Tissue microarray profiling of cancer specimens and cell lines: Opportunities and limitations

The implementations of high-throughput genetic technologies, such as oligon ucleotide microarrays, generate myriad points of data. The identified poten tial candidate genes need to be further characterized and selected using a large number of well-characterized tumors and stringent criteria. Tissue mi croarrays allow for such high-throughput expression profiling of tumor samp les, providing, in addition, information at the microanatomical level. Diff erent techniques could be applied for identification of specific phenotypic (immunohistochemistry and in situ hybridization) or genotypic (fluorescenc e in situ hybridization) alterations, holding strong potential for translat ional research. Tissue microarrays consisting of 0.6-mm biopsies of paraffi n-embedded tissues are well validated and have been used for various clinic opathological studies. This review discusses the technical considerations f or construction of such arrays from paraffin-embedded tissues and cell line s and outlines their potential for clinical research applications. The use of paraffin-embedded tissues has some limitations with regard to analysis o f RNA or certain proteins, To overcome such limitations, we have developed a cryoarray strategy allowing for the processing of multiple frozen tissue specimens and/or cell lines on a single tissue block. These approaches offe r the opportunity to conduct pilot and validation studies of potential targ ets using clinical samples linked to clinicopathological databases.