AI-guided design of plectin-1-targeted 68Ga-radiotracers reveals EP300-mediated membrane relocalization of plectin-1 in pancreatic ductal adenocarcinoma

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BACKGROUND: Plectin-1 (PLEC) is a membrane-associated biomarker implicated in the progression of pancreatic ductal adenocarcinoma (PDAC) and is an attractive target for molecular imaging. However, peptide-based radiotracers targeting PLEC remain limited, and the mechanisms linking plectin-1 relocalization to aggressive biology have yet to be fully elucidated. METHODS: Ga-labeled NOTA-conjugated plectin-1-targeted monomeric (FZPN) and dimeric (FZPN-dimer) radiotracers. Radiochemical characterization, surface plasmon resonance, cellular uptake, blocking, pharmacokinetic, microPET/CT, biodistribution, and preliminary toxicity studies were then undertaken in PANC-1 models. Mechanistic studies assessed the subcellular localization of PLEC, its interaction with EP300, acetylation, and the functional role of lysine 1310 (K1310). RESULTS: Ga]Ga-NOTA-FZPN-dimer exhibited high affinity for PLEC, favorable hydrophilicity and stability, and significantly higher cellular uptake and tumor accumulation than the monomeric tracer, with receptor-specific blockade in vitro and in vivo. In PANC-1 xenografts, tumor uptake of the dimer reached 3.8 ± 0.5%ID/g at 30 min after injection and remained higher than that of the monomer at all imaging time points. Mechanistically, PDAC tissues exhibited membrane-enriched PLEC; EP300 interacted with PLEC, acetylation was increased in PDAC cells, and the deacetylation-mimetic PLEC-K1310R mutant redirected plectin-1 away from the plasma membrane and reduced cell migration. CONCLUSIONS: Ga]Ga-NOTA-FZPN-dimer represents a promising PLEC-targeted PET radiotracer for molecular imaging in PDAC. EP300-mediated acetylation at K1310 appears to drive the membrane relocalization of PLEC and promote the migration of tumor cells, providing biological support for PLEC-targeted imaging and a rationale for further translational development.

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