<p>Biological Roles and Mechanisms of Circular RNA in Human Cancers</p>

Abstract

Circular RNA (circRNA) is an intriguing class of RNA with covalently closedloop structure and is highly stable and conservative. As new members of the ncRNAs, the function, mechanism, potential diagnostic biomarker, and therapeutic target have raised increased attention. Most circRNAs are presented with characteristics of abundance, stability, conservatism, and often exhibiting tissue/developmental-stage-specific manner. Over 30,000 circRNAs have been identified with their unique structures to maintain stability more easily than linear RNAs. An increased numbers of circRNAs are dysregulated and involved in several biological processes of malignance, such as tumorigenesis, growth, invasion, metastasis, apoptosis, and vascularization. Emerging evidence suggests that circRNAs play important roles by acting as miRNA sponge or protein scaffolding, autophagy regulators, and interacting with RNA-binding protein (RBP), which may potentially serve as a novel promising biomarker for prevention, diagnosis and therapeutic target for treatment of human cancer with great significance either in scientific research or clinic arena. This review introduces concept, major features of circRNAs, and mainly describes the major biological functions and clinical relevance of circRNAs, as well as expressions and regulatory mechanisms in various types of human cancer, including pathogenesis, mode of action, potential target, signaling regulatory pathways, drug resistance, and therapeutic biomarkers. All of which provide evidence for the potential utilities of circRNAs in the diagnosis and treatment of cancer.

<p>The Novel Circular RNA Circ-PGAP3 Promotes the Proliferation and Invasion of Triple Negative Breast Cancer by Regulating the miR-330-3p/Myc Axis</p>

“…10 In recent years, an increasing number of studies have shown that circRNA is frequently abnormally expressed in various human cancer types, and it functions as a fundamental player in tumorigenesis and development through direct or indirect ways. [11][12][13] However, the molecular function and biological role of circRNA in TNBC remain largely unknown. In a previous study, Zeng et al performed circRNA high-throughput sequencing in paired TNBC and normal tissues, and found a large number of dysregulated circRNAs, including circ-PGAP3 (hsa_-circ_0106800, chr17: 37843549-37844086).…”

Non-Coding and Regulatory RNAs as Epigenetic Remodelers of Fatty Acid Homeostasis in Cancer

“…CircRNAs are single-stranded RNA with their 3′ and 5′ ends covalently linked [ 22 ]. They operate as effective microRNA sponges, gene splicing, transcription, and translation regulators and interact with RNA-binding proteins [ 23 , 24 ]. As a general view, Figure 1 encapsulates the reviewed ncRNAs targeting FA metabolism pathways in this manuscript.…”

Circ_0004913 sponges miR-1290 and regulates FOXC1 to inhibit the proliferation of hepatocellular carcinoma

“…Circular RNAs (circRNAs) are a new type of non-coding RNAs, characterized by continuous covalent closed loop without 5′-cap structure or 3′-poly A tail, and considered as a by-product of splicing error [6]. Aberrant expression of circRNAs have also been shown to be associated with the initiation and development of various diseases, including cancers [7]. For example, circRNA FARSA promoted colorectal cancer cell growth, while cir-cRNA UBAP2 increased SEMA6D expression to enhance cisplatin resistance in osteosarcoma [8,9].…”