[Lys3]-Bombesin

Product Name: [Lys3]-Bombesin

Sequence One Letter Code: Pyr-QKLGNQWAVGHLM-NH2

Sequence Three Letter Code: Pyr-Gln-Lys-Leu-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH2

Cas No: 66839-66-5

Chemical Formula:C71H110N22O18S

Molecular Weight: 1592

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Cancer Disease Research

SMILES: CC(C)CC(C(=O)NCC(=O)NC(CC(=O)N)C(=O)NC(CCC(=O)N)C(=O)NC(CC1=CNC2=CC=CC=C21)C(=O)NC(C)C(=O)NC(C(C)C)C(=O)NCC(=O)NC(CC3=CN=CN3)C(=O)NC(CC(C)C)C(=O)NC(CCSC)C(=O)N)NC(=O)C(CCCCN)NC(=O)C(CCC(=O)N)NC(=O)C4CCC(=O)N4

IUPAC: N-[6-amino-1-[[1-[[2-[[4-amino-1-[[5-amino-1-[[1-[[1-[[1-[[2-[[1-[[1-[(1-amino-4-methylsulfanyl-1-oxobutan-2-yl)amino]-4-methyl-1-oxopentan-2-yl]amino]-3-(1H-imidazol-5-yl)-1-oxopropan-2-yl]amino]-2-oxoethyl]amino]-3-methyl-1-oxobutan-2-yl]amino]-1-oxopropan-2-yl]amino]-3-(1H-indol-3-yl)-1-oxopropan-2-yl]amino]-1,5-dioxopentan-2-yl]amino]-1,4-dioxobutan-2-yl]amino]-2-oxoethyl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]-2-[(5-oxopyrrolidine-2-carbonyl)amino]pentanediamide

INCHIKEY: DXMFSGIDMUPBCC-UHFFFAOYSA-N

INCHI:

InChI=1S/C71H110N22O18S/c1-35(2)25-48(90-63(103)44(15-11-12-23-72)87-65(105)46(16-19-53(73)94)88-64(104)45-18-21-56(97)83-45)62(102)79-32-57(98)85-52(29-55(75)96)70(110)89-47(17-20-54(74)95)66(106)92-50(27-39-30-78-42-14-10-9-13-41(39)42)67(107)82-38(7)61(101)93-59(37(5)6)71(111)80-33-58(99)84-51(28-40-31-77-34-81-40)69(109)91-49(26-36(3)4)68(108)86-43(60(76)100)22-24-112-8/h9-10,13-14,30-31,34-38,43-52,59,78H,11-12,15-29,32-33,72H2,1-8H3,(H2,73,94)(H2,74,95)(H2,75,96)(H2,76,100)(H,77,81)(H,79,102)(H,80,111)(H,82,107)(H,83,97)(H,84,99)(H,85,98)(H,86,108)(H,87,105)(H,88,104)(H,89,110)(H,90,103)(H,91,109)(H,92,106)(H,93,101)

Source / Species: toad

Conjugation: Unconjugated

Code Nacres: NA.26

Application: [Lys3]-Bombesin is a modified bombesin analog engineered to retain high-affinity binding to the gastrin-releasing peptide receptor (GRPR). GRPR is overexpressed in several malignancies, including prostate and small cell carcinomas. The Lys³ substitution enhances functional versatility for conjugation and imaging applications. This peptide has been widely investigated as a targeting ligand for PET imaging of GRPR-positive tumors. In addition, conjugated formats have demonstrated immune effector recruitment and targeted cytotoxicity in preclinical models. [Lys3]-Bombesin is broadly applied in oncology research for receptor-targeted imaging, drug delivery, and tumor biology studies.

Current Research: [Lys³]-Bombesin is a modified analog of bombesin designed to retain high-affinity binding to the gastrin-releasing peptide receptor (GRPR) while introducing enhanced functional versatility through a lysine substitution at position 3. Bombesin is a 14–amino acid peptide originally isolated from amphibian skin that shares structural and functional homology with mammalian gastrin-releasing peptide (GRP). GRPR, a class A G protein–coupled receptor (GPCR), is overexpressed in multiple malignancies, including prostate carcinoma, small cell lung carcinoma, breast cancer, and gastrointestinal tumors. As such, [Lys³]-Bombesin serves as a valuable targeting ligand in oncology research. GRPR Biology and Signaling GRPR activation regulates mitogenic and survival signaling pathways in tumor cells. Upon ligand binding, the receptor primarily couples to G_q proteins, activating phospholipase C, generating inositol trisphosphate (IP₃), and elevating intracellular calcium levels. Downstream signaling cascades include PKC activation, MAPK/ERK pathway engagement, and modulation of gene expression associated with cell proliferation and migration. Overexpression of GRPR in certain tumor types makes it an attractive molecular target for imaging and therapeutic delivery strategies. Targeted engagement of GRPR enables selective localization to malignant tissues with limited off-target distribution in normal cells. Structural Modification and Functional Versatility The Lys³ substitution introduces a reactive side chain that can be exploited for conjugation to imaging agents, cytotoxic payloads, chelators, or nanoparticles. Importantly, this modification preserves the C-terminal receptor-binding domain responsible for high-affinity GRPR interaction. The presence of a lysine residue allows straightforward coupling through amide bond formation, enabling synthesis of radiolabeled or fluorescent derivatives without compromising receptor specificity. This structural adaptability underlies its broad application in molecular imaging and targeted therapy development. Applications in Molecular Imaging [Lys³]-Bombesin has been extensively studied as a targeting ligand for positron emission tomography (PET) imaging of GRPR-positive tumors. Conjugation to radiometal chelators such as DOTA or NOTA permits labeling with radionuclides including ^68Ga, ^64Cu, or ^177Lu for diagnostic and theranostic applications. In preclinical models, radiolabeled [Lys³]-Bombesin derivatives demonstrate: High tumor uptake in GRPR-expressing xenografts Rapid clearance from non-target tissues Receptor-specific binding confirmed by blocking studies These properties support its use in non-invasive tumor detection and receptor expression profiling. Targeted Drug Delivery and Immuno-Oncology Beyond imaging, conjugated forms of [Lys³]-Bombesin have been investigated for targeted drug delivery and immune effector recruitment. By linking cytotoxic agents, immunomodulators, or antibody fragments to the peptide scaffold, researchers can direct therapeutic payloads specifically to GRPR-expressing cancer cells. In experimental systems, such conjugates have demonstrated: Receptor-mediated internalization Enhanced tumor-specific cytotoxicity Potential recruitment of immune effector mechanisms These approaches highlight the versatility of the Lys³ modification for translational oncology research. Applications in Tumor Biology Studies [Lys³]-Bombesin is also used in fundamental cancer research to: Characterize GRPR expression levels Study receptor-mediated signaling cascades Investigate ligand-induced internalization and trafficking Evaluate receptor antagonists and competitive inhibitors Fluorescent or radiolabeled derivatives facilitate quantitative receptor-binding assays and imaging-based analyses. Experimental Advantages High-affinity binding to GRPR Lys³ residue enabling versatile conjugation Suitable for radiolabeling and fluorescence tagging Compatible with imaging and therapeutic applications Applicable in in vitro and in vivo tumor models Research Significance [Lys³]-Bombesin provides a robust and adaptable platform for GRPR-targeted research. Its preserved receptor affinity and conjugation flexibility make it a valuable ligand for molecular imaging, targeted drug delivery, and mechanistic studies of tumor signaling. As GRPR continues to serve as a biomarker and therapeutic target in oncology, [Lys³]-Bombesin remains an important tool in translational cancer research and receptor-focused therapeutic development.