progression and altered the tumor microenvironment in favor of antitumor immune responses.

CD155 promotes the progression of colorectal cancer by restraining CD8+ T cells via the PI3K/AKT/NF-κB pathway

BACKGROUND

CD155 is a crucial factor in the regulation of T cell function and contributes to immune escape. CD155 upregulation has been found in several types of cancer. However, the mechanism by which CD155 regulates CD8+ T cell function in colorectal cancer remains unclear. Here we investigated the role and mechanism of CD155 in the regulation of CD8+ T cell function.

METHODS

We studied the expression of CD155 in colorectal cancer tissues through western blot, immunohistochemistry, and the TCGA database. We verified the effects of CD155 on the functions of colorectal cancer cells and CD8+ T cells through in vitro experiments. We demonstrated that CD155 affects CD8+ T cell migration and thus promotes tumor growth in a mouse subcutaneous tumor model. We then tested the changes in the PI3K/AKT/NF-κB pathway in CD8+ T cells by flow cytometry.

RESULTS

We demonstrated that stable CD155 expression was negatively correlated with prognosis in colorectal cancer patients. In vitro experiments confirmed that CD155 does not affect tumor cell proliferation, migration, or invasion. We also revealed that CD155 downregulated the function and migration of CD8+ T cells in vivo and in vitro. Furthermore, CD155 might regulate CD8+ T cells function via the PI3K/AKT/NF-κB pathway.

CONCLUSION

This study revealed that CD155 can promote the progression of colorectal cancer by regulating the PI3K / AKT-NF-κB pathway to promote the depletion of CD8+ T cells and reduce their migration to the tumor microenvironment. CD155 may become an important prognostic biomarker and an effective target for colorectal cancer immunotherapy.

The expression of ERAP1 is favorable for the prognosis and immunotherapy in colorectal cancer: a study based on the bioinformatic and immunohistochemical analysis

BACKGROUND

Endoplasmic reticulum aminopeptidase 1 (ERAP1) is an emerging pharmacological target in cancer immunotherapy. This study was set out to examine the expression profiles and implications for prognosis and immunotherapy of ERAP1 in CRC.

METHODS

Based on bioinformatics and immunohistochemical analysis, we analyzed ERAP1 for potential diagnostic and prognostic significance in CRC. Functional enrichment analysis was conducted to detect the pathways associated with ERAP1, thus determining possible mechanisms. ESTIMATE, TIMER, and CIBESORT probed the links between ERAP1 and tumor-infiltrating immune cells. Lastly, we examined how ERAP1 expression correlated with the sensitivity to immunotherapy.

RESULTS

Tumor tissues had decreased levels of ERAP1 expression relative to normal tissues. Patients whose ERAP1 expression was low suffered a worse chance of survival. Besides, it was shown that ERAP1 expression was associated with the advanced M stage and pathologic stage. Survival analysis revealed that low ERAP1 expression, age, pathologic stage, T stage, and M stage were independent indicators for unfavorable CRC patients' prognoses. The 1-, 3-, and 5-year OS calibration curves all fit well with the ideal model, suggesting that the age-ERAP1-T-stage-M-stage nomogram is a reliable predictor of OS. Additionally, we discovered that ERAP1 expression was associated with immune response and infiltration of various immune cells, such as down-regulated inhibitory immune cells and up-regulated stimulating immune cells. Sensitivity to PD-1 and CTLA4 inhibitors was associated with high ERAP1 levels.

CONCLUSIONS

In summary, ERAP1 has potential as a diagnostic and prognostic biological marker, highlighting new insights into the study of CRC and the design of effective therapies.

Saffron improves the efficacy of immunotherapy for colorectal cancer through the IL-17 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Saffron is one of the traditional medicinal herbs, which contains various active ingredients, such as safranal, crocin, saffron acid, etc. It has anti-inflammatory, antioxidant, and anti-cancer properties, and is widely used in clinical practice. The anti-cancer efficacy of saffron has been previously confirmed, but its anti-cancer mechanism in colorectal cancer remains unclear.

OBJECTIVE

We investigated the effect of active compounds of saffron on the efficacy of immunotherapy for colorectal cancer.

METHODS

TCMSP and liquid chromatography-mass spectrometry analysis (LC-MS), GeneCards, and DisGeNET databases were used to identify the active compounds of saffron, drug targets and the disease targets of colorectal cancer. They were then subjected to Gene Ontology Enrichment (GO) and Signalling Pathway Enrichment (KEGG) analyses. The core targets and corresponding compounds were selected for molecular docking. The effect of active components of saffron on the proliferation of CT26 and HCT116 cells was investigated using the cell counting kit-8 (CCK-8). In vitro experiments were conducted by subcutaneous injection of CT26 cells to establish a colon cancer model. Enzyme-linked immunosorbent assay (ELISA), western blotting (WB), real-time polymerase chain reaction (RT-PCR), immunohistochemistry (IHC), and flow cytometry (FCM) were employed to validate the effects of saffron on colorectal cancer immunotherapy.

RESULTS

1. LC-MS analysis revealed that the main active component of saffron extract was crocin. The active chemicals of saffron intersected with 170 colorectal cancer targets, with 17 predicting targets for saffron treatment. GO and KEGG enrichment analyses revealed that the active components of saffron can prevent colorectal cancer development by enhancing Th17 cell differentiation and the IL-17 signaling pathway. 2. In vitro studies revealed that saffron alcohol extract, crocin, and safranal can suppress the proliferation of CT26 and HCT116 cells. 3. In vivo studies showed that crocin and safranal can increase the body mass and decrease the tumor mass of loaded mice, decrease the serum level of IL-17, and lower the mRNA expression level of IL-17, IL-6, TNF-α, TGF-β, and PD-L1 and IL-17, PD-L1 protein in tumors. This inhibitory effect was strengthened after combined immunotherapy. In addition, saffron modulated CD4+ and CD8+ T cells and the CD4+/CD8+T ratio in mouse spleens.

CONCLUSION

The active components of saffron can reduce the expression of inflammatory factors and ameliorate the immunological microenvironment of tumors via the IL-17 signaling pathway, thereby improving the efficacy of immunotherapy for colorectal cancer. This study provides pharmacological support for the application of saffron in enhancing the efficacy of immunotherapy for colorectal cancer.

Prognostic models of immune-related cell death and stress unveil mechanisms driving macrophage phenotypic evolution in colorectal cancer

BACKGROUND

Tumor microenvironment (TME), particularly immune cell infiltration, programmed cell death (PCD) and stress, has increasingly become a focal point in colorectal cancer (CRC) treatment. Uncovering the intricate crosstalk between these factors can enhance our understanding of CRC, guide therapeutic strategies, and improve patient prognosis.

METHODS

We constructed an immune-related cell death and stress (ICDS) prognostic model utilizing machine learning methodologies. Furthermore, we performed enrichment analyses and deconvolution algorithms to elucidate the complex interactions between immune cell infiltration and the processes of PCD and stress within a substantial array of transcriptomic data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus data base (GEO) related to CRC. Single-cell sequencing and biochemical experiments were used to validate the interaction between the model genes and programmed cell death in tumor cells.

RESULTS

The ICDS prognostic model exhibited robust predictive performance in seven independent cohorts, revealing an inverse correlation between model scores and patient prognosis. Meanwhile, the ICDS index was positively correlated with clinical stage. Model analysis indicated that patient subgroups with low ICDS index exhibited heightened immune activation features and elevated activity in PCD and stress pathways. Single-cell analysis further revealed that macrophages were the central drivers of immune characteristics underlying prognostic differences within the ICDS prognostic model. Pseudotime analysis and cellular experiments indicated that the model gene GAL3ST4 promotes the transition of macrophages toward an M2 pro-tumor phenotype. Furthermore, cell communication analysis and experimental validation revealed that the cuproptosis in tumor cells suppress GAL3ST4 expression, thereby inhibiting M2-like macrophage polarization.

CONCLUSION

In summary, we constructed the ICDS prognostic model and uncovered the mechanism by which tumor cells downregulate GAL3ST4 expression via cuproptosis to inhibit M2-like macrophage polarization, providing new targets and biomarkers for CRC treatment and prognosis evaluation.

The characteristics of the tumor immune microenvironment in colorectal cancer with different MSI status and current therapeutic strategies

Colorectal cancer (CRC) remains a significant cause of cancer-related mortality worldwide. Despite advancements in surgery, chemotherapy, and radiotherapy, the effectiveness of these conventional treatments is limited, particularly in advanced cases. Therefore, transition to novel treatment is urgently needed. Immunotherapy, especially immune checkpoint inhibitors (ICIs), has shown promise in improving outcomes for CRC patients. Notably, patients with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) tumors often benefit from ICIs, while the majority of CRC cases, which exhibit proficient mismatch repair (pMMR) or microsatellite-stable (MSS) status, generally show resistance to this approach. It is assumed that the MSI phenotype cause some changes in the tumor microenvironment (TME), thus triggering antitumor immunity and leading to response to immunotherapy. Understanding these differences in the TME relative to MSI status is essential for developing more effective therapeutic strategies. This review provides an overview of the TME components in CRC and explores current approaches aimed at enhancing ICI efficacy in MSS CRC.

Tumor-Infiltrating Immune Cells in Colorectal Cancer

Colorectal cancer encompasses a heterogeneous group of malignancies that differ in pathophysiological mechanisms, immune response and infiltration, therapeutic response, and clinical prognosis. Numerous studies have highlighted the clinical relevance of tumor-infiltrating immune cells among different types of colorectal tumors yet vary in cell type definitions and cell identification strategies. The distinction of immune signatures is particularly challenging when several immune subtypes are involved but crucial to identify novel intercellular mechanisms within the tumor microenvironment. In this review, we compile human and non-human studies on tumor-infiltrating immune cells and provide an overview of immune subtypes, their pathophysiological functions, and their prognostic role in colorectal cancer. We discuss how differentiating immune signatures can guide the development of immunotherapeutic targets and personalized treatment regimens. We analyzed comprehensive human protein biomarker profiles across the entire immune spectrum to improve interpretability and application of tumor studies and to ultimately enhance immunotherapy and advance precision medicine for colorectal cancer patients.

Causal impacts of 731 immunocyte phenotypes on colorectal cancer-evidence from a bidirectional two-sample Mendelian randomization

Colorectal cancer is one of the most common and lethal malignancies, and various factors have been confirmed to contribute to its occurrence. However, the causal role of immune cell-specific changes in the development of colorectal cancer has not been investigated. The bidirectional two-sample Mendelian randomization analysis was performed to explore the association between 731 types of immune cell phenotypes-specific changes and colorectal cancer. The inverse variance weighting results indicated that a total of 31 and 28 immune cell phenotypes significantly associated with colorectal cancer in two different datasets, respectively. The primary results of inverse variance weighting Mendelian randomization suggested that the immune cell phenotypes BAFF-R on IgD+ CD38dim (OR = 1.033, 95%CI: 1.005-1.062) and SSC-A on monocyte (OR = 1.055, 95%CI: 1.016-1.096) served as risk factor for colorectal cancer. In addition, the meta-analysis further supports the causal link of BAFF-R on IgD+ CD38dim (pooled OR = 1.035, 95%CI: 1.013-1.059) and SSC-A on monocyte (pooled OR = 1.060, 95%CI: 1.026-1.095) with colorectal cancer. Finally, the inverse variance weighting Mendelian randomization result suggested that genetic determinants of colorectal cancer may decrease the level of HLA DR++ monocyte absolute count (OR = 0.686, 95%CI: 0.508-0.925). Our results indicated that the potential causal association of BAFF-R on IgD+ CD38dim and SSC-A on monocyte with colorectal cancer. The identified immune cells may be appealing drug targets for colorectal cancer, but lack confirmation from real clinical evidence. Further studies are needed to investigate the roles of these immune cells in colorectal cancer.

Association between somatic microsatellite instability, hypermutation status, and specific T cell subsets in colorectal cancer tumors

Background

Microsatellite instability-high (MSI-high) tumors comprise ~15% of sporadic colorectal cancers (CRC) and are associated with elevated T cell infiltration. However, the universality of this response across T cell subtypes with distinct functions is unknown.

Methods

Including 1,236 CRC tumors from three observational studies, we conducted in-situ T cell profiling using a customized 9-plex (CD3, CD4, CD8, CD45RA, CD45RO, FOXP3, KRT, MKI67, and DAPI) multispectral immunofluorescence assay. MSI status was assessed through polymerase chain reaction or immunohistochemical assays. We used multivariable ordinal logistic regression to estimate odds ratios (OR per increasing quantile) and 95% confidence intervals (CIs) for the association of MSI status with quantiles of T cell densities in either tumor epithelial or stromal tissue areas.

Results

Compared to microsatellite instability low or microsatellite stable (MSI-low/MSS) tumors, MSI-high status was associated with higher density for the majority of immune subsets (twelve out of eighteen) in both epithelial and stromal tissue areas. The strongest associations were for CD3+CD8+ T cells in epithelial areas [OR (95% CI) for naive, memory, and regulatory subsets = 3.49 (2.57, 4.75); 2.82 (2.10, 3.78); 3.04 (2.24, 4.13), respectively]. Conversely, stromal area CD3+CD4+ memory T cells were inversely associated [OR (95% CI) = 0.68 (0.51, 0.91)].

Discussion

MSI-high status was strongly associated with higher densities of most T cell subsets in both epithelial and stromal tissue areas. Our investigation supports efforts to identify patients who may be more likely to respond to current immunotherapy treatments.

Significance

This study helps us better understand how a clinically relevant tumor phenotype, microsatellite instability status, is related to different functioning T cell densities in colorectal tumors, which may impact future immunotherapy strategies.

Adaptive Immune Receptor Distinctions Along the Colorectal Polyp-Tumor Timelapse

INTRODUCTION

Colorectal cancer (CRC) is the third-most common cancer diagnosed worldwide, with 1.85 million new cases per year. While mortality has significantly decreased due to preventive colonoscopy, only 5% of polyps identified progress to cancer. Studies have found that immunological alterations in other solid tumor microenvironments are associated with worse prognoses.

METHODS

We applied an immunogenomics approach to assess adaptive immune receptor gene expression changes that were associated with development of adenocarcinoma, utilizing 79 samples that represented normal, tubular, villous, and tumor colorectal tissue for 32 patients.

RESULTS

Results indicated that the number of productive TRD and TRG recombination reads, representing gamma-delta (γδ) T-cells, significantly decreased with progression from normal to tumor tissue. A further assessment of two independent CRC datasets was consistent with a decrease in TRD recombination reads with progression to CRC. Further, we identified three physicochemical parameters for immunoglobulin, complementarity determining region-3 (CDR3) amino acids associated with progression from normal to tumor tissue.

CONCLUSIONS

Overall, this study points towards a need for further investigation of γδ T-cells in relation to CRC development; and indicates immunoglobulin CDR3 physicochemical features as potential CRC biomarkers.

Shengqiyichang decoction regulates antitumor immunity in colorectal cancer by downregulating lymphocyte antigen 6 family member G6D via the protein kinase B/p38 mitogen-activated protein kinase signaling pathway

The traditional Chinese medicine (TCM) formulation Shengqiyichang Decoction (SQYCD) has been reported to stimulate host immunity, and it has been administered for the treatment of colorectal cancer (CRC). Here, we applied network and bioinformatics analyses to elucidate the mechanisms by which SQYCD ameliorates CRC and validated its modes of action via in vivo and in vitro experiments. We identified 46 active compounds in SQYCD and selected 237 proteins as potential therapeutic targets in CRC, most notably p38 mitogen-activated protein kinase (p38⍺). Bioinformatics analyses demonstrated differential expression in CRC tissues and prognostic value of the genes encoding TNFα, MAPK14, CASP-3, MAPK1, AKT1, PRKACA, VEGF, IL-6, EGFR and ESR1. We then plotted receiver operating curves (ROC) and time-ROC for the differentially expressed genes (DEGs) ESR1 and AKT1 to predict the progress of CRC. We speculated that the AKT/p38α-MAPK signaling pathway is associated with the clinical prognosis of CRC. In a mouse model, we found that SQYCD inhibits CRC tumor growth by increasing CD4+ and CD8+ T cell abundance and decreasing the ratio of T-regulatory cells (Tregs) in the tumor microenvironment. In cultured mouse CRC cells, SQYCD selectively upregulated levels of the CRC-associated protein lymphocyte antigen 6 family member G6D, while the AKT activator SC-79 reversed this effect. The discoveries made herein suggest that SQYCD exerts a therapeutic effect in CRC by inhibiting Treg recruitment via inhibition of the AKT/p38α/LY6G6D signaling axis.

Fibroblast activation protein constitutes a novel target of chimeric antigen receptor T-cell therapy in solid tumors

With recent advances in tumor immunotherapy, chimeric antigen receptor T (CAR-T) cell therapy has achieved unprecedented success in several hematologic tumors, significantly improving patient prognosis. However, in solid tumors, the efficacy of CAR-T cell therapy is limited because of high antigen uncertainty and the extremely restrictive tumor microenvironment (TME). This challenge has led to the exploration of new targets, among which fibroblast activation protein (FAP) has gained attention for its relatively stable and specific expression in the TME of various solid tumors, making it a potential new target for CAR-T cell therapy. This study comprehensively analyzed the biological characteristics of FAP and discussed its potential application in CAR-T cell therapy, including the theoretical basis, and preclinical and clinical research progress of targeting FAP with CAR-T cell therapy for solid tumor treatment. The challenges and future optimization directions of this treatment strategy were also explored, providing new perspectives and strategies for CAR-T cell therapy in solid tumors.

Th17 cell function in cancers: immunosuppressive agents or anti-tumor allies?

T helper (Th) 17 cells, a distinct subset of Th lymphocytes, are known for their prominent interleukin (IL)-17 production and other pro-inflammatory cytokines. These cells exhibit remarkable plasticity, allowing them to exhibit different phenotypes in the cancer microenvironment. This adaptability enables Th17 cells to promote tumor progression by immunosuppressive activities and angiogenesis, but also mediate anti-tumor immune responses through employing immune cells in tumor setting or even by directly converting toward Th1 phenotype and producing interferon-gamma (IFN-γ). This dual role of Th17 cells in cancer makes it a double-edged sword in encountering cancer. In this review, we aim to elucidate the complexities of Th17 cell function in cancer by summarizing recent studies and, ultimately, to design novel therapeutic strategies, especially targeting Th17 cells in the tumor milieu, which could pave the way for more effective cancer treatments.

Some Glycoproteins Expressed on the Surface of Immune Cells and Cytokine Plasma Levels Can Be Used as Potential Biomarkers in Patients with Colorectal Cancer

Colorectal cancer (CRC) is a leading cause of mortality worldwide. Its incidence holds a major position among the most common life-threatening diseases. Hence, the early identification and precise characterization of disease activity based on proper biomarkers are of utmost importance for therapeutic strategy and patient survival. The identification of new biomarkers for colorectal cancer or disease-specific levels/combinations of biomarkers will significantly contribute to precise diagnosis and improved personalized treatment of patients. Therefore, the present study aims to identify colorectal cancer-specific immunological biomarkers. The plasma levels of several cytokines (interleukin-1β /IL-1β/, IL-2, IL-4, IL-10, IL-12, IL-15, TGFβ and IFNγ) of 20 patients with colorectal cancer and 21 healthy individuals were determined by ELISA. The expression of several types of glycoproteins on the surface of peripheral blood leukocytes isolated from CRC patients and healthy volunteers was evaluated by flow cytometry. Correlations between cytokine levels and cell surface glycoprotein expression were analyzed. The obtained results demonstrated significantly elevated levels of CD80, CD86, CD279 and CD274 expressing leukocyte populations in the cancer patient group, while the numbers of NK cells and CD8- and CD25-positive cells were decreased. Based on these data and the correlations with cytokine levels, it can be concluded that CD25, CD80, CD86, CD274 and CD279 glycoproteins combined with specific plasma levels of IL-1β, IL-2, IL-15 and TGFβ could represent potential biomarkers for colorectal cancer.

Impact of gut microbiota and its metabolites on immunometabolism in colorectal cancer

Colorectal cancer (CRC) is highly prevalent, accounting for approximately one-tenth of cancer cases and deaths globally. It stands as the second most deadly and third most common cancer type. Although the gut microbiota has been implicated in CRC carcinogenesis for the last several decades, it remains one of the least understood risk factors for CRC development, as the gut microbiota is highly diverse and variable. Many studies have uncovered unique microbial signatures in CRC patients compared with healthy matched controls, with variations dependent on patient age, disease stage, and location. In addition, mechanistic studies revealed that tumor-associated bacteria produce diverse metabolites, proteins, and macromolecules during tumor development and progression in the colon, which impact both cancer cells and immune cells. Here, we summarize microbiota's role in tumor development and progression, then we discuss how the metabolic alterations in CRC tumor cells, immune cells, and the tumor microenvironment result in the reprogramming of activation, differentiation, functions, and phenotypes of immune cells within the tumor. Tumor-associated microbiota also undergoes metabolic adaptation to survive within the tumor environment, leading to immune evasion, accumulation of mutations, and impairment of immune cells. Finally, we conclude with a discussion on the interplay between gut microbiota, immunometabolism, and CRC, highlighting a complex interaction that influences cancer development, progression, and cancer therapy efficacy.

Characterization of the AGR2-NPM3 axis uncovers the AGR2 involvement in PD-L1 regulation in colorectal cancer

Despite extensive research, the molecular role of AGR2 in the progression and metastasis of colorectal cancer (CRC) has not been fully characterized. We used quantitative mass spectrometry (SWATH MS) to identify differentially expressed proteins in paired CRC cell models of the SW480 and SW620 cell lines in response to AGR2 protein level manipulation. Relying on the results from SWATH MS and subsequent immunochemical validation, we selected NMP3 as the top candidate protein associated with AGR2 in CRC tumour cells in our screen. RT‒qPCR and immunochemical analysis confirmed the involvement of AGR2-mediated regulation of NPM3 at the transcriptional and posttranscriptional levels. Since PD-L1 is a constituent of the NPM3 regulatory axis, we aimed to correlate the changes in PD-L1 to the differential expression of AGR2 in our cell models. We found that AGR2 positively regulates PD-L1 levels in both SW480 and SW620 cell lines; additionally, several different CRC patient transcriptome cohorts confirmed the association of AGR2 with PD-L1. Our work reveals a new AGR2-NPM3 regulatory axis and the involvement of AGR2 in the regulation of PD-L1, which paves the way for the association of AGR2 with immune evasion in CRC cells.

Challenges in validation of combination treatment strategies for CRC using patient-derived organoids

Patient-derived organoids (PDOs) established from tissues from various tumor types gave the foundation of ex vivo models to screen and/or validate the activity of many cancer drug candidates. Due to their phenotypic and genotypic similarity to the tumor of which they were derived, PDOs offer results that effectively complement those obtained from more complex models. Yet, their potential for predicting sensitivity to combination therapy remains underexplored. In this review, we discuss the use of PDOs in both validation and optimization of multi-drug combinations for personalized treatment strategies in CRC. Moreover, we present recent advancements in enriching PDOs with diverse cell types, enhancing their ability to mimic the complexity of in vivo environments. Finally, we debate how such sophisticated models are narrowing the gap in personalized medicine, particularly through immunotherapy strategies and discuss the challenges and future direction in this promising field.

From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

Immune landscape and response to oncolytic virus-based immunotherapy

Oncolytic virus (OV)-based immunotherapy has emerged as a promising strategy for cancer treatment, offering a unique potential to selectively target malignant cells while sparing normal tissues. However, the immunosuppressive nature of tumor microenvironment (TME) poses a substantial hurdle to the development of OVs as effective immunotherapeutic agents, as it restricts the activation and recruitment of immune cells. This review elucidates the potential of OV-based immunotherapy in modulating the immune landscape within the TME to overcome immune resistance and enhance antitumor immune responses. We examine the role of OVs in targeting specific immune cell populations, including dendritic cells, T cells, natural killer cells, and macrophages, and their ability to alter the TME by inhibiting angiogenesis and reducing tumor fibrosis. Additionally, we explore strategies to optimize OV-based drug delivery and improve the efficiency of OV-mediated immunotherapy. In conclusion, this review offers a concise and comprehensive synopsis of the current status and future prospects of OV-based immunotherapy, underscoring its remarkable potential as an effective immunotherapeutic agent for cancer treatment.

Identification of a Gene Expression Signature to Predict the Risk of Early Recurrence and the Degree of Immune Cell Infiltration in Triple-negative Breast Cancer

BACKGROUND/AIM

Patients with triple-negative breast cancer (TNBC) have a high rate of recurrence within 3 years of diagnosis and a high rate of death within 5 years compared to other subtypes. The number of clinical trials investigating various new agents and combination therapies has recently increased; however, current strategies benefit only a minority of patients. This study aimed to identify specific genes that predict patients at high risk of recurrence and the immune status of the tumor microenvironment at an early stage, thereby providing insight into potential therapeutic targets to improve clinical outcomes in TNBC patients.

MATERIALS AND METHODS

We evaluated the prognostic significance of microarray mRNA expression of 20,603 genes in 233 TNBC patients from the METABRIC dataset and further validated the results using RNA-seq mRNA expression data in 143 TNBC patients from the GSE96058 dataset.

RESULTS

Eighteen differentially expressed genes (AKNA, ARHGAP30, CA9, CD3D, CD3G, CD6, CXCR6, CYSLTR1, DOCK10, ENO1, FLT3LG, IFNG, IL2RB, LPXN, PRKCB, PVRIG, RASSF5, and STAT4) identified in both datasets were found to be reliable biomarkers for predicting TNBC recurrence and progression. Notably, the genes whose low expression was associated with increased risk of recurrence and death were immune-related genes, with significant differences in levels of immune cell infiltration in the tumor microenvironment between high- and low- expression groups.

CONCLUSION

Genes reported herein may be effective biomarkers to identify TNBC patients who will and will not benefit from immunotherapy and may be particularly important genes for developing future treatment strategies, including immunotherapy.

Relationship of FDG PET/CT imaging features with tumor immune microenvironment and prognosis in colorectal cancer: a retrospective study

BACKGROUND

Imaging features of colorectal cancers on 2-deoxy-2-[18F]fluoro-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT) have been considered to be affected by tumor characteristics and tumor immune microenvironment. However, the relationship between PET/CT imaging features and immune reactions in tumor tissue has not yet been fully evaluated. This study investigated the association of FDG PET/CT imaging features in the tumor, bone marrow, and spleen with immunohistochemical results of cancer tissue and recurrence-free survival (RFS) in patients with colorectal cancer.

METHODS

A total of 119 patients with colorectal cancer who underwent FDG PET/CT for staging work-up and received curative surgical resection were retrospectively enrolled. From PET/CT images, 10 first-order imaging features of primary tumors, including intensity of FDG uptake, volumetric metabolic parameters, and metabolic heterogeneity parameters, as well as FDG uptake in the bone marrow and spleen were measured. The degrees of CD4+, CD8+, and CD163 + cell infiltration and interleukin-6 (IL-6) and matrix metalloproteinase-11 (MMP-11) expression were graded through immunohistochemical analysis of surgical specimens. The relationship between FDG PET/CT imaging features and immunohistochemical results was assessed, and prognostic significance of PET/CT imaging features in predicting RFS was evaluated.

RESULTS

Correlation analysis with immunohistochemistry findings showed that the degrees of CD4 + and CD163 + cell infiltration and IL-6 and MMP-11 expression were correlated with cancer imaging features on PET/CT. Patients with enhanced inflammatory response in cancer tissue demonstrated increased FDG uptake, volumetric metabolic parameters, and metabolic heterogeneity. FDG uptake in the bone marrow and spleen was positively correlated with the degree of CD163 + cell infiltration and IL-6 expression, respectively. In multivariate survival analysis, the coefficient of variation of FDG uptake in the tumor (p = 0.019; hazard ratio, 0.484 for 0.10 increase) and spleen-to-liver uptake ratio (p = 0.020; hazard ratio, 24.901 for 1.0 increase) were significant independent predictors of RFS.

CONCLUSIONS

The metabolic heterogeneity of tumors and FDG uptake in the spleen were correlated with tumor immune microenvironment and showed prognostic significance in predicting RFS in patients with colorectal cancer.