Molecular quality of exfoliated cervical cells: implications for molecular epidemiology and biomarker discovery

The biologic sample collected in molecular epidemiology studies must accurately reflect the disease being studied and have sufficient molecular quality for the intended assays. Noninvasive sampling methods, such as scrapes or brushes, are increasingly used. In this study, we evaluate the impact of sample collection media and extraction methods on the quality and yield of RNA from routine exfoliated cervical cytology. Excess cellular material remaining on the cytologic collection device after preparation of the routine screening Papanicolaou smear was placed in a variety of collection media and extracted using two commercial kits. The collection media had the largest impact on the yield and quality of RNA as evaluated by denaturing agarose gel electrophoresis and image analysis. Two collection media, PAXgene and PreservCyt, yielded RNA from most samples. The RNA showed some degree of degradation as evidenced by the reduced size of the higher molecular weight ribosomal band. However, with a sensitive gold particle-based detection method, reproducible microarray results were obtained using this RNA.