Screening and characterization of a novel high‐efficiency tumor‐homing cell‐penetrating peptide from the buffalo cathelicidin family

Abstract

Targeted delivery of antitumor drugs is especially important for tumor therapy. Cell‐penetrating peptides (CPPs) have been shown to be very effective drug carriers for tumor therapy. However, most CPPs lack tumor cell specificity. Here, we identified a highly efficient CPP, CAT, from the newly identified buffalo‐derived cathelicidin family, which exhibits a preferential binding capacity for multiple tumor cell lines and delivers carried drug molecules into cells. CAT showed an approximately threefold to sixfold higher translocation efficiency than some reported cell‐penetrating antimicrobial peptides, including the well‐known classical CPP TAT. Moreover, the delivery efficiency of CAT was greater in a variety of tested tumor cells than in normal cells, especially for the human hepatoma cell line SMMC‐7721, for which delivery was 7 times more efficient than the normal human embryonic lung cell line MRC‐5, according to fluorescent labeling experiment results. CAT was conjugated to the Momordica charantia‐derived type‐I ribosome‐inactivating protein MAP 30, and the cytotoxicity of the MAP 30‐CAT fusion protein in the tumor cell line SMMC‐7721 was significantly enhanced compared with that of the unconjugated MAP 30. The IC50 value of MAP 30‐CAT was approximately 83 times lower than the IC50 value of the original MAP 30. Interestingly, the IC50 value of MAP 30 alone for MRC‐5 was approximately twofold higher than the value for SMMC‐7721, showing a small difference. However, when MAP 30 was conjugated to CAT, the difference in IC50 values between the two cell lines was significantly increased by 38‐fold. The results of the flow cytometric detection of apoptosis revealed that the increase in cytotoxicity after CAT conjugation was mainly caused by the increased induction of apoptosis by the fusion protein. These results suggest that CAT, as a novel tumor‐homing CPP, has great potential in drug delivery applications in vivo and will be beneficial to the development of tumor therapeutics.

New generation of cell‐penetrating peptides: Functionality and potential clinical application

“…Additionally, they show higher translocation efficiency than most other CPPs. Therefore, CAT is considered a novel tumor homing CPP with great potential for selective drug delivery 74 …”

‘Getting Better’—Is It a Feasible Strategy of Broad Pan-Antiherpesviral Drug Targeting by Using the Nuclear Egress-Directed Mechanism?

“…In this case, the question had to be experimentally addressed as to whether the design of an NEC-binding synthetic peptide would ensure cellular uptake and the crossing of cell membranes. To this end, the previously reported amino acid sequences of cell-penetrating peptides (CPPs [ 94 , 115 , 116 , 117 , 118 , 119 , 120 , 121 ]) could be utilized to generate synthetic chimeras that included three different functions [ 94 ]: (i) a 29-mer peptide, representing the minimal binding fragment of HCMV pUL53 (α-helical N-terminal hook-like region) to its NEC counterpart pUL50 (groove), was synthetically fused with (ii) a small cationic or amphipathic CPP sequence, in connection with (iii) the autologous pUL53 nuclear localization signal (NLS, amino acids 18–27 [ 122 ]). These model peptides, termed NLS-CPP-Hook, were then analyzed for the specific properties of the inhibition of core NEC assembly and putative antiviral potential.…”

Cell-Penetrating and Targeted Peptides Delivery Systems as Potential Pharmaceutical Carriers for Enhanced Delivery across the Blood–Brain Barrier (BBB)

“…Another peptide myristic acid-conjugated transportan (TP) conjugated to transferrin receptor-targeting peptide (myr-TP-Tf) was successfully encapsulated, and siRNA was delivered to brain endothelial cells and glioma cells [ 137 ]. Notwithstanding these heartening outcomes, the use of siRNA and the advances in novel CPPs anticipated for targeted delivery have many challenges [ 138 ].…”