Diverse roles of C-terminal Hsp70-interacting protein (CHIP) in tumorigenesis.

BACKGROUND: The carboxyl terminus of Hsp70-interacting protein (CHIP) is a member of E3 ubiquitin ligase, functioning as a link between the chaperone (heat shock protein 70/90) and proteasome systems, playing a vital role in maintaining the protein homeostasis in the cytoplasm. CHIP has been demonstrated to be involved in tumorigenesis, proliferation and invasion in several malignancies, regulating a number of oncogenic proteins. However, CHIP has also been implicated in the modulation of tumor suppressor proteins. The pathogenic mechanism of CHIP expression in human malignancy is not yet clear, and a number of studies have suggested that CHIP may have opposing roles in different cancers. Therefore, many studies have focused on the relationship between CHIP and carcinoma.
METHODS: A literature search focusing on regulation network, biological function and clinical significance of CHIP in connection with its role in cancer development was performed on the MEDLINE databases. RESULTS AND
CONCLUSIONS: CHIP may be a potential diagnostic biomarker and therapeutic target for human cancer, and may play different roles in different human cancers. This inconsistence might be induced by the diversity of CHIP downstream targeting proteins. Therefore, the phenotypes determined by CHIP should be dependent on the function of its specific targets in a specific type of cancer cells. Whether CHIP contributes to tumor progression or suppression in various human cancers remains unclear, suggesting the necessity of further extensive investigation of its role in tumorigenesis.