Enzymatic Assemblies of Thiophosphopeptides Instantly Target Golgi Apparatus and Selectively Kill Cancer Cells**

Aptamer-Array-Guided Protein Assembly Enhances Synthetic mRNA Switch Performance

Synthetic messenger RNA (mRNA) switches are powerful synthetic biological tools that can sense cellular molecules to manipulate cell fate. However, their performances are limited by high output signal noise due to leaky output protein expression. Here, we designed a readout control module that disables protein leakage from generating signal. Aptamer array on the switch guides the inactive output protein to self-assemble into functional assemblies that generate output signal. Leaky protein expression fails to saturate the array, thus produces marginal signal. In this study, we demonstrated that switches with this module exhibit substantially lower signal noise and, consequently, higher input sensitivity and wider output range. Such switches are applicable for different types of input molecules and output proteins. The work here demonstrates a new type of spatially guided protein self-assembly, affording novel synthetic mRNA switches that promise accurate cell manipulation for biomedical applications.

In Situ Self-Assembly of Bispecific Peptide for Cancer Immunotherapy

Precise and effective manipulation of protein functions still faces tremendous challenges. Herein we report a programmable peptide molecule, consisted of targeting and self-assembly modules, that enables specific and highly efficient assembly governed by targeting receptor proteins. Upon binding to the cell membrane receptor, peptide conformation is somewhat stabilized along with decreased self-assembly activation energy, promoting peptide-protein complex oligomerization. We first design a GNNQQNY-RGD peptide (G7-RGD) to recognize integrin α_V β₃ receptor for proof-of-concept study. In the presence of α_V β₃ protein, the critical assembly concentration of free G7-RGD decreases from 525 to 33 μM and the resultant G7-RGD cluster drives integrin receptor oligomerization. Finally, a bispecific assembling peptide antiCD3-G7-RGD is rationally designed for cancer immunotherapy, which validates CD3 oligomerization and concomitant T cell activation, leading to T cell-mediated cancer cell cytolysis.

Assembly Transformation Jointly Driven by the LAP Enzyme and GSH Boosting Theranostic Capability for Effective Tumor Therapy

Developing intelligent and morphology-transformable nanomaterials that can spatiotemporally undergo stimulus-responsive size transformation holds great promise for improving the tumor delivery efficiency of drugs in vivo. Here, we report a smart size-transformable theranostic probe Ce6-Leu consisting of a leucine amino peptidase (LAP) and glutathione (GSH) dual-responsive moiety, an 1,2-aminothiol group, and a clinically used photosensitizer Ce6. This probe tends to self-assemble into uniform nanoparticles with an initial size of ∼80 nm in aqueous solution owing to the amphiphilic feature. Surprisingly, taking advantage of the biocompatible CBT-Cys condensation reaction, the large nanoprobes can be transformed into tiny nanoparticles (∼23 nm) under the joint action of LAP and GSH in a tumor microenvironment, endowing them with great tumor accumulation and deep tissue penetration. Concomitantly, this LAP/GSH-driven disassembly and size shrinkage of Ce6-Leu can also activate the fluorescence/magnetic resonance signals and the photodynamic effect for enhanced multimodal imaging-guided photodynamic therapy of human liver HepG2 tumors in vivo. More excitingly, the Mn²⁺-chelating probe (Ce6-Leu@Mn²⁺) was demonstrated to have the capability to catalyze endogenous H₂O₂ to persistently release O₂ at the hypoxic tumor site, as a consequence improving the oxygen supply to boost the radiotherapy effect. We thus believe that this LAP/GSH-driven size-transformable nanosystem would offer a novel advanced technology to improve the drug delivery efficiency for achieving precise tumor diagnosis and treatment.

In Vivo Self-Assembly Induced Cell Membrane Phase Separation for Improved Peptide Drug Internalization

Therapeutic peptides have been widely concerned, but their efficacy is limited by the inability to penetrate cell membranes, which is a key bottleneck in peptide drugs delivery. Herein, an in vivo self-assembly strategy is developed to induce phase separation of cell membrane that improves the peptide drugs internalization. A phosphopeptide KYp is synthesized, containing an anticancer peptide [KLAKLAK]₂ (K) and a responsive moiety phosphorylated Y (Yp). After interacting with alkaline phosphatase (ALP), KYp can be dephosphorylated and self-assembles in situ, which induces the aggregation of ALP and the protein-lipid phase separation on cell membrane. Consequently, KYp internalization is 2-fold enhanced compared to non-responsive peptide, and IC₅₀ value of KYp is approximately 5 times lower than that of free peptide. Therefore, the in vivo self-assembly induced phase separation on cell membrane promises a new strategy to improve the drug delivery efficacy in cancer therapy.