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Linker-dependent variations in the tumoricidal activity of DZ-1-dihydroartemisinin conjugate formats
Farzaneh Vafaeinik1, Sarah Helmueller1, Yi Zhang1
1Cedars-Sinai Cancer Institute and Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
Background:
Cancer remains a leading cause of death worldwide, and many therapies are limited by poor tumor specificity, systemic toxicity, and drug resistance. Tumor-targeted strategies that enhance drug accumulation while minimizing off-target effects are therefore essential. We hypothesized that conjugating dihydroartemisinin (DHA) to the tumor-targeting near-infrared dye DZ-1 would improve tumor-selective accumulation, promote mitochondrial localization, and enhance reactive oxygen species (ROS)-mediated cytotoxicity. We also investigated how linker chemistry influences drug stability and therapeutic efficacy.
Methods:
Three types of linkers (ether, ester, and carbamate) were used to conjugate DZ-1 with dihydroartemisinin (DHA). The tumoricidal efficacy of these DZ-1-DHA conjugates was evaluated in HCT116 and BxPC3 cells. Cytotoxicity was assessed using the trypan blue exclusion assay. Apoptosis was analyzed by TUNEL staining and immunoblotting. Drug accumulation was compared among the conjugates. Mitochondrial membrane potential was assessed using JC-1 staining, and ROS generation was measured using DCF, MitoSOX, and Mito-TEMPO assays.
Results:
Ester-linked DZ-1-DHA showed the most potent, dose-dependent cytotoxicity in both HCT116 and BxPC3 cells. Apoptosis was confirmed by immunoblotting and TUNEL assays. Fluorescence microscopy revealed that the ester-linked conjugate effectively accumulated in mitochondria, efficiently generated reactive oxygen species (ROS), and disrupted mitochondrial membrane potential.
Conclusions:
Our findings demonstrate that linker chemistry critically influences DZ-1-DHA accumulation and mitochondrial ROS generation, which in turn determine tumoricidal efficacy. Among the conjugates, the ester-linked DZ-1-DHA exhibited superior anticancer activity. These results provide mechanistic insight and highlight linker optimization as a key design principle for the development of next-generation tumor-targeted artemisinin therapeutics.
Insights
Optimizing linker chemistry for dihydroartemisinin (DHA) conjugates enhances tumor targeting and efficacy. Ester-linked DZ-1-DHA demonstrated superior anticancer activity by improving mitochondrial accumulation and reactive oxygen species generation.
Area of Science:
- Bioconjugation Chemistry
- Cancer Therapeutics
- Mitochondrial Targeting
Background:
- Cancer therapies face challenges with tumor specificity, toxicity, and drug resistance.
- Tumor-targeted strategies are crucial for enhancing drug delivery and minimizing side effects.
- Dihydroartemisinin (DHA) conjugated to a near-infrared dye (DZ-1) was explored for improved tumor accumulation and cytotoxicity.
Purpose of the Study:
- To synthesize and evaluate DZ-1-DHA conjugates using different linkers (ether, ester, carbamate).
- To assess the impact of linker chemistry on drug stability, tumor cell accumulation, and therapeutic efficacy.
- To investigate the mechanism of action, including mitochondrial localization and reactive oxygen species (ROS) generation.
Main Methods:
- Synthesis of three DZ-1-DHA conjugates with varying linker chemistries.
- Evaluation of tumoricidal efficacy in HCT116 and BxPC3 cancer cell lines.
- Assessment of apoptosis, drug accumulation, mitochondrial membrane potential, and ROS generation.
Main Results:
- The ester-linked DZ-1-DHA conjugate exhibited the most potent, dose-dependent cytotoxicity.
- Apoptosis was confirmed, and the ester-linked conjugate showed enhanced mitochondrial accumulation and ROS generation.
- Disruption of mitochondrial membrane potential was observed with the ester-linked conjugate.
Conclusions:
- Linker chemistry significantly impacts the accumulation and mitochondrial ROS generation of DZ-1-DHA conjugates, thereby influencing anticancer efficacy.
- The ester linkage provides a promising strategy for developing effective tumor-targeted artemisinin therapeutics.
- Optimizing linker chemistry is a key principle for next-generation cancer drug development.
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