Histological differentiation impacts the tumor immune microenvironment in gastric carcinoma: Relation to the immune cycle

Associations of mucinous differentiation and mucin expression with immune cell infiltration and prognosis in colorectal adenocarcinoma

BACKGROUND

The production of extracellular mucus and expression of mucins are commonly aberrant in colorectal cancer, yet their roles in tumour progression remain unclear.

METHODS

To investigate the potential influence of mucus on immune response and prognosis, we analysed mucinous differentiation (non-mucinous, 0%; mucinous component, 1-50%; mucinous, >50%) and its associations with immune cell densities (determined with three multiplex immunohistochemistry assays or conventional immunohistochemistry) and survival in 1049 colorectal cancer patients and a validation cohort of 771 patients. We also assessed expression patterns of transmembrane (MUC1, MUC4) and secreted (MUC2, MUC5AC and MUC6) mucins using immunohistochemistry.

RESULTS

Mucinous differentiation was associated with higher densities of CD14+HLADR- immature monocytic cells and M2-like macrophages in mismatch repair (MMR) proficient tumours, and lower T-cell densities in MMR-deficient tumours. Mucinous differentiation was not associated with cancer-specific survival in multivariable Cox regression models. Higher cytoplasmic MUC1 expression independently predicted worse cancer-specific survival (multivariable HR for high vs. negative to low expression, 2.14; 95% CI: 1.26-3.64). It was also associated with increased myeloid cell infiltration in MMR-proficient tumours.

CONCLUSIONS

Although mucinous differentiation did not independently predict survival, extracellular mucus and MUC1 expression could promote tumour progression through immunosuppression.

Defining the high-risk category of patients with cutaneous melanoma: a practical tool based on prognostic modeling

Introduction

Although most cutaneous melanoma (CM) in its early stages is treatable, the risk of recurrence remains high and there is a particular ambiguity on patients prognosis. This drives to identification of prognostic biomarkers for predicting CM recurrence to guide appropriate treatment in patients with localized melanoma.

Aim

This study aimed to develop a prognostic model for assessing the risk of recurrence in patients with CM, enabling prompt prognosis-driven further clinical decision-making for high-risk patients.

Materials and methods

This case-control study included 172 patients with CM recurrence (high-risk group) and 30 patients with stable remission (low-risk group) 3 years after primary diagnosis. The impact of sex, age at diagnosis, anatomical site, histological characteristics (the histological type, pathological stage, ulceration; the depth of invasion, mitotic rate, lymphovascular invasion, neurotropism, association with a nevus, tumor-infiltrating lymphocyte density, tumor regression and BRAF codon 600 mutation status) on CM recurrence was evaluated.

Results

Five independent variables, including nodal status, a high mitotic rate, Breslow thickness, lymphovascular invasion, perineural invasion and regression features were identified as the most significant. A 5-factor logistic regression model was developed to assess the risk of melanoma recurrence. The sensitivity and specificity of the model were 86.1% and 72.7%, respectively.

Conclusion

The developed model, which relies on routine histological features, allows the identification of individuals at high risk of CM recurrence to tailor their further management.

Comprehensive landscape of m6A regulator-related gene patterns and tumor microenvironment infiltration characterization in gastric cancer

The epigenetic regulation of N6-methyladenosine (m6A) has attracted considerable interest in tumor research, but the potential roles of m6A regulator-related genes, remain largely unknown within the context of gastric cancer (GC) and tumor microenvironment (TME). Here, a comprehensive strategy of data mining and computational biology utilizing multiple datasets based on 28 m6A regulators (including novel anti-readers) was employed to identify m6A regulator-related genes and patterns and elucidate their underlying mechanisms in GC. Subsequently, a scoring system was constructed to evaluate individual prognosis and immunotherapy response. Three distinct m6A regulator-related patterns were identified through the unsupervised clustering of 56 m6A regulator-related genes (all significantly associated with GC prognosis). TME characterization revealed that these patterns highly corresponded to immune-inflamed, immune-excluded, and immune-desert phenotypes, and their TME characteristics were highly consistent with different clinical outcomes and biological processes. Additionally, an m6A-related scoring system was developed to quantify the m6A modification pattern of individual samples. Low scores indicated high survival rates and high levels of immune activation, whereas high scores indicated stromal activation and tumor malignancy. Furthermore, the m6A-related scores were correlated with tumor mutation loads and various clinical traits, including molecular or histological subtypes and clinical stage or grade, and the score had predictive values across all digestive system tumors and even in all tumor types. Notably, a low score was linked to improved responses to anti-PD-1/L1 and anti-CTLA4 immunotherapy in three independent cohorts. This study has expanded the important role of m6A regulator-related genes in shaping TME diversity and clinical/biological traits of GC. The developed scoring system could help develop more effective immunotherapy strategies and personalized treatment guidance.

Diabetes Mellitus and Gastric Cancer: Correlation and Potential Mechanisms

This review summarizes the correlation between diabetes mellitus (DM) and gastric cancer (GC) from the perspectives of epidemiology, drug use, and potential mechanisms. The association between DM and GC is inconclusive, and the positive direction of the association reported in most published meta-analyses suggests that DM may be an independent risk factor for GC. Many clinical investigations have shown that people with DM and GC who undergo gastrectomy may have better glycemic control. The potential link between DM and GC may involve the interaction of multiple common risk factors, such as obesity, hyperglycemia and hyperinsulinemia, H. pylori infection, and the use of metformin. Although in vitro and in vivo data support that H. pylori infection status and metformin can influence GC risk in DM patients, there are conflicting results. Patient survival outcomes are influenced by multiple factors, so further research is needed to identify the patients who may benefit.

Histological Type, Cytotoxic T Cells and Macrophages in the Tumor Microenvironment Affect the PD-L1 Status of Gastric Cancer

Gastric cancer (GC) therapies include gastrectomy and chemoradiotherapy. The tumor immune microenvironment (TME) has implications for potential immunotherapy. We analyzed the expression of PD-L1, CD8, CTLA-4 and IFN-γ in the tumor and regional lymph node (LN) of patients with GC and compared it with clinical and pathological data. Paraffin blocks were collected from 97 patients undergoing gastrectomy/lymphadenectomy for GC. Double immunohistochemistry was performed for CD8 and PD-L1 and double immunofluorescence for CTLA-4 and IFN-γ. Statistical significance was set at p < 0.05. PD-L1 expression in tumor cells was associated with intestinal GC type (p = 0.046), the density of macrophages and CD8 + T cells (p < 0.001, both). The median number of CD8+ T cells was higher in PD-L1-positive than in -negative tumors. A cut-off of 28.5 CD8 + T cells in one high-magnification field predicted PD-L1-positive tumors (AUROC 0.797, sensitivity 74.2%, specificity 77.3%). IFN-γ expression in tumor cells was found in 37 GCs and was positively associated with CTLA4+ lymphocytes in the LN (p = 0.027) and CTLA4+/IFN-γ+ in tumors and the LN (all p < 0.001). The median overall survival (OS) was 17 months. In the group of deceased patients, IFN-γ expression in metastases correlated with lower OS (RHO = −0.314, p = 0.008). PD-L1 expression in tumor cells correlated with CD8 + T cells and macrophages in the TME and IFN-γ expression with suppressive CTLA4+/IFNγ+ immune cells in the TME and LN.

Cold atmospheric plasma: Novel opportunities for tumor microenvironment targeting

With mounting preclinical and clinical evidences on the prominent roles of the tumor microenvironment (TME) played during carcinogenesis, the TME has been recognized and used as an important onco-therapeutic target during the past decade. Delineating our current knowledge on TME components and their functionalities can help us recognize novel onco-therapeutic opportunities and establish treatment modalities towards desirable anti-cancer outcome. By identifying and focusing on primary cellular components in the TME, that is, tumor-infiltrating lymphocytes, tumor-associated macrophages, cancer-associated fibroblasts and mesenchymal stem cells, we decomposed their primary functionalities during carcinogenesis, categorized current therapeutic approaches utilizing traits of these components, and forecasted possible benefits that cold atmospheric plasma, a redox modulating tool with selectivity against cancer cells, may convey by targeting the TME. Our insights may open a novel therapeutic avenue for cancer control taking advantages of redox homeostasis and immunostasis.

Immune Microenvironment of Muscular-Invasive Urothelial Carcinoma: The Link to Tumor Immune Cycle and Prognosis

In this study, we investigated the relationship between the tumor immune microenvironment (TIME), histological differentiation and hypoxia in patients with muscular-invasive urothelial carcinomas (MIUC) after radical cystectomy. Forty-two cases of pT2-3N0M0 MIUCs underwent clinical, histological and immunohistochemical evaluation by counting CD8+, FOXP3+, CD68+, CD163+ cells and polymorphonuclear leukocytes (PMN) in intra-tumoral and peritumoral areas, assessing PD-L1 and GLUT1 expression for defining the impact of tumor immune contexture on patients’ outcomes. Five-year survival rates and overall survival were calculated. Most of the MIUCs demonstrated the immune-desert or immune-excluded TIME, reflecting altered mechanisms of T-cells’ activation or traffic into tumors. Tumor immune contexture was closely related to histological differentiation. CD8+ cells were scant in MIUCs with papillary and squamous differentiation, while basal-like or mesenchymal-like histological differentiation was associated with increased density of CD8+ cells. A high rate of PD-L1 expression (47.6%) was not related to immune cell infiltration. M2-macrophages predominated under CD8+ lymphocytes. The abundance of PMN and CD163+ macrophages in MIUCs was associated with high GLUT1 expression. CD8+, CD68+, FOXP3+ cells and PD-L1 status did not affect patients’ outcomes, while high CD163+ density and PMN infiltration were associated with the unfavorable outcome of patients with MIUC. These data drive the hypothesis that in MIUC, immune escape mechanisms are shifted towards the role of the innate immunity cells rather than CD8+ lymphocytes’ functioning.

Cancer Stem Cells and the Tumor Microenvironment in Gastric Cancer

Gastric cancer (GC) remains one of the leading causes of cancer-related death worldwide. Cancer stem cells (CSCs) might be responsible for tumor initiation, relapse, metastasis and treatment resistance of GC. The tumor microenvironment (TME) comprises tumor cells, immune cells, stromal cells and other extracellular components, which plays a pivotal role in tumor progression and therapy resistance. The properties of CSCs are regulated by cells and extracellular matrix components of the TME in some unique manners. This review will summarize current literature regarding the effects of CSCs and TME on the progression and therapy resistance of GC, while emphasizing the potential for developing successful anti-tumor therapy based on targeting the TME and CSCs.