Ebp1在肿瘤增殖和侵袭中的研究进展

肿瘤细胞的恶性增殖和浸润转移是影响肿瘤发展和治疗效果的重要因素,了解调控增殖和转移的影响因子及其分子机制对肿瘤早期的诊断和临床治疗意义重大。本文系统总结了增殖相关蛋白PA2G4（proliferation associated 2G4）家族成员Ebp1在多种肿瘤中的表达情况及其对细胞周期、细胞凋亡和分化、细胞迁移等方面的影响,并归纳了Ebp1影响肿瘤增殖和迁移的分子机制。Ebp在多种肿瘤中表达降低且与肿瘤的增殖和迁移呈负相关,并主要通过抑制周期相关蛋白的转录、调控影响肿瘤发展的信号通路。      

Opposing roles of the two isoforms of ErbB3 binding protein 1 in human cancer cells

The different functions of the two isoforms of ErbB3 binding protein 1 (Ebp1), p48 and p42, have recently become the focus of interest as they reveal contradictory roles in cell growth promoting ability. The conformational change that crystal structure of p42 was shown to lack α helices at the amino‐terminus present in p48 represents the differential binding partners and protein modifications of two Ebp1 isoforms. N‐terminal specific phosphorylation by CDK2 and deregulation of the p53 tumor suppressor through specific interaction with HDM2 and Akt activation is postulated to contribute to p48‐mediated tumorigenesis. The short isoform p42 Ebp1, which is actual binding partner of ErbB3 has been implicated as a tumor suppressor with many binding partners such as Rb, HDAC2, Sin3A and the p85 subunit of PI3K with HSP70/CHIP, inhibiting its own antiproliferative activity or inhibiting PI3K activity. The aim of the current review is to provide a summary on distinctive cellular functions of two Ebp1 proteins and their molecular partners that might be responsible for the unique functions of each isoform of Ebp1.     

Che-1 affects cell growth by interfering with the recruitment of HDAC1 by Rb

DNA tumor virus oncoproteins bind and inactivate Rb by interfering with the Rb/HDAC1 interaction. Che-1 is a recently identified human Rb binding protein that inhibits the Rb growth suppressing function. Here we show that Che-1 contacts the Rb pocket region and competes with HDAC1 for Rb binding site, removing HDAC1 from the Rb/E2F complex in vitro and from the E2F target promoters in vivo. Che-1 overexpression activates DNA synthesis in quiescent NIH-3T3 cells through HDAC1 displacement. Consistently, Che-1-specific RNA interference affects E2F activity and cell proliferation in human fibroblasts but not in the pocket protein-defective 293 cells. These findings indicate the existence of a pathway of Rb regulation supporting Che-1 as the cellular counterpart of DNA tumor virus oncoproteins.