Targeting ALKBH5 with cisplatin-Ga nanodrug to investigate platinum sensitivity in resistant ovarian cancer through m6A-dependent mechanisms.

e17595 Background: Platinum-based combination chemotherapy remains a cornerstone in the treatment of ovarian cancer. However, the development of platinum resistance in most patients poses a significant clinical challenge. N6-methyladenine (m6A) modifications, a critical form of epigenetic regulation, influence RNA stability, splicing, and translation, thereby modulating tumor behavior. Emerging evidence highlights the pivotal role of m6A in mediating platinum resistance. Gallium (Ga), which shares charge and ionic radius similarities with iron (Fe), can disrupt iron homeostasis by forming complexes with iron-binding proteins and ligands, such as transferrin, and impair the activity of iron-dependent enzymes. ALKBH5, an m6A demethylase, relies on two iron ions at its active site for catalytic activity. Consequently, targeting iron homeostasis with Ga to modulate ALKBH5 function may offer a novel approach to reversing platinum resistance in ovarian cancer. Methods: To enhance the efficacy of cisplatin in platinum-resistant ovarian cancer, we developed a nanodrug, Cisplatin-Ga. The effects of cisplatin, Ga, and Cisplatin-Ga were evaluated using CCK-8 assays, colony formation assays, and flow cytometry. Immunofluorescence was employed to assess DNA damage, while Western blotting was used to measure changes in protein expression following nanodrug treatment. RNA sequencing (RNA-seq) analysis was performed on A2780-cisR cells treated with cisplatin, Ga, or Cisplatin-Ga for 48 hours to elucidate downstream mechanisms. Results: 1. Compared to cisplatin alone, Cisplatin-Ga significantly suppressed cell viability, induced DNA damage, and enhanced apoptosis in cisplatin-resistant ovarian cancer cell lines (A2780-cisR and SKOV3-cisR) in vitro. 2. Ga treatment downregulated the protein levels of the m6A demethylase ALKBH5. 3.ALKBH5 downregulation increased m6A modification levels on the DDIT4 transcript, leading to DDIT4 RNA degradation, elevated DNA damage, and enhanced cisplatin efficacy. Conclusions: The Cisplatin-Ga nanodrug downregulates ALKBH5 protein levels, promotes DDIT4 RNA degradation, and reduces DDIT4 protein expression, resulting in increased DNA damage and enhanced cisplatin efficacy in platinum-resistant ovarian cancer. These findings demonstrate a promising strategy for overcoming platinum resistance using Cisplatin-Ga, highlighting its potential as a therapeutic intervention for resistant ovarian cancer.