Circular RNA CCDC66 Improves Murine Double Minute 4 (MDM4) Expression through Targeting miR-370 in Colorectal Cancer

Roles of circRNAs in the progression of colorectal cancer: novel strategies for detection and therapy

Endogenous noncoding RNAs with a covalently closed loop are known as circular RNAs (circRNAs). Recently, published works have revealed that circRNAs, which act as microRNA sponges, are critical for the biological behavior of several kinds of malignancies, including tumor cell proliferation, apoptosis, invasion, and metastasis. Additionally, there is a significant correlation between circRNAs and tumor resistance, stage, prognosis, and size. At present, colorectal cancer (CRC) is one of the most serious malignant tumors for human health. CircRNAs could represent potential targets to use in the prevention, diagnosis, and therapy of CRC, according to many studies. To fully comprehend the role of circRNAs in the incidence and progression of CRC, this review outlines the regulatory role and mechanisms of circRNAs in CRC and assesses their potential relevance as diagnostic and treatment possibilities for CRC. Our goal is to offer meaningful biological information for clinical evaluation and decision-making process for CRC treatment.

M2 macrophage-derived extracellular vesicles augment immune evasion and development of colorectal cancer via a circRNA_CCDC66/microRNA-342-3p/metadherin axis

The M2 macrophages are major components in the tumor microenvironment and are closely linked to immune suppression and tumor metastasis. This work focuses on how M2 macrophage-derived extracellular vesicles (EVs) affect colorectal cancer (CRC) progression. THP-1 monocytes were induced to differentiate to M0 or M2 macrophages, and the macrophage-derived EVs (M0-EVs and M2-EVs, respectively) were collected and identified. The M2-EVs stimulation augmented proliferation, mobility, and the in vivo tumorigenic activity of CRC cells. Circular RNA_CCDC66 (circ_CCDC66) was highly enriched in M2-EVs and could be delivered into CRC cells. The RNA pull-down and luciferase assays showed that circ_CCDC66 could competitively bind to microRNA (miR)-342-3p, therefore restoring the expression of metadherin (MTDH) mRNA, a target transcript of miR-342-3p. Suppression of circ_CCDC66 in the M2-EVs or specific knockdown of MTDH in CRC significantly blocked the growth and mobility of CRC cells. However, miR-342-3p inhibition restored the malignant phenotype of cancer cells. Moreover, the MTDH knockdown was found to increase the cytotoxicity of CD8+ T and reduce the protein level of the immune checkpoint PDL1 in CRC cells. In summary, this study reveals that the M2-EVs augment immune evasion and development of CRC by delivering circ_CCDC66 and restoring the MTDH level.

CircRNAs in colorectal cancer: potential biomarkers and therapeutic targets

Globally, colorectal cancer (CRC) is the third most prevalent cancer and the second leading cause of cancer-related deaths. Circular RNAs (circRNAs) are single-stranded RNA with covalently closed-loop structures and are highly stable, conserved, and abundantly expressed in various organs and tissues. Recent research found abnormal circRNA expression in CRC patients' blood/serum, cells, CRC tissues, and exosomes. Furthermore, mounting data demonstrated that circRNAs are crucial to the development of CRC. CircRNAs have been shown to exert biological functions by acting as microRNA sponges, RNA-binding protein sponges, regulators of gene splicing and transcription, and protein/peptide translators. These characteristics make circRNAs potential markers for CRC diagnosis and prognosis, potential therapeutic targets, and circRNA-based therapies. However, further studies are still necessary to improve the understanding of the roles and biological mechanisms of circRNAs in the development of CRC. In this review, up-to-date research on the role of circRNAs in CRC was examined, focusing on their potential application in CRC diagnosis and targeted therapy, which would advance the knowledge of the functions of circRNAs in the development and progression of CRC.

Recent findings on miR‑370 expression, regulation and functions in cancer (Review)

MicroRNAs (miRNAs/miRs) are a group of small non‑coding RNAs that serve as post‑transcriptional gene modulators. miRNAs have been demonstrated to serve a pivotal role in carcinogenesis and the dysregulated expression of miRNAs is a well‑understood characteristic of cancer. In recent years, miR‑370 has been established as a key miRNA in various cancers. The expression of miR‑370 is dysregulated in various types of cancer and varies markedly across different tumor types. miR‑370 can regulate multiple biological processes, including cell proliferation, apoptosis, migration, invasion, as well as cell cycle progression and cell stemness. Moreover, it has been reported that miR‑370 affects the response of tumor cells to anticancer treatments. Additionally, the expression of miR‑370 is modulated by multiple factors. The present review summarizes the role and mechanism of miR‑370 in tumors, and demonstrates its potential as a molecular marker for cancer diagnosis and prognosis.

Circular RNAs: New layer of complexity evading breast cancer heterogeneity

Advances in high-throughput sequencing techniques and bioinformatic analysis have refuted the "junk" RNA hypothesis that was claimed against non-coding RNAs (ncRNAs). Circular RNAs (circRNAs); a class of single-stranded covalently closed loop RNA molecules have recently emerged as stable epigenetic regulators. Although the exact regulatory role of circRNAs is still to be clarified, it has been proven that circRNAs could exert their functions by interacting with other ncRNAs or proteins in their own physiologically authentic environment, regulating multiple cellular signaling pathways and other classes of ncRNAs. CircRNAs have also been reported to exhibit a tissue-specific expression and have been associated with the malignant transformation process of several hematological and solid malignancies. Along this line of reasoning, this review aims to highlight the importance of circRNAs in Breast Cancer (BC), which is ranked as the most prevalent malignancy among females. Notwithstanding the substantial efforts to develop a suitable anticancer therapeutic regimen against the heterogenous BC, inter- and intra-tumoral heterogeneity have resulted in an arduous challenge for drug development research, which in turn necessitates the investigation of other markers to be therapeutically targeted. Herein, the potential of circRNAs as possible diagnostic and prognostic biomarkers have been highlighted together with their possible application as novel therapeutic targets.

CircCCDC66: Emerging roles and potential clinical values in malignant tumors

Circular RNAs (circRNAs) are endogenous non-coding RNAs (ncRNAs) with a closed-loop structure. In recent years, circRNAs have become the focus of much research into RNA. CircCCDC66 has been identified as a novel oncogenic circRNA and is up-regulated in a variety of malignant tumors including thyroid cancer, non-small cell carcinoma, gastric cancer, colorectal cancer, renal cancer, cervical cancer, glioma, and osteosarcoma. It mediates cancer progression by regulating epigenetic modifications, variable splicing, transcription, and protein translation. The oncogenicity of circCCDC66 suppresses or promotes the expression of related genes mainly through direct or indirect pathways. This finding suggests that circCCDC66 is a biomarker for cancer diagnosis, prognosis assessment and treatment. However, there is no review on the relationship between circCCDC66 and cancers. Thus, the expression, biological functions, and regulatory mechanisms of circCCDC66 in malignant tumor and non-tumor diseases are summarized. The clinical value and prognostic significance of circCCDC66 are also evaluated, which can provide insights helpful to those exploring new strategies for the early diagnosis and targeted treatment of malignancies.