M6A-Mediated Upregulation of CircMDK Promotes Tumorigenesis and Acts as a Nanotherapeutic Target in Hepatocellular Carcinoma

Abstract

Background: Emerging evidences suggest the critical role of circular RNAs (circRNAs) in disease development especially in various cancers. However, the oncogenic role of circRNAs in hepatocellular carcinoma (HCC) is still largely unknown.Methods: RNA sequencing was performed to identify significantly upregulated circRNAs in paired HCC and non-tumor tissues. CCK-8 assay, colony formation, transwell, and xenograft mouse models were used to investigate the role of circRNAs in HCC proliferation and metastasis. Small interfering RNA (siRNA) was used to silence gene expression. RNA immunoprecipitation, biotin pull-down, RNA pull-down, luciferase reporter assay and western blot were used to explore the underlying molecular mechanisms.Results: Hsa_circ_0095868, derived from exon 5 of the MDK gene (named circMDK), was identified as a new oncogenic circRNA that was significantly upregulated in HCC. The upregulation of circMDK was associated with the modification of N6-methyladenosine (m6A) and poor survival in HCC patients. Mechanistically, circMDK sponged miR-346 and miR-874-3p to upregulate ATG16L1, resulting to the activation of PI3K/Akt/mTOR signaling pathway to promote cell proliferation and migration. Poly (β-amino esters) (PAEs) were synthesized to assist the delivery of circMDK siRNA (PAE-siRNA), which effectively inhibited tumor progression in four liver tumor models including subcutaneous, metastatic, orthotopic and patient-derived xenograft (PDX) models without obvious adverse effects.Conclusions: CircMDK could serve as a potential tumor biomarker that promotes the progression of HCC via the miR-346/874-3p-ATG16L1 axis. The PAE-based delivery of siRNA improved the stability and efficiency of siRNA targeting circMDK. The PAE-siRNA nanoparticles effectively inhibited HCC proliferation and metastasis in vivo. Our current findings offer a promising nanotherapeutic strategy for the treatment of HCC.

A peptide translated from circPPP1R12A promotes the malignancy of non‐small cell lung cancer cells through AKT signaling pathway

“…To name only a few, Jie et al 27 have reported thathsa_ circ_0102004 promoted prostate cancer cell proliferation, Zheng et al 28 have reported that hsa_circ_0023028 contributed to the progression of laryngeal squamous cell carcinoma. Du et al 29 have also reported that hsa_circ_0095868 upregulated by M6A promotes the tumorigenesis of hepatocellular carcinoma. Our study focused on the role of circPPP1R12A in NSCLC.…”

The roles of N6-methyladenosine and its target regulatory noncoding RNAs in tumors: classification, mechanisms, and potential therapeutic implications

“…IGF2BP1 recognizes the m6A modification site in circMDK to increase the stability of its transcripts. circMDK sponges miR-346, and miR-874-3p upregulates autophagy-related 16-like 1 (ATG16L1), thereby activating the PI3K/AKT/mTOR signaling pathway and promoting HCC cell proliferation, migration and invasion 134 . METTL3 and IGF2BP1 act together to increase the stability of LncAROD through m6A modification.…”

“…Tumor growth was significantly suppressed by in vivo-optimized RNA interference (RNAi) inhibition of LINRIS 156 . PAEs to assist in the transport of circMDK siRNA (PAE-siRNA) were demonstrated to be effective in inhibiting tumor progression without causing significant adverse effects in four HCC models, including a subcutaneous model, orthotopic model, lung metastasis model and PDX model 134 . These studies suggest that targeting RNA effector molecules for clinical treatment is a promising research direction.…”

Circular RNAs: Biomarkers of cancer

“…CircMDK is novel oncogenic circRNA in hepatocellular carcinoma (HCC) with significantly increased expression in tumors. CircMDK promotes HCC progression via the miR‐346/miR‐874‐3p‐ATG16L1 axis and may be a therapeutic target for HCC [33]. M 6 A‐modified circMAP3K4 encodes a novel peptide, circMAP3K4‐455 aa, which prevents apoptosis in HCC [34].…”