Recent studies suggest a role of the proteasome activator, REGgamma, in cancer progression. Since there are limited numbers of known REGgamma targets, it is not known which cancers and pathways are associated with REGgamma.

REGgamma protein expressions in four different cancers were investigated by immunohistochemistry (IHC) analysis. Following NCBI Gene Expression Omnibus (GEO) database search, microarray platform validation, differential expressions of REGgamma in corresponding cancers were statistically analyzed. Genes highly correlated with REGgamma were defined based on Pearson's correlation coefficient. Functional links were estimated by Ingenuity Core analysis. Finally, validation was performed by RT-PCR analysis in established cancer cell lines and IHC in human colon cancer tissues.

Here, we demonstrate overexpression of REGgamma in four different cancer types by micro-tissue array analysis. Using meta-analysis of publicly available microarray databases and biological studies, we verified elevated REGgamma gene expression in the four types of cancers and identified genes significantly correlated with REGgamma expression, including genes in p53, Myc pathways, and multiple other cancer-related pathways. The predicted correlations were largely consistent with quantitative RT-PCR analysis.

This study provides us novel insights in REGgamma gene expression profiles and its link to multiple cancer-related pathways in cancers. Our results indicate potentially important pathogenic roles of REGgamma in multiple cancer types and implicate REGgamma as a putative cancer marker.

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