Proteomic analysis of differently archived breast cancer tissues

Currently, the most common practice of human breast tissue preservation is formalin fixation which ensures good quality for histopathological analyses but damages DNA, RNA, and proteins, impairing their usefulness for molecular analysis and biomarker investigations. We investigated the potential value of a non-toxic fixative for sparing proteins preserved in paraffin-embedded breast biopsies. Specimens were fixed in formalin-free fixative prior to paraffin embedding, and then processed for quality and quantity of protein conservation. Similar protein patterns were observed in formalin-free fixative and frozen tissues using mono- and bi-dimensional electrophoresis, as well as western blotting. Protein patterns assessed by mass spectrometric analysis were found to be identical for frozen and formalin-free-fixed tissues. Immunohistochemistry using various antibodies showed comparable results for both tissue storage methods. In conclusion, we believe that formalin-free fixative represents an easy-to-use alternative to formalin for archived tissue and for biomarker investigations, since it simultaneously protects both the histomorphology and the integrity of macromolecules.