In Situ Hybridization in Cancer and Normal Tissue

Abstract

With recent advances in the Human Genome Project and progress in microarray and gene chip technology, an explosion of genomic information is becoming available. One of the major ways to understand this vast amount of data is by bestowing topological information to help us identify the functional relevance of specific genes and to explain the pathogenesis of disease processes. In situ hybridization is a technique that will further our understanding of the function of genes within normal tissue along with the pathogenesis of a disease process within abnormal cells. This chapter provides an overview of in situ hybridization, followed by general principles and protocols. In situ hybridization is a molecular technique to localize nucleic acid sequences in chromosomes, cell populations, or morphologically preserved tissue sections. The power of this technique lies in the fact that nucleic acid detection can be accomplished in the context of chromosomal, cellular, or tissue morphology and hence localization can be achieved to a specific chromosome, cellular population, or a specific location within a tissue. This localization is important to derive, for instance, the deletion or amplification of a particular portion of chromosome and the functional relevance of the expression of a specific gene or to identify target cells infected by a virus. Such spatial information may be critical to understand the function of genes within a normal tissue and the pathogenesis of a disease process. Other methods to identify nucleic acids include solution hybridization and general polymerase chain reaction (PCR)-based methods in which tissues or cells are homogenized before analysis. Although these methods identify the presence of a specific nucleic acid, they do not provide information about the localization of the signal to specific cell populations in relation to tissue morphology. Sensitivity of in situ hybridization has markedly improved in recent years because of better probe labeling methods and signal amplification detection systems, to the extent that very few copies of target nucleic acid can be routinely detected