ANALYSIS OF DIFFERENTIAL GENE-EXPRESSION IN HUMAN COLORECTAL TUMOR-TISSUES BY RNA ARBITRARILY PRIMED-PCR - A TECHNICAL ASSESSMENT

RNA arbitrarily primed (RAP)-PCR is a powerful tool for studying diffe rential gene expression in cancer cells. Systematic analysis of human tumor samples may provide a list of markers with potential application to the diagnosis, prognostic assessment, and treatment of the disease . Nevertheless, because of characteristics inherent to the samples and technique, artifactual results are likely. We have assessed the effec ts of several factors on RAP-PCR performance to determine the sensitiv ity and reproducibility of the technique, as well as the accuracy of i ts results, under different conditions in human cell lines and in a se ries of 129 paired human normal colonic mucosa-colorectal carcinoma sa mples. Our results show that RAP-PCR provides reliable fingerprints in a relatively wide spectrum of circumstances, including variations in RNA concentration and contamination by DNA. Densitometric analysis ind icated that relative band-intensity variations more than 20% were repr oducible in 95% of the cases. Serial analysis of paired normal-tumor c ases yielded a number of bands that were recurrently either underexpre ssed or overexpressed in tumor relative to normal mucosa. These differ entially expressed bands are prime targets of research because they re present candidate tumor-specific up- or down-regulated genes with a re levant role in carcinogenesis.