Expression profiling of cervical cancer biopsies using high-resolution dual-label imaging of ³³P and ³H on microarrays

To identify gene clusters that are involved in the development and progression of cervical cancer we hybridized biopsy material to a custom microarray. Since only small amounts of RNA can be isolated from biopsy material we applied a detection system that is more sensitive than fluorescence detection. The approach combines the advantages of competitive hybridization with the high sensitivity of radioactivity on a microarray platform. Instead of using two fluorescent dyes for labeling we co-hybridized ³³P- and ³H-labeled probes to our microarray. For the simultaneous detection of the two isotopes we used a new technology that allows the detection of radioactivity in real time with very high resolution (10 μm). The unique features of the instrument are a high detection sensitivity for ³³P and ³H and an infinite linear range of detection. To select the genes on the array we made use of public gene expression data generated in the past few years (approximately 2,000 clones). In addition to the genes selected from the literature, we added genes obtained from complementary DNA representational difference analysis experiments (approximately 5,000 clones).