Circular RNA circ-SMAD7 is downregulated in colorectal cancer and suppresses tumor metastasis by regulating epithelial mesenchymal transition

CircSOD2 Contributes to Tumor Progression, Immune Evasion and Anti-PD-1 Resistance in Hepatocellular Carcinoma by Targeting miR-497-5p/ANXA11 Axis

Circular RNAs (circRNAs) can function as functional molecules in hepatocellular carcinoma (HCC). Herein, circRNA superoxide dismutase 2 (circSOD2) was researched in HCC progression and immune system. The real-time polymerase chain reaction (qRT-PCR) was used for quantification of circSOD2, microRNA-497-5p (miR-497-5p) and Annexin A11 (ANXA11). Cell assays were performed by 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) and colony formation assays for proliferation, flow cytometry for apoptosis and cell cycle, wound healing assay for migration and transwell assay for migration/invasion. ANXA11 and metastatic protein levels were measured by western blot. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to analyze target binding. CD8⁺ T cell immunity was assessed by Immunohistochemistry (IHC) assay, and the effect of circSOD2 on programmed cell death 1 (PD-1) immune checkpoint inhibitors (anti-PD-1) therapy was evaluated by mice xenograft assay. CircSOD2 was upregulated in HCC tissues and cells. Knockdown of circSOD2 resulted in HCC cell growth inhibition, apoptosis promotion, cell cycle arrest and metastasis suppression. Mechanically, circSOD2 promoted HCC development by acting as a miR-497-5p sponge and miR-497-5p played a tumor-inhibitory role in HCC cells by targeting ANXA11. Moreover, circSOD2 induced upregulation of ANXA11 expression by interacting with miR-497-5p. Also, the promoting effects of circSOD2 on immune evasion and anti-PD-1 resistance were related to miR-497-5p/ANXA11 axis. This study elucidated the pivotal function of circSOD2 in HCC progression and immunosuppression by mediating miR-497-6p/ANXA11 axis. CircSOD2/miR-497-5p/ANXA11 axis was a novel view of circRNA research in HCC.

Non-coding RNAs as emerging regulators and biomarkers in colorectal cancer

CRC is the third most common cancer occurring worldwide and the second leading cause of cancer deaths. In the year 2020, 1,931,590 new cases of CRC and 935,173 deaths were reported. The last two decades have witnessed an intensive study of noncoding RNAs and their implications in various pathological conditions including cancer. Noncoding RNAs such as miRNAs, tsRNAs, piRNAs, lncRNAs, pseudogenes, and circRNAs have emerged as promising prognostic and diagnostic biomarkers in preclinical studies of cancer. Some of these noncoding RNAs have also been shown as promising therapeutic targets for cancer treatment. In this review, we have discussed the emerging roles of various types of noncoding RNAs in CRC and their future implications in colorectal cancer management and research.