Assessment of gene expression profile by cDNA microarray analysis.

With the advent of cDNA microarray technology, variations in cellular transcriptional events can now be monitored simultaneously, and expression profile at each functional state can be established and compared to one another. Here we illustrate gene expression profile analysis of a cisplatin-resistant ovarian carcinoma cell line (A2780CP)and its parental A2780 cell line, and compare them to assess changes in gene expression related to resistance to cisplatin. Equal quantities(1 μg)of RNA from the cell lines are reverse-transcribed, labeled with P radioisotpe, and hybridized to ovary specific GeneFilters carrying more than 5,000 genes(GF223; Research Genetics, Huntsville, AL). Filter images are recorded by a phosphor-imager and analyzed comparatively using Pathways 3.0 software(Research Genetics). The upregulated and downregulated genes in cisplatin-resistant cells are identified and changes in selected genes are validated by a semiquantitative RT-PCR. This approach allows us to identify groups of genes, rather than just single genes, involved in a process, and can indicate which molecular and cellular events might be critical in such complex biological processes.