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

A comparative study of novel ruthenium(III) and iron(III) complexes containing uracil; docking and biological studies

Structural and biological studies were conducted on the novel complexes [Fe(U)2(H2O)2]Cl3 (FeU) and [Ru(U)2(H2O)2]Cl3 (RuU) (U = 5,6-Diamino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione) to develop an anticancer drug candidate. The two complexes have been synthesized and characterized. Based on our findings, these complexes have octahedral geometry. The DNA-binding study proved that both complexes coordinated with CT-DNA. The docking study confirmed the potency of both complexes in downregulating the topoisomerase I protein through their high binding affinity. Biological studies have established that both complexes can act as potent anticancer agents against three cancer cell lines. RuU or FeU complexes induce apoptosis in breast cancer cells by increasing caspase9 protein and inhibiting proliferating cell nuclear antigen (PCNA) activity. In addition, both complexes down-regulate topoisomerase I expression in breast cancer cells. Therefore, the RuU and FeU complexes' anticancer activities were mediated via both apoptosis induction and topoisomerase I down-regulation. In conclusion, both complexes have dual anticancer activity pathways that may be responsible for the selective cytotoxicity of the complexes. This makes them more suitable for the development of novel cancer treatment strategies.

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

Although ovarian cancer is a rare disease, it constitutes the fifth leading cause of cancer death among women. It is of major importance to develop new therapeutic strategies to improve survival. Combining P8-D6, a novel dual topoisomerase inhibitor with exceptional anti-tumoral properties in ovarian cancer and compounds in preclinical research, and olaparib, a PARP inhibitor targeting DNA damage repair, is a promising approach. P8-D6 induces DNA damage that can be repaired by base excision repair or homologous recombination in which PARP plays a major role. This study analyzed benefits of combining P8-D6 and olaparib treatment in 2D and 3D cultures with ovarian cancer cells. Measurement of viability, cytotoxicity and caspase activity were used to assess therapy efficacy and to calculate the combination index (CI). Further DNA damage was quantified using the biomarkers RAD51 and γH2A.X. The combinational treatment led to an increased caspase activity and reduced viability. CI values partially show synergisms in combinations at 100 nM and 500 nM P8-D6. More DNA damage accumulated, and spheroids lost their membrane integrity due to the combinational treatment. While maintaining the same therapy efficacy as single-drug therapy, doses of P8-D6 and olaparib can be reduced in combinational treatments. Synergisms can be seen in some tested combinations. In summary, the combination therapy indicates benefits and acts synergistic at 100 nM and 500 nM P8-D6.

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

Breast cancer constitutes the leading cause of cancer deaths among females. However, numerous shortcomings, including low bioavailability, resistance and significant side effects, are responsible for insufficient treatment. The ultimate goal, therefore, is to improve the success rates and, thus, the range available treatment options for breast cancer. Consequently, the identification, development and evaluation of potential novel drugs such as P8-D6 with seminal antitumor capacities have a high clinical need. P8-D6 effectively induces apoptosis by acting as a dual topoisomerase I/II inhibitor. This study provides an overview of the effectiveness of P8-D6 in breast cancer with both 2D monolayers and 3D spheroids compared to standard therapeutic agents. For this drug effectiveness review, cell lines and ex vivo primary cells were used and cytotoxicity, apoptosis rates and membrane integrity were examined. This study provides evidence for a significant P8-D6-induced increase in apoptosis and cytotoxicity in breast cancer cells compared to the efficacy of standard therapeutic drugs. To sum up, P8-D6 is a fast and powerful inductor of apoptosis and might become a new and suitable therapeutic option for breast cancer in the future.