Data from Oncogenic Function of SCCRO5/DCUN1D5 Requires Its Neddylation E3 Activity and Nuclear Localization

Abstract

<div>Abstract<p><b>Purpose:</b> To determine mechanisms by which <i>SCCRO5</i> (aka <i>DCUN1D5</i>) promotes oncogenesis.</p><p><b>Experimental Design:</b><i>SCCRO5</i> mRNA and protein expression were assessed in 203 randomly selected primary cancer tissue samples, matched histologically normal tissues, and cell lines by use of real-time PCR and Western blot analysis. <i>SCCRO5</i> overexpression was correlated with survival. The effect of <i>SCCRO5</i> knockdown on viability was assessed in selected cancer cell lines. Structure–function studies were performed to determine the SCCRO5 residues required for binding to the neddylation components, for neddylation-promoting activity, and for transformation.</p><p><b>Results:</b> In oral and lung squamous cell carcinomas, <i>SCCRO5</i> mRNA levels corresponded with protein levels and overexpression correlated with decreased disease-specific survival. Knockdown of <i>SCCRO5</i> by RNAi resulted in a selective decrease in the viability of cancer cells with high endogenous levels, suggesting the presence of oncogene addiction. SCCRO5 promoted cullin neddylation while maintaining conserved reaction processivity paradigms involved in ubiquitin and ubiquitin-like protein conjugation, establishing it as a component of the neddylation E3. Neddylation activities <i>in vitro</i> required the potentiating of neddylation (PONY) domain but not the nuclear localization sequence (NLS) domain. In contrast, both the NLS domain and the PONY domain were required for transformation of NIH-3T3 cells.</p><p><b>Conclusions:</b> Our data suggest that <i>SCCRO5</i> has oncogenic potential that requires its function as a component of the neddylation E3. Neddylation activity and nuclear localization of SCCRO5 are important for its <i>in vivo</i> function. <i>Clin Cancer Res; 20(2); 372–81. ©2013 AACR</i>.</p></div>