[Application of Asn-Gly-Arg sequence based cyclic peptides for targeted tumor therapy]

Area of Science:

• Oncology
• Pharmacology
• Bioconjugation Chemistry

Background:

• Peptide-drug conjugates offer targeted delivery of chemotherapeutics.
• The NGR peptide sequence targets CD13 receptors, often overexpressed on tumor cells.
• Integrins are cell surface receptors involved in cell adhesion and signaling.

Purpose of the Study:

• To evaluate the in vivo antitumor efficacy of two NGR-containing peptide-daunomycin conjugates.
• To compare the efficacy of conjugates targeting CD13+ (Kaposi's sarcoma) and CD13- (colon adenocarcinoma) tumor models.
• To assess the safety and mechanism of action of these novel conjugates.

Main Methods:

• Synthesis and characterization of two peptide-daunomycin conjugates (Dau=Aoa-GFLGK(cyclo[KNGRE]-GG)-NH2 (1) and Dau=Aoa-GFLGK(cyclo[NleNGRE]-GG)-NH2 (2)).
• In vivo antitumor studies in SCID mice bearing CD13+ Kaposi's sarcoma and CD13- HT-29 colon adenocarcinoma xenografts.
• Assessment of tumor growth inhibition, proliferation index, and neovascularization.
• Evaluation of toxic side effects in comparison to free daunomycin.

Main Results:

• Both conjugates significantly inhibited tumor growth in both Kaposi's sarcoma and colon adenocarcinoma models.
• Conjugate 1, with a stable NGR sequence, was more potent against CD13+ tumors.
• Conjugate 2, with an isoDGR sequence, showed higher efficacy against CD13- tumors, suggesting integrin binding.
• Conjugates exhibited lower toxicity and reduced tumor proliferation and neovascularization compared to free daunomycin.

Conclusions:

• Peptide-daunomycin conjugates are effective in inhibiting tumor growth in vivo.
• The NGR and isoDGR sequences confer differential targeting capabilities based on CD13 expression and integrin binding.
• These conjugates represent a promising strategy for targeted cancer therapy with improved safety profiles.