ki-67 and Topoisomerase IIa proliferation markers in colon adenocarcinoma.

Aberrant cell proliferation is a major cause in the development and progression of carcinogenic process. Epithelia characterized by increased mitotic rates accumulate easily gross numerical and structural chromosomes (polysomy/aneuploidy) and specific gene (deletions, amplifications, point mutations, translocations) deregulations that lead to their progressive neoplastic and finally malignant transformation. Molecules that are critical for evaluating the proliferation status of the corresponding tissues include mainly ki-67 (cytogenetic band: 10q26.2), and also Topoisomerase IIa/Topo IIa (cytogenetic band: 17q21.2). Both of them demonstrate different expression patterns in every cell cycle phase and their estimated expression as Nuclear Labeling Index (NLI) is a very useful tool for assessing the aggressiveness of the examined pre- and malignant tissues. In fact, ki-67 expression increases as a cell progresses through the cell cycle, with highest expression being seen in G2/M phase cell, whereas Topo IIa is expressed in proliferating cells in the late S phase with a peak in G2-M phases. Concerning colon adenocarcinoma, high expression levels of them seem to correlate with advanced disease and also with modified response rates to specific chemotherapeutic agents, such as doxorubicin, an inhibitor of Topo IIa. In the current molecular review we explored the role of these proliferative markers in colon adenocarcinoma and their influence in the tumor biological behavior.