Identification of a novel transcript up-regulated in a clinically aggressive prostate carcinoma

Objectives. To identify differentially expressed genes in tumor cells of patients with prostate cancer by means of tissue microdissection and targeted differential display. Methods. RNA was recovered from pure populations of microdissected normal epithelium and invasive tumor from frozen tissue sections of a radical prostatectomy specimen. Reverse transcription- polymerase chain reaction (PCR) using arbitrary and zinc finger PCR primers was performed. Results. A 130-base pair product was identified that appeared selectively in the tumor sample. DNA sequence analysis revealed it to be a clone from the expressed sequence tag database (GenBank accession R00504). Microdissection of normal epithelium and the corresponding invasive tumor was subsequently performed on a test panel of 10 prostate carcinoma specimens. Comparison of R00504 levels in normal epithelium and invasive carcinoma, using beta-actin as an internal control, showed the transcript to be substantially over expressed in 5 of 10 carcinomas. Northern blotting revealed R00504 to be a 2.6-kilobase gene. Conclusions. A novel transcript up-regulated in an aggressive prostate carcinoma was identified using degenerate zinc finger primers in microdissected tissue samples. The approach used in this study may be helpful in quantitative comparison of known genes and identification of novel genes in microdissected human tissue samples.