m ⁶ A-modification regulated circ-CCT3 acts as the sponge of miR-378a-3p to promote hepatocellular carcinoma progression

Abstract

Background: Circular RNA (circRNA) plays a critical role in tumour progression. Circ-CCT3, a particularly abundant circRNA, was proposed to be involved in tumorigenesis. However, the role of circ-CCT3 in hepatocellular carcinoma remains elusive. Methods: Here, circ-CCT3 (a circRNA derived from exons 3, 4 and 5 of the CCT3 gene, hsa_circ_0004680) was identified by circRNA microarray and validated by qRT-PCR. RNA immunoprecipitation (RIP) was performed to confirm the binding between ALKBH5 along with METTL3 and circ-CCT3. Methylated RNA Immunoprecipitation (MeRIP) was used to detect the N6-methyladenosine (m 2 A) levels of circ-CCT3. CircRNAs in vivo precipitation, luciferase reporter assay, biotin-coupled microRNA capture, and fluorescence in situ hybridization were conducted to assess the interaction between circ-CCT3 and miR-378a-3p. The functions of circ-CCT3 in HCC were evaluated both in vitro and in vivo. Results: We demonstrated that circ-CCT3 was highly expressed in HCC which indicated the poor prognosis. Circ-CCT3 expression served as an independent risk factor for overall survival in patients with HCC. Knocking-down of circ-CCT3 inhibited the proliferation, invasion and migration of HCC cells, and angiogenesis of HUVEC. Mechanistically, ALKBH5 and METTL3 could bind and regulate m A-modification of circ-CCT3. Further, circ-CCT3 upregulated the expression of FLT-1 by sponging miR-378a-3p. Conclusions: Circ-CCT3 was significantly up-regulated in HCC and promoted liver cancer development via miR-378a-3p-FLT1 axis. It was also found that circ-CCT3 was under m A-modification mediated by ALKBH5 and METTL3. Our study highlights circ-CCT3 as a potential therapeutic target of HCC treatment, which provides a novel understanding on mechanisms of circRNAs in HCC progression.

Changes in m6A in Steatotic Liver Disease

“…m6A levels in Circ-CCT3, a circular RNA upregulated in human HCC tissue that promoted growth and migration of HCC cells by sponging miR-378a-3p, were decreased by METTL3 knockdown and increased by ALKBH5 knockdown. Additionally, knockdown of METTL3 increased Circ-CCT3 expression in HCC cells [128].…”

Non-coding RNA methylation modifications in hepatocellular carcinoma: interactions and potential implications

“…Except for KIAA1429, Liu et al revealed the involvement of ALKBH5 and METTL3 in binding to circ-CCT3, mediating its m6A modification. Upregulated in HCC, circ-CCT3 was proposed to function as a miR-378-3p sponge, thereby elevating FLT-1 expression and intensifying HCC proliferation, invasion, and migration [ 99 ]. Another study highlighted ALKBH5’s role in circCPSF6 demethylation, with YTHDF2 recognizing and destabilizing it [ 100 ].…”