IMMUNOHISTOCHEMICAL STAINING FOR DNA TOPOISOMERASE-II IN FROZEN AND FORMALIN-FIXED PARAFFIN-EMBEDDED HUMAN TISSUES

DNA topoisomerase II is the molecular target of several clinically use ful chemotherapeutic drugs. The sensitivity of cells to drugs that tar get topoisomerase II is dependent on the cellular content of this enzy me. Drug-sensitive cells have elevated amounts of type IT topoisomeras e. To determine relative amounts of enzyme in malignant neoplasms, we developed an in situ immunohistochemical stain for topoisomerase II. T he stain uses either polyclonal or monoclonal antibodies produced agai nst the a isoform of the enzyme. Staining can be done on both frozen a nd formalin-fixed, paraffin-embedded tissues. By using this immunostai n, we found marked differences in enzyme content in several human mali gnancies.