Abstract
Inactivation of HSP90 and HSP70 leads to loss of invasion in a variety of cancer cell types, presumably as a result of destabilization of, as yet, undefined clients of these molecular chaperones that influence this phenotype. The WASF3 gene has been shown to be up-regulated in high-grade tumors and its down-regulation leads to loss of invasion and metastasis. WASF3 phosphorylation by ABL kinase is essential for its ability to regulate invasion. Mass spectroscopy analysis now shows that HSP90 is present in the WASF3 immunocomplex from prostate cancer cells. Inactivation of HSP90 in these and other cell types does not affect WASF3 stability but prevents its phosphoactivation as a result of destabilization of ABL. HSP70 was also found in the WASF3 immunocomplex and inactivation of HSP70 results in destabilization of WASF3 through proteasome degradation. Knockdown of WASF3, HSP90, and HSP70 individually, all lead to loss of invasion but as knockdown of WASF3 in the presence of robust expression of HSP90/70 has the same effect, it seems that the influence these chaperone proteins have on invasion is mediated, at least in part, by their control over the critical invasion promoting capacity of the WASF3 protein. Overexpression of HSP70 in WASF3 null cells does not enhance invasion. These observations suggest that targeting HSP90/70 may have efficacy in reducing cancer cell invasion.
Highlights
HSP90/70 inactivation reduces cancer cell invasion by unknown mechanisms
WASF3 Interacts with HSP90—To identify proteins that interact with WASF3, an exogenous HA-tagged WASF3 gene was expressed in PC3 prostate cancer cells, and immunocomplexes were isolated using an anti-HA antibody
The MS analysis identified HSP90 in the immunocomplex (Fig. 1A), which was confirmed using IP and Western blotting with either the HA antibody to immunoprecipitate the exogenous WASF3 (Fig. 1B) or a WASF3-specific antibody to immunoprecipitate the endogenous protein (Fig. 1C). These results demonstrate that the interaction between WASF3 and HSP90 is not specific to a system in which WASF3 is overexpressed
Summary
Results: The WASF3 metastasis promoting gene stability and activation is regulated by HSP90/70 chaperones. Inactivation of HSP90 and HSP70 leads to loss of invasion in a variety of cancer cell types, presumably as a result of destabilization of, as yet, undefined clients of these molecular chaperones that influence this phenotype. The WASF3 gene has been shown to be up-regulated in high-grade tumors and its downregulation leads to loss of invasion and metastasis. Inactivation of HSP90 in these and other cell types does not affect WASF3 stability but prevents its phosphoactivation as a result of destabilization of ABL. Overexpression of HSP70 in WASF3 null cells does not enhance invasion. These observations suggest that targeting HSP90/70 may have efficacy in reducing cancer cell invasion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
