Curcumin Alleviates Endometriosis in Sexually Mature Female Mice by Targeting PKA and Inhibiting De Novo Estrogen Synthesis

Background: Endometriosis is an estrogen-dependent disorder with limited treatment options. The precise molecular targets of curcumin and its effects on local estrogen synthesis in this disease remain unclear. Methods: We investigated curcumin’s efficacy and mechanism via network pharmacology, in vitro functional assays in ectopic endometrial cells, an allogeneic mouse model, and target validation through molecular docking, thermal shift, and hydrolysis stability assays. Results: Curcumin significantly inhibited ectopic cell malignant phenotypes, reducing migration distance by 55.60 ± 7.32%, 80.34 ± 11.19%, and 82.88 ± 13.67% at 5, 10, and 15 μM, respectively, and decreasing invasive cell numbers by 40.38 ± 7.67%, 58.33 ± 12.70%, and 60.18 ± 9.07%, respectively (all p < 0.05). In a mouse model, curcumin (200 mg/kg/day) reduced lesion number by 38.46% (2.167 ± 0.752 vs. 1.333 ± 0.516, p = 0.0493) and lesion volume by 59.73% (0.0497 ± 0.0173 vs. 0.0200 ± 0.0130 mm3, p = 0.00732). It also suppressed de novo estrogen synthesis and modulated the estrogen receptor α (ERα) and β (ERβ) ratio. Mechanistically, curcumin directly bound to and inhibited protein kinase A (PKA), a key kinase in the cAMP signaling pathway. Conclusions: We first demonstrate that curcumin alleviates endometriosis by targeting PKA to inhibit local estrogen synthesis, identifying PKA as a novel therapeutic target and curcumin as a promising treatment candidate.