Low molecular weight protamine (LMWP): A nontoxic protamine substitute and an effective cell-penetrating peptide

CPP-Assisted Intracellular Drug Delivery, What Is Next?

“…Subsequently, various classes of CPPs, including arginine/lysine-rich cationic peptides, LMWP, Penetratin and VP22 [15,24,31,32,33,34], as well as amphipathic peptides such as MAP, MPG, pep-1, etc., were also reported and utilized in either remarkable intracellular delivery strategies or the successful application in medical and biological field [17,19,25,26,27,35,36,37,38,39,40,41,42,43,44,45,46,47,48]. Via covalent linkage or non-covalent charge-associated aggregation, linkage, both in vitro and in vivo results demonstrated that CPPs could assist the delivery of virtually all types of molecular cargos including proteins [2,16,20,26,46,49,50,51,52,53,54,55], nucleic acids [33,35,36,56,57,58,59,60], and nano-carriers such as magnetic iron oxide nanoparticles (MION) [61,62,63,64,65,66,67,68] into cells.…”

“…In 1999, a recombinant TAT-β-galactosidase fusion protein that could cross through BBB following intraperitoneal injection was first reported by Dowdy and co-workers [23], which actually set up the tune to realize the milestone goal in pharmaceutical research in achieving intracellular delivery of protein drugs. Recently, we reported the successful synthesis of cell-permeable gelonin (Gel), a toxin that could inhibit protein translation in cells, with cationic CPPs (i.e., TAT and LMWP) via either chemical conjugation (CPP-Gel) or genetic recombinant method (rGel), to overcome the inability of gelonin to internalize cells [31]. Unlike native gelonin that could not enter cells to exert its cytotoxic effects, significant inhibition on tumor growth was observed in mice treated with CPP-Gel or rGel; suggesting that incorporation of CPP would dramatically enhance the cytotoxic activity of gelonin.…”

“…In a recent study, we demonstrated the plausibility of this approach by physical adsorption of the anionic pSV-β-galactosidase plasmid with LMWP. Expression of β-galactosidase in animals was found to be significantly augmented with very minor cell cytotoxicity, when comparing with the use of cationic protamine or polyethyleneimine (PEI) as the β-galactosidase gene carrier [31]. Moreover, the LMWP/siRNA complex was also used for cancer therapy, as the fluorescent-tagged LMWP/siRNAs complexes were found to localize in the cytoplasm shortly after incubation with the carcinoma cells, resulting in a strong down-regulation of the target gene [72].…”

“…In order to safe control this CPP “Trojan Horse”-led intracellular drug delivery, “smart” systems were developed using the heparin/protamine-regulated prodrug protection/deprotection strategy [17,31,52]. This system was made up of two major components: (a) a targeting compartment that consisted of a heparin-linked tumor-targeting unit such as an antibody (Figure 3a) or the magnetic iron oxide nanoparticle (MION) carrier (Figure 3b); and (b) a drug compartment composed of a covalent conjugate of the polycationic CPPs (e.g., TAT and LMWP) and macromolecular drugs (e.g., protein and siRNA) in achieving potent intra-tumoral drug therapy [66,67,68,98,99].…”

Effective Delivery of Male Contraceptives Behind the Blood-Testis Barrier (BTB) – Lesson from Adjudin

“…was found to be effectively delivered to lung, heart muscle, and spleen in vivo [76]. Thus, following the discovery of this stretch of sequence of TAT from 47–57, a 11-amino acid peptide, known as Protein/Peptide Trans-duction Domain (PTD), multiple PTDs have since been identified and designated Cell Penetrating Peptides (CPPs) [77], such as low molecular weight protamine (LMWP) which is an effective CPP [78]. Most PTDs are basic peptides composed of multiple Arg residues between 9 and 20 amino acid residues, and can effectively transport proteins, peptides, siRNA, and siRNA nanoparticles across cell membranes [79].…”