Measurements of human papillomavirus transcripts by real time quantitative reverse transcription-polymerase chain reaction in samples collected for cervical cancer screening.

Specific assays capable of distinguishing normal and atypical cervical changes from pre-cancerous lesions are direly needed to improve screening for cervical cancer. Specific genes transcripts that are up-regulated in dysplastic and cancer cells can be exploited as new markers for cervical cancer screening provided that they can be detected in heterogeneous populations such as those collected for Papanicolaou tests. We hypothesized that expression of the HPV early region gene E7 might distinguish between normal samples (absent expression) and high-grade lesions (detectable E7 expression). Our goal was to detect and measure gene expression in cells scraped from the cervix using real time quantitative reverse transcription-polymerase chain reaction (TaqMan). We have optimized collection and extraction procedures to provide suitable RNA for TaqMan analysis in clinical samples collected for cervical cancer screening and have demonstrated efficient measurements of housekeeping genes in these samples. HPV 16 or 18 early gene E7 transcripts were detected in 47% of samples with a clinical diagnosis of high-grade SIL and in 0% of cytologically normal samples (P = 0.006). Our study demonstrates that the TaqMan assay can be reliably applied to samples collected for cervical cancer screening, and that presence of detectable HPV E7 transcripts can distinguish between normal and abnormal samples.