Plasma-activated liquid mediated sensitization of cisplatin in chemoresistant ovarian cancer by disrupting DNA damage response

Cisplatin resistance coupled with adverse effects presents substantial hurdles in the treatment of ovarian cancer. Both cold atmospheric plasma and plasma-activated liquid (PAL) hold the ability to induce DNA damage, which is a primary target of cisplatin. In this study, we investigate the potential of PAL in augmenting cisplatin sensitivity or diminishing the necessary drug dosage by impairing the DNA of cisplatin-resistant cancer cells. We found that plasma irradiated medium exceeding 40 s could decrease the viability, induce DNA damage, trigger cell cycle arrest, and augment apoptosis and autophagy in two types of cisplatin-resistant ovarian cancer cells (A2780/DDP and SKOV3/DDP) after a 24 h incubation period. Notably, pre-treatment with 40 s plasma-activated medium (PAM) for 2 h significantly enhanced the anti-cancer effect of cisplatin administered at lower doses on these cell types. RNA-seq, quantitative real-time PCR and Western blotting analysis revealed that PAM treatment could downregulate the expression of several pivotal proteins involved in nucleotide excision repair (NER) and homologous recombination repair (HRR). The mouse xenograft tumor model demonstrated that plasma-activated saline and cisplatin synergistically inhibited tumor growth and significantly suppressed the expression of proteins related to HRR and NER pathways. We identified plasma-derived peroxide generation in PAM as crucial in these processes. These results pave the way for considering PAM as an adjuvant treatment for cisplatin-resistant ovarian cancer and other abdominal cancers. Additionally, the findings indicate the feasibility of reducing cisplatin dosage to alleviate side effects through sensitization.