Analysis of epothilone B-induced cell death in normal ovarian cells

Nuclear DNA Damage and Repair in Normal Ovarian Cells Caused by Epothilone B

This study was designed to assess, whether a new chemotherapeutic microtubule inhibitor, Epothilone B (EpoB, Patupilone), can induce DNA damage in normal ovarian cells (MM14.Ov), and to evaluate if such damage could be repaired. The changes were compared with the effect of paclitaxel (PTX) commonly employed in the clinic. The alkaline comet assay technique and TUNEL assay were used. The kinetics of DNA damage formation and the level of apoptotic cells were determined after treatment with IC50 concentrations of EpoB and PTX. It was observed that PTX generated significantly higher apoptotic and genotoxic changes than EpoB. The peak was observed after 48 h of treatment when the DNA damage had a maximal level. The DNA damage induced by both tested drugs was almost completely repaired. As EpoB in normal cells causes less damage to DNA it might be a promising anticancer drug with potential for the treatment of ovarian tumors.

New potential chemotherapy for ovarian cancer - Combined therapy with WP 631 and epothilone B

Despite more modern therapeutics approaches and the use of new drugs for chemotherapy, patients with ovarian cancer still have poor prognosis and therefore, new strategies for its cure are highly needed. One of the promising ways is combined therapy, which has many advantages as minimizing drug resistance, enhancing efficacy of treatment, and reducing toxicity. Combined therapy has rich and successful history in the field of ovarian cancer treatment. Currently use therapy is usually based on platinum-containing agent (carboplatin or cisplatin) and a member of taxanes (paclitaxel or docetaxel). In the mid-2000s this standard regimen has been expanded with bevacizumab, monoclonal antibody directed to Vascular Endothelial Growth Factor (VEGF). Another drug combination with promising perspectives is WP 631 given together with epothilone B (Epo B). WP 631 is a bisanthracycline composed of two molecules of daunorubicin linked with a p-xylenyl linker. Epo B is a 16-membered macrolide manifesting similar mechanism of action to taxanes. Their effectiveness against ovarian cancer as single agents is well established. However, the combination of WP 631 and Epo B appeared to act synergistically, meaning that it is much more potent than the single drugs. The mechanism lying under its efficacy includes disturbing essential cell cycle-regulating proteins leading to mitotic slippage and following apoptosis, as well as affecting EpCAM and HMGB1 expression. In this article, we summarized the current state of knowledge regarding combined therapy based on WP 631 and Epo B as a potential way of ovarian cancer treatment.

Epothilone B induces human ovarian cancer OV-90 cell apoptosis via external pathway

We evaluated molecular events associated with apoptosis induced by Epothilone B (EpoB, Patupilone) and paclitaxel (PTX) in human ovarian papillary serous adenocarcinoma cell line (OV-90). Epothilones are compounds of natural origin with mechanisms of action similar to taxanes, but with more potent antiproliferative activity. Apoptosis was one of the major forms of cell death induced by EpoB. The mode of cell death was assessed colorimetrically, fluorimetrically, cytometry, and by immunoblot analyses through measuring DNA fragmentation, the level of TRAIL, the cleavage of poly(ADP-ribose) polymerase (PARP) and the activation of caspase-9, -8 and -3. We measured also additional markers of apoptosis, like phosphatidylserine externalization and morphological changes. Moreover, we estimated glycoprotein P (P-gp) activity in OV-90 ovarian cancer cell line. The studies indicated that the extrinsic pathway of apoptosis, which is triggered by certain TNF family members and engages their respective receptors on the surface of the target cell, was predominant. We were the first to have demonstrated (using immunoassay) the release of TNF-related apoptosis-inducing ligand (TRAIL) after treatment with EpoB. EpoB and PTX mediate activation of both initiator caspases-8 and -9, leading to the appearance of caspase-3. In EpoB treated cells, DNA fragmentation was also detected. EpoB leads to the reduction in DNA repair capacity. In summary, we report that Epothilone B induces apoptosis in OV-90 cells via a TRAIL and caspase 8-dependent pathway. PTX leads to smaller apoptotic events in comparison to EpoB.