Expression in normal human tissues of five nucleotide excision repair genes measured simultaneously by multiplex reverse transcription-polymerase chain reaction

DNA repair is central to the integrity of the human genome. Reduced DNA rep air capacity has been linked to genetic susceptibility to cancer. An adequa te expression level of DNA repair genes is essential for normal DNA repair activities. Although there is tissue specificity in the expression, searchi ng for a surrogate tissue is needled for molecular epidemiological studies. In this study, the relative expression levels of five selected human nucle otide excision repair (NER) genes (ERCC1, XPB/ERCC3, XPG/ERCC5, CSB/ERCC6, and XPC) in 20 different types of human normal tissue were simultaneously m easured by a new multiplex reverse transcription (RT)-PCR assay using the e xpression level of the beta-actin gene as an internal control. Transcripts of each of the five NER genes were detectable, but the levels varied in the se normal tissues. Both mitogen (phytohemagglutinin)-stimulated and unstimu lated human peripheral lymphocytes showed similar expression patterns for t he five NER genes. In general, the expression levels of stimulated lymphocy tes were also similar to most of the rapidly proliferating tissues, such as the skin, breast, intestine, liver, testis, ovary, placenta, or prostate, but was relatively higher than that of the slowly proliferating or nonproli ferating tissues such as adipose, brain, hippocampus, muscle, spleen, or lu ng. The data suggested that although the five NER genes were expressed at d ifferent levels in the normal tissues examined, PHA-stimulated peripheral l ymphocytes may be used as a surrogate tissue for estimating expression leve ls of these genes in proliferating tissues. This new multiplex RT-PCR assay may help detect aberrant.