Amplification and overexpression of Elongin C gene discovered in prostate cancer by cDNA microarrays

Functional significance of several oncogenes is mediated by overexpression. To identify overexpressed genes in prostate cancer, we analyzed expression of 1081 transcripts in three prostate cancer cell lines (PC-3, DU145, and LNCaP) using cDNA microarray hybridization. The cDNA microarray analyses were validated by quantitative real-time RT-PCR. On average, 64% of the genes were expressed at detectable levels in the cell lines. Next, the expression profiles were combined with the data on DNA sequence copy number alterations in the cell lines obtained by comparative genomic hybridization. The genes for Elongin C and urokinase type plasminogen-activator, both located in the regions of amplification in the PC-3 cell line (8q21 and 10q22, respectively), were found to be overexpressed in the PC-3. Amplification and overexpression of urokinase type plasminogen-activator in prostate cancer has previously been reported. Here, fluorescence in situ hybridization on tissue microarray showed high-level amplification of the Elongin C gene in 8 (23%) of 35 hormone-refractory carcinomas but in none of the untreated prostate carcinomas (n = 35). Finally, it was shown that the Elongin C gene was overexpressed and amplified also in breast cancer cell line SK-Br-3. The results indicate that Elongin C is a putative target gene for 8q amplification.