Exosome-transferred hsa_circ_0014235 promotes DDP chemoresistance and deteriorates the development of non-small cell lung cancer by mediating the miR-520a-5p/CDK4 pathway

Abstract

Background Circular RNAs (circRNAs) play crucial roles in the development and progression of human cancers, including non-small cell lung cancer (NSCLC). However, most of these circRNAs, such as hsa_circ_0014235, are not fully identified in functions and mechanisms. Methods The isolated exosomes from serum specimens were identified using transmission electron microscopy (TEM). The expression of hsa_circ_0014235, miR-520a-5p and cyclin-dependent kinase 4 (CDK4) was detected by real-time quantitative polymerase chain reaction (qPCR). For functional assays, cell proliferation, colony formation ability, migration, invasion, cell apoptosis and cell cycle progression were determined using cell counting kit-8 (CCK-8) assay, colony formation assay, wound healing assay, transwell assay and flow cytometry assay, respectively. The expression of CDK4 and other indicated marker proteins was detected by western blot. The predicted target relationship between miR-520a-5p and hsa_circ_0014235 or cyclin-dependent kinase 4 (CDK4) was verified by dual-luciferase reporter assay or RNA immunoprecipitation (RIP) assay. Results The expression of hsa_circ_0014235 was notably elevated in NSCLC serum-derived exosomes, tumor tissues and cells. NSCLC serum-derived exosomes promoted NSCLC cell resistance to cisplatin (DDP), cell proliferation, migration and invasion in vitro, as well as tumor growth and DDP resistance in vivo. Hsa_circ_0014235 overexpression enhanced DDP resistance and facilitated cell malignant behaviors. MiR-520a-5p was a target of hsa_circ_0014235, and rescue experiments showed that miR-520a-5p restoration reversed the effects of hsa_circ_0014235 overexpression. Moreover, CDK4 was a target of miR-520a-5p, and rescue experiments showed that CDK4 knockdown reversed the aggressive effects of miR-520a-5p inhibition on NSCLC progression. Conclusions Exosome-transmitted hsa_circ_0014235 promoted NSCLC malignant development by mediating the miR-520a-5p/CDK4 regulatory axis.

N6-methyladenosine-modified circIGF2BP3 inhibits CD8+ T-cell responses to facilitate tumor immune evasion by promoting the deubiquitination of PD-L1 in non-small cell lung cancer

“…Accumulating evidence has confirmed the roles of circRNAs in regulating the proliferation, metastasis, stemness and resistance to therapy of NSCLC [ 13 – 15 ]. For instance, circPPKCI accelerates the proliferation and progression of NSCLC by sponging miR-545 and miR-589, thus promoting transcription factor E2F7 expression [ 16 ], while hsa_circ_0014235 increases the resistance of NSCLC cells to cisplatin by enhancing CDK4 expression [ 17 ]. However, the biological implications of circRNAs in regulating antitumor immunity in NSCLC remain unclear.…”

CircRNA Microarray Profiling Reveals hsa_circ_0058493 as a Novel Biomarker for Imatinib-Resistant CML

“…Multiple studies had depicted that circRNAs in exosomes served as novel important biomarkers since the circRNAs related to tumor progression or drug resistance could be horizontally transmitted, thus interfering with the biological functions of adjacent or distant recipient cells, and detected in body fluids of patients ( Tang et al, 2018 ; Fan et al, 2019 ; Xu X. et al, 2020 ; Wu et al, 2020 ; Xie et al, 2020 ). However, whether circRNAs encapsulated and transmitted by exosomes could change the biological functions of CML cells has not been explored.…”

“…Exosomes can be secreted by all cell types and have been found in nearly all body fluids including plasma and serum ( Doyle and Wang, 2019 ). Studies have shown that serum exosomal circRNAs are relevant to the clinical efficacy of patients with cancer, serving as promising biomarkers for liquid biopsy ( Xu X. et al, 2020 ; Xie et al, 2020 ). However, the cellular functions of circRNAs and exosomal circRNAs in CML have not been well explored.…”

Bioinformatics Analysis of Choriocarcinoma-Related MicroRNA-Transcription Factor-Target Gene Regulatory Networks and Validation of Key miRNAs

“… 60 In addition, MAP7 interacts with RC3H1 to upregulate the cell cycle progression of cervical cancer cells by activating NF-κB signalling. 61 Previous studies showed that low expression of miR-520a-5p promotes cancer cell migration and invasion in tissues, such as lung cancer 62 and breast cancer. 63 A prospective pilot study showed that miR-520a-5p could be used as an effective foetal/placenta-specific marker for the diagnosis and continuous follow-up of GTD/GTN, especially for patients with HCG false-positive and HCG-negative results.…”