Macropinocytosis as a Key Determinant of Peptidomimetic Uptake in Cancer Cells

Abstract

Peptides and peptidomimetics represent the middle space between small molecules and large proteinsthey retain the relatively small size and synthetic accessibility of small molecules while providing high binding specificity for biomolecular partners typically observed with proteins. During the course of our efforts to target intracellular protein–protein interactions in cancer, we observed that the cellular uptake of peptides is critically determined by the cell linespecifically, we noted that peptides show better uptake in cancer cells with enhanced macropinocytic indices. Here, we describe the results of our analysis of cellular penetration by different classes of conformationally stabilized peptides. We tested the uptake of linear peptides, peptide macrocycles, stabilized helices, β-hairpin peptides, and cross-linked helix dimers in 11 different cell lines. Efficient uptake of these conformationally defined constructs directly correlated with the macropinocytic activity of each cell line: high uptake of compounds was observed in cells with mutations in certain signaling pathways. Significantly, the study shows that constrained peptides follow the same uptake mechanism as proteins in macropinocytic cells, but unlike proteins, peptide mimics can be readily designed to resist denaturation and proteolytic degradation. Our findings expand the current understanding of cellular uptake in cancer cells by designed peptidomimetics and suggest that cancer cells with certain mutations are suitable mediums for the study of biological pathways with peptide leads.

Alternative approaches to target Myc for cancer treatment

“…As a test shows, uptake of linear peptides, peptide macrocycles, stabilized helices, β-hairpin peptides, and cross-linked helix dimers by cancer cells is positively correlates to their macropinocytosis levels. 121 Generally, cancer cells have demanding nutrient needs to thrive and exhibit high inherent macropinocytosis levels, especially KRAS mutant cells. Thus, it may offer an opportunity to overcome the barrier and deliver structurally-modified peptides or antibody agents to intracellular compartments to target Myc in the circumstances of high basal macropinocytosis level.…”

Peptide-based inhibitors of protein–protein interactions: biophysical, structural and cellular consequences of introducing a constraint

“…In addition, the cell type is undoubtedly important and systematic studies will aid in refining these guidelines; for instance recent studies have shown better uptake observed for conformationally stabilized peptides in cancer cells with upregulated macropinocytosis. 112 It is noteworthy that a significant number of these studies make use of fluorescently labelled peptides which may behave differently to the parent sequence as a consequence of the fluorescent reporter. Making use of novel higher-throughput assays e.g.…”

From Pinocytosis to Methuosis—Fluid Consumption as a Risk Factor for Cell Death

“…For instance, designing of compounds like proteolytically stable peptidomimetics that are taken up by macropinocytosis, but which are able to escape from endosomes, could be used for intracellular biomolecular targeting (Yoo et al, 2020).…”

“…Ruffling of cholesterol-rich membrane microdomains leads to the unselective incorporation of large volumes of extracellular fluid in macropinosomes with a diameter of 0.2 up to 5.0 μm ( Levin et al, 2015 ; Donaldson, 2019 ). Macropinocytosis may occur constitutively or be induced by growth factors, chemokines, microbial products, viruses ( Freeman et al, 2014 ; Marques et al, 2017 ; Canton, 2018 ; Doodnauth et al, 2019 ; Tejeda-Munoz et al, 2019 ), crosslinking of cell surface molecules ( Imamura et al, 2011 ), knockdown of genes ( Choi et al, 2017 ; Fomin et al, 2018 ; Fomin, 2019 ; Su et al, 2021 ), and constitutive expression ( Kasahara et al, 2007 ) or mutations of signal transduction molecules ( Yoo et al, 2020 ). Some cells, like innate immune cells and Ras-transformed cancer cells, are able to perform both forms of macropinocytosis ( Amyere et al, 2000 ; Stow et al, 2020 ).…”

“…For instance, designing of compounds like proteolytically stable peptidomimetics that are taken up by macropinocytosis, but which are able to escape from endosomes, could be used for intracellular biomolecular targeting ( Yoo et al, 2020 ). Likewise, development of versatile drug carriers with a high loading capacity, such as nanoparticles, which are optimized for specific binding to cell surface receptors, and which are favoring both macropinocytic uptake and intracellular release by degradation of their shells, may open new ways for, e.g., cancer therapy.…”