Perspective and challenges of organoid-based high-throughput
peptide screening platforms
According to the methods of organoid-based small molecule drug screening
platforms, we believe that organoids can also be applied in the
high-throughput screening of peptides. This section presents the
perspective and challenges of applying organoids in peptide screens
based on their characteristics.
Owing to their remarkable binding affinity and specificity, peptides are
suitable for transporting cytotoxic drugs to disease
lesions138-140. However, there is still a wide gap
between research and clinical application of peptide drugs. For example,
the discovery of organ-specific targeted peptides may further decrease
the side effect of this treatment modality.
Given that peptides can be
rapidly synthesized and easily modified, researchers can generate
peptide libraries and perform high-throughput screening of the optimal
candidates using organoid models, which is a promising direction for
developing more effective peptide-based drugs3.
Moreover, for peptides that deliver drugs in vivo, although the
interactions are present on the cell surface, they may not alter the
cell phenotype and cause a therapeutical effect. In RPT, the “cold”
radionuclides without radioactivity are often used to label the peptide
and prescreen the peptides with high binding affinity to reduce the
experimental cost. The commonly used method, CellTiter-Glo assay,
determines drug efficacy by measuring cell viability, which is not
suitable for assessing the binding affinity of peptide candidates.
Multiple approaches are used for traditional specific peptide discovery,
such as using fluorescent labeled peptides. The future direction is to
modify the existing methods and
develop appropriate assays that match the high-throughput organoid
culture technology, for direct assessment of peptide affinity. In
addition, due to the difference in the emission range of
radionuclides141-143, the peptide-radionuclide
conjugates not bound to the cell surface but located near the cells
should be investigated to determine whether they can kill the targeted
cells, which may cause false-positive results during screening.
Peptides hold high biological and chemical diversity; and most targeting
peptides exhibit therapeutic effects on diseases5. For
example, the expression of immune checkpoint proteins (PD-1 and PD-L1)
can be suppressed by targeted peptides for increasing the immune
response to kill tumor cells 144-148. However, the
high diversity of nature product peptides poses a challenge to the
identification of the above-mentioned tumor neoantigens and bioactive
peptides derived from venoms, which are produced by many kinds of
organisms, such as plants, snakes, spiders and insects, and are found to
interact with tumors and modulate the proliferation, migration, immune
response of tumor cells, suggesting potential therapeutic agents for
cancers149-155. Therapeutic peptides are promising
candidates for treating various diseases, and more effective peptide
drugs are required to address clinical demands. Thus, high-throughput
screening of therapeutic peptides using organoid technology may
significantly improve the efficiency for identifying and uncovering the
optimal peptides with high binding affinity and ideal therapeutic
effects. Furthermore, although peptides are low-cytotoxic drugs compared
to small molecules and antibodies, healthy organoid models can also be
used to examine their side effects on normal cells, which is one of the
advantages of organoid technology.