title: The storage period of the formalin-fixed paraffin-embedded tumor blocks does not influence the concentration and purity of the isolated DNA in a series of 83 renal and thyroid carcinomas.
abstract: Optimal recovery of nucleic acids from formalin-fixed paraffin-embedded (FFPE) tissues is highly dependent on a series of pre-extraction steps, mainly related (but not limited) to fixation. The aim of our study was to investigate if the storage period of the FFPE blocks had a significant effect on the isolated DNA. We examined the quantity and purity of the isolated DNA from 83 FFPE blocks, corresponding to malignant thyroid (n=28) and renal (n=55) carcinomas that had been stored in our department for up to eight years. The DNA extraction protocol was based on a precipitation method (MasterPure™ DNA Purification Kit, Epicentre), in accordance to the manufacturer instructions, optimized in our laboratory. A spectrophotometer was used to determine the yield (A260) and purity (A260/A280 ratio) of the isolated DNA. We successfully isolated good DNA quantity and purity from all our study cases (mean concentration: 223.4 ± 104.16 ng/μL; mean A260/A280 ratio: 1.68 ± 0.09). Moreover, no statistically significant differences were observed between tumor blocks stored for 2-3 years and 7-8 years, respectively, both in terms of DNA quantity (p=0.196) and purity (p=0.663). In conclusion, we successfully validated an efficient, reproducible DNA extraction technique that provided a good range of DNA concentrations and purity, regardless the type of tissue (thyroid or kidney). Moreover, we demonstrated that the storage period of the FFPE blocks does not have a significant influence on the DNA quantity and purity.
authors.affiliation: Department of Histology, University of Medicine and Pharmacy of Tirgu Mures, Romania; andradaloghin@yahoo.com.
authors.forename: Adela Corina
authors.initials: AC
authors.lastname: Nechifor-Boilă
authors.forename: Andrada
authors.initials: A
authors.lastname: Loghin
authors.forename: Victor
authors.initials: V
authors.lastname: Vacariu
authors.forename: Vasile Bogdan
authors.initials: VB
authors.lastname: Halaţiu
authors.forename: Angela
authors.initials: A
authors.lastname: Borda
mesh_terms: D002277:Carcinoma / Q000235:genetics*; D004247:DNA / Q000737:chemistry; D005557:Formaldehyde / Q000737:chemistry*; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics*; D009369:Neoplasms / Q000378:metabolism*; D010232:Paraffin / Q000737:chemistry*; D016612:Paraffin Embedding; D013048:Specimen Handling; D013053:Spectrophotometry; D013964:Thyroid Neoplasms / Q000235:genetics*; D013997:Time Factors; D016707:Tissue Fixation / Q000379:methods
chemical_list: D005557:Formaldehyde; D010232:Paraffin; D004247:DNA