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Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry
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Synthesis, in vitro stability, and antiproliferative effect of d-cysteine modified GnRH-doxorubicin conjugates

Songtao Li1, Hongling Zhao1, Xiaomin Chang2

  • 1Hebei Province Key Laboratory of Research and Development of Traditional Chinese Medicine, Chengde Medical University, Chengde, Hebei, 067000, China.

Journal of Peptide Science : an Official Publication of the European Peptide Society
|November 24, 2018
PubMed

Insights

New GnRH-doxorubicin conjugates show promise for targeted cancer therapy. Conjugate II, targeting GnRH receptors, demonstrated enhanced efficacy and reduced toxicity in preclinical models, suggesting a novel strategy for treating GnRH receptor-positive tumors.

Area of Science:

  • Oncology
  • Pharmacology
  • Bioconjugation Chemistry

Background:

  • Gonadotropin-releasing hormone (GnRH) receptors are overexpressed in various tumors, unlike normal tissues.
  • GnRH analogs can be utilized for targeted delivery of cytotoxic agents, potentially improving anticancer drug uptake and reducing side effects.

Purpose of the Study:

  • To synthesize and evaluate novel GnRH-doxorubicin conjugates for targeted cancer chemotherapy.
  • To assess the metabolic stability, antiproliferative activity, and targeting specificity of these conjugates.

Main Methods:

  • Three GnRH analogs were conjugated with doxorubicin (Dox) using N-succinimidyl-3-maleimidopropionate linker.
  • Metabolic stability was assessed using RP-HPLC in human serum.
  • Antiproliferative activity was evaluated via MTT assay in GnRH receptor-positive MCF-7 cells and GnRH receptor-negative 3T3 cells.

Main Results:

  • The synthesized GnRH-Dox conjugates exhibited improved metabolic stability compared to AN-152.
  • Conjugate II ([d-Cys 6 , desGly 10 , Pro 9 -NHEt]-GnRH-Dox) displayed superior antiproliferative effects on MCF-7 cells than conjugates I and III.
  • Conjugate II showed reduced cytotoxicity against 3T3 cells compared to free Dox, indicating targeted action.

Conclusions:

  • Targeted delivery of conjugate II, mediated by [d-Cys 6 -des-Gly 10 -Pro 9 -NHEt]-GnRH, is a promising strategy for chemotherapy of tumors overexpressing GnRH receptors.
  • This approach offers potential for enhanced efficacy and reduced systemic toxicity in cancer treatment.
Keywords:
antitumor activitygonadotropin-releasing hormonemetabolic stabilitypeptide-drug conjugatesynthesis

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