RESEARCH ARTICLE Evaluation of characteristi r

Full list of author information is available at the end of the articleBackground Ovarian cancer is the number one leading cause of death among gynecologic malignancies. This is due mainly to the prevalence of this undetected metastatic disease as over 90 % of malignant tumors are epithelial ovarian can-cer (EOC). Although the standard therapy of optimal cytoreductive surgery followed by the systemic chemo-therapy with platinum-paclitaxel (PTX) has resulted in a complete remission in over 70 % patients with EOC, the overall 5-year survival rate has been less than 30%. Most patients will relapse within 2 years after the treatment as development of resistance to platinum-PTX-based chemo-therapy has developed. Moreover, recurred tumors tend to became unresponsive to additional chemotherapy [1-3]. Cancer stem cells (CSCs) represent a distinct subpopu-lation of the tumor cells that play an important role in the tumor initiation, progression, metastasis, chemoresistance and relapse [4,5]. Recent advance in in vitro experiment has shown more resistance to treatment with cisplatin (CDDP) and PTX by EOC CSCs than by their differen-tiated progeny [6]. It is believed that the cytotoxic effects of chemotherapy kill most cells in a tumor but CSCs are leave behind; this might be an important mechanism o