Signet-ring cell carcinoma (SRCC) is a unique subtype of gastric cancer that is impaired for cell-cell adhesion. The pathogenesis of SRCC remains unclear. Here
we show that expression of kinesin-associated protein 3 (KAP3)
a cargo adaptor subunit of the kinesin superfamily protein 3 (KIF3)
a motor protein
is specifically decreased in SRCC of the stomach. CRISPR/Cas9-mediated gene knockout experiments indicated that loss of KAP3 impairs the formation of circumferential actomyosin cables by inactivating RhoA
leading to the weakening of cell-cell adhesion. Furthermore
in KAP3 knockout cells
post-Golgi transport of laminin
a key component of the basement membrane
was inhibited
resulting in impaired basement membrane formation. Together
these findings uncover a potential role for KAP3 in the pathogenesis of SRCC of the stomach.