Using the Power of Junctional Adhesion Molecules Combined with the Target of CAR-T to Inhibit Cancer Proliferation, Metastasis and Eradicate Tumors

Aiming the magic bullet: targeted delivery of imaging and therapeutic agents to solid tumors by pHLIP peptides

The family of pH (Low) Insertion Peptides (pHLIP) comprises a tumor-agnostic technology that uses the low pH (or high acidity) at the surfaces of cells within the tumor microenvironment (TME) as a targeted biomarker. pHLIPs can be used for extracellular and intracellular delivery of a variety of imaging and therapeutic payloads. Unlike therapeutic delivery targeted to specific receptors on the surfaces of particular cells, pHLIP targets cancer, stromal and some immune cells all at once. Since the TME exhibits complex cellular crosstalk interactions, simultaneous targeting and delivery to different cell types leads to a significant synergistic effect for many agents. pHLIPs can also be positioned on the surfaces of various nanoparticles (NPs) for the targeted intracellular delivery of encapsulated payloads. The pHLIP technology is currently advancing in pre-clinical and clinical applications for tumor imaging and treatment.

Cancer cells targeting with genetically engineered constructs based on a pH-dependent membrane insertion peptide and fluorescent protein

The targeted delivery of nanodrugs to malignant neoplasm is one of the most pressing challenges in the development of modern medicine. It was reported earlier that a bacteriorhodopsin-derived pH low insertion peptide (pHLIP) targets acidic tumors and has the ability to translocate low molecular weight cargoes across the cancer cell membrane. Here, to better understand the potential of pHLIP-related technologies, we used genetically engineered fluorescent protein (EGFP) as a model protein cargo and examined targeting efficiencies of EGFP-pHLIP hybrid constructs in vitro with the HeLa cell line at different pHs. By two independent monitoring methods we observed an increased binding affinity of EGFP-pHLIP fusions to HeLa cells at pH below 6.8. Confocal images of EGFP-pHLIP-treated cells showed bright fluorescence associated with the cell membrane and fluorescent dots localized inside the cell, that became brighter with time. To elucidate the pHLIP-mediated EGFP cell entry mechanisms, we performed a series of experiments with specific inhibitors of endocytosis. Our results imply that EGFP-pHLIP internalization is realized by endocytosis of various types.