DNA Topoisomerase II-alpha as a marker of cell proliferation in endocrine and other neoplasms.

DNA topoisomerases are enzymes that are able to link and unlink DNA strands. They are classified as type I or type II topoisomerase if they catalyze transient single-strand (topo I) or double-strand (topo II) DNA breaks. Topo II-alpha has been used as a proliferation marker and it can also serve as a molecular target for a variety of anticancer drugs that are used clinically.Topo II-alpha expression is similar to MIB1 immunoreactivity in breast, ovarian, cervix, gastric, endometrial, adrenocortical, and hematological malignancies. In a study of adrenocortical tumors with metastases topo II was significantly higher than in tumors without metastases.Studies of topo II-alpha expression may provide information about the biological behavior of specific tumors and may also provide insights into the role that this enzyme plays in the response of human cancers to topo II-targeted anticancer drugs.