Bestrophin-4 relays HES4 and interacts with TWIST1 to suppress epithelial-to-mesenchymal transition in colorectal cancer cells.

Abstract

Bestrophin isoform 4 (<i>BEST4</i>) is a newly identified subtype of the calcium-activated chloride channel family. Analysis of colonic epithelial cell diversity by single-cell RNA-sequencing has revealed the existence of a cluster of <i>BEST4</i>+ mature colonocytes in humans. However, if the role of <i>BEST4</i> is involved in regulating tumour progression remains largely unknown. In this study, we demonstrate that <i>BEST4</i> overexpression attenuates cell proliferation, colony formation, and mobility in colorectal cancer (CRC) in vitro, and impedes the tumour growth and the liver metastasis in vivo. BEST4 is co-expressed with hairy/enhancer of split 4 (<i>HES4</i>) in the nucleus of cells, and HES4 signals <i>BEST4</i> by interacting with the upstream region of the <i>BEST4</i> promoter. <i>BEST4</i> is epistatic to <i>HES4</i> and downregulates TWIST1, thereby inhibiting epithelial-to-mesenchymal transition (EMT) in CRC. Conversely, knockout of BEST4 using CRISPR/Cas9 in CRC cells revitalises tumour growth and induces EMT. Furthermore, the low level of the <i>BEST4</i> mRNA is correlated with advanced and the worse prognosis, suggesting its potential role involving CRC progression.