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Rhenium-guanidine complex as photosensitizer: trigger HeLa cell apoptosis through death receptor-mediated,
Shu-Fen He1,2, Jia-Xin Liao1, Min-Ying Huang1
1School of Pharmacy, Guangdong Medical University, Dongguan 523808, China.
Abstract:
The growing evidence over the past few decades has indicated that the photodynamic antitumor activity of transition metal complexes, and Re(I) compounds are potential candidates for photodynamic therapy. This study reports the synthesis, characterization, and anti-tumor activity of three new Re(I)-guadinium complexes. Cytotoxicity tests reveal that complex Re1 increased cytotoxicity by 145-fold from IC50 > 180 μM in the dark to 1.3 ± 0.7 μM following 10 min of light irradiation (425 nm) in HeLa cells. Further, the mechanism by which Re1 induces apoptosis in the presence or absence of light irradiation was investigated, and results indicate that cell death was caused through different pathways. Upon irradiation, Re1 first accumulates on the cell membrane and interacts with death receptors to activate the extrinsic death receptor-mediated signaling pathway, and then is transported into the cell cytoplasm. Most of the intracellular Re1 locates within mitochondria, improving the reactive oxygen species level, and decreasing mitochondrial membrane potential and ATP levels, and inducing the activation of caspase-9 and, thus, apoptosis. Subsequently, the residual Re1 can translocate into the cell nucleus, and activates the p53 pathway, causing cell cycle arrest and eventually cell death.
Insights
New rhenium(I) complexes show potent photodynamic antitumor activity. Complex Re1 significantly enhances cancer cell death via apoptosis, demonstrating promise for photodynamic therapy applications.
Area of Science:
- Inorganic Chemistry
- Medicinal Chemistry
- Photochemistry
Background:
- Transition metal complexes, particularly Re(I) compounds, are explored for photodynamic therapy due to their antitumor potential.
- Photodynamic therapy (PDT) offers a targeted approach to cancer treatment by utilizing photosensitizers activated by light.
Purpose of the Study:
- To synthesize and characterize novel Re(I)-guanidinium complexes for potential anticancer applications.
- To evaluate the photodynamic antitumor activity and elucidate the mechanism of action of these complexes.
Main Methods:
- Synthesis and characterization of three new Re(I)-guanidinium complexes.
- In vitro cytotoxicity assays (IC50 determination) in HeLa cells, with and without light irradiation.
- Mechanistic studies involving cellular localization, reactive oxygen species (ROS) generation, mitochondrial function assessment, and apoptosis pathway analysis (caspase-9, p53).
Main Results:
- Complex Re1 exhibited a 145-fold increase in cytotoxicity upon light irradiation (425 nm), with IC50 decreasing from >180 μM to 1.3 ± 0.7 μM.
- Irradiated Re1 localized to the cell membrane, activating the extrinsic death receptor pathway before entering the cytoplasm.
- Intracellular Re1 accumulated in mitochondria, increasing ROS, decreasing mitochondrial potential and ATP, activating caspase-9, and inducing apoptosis, followed by nuclear translocation and p53 pathway activation.
Conclusions:
- The synthesized Re(I)-guanidinium complexes, particularly Re1, demonstrate significant photodynamic antitumor activity.
- Re1 induces cancer cell death through distinct pathways dependent on light irradiation, involving both extrinsic death receptor and intrinsic mitochondrial pathways, ultimately leading to apoptosis and cell cycle arrest.
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