DNA Microarrays for Analysis of Gene Expression

Transformation of the prostatic epithelium is accompanied by changes in the expression of many genes, as reflected in altered steady-state levels of the mRNAs derived from them. The acquisition of androgen independence is likewise accompanied by changes in gene expression. Using DNA microarray technology, it is now possible to measure the levels of thousands of different mRNAs in a single hybridization step. This technique is particularly powerful for comparing gene expression in the same tissue under different environmental conditions; for example, comparing mRNA levels in malignant cells growing in the presence or absence of a hormone such as testosterone. Sufficient cDNA for hybridization to a microarray can be produced from as little as 1 mg of tissue. Coupled with DNA sequence information emerging from the Human Genome Project, this technique has the potential to rapidly identify genes that are differentially expressed in situations with direct relevance to prostate cancer. It is reasonably likely that diagnostic patterns of gene expression can be found for normal v benign proliferative malignant prostatic epithelium, androgen-dependent v androgen-independent tumors, and drug-sensitive v drug-resistant tumors. Once identified, informative cDNAs can be included in diagnostic microarrays with potential for clinical application.