Resistance Improvement and Sensitivity Enhancement of Cancer Therapy by a Novel Antitumor Candidate onto A2780 CP and A2780 S Cell Lines.

Background: To overcome cisplatin resistance, the cytotoxicity of a novel antitumor agent on two ovarian cancer cell lines sensitive and resistant to cisplatin was investigated.

Methods: MTT assay and flow cytometry were performed to assess the cytotoxicity of a novel water-soluble Pd (II) complex, [Pd(bpy)(pyr-dtc)]NO₃ (PBPD), on cisplatin-sensitive and cisplatin-resistant ovarian cancer cell lines. Furthermore, variations in the expression of drug resistance gene cluster of differentiation 99 (CD99), signal transducer and activator of transcription 3 (STAT3), octamer-binding transcription factor 4 (OCT4), and multidrug resistance mutation 1 (MDR1) were evaluated using Real-Time PCR.

Results: The IC50 values of PBPD in resistant cells were higher than those in sensitive cells. Furthermore, PBPD has a deadlier effect on sensitive cells compared to resistant cells, and the cell survival rate is reduced over time. Flow cytometry revealed that PBPD enhanced the population of living-resistant cells while driving them to apoptosis. PBPD, on the other hand, has a greater effect on the living cell population and has dramatically shifted the population toward apoptosis and necrosis in the sensitive cells. Furthermore, gene expression analysis showed that when sensitive and resistant cells were treated with cisplatin, all resistance genes increased significantly relative to the control. In contrast to OCT4, MDR1, STAT3, and CD99 resistance genes were not significantly elevated in sensitive cells treated with PBPD compared to the control. Thus, the expression of resistance genes in resistant cells treated with PBPD was lower than cisplatin.

Conclusions: As a result, PBPD is a promising anticancer agent for CDDP-resistant ovarian cancer.