Newly developed dual topoisomerase inhibitor P8-D6 is highly active in ovarian cancer

Abstract

Background: Ovarian cancer (OvCa) constitutes a rare and highly aggressive malignancy and is one of the most lethal of all gynaecologic neoplasms. Due to chemotherapy resistance and treatment limitations because of side effects, OvCa is still not sufficiently treatable. Hence, new drugs for OvCa therapy such as P8-D6 with promising antitumour properties have a high clinical need. The benzo[ c]phenanthridine P8-D6 is an effective inductor of apoptosis by acting as a dual topoisomerase I/II inhibitor. Methods: In the present study, the effectiveness of P8-D6 on OvCa was investigated in vitro. In various OvCa cell lines and ex vivo primary cells, the apoptosis induction compared with standard therapeutic agents was determined in two-dimensional monolayers. Expanded by three-dimensional and co-culture, the P8-D6 treated cells were examined for changes in cytotoxicity, apoptosis rate and membrane integrity via scanning electron microscopy (SEM). Likewise, the effects of P8-D6 on non-cancer human ovarian surface epithelial cells and primary human hepatocytes were determined. Results: This study shows a significant P8-D6-induced increase in apoptosis and cytotoxicity in OvCa cells which surpasses the efficacy of well-established drugs like cisplatin or the topoisomerase inhibitors etoposide and topotecan. Non-cancer cells were affected only slightly by P8-D6. Moreover, no hepatotoxic effect in in vitro studies was detected. Conclusion: P8-D6 is a strong and rapid inductor of apoptosis and might be a novel treatment option for OvCa therapy.

High Antitumor Activity of the Dual Topoisomerase Inhibitor P8-D6 in Breast Cancer

“…A major requirement for drug effectiveness is that the drug reaches its nuclear target structure-DNA-topo I and II complex. In addition to previous studies on colon cancer and ovarian cancer cells [ 5 , 19 ], this study confirms the localization of P8-D6 in the cytoplasm and the nucleus of BC cells after treatment ( Figure 2 A–C). It was determined that P8-D6 reached the cell nucleus by quantifying the fluorescence intensity per nuclear area ( Figure 2 C, Supplementary Figure S1B,C ) In addition, the colocalization of P8-D6 and topo I was detected by fluorescence staining ( Figure 2 (Aii), Supplementary Figure S1A ).…”

“…To investigate the toxicity of P8-D6, we determined the hepatotoxicity of P8-D6 on human hepatocytes in previous studies and tested P8-D6 on non-tumor-associated ovarian epithelia cells. In that analysis, the cell integrity in non-cancer cells was slightly affected, and no hepatotoxic effect was detected in in vitro studies [ 19 ]. In characterizing the mechanism of action of P8-D6, it was previously shown that it acts as a dual topo inhibitor [ 5 ].…”

“…Samples were analyzed by determining apoptosis based on Caspase 3/7 activity. The validation of these methods was conducted using a second method based on flow cytometry and Annexin V/7AAD staining as a complementary method in our previous study [ 19 ]. As these two methods delivered similar results, the caspase 3/7 assays were used for further studies.…”

Combined PARP and Dual Topoisomerase Inhibition Potentiates Genome Instability and Cell Death in Ovarian Cancer

“…A new promising compound for OC therapy is the dual topoisomerase inhibitor P8-D6. P8-D6 was investigated as a single-drug in in vitro studies in a translational approach and showed high antitumoral efficacy [8,9]. P8-D6 is an inductor of apoptosis by acting as a dual topoisomerase poison.…”

“…P8-D6 is an aza-analogous Benzo[c]phenanthridine with cytotoxic properties [17]. Its high efficacy in the therapy of OC and breast cancer was recently demonstrated in 2D monolayer cell culture and spheroids [8,9].…”