The Cytokine Network in Colorectal Cancer: Implications for New Treatment Strategies

NFκB signalling in colorectal cancer: Examining the central dogma of IKKα and IKKβ signalling

The NFκB pathway, known as the central regulator of inflammation, has a well-established role in colorectal cancer (CRC) initiation, progression, and therapy resistance. Due to the pathway's overarching roles in CRC, there have been efforts to characterise NFκB family members and target the pathway for therapeutic intervention. Initial research illustrated that the canonical NFκB pathway, driven by central kinase IKKβ, was a promising target for drug intervention. However, dose limiting toxicities and specificity concerns have resulted in failure of IKKβ inhibitors in clinical trials. The field has turned to look at targeting the less dominant kinase, IKKα, which along with NFκB inducing kinase (NIK), drives the lesser researched non-canonical NFκB pathway. However prognostic studies of the non-canonical pathway have produced conflicting results. There is emerging evidence that IKKα is involved in other signalling pathways, which lie outside of canonical and non-canonical NFκB signalling. Evidence suggests that some of these alternative pathways involve a truncated form of IKKα, and this may drive poor cancer-specific survival in CRC. This review aims to explore the multiple components of NFκB signalling, highlighting that NIK may be the central kinase for non-canonical NFκB signalling, and that IKKα is involved in novel pathways which promote CRC.

Colorectal ALOX15 as a host factor determinant of EPA and DHA effects on colorectal carcinogenesis

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), omega-3 polyunsaturated fatty acids (ω-3 PUFAs) derived from fish oil, are widely used as dietary supplements and FDA-approved treatments for hypertriglyceridemia. However, studies investigating the effects of EPA and DHA on colorectal carcinogenesis (CRC) have yielded conflicting results. The factors that determine these discrepant results remain unknown. Resolvins, oxidative metabolites of EPA and DHA, inhibit key pro-tumorigenic cytokine and chemokine signaling of colorectal cancer (e.g., IL-6, IL-1β, and CCL2). 15-lipoxygenase-1 (ALOX15), a critical enzyme for resolvin generation is commonly lost during human CRC. Whether ALOX15 expression, as a host factor, modulates the effects of EPA and DHA on CRC remains unknown. Therefore, we evaluated the effects of ALOX15 transgenic expression in colonic epithelial cells on resolvin generation by EPA and DHA and CRC in mouse models representative of human CRC. Our results revealed that 1) EPA and DHA effects on CRC were diverse, ranging from suppressive to promotive, and these effects were occasionally altered by the formulations of EPA and DHA (free fatty acid, ethyl ester, triglyceride); 2) EPA and DHA uniformly suppressed CRC in the presence of intestinal ALOX15 transgenic expression, which induced the production of resolvins, decreased colonic CCL3-5 and CXCL-5 expression and tumor associated macrophages while increasing CD8 T cell abundance in tumor microenvironment; and 3) RvD5, the predominant resolvin produced by ALOX15, inhibited macrophage generation of pro-tumorigenic cytokines. These findings demonstrate the significance of intestinal ALOX15 expression as a host factor in determining the effects of EPA and DHA on CRC.

Significance

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are widely used as dietary supplements and FDA-approved treatments for hypertriglyceridemia. Studies of EPA and DHA effects on colorectal carcinogenesis (CRC) have revealed inconsistencies; factors determining the direction of their impact on CRC have remained unidentified. Our data show that EPA and DHA effects on CRC were divergent and occasionally influenced by their formulations. More importantly, intestinal 15-lipoxgenase-1 (ALOX15) expression modulated EPA and DHA effects on CRC, leading to their consistent suppression of CRC. ALOX15 promoted EPA and DHA oxidative metabolism to generate resolvins, which inhibited key pro-tumorigenic inflammatory cytokines and chemokines, including IL-6. IL-1β, and CCL2. ALOX15 is therefore an important host factor in determining EPA and DHA effects on CRC.

Targeting the "tumor microenvironment": RNA-binding proteins in the spotlight in colorectal cancer therapy

Colorectal cancer (CRC) is the third most common cancer and has the second highest mortality rate among cancers. The development of CRC involves both genetic and epigenetic abnormalities, and recent research has focused on exploring the ex-transcriptome, particularly post-transcriptional modifications. RNA-binding proteins (RBPs) are emerging epigenetic regulators that play crucial roles in post-transcriptional events. Dysregulation of RBPs can result in aberrant expression of downstream target genes, thereby affecting the progression of colorectal tumors and the prognosis of patients. Recent studies have shown that RBPs can influence CRC pathogenesis and progression by regulating various components of the tumor microenvironment (TME). Although previous research on RBPs has primarily focused on their direct regulation of colorectal tumor development, their involvement in the remodeling of the TME has not been systematically reported. This review aims to highlight the significant role of RBPs in the intricate interactions within the CRC tumor microenvironment, including tumor immune microenvironment, inflammatory microenvironment, extracellular matrix, tumor vasculature, and CRC cancer stem cells. We also highlight several compounds under investigation for RBP-TME-based treatment of CRC, including small molecule inhibitors such as antisense oligonucleotides (ASOs), siRNAs, agonists, gene manipulation, and tumor vaccines. The insights gained from this review may lead to the development of RBP-based targeted novel therapeutic strategies aimed at modulating the TME, potentially inhibiting the progression and metastasis of CRC.

Deletion of IL-27p28 induces CD8 T cell immunity against colorectal tumorigenesis

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide, characterized by molecular and clinical heterogeneity. Interleukin (IL)-27, a heterodimeric cytokine composed of p28 and EBI3 subunits, has been reported to exert potent antitumor activity in several cancer models. However, the precise role of IL-27 in the pathogenesis of CRC remains unclear. Here, we show that during the azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC development, IL-27p28 levels are dramatically increased in peripheral blood and tumor tissues, and the cytokine is mainly produced by tumor-infiltrating myeloid cells. IL-27p28 deficient mice display tumor resistances in both inflammation-associated CRC model and syngeneic MC38 colon cancer model. Administration with IL-27p28 neutralizing antibody also reduces the tumor formation in AOM/DSS-treated mice. Mechanically, CD8+ T cells in IL-27p28-/- mice exhibit enhanced tumor infiltration and cytotoxicity, which can be largely attributed to activation of the Akt/mTOR signaling pathway. Furthermore, selective depletion of CD8+ T cells in IL-27p28-/- mice markedly accelerate tumor growth and almost abrogate the protective effects of IL-27p28 deficiency. Most interestingly, the expression of IL-27p28 is also upregulated in tumor tissues of CRC patients and those with high expression of IL-27p28 tend to have a poorer overall survival. Our results suggest that loss of IL-27p28 suppresses colorectal tumorigenesis by augmenting CD8+ T cell-mediated anti-tumor immunity. Targeting IL-27p28 could be developed as a novel strategy for the treatment of colorectal cancers.

Decoding the Tumour Microenvironment: Molecular Players, Pathways, and Therapeutic Targets in Cancer Treatment

The tumour microenvironment (TME) is a complex and constantly evolving collection of cells and extracellular components. Cancer cells and the surrounding environment influence each other through different types of processes. Characteristics of the TME include abnormal vasculature, altered extracellular matrix, cancer-associated fibroblast and macrophages, immune cells, and secreted factors. Within these components, several molecules and pathways are altered and take part in the support of the tumour. Epigenetic regulation, kinases, phosphatases, metabolic regulators, and hormones are some of the players that influence and contribute to shaping the tumour and the TME. All these characteristics contribute significantly to cancer progression, metastasis, and immune escape, and may be the target for new approaches for cancer treatment.

Integrated whole transcriptome profiling revealed a convoluted circular RNA-based competing endogenous RNAs regulatory network in colorectal cancer

Recently, it has been identified that circRNAs can act as miRNA sponge to regulate gene expression in various types of cancers, associating them with cancer initiation and progression. The present study aims to identify colorectal cancer-related circRNAs and the underpinning mechanisms of circRNA/miRNA/mRNA networks in the development and progress of Colorectal Cancer. Differentially expressed circRNAs, miRNAs, and mRNAs were identified in GEO microarray datasets using the Limma package of R. The analysis of differentially expressed circRNAs resulted in 23 upregulated and 31 downregulated circRNAs. CeRNAs networks were constructed by intersecting the results of predicted and experimentally validated databases, circbank and miRWalk, and by performing DEMs and DEGs analysis using Cytoscape. Next, functional enrichment analysis was performed for DEGs included in ceRNA networks. Followed by survival analysis, expression profile assessment using TCGA and GEO data, and ROC curve analysis we identified a ceRNA sub-networks that revealed the potential regulatory effect of hsa_circ_0001955 and hsa_circ_0071681 on survival-related genes, namely KLF4, MYC, CCNA2, RACGAP1, and CD44. Overall, we constructed a convoluted regulatory network and outlined its likely mechanisms of action in CRC, which may contribute to the development of more effective approaches for early diagnosis, prognosis, and treatment of CRC.

Prognostic Value of Circulating Cytokines in Chemorefractory Colorectal Cancer

Circulating cytokines could be optimal biomarkers for prognostication and management decisions in colorectal cancer (CRC). Chemorefractory CRC patients with available plasma samples were included in this study. In the discovery cohort (n = 85), 182 circulating cytokines were tested with a semi-quantitative multiplex assay, and prognostic cytokines were analyzed in the validation cohort (n = 111) by ELISA. Overall survival (OS) was the primary outcome measure, with the false discovery rate (FDR) method (significance level of <0.01) being used to correct for multiple comparisons. Four cytokines were associated with OS in the discovery cohort: insulin-like growth factor-binding protein 1 (IGFBP-1) (HR 2.1 [95%CI: 1.58-2.79], FDR < 0.001), insulin-like growth factor-binding protein 2 (IGFBP-2) (HR 1.65 [95%CI: 1.28-2.13], FDR = 0.006), serum amyloid A (SAA) (HR 1.84 [95%CI: 1.39-2.43], FDR < 0.001), and angiotensin II (HR 1.65 [95%CI: 1.29-2.1], FDR = 0.006). Of these, IGFBP-1 (HR 2.70 [95%CI: 1.56-4.76], FDR = 0.007) and IGFBP-2 (HR 3.33 [95%CI: 1.64-6.67], FDR = 0.008) were confirmed to be independently associated with OS in the validation cohort. Patients with high concentrations of IGFBP-1 and/or IGFBP-2 had a median OS of 3.0 months as compared with 6.9 months for those with low concentrations of both cytokines (HR 2.44 [95%CI: 1.52-4.0], FDR = 0.002) Validation of circulating IGFBP-1 and IGFBP-2 as independent prognostic biomarkers for chemorefractory CRC in larger, independent series is warranted.

Secretome of Dental Pulp-Derived Stem Cells Reduces Inflammation and Proliferation of Glioblastoma Cells by Deactivating Mapk-Akt Pathway

Background

Dental pulp-derived stem cells (DPSC) is a promising therapy as they modulate the immune response, so we evaluated the inhibitory effect of DPSC secretome (DPSC℗) on the proliferation and inflammation in human glioblastoma (GBM) cells (U-87 MG) and elucidated the concomitant mechanisms involved.

Methods

The U87-MG cells were cultured with DPSC℗ for 24 h and assessed the expression of inflammatory molecules using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), generation of reactive oxygen species (ROS), and mitochondrial functionality using a seahorse flux analyzer. MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay and cell cycle analysis were performed to evaluate the proliferation and cell cycle. Finally, the protein levels were determined by western blot.

Results

DPSC℗ reduced the inflammation and proliferation of U-87 MG cells by down-regulating the pro-inflammatory markers and up-regulating anti-inflammatory markers expressions through ROS-mediated signaling. Moreover, DPSC℗ significantly reduced the mitochondrial membrane potential (MMP) in the cells. The cellular bioenergetics revealed that all the parameters of oxygen consumption rate (OCAR) and the extracellular acidification rate (ECAR) were significantly decreased in the GBM cells after the addition of DPSC℗. Additionally, DPSC℗ decreased the GBM cell proliferation by arresting the cell cycle at the G1 phase through activation (phosphorylation) of checkpoint molecule CHK1. Furthermore, mechanistically, we found that the DPSC℗ impedes the phosphorylation of the mitogen-activated protein kinases (P38 MAPK) and protein kinase B (AKT) pathway.

Conclusion

Our findings lend the first evidence of the inhibitory effects of DPSC℗ on proliferation and inflammation in GBM cells by altering the P38 MAPK-AKT pathway.

Gut virome profiling identifies an association between temperate phages and colorectal cancer promoted by Helicobacter pylori infection

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers worldwide. While a close correlation between chronic Helicobacter pylori infection and CRC has been reported, the role of the virome has been overlooked. Here, we infected Apc-mutant mouse models and C57BL/6 mice with H. pylori and conducted a comprehensive metagenomics analysis of H. pylori-induced changes in lower gastrointestinal tract bacterial and viral communities. We observed an expansion of temperate phages in H. pylori infected Apc+/1638N mice at the early stage of carcinogenesis. Some of the temperate phages were predicted to infect bacteria associated with CRC, including Enterococcus faecalis. We also observed a high prevalence of virulent genes, such as flgJ, cwlJ, and sleB, encoded by temperate phages. In addition, we identified phages associated with pre-onset and onset of H. pylori-promoted carcinogenesis. Through co-occurrence network analysis, we found strong associations between the viral and bacterial communities in infected mice before the onset of carcinogenesis. These findings suggest that the expansion of temperate phages, possibly caused by prophage induction triggered by H. pylori infection, may have contributed to the development of CRC in mice by interacting with the bacterial community.

Role of Cytokines and Other Soluble Factors in Tumor Development: Rationale for New Therapeutic Strategies

Many cytokines control tumor development by directly lowering cancer cell proliferation and inducing apoptotic cell death, or indirectly by activating the antitumoral activity of specific immune cells such as NK or CD8+ T-lymphocytes [...].

Reigniting hope in cancer treatment: the promise and pitfalls of IL-2 and IL-2R targeting strategies

Interleukin-2 (IL-2) and its receptor (IL-2R) are essential in orchestrating immune responses. Their function and expression in the tumor microenvironment make them attractive targets for immunotherapy, leading to the development of IL-2/IL-2R-targeted therapeutic strategies. However, the dynamic interplay between IL-2/IL-2R and various immune cells and their dual roles in promoting immune activation and tolerance presents a complex landscape for clinical exploitation. This review discusses the pivotal roles of IL-2 and IL-2R in tumorigenesis, shedding light on their potential as diagnostic and prognostic markers and their therapeutic manipulation in cancer. It underlines the necessity to balance the anti-tumor activity with regulatory T-cell expansion and evaluates strategies such as dose optimization and selective targeting for enhanced therapeutic effectiveness. The article explores recent advancements in the field, including developing genetically engineered IL-2 variants, combining IL-2/IL-2R-targeted therapies with other cancer treatments, and the potential benefits of a multidimensional approach integrating molecular profiling, immunological analyses, and clinical data. The review concludes that a deeper understanding of IL-2/IL-2R interactions within the tumor microenvironment is crucial for realizing the full potential of IL-2-based therapies, heralding the promise of improved outcomes for cancer patients.

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

Therapeutic options for metastatic colorectal cancer (mCRC) are very limited, and the prognosis using combination therapy with a chemotherapeutic drug and a targeted agent, e.g., epidermal growth factor receptor or tyrosine kinase, remains poor. Therefore, mCRC is associated with a poor median overall survival (mOS) of only 25-30 months. Current immunotherapies with checkpoint inhibitor blockade (ICB) have led to a substantial change in the treatment of several cancers, such as melanoma and non-small cell lung cancer. In CRC, ICB has only limited effects, except in patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) tumors, which comprise about 15% of sporadic CRC patients and about 4% of patients with metastatic CRC. The vast majority of sporadic CRCs are microsatellite-stable (MSS) tumors with low levels of infiltrating immune cells, in which immunotherapy has no clinical benefit so far. Immunotherapy with checkpoint inhibitors requires the presence of infiltrating T cells into the tumor microenvironment (TME). This makes T cells the most important effector cells in the TME, as evidenced by the establishment of the immunoscore-a method to estimate the prognosis of CRC patients. The microenvironment of a tumor contains several types of T cells that are anti-tumorigenic, such as CD8⁺ T cells or pro-tumorigenic, such as regulatory T cells (Tregs) or T helper 17 (Th17) cells. However, even CD8⁺ T cells show marked heterogeneity, e.g., they can become exhausted, enter a state of hyporesponsiveness or become dysfunctional and express high levels of checkpoint molecules, the targets for ICB. To kill cancer cells, CD8⁺ T cells need the recognition of the MHC class I, which is often downregulated on colorectal cancer cells. In this case, a population of unconventional T cells with a γδ T cell receptor can overcome the limitations of the conventional CD8⁺ T cells with an αβT cell receptor. γδ T cells recognize antigens in an MHC-independent manner, thus acting as a bridge between innate and adaptive immunity. Here, we discuss the effects of different T cell subsets in colorectal cancer with a special emphasis on γδ T cells and the possibility of using them in CAR-T cell therapy. We explain T cell exclusion in microsatellite-stable colorectal cancer and the possibilities to overcome this exclusion to enable immunotherapy even in these "cold" tumors.

Circulating interleukins and risk of colorectal cancer: a Mendelian randomization study

BACKGROUND

Recent studies have suggested a potential causal association between Interleukins (ILs) and Colorectal Cancer (CRC), and thus, it is important to examine the causal relationship between them using a Mendelian randomization (MR) approach.

METHODS

The instrumental variables were extracted for IL-1ra, IL-6, IL-6ra, IL-8, IL-16, IL-18, IL-27 from genome-wide association studies of European ancestry. Summary statistics of CRC were also retrieved. An inverse variance-weighted MR approach was implemented as the primary method to compute overall effects from multiple instruments. Additional MR approaches and sensitivity and heterogeneity pleiotropy analyses were also conducted respectively.

RESULTS

Our analysis suggested a causal effect between an increase of IL-8 and a reduced risk of CRC (odds ratio 0.65; 95% confidence interval, 0.43-0.98; p = 0.041) and did not provide evidence for causal effects of IL-1ra, IL-6, IL-6ra, IL-16, IL-18, IL-27. Sensitivity analyses suggested the robustness of MR results and that they were unlikely to be affected by unbalanced pleiotropy or significant heterogeneity.

CONCLUSIONS

This study investigated the role of ILs in the development of CRC and we found a causal effect between an increase of IL-8 and a reduced risk of CRC but not found evidence for causal effects of IL-1ra, IL-6, IL-6ra, IL-16, IL-18, IL-27. Sensitivity analyses suggested the robustness of MR results and that they were unlikely to be affected by unbalanced pleiotropy or significant heterogeneity.

Cell Therapy as Target Therapy against Colon Cancer Stem Cells

Cancer stem cells (CSCs) are a small subpopulation of cells within tumors with properties, such as self-renewal, differentiation, and tumorigenicity. CSCs have been proposed as a plausible therapeutic target as they are responsible for tumor recurrence, metastasis, and conventional therapy resistance. Selectively targeting CSCs is a promising strategy to eliminate the propagation of tumor cells and impair overall tumor development. Recent research shows that several immune cells play a crucial role in regulating tumor cell proliferation by regulating different CSC maintenance or proliferation pathways. There have been great advances in cellular immunotherapy using T cells, natural killer (NK) cells, macrophages, or stem cells for the selective targeting of tumor cells or CSCs in colorectal cancer (CRC). This review summarizes the CRC molecular profiles that may benefit from said therapy and the main vehicles used in cell therapy against CSCs. We also discuss the challenges, limitations, and advantages of combining conventional and/or current targeted treatments in the late stages of CRC.

Interleukins (Cytokines) as Biomarkers in Colorectal Cancer: Progression, Detection, and Monitoring

Cancer is the primary cause of death in economically developed countries and the second leading cause in developing countries. Colorectal cancer (CRC) is the third most common cause of cancer-related deaths worldwide. Risk factors for CRC include obesity, a diet low in fruits and vegetables, physical inactivity, and smoking. CRC has a poor prognosis, and there is a critical need for new diagnostic and prognostic biomarkers to reduce related deaths. Recently, studies have focused more on molecular testing to guide targeted treatments for CRC patients. The most crucial feature of activated immune cells is the production and release of growth factors and cytokines that modulate the inflammatory conditions in tumor tissues. The cytokine network is valuable for the prognosis and pathogenesis of colorectal cancer as they can aid in the cost-effective and non-invasive detection of cancer. A large number of interleukins (IL) released by the immune system at various stages of CRC can act as "biomarkers". They play diverse functions in colorectal cancer, and include IL-4, IL-6, IL-8, IL-11, IL-17A, IL-22, IL-23, IL-33, TNF, TGF-β, and vascular endothelial growth factor (VEGF), which are pro-tumorigenic genes. However, there are an inadequate number of studies in this area considering its correlation with cytokine profiles that are clinically useful in diagnosing cancer. A better understanding of cytokine levels to establish diagnostic pathways entails an understanding of cytokine interactions and the regulation of their various biochemical signaling pathways in healthy individuals. This review provides a comprehensive summary of some interleukins as immunological biomarkers of CRC.

Cytokine concentration in peripheral blood of patients with colorectal cancer

Introduction

The role of tumour secretory cytokines and peripheral circulatory cytokines in tumour progression has received increasing attention; however, the role of tumour-related inflammatory cytokines in colorectal cancer (CRC) remains unclear. In this study, the concentrations of various cytokines in the peripheral blood of healthy controls and patients with CRC at different stages were compared.

Methods

Peripheral blood samples from 4 healthy participants and 22 colorectal cancer patients were examined. Luminex beads were used to evaluate concentration levels of 40 inflammatory cytokines in peripheral blood samples.

Results

In peripheral blood, compared with healthy controls and early stage (I + II) CRC patients, advanced CRC (III + IV) patients had increased concentrations of mononuclear/macrophage chemotactic-related proteins (CCL7, CCL8, CCL15, CCL2, and MIF), M2 polarization-related factors (IL-1β, IL-4), neutrophil chemotactic and N2 polarization-related cytokines (CXCL2, CXCL5, CXCL6, IL-8), dendritic cells (DCs) chemotactic-related proteins (CCL19, CCL20, and CCL21), Natural killer (NK) cell related cytokines (CXCL9, CXCL10), Th2 cell-related cytokines (CCL1, CCL11, CCL26), CXCL12, IL-2, CCL25, and CCL27, and decreased IFN-γ and CX3CL1 concentrations. The differential upregulation of cytokines in peripheral blood was mainly concentrated in CRC patients with distant metastasis and was related to the size of the primary tumour; however, there was no significant correlation between cytokine levels in peripheral blood and the propensity and mechanism of lymph node metastasis.

Discussion

Different types of immune cells may share the same chemokine receptors and can co-localise in response to the same chemokines and exert synergistic pro-tumour or anti-tumour functions in the tumour microenvironment. Chemokines and cytokines affect tumour metastasis and prognosis and may be potential targets for treatment.