LAH4

The mortality of ovarian cancer stably ranks first in gynecological malignancies due to the lack of specific symptoms and diagnostic methods at an early stage. For most patients, the cancer cells had metastasized before they were diagnosed. As a result, 90% of them died of multidrug resistance (MDR) to chemotherapeutics. In our study, RNAi technology was introduced and applied to overcome this big problem. LAH4-L1, an amphipathic cationic polypeptide, was reported to have high transfection efficiency and was first selected by us to deliver siMDR1 for overcoming ovarian cancer cells MDR. In this research, LAH4-L1-siRNA nanocomplexes (LSCs) delivery system was designed via electrostatic interactions. The nanocomplexes could realize 87.3% MDR1 gene silence and 85% P-gp down-regulation on SKOV-3 cells. What's more, with the combination of chemotherapeutics, SKOV-3 cells growth inhibition can reach to 82.9%. We have also found that there was about 50% reduction on cells migration when MDR1 gene was down-regulated. Besides what have been mentioned above, physicochemical characteristics, cytotoxicity, pH responsivity, cells cycle, cellular uptake, and endosomal escape abilities were also studied in this research. In conclusion, lower cytotoxicity, higher down-regulation of targeted gene, and great cell inhibition, when combined with chemotherapeutics, all show the great potential of LSCs for the reversal of multidrug resistance on SKOV-3 cells in the future.

Lentiviral vectors (LVs) are promising delivery systems for gene therapy. To enhance the efficiency of target cell transduction by LVs, protocols often include the addition of culture additives. In this study, the cationic amphipathic peptide LAH4-L1 (KKALLAHALHLLALLALHLAHALKKA), a DNA transfection agent, was evaluated for its capacity to improve LV infectivity in cell lines and primary cells. Results show that LAH4-L1 enhances infectivity of all LV pseudotypes tested, particularly GALVTR-LVs. More importantly, LAH4-L1 promotes the transduction of CD34+ hematopoietic stem cells with GALVTR-LVs as efficiently as Retronectin, a culture additive used in ex vivo clinical protocols involving LVs. The action of LAH4-L1 relies both on the GALVTR-LV adhesion and post-adhesion steps. LAH4-L1 represents a new and attractive transduction enhancer for hematopoietic gene therapy protocols.

The histidine-rich designer peptides of the LAH4 family exhibit potent antimicrobial, transfection, transduction and cell-penetrating properties. They form non-covalent complexes with their cargo, which often carry a negative overall charge at pH 7.4 and include a large range of molecules and structures such as oligonucleotides, including siRNA and DNA, peptides, proteins, nanodots and adeno-associated viruses. These complexes are thought to enter the cells through an endosomal pathway where the acidification of the organelle is essential for efficient endosomal escape. Biophysical measurements indicate that, upon acidification, almost half the peptides are released from DNA cargo, leading to the suggestion of a self-promoted uptake mechanism where the liberated peptides lyse the endosomal membranes. LAH4 derivatives also help in cellular transduction using lentiviruses. Here, we compare the DNA transfection activities of LAH4 derivatives, which vary in overall charge and/or the composition in the hydrophobic core region. In addition, LAH4 is shown to mediate the transport of functional β-galactosidase, a large tetrameric protein of about 0.5 MDa, into the cell interior. Interestingly, the LAH1 peptide efficiently imports this protein, while it is inefficient during DNA transfection assays. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.