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SEPTEMBER 02-3. 幹細胞與轉譯癌症 研究所 SEPTEMBER

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(1) 撰稿者：游正博特聘講座教授暨所長 Identification of these peptides enabled us to delineate the GRP78 binding motif as

John Yu, M.D., Ph.D. Pro-X1-Leu-X2, where X1 is an amino acid with a hydrophobic side chain, and X2 is
either Pro or an aromatic amino acid.

We further examined the ability of

Structure-based design for binding peptides in anti-cancer therapy. the peptides to target cancer cells
through in vitro binding studies with

The conventional anticancer therapeutics usually lack cancer specificity, leading cell lines and clinical cancer specimens,
to damage of normal tissues. Ideally, anticancer therapeutics carrying payloads of and in vivo tumor imaging and

drugs equipped with cancer targeting peptides can act like “guided missiles” with the targeted chemotherapeutic studies.
capacity of targeted delivery toward many types of cancers. Peptides are amenable MicroSPECT/CT imaging revealed

for conjugation to many payloads for functionalization, thereby improving drug significantly greater uptake of 188Re-

delivery and cellular uptake in cancer-targeting therapies (Biomaterials 2018, 156 liposomes linked to these peptides as
1-15). In these studies, the development and application of strategies for structure- compared with non-targeting 188Re-

based design of cancer-targeting peptides against GRP78 are explored through liposomes at 48 hours after injection.

molecular docking and in silico analysis.We investigate the peptide pharmacokinetics Conjugation with these peptides also
and targeting delivery, including molecular docking studies, features that provide significantly increased the therapeutic

advantages for in vivo use, and properties that influence the cancer-targeting ability. efficacy of Lipo-Dox.

Currently, we are Notably, these peptides could bind to a stem cell subpopulation in xenografts of
developing new anti- primary breast cancer. The structure-based optimization strategy for protein-binding

cancer therapeutics peptides described here may be useful for developing peptide drugs for cancer imaging

conjugated with this and therapy.
cancer targeting

peptides. Extracellular location of the peptide-binding domain of GRP78 on cancer cells:

In order to examine that whether the peptide binding domain of GRP78 is exposed
Structure-based optimization of GRP78-binding peptides that enhances efficacy in extracellularly, we developed a detecting method using cell-surface biotinylation and
cancer imaging and therapy. mass-spec analysis. The biotinylated GRP78 on the cell surface was purified using

(Biomaterials 2016, 94:31; Biomaterials 2018, 156: 1-15)
streptavidin column followed by in-gel chymotrypsin digestion. The resulting peptides
We first utilized a peptide-binding protein database to identify GRP78 as a target were examined by C18 reverse-phase nano-liquid chromatography coupled to an

protein for a cancer cell-binding lead peptide. Subsequently, we used homologous Orbitrap Fusion tandem mass spectrometer run in data-dependent MS/MS mode.

modeling and molecular docking, and a new protein-ligand scoring program, HotLig, By comparing the fragmentation pattern of a biotinylated peptide with in silico
to identify a series of anti-cancer peptides targeting a specific peptide-binding domain fragmentation pattern of the unmodified peptide, the site of biotinylation can be

of GRP78. Binding of these peptides to GRP78 was confirmed and optimized using an assigned to a specific lysine residue. Tandem mass spectra such as this allowed us to
oriented immobilization technique for the Biacore system. determine sites of biotinylation on the GRP78 proteins.

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