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Modified p27 Kip1 is efficient in suppressing HER2‐mediated tumorigenicity
Author(s) -
Yang HengYin,
Yang Huiling,
Zhao Ruiying,
Lee MongHong
Publication year - 2006
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.20762
Subject(s) - cyclin dependent kinase , cancer research , chemistry , cyclin dependent kinase 2 , microbiology and biotechnology , cell growth , ubiquitin , kinase , cell cycle , biology , protein kinase a , cell , gene , biochemistry
Cyclin‐dependent kinase (CDK) inhibitor p27 Kip1, a haplo‐insufficient tumor suppressor, is downregulated by oncogenic signal of HER2, a receptor tyrosine kinase oncogene. HER2 promotes mitogenic growth and transformation of cancer cells. HER2 signaling can enhance p27 Kip1 ubiquitination, thereby promoting p27 degradation and subsequent activation of CDK activity. p27 ubiquitination and degradation is enhanced by JAB1 binding as well as by phosphorylation on Thr187. In this study, we generated modified p27 proteins, which are mutated at Thr 187 or deleted at JAB1 binding domain. We applied these modified p27 genes as novel anticancer agents for HER2‐overexpressing cells under the control of a tetracycline (tet)‐regulated gene expression system. Induction of p27 T187A and p27 T187A ΔJAB inhibits HER2‐activated cell growth, CDK2 activity, cell proliferation, and transformation. Significantly, a modified protein (p27 T187AΔJAB) reduced the tumor volume in a HER2‐overexpressing tumor model efficiently. These findings demonstrate the applicability of employing modified p27 proteins as a therapeutic intervention in HER2‐overexpressing cancers. J. Cell. Biochem. 98: 128–138, 2006. © 2005 Wiley‐Liss, Inc.