Detection of chromosome changes in pathology archives:: an application of microwave-assisted fluorescence in situ hybridization to human carcinogenesis studies

Pathology archives provide unique and abundant opportunities to investigate human carcinogenesis and identify potential targets for cancer therapy. Microwaving was introduced into various procedures used in histopathology two decades ago, although the precise mechanisms underlying its effectiveness in any of the procedures, including antigen retrieval, acceleration of fixation and nucleic acid hybridization, are not known. Since microwaving was first applied to fluorescence in situ hybridization (FISH), many pathologists and researchers have enjoyed the benefits of excellent preservation of histological structures as well as good retrieval of FISH signals by this method. Microwave-assisted fluorescence in situ hybridization (MW-FISH) has proved to be especially useful in retrospective investigations of tissues fixed and preserved for long periods of time, and the success rates in the randomly selected pathology archives have been greater (70-95%) than by the conventional protocol (<= 40%) The MW-FISH protocol and current availability of human genome information together with information on a variety of other histopathological attributes have paved the way to exploration of specific, large-scale genomic changes in human tumor tissue, even in the incipient stage. In practice, this protocol is very useful for retrospective surveillance of amplicons in tumor tissue by using hundreds of bacterial artificial chromosome clones and many specimens in the form of a tissue microarray. Effective retrieval of specific genome-wide amplicon profiles from human tumors stored unaware in ordinary pathology laboratories would help to further stratify tumors so that individually tailored treatment strategies would become feasible in clinical settings.