circEIF3I facilitates the recruitment of SMAD3 to early endosomes to promote TGF-β signalling pathway-mediated activation of MMPs in pancreatic cancer
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Published:2023-09-09
Issue:1
Volume:22
Page:
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ISSN:1476-4598
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Container-title:Molecular Cancer
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language:en
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Short-container-title:Mol Cancer
Author:
Zhao Zhongjie,Yang Wenbo,Kong Rui,Zhang Yangyang,Li Le,Song Zengfu,Chen Hongze,Luo Yan,Zhang Tao,Cheng Chundong,Li Guanqun,Liu Danxi,Geng Xinglong,Chen Hua,Wang Yongwei,Pan Shangha,Hu Jisheng,Sun Bei
Abstract
Abstract
Background
Among digestive tract tumours, pancreatic ductal adenocarcinoma (PDAC) shows the highest mortality trend. Moreover, although PDAC metastasis remains a leading cause of cancer-related deaths, the biological mechanism is poorly understood. Recent evidence demonstrates that circular RNAs (circRNAs) play important roles in PDAC progression.
Methods
Differentially expressed circRNAs in normal and PDAC tissues were screened via bioinformatics analysis. Sanger sequencing, RNase R and actinomycin D assays were performed to confirm the loop structure of circEIF3I. In vitro and in vivo functional experiments were conducted to assess the role of circEIF3I in PDAC. MS2-tagged RNA affinity purification, mass spectrometry, RNA immunoprecipitation, RNA pull-down assay, fluorescence in situ hybridization, immunofluorescence and RNA–protein interaction simulation and analysis were performed to identify circEIF3I-interacting proteins. The effects of circEIF3I on the interactions of SMAD3 with TGFβRI or AP2A1 were measured through co-immunoprecipitation and western blotting.
Results
A microarray data analysis showed that circEIF3I was highly expressed in PDAC cells and correlated with TNM stage and poor prognosis. Functional experiments in vitro and in vivo revealed that circEIF3I accelerated PDAC cells migration, invasion and metastasis by increasing MMPs expression and activity. Mechanistic research indicated that circEIF3I binds to the MH2 domain of SMAD3 and increases SMAD3 phosphorylation by strengthening the interactions between SMAD3 and TGFβRI on early endosomes. Moreover, AP2A1 binds with circEIF3I directly and promotes circEIF3I-bound SMAD3 recruitment to TGFβRI on early endosomes. Finally, we found that circEif3i exerts biological functions in mice similar to those of circEIF3I in humans PDAC.
Conclusions
Our study reveals that circEIF3I promotes pancreatic cancer progression. circEIF3I is a molecular scaffold that interacts with SMAD3 and AP2A1 to form a ternary complex, that facilitates the recruitment of SMAD3 to early endosomes and then activates the TGF-β signalling pathway. Hence, circEIF3I is a potential prognostic biomarker and therapeutic target in PDAC.
Funder
National Natural Science Foundation of China
The China Postdoctoral Science Foundation
The Natural Science Foundation of Heilongjiang Province
The Heilongjiang Province Postdoctoral Science Foundation, Heilongjiang Postdoctoral Scientific Research Developmental Fund
the Heilongjiang Provincial Universities Fundamental Research Funds
Excellent Young Scientific Research Funding Program of the First Affiliated Hospital of Harbin Medical University
Publisher
Springer Science and Business Media LLC
Subject
Cancer Research,Oncology,Molecular Medicine
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