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

The implementations of high-throughput genetic technologies, such as oligonucleotide microarrays, generate myriad points of data. The identified potential candidate genes need to be further characterized and selected using a large number of well-characterized tumors and stringent criteria. Tissue microarrays allow for such high-throughput expression profiling of tumor samples, providing, in addition, information at the microanatomical level. Different techniques could be applied for identification of specific phenotypic (immunohistochemistry and in situ hybridization) or genotypic (fluorescence in situ hybridization) alterations, holding strong potential for translational research. Tissue microarrays consisting of 0.6-mm biopsies of paraffin-embedded tissues are well validated and have been used for various clinicopathological studies. This review discusses the technical considerations for construction of such arrays from paraffin-embedded tissues and cell lines and outlines their potential for clinical research applications. The use of paraffin-embedded tissues has some limitations with regard to analysis of 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 offer the opportunity to conduct pilot and validation studies of potential targets using clinical samples linked to clinicopathological databases.