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. 2020 Sep;13(9):100798.
doi: 10.1016/j.tranon.2020.100798. Epub 2020 May 23.

A Dodecapeptide Selected by Phage Display as a Potential Theranostic Probe for Colon Cancers

Moon Hwa Kwak  1 , Gawon Yi  2 , Seung Mok Yang  1 , Younghee Choe  1 , Sangkee Choi  3 , Hye-Soo Lee  4 , Eunha Kim  3 , Yong-Beom Lim  4 , Kun Na  5 , Myung-Gyu Choi  6 , Heebeom Koo  7 , Jae Myung Park  8
Affiliations

A Dodecapeptide Selected by Phage Display as a Potential Theranostic Probe for Colon Cancers

Moon Hwa Kwak et al. Transl Oncol. 2020 Sep.

Abstract

Aim: Colon cancer is one of the leading causes of cancer-related mortality. However, specific biomarkers for its diagnosis or treatment are not established well.

Methods: We developed a colon-cancer specific peptide probe using phage display libraries. We validated the specificity of this probe to colon cancer cells with immunohistochemical staining and FACS analysis using one normal cell and five colon cancer cell lines.

Results: This peptide probe maintained binding affinity even after serum incubation. For therapeutic applications, this peptide probe was conjugated to hematoporphyrin, a photosensitizer, which showed a significantly enhanced cellular uptake and high photodynamic effect to kill tumor cells. As another application, we made a nanoparticle modified from the peptide probe. It efficiently delivered SN-38, an anticancer drug, into tumor cells, and its tumor-targeting ability was observed in vivo after intravenous injection to the same xenograft model.

Conclusion: The noble dodecapeptide probe can be a promising candidate for both colon tumor diagnosis and targeted drug delivery.

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Conflict of interest statement

Declaration of Competing Interest The authors declare no potential conflicts of interest.

Figures

Figure 1
Figure 1
Binding affinity studies in colon cancer cells. (A) Immunohistochemical staining was performed using Alexa 488 in order to confirm the binding affinity of the phage clone to five colon cancer cells and a normal cell line. (B) Five colon cancer cell lines and CCD841 cells were subjected to immunofluorescence staining to confirm the cell binding ability of the L20 peptide. L20 peptide was labeled with FITC, and cells were stained with DAPI.
Figure 2
Figure 2
Serum stability test of L20 peptide in (A) human and (B) mouse serum. Immunohistochemical staining was performed. (A) Fluorescence was observed even after incubation of the L20 peptide for 30 minutes in human serum. (B) The L20 peptide adherence to mouse colon cancer cells was present even after incubating the L20 peptide for 60 minutes in mouse serum.
Figure 3
Figure 3
Cell imaging with L20-conjugated HPP. (A) Fluorescence image of HCT116 cells after treatment of free HPP, (B) fluorescence image of HCT116 cells after treatment of L20-conjugated HPP, (C) fluorescence image of CCD841 cells after treatment of free HPP, (D) fluorescence image of CCD841 cells after treatment of L20-conjugated HPP. Scale bar means 20 μm.
Figure 4
Figure 4
Cell survival assay after photodynamic therapy using free and L20-conjugated HP. (A) MTT assay 16 hours after laser (4 J/cm2), (B) MTT assay 16 hours after laser irradiation (2 J/cm2), and (C) dark toxicity.
Figure 5
Figure 5
L20 peptide-modified nanoparticles and their in vitro test. (A) Illustration and chemical structure (DSPE-PEG-L20), (B) DLS and TEM image, (C) cell binding images, and (D) MTT (SN38-loaded NPs).
Figure 6
Figure 6
In vivo biodistribution of L20 peptide-modified nanoparticles. (A) Whole body images of mice after intravenous injection of L20-conjugated NPs and fluorescence intensities in tumor site. (B) Ex vivo images of the major organs and tumors from mice. (C) Fluorescence images of sliced tumor tissues.
Figure 7
Figure 7
Structural modeling and MD simulation of L20 peptide. (A) Calculated structure of the L20 peptide using Maestro software package. (B) A helix wheel diagram representation of L20 and the plausible model of the helix bundle formation in cell membrane.
See this image and copyright information in PMC

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