Identification of a novel 14-3-3 β binding partner and its functional analysis in aflatoxin B₁-induced rat hepatoma K2 cells

Abstract

We previously reported that 14-3-3 β mRNA is overexpressed as well as c-myc mRNA in aflatoxin B₁ (AFB₁)-induced rat hepatoma K2 cells and 14-3-3 β plays a crucial role in abnormal growth of K2 cells. The 14-3-3 family proteins are involved in important cellular processes such as signal transduction, cell cycle control, apoptosis and malignant transformation. The 14-3-3 proteins bind to phosphorylated form of proteins and a large number of their binding partners have been reported. Here, we isolated a novel binding partner of 14-3-3 β by yeast two-hybrid screening using 14-3-3 β as a bait, and it was termed fourteen-three-three beta interactant 1(FBI1). FBI1 mRNA was strongly expressed in K2 cells as compared with the normal rat liver tissue. Furthermore expression of antisense FBI1 RNA significantly suppressed anchorage-indepandent growth of K2 cells as a hallmark of tumor cells in vitro. These results suggest that FBI1 implicates in abnormal growth of K2 cells through the cooperation with 14-3-3 β.