ThinPrep-processed fine-needle samples of breast are effective material for RNA- and DNA-based molecular diagnosis: application to p53 mutation analysis.

Background: Fine-needle sampling is the least invasive method of in vivo breast carcinoma sampling and can provide material for breast carcinoma diagnosis. The aim of the current study was to assess the accuracy of molecular diagnosis techniques using fine-needle sample (FNS) material stored in PreservCyt (Cytyc Corp., Boxborough, MA).

Methods: The p53 tumor suppressor gene was chosen as a model because it can be used for DNA, RNA, and protein analysis. Molecular analysis was performed using a yeast functional assay and DNA sequencing. p53 accumulation was evaluated by immunocytochemistry.

Results: DNA and protein analysis indicated that samples stored for periods of several months, either at room temperature, 4 degrees C, or -20 degrees C, can be processed reliably. For RNA-based diagnosis, samples were still intact after 5 months of storage in PreservCyt at 4 degrees C. In addition, using FNS material that was stored for 16 months at 4 degrees C, the authors detected p53 mutations with either the functional assay for separating alleles in yeast (an RNA-based functional assay) or direct cDNA sequencing.

Conclusions: Fine-needle samples stored in PreservCyt at 4 degrees C are very good material for molecular diagnosis techniques. In addition, it is feasible to adopt a strategy of storing excess FNS material to create cellular banks that will be invaluable for future gene studies.