Micellar curcumol reprograms tumor-associated macrophages and reverses PARP inhibitor resistance in recurrent ovarian cancer

Background Immunosuppressive tumor-associated macrophages (TAMs) in the malignant ascites contribute to Poly (ADP-ribose) polymerase inhibitor (PARPi) resistance in ovarian cancer (OC). Purpose This study aimed to investigate the activation efficacy of micelle loaded curcumol (MC) on TAMs and its impact on the resistance of OC cells to Niraparib. Methods Firstly, ID8-bearing mice with malignant ascites were treated with vehicle or MC, and single-cell RNA sequencing (scRNA-seq) was conducted to profile the immune cells’ transcriptome of the ascites. Then, macrophages derived from ascites of patients with recurrent high-grade serous OC undergoing PARPi therapy (ROCAMs), were comprehensively analyzed after MC treatment, including measurements of lactate and ATP, oxygen consumption rate (OCR) assay, and Complex Ⅰ and Ⅳ activity assays. Meanwhile, conditioned culture medium (CCM) from MC-treated ROCAMs was used to co-culture with Niraparib-resistant A2780 cells (A2780 NR ), followed by LC-MS/MS analysis. Finally, based on the LC‑MS/MS results, candidate cytokines that potentially reverse Niraparib resistance in OC cells were screened. The effects of these cytokines on A2780 NR cells were assessed by the CCK-8 assay. Results Intravenous injection of MC markedly reduced malignant ascites in ID8 tumor-bearing mice, as evidenced by decreased ascites volume, reduced abdominal circumference, and fewer tumor lesions. Analysis of the ascites cells by scRNA-seq showed that macrophages were a major immune cell population, with reduced immunosuppressive clusters ( Hmox1 and Gab2 ) in the MC-treated group. Further analysis using average gene expression scoring showed that MC treatment led to a significant reduction in M2 scores. In vitro treatment of patients’ ROCAMs with MC resulted in enhanced expression of TNF-α and suppressed expression of TGF-β, IL-6 and CD206, indicating that MC promotes transition of ROCAMs from an M2-like immunosuppressive state to an M1-like immunoactive state. Metabolic analysis of MC-treated ROCAMs and THP-1 showed that MC led to significant reductions in lactate production, ATP generation, OCR, and Complex IV activity, revealing that MC inhibits OXPHOS. NDUFA4, an essential structural protein of Complex IV, was found to be downregulated in both MC-treated ROCAMs and THP-1. Overexpression of NDUFA4 or restoration of NDUFA4 expression following MC treatment abrogated the inhibitory effect of MC on OXPHOS and partially reversed the MC-induced immune-active macrophage phenotype. Meanwhile, CCM from MC-treated ROCAMs enhanced the sensitivity of A2780 NR cells to Niraparib, with the IC 50 decreasing from 110.94 ± 22.52 μM to 65.98 ± 21.59 μM. IL-1β and IL-18 were identified as potential candidates by LC-MS/MS, and co-treatment with IL-1β and IL-18 sensitized A2780 NR cells to Niraparib (IC 50 was 39.25 ± 1.44 μM). Conclusion Our study reveals that MC could promote macrophage activation by inhibiting NDUFA4 and increase the sensitivity of OC cells to Niraparib.