B7-H3 promotes the migration and invasion of colorectal cancer cells via regulating the actin cytoskeleton and RhoA/ROCK1/LIMK1 signaling pathway.

Background And Aims: Aberrant expression of B7 homolog 3 protein (B7-H3) has been detected in various cancers including colorectal cancer (CRC) and implicated in modulating multiple biological functions of CRC cells. However, its role in CRC metastasis has not yet been determined. This study aims to explore and unravel the underlying mechanisms through which B7-H3 contributes to migration, invasion and actin cytoskeleton in CRC.

Methods: The expression of B7-H3 and LIMK1 in CRC tumor samples was determined by IHC staining. Transwell and F-actin immunofluorescence staining assays were performed to explore the role of B7-H3 in migration, invasion and actin filament accumulating of CRC cells. RNA-seq and Western blot assays were used to investigate the molecular mechanisms.

Results: B7-H3 was highly expressed in CRC tissues and positively associated with poor prognosis of CRC patients by immunohistochemistry. Migration and invasion assays showed that B7-H3 knockdown significantly inhibited the migration and invasion of CRC cells. B7-H3 overexpression had the opposite effect. Moreover, we determined that B7-H3 could regulate actin cytoskeleton and the RhoA/ROCK1/LIMK1 pathway by F-actin immunofluorescence staining and Western blot. Importantly, the BDP5290, an inhibitor of the RhoA/ROCK1/(LIM domain kinase 1) LIMK1 axis, reversed the effects of B7-H3 overexpression on actin filament accumulating, migration, and invasion of CRC cells.

Conclusions: Our study concluded that B7-H3 facilitated CRC cell actin filament accumulating, migration, and invasion through the RhoA/ROCK1/LIMK1 axis.