Targeting the Microenvironment in Esophageal Cancer

Lysophosphatidic acid promotes ESCC progression by increasing the level of CCL2 secreted by esophageal epithelial cells

BACKGROUND

Lysophosphatidic acid (LPA) is a small bioactive lipid which acts as a potent regulator in various tumor progressions through six G-protein-coupled receptors (LPA1-LPA6). Our previous study demonstrated that the LPA-producing enzyme, autotaxin (ATX), was upregulated in esophageal squamous cell carcinoma (ESCC) and ATX high expression levels indicated a poor prognosis. Esophageal squamous cell carcinoma is a type of malignant tumor which originates from epithelial cells. Its progression can be affected by the interaction between cancer cells and normal cells. However, the impact of LPA on the interaction between esophageal epithelial cells and cancer cells in the development of ESCC remains uncertain.

METHODS

MTS and Edu assays were performed to determine ESCC cell proliferation in culture medium (CM) derived from LPA-stimulated esophageal epithelial cells (Het-1a). A wound healing assay, transwell migration and an invasion assay were performed to assess the metastatic ability of ESCC cells. Cytokine array analysis was conducted to detect the differentially secreted cytokines in CM. The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were utilized to uncover the pathways and cytokines that are influenced by LPA in ESCC. Immunohistochemical staining was employed to measure the expression of ATX and CCL2 in early-stage ESCC. Quantitative real-time PCR, western blot, enzyme-linked immunosorbent assay and an antibody neutralization assay were employed to measure the mechanism of LPA-mediated communication between epithelial cells and cancer cells.

RESULTS

Functional experiments showed that exposing ESCC cancer cells to CM from LPA-treated Het-1a results in promoting proliferation, migration, invasion and epithelial-mesenchymal transition processes. Using cytokine array analysis, we discovered that LPA triggers the release of multiple cytokines from epithelial cells. After screening of the TCGA and GEO databases, CCL2 was identified and found to be correlated with ATX expression in ESCC. Furthermore, CCL2 levels in both mRNA expression and secretion were observed to be upregulated in epithelial cells upon stimulation with LPA. Blocking CCL2 effectively reduced the pro-migration influence of CM derived from LPA-treated Het-1a. Mechanism studies have demonstrated that LPA activated the NF-κB signaling pathway through LPA1/3, ultimately causing an increase in CCL2 expression and secretion in Het-1a.

CONCLUSIONS

Our findings, taken together, demonstrate that CM from LPA-treated esophageal epithelial cells plays a significant role in promoting the progression of ESCC, with CCL2 acting as the primary regulator.

Advancements in the research of immune checkpoint inhibitors for the treatment of advanced esophageal squamous cell carcinoma

Esophageal cancer (EC) has a high mortality rate and poor prognosis. Most patients are diagnosed at an advanced stage or with distant metastasis, making surgery impossible. Traditional curative radiotherapy and chemotherapy have limited efficacy. In recent years, with the development of clinical trials, immune checkpoint inhibitors (ICIs) have shown promising results in treating advanced and metastatic esophageal squamous cell carcinoma (ESCC) patients. ICIs have gradually become a primary therapeutic approach for EC. This review summarizes and provides an overview of the current research status and progress of ICIs in the treatment of advanced ESCC patients.

Mechanisms of tumor immunosuppressive microenvironment formation in esophageal cancer

As a highly invasive malignancy, esophageal cancer (EC) is a global health issue, and was the eighth most prevalent cancer and the sixth leading cause of cancer-related death worldwide in 2020. Due to its highly immunogenic nature, emer-ging immunotherapy approaches, such as immune checkpoint blockade, have demonstrated promising efficacy in treating EC; however, certain limitations and challenges still exist. In addition, tumors may exhibit primary or acquired resistance to immunotherapy in the tumor immune microenvironment (TIME); thus, understanding the TIME is urgent and crucial, especially given the im-portance of an immunosuppressive microenvironment in tumor progression. The aim of this review was to better elucidate the mechanisms of the suppressive TIME, including cell infiltration, immune cell subsets, cytokines and signaling pathways in the tumor microenvironment of EC patients, as well as the downregulated expression of major histocompatibility complex molecules in tumor cells, to obtain a better understanding of the differences in EC patient responses to immunotherapeutic strategies and accurately predict the efficacy of immunotherapies. Therefore, personalized treatments could be developed to maximize the advantages of immunotherapy.

Sitravatinib combined with PD-1 blockade enhances cytotoxic T-cell infiltration by M2 to M1 tumor macrophage repolarization in esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) is a leading cause of cancer-related mortality. Sitravatinib is a novel multi-gene tyrosine kinase inhibitor (TKI) that targets tumor-associated macrophage (TAM) receptors, VEGF, PDGF and c-Kit. Currently, sitravatinib is actively being studied in clinical trials across solid tumors and other TKIs have shown efficacy in combination with immune checkpoint inhibitors (ICI) in cancer models. In this study, we investigated the anti-tumor activity of sitravatinib alone and in combination with PD-1 blockade in an EAC rat model. Treatment response was evaluated by mortality, pre- and post-treatment MRI, gene expression, immunofluorescence and immunohistochemistry. Our results demonstrated adequate safety and significant tumor shrinkage in animals treated with sitravatinib, and more profoundly, sitravatinib and PD-1 inhibitor, AUNP-12 (P < 0.01). Suppression of TAM receptors resulted in increased gene expression of pro-inflammatory cytokines and decreased expression of anti-inflammatory cytokines, enhanced infiltration of CD8+ T cells, and M2 to M1 macrophage phenotype repolarization in the tumor microenvironment of treated animals (P < 0.01). Moreover, endpoint immunohistochemistry staining corroborated the anti-tumor activity by downregulation of Ki67 and upregulation of Caspase-3 in the treated animals. Additionally, pretreatment gene expression of TAM receptors and PD-L1 were significantly higher in major responders compared with the non-responders, in animals that received sitravatinib and AUNP-12 (P < 0.02), confirming that TAM suppression enhances the efficacy of PD-1 blockade. In conclusion, this study proposes a promising immunomodulatory strategy using a multi-gene TKI to overcome developed resistance to an ICI in EAC, establishing rationale for future clinical development.

DNMT1-mediated epigenetic suppression of FBXO32 expression promoting cyclin dependent kinase 9 (CDK9) survival and esophageal cancer cell growth

Esophageal cancer (EC) is a common and serious form of cancer, and while DNA methyltransferase-1 (DNMT1) promotes DNA methylation and carcinogenesis, the role of F-box protein 32 (FBXO32) in EC and its regulation by DNMT1-mediated methylation is still unclear. FBXO32 expression was examined in EC cells with high DNMT1 expression using GSE163735 dataset. RT-qPCR assessed FBXO32 expression in normal and EC cells, and impact of higher FBXO32 expression on cell proliferation, migration, and invasion was evaluated, along with EMT-related proteins. The xenograft model established by injecting EC cells transfected with FBXO32 was used to evaluate tumor growth, apoptosis, and tumor cells proliferation and metastasis. Chromatin immunoprecipitation (ChIP) assay was employed to study the interaction between DNMT1 and FBXO32. HitPredict, co-immunoprecipitation (Co-IP), and Glutathione-S-transferase (GST) pulldown assay analyzed the interaction between FBXO32 and cyclin dependent kinase 9 (CDK9). Finally, the ubiquitination assay identified CDK9 ubiquitination, and its half-life was measured using cycloheximide and confirmed through western blotting. DNMT1 negatively correlated with FBXO32 expression in esophageal cells. High FBXO32 expression was associated with better overall survival in patients. Knockdown of DNMT1 in EC cells increased FBXO32 expression and suppressed malignant phenotypes. FBXO32 repressed EC tumor growth and metastasis in mice. Enrichment of DNMT1 in FBXO32 promoter region led to increased DNA methylation and reduced transcription. Mechanistically, FBXO32 degraded CDK9 through promoting its ubiquitination.

Advancing Esophageal Cancer Treatment: Immunotherapy in Neoadjuvant and Adjuvant Settings

Locally advanced esophageal cancer (LAEC) poses a significant and persistent challenge in terms of effective treatment. Traditionally, the primary strategy for managing LAEC has involved concurrent neoadjuvant chemoradiation followed by surgery. However, achieving a pathologic complete response (pCR) has proven to be inconsistent, and despite treatment, roughly half of patients experience locoregional recurrence or metastasis. Consequently, there has been a paradigm shift towards exploring the potential of immunotherapy in reshaping the landscape of LAEC management. Recent research has particularly focused on immune checkpoint inhibitors, investigating their application in both neoadjuvant and adjuvant settings. These inhibitors, designed to block specific proteins in immune cells, are meant to enhance the immune system's ability to target and combat cancer cells. Emerging evidence from these studies suggests the possibility of a mortality benefit, indicating that immunotherapy may contribute to improved overall survival rates for individuals grappling with esophageal cancer. This manuscript aims to meticulously review the existing literature surrounding neoadjuvant and adjuvant immunotherapy in the context of LAEC management. The intention is to thoroughly examine the methodologies and findings of relevant studies, providing a comprehensive synthesis of the current understanding of the impact of immunotherapy on esophageal cancer.

Navigating Tumour Microenvironment and Wnt Signalling Crosstalk: Implications for Advanced Cancer Therapeutics

Cancer therapeutics face significant challenges due to drug resistance and tumour recurrence. The tumour microenvironment (TME) is a crucial contributor and essential hallmark of cancer. It encompasses various components surrounding the tumour, including intercellular elements, immune system cells, the vascular system, stem cells, and extracellular matrices, all of which play critical roles in tumour progression, epithelial-mesenchymal transition, metastasis, drug resistance, and relapse. These components interact with multiple signalling pathways, positively or negatively influencing cell growth. Abnormal regulation of the Wnt signalling pathway has been observed in tumorigenesis and contributes to tumour growth. A comprehensive understanding and characterisation of how different cells within the TME communicate through signalling pathways is vital. This review aims to explore the intricate and dynamic interactions, expressions, and alterations of TME components and the Wnt signalling pathway, offering valuable insights into the development of therapeutic applications.

Development and validation of a prognostic model for esophageal cancer patients with liver metastasis: a cohort study based on surveillance, epidemiology, and end results database

PURPOSE

Our objective is to examine the independent prognostic risk factors for patients with Esophageal Cancer with Liver Metastasis (ECLM) and to develop a predictive model.

METHODS

In this study, clinical data were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Cox regression analysis was employed to identify independent prognostic factors and construct nomograms based on the results of multivariate regression. The predictive performance of the nomograms was assessed using several methods, including the consistency index (C-index), calibration curve, time-dependent receiver-operating characteristic curve (ROC), and decision curve analysis (DCA). Additionally, Kaplan-Meier survival curves were generated to demonstrate the variation in overall survival between groups.

RESULTS

A total of 1163 ECLM patients were included in the study. Multivariate Cox analysis revealed that age, tumor differentiation grade, bone metastasis, therapy, and income were independently associated with overall survival (OS) in the training set. Subsequently, a prognostic nomogram was constructed based on these independent predictors. The C-index values were 0.739 and 0.715 in the training and validation sets, respectively. The area under the curve (AUC) values at 0.5, 1, and 2 years were all higher than 0.700. Calibration curves indicated that the nomogram accurately predicted OS. Decision curve analysis (DCA) showed moderately positive net benefits. Kaplan-Meier survival curves demonstrated significant differences in survival between high- and low-risk groups, which were divided based on the nomogram risk score.

CONCLUSIONS

The nomogram we developed for ECLM patients has demonstrated good predictive capability, allowing clinicians to accurately evaluate patient prognosis and identify those at high risk, thereby facilitating the development of personalized treatment plans.

Experimental and Computational Studies Reveal Novel Interaction of Lymphocytes Antigen 6K to TGF-β Receptor Complex

TGF-β signaling promotes migration, invasion, and distant colonization of cancer cells in advanced metastatic cancers. TGF-β signaling suppresses the anti-tumor immune response in a tumor microenvironment, allowing sustained tumor growth. TGF-β plays an important role in normal physiology; thus it is no surprise that the clinical development of effective and safe TGF-β inhibitors has been hampered due to their high toxicity. We discovered that increased expression of LY6K in cancer cells led to increased TGF-β signaling and that inhibition of LY6K could lead to reduced TGF-β signaling and reduced in vivo tumor growth. LY6K is a highly cancer-specific protein, and it is not expressed in normal organs except in the testes. Thus, LY6K is a valid target for developing therapeutic strategies to inhibit TGF-β signaling in cancer cells. We employed in vitro pull-down assays and molecular dynamics simulations to understand the structural determinants of the TGF-β receptor complex with LY6K. This combined approach allowed us to identify the critical residues and dynamics of the LY6K interaction with the TGF-β receptor complex. These data are critical in designing novel drugs for the inhibition of TGF-β in LY6K expressing cancer, induction of anti-tumor immune response, and inhibition of tumor growth and metastatic spread.

Visfatin upregulates VEGF-C expression and lymphangiogenesis in esophageal cancer by activating MEK1/2-ERK and NF-κB signaling

Lymph node metastasis is a recognized prognostic factor in esophageal cancer. Adipokines, including visfatin, and the molecule vascular endothelial growth factor (VEGF)-C, are implicated in lymphangiogenesis, but whether any association exists between esophageal cancer, adipokines and VEGF-C is unknown. We examined the relevance of adipokines and VEGF-C in esophageal squamous cell carcinoma (ESCC) in the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. We found significantly higher levels of visfatin and VEGF-C expression in esophageal cancer tissue than in normal tissue. Immunohistochemistry (IHC) staining identified that higher levels of visfatin and VEGF-C expression were correlated with advanced stage ESCC. Visfatin treatment of ESCC cell lines upregulated VEGF-C expression and VEGF-C-dependent lymphangiogenesis in lymphatic endothelial cells. Visfatin induced increases in VEGF-C expression by activating the mitogen-activated protein kinase kinases1/2-extracellular signal-regulated kinase (MEK1/2-ERK) and Nuclear Factor Kappa B (NF-κB) signaling cascades. Transfecting ESCC cells with MEK1/2-ERK and NF-κB inhibitors (PD98059, FR180204, PDTC, and TPCK) and siRNAs inhibited visfatin-induced increases in VEGF-C expression. It appears that visfatin and VEGF-C are promising therapeutic targets in the inhibition of lymphangiogenesis in esophageal cancer.

Development and validation of a nomogram for patients with stage II/III gastric adenocarcinoma after radical surgery

BACKGROUND

We aimed to construct nomograms based on clinicopathological features and routine preoperative hematological indices to predict cancer-specific survival (CSS) and disease-free survival (DFS) in patients with stage II/III gastric adenocarcinoma (GA) after radical resection.

METHODS

We retrospectively analyzed 468 patients with stage II/III GA after curative gastrectomy between 2012 and 2018; 70% of the patients were randomly assigned to the training set (n = 327) and the rest were assigned to the validation set (n = 141). The nomogram was constructed from independent predictors derived from the Cox regression in the training set. Using the consistency index, the calibration and the time-dependent receiver operating characteristic curves were used to evaluate the accuracy of the nomogram. Decision curve analysis was used to assess the value of the model in clinical applications. Patients were further divided into low- and high-risk groups based on the nomogram risk score.

RESULTS

Multivariate Cox model identified depth of invasion, lymph node invasion, tumor differentiation, adjuvant chemotherapy, CA724, and platelet-albumin ratio as covariates associated with CSS and DFS. CA199 is a risk factor unique to CSS. The nomogram constructed using the results of the multivariate analysis showed high accuracy with a consistency index of 0.771 (CSS) and 0.771 (DFS). Moreover, the area under the curve values for the 3-and 5-year CSS were 0.868 and 0.918, and the corresponding values for DFS were 0.872 and 0.919, respectively. The nomogram had a greater clinical benefit than the TNM staging system. High-risk patients based on the nomogram had a worse prognosis than low-risk patients.

CONCLUSION

The prognostic nomogram for patients with stage II/III GA after radical gastrectomy established in this study has a good predictive ability, which is helpful for doctors to accurately evaluate the prognosis of patients to make more reasonable treatment plans.

MAIP1-Related Tumor Immune Infiltration: As a Potential Prognostic Biomarker for Esophageal Cancer

Background

Esophageal cancer (EC), a common malignant tumor of digestive tract, is also one of the most deadly cancers. Accumulating studies have shown that the initiating and progressing multiple human diseases were closely related to the expression of MAIP. However, the specific roles and mechanisms of MAIP1 in EC remain incompletely defined.

Purpose

This study aims to determine the clinical significance of MAIP1 in EC and explores its potential molecular mechanisms regulating tumor immune infiltration.

Methods

We obtained RNA-seq datasets and corresponding clinical data for EC patients from the Cancer Genome Atlas (TCGA) database via the UCSC Xena browser to extract MAIP1 expression and plot survival curves to determine their prognosis. Based on the differential expression of MAIP1, EC patients were divided into high and low group to investigate the mechanism of MAIP1 in EC. In addition, the single sample gene set enrichment analysis (ssGSEA) quantified the expression of various immune cell signature marker genes and assessed the degree of immune infiltration in EC.

Results

In the TCGA-EC cohort, the overexpression of MAIP1 was observed in tumor tissues compared to normal tissues (p = 0.0038). Overall survival analysis showed that EC patients with the overexpression of MAIP1 presented a lower overall survival and worse prognosis (p = 0.004). Enrichment analysis revealed that the differential genes (DEGs) between high and low group are involved in biological functions such as extracellular matrix and organization extracellular structure. The results of ssGSEA showed that DCs, iDCs, macrophages, mast cells, and NK cells were significantly different in MAIP1^high and MAIP1^low groups, and all showed high expression in the MAIP1^low group.

Conclusion

We proposed that MAIP1 overexpression was associated with poor prognosis and tumor immune infiltration in EC. At present, there are few MAIP1-related tumor immune infiltration studies in EC, and further investigation is needed.

The Role of Tumor Microenvironment in Invasion and Metastasis of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers in the world, with a high rate of morbidity. The invasion and metastasis of ESCC is the main reason for high mortality. More and more evidence suggests that metastasized cancer cells require cellular elements that contribute to ESCC tumor microenvironment (TME) formation. TME contains many immune cells and stromal components, which are critical to epithelial–mesenchymal transition, immune escape, angiogenesis/lymphangiogenesis, metastasis niche formation, and invasion/metastasis. In this review, we will focus on the mechanism of different microenvironment cellular elements in ESCC invasion and metastasis and discuss recent therapeutic attempts to restore the tumor-suppressing function of cells within the TME. It will represent the whole picture of TME in the metastasis and invasion process of ESCC.

IGFBP7 remodels the tumor microenvironment of esophageal squamous cell carcinoma by activating the TGFβ1/SMAD signaling pathway

Esophageal squamous cell carcinoma (ESCC) is the most common type of esophageal cancer, and its development, growth, and invasiveness are regulated by the tumor microenvironment (TME). Insulin-like growth factor-binding protein-7 (IGFBP7), which is closely related to various tumors, transforming growth factor-β1 (TGFβ1), which is a key signal mediator in oncogenesis, α-smooth muscle actin (α-SMA), and collagen I are important components of the TME. IGFBP7 can upregulate the expression of TGFβ1 and activate the TGFβ1/SMAD signaling pathway, which leads to an increase in collagen I in hepatic stellate cells (HSCs). However, the contribution of IGFBP7 to TGFβ1 and the TME in the progression of ESCC remains unknown. In the present study, we investigated IGFBP7 expression and its effects on TGFβ1 and the TME in ESCC. A total of 45 patients were divided into three groups: early-tumor group (n=15), advanced-tumor group (n=15), and paracancer control group (n=15). The EC109 cell line was cultured and treated with AdIGFBP7 and LvshTGFβ1, and the expression levels of IGFBP7, TGFβ1, α-SMA, collagen I, and p-SMAD2/3 were determined by immunohistochemical staining and western blotting analysis. IGFBP7, TGFβ1, α-SMA, and collagen I were upregulated in the ESCC samples compared with the control samples (P<0.05), and the values peaked in the advanced-tumor group (P<0.05). Compared with the control group, the TGFβ1, α-SMA, p-SMAD2/3, and collagen I proteins were gradually increased from 24 to 72 h in the EC109 cells treated with AdIGFBP7 (P<0.05). Inhibition of TGFβ1 expression in the EC109 cells treated with AdIGFBP7 gradually reduced the expression of α-SMA, collagen I, and p-SMAD2/3 from 24 to 72 h (P<0.05). These findings suggest that increased IGFBP7 may accelerate the progression of ESCC by upregulating TGFβ1, α-SMA, and collagen I via activating the TGFβ1/SMAD signaling pathway, which could remodel the TME.