New generation CPPs show distinct selectivity for cancer and noncancer cells

Abstract

In the last three decades, many new cell‐penetrating peptides (CPPs) were developed that exhibited enhanced cell selectivity. Thus, we aimed to validate the tumor cell selectivity of peptides from this new generation, namely fragments mini‐crotamine and mini‐maurocalcine. Both of these peptides are derived from venoms. Furthermore, we studied an analog of the classical CPP HIV‐TAT(47‐57) with alternating chirality of Arg residues. To allow covalent coupling of cargoes or fluorophores, a cysteine residue was introduced to the N‐terminus of the synthesized peptides. The therapeutic antibody trastuzumab conjugated to different fluorescent dyes was used for internalization studies. Comparison of uptake efficiencies revealed that CPPs of the new generation are in contrast to MPG‐peptides, nearly unable to internalize the noncovalently formed complexes with trastuzumab. Interestingly, the fluorescent derivative of the crotamine fragment was mainly observed in a subpopulation of breast cancer cells, whereas it was homogenously distributed in fibrosarcoma, colon cancer, and noncancerous endothelia cells. Thus, the fluorescent crotamine fragment reported herein is a potent theranostic tool for image‐guided applications. This peptide can be used to pinpoint the level of heterogeneity present within tumors and aid in the generation of therapeutics that target heterogenic subpopulations.

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

“…Furthermore, the ability of crotamine to transport cargoes both in vitro and in vivo, in particular into actively proliferating cells, 59 makes crotamine and its derivatives suitable markers of actively proliferating cells, such as cancer cells. For instance, very recently Tansi et al 23 found that a fluorescent derivative of Cys‐[4‐Ser‐crotamine(Δ10–37)] could reveal tumor micro‐heterogeneity by preferential internalization into proliferating breast cancer cells, whereas it was homogeneously distributed in fibrosarcoma, colon cancer, and noncancerous endothelial cells. Thus, this peptide can be used to determine the level of heterogeneity within tumors.…”

“…Indeed, to highlight tumors or inflamed tissues, marker molecules must be conjugated. For instance, fluorescent labels can be used as markers, 21 especially those emitting in the near‐infrared (NIR) region, 22,23 together with metal‐chelating complexes for sensitive NMR imaging 24 and radionuclides 25 . Therefore, imaging with fluorescence‐labeled and tissue‐specific CPPs can be very helpful for visualizing the margin between healthy and diseased tissues during surgery 4 …”

Cell-Penetrating Peptides Derived from Animal Venoms and Toxins

“…Overall, in a series of sequential studies, replacing the cysteine residue at position 4 in NrTP-1 for a serine resulted in an analog, namely NrTP-6 (YKQSHKKGGKKGSG), with a significantly improved performance in terms of its interaction with biomembranes, penetrability, cargo transportation of large macromolecules, concentration-independent internalization kinetics and negligible cytotoxicity to healthy cells [148][149][150][151]. The NrTP-6 analog, in which the near-infrared dye DY676 was coupled to an extra N-terminal cysteine residue in NrTP-6 (DY676-Cys-NrTP6, "mini-crotamine") efficiently penetrated and accumulated in certain lines and cancer cell populations, rendering this NrTP version a promising theranostic probe for imaging cancer heterogeneity and delivery of chemotherapeutics into subpopulations of cancer cells [152].…”

From Animal Poisons and Venoms to Medicines: Achievements, Challenges and Perspectives in Drug Discovery

“…This toxin is specifically uptaken by actively proliferating cells, being able to permeate several lineages in vitro (Nascimento et al, 2007). Additionally, several molecules based on crotamine structure, including fluorescent derivatives (Tansi et al, 2019) and functionalized with gold nanoparticles (Karpel et al, 2018), for instance, are being developed. Crotamine and its analogues have been tested in healthy and tumorous cell lines, and the results indicate they can be used as selective delivery tools of anticancer molecules (Mambelli-Lisboa et al, 2018).…”