Calcium-Mediated Cell Adhesion Enhancement-Based Antimetastasis and Synergistic Antitumor Therapy by Conjugated Polymer-Calcium Composite Nanoparticles.

Strengthening tumor cellular adhesion through regulating the concentration of extracellular Ca is highly challenging and promising for antimetastasis. Herein, a pH-responsive conjugated polymer-calcium composite nanoparticle (PFV/CaCO/PDA@PEG) is developed for calcium-mediated cell adhesion enhancement-based antimetastasis and reactive oxygen species (ROS)-triggered calcium overload and photodynamic therapy (PDT) synergistic tumor treatment. PFV/CaCO/PDA@PEG is mainly equipped with conjugated poly(fluorene--vinylene) (PFV-COOH)-composited CaCO nanoparticles, which can be rapidly decomposed under the tumor acidic microenvironment, effectively releasing Ca and the photosensitizer PFV-COOH. The high extracellular Ca concentration facilitates the generation of dimers between two adjacent cadherin ectodomains, which greatly enhances cell-cell adhesion and suppresses tumor metastasis. The inhibition rates are 97 and 87% for highly metastatic tumor cells 4T1 and MCF-7, respectively. Such a well-designed nanoparticle also contributes to realizing PDT, mitochondrial dysfunction, and ROS-triggered Ca overload synergistic therapy. Furthermore, PFV/CaCO/PDA@PEG displayed superior inhibition of 4T1 tumor growth and demonstrated a marked antimetastatic effect by both intravenous and intratumoral injection modes. Thus, this study provides a powerful strategy for calcium-mediated metastasis inhibition for tumor therapy.