Supplementary Material for: Putative Biomarker Genes for Grading Clear Cell Renal Cell Carcinoma

Objective: The initial objective of this renal cancer study
was to identify gene sets in clear cell renal cell carcinoma (ccRCC) to
support grading of ccRCC histopathology. Materials and Methods:
Preselected ccRCC tumor tissues of grade 1 (G1, n = 14) and grade 3 (G3,
n = 15) as well es 14 normal kidney tissues thereof were subjected to
microarray expression analysis using Human Genome U133 Plus 2.0 Array.
Event ratio scoring, hierarchical clustering and principal component
analysis were used to determine gene sets that distinguish expression
profiles from normal kidney tissue, G1 and G3 tumor tissues. Results:
An initial set of 73 genes provided seven gene subclusters (SC01 to
SC07) that distinguish RNA expression profiles from G1, G3 tumor and
normal kidney tissues. A ranked list of 24 genes was determined that
separated G1 from G3 tumors in high concordance with histopathological
grading confirmed by immunohistochemical analysis of ceruloplasmin
protein expression. Conclusion: A final set of 24 genes has been
determined awaiting further validation on the RNA as well as on the
protein level by studying an additional cohort of ccRCC patients. A
reliable separation of G1 and G3 tumor grades will be instrumental to
foster and direct the administration of upcoming targeted therapeutics
of ccRCC tumors in a more predictive and reliable manner.