circRNA TCFL5 Promote Esophageal Cancer Progression by Modulating M2 Macrophage Polarization via the miR-543-FMNL2 Axis

CircATXN7 regulates the proliferation and invasion of esophageal cancer cells through miR-4319/NLRC5

BACKGROUND

This study aimed to explore the molecular mechanism through which circular RNA of ataxin 7 (circATXN7) regulates the proliferation and invasion of esophageal cancer (EC) cells via microRNA (miR)-4319/NLR family CARD domain containing 5 (NLRC5).

METHODS

The localization of circATXN7 in EC cells was determined by RNA fluorescent in situ hybridization (RNA-FISH). The mRNA levels of circATXN7, miR-4319, and NLRC5 were quantified by reverse transcription-polymerase chain reactions. The binding activity of circATXN7 to miR-4319 was assessed using RNA-binding protein immunoprecipitation. Whether circATXN7 regulates the proliferation of EC cells via miR-4319 was explored using dual-luciferase reporter gene colony formation assays. Protein levels were quantified by western blot. The effect of NLRC5 on the proliferation and invasion of EC cells was examined using colony formation and Transwell assays. A subcutaneous transplanted tumor nude mouse model was established to observe the effect of circATXN7 on the proliferation of EC cells in vivo.

RESULTS

circATXN7 localized mainly to the cytoplasm. Overexpression or inhibition of miR-4319 significantly regulated the proliferation of EC cells, while circATXN7 competitively inhibited miR-4319 expression. Overexpression of miR-4319 significantly inhibited NLRC5 expression, indicating NLRC5 is a downstream regulatory target of miR-4319. circATXN7 influenced NLRC5 expression via miR-4319. In vivo tumor formation experiments in nude mice revealed that knocking down circATXN7 regulated NLRC5 expression via miR-4319 and significantly inhibited the proliferation of EC cells.

CONCLUSIONS

In vitro cell and in vivo animal experiments showed that circATXN7 regulates the proliferation, invasion, and migration of EC cells through the miR-4319/NLRC5 signaling pathway.

CircRNA Regulation of T Cells in Cancer: Unraveling Potential Targets

T lymphocytes play a critical role in antitumor immunity, but their exhaustion poses a significant challenge for immune evasion by malignant cells. Circular RNAs (circRNAs), characterized by their covalently closed looped structure, have emerged as pivotal regulators within the neoplastic landscape. Recent studies have highlighted their multifaceted roles in cellular processes, including gene expression modulation and protein function regulation, which are often disrupted in cancer. In this review, we systematically explore the intricate interplay between circRNAs and T cell modulation within the tumor microenvironment. By dissecting the regulatory mechanisms through which circRNAs impact T cell exhaustion, we aim to uncover pathways crucial for immune evasion and T cell dysfunction. These insights can inform innovative immunotherapeutic strategies targeting circRNA-mediated molecular pathways. Additionally, we discuss the translational potential of circRNAs as biomarkers for therapeutic response prediction and as intervention targets. Our comprehensive analysis aims to enhance the understanding of immune evasion dynamics in the tumor microenvironment by facilitating the development of precision immunotherapy.

Communication molecules (ncRNAs) mediate tumor-associated macrophage polarization and tumor progression

Non-coding RNAs play important roles in tumor cells and macrophages and participate in their communication as messengers. Non-coding RNAs have an impact in tumor cell proliferation, migration, and apoptosis, and they also regulate the differentiation and regulation of immune cells. In macrophages, they stimulate the polarization of macrophages into M1 or M2 by regulating proteins related to signaling pathways; in tumor cells, non-coding RNAs can enter macrophages through exosomes and affect the latter polarization. The polarization of macrophages further regulates the biological functions of cancer cells. The direction of macrophage polarization determines tumor progression, angiogenesis and drug resistance. This often creates a feedback loop. Non-coding RNAs act as bridges between tumor cells and macrophages to regulate the balance of the tumor microenvironment. We reviewed the signaling pathways related to macrophage polarization and the regulatory mechanisms of non-coding RNA in tumor-associated macrophages M1 and M2, and discussed the potential applications and prospects of exosome engineering.

A novel upregulated hsa_circ_0032746 regulates the oncogenesis of esophageal squamous cell carcinoma by regulating miR-4270/MCM3 axis

INTRODUCTION

Circular RNAs (CircRNA) have emerged as an interest of research in recent years due to its regulatory role in various kinds of cancers of human body. Esophageal squamous cell carcinoma (ESCC) is one of the major disease subtype in Asian countries, including China. CircRNAs are formed by back-splicing covalently joined 3'- and 5'- ends rather than canonical splicing and are found to have binding affinity with miRNAs that conjointly contribute to oncogenesis.

MATERIALS AND METHODS

4 pairs of normal, cancer adjacent tissues and cancer tissues were analyzed by high-throughput RNA sequencing and 84 differentially upregulated circRNAs were detected in cancer tissues. hsa_circ_0032746 was silenced by siRNA and lentivirus and then further proliferation, migration and invasion were performed by CCK-8 and transwell assays. Bioinformatic analysis  predicted binding affinity of circRNA/miRNA/mRNA axis.

RESULTS

After qPCR validation, we selected a novel upregulated hsa_circ_0032746 to explore its biogenetic functions which showed high expression in cancer tissues but not in cancer adjacent tissues. The clinicopathological relation of hsa_circ_0032746 showed positive correlation with the tumor location (P = 0.026) and gender (P = 0.05). We also predicted that hsa_circ_0032746 could sponge with microRNA. Bioinformatic analysis predicted 11 microRNA response element (MRE) sequences of hsa_circ_0032746 and dual luciferase reporter assay confirmed binding affinity with miR4270 evidencing further study of circRNA/miRNA role. The knockdown of hsa_circ_0032746 by siRNA and lentivirus demonstrated that proliferation, invasion and migration of ESCC were inhibited in vitro and vivo experiments. Bioinformatic analysis further predicted MCM3 as a target of miR-4270 and was found upregulated in ESCC upon validation. miR4270 mimic decreased the level of hsa_circ_0032746 and MCM3 while further rescue experiments demonstrated that hsa_circ_0032746 was dependent on miR4270/MCM3 axis on the development process of ESCC.

CONCLUSION

We revealed for the first time that circ_0032746/mir4270/MCM3 contributes in proliferation, migration and invasion of ESCC and could have potential prognostic and therapeutic significance.

Roles of circRNA dysregulation in esophageal squamous cell carcinoma tumor microenvironment

Esophageal squamous cell carcinoma (ESCC) is the most prevalent histological esophageal cancer characterized by advanced diagnosis, metastasis, resistance to treatment, and frequent recurrence. In recent years, numerous human disorders such as ESCC, have been linked to abnormal expression of circular RNAs (circRNAs), suggesting that they are fundamental to the intricate system of gene regulation that governs ESCC formation. The tumor microenvironment (TME), referring to the area surrounding the tumor cells, is composed of multiple components, including stromal cells, immune cells, the vascular system, extracellular matrix (ECM), and numerous signaling molecules. In this review, we briefly described the biological purposes and mechanisms of aberrant circRNA expression in the TME of ESCC, including the immune microenvironment, angiogenesis, epithelial-to-mesenchymal transition, hypoxia, metabolism, and radiotherapy resistance. As in-depth research into the processes of circRNAs in the TME of ESCC continues, circRNAs are promising therapeutic targets or delivery systems for cancer therapy and diagnostic and prognostic indicators for ESCC.

Regulation of the tumor immune microenvironment by cancer-derived circular RNAs

Circular RNA (circRNAs) is a covalently closed circular non-coding RNA formed by reverse back-splicing from precursor messenger RNA. It is found widely in eukaryotic cells and can be released to the surrounding environment and captured by other cell types. This, circRNAs serve as connections between different cell types for the mediation of multiple signaling pathways. CircRNAs reshape the tumor microenvironment (TME), a key factor involved in all stages of cancer development, by regulating epithelial-stromal transformation, tumor vascularization, immune cell function, and inflammatory responses. Immune cells are the most abundant cellular TME components, and they have profound toxicity to cancer cells. This review summarizes circRNA regulation of immune cells, including T cells, natural killer cells, and macrophages; highlights the impact of circRNAs on tumor progression, treatment, and prognosis; and indicates new targets for tumor immunotherapy.