Abstract
Background
Tumor metastasis has been regarded as the leading risk factor for tumor patients. BEN-domain (BEND) family proteins have not been well elucidated in tumor metastasis.
Methods
To uncover the roles of BEND family proteins (BEND2-7) in colorectal cancer (CRC), we first mined their mRNA expression in both tumor and normal tissues from CRC patients, and plotted the survival curve. Through in vitro cell migration, invasion and in vivo tumor metastasis experiments, we confirmed that BEND3 acted as a tumor suppressor by dampening CRC-liver metastasis. Using RNA sequencing, we profiled the BEND3-targeted genes. To explore the mechanism how BEND3 represses target genes, an immunoprecipitation-mass assay was applied to reveal BEND3-interacting proteins.
Results
We speculated BEND3 as a candidate suppressor for CRC-liver metastasis using datamining. RNA-profiling showed BEND3 downregulated genes which partially enriched in two KEGG pathways: extracellular matrix organization and focal adhesion. MMP9 and CLDN18, as the representative genes for extracellular matrix organization and focal adhesion, respectively, were ascertained to be upregulated in BEND3-depleted cells. We then identified HDAC1 as a potential interactor of BEND3 and the upstream signal FGF2/FGFR2 which could disrupt BEND3/HDAC1 axis depending on FGFR2-mediated phosphorylation of BEND3 at Y153 and then trigger an activated chromatin state on the enhancer of MMP9 and CLDN18. Finally, the phosphorylation of BEND3 at Y153 positively correlates with MMP9 and CLDN18 and predicts a worse prognosis for CRC patients.
Conclusions
This is the first study that reveals the suppressive role of BEND3 in CRC and our results has preliminarily established it as a prognostic biomarker and a potential target in CRC-liver metastasis.