NOX5 mediates the crosstalk between tumor cells and cancer-associated fibroblasts via regulating cytokine network

The emerging role of lactate in tumor microenvironment and its clinical relevance

In recent years, the significant impact of lactate in the tumor microenvironment has been greatly documented. Acting not only as an energy substance in tumor metabolism, lactate is also an imperative signaling molecule. It plays key roles in metabolic remodeling, protein lactylation, immunosuppression, drug resistance, epigenetics and tumor metastasis, which has a tight relation with cancer patients' poor prognosis. This review illustrates the roles lactate plays in different aspects of tumor progression and drug resistance. From the comprehensive effects that lactate has on tumor metabolism and tumor immunity, the therapeutic targets related to it are expected to bring new hope for cancer therapy.

circNOX4 activates an inflammatory fibroblast niche to promote tumor growth and metastasis in NSCLC via FAP/IL-6 axis

BACKGROUND

Cancer-associated fibroblasts (CAFs) orchestrate a supportive niche that fuels cancer metastatic development in non-small cell lung cancer (NSCLC). Due to the heterogeneity and plasticity of CAFs, manipulating the activated phenotype of fibroblasts is a promising strategy for cancer therapy. However, the underlying mechanisms of fibroblast activation and phenotype switching that drive metastasis remain elusive.

METHODS

The clinical implications of fibroblast activation protein (FAP)-positive CAFs (FAP+CAFs) were evaluated based on tumor specimens from NSCLC patients and bioinformatic analysis of online databases. CAF-specific circular RNAs (circRNAs) were screened by circRNA microarrays of primary human CAFs and matched normal fibroblasts (NFs). Survival analyses were performed to assess the prognostic value of circNOX4 in NSCLC clinical samples. The biological effects of circNOX4 were investigated by gain- and loss-of-function experiments in vitro and in vivo. Fluorescence in situ hybridization, luciferase reporter assays, RNA immunoprecipitation, and miRNA rescue experiments were conducted to elucidate the underlying mechanisms of fibroblast activation. Cytokine antibody array, transwell coculture system, and enzyme-linked immunosorbent assay (ELISA) were performed to investigate the downstream effectors that promote cancer metastasis.

RESULTS

FAP+CAFs were significantly enriched in metastatic cancer samples, and their higher abundance was correlated with the worse overall survival in NSCLC patients. A novel CAF-specific circRNA, circNOX4 (hsa_circ_0023988), evoked the phenotypic transition from NFs into CAFs and promoted the migration and invasion of NSCLC in vitro and in vivo. Clinically, circNOX4 correlated with the poor prognosis of advanced NSCLC patients. Mechanistically, circNOX4 upregulated FAP by sponging miR-329-5p, which led to fibroblast activation. Furthermore, the circNOX4/miR-329-5p/FAP axis activated an inflammatory fibroblast niche by preferentially inducing interleukin-6 (IL-6) and eventually promoting NSCLC progression. Disruption of the intercellular circNOX4/IL-6 axis significantly suppressed tumor growth and metastatic colonization in vivo.

CONCLUSIONS

Our study reveals a role of the circRNA-induced fibroblast niche in tumor metastasis and highlights that targeting the circNOX4/FAP/IL-6 axis is a promising strategy for the intervention of NSCLC metastasis.

Cancer-associated fibroblasts-induced remodeling of tumor immune microenvironment via Jagged1 in glioma

Tumor immunosuppression are prominent characteristics of brain glioma. Current standard modality including surgical resection and chemoradiotherapy do not significantly improve clinical outcomes. Cancer-associated fibroblasts (CAFs) that regard as important stromal cells in tumor microenvironment have been confirmed to play crucial roles in tumor development. However, the effects of CAFs on tumor immunosuppression in glioma are not well expounded. In this study, we report that CAFs contributes to the formation of glioma immunosuppressive microenvironment. Specifically, we found that glioma-derived Jagged1 enhanced the proliferation and PD-L1 expression of CAFs in vitro. Importantly, we discovered that Notch1, c-Myc and PD-L1 expression were significantly increased in high Jagged1-expressing gliomas, moreover, we further confirmed that Notch1 and PD-L1 expression located on the CAFs in glioma tissues. We also found that glioma-derived Jagged1 promotes the increase of tumor-infiltrating macrophages, M2 macrophages and Foxp3 Treg cells, as well as no significance of M1 macrophages and CD8+ T cells, indicating potential immunosuppression. This study opens up novel therapeutic strategies reversing CAF immunosuppression for gliomas.

AKT2S128/CCTαS315/319/323-positive cancer-associated fibroblasts (CAFs) mediate focal adhesion kinase (FAK) inhibitors resistance via secreting phosphatidylcholines (PCs)

Abnormal metabolism is regarded as an oncogenic hallmark related to tumor progression and therapeutic resistance. Present study employed multi-omics, including phosphoproteomics, untargeted metabolomics and lipidomics, to demonstrate that the pAKT2 Ser128 and pCCTα Ser315/319/323-positive cancer-associated fibroblasts (CAFs) substantially release phosphatidylcholines (PCs), contributing to the resistance of focal adhesion kinase (FAK) inhibitors in esophageal squamous cell carcinoma (ESCC) treatment. Additionally, we observed extremely low levels of FAK Tyr397 expression in CAFs, potentially offering no available target for FAK inhibitors playing their anti-growth role in CAFs. Consequently, FAK inhibitor increased the intracellular concentration of Ca2+ in CAFs, promoting the formation of AKT2/CCTα complex, leading to phosphorylation of CCTα Ser315/319/323 sites and eventually enhancing stromal PC production. This activation could stimulate the intratumoral Janus kinase 2 (JAK2)/Signal transducer and activator of transcription 3 (STAT3) pathway, triggering resistance to FAK inhibition. Analysis of clinical samples demonstrated that stromal pAKT2 Ser128 and pCCTα Ser315/319/323 are related to the tumor malignancy and reduced patient survival. Pseudo-targeted lipidomics and further validation cohort quantitatively showed that plasma PCs enable to distinguish the malignant extent of ESCC patients. In conclusion, inhibition of stroma-derived PCs and related pathway could be possible therapeutic strategies for tumor therapy.

Emerging role of cancer-associated fibroblasts in esophageal squamous cell carcinoma

Esophageal carcinoma is the sixth leading cause of cancer death globally and the majority of global cases are esophageal squamous cell carcinoma (ESCC). Difficulty in diagnosis exists as more than 70% of ESCC patients are diagnosed at the intermediate or advanced stage. Cancer-associated fibroblasts (CAFs) have been considered one of the crucial components in the process of tumor growth, promoting communications between cancer cells and the tumor microenvironment (TME). CAFs grow alongside malignancies dynamically and interact with ESCC cells to promote their progression, proliferation, invasion, tumor escape, chemo- and radio-resistance, etc. It is believed that CAFs qualify as a promising direction for treatment. Analyzing CAFs' subtypes and functions will elucidate the involvement of CAFs in ESCC and aid in therapeutics. This review summarizes current information on CAFs in ESCC and focuses on the latest interaction between CAFs and ESCC cancer cell discoveries. The origin of CAFs and their communication with ESCC cells and TME are also demonstrated. On the foundation of a thorough analysis, we highlight the clinical prospects and CAFs-related therapies in ESCC in the future.

Role of cancer-associated fibroblasts in the progression, therapeutic resistance and targeted therapy of oesophageal squamous cell carcinoma

Oesophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignant tumours with high morbidity and mortality. Although surgery, radiotherapy and chemotherapy are common treatment options available for oesophageal cancer, the 5-year survival rate remains low after treatment. On the one hand, many oesophageal cancers are are discovered at an advanced stage and, on the other hand, treatment resistance is a major obstacle to treating locally advanced ESCC. Cancer-associated fibroblasts (CAFs), the main type of stromal cell in the tumour microenvironment, enhance tumour progression and treatment resistance and have emerged as a major focus of study on targeted therapy of oesophageal cancer.With the aim of providing potential, prospective targets for improving therapeutic efficacy, this review summarises the origin and activation of CAFs and their specific role in regulating tumour progression and treatment resistance in ESCC. We also emphasize the clinical potential and emerging trends of ESCC CAFs-targeted treatments.

Lymphangiogenesis in gastric cancer: function and mechanism

Increased lymphangiogenesis and lymph node (LN) metastasis are thought to be important steps in cancer metastasis, and are associated with patient's poor prognosis. There is increasing evidence that the lymphatic system may play a crucial role in regulating tumor immune response and limiting tumor metastasis, since tumor lymphangiogenesis is more prominent in tumor metastasis and diffusion. Lymphangiogenesis takes place in embryonic development, wound healing, and a variety of pathological conditions, including tumors. Tumor cells and tumor microenvironment cells generate growth factors (such as lymphangiogenesis factor VEGF-C/D), which can promote lymphangiogenesis, thereby inducing the metastasis and diffusion of tumor cells. Nevertheless, the current research on lymphangiogenesis in gastric cancer is relatively scattered and lacks a comprehensive understanding. Therefore, in this review, we aim to provide a detailed perspective on molecules and signal transduction pathways that regulate gastric cancer lymphogenesis, which may provide new insights for the diagnosis and treatment of cancer.

The role of peroxisome proliferator-activated receptors in the tumor microenvironment, tumor cell metabolism, and anticancer therapy

Peroxisome proliferator-activated receptors (PPARs) have been extensively studied for over 3 decades and consist of three isotypes, including PPARα, γ, and β/δ, that were originally considered key metabolic regulators controlling energy homeostasis in the body. Cancer has become a leading cause of human mortality worldwide, and the role of peroxisome proliferator-activated receptors in cancer is increasingly being investigated, especially the deep molecular mechanisms and effective cancer therapies. Peroxisome proliferator-activated receptors are an important class of lipid sensors and are involved in the regulation of multiple metabolic pathways and cell fate. They can regulate cancer progression in different tissues by activating endogenous or synthetic compounds. This review emphasizes the significance and knowledge of peroxisome proliferator-activated receptors in the tumor microenvironment, tumor cell metabolism, and anti-cancer treatment by summarizing recent research on peroxisome proliferator-activated receptors. In general, peroxisome proliferator-activated receptors either promote or suppress cancer in different types of tumor microenvironments. The emergence of this difference depends on various factors, including peroxisome proliferator-activated receptor type, cancer type, and tumor stage. Simultaneously, the effect of anti-cancer therapy based on drug-targeted PPARs differs or even opposes among the three peroxisome proliferator-activated receptor homotypes and different cancer types. Therefore, the current status and challenges of the use of peroxisome proliferator-activated receptors agonists and antagonists in cancer treatment are further explored in this review.

Podoplanin promotes the carcinogenicity of gastric cancer by activating ezrin and mediating the crosstalk between tumour cells and cancer-associated fibroblasts

NEW FINDINGS

What is the central question of this study? To reveal the role and biological mechanism of PDPN in the progression of gastric cancer. What is the main finding and its importance? This study focused on a prognostic predictor, PDPN, which acted as a promoter in the progression of gastric cancer through the activation of Ezrin expression and CAFs. This finding may expand a new route for the gene-targeted therapy in gastric cancer.

ABSTRACT

Gastric cancer (GC) is a frequent malignant disease and the main cause of cancer-related death in the world. Podoplanin (PDPN) has been proved to be involved in the progression of various cancers. However, the role and biological mechanism of PDPN in GC are still vague. In our study, we detected the expression of PDPN in GC tissues and cell lines using RT-qPCR, western blot and datasets. The overall survival of GC patients was analysed with a Kaplan-Meier plot. The effects of PDPN overexpression and silencing on GC cell progression were assessed by Cell Counting Kit-8, flow cytometry and a wound healing assay. Besides, the modulation of PDPN on ezrin activation was investigated. We further explored the role of PDPN in the crosstalk between GC cells and cancer associated fibroblasts (CAFs). Results showed that PDPN was upregulated in GC tissues and cell lines. High expression of PDPN was correlated with poor prognosis of GC patients. PDPN positively regulated the viability, migration and invasion, but inhibited apoptosis, of GC cells by mediating the activation of ezrin. Meanwhile, the change in PDPN in GC cells activated CAFs and promoted the production of cytokines secreted by CAFs, which induced the progression of GC cells. These findings may provide a novel target for GC therapy.

Cancer-associated fibroblasts: Versatile mediators in remodeling the tumor microenvironment

Current cancer therapeutic strategies are generally not sufficient to eradicate malignancy, as cancer stroma cells contribute to tumor evasion and therapeutic resistance. Cancer-associated fibroblasts (CAFs) constitute a largely heterogeneous type of stromal cell population and are important components of the tumor microenvironment (TME). CAFs are the most abundant stromal cell type and are actively involved in tumor progression through complex mechanisms involving effects on other cell types. Research conducted in recent years has emphasized an emerging function of CAFs in the remodeling of the TME that promotes tumor progression with effects on response to treatment by various molecular mechanisms. A comprehensive mechanism of tumor-promoting activities of CAFs could facilitate the development of novel diagnostic and therapeutic approaches. In this review, the biological characterization of CAFs and the mechanisms of their effects on TME remodeling are summarized. Furthermore, we also highlight currently available therapeutic strategies targeting CAF in the context of optimizing the success of immunotherapies and briefly discuss possible future perspectives and challenges related to CAF studies.

PAFR/Stat3 axis maintains the symbiotic ecosystem between tumor and stroma to facilitate tumor malignancy

Stroma surrounding the tumor cells plays crucial roles for tumor progression. However, little is known about the factors that maintain the symbiosis between stroma and tumor cells. In this study, we found that the transcriptional regulator-signal transducer and activator of transcription 3 (Stat3) was frequently activated in cancer-associated fibroblasts (CAFs), which was a potent facilitator of tumor malignancy, and formed forward feedback loop with platelet-activating factor receptor (PAFR) both in CAFs and tumor cells. Importantly, PAFR/Stat3 axis connected intercellular signaling crosstalk between CAFs and cancer cells and drove mutual transcriptional programming of these two types of cells. Two central Stat3-related cytokine signaling molecules-interleukin 6 (IL-6) and IL-11 played the critical role in the process of PAFR/Stat3 axis-mediated communication between tumor and CAFs. Pharmacological inhibition of PAFR and Stat3 activities effectively reduced tumor progression using CAFs/tumor co-culture xenograft model. Our study reveals that PAFR/Stat3 axis enhances the interaction between tumor and its associated stroma and suggests that targeting this axis can be an effective therapeutic strategy against tumor malignancy.

Roles of IL-7R Induced by Interactions between Cancer Cells and Macrophages in the Progression of Esophageal Squamous Cell Carcinoma

High infiltration of tumor-associated macrophages (TAMs), which contribute to the progression of several cancer types, is correlated with poor prognosis of esophageal squamous cell carcinoma (ESCC). In addition to the previously reported increase in migration and invasion, ESCC cells co-cultured directly with macrophages exhibited enhanced survival and growth. Furthermore, interleukin-related molecules are associated with ESCC; however, the precise mechanism underlying this association is unclear. Therefore, we explored the role of interleukin-related molecules in ESCC progression. A cDNA microarray analysis of monocultured and co-cultured ESCC cells revealed that the interleukin 7 receptor (IL-7R) was upregulated in ESCC cells co-cultured with macrophages. Overexpression of IL-7R promoted the survival and growth of ESCC cells by activating the Akt and Erk1/2 signaling pathways. The IL-7/IL-7R axis also contributed to the promotion of ESCC cell migration via the Akt and Erk1/2 signaling pathways. Furthermore, immunohistochemistry showed that ESCC patients with high IL-7R expression in cancer nests exhibited a trend toward poor prognosis in terms of disease-free survival, and showed significant correlation with increased numbers of infiltrating macrophages and cancer-associated fibroblasts. Therefore, IL-7R, which is upregulated when directly co-cultured with macrophages, may contribute to ESCC progression by promoting the development of various malignant phenotypes in cancer cells.

Advancements in redox-sensitive micelles as nanotheranostics: A new horizon in cancer management

World Health Organisation (WHO) delineated cancer as one of the foremost reasons for mortality with 10 million deaths in the year 2020. Early diagnosis and effective drug delivery are of utmost importance in cancer management. The entrapment of both bio-imaging dyes and drugs will open novel avenues in the area of tumor theranostics. Elevated levels of reactive oxygen species (ROS) and glutathione (GSH) are the characteristic features of the tumor microenvironment (TME). Researchers have taken advantage of these specific TME features in recent years to develop micelle-based theranostic nanosystems. This review focuses on the advantages of redox-sensitive micelles (RSMs) and supramolecular self-assemblies for tumor theranostics. Key chemical linkers employed for the tumor-specific release of the cargo have been discussed. In vitro characterisation techniques used for the characterization of RSMs have been deliberated. Potential bottlenecks that may present themselves in the bench-to-bedside translation of this technology and the regulatory considerations have been deliberated.

Upregulation of circ_0035266 contributes to the malignant progression of inflammation-associated malignant transformed cells induced by tobacco-specific carcinogen NNK

Cigarette smoking-induced chronic inflammation has been considered a vital driver of lung tumorigenesis. The compounds 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific carcinogen, and lipopolysaccharide (LPS), an inflammatory inducer, are important components of tobacco smoke which have been implicated in inflammation-driven carcinogenesis. However, the biological effects and underlying mechanisms of LPS-mediated inflammation on NNK-induced tumorigenesis are still unclear. In this study, BEAS-2B human bronchial epithelial cells were exposed to NNK, LPS or both, for short- or long-term periods. We found that acute LPS exposure promoted the secretion of granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-6 in NNK-treated BEAS-2B cells. In addition, chronic LPS exposure facilitated the NNK-induced malignant transformation process by promoting cell proliferation, cell cycle alteration, migration and clonal formation. Previously, we determined that circular RNA circ_0035266 enhanced cellular inflammation in response to NNK+LPS by sponging miR-181d-5p and regulating expression of its downstream target DEAD-Box Helicase 3 X-Linked (DDX3X). Here, we found that knockdown of circ_0035266 or DDX3X led to a remarkable inhibition of the proliferation, cell cycle progression and migration of NNK+LPS-transformed BEAS-2B cells, while overexpression of these genes produced the opposite effects, indicating the oncogenic roles of circ_0035266 and DDX3X in the malignant progression of chronic inflammation-driven malignant transformed cells. Moreover, the regulatory relationships among circ_0035266, miR-181d-5p and DDX3X were further confirmed using a group of lung cancer tissues. Conclusively, our findings provide novel insights into our understanding of inflammation-driven tumorigenesis using a cellular malignant transformation model, and indicate a novel tumor-promoting role for circ_0035266 in chemical carcinogenesis.