Differentiation of immature DCs into endothelial-like cells in human esophageal carcinoma tissue homogenates

Exploring the crosstalk between endothelial cells, immune cells, and immune checkpoints in the tumor microenvironment: new insights and therapeutic implications

The tumor microenvironment (TME) is a highly intricate milieu, comprising a multitude of components, including immune cells and stromal cells, that exert a profound influence on tumor initiation and progression. Within the TME, angiogenesis is predominantly orchestrated by endothelial cells (ECs), which foster the proliferation and metastasis of malignant cells. The interplay between tumor and immune cells with ECs is complex and can either bolster or hinder the immune system. Thus, a comprehensive understanding of the intricate crosstalk between ECs and immune cells is essential to advance the development of immunotherapeutic interventions. Despite recent progress, the underlying molecular mechanisms that govern the interplay between ECs and immune cells remain elusive. Nevertheless, the immunomodulatory function of ECs has emerged as a pivotal determinant of the immune response. In light of this, the study of the relationship between ECs and immune checkpoints has garnered considerable attention in the field of immunotherapy. By targeting specific molecular pathways and signaling molecules associated with ECs in the TME, novel immunotherapeutic strategies may be devised to enhance the efficacy of current treatments. In this vein, we sought to elucidate the relationship between ECs, immune cells, and immune checkpoints in the TME, with the ultimate goal of identifying novel therapeutic targets and charting new avenues for immunotherapy.

Tumor microenvironment-related dendritic cell deficiency: a target to enhance tumor immunotherapy

Dendritic cells (DCs), as specialized antigen-presenting cells, are essential for the initiation of specific T cell responses in innate antitumor immunity and, in certain cases, support humoral responses to inhibit tumor development. Mounting evidence suggests that the DC system displays a broad spectrum of dysfunctional status in the tumor microenvironment (TME), which ultimately affects antitumor immune responses. DC-based therapy can restore the function of DCs in the TME, thus showing a promising potential in tumor therapy. In this review, we provide an overview of the DC deficiency caused by various factors in the TME and discuss proposed strategies to reverse DC deficiency and the applications of novel combinatorial DC-based therapy for immune normalization of the tumor.

Metformin inhibits esophageal squamous cell carcinoma-induced angiogenesis by suppressing JAK/STAT3 signaling pathway

Although it has been known that the tumor microenvironment affects angiogenesis, the precise mechanism remains unclear. In this study, we simulated the microenvironment of human esophageal squamous cell carcinoma (ESCC) by tumor conditioned medium (TCM) to assess the influence on normal endothelial cells (NECs). We found that the TCM-induced NECs showed enhanced angiogenic properties, such as migration, invasion and tube formation. Moreover, the TCM-induced NECs expressed tumor endothelial cells (TECs) markers at higher levels, which indicated that TCM probably promoted tumor angiogenesis by coercing NECs to change toward TECs. The microarray gene expression analysis indicated that TCM induced great changes in the genome of NECs and altered many regulatory networks, especially c-MYC and JAK/STAT3 signaling pathway. More importantly, we investigated the anti-angiogenic effect of metformin, and found that metformin abrogated the ESCC microenvironment-induced transition of NECs toward TECs by inhibiting JAK/STAT3/c-MYC signaling pathway. Furthermore, we verified the anti-angiogenic activity of metformin in vivo by a human ESCC patient-derived xenograft (PDX) mouse model for the first time. Taken together, our research provides a novel mechanism for the anti-angiogenic effect of metformin, and sets an experimental basis for the development of new anti-angiogenic drugs by blocking the transition of NECs toward TECs, which possibly open new avenues for targeted treatment of cancer.

Follistatin-like protein 1 contributes to dendritic cell and T-lymphocyte activation in nasopharyngeal carcinoma patients by altering nuclear factor κb and Jun N-terminal kinase expression

Follistatin‐like protein 1 (FSTL1) is a newly characterized protein that can regulate the immune response in various ways. Dendritic cells (DCs) are central to immune regulation. In this study, we explored the impact of FSTL1 on DC activity in nasopharyngeal carcinoma (NPC) patients. The surface expression of CD40, CD86, and HLA‐DR on DCs was analyzed and showed significantly elevated expression levels, indicating DC maturity. After FSTL1 was added to DCs collected from NPC patients (n = 50), controls (n = 47), and healthy donors (n = 10), interferon γ secretion and T‐cell receptor expression in cytotoxic T lymphocytes were also investigated. In the experimental groups, the expression of the critical immune protein nuclear factor (NF)‐κb was upregulated, whereas Jun N‐terminal kinase (JNK) was downregulated. Our findings demonstrate that FSTL1 plays a critical role in immune regulation, enhancing the antigen presentation ability of DCs by up‐regulating NF‐κb expression and down‐regulating JNK expression.

Dendritic cells loading autologous tumor lysate promote tumor angiogenesis

Dendritic cells (DC) have been exploited for vaccination against cancer for years. DC loading autologous tumor lysate (ATL-DC) have been assessed in ongoing clinical trials, but frequently do not meet expectation. In this study, we found that mice immunized with ATL-DC induced less protective anti-tumor effect than immunized with DC alone. The percentage of CD8+ T cells and the lysis efficiency of CTLs to auto tumor cells in ATL-DC vaccination group was less than that of DC group. Moreover, vaccination of mice with ATL-DC also promoted tumor angiogenesis by analyzing the CD31 positive microvessel density and hemoglobin content of tumor specimens. Human umbilical vein endothelial cells (HUVEC) have been proved effective in the anti-angiogenesis immunity against cancer. However, in the following research we found that the anti-tumor effect was attenuated while immunized mice with HUVEC combined with ATL-DC (HUVEC + ATL-DC). Furthermore, immunized mice with HUVEC + ATL-DC profoundly increased the tumor angiogenesis by analyzing the microvessel density and hemoglobin content of tumor specimens. These data suggest that vaccination using ATL-DC antagonized HUVEC induced anti-angiogenesis effect. Our research for the first time indicated that ATL-DC have the potential to promote the process of tumor angiogenesis in vivo. As vaccines based on DC loading autologous tumor lysate have been used in clinical, this find warned that the safety of this kind of vaccine should be taken into consideration seriously.

Genome-wide analysis of the effect of esophageal squamous cell carcinoma on human umbilical vein endothelial cells

A large volume of data indicates that controlling tumor-associated angiogenesis is a promising therapy against cancer. However, angiogenesis is a complex process, little is known about the differential gene expression in the process of normal endothelial cell differentiation toward tumor vascular endothelial cells induced by tumor microenvironment. The aim of this study is to investigate the effect of tumor microenvironment simulated by the supernatant of esophageal squamous cancer cells (KYSE70) on normal endothelial cells (HUVECs) at the whole genome level. The gene expression profile was studied through gene ontology and signal pathway analysis. Compared with the normal HUVECs, a total of 3769 differentially expressed genes in induced HUVECs were detected, including 1609 upregulated genes and 2160 downregulated genes. Moreover, the microarray data analysis showed that 11 significant biological processes and 10 significant signaling pathways changed most, which are associated with angiogenesis and cell differentiation. According to the different expression levels in the microarrays and their functions, four differentially expressed genes involved in tumor angiogenesis and cell differentiation (IL6, VEGFA, S1PR1, TYMP) were selected and analyzed by qRT-PCR. The qRT-PCR results were consistent with the microarray data. Furthermore, we simulated the tumor microenvironment by human esophageal carcinoma tissue homogenate to investigate its effect on HUVECs, the qRT-PCR results indicated that the above genes were highly expressed in HUVECs after induction by esophageal carcinoma tissue homogenate. In conclusion, tumor microenvironment impact on normal endothelial cells differentiated toward tumor vascular endothelial cells, and the selected genes, which are associated with tumor angiogenesis, would be anti-angiogenesis targets against esophageal carcinoma.