CircNFIB inhibits tumor growth and metastasis through suppressing MEK1/ERK signaling in intrahepatic cholangiocarcinoma

Abstract

Background Considerable evidence shows that circular RNAs (circRNAs) play an important role in tumor development. However, their function in intrahepatic cholangiocarcinoma (ICC) metastasis and the underlying mechanisms are incompletely understood. Methods circNFIB (hsa_circ_0086376, termed as cNFIB hereafter) was identified in human ICC tissues through circRNAs sequencing. The biological role of cNFIB was determined in vitro and in vivo by gain or loss of functional experiments. Fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP) and RNA pull-down assays were conducted to analyze the interaction of cNFIB with dual specificity mitogen-activated protein kinase kinase1 (MEK1). Duolink in situ proximity ligation assay (PLA) and coimmunoprecipitation (co-IP) assay were used to investigate the effects of cNFIB on the interaction between MEK1 and mitogen-activated protein kinase 2 (ERK2). Finally, a series of in vitro and in vivo experiments were performed to explore the influences of cNFIB on the anti-tumor activity of trametinib (a MEK inhibitor). Results cNFIB was significantly down-regulated in human ICC tissues with postoperative metastases. The loss of cNFIB was highly associated with aggressive characteristics and predicted unfavorable prognosis in ICC patients. Functional studies revealed that cNFIB inhibited the proliferation and metastasis of ICC cells in vitro and in vivo. Mechanistically, cNFIB competitively interacted with MEK1, which induced the dissociation between MEK1 and ERK2, thereby resulting in the suppression of ERK signaling and tumor metastasis. Moreover, we found that ICC cells with high levels of cNFIB held the potential to delay the trametinib resistance. Consistently, in vivo and in vitro studies demonstrated that cotreatment with trametinib and lentivirus vector encoding cNFIB showed greater inhibitory effect than isolated trametinib treatment. Conclusions Our findings identified that cNFIB played a key role in ICC growth and metastasis by regulating MEK1/ERK signaling. Given the efficacy of cNFIB modulation on ICC suppression and trametinib sensitivity, cNFIB appears to be a potential therapeutic molecule for ICC treatment.

Antitumor Effects of Delta (9)-Tetrahydrocannabinol and Cannabinol on Cholangiocarcinoma Cells and Xenograft Mouse Models

“…Furthermore, the abnormal regulation of kinase and phosphatase signaling pathways plays a principal role in oncogenic pathway activation in numerous cancers [ 6 , 7 ]. Previous research demonstrated that ERK signaling modulation inhibits CCA proliferation and metastasis [ 8 ]. Moreover, the suppression of VEGFR2 phosphorylation levels reduces the PI3K/AKT signaling pathway, resulting in alterations in CCA cell proliferation, apoptosis, and invasion [ 9 ].…”

Elucidating the role of circNFIB in myocardial fibrosis alleviation by endogenous sulfur dioxide

“…Nfib encodes nuclear factor 1 B-type (NF1-B), which is relatively highly expressed in the mouse heart and is involved in DNA replication, transcription and transcription regulation [ 11 ]. Du et al found that circNFIB may be used as a biomarker for intrahepatic cholangiocarcinoma (ICC) patients, and the circNFIB-MEK-ERK axis may be a potential therapeutic target for ICC treatment [ 37 ]. In addition, a recent study reported that circNFIB plays a critical role in improving cardiac fibrosis in vivo and in vitro in an MI model [ 11 ].…”

Hsa_circ_0019054 up-regulates HIF1A through sequestering miR-340–5p to promote the tumorigenesis of intrahepatic cholangiocarcinoma

“…For instance, circNFIB was demonstrated to repress the metastasis and growth and promote trametinib sensitivity in ICC by blocking MEK1/ERK pathway. 19 Xu et al showed that high circHMGCS1-016 was associated with recurrence and unfavorable prognosis of ICC patients, and showed an immunosuppressive role to contribute to immune tolerance by reducing CD8 + T cells infiltration in ICC. 20 Thus, circRNAs have great potential as biomarkers for ICC molecular therapy.…”

“…For instance, circNFIB was demonstrated to repress the metastasis and growth and promote trametinib sensitivity in ICC by blocking MEK1/ERK pathway. 19 Xu et al…”