Exosomal circRNAs: A key factor of tumor angiogenesis and therapeutic intervention.

Over the last few decades, our understanding of the molecular mechanisms underlying tumor angiogenesis has advanced at a significant pace and the clinical translation of these mechanisms has benefited millions of patients. However, limited efficacy and the rapid expansion of drug resistance remain unresolved issues. Recent studies in both preclinical and clinical settings have revealed that circRNAs, as a novel identified non-coding RNA can mediate intercellular communication and regulate the microenvironment within tumors after being selectively packaged, secreted, and transmitted via exosomes. This review aims to provide a comprehensive understanding of how exosomal circRNAs orchestrate inducers and inhibitors of angiogenesis, including their functions, molecular mechanisms, and potential roles as diagnostic biomarkers and therapeutic targets. Finally, we discuss the technological advances in exosome functionalization and exosome-mimetic nanovesicles intending to improve the clinical translation of exosomal circRNAs.

Screening and Validation of the Hypoxia-Related Signature of Evaluating Tumor Immune Microenvironment and Predicting Prognosis in Gastric Cancer.

Background: Hypoxia is one driving factor of gastric cancer. It causes a series of immunosuppressive processes and malignant cell responses, leading to a poor prognosis. It is clinically important to identify the molecular markers related to hypoxia. Methods: We screened the prognostic markers related to hypoxia in The Cancer Genome Atlas database, and a risk score model was developed based on these markers. The relationships between the risk score and tumor immune microenvironment were investigated. An independent validation cohort from Gene Expression Omnibus was applied to validate the results. A nomogram of risk score model and clinicopathological factor was developed to individually predict the prognosis. Results: We developed a hypoxia risk score model based on SERPINE1 and EFNA3. Quantified real-time PCR was further applied to verified gene expressions of SERPINE1 and EFNA3 in gastric cancer patients and cell lines. A high-risk score is associated with a poor prognosis through the immunosuppressive microenvironment and immune escape mechanisms, including infiltration of immunosuppressive cells, expression of immune checkpoint molecules, and enrichment of signal pathways related to cancer and immunosuppression. The nomogram basing on the hypoxia-related risk score model showed a good ability to predict prognosis and high clinical net benefits. Conclusions: The hypoxia risk score model revealed a close relationship between hypoxia and tumor immune microenvironment. The current study potentially provides new insights of how hypoxia affects the prognosis, and may provide a new therapeutic target for patients with gastric cancer.