Rol e of Mi cro array in Ca ncer Di agno sis

Although DNA micro-array analysis for tumor diagnosis and classification is a promising diagnostic modality for the future, currently, there are many limitations. First of all, accurate diagnoses of individual tumors by gene expression profile alone are not always possible. This may be because no reference databases for comprehensive gene expression for cancer has been explored, and no specific group of biomarkers for the diagnosis of specific tumors have yet been developed. Secondly, the gene expression data shows remarkable variations within the same tumor. This may result from different gene expression profiles in the tumors and the different peritumoral lymphoid or stromal reaction status. Thirdly, early tumor detection is not possible by the gene expression profile. Currently, cancer diagnosis with the DNA micro-array is possible only when large amounts and high fractions of tumor cells are prepared. Detection of the membrane protein fragments or specific mutations in circulating tumor cells from body fluids is more effective and a popular approach in the early detection of tumors. The analysis of cancer specific mRNAs from body fluids containing tumor cells is another promising way; however, this can be more effectively carried out by RT-PCR (20,21) han by DNA micro-array. In spite of these limitations, DNA microarray can be best used for molecular classification based on genetic and biological changes. In this month's issue, Bae et al (22). reported gene expression profiling of uterine leiomyomas. The authors analyzed the gene expression profiles of leiomyomas by using the cDNA micro-array. They compared the gene expression profile of leiomyomas to that of normal myometrium and found 21 upregulated and 50 down-regulated genes. Interestingly, most of the up-regulated genes were ones known to have nucleic acid binding activity. This study is a good model for the evaluation of genes involved in multi-step carcinogenesis. The uterine myometrium is mostly composed of homogeneous myometrial cells, and leiomyoma is also a homogeneous tumor originating from myometrial cells. Moreover, leiomyosarcoma is another homogeneous mesenchymal tumor originating from myometrial cells, thus eliminating the heterogeneous peritumoral reaction. This unusual homogeneity of research materials enables one to find many valuable target genes by expression proteomics analysis. It has been reported that DNA micro-array analysis can be a new method for the classification of soft tissue tumors (14). This method can further improve the method based on histolo