Liquid-liquid phase separation (LLPS) plays important roles in various cellular processes, facilitating membrane-less organelles construction, chromatin condensation, signal transduction on inner membrane and many other processes. Current perception is that LLPS relies on weak multivalent interactions and crowded environments intracellularly. In this study, we demonstrate that heparan sulfate can serve as a platform to induce the phase separation of basic fibroblast growth factor on cell surface. The phase separation model provides an alternative mechanism how bFGF is enriched to its receptors, therefore triggering the signaling transduction. The research provides insights on the mechanism how growth factors can be recruited to cell surface by heparan sulfate and execute their functions, extending people’s view on phase separation from intracellular to extracellular proteins at cellular level.

Anticancer peptides are promising drug candidates for cancer treatment, but the short circulation time and low delivery efficiency limit their clinical applications. Herein, we designed several lasso-like self-assembling anticancer peptides (LASAPs) integrated with multiple functions by a computer-aided approach. Among these LASAPs, LASAP1 (CRG­DKG­PDC­GKA­FRR­FLG­ALF­KAL­SHLL, 1–9 disulfide bond) was determined to be superior to the others because it can self-assemble into homogeneous nanoparticles and exhibits improved stability in serum. Thus, LASAP1 was chosen for proving the design idea. LASAP1 can self-assemble into nanoparticles displaying iRGD on the surface because of its amphiphilic structure and accumulate to the tumor site after injection because of the EPR effect and iRGD targeting to αVβ3 integrin. The nanoparticles could disassemble in the acidic microenvironment of the solid tumor, and cleaved by the overexpressed hK2, which was secreted by prostate tumor cells, to release the effector peptide PTP-7b (FLG­ALF­KAL­SHLL), which was further activated by the acidic pH. Therefore, LASAP1 could target the orthotopic prostate tumor in the model mice after intraperitoneal injection and specifically inhibit tumor growth, with low systematic toxicity. Combining the multiple targeting functions, LASAP1 represents a promising design of self-delivery of peptide drugs for targeted cancer treatments.

Chronic pain is one of the most prevalent health problems worldwide. An alternative to suppress or alleviate chronic pain is the use of peptide drugs that block N-type Ca2+ channels (Cav2.2), such as ω-conotoxin MVIIA. Nevertheless, the narrow therapeutic window, severe neurological side effects and low stability associated with peptide MVIIA have restricted its widespread use. Fortunately, self-assembly endows the peptide with high stability and multiple functions, which can effectively control its release to prolong its duration of action. Inspired by this, MVIIA was modified with appropriate fatty acid chains to render it amphiphilic and easier to self-assemble. In this paper, an N-terminal myristoylated MVIIA (Myr-MVIIA, medium carbon chain length) was designed and prepared to undergo self-assembly. The present results indicated that Myr-MVIIA can self-assemble into micelles. Self-assembled micelles formed by Myr-MVIIA at higher concentrations than MVIIA can prolong the duration of the analgesic effect and significantly reduce or even eliminate the side effects of tremor and coordinated motor dysfunction in mice.

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Antibody‐directed drugs for targeted cancer treatment have become a hot topic in new anticancer drug development; however, antibody‐fused therapeutic peptides were rarely documented. Herein, we designed a fusion protein with a cetuximab‐derived single‐chain variable fragment targeting epidermal growth factor receptor (anti‐EGFR scFv) and the anticancer lytic peptide (ACLP) ZXR2, connected by a linker (G4S)3 and MMP2 cleavage site. The anti‐EGFR scFv‐ZXR2 recombinant protein showed specific anticancer activity on EGFR‐overexpressed cancer cell lines in a concentration‐ and time‐dependent manner, as it can bind to EGFR on cancer cell surfaces. This fusion protein caused cell membrane lysis as ZXR2, and showed improved stability in serum compared with ZXR2. These results suggest that scFv‐ACLP fusion proteins may be potential anticancer drug candidates for targeted cancer treatment, which also provide a feasible idea for targeted drug design.