CircSETD3 (hsa_circ_0000567) inhibits proliferation and induces apoptosis in cholangiocarcinoma cells via downregulation of microRNA-421 expression

Abstract

Cholangiocarcinoma (CCA) is a fatal tumor associated with chronic inflammation. Circular RNAs (circRNAs) have been evidenced to be involved in tumorigenesis and tumor progression. This study aimed to explore the effects and potential molecular mechanism of circSETD3 in CCA progression. Levels of CircSETD3 and microRNA (miR)-421 in CCA tissue and cell lines were measured using quantitative real-time polymerase-chain reaction (qRT-PCR). A direct target of miR-421 was predicted using TargetScan and further confirmed by a dual-luciferase reporter assay. Cell proliferation and apoptosis were measured using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and flow cytometry, respectively. The activity of caspase-3 was also examined using caspase-3 activity detection kits. Moreover, the levels of B-cell lymphoma-2 modifying factor ( BMF ), B-cell lymphoma 2 ( BCL2 ), and Bcl-2-associated X protein ( BAX ) in TFK1 cells were assessed using qRT-PCR and western blot analysis. We found that circSETD3 was downregulated, while miR-421 was upregulated in CCA tissues and cell lines. CircSETD3 negatively regulated miR-421 levels in TFK1 cells. Functional assays revealed that circSETD3-plasmid inhibited cell proliferation, induced apoptosis, promoted caspase-3 activity, enhanced Bax and cleaved-Caspase 3 expression, and reduced Bcl-2 levels, and these effects were reversed by miR-421 mimic. Meanwhile, similar results were observed in miR-421 inhibitor-transfected TFK1 cells, and these results were abolished by BMF-siRNA. BMF, a direct target of miR-421, was downregulated in CCA tissues and cell lines. These findings demonstrate that circSETD3 inhibits proliferation and induces apoptosis in CCA cells by regulating the miR-421/BMF axis, indicating its potential as a promising candidate for CCA therapy.

Downregulated antisense lncRNA ENTPD3-AS1 contributes to the development of lung adenocarcinoma

“…The current study identified the reduced expression of ENTPD3-AS1 in LUAD patients, who have poor clinical outcomes, supporting that ENTPD3-AS1 could act as a promising prognostic predictor in LUAD. miR-421, which is an oncomir associated with various cancers, including pancreatic cancer, cholangiocarcinoma, and LUAD [22][23][24], is sponged by ENTPD3-AS1. Indeed, the knockdown of ENTPD3-AS1 or miR-421 inhibitors decreased cell proliferation, enhanced cell migration and epithelial phenotype transition in A549 cells, supporting the findings that ENTPD3-AS1 inhibited the oncogenic function of miR-421 in LUAD.…”

Programmed Cell Death Pathways in Cholangiocarcinoma: Opportunities for Targeted Therapy

“…Numerous studies highlight the implication of microRNAs (miRNAs) in cancer research, as they play an important role in regulating cancer cells and impacting various aspects of cancer progression, including apoptosis induction, cell cycle regulation, metastasis promotion, and angiogenesis stimulation [30,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78]. In a recent investigation by Xiong et al [79], the effects of circSETD3, a circular RNA containing multiple miRNA binding sites, were studied in CCA cells. The experimental research also focused on miR-421, which was described to promote cell proliferation in human gastric cancer.…”

“…circSETD3 has been implicated in CCA progression. [79] miR-421 It promotes cell proliferation in human gastric cancer and represents a promising therapeutic target for CCA treatment. [80,81] miR-373 Its overexpression promotes apoptosis in CCA cells by targeting ULK1.…”

Exosomal circ-PTPN22 and circ-ADAMTS6 mark T cell exhaustion and neutrophil extracellular traps in Asian intrahepatic cholangiocarcinoma

“…For example, cerebellar degenerative-related protein-1 antisense (CDR1as), which has been extensively studied in multiple cancer types, 10 can serve as a biomarker for ICC. 11 Similarly, circ_0005230, 12 circDNM3OS, 13 circ-LAMP1, 14 circ0021205, 15 circRTN4IP1, 16 and circSETD3 17 can promote the proliferation, growth, or metastases of ICC. circ_0020256, 18 which is associated with the tumor microenvironment, is an exosomal circRNA produced by tumor-associated M2 macrophages and promotes cancer progression.…”