Metabolic dysfunction and early-onset colorectal cancer - how macrophages build the bridge

Obesity and early-onset colorectal cancer risk: emerging clinical evidence and biological mechanisms

Early-onset colorectal cancer (EOCRC) is defined as diagnosed at younger than 50 years of age and indicates a health burden globally. Patients with EOCRC have distinct risk factors, clinical characteristics, and molecular pathogenesis compared with older patients with CRC. Further investigations have identified different roles of obesity between EOCRC and late-onset colorectal cancer (LOCRC). Most studies have focused on the clinical characteristics of obesity in EOCRC, therefore, the mechanism involved in the association between obesity and EOCRC remains inconclusive. This review further states that obesity affects the carcinogenesis of EOCRC as well as its development and progression, which may lead to obesity-related metabolic syndrome, intestinal dysbacteriosis, and intestinal inflammation.

Obesity and Inflammatory Factors in the Progression of Early-Onset Colorectal Cancer

Metabolic dysfunction associated with obesity leads to a chronic pro-inflammatory state with systemic effects, including the alteration of macrophage metabolism. Tumor-associated macrophages have been linked to the formation of cancer through the production of metabolites such as itaconate. Itaconate downregulates peroxisome proliferator-activated receptor gamma as a tumor-suppressing factor and upregulates anti-inflammatory cytokines in M2-like macrophages. Similarly, leptin and adiponectin also influence macrophage cytokine expression and contribute to the progression of colorectal cancer via changes in gene expression within the PI3K/AKT pathway. This pathway influences cell proliferation, differentiation, and tumorigenesis. This work provides a review of obesity-related hormones and inflammatory mechanisms leading to the development and progression of early-onset colorectal cancer (EOCRC). A literature search was performed using the PubMed and Cochrane databases to identify studies related to obesity and EOCRC, with keywords including 'EOCRC', 'obesity', 'obesity-related hormones', 'itaconate', 'adiponectin', 'leptin', 'M2a macrophage', and 'microbiome'. With this concept of pro-inflammatory markers contributing to EOCRC, increased use of chemo-preventative agents such as aspirin may have a protective effect. Elucidating this association between obesity-related, hormone/cytokine-driven inflammatory effects with EOCRC may help lead to new therapeutic targets in preventing and treating EOCRC.

Targeting Mitochondria for Cancer Treatment

There is an increasing accumulation of data on the exceptional importance of mitochondria in the occurrence and treatment of cancer, and in all lines of evidence for such participation, there are both energetic and non-bioenergetic functional features of mitochondria. This analytical review examines three specific features of adaptive mitochondrial changes in several malignant tumors. The first feature is characteristic of solid tumors, whose cells are forced to rebuild their energetics due to the absence of oxygen, namely, to activate the fumarate reductase pathway instead of the traditional succinate oxidase pathway that exists in aerobic conditions. For such a restructuring, the presence of a low-potential quinone is necessary, which cannot ensure the conventional conversion of succinate into fumarate but rather enables the reverse reaction, that is, the conversion of fumarate into succinate. In this scenario, complex I becomes the only generator of energy in mitochondria. The second feature is the increased proliferation in aggressive tumors of the so-called mitochondrial (peripheral) benzodiazepine receptor, also called translocator protein (TSPO) residing in the outer mitochondrial membrane, the function of which in oncogenic transformation stays mysterious. The third feature of tumor cells is the enhanced retention of certain molecules, in particular mitochondrially directed cations similar to rhodamine 123, which allows for the selective accumulation of anticancer drugs in mitochondria. These three features of mitochondria can be targets for the development of an anti-cancer strategy.

Anti-inflammatory mechanisms in cancer research: Characterization of a distinct M2-like macrophage model derived from the THP-1 cell line

AIMS

Macrophages play an essential role in cancer development. Tumor-associated macrophages (TAMs) have predominantly M2-like attributes that are associated with tumor progression and poor patient survival. Numerous methods have been reported for differentiating and polarizing macrophages in vitro, but there is no standardized and validated model for creating TAMs. Primary cells show varying cytokine responses depending on their origin and functional studies utilizing these cells may lack generalization and validity. A distinct cell line-derived TAM-like M2 subtype is required to investigate the mechanisms mediated by anti-inflammatory TAMs in vitro. Our previous work demonstrated a standardized protocol for creating an M2 subtype derived from a human THP-1 cell line. The cell expression profile, however, has not been validated. The aim of this study was to characterize and validate the TAM-like M2 subtype macrophage created based on our protocol to introduce them as a standardized model for cancer research.

METHODS AND RESULTS

Using qRT-PCR and ELISA, we demonstrated that proinflammatory, anti-inflammatory, and tumor-associated marker expression changed during THP-1-derived marcrophage development in vitro, mimicking a TAM-related profile (e.g., TNFα, IL-1β). The anti-inflammatory marker IL-8/CXCL8, however, is most highly expressed in young M0 macrophages. Flow cytometry showed increased expression of CD206 in the final TAM-like M2 macrophage. Single-cell RNA-sequencing analysis of primary human monocytes and colon cancer tissue macrophages demonstrated that cell line-derived M2 macrophages resembled a TAM-related gene profile.

CONCLUSIONS

The THP-1-derived M2 macrophage based on a standardized cell line model represents a distinct anti-inflammatory TAM-like phenotype with an M2a subtype profile. This model may provide a basis for in vitro investigation of functional mechanisms in a variety of anti-inflammatory settings, particularly colon cancer development.

Genome-scale modeling predicts metabolic differences between macrophage subtypes in colorectal cancer

Colorectal cancer (CRC) shows high incidence and mortality, partly due to the tumor microenvironment (TME), which is viewed as an active promoter of disease progression. Macrophages are among the most abundant cells in the TME. These immune cells are generally categorized as M1, with inflammatory and anti-cancer properties, or M2, which promote tumor proliferation and survival. Although the M1/M2 subclassification scheme is strongly influenced by metabolism, the metabolic divergence between the subtypes remains poorly understood. Therefore, we generated a suite of computational models that characterize the M1- and M2-specific metabolic states. Our models show key differences between the M1 and M2 metabolic networks and capabilities. We leverage the models to identify metabolic perturbations that cause the metabolic state of M2 macrophages to more closely resemble M1 cells. Overall, this work increases understanding of macrophage metabolism in CRC and elucidates strategies to promote the metabolic state of anti-tumor macrophages.

Innate Immune Cells in the Tumor Microenvironment of Liver Metastasis from Colorectal Cancer: Contribution to a Comprehensive Therapy

Colorectal cancer (CRC) is the third most prevalent type of cancer, and liver metastasis is the most common site of metastatic development. In the tumor microenvironment (TME), various innate immune cells are known to influence cancer progression and metastasis occurrence. CD274 (PD-L1) and CD206 (MRC1) are proteins that have been associated with poor prognosis and disease progression. We conducted a study on tumoral and non-tumoral biopsies from 47 patients with CRC liver metastasis, using flow cytometry to phenotypically characterize innate immune cells. Our findings showed an increase in the expression of CD274 on classical, intermediate, and non-classical monocytes when comparing tumor with non-tumor samples. Furthermore, tumor samples with a desmoplastic growth pattern exhibited a significantly decreased percentage of CD274- and CD206-positive cells in all monocyte populations compared to non-desmoplastic samples. We found a correlation between a lower expression of CD206 or CD274 on classical, intermediate, and non-classical monocytes and increased disease-free survival, which points to a better prognosis for these patients. In conclusion, our study has identified potential new targets and biomarkers that could be incorporated into a personalized medicine approach to enhance the outcome for colorectal cancer patients.

Itaconate: A Potent Macrophage Immunomodulator

With advances in immunometabolic studies, more and more evidence has shown that metabolic changes profoundly affect the immune function of macrophages. The tricarboxylic acid cycle is a central metabolic pathway of cells. Itaconate, a byproduct of the tricarboxylic acid cycle, is an emerging metabolic small molecule that regulates macrophage inflammation and has received much attention for its potent anti-inflammatory effects in recent years. Itaconate regulates macrophage function through multiple mechanisms and has demonstrated promising therapeutic potential in a variety of immune and inflammatory diseases. New progress in the mechanism of itaconate continues to be made, but it also implies complexity in its action and a need for a more comprehensive understanding of its role in macrophages. In this article, we review the primary mechanisms and current research progress of itaconate in regulating macrophage immune metabolism, hoping to provide new insights and directions for future research and disease treatment.

Role of tumor-associated macrophages in common digestive system malignant tumors

Many digestive system malignant tumors are characterized by high incidence and mortality rate. Increasing evidence has revealed that the tumor microenvironment (TME) is involved in cancer initiation and tumor progression. Tumor-associated macrophages (TAMs) are a predominant constituent of the TME, and participate in the regulation of various biological behaviors and influence the prognosis of digestive system cancer. TAMs can be mainly classified into the antitumor M1 phenotype and protumor M2 phenotype. The latter especially are crucial drivers of tumor invasion, growth, angiogenesis, metastasis, immunosuppression, and resistance to therapy. TAMs are of importance in the occurrence, development, diagnosis, prognosis, and treatment of common digestive system malignant tumors. In this review, we summarize the role of TAMs in common digestive system malignant tumors, including esophageal, gastric, colorectal, pancreatic and liver cancers. How TAMs promote the development of tumors, and how they act as potential therapeutic targets and their clinical applications are also described.

Dioscin modulates macrophages polarization and MDSCs differentiation to inhibit tumorigenesis of colitis-associated colorectal cancer

It has been reported that colitis is one of risk factors in colorectal cancer (CRC). Intervention of intestinal inflammation and in the early stage of tumorigenesis is of great significance to control the incidence and mortality of CRC. In recent years, natural active products of traditional Chinese medicine have been confirmed that they had made great progress in disease prevention. Here, we showed that Dioscin, a natural active product of Dioscorea nipponica Makino, inhibited initiation and tumorigenesis of AOM/DSS-induced colitis-associated colon cancer (CAC), including alleviating colonic inflammation, improving intestinal barrier function and decreasing tumor burden. In addition, we also explored the immunoregulatory effect of Dioscin on mice. The results showed that Dioscin modulated M1/M2 macrophages phenotype in spleen and decreased monocytic myeloid-derived suppressor cells (M-MDSCs) population in blood and spleen of mice. The in vitro assay demonstrated that Dioscin promoted M1 as well as inhibited M2 macrophages phenotype in LPS- or IL-4-induced bone marrow-derived macrophages (BMDMs) model. Based on the plasticity of MDSCs and its ability to differentiate into M1/M2 macrophages, we here found that Dioscin increased M1- and decreased M2-like phenotype during the process of MDSCs differentiation in vitro, suggesting Dioscin promoted MDSCs differentiate into M1 as well as inhibited its differentiation into M2 macrophages. Taken together, our study indicated that Dioscin had the inhibitory effect on the initial of tumorigenesis at early stage of CAC via the ant-inflammatory effect, which provided a natural active candidate for effective prevention of CAC.

Obesity hormones and itaconate mediating inflammation in human colon cancer cells - Another lead to early-onset colon cancer?

Background

Chronic inflammation is a key feature of obesity and a hallmark of colon cancer (CC). The obesity-related hormones leptin and adiponectin alter inflammatory gene profiles in cancer, but their specific role in CC is unclear. We have previously studied the effects of leptin and the macrophage-specific mediator itaconate on M2-like macrophages. This current study evaluates their effects on CC cells.

Methods

HT-29 CC cells (derived from a young patient, stage III CC) were treated with either leptin, adiponectin, 4-octyl itaconate (OI) or dimethyl itaconate (DI). Gene expression after treatment was analyzed at four time points (3, 6, 18, and 24 h).

Results

CCL22 was upregulated after treatment with adiponectin (at 18 h [FC 16.3, p < 0.001]). IL-8 expression increased following both adiponectin (at 3 h [FC 68.1, p < 0.001]) and leptin treatments (at 6 h [FC 7.3, p < 0.001]), while OI induced downregulation of IL-8 (at 24 h [FC -5.0, p < 0.001]). CXCL10 was upregulated after adiponectin treatment (at 6 h [FC 3.0, p = 0.025]) and downregulated by both OI and DI at 24 h, respectively (OI [FC -10.0, p < 0.001]; DI [FC -10.0, p < 0.001]). IL-1β was upregulated after adiponectin treatment (at 3 h [FC 10.6, p < 0.001]) and downregulated by DI (at 24 h [FC -5.0, p < 0.001]). TNF-α expression was induced following adiponectin (at 6 h [FC 110.7, p < 0.001]), leptin (at 18 h [FC 5.8, p = 0.027]) and OI (at 3 h [FC 91.1, p = 0.001]). PPARγ was affected by both OI (at 3 h [FC 10.1, p = 0.031], at 24 h [FC -10.0, p = 0.031]) and DI (at 18 h [FC -1.7, p = 0.033]).

Conclusions

Obesity hormones directly affect inflammatory gene expression in HT29 CC cells, potentially enhancing cancer progression. Itaconate affects the prognostic marker PPARγ in HT29 CC cells. Leptin, adiponectin and itaconate may represent a link between obesity and CC.

Comparison of some biochemical markers between early‐onset and late‐onset colorectal precancerous lesions: A single‐center retrospective study

Objective

Given that the onset of diseases including colorectal cancer precursors is affecting younger individuals and that obesity is an important risk factor for early‐onset, we conducted a study to explore the biochemical profile of differences in serum between early‐onset patients and late‐onset colorectal precancerous lesions.

Methods

A total of 1447 patients, including 469 early‐onset patients and 978 late‐onset patients, were enrolled from the First Affiliated Hospital of Nanchang University (FAHNU), of which there were 311 sessile serrated adenoma/polyps (SSA/P) and 1136 normal adenomas. The distribution of the included categorical variables was compared via Pearson's chi‐squared test, whereas continuous variables were compared by using the nonparametric Kruskal–Wallis test and anova.

Results

Compared with late‐onset patients, the levels of total bilirubin and HDL‐C were lower (p < 0.05), whereas triglyceride and uric acid levels were higher, in early‐onset patients. Interestingly, in the subgroup analysis, triglyceride and uric acid levels remained at higher levels, whereas HDL‐C remained at lower levels, in early‐onset patients than in late‐onset patients. Other characteristics, such as LDL‐C, drinking, γ‐GT, and the N/L ratio, were similar between the two groups. An additional analysis of the association of tumor size with markers showed that lower levels of HDL‐C and higher levels of uric acid were associated with increased tumor size (p < 0.05).

Conclusions

Early‐onset CRC precursor cases exhibit higher levels of triglycerides and lower levels of HDL‐C than late‐onset cases. Additionally, levels of HDL‐C are negatively associated with tumor size, whereas uric acid was positively correlated with tumor size.

Additive Effect of CD73 Inhibitor in Colorectal Cancer Treatment With CDK4/6 Inhibitor Through Regulation of PD-L1

BACKGROUND & AIMS

Although cancer immunotherapies are effective for advanced-stage cancers, there are no clinically approved immunotherapies for colon cancers (CRCs). Therefore, there is a high demand for the development of novel therapies. Extracellular adenosine-mediated signaling is considered a promising target for advanced-stage cancers that are nonresponsive to programmed death 1 (PD-1)-/programmed death-ligand 1 (PD-L1)-targeted immunotherapies. In this study, we aimed to elucidate novel tumorigenic mechanisms of extracellular adenosine.

METHODS

To investigate the effects of extracellular adenosine on tumor-associated macrophages, peripheral blood-derived human macrophages were treated with adenosine and analyzed using flow cytometry and Western blot. Changes in adenosine-treated macrophages were further assessed using multi-omics analysis, including total RNA sequencing and proteomics. Colon cancer mouse models were used to measure the therapeutic efficacy of AB680 and palbociclib. We also used tissue microarrays of patients with CRC, to evaluate their clinical relevance.

RESULTS

Extracellular adenosine-mediated reduction of cyclin D1 (CCND1) was found to be critical for the regulation of immune checkpoint molecules and PD-L1 levels in human macrophages, indicating that post-translational modification of PD-L1 is affected by adenosine. A potent CD73 selective inhibitor, AB680, reversed the effects of adenosine on CCND1 and PD-L1. This result strongly suggests that AB680 is a combinatory therapeutic option to overcome the undesired side effects of the cyclin-dependent kinase 4/6 inhibitor, palbociclib, which increases PD-L1 expression in tumors. Because palbociclib is undergoing clinical trials for metastatic CRC in combination with cetuximab (clinical trial number: NCT03446157), we validated that the combination of AB680 and palbociclib significantly improved anti-tumor efficacy in CRC animal models, thereby highlighting it as a novel immunotherapeutic strategy. We further assessed whether the level of CCND1 in tumor-associated macrophages was indeed reduced in tumor sections obtained from patients with CRC, for evaluating the clinical relevance of this strategy.

CONCLUSIONS

In this study, we demonstrated that a novel combination therapy of AB680 and palbociclib may be advantageous for the treatment of CRC.

Pan-Immune-Inflammation Value: A New Prognostic Index in Operative Breast Cancer

Background

To build a predictive scoring model based on simple immune and inflammatory parameters to predict postoperative survival in patients with breast cancer.

Methods

We used a brand-new immuno-inflammatory index-pan-immune-inflammation value (PIV)-to retrospectively evaluate the relationship between PIV and overall survival (OS), and based on the results of Cox regression analysis, we established a simple scoring prediction model based on several independent prognostic parameters. The predictive accuracy of the model was evaluated and independently validated.

Results

A total of 1,312 patients were included for analysis. PIV was calculated as follows: neutrophil count (10⁹/L) × platelet count (10⁹/L) × monocyte count (10⁹/L)/lymphocyte count (10⁹/L). According to the best cutoff value of PIV, we divided the patients into two different subgroups, high PIV (PIV > 310.2) and low PIV (PIV ≤ 310.2), associated with significantly different survival outcomes (3-year OS, 80.26% vs. 86.29%, respectively; 5-year OS, 62.5% vs. 71.55%, respectively). Six independent prognostic factors were identified and used to build the scoring system, which performed well with a concordance index (C-index) of 0.759 (95% CI: 0.715-0.802); the calibration plot showed good calibration.

Conclusions

We have established and verified a simple scoring system for predicting prognosis, which can predict the survival of patients with operable breast cancer. This system can help clinicians implement targeted and individualized treatment strategies.

Itaconate and leptin affecting PPARγ in M2 macrophages: A potential link to early-onset colorectal cancer

BACKGROUND

Along with the rising incidence of obesity, there has been an increase in patients diagnosed with early-onset colorectal cancer (<50 years old). In colorectal cancer, worse patient survival is associated with certain cytokine expression and downregulation of peroxisome proliferator activated receptor gamma expression. The effects of the obesity hormone leptin and macrophage-specific metabolite itaconate on these mechanisms are poorly understood. We investigated their impact on peroxisome proliferator activated receptor gamma and macrophage cytokine expression in vitro.

METHODS

M2-like macrophages were treated with either leptin, 4-octyl itaconate, or dimethyl itaconate in a dose- and time-dependent manner. Gene expression after treatment with 4 doses (D1-4) of each compound was analyzed at 4 time points (3, 6, 18, and 24 hours).

RESULTS

Peroxisome proliferator activated receptor gamma was downregulated after 4-octyl itaconate treatment at 18 hours (FC -32.67, P ≤ .001). Interleukin-8 was upregulated after leptin and dimethyl itaconate treatment at 6 hours (FC 26.35 at D4, P ≤ .001, and FC 23.26 at D3, P = .006). Dimethyl itaconate upregulated IL-1β at 24 hours (FC 18.00 at D4, P ≤ .001). Tumor necrosis factor-α showed maximum downregulation after 4-octyl itaconate at 18 hours (FC -103.25 at D4, P ≤ .001).

CONCLUSIONS

Itaconate downregulates peroxisome proliferator activated receptor gamma as a tumor-suppressing factor and upregulates anti-inflammatory cytokines in M2-like macrophages. Itaconate provides a link between obesity and colorectal cancer and may be a key regulator in early-onset colorectal cancer.

Early-Onset Colorectal Cancer in Patients under 50 Years of Age: Demographics, Disease Characteristics, and Survival

INTRODUCTION

Incidence of early-onset colorectal cancer (EO-CRC) is increasing in younger demographics. This study analyzes disease-specific survival in individuals under 50 years of age.

METHODS

Patients with colorectal malignancy were identified in the Surveillance Epidemiology and End Results (SEER) database from 2004 to 2015. Cases were categorized into typically screened (age 50-79 years) and non-typically screened (age 20-49 years) cohorts, as well as by decade. Kaplan-Meier curves and Cox proportional hazard models were used to study survival.

RESULTS

A total of 240,772 patients with colorectal cancer were analyzed. Average annual percent change in incidence was -0.24% among typically screened patients and +1.12% among patients with EO-CRC. Patients with EO-CRC more frequently presented with distal tumors (70.6% vs. 57.6%, P < .001) and advanced tumor stage (61.3% vs. 48.6%, P < .001). Patients aged 50 and over had comparable 5 year disease-specific survival to younger patients (68.2% vs. 66.4%, P = .31); however, patients in the 3rd, 4th, and 8th decade of life had particularly low survival rates (59.0% vs. 65.8% vs. 65.8%, logrank P < .001). Patients aged 20-29 years had the most increased risk of cause-specific mortality on univariable Cox regression analysis [HR 1.43, 95% CI 1.31-1.56; P < .001], although this was not significant on multivariable analysis [HR 1.06, 95% CI 0.97-1.15; P = .201]. Male sex, older age, advanced stage, rectal and/or cecal primary, and earlier year of diagnosis were independently associated with increased mortality.

CONCLUSION

Patients with EO-CRC are diagnosed at a later stage and have lower disease-specific survival than those in typically screened cohorts. Additional studies on tumor biology and surveillance strategies are needed to improve outcomes in this population.

Myeloid-Derived Suppressor Cells in Immune Microenvironment Promote Progression of Esophagogastric Junction Adenocarcinoma

Adenocarcinoma of the esophagogastric junction (AEG) is a fatal disease. Accumulating evidence indicates that, for a comprehensive understanding of AEG, studies should be conducted not only to investigate tumor cells, but also the tumor microenvironment (TME). In this study, we collected AEG patient data from The Cancer Genome Atlas, and used the CIBERSORT algorithm to analyze tumor-infiltrating immune cell profiles. The levels of CD8⁺ T cells and M0 and M2 macrophages were relatively high in AEG tissues. M2 macrophages were abundant in G3 tumors, and neutrophils were associated with poor prognosis. Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immunosuppressive cells which share a similar origin to neutrophils and macrophages. We further analyzed the levels of MDSCs in AEG patients and healthy donors (HD) using flow cytometry. MDSC levels were elevated at tumor sites, with polymorphonuclear MDSCs (PMN-MDSCs) being the predominant subtype. Circulating MDSCs partly represented cells at the tumor site. We observed that PMN-MDSC levels at tumor sites were positively correlated with advanced staging, low grade, lymph node metastasis, and HER2⁻ status. Immunohistochemistry and immunofluorescence analyses indicated that activation of the STAT3 and NF-κB pathways in MDSCs may be a potential mechanism for cancer progression. Our studies provided a comprehensive perspective involving tumor-infiltrating immune cells, and detailed insights into the proportion of MDSCs in AEG and their clinical significance. Together, these findings may improve our current understanding of cancer progression involving tumor-infiltrating immune cells in the TME.