Ternary Copper (II) Complex Induced Apoptosis and Cell Cycle Arrest in Colorectal Cancer Cells

The lack of specificity, severe side effects, and development of drug resistance have largely limited the use of platinum-based compounds in cancer treatment. Therefore, copper complexes have emerged as potential alternatives to platinum-based compounds.

Ternary copper (II) complex incorporated with 1-10-phenanthroline and L-tyrosine was investigated for its anti-cancer effects in HT-29 colorectal cancer cells.

Cytotoxic effects of ternary copper (II) complex in HT-29 cells was evaluated using MTT assay, Real-Time Cell Analysis (RTCA) and lactate dehydrogenase (LDH) assay. Cell cycle analysis was performed using flow cytometry. Apoptosis induction was studied by Annexin V-FITC/Propidium Iodide (PI) staining and mitochondrial membrane potential analysis (JC-10 staining) using flow cytometry. Intracellular Reactive Oxygen Species (ROS) were detected by DCFH-DA assay. The expression of proteins involved in the apoptotic signalling pathway (p53, caspases, and PARP-1) was evaluated by western blot analysis.

Ternary copper (II) complex reduced the cell viability of HT-29 cells in a time- and dose-dependent manner, with IC50 of 2.4 ± 0.4 and 0.8 ± 0.04 μM at 24 and 48 hours, respectively. Cell cycle analysis demonstrated induction of S-phase cell cycle arrest. Morphological evaluation and Annexin V-FITC/PI flow cytometry analysis confirmed induction of apoptosis that was further supported by cleavage and activation of caspase-8, caspase-9, caspase-3, and PARP- 1. Mutant p53 was also downregulated in a dose-dependent manner. No LDH release, mitochondrial membrane potential disruption, and ROS production were observed.

Ternary copper (II) complex holds great potential to be developed for colorectal cancer treatment.