LncRNA TTN-AS1 promotes the progression of cholangiocarcinoma via the miR-320a/neuropilin-1 axis

Abstract

Neuropilin-1 regulated by miR-320a participates in the progression of cholangiocarcinoma by serving as a co-receptor that activates multiple signaling pathways. The present study sought to investigate upstream lncRNAs that control the expression of miR-320a/neuropilin-1 axis and dissect some of the underlying mechanisms. Here we report lncRNA TTN-AS1 (titin-antisense RNA1) acts as a sponging ceRNA to downregulate miR-320a and is highly expressed in human cholangiocarcinoma tissues and cells. The expression of the above three molecules is correlated with the clinicopathologic parameters of cholangiocarcinoma patients. In this study, multiple bioinformatics tools and databases were employed to seek potential lncRNAs that have binding sites with miR-320a and TTN-AS1 was identified because it exhibited the largest folds of alteration between cholangiocarcinoma and normal bile duct epithelial cells. The regulatory role of TTN-AS1 on miR-320a was further evaluated by luciferase reporter and RNA pulldown assays, coupled with in situ hybridization and RNA immunoprecipitation analyses, which showed that TTN-AS1 bound to miR-320a through an argonaute2-dependent RNA interference pathway in the cytoplasm of cholangiocarcinoma cells. Knockdown and overexpression assays showed that the regulatory effect between TTN-AS1 and miR-320 was in a one-way manner. TTN-AS1 promoted the proliferation and migration of cholangiocarcinoma cells via the miR-320a/ neuropilin-1 axis. The function of TTN-AS1 on tumor growth and its interaction with miR-320a were confirmed in animal models. Further mechanistic studies revealed that TTA-AS1, through downregulating miR-320a, promoted cell cycle progression, epithelial-mesenchymal transition, and tumor angiogenesis by upregulating neuropilin-1, which co-interacted with the hepatocyte growth factor/c-Met and transforming growth factor (TGF)-β/ TGF-β receptor I pathways. In conclusion, the present results demonstrate that lncRNA TTA-AS1 is a sponging ceRNA for miR-320a, which in turn downregulates neuropilin-1 in cholangiocarcinoma cells, indicating these three molecules represent potential biomarkers and therapeutic targets in the management of cholangiocarcinoma.

Neuropilin-1: A feasible link between liver pathologies and COVID-19

“…Moreover, the association of NRP-1 and CCA development has been confirmed by NRP-1 knockdown leading to impaired cancer cell proliferation, blocked cell cycle, reduced cell migration, and reduced focal adhesion kinase expression[ 105 ]. In line with that finding, NRP-1 overexpression in intrahepatic CCA cells that was associated with miR-320a downregulation boosted cell proliferation and epithelial to mesenchymal transition and stimulated tumor angiogenesis[ 106 ]. Recently, high NRP-1 expression was correlated with poor prognosis and reduced overall survival of intrahepatic CCA patients[ 107 ].…”

Impaired AGO2/miR-185-3p/NRP1 axis promotes colorectal cancer metastasis

“…We performed integrated RNA-seq and proteomic analyses and found that AGO2 knockdown led to the upregulation of NRP1, not only at the mRNA level but also at the protein level in multiple CRC cells. NRP1 is well recognized as a key molecule in the process of cancer invasion and metastasis, and its overexpression has been detected in various metastatic tumors 35 , 36 , 40 . Importantly, EMT in CRC might be NRP1-dependent 41 .…”

MicroRNA 320, an Anti-Oncogene Target miRNA for Cancer Therapy

“…Transcriptional regulation and epigenetic modification are two significant mechanisms that control miRNA expression [ 57 , 64 , 100 , 101 ]. As the miR-320 family acts as a tumor repressor has attracted increasing interest in many human tumors, and transforming the tumor suppression signal from miR-320 may be a new strategy to treat cancers in the future.…”

“…The regulation mechanisms for miR-320 expression have been studied in several cell types, and some pivotal TFs were demonstrated to be relevant to this process. A recent study reported that lncRNA TTN-AS1 was able to downregulate hsa-miR-320a-3p through post-transcriptional regulation in cholangiocarcinoma cells, which depended on the Ago2 pathway [ 64 ]. E2A can realize self-regulation as a transcription factor in the process of accelerating the disease progression of CRC cells [ 101 ].…”