Dual-site spatiotemporal and simultaneous inhibition on PIN1 via arsenic-retinoic albumin nanoparticles enables synergistic oncotherapy

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) is a master regulator of oncogenic signaling, uniquely catalyzing the isomerization of phosphorylated Ser/Thr-Pro motifs to drive malignant transformation, proliferation, and metastasis. Despite its central role in tumorigenesis, effective therapeutic targeting of Pin1 remains unmet. Current inhibitors such as all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) show limited efficacy due to their insufficient potency as standalone agents. Here, we report the rational design of dual-drug-conjugated human serum albumin nanoparticles (ATRA-ATO-NPs) that enable dual-site, spatiotemporal, and simultaneous inhibition of Pin1. These engineered nanoparticles exhibit uniform morphology, sustained co-release kinetics, and enhanced tumor accumulation via improved permeability and retention. In vitro, ATRA-ATO-NPs achieved synergistic inhibition of hepatocellular carcinoma proliferation and migration, significantly outperforming free or co-administered drugs. In vivo, ATRA-ATO-NPs produced superior tumor suppression and reduced lung metastasis in murine models without inducing hematologic or organ toxicity. Mechanistically, proteomic and pathway enrichment analyses revealed broader and deeper inhibition of Pin1-regulated oncogenic and metabolic networks─including Wnt/β-catenin, NF-κB, and CDK signaling─compared to either drug alone. Collectively, ATRA-ATO-NPs offer a mechanistically targeted, systemically safe, and highly effective strategy for advanced oncotherapy through dual-site spatiotemporal and simultaneous Pin1 inhibition.