TOP2A overexpression in hepatocellular carcinoma correlates with early age onset, shorter patients survival and chemoresistance.

Genomic gain represents an important mechanism in the activation of proto-oncogenes. In many instances, induced oncogenes hold clinical implications both as prognostic markers and targets for therapeutic design. In hepatocellular carcinoma (HCC), although chromosomal gains are common, information on underlying oncogenes induced remains minimal. Here, we examined 7 causal sites of HCC for overexpressed genes by array-based transcriptional mapping. In 22 HCC cell lines and early passages of cultures studied, clusters of up-regulated genes were indicated, where TOP2A expression ranked the highest. Distinct TOP2A transcriptions were confirmed in an independent series of HCC tumors relative to adjacent non-tumoral liver (p=0.0018). By tissue microarray analysis of 172 HCC, we found TOP2A expressions correlated with advance histological grading (p<0.001), microvascular invasion (p=0.004) and an early age onset of the malignancy (<or=40 years; p=0.007). In conjunction with P-gp and MRP1, TOP2A were further assessed for its association with chemotherapy responsiveness and survival in 148 patients who entered our recently reported Phase III prospective randomized study. In 73 chemoresistant and 75 nonresistant patients, only TOP2A positivity correlated with chemoresistance (p=0.029) and shorter patients survival (p<0.0001). The potential therapeutic value in targeting TOP2A by Etoposide, as a single agent, and in combination with Doxorubicin was also explored. In vitro cytotoxic studies suggested Etoposide at IC20 readily reduced IC50 values of Doxorubicin by a magnitude of approximately 3.5 to 10-fold compared to Doxorubicin alone (p<0.028). Our study highlighted for the first time the prognostic value of TOP2A in HCC and the potential use of TOP2A reactive agents in therapy.