Investigating the Cytotoxic, Apoptotic, Treatment-Resistant, and Inflammatory Response Properties of a Gold(III) Complex Containing a Tetradentate Schiff Base Ligand

Considering the cytotoxic properties of Schiff base ligands, we re-synthesized a gold(III) complex with a tetradentate Schiff base ligand and investigated its cytotoxic effects using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method and sulforhodamine B staining method. The results showed that the gold(III) Schiff base complex can inhibit the growth of Chinese hamster ovary (CHO) cancer cell lines. However, unlike cisplatin, it does not induce cell death in NIH 3T3 normal cells. Real-time polymerase chain reaction (PCR) results revealed that the gold(III) Schiff base complex increased the Bak1/Bclx ratio in CHO cell line by 3.53-fold compared to the control, while cisplatin increased the anti-apoptotic Bclx gene by 31.8 times and the treatment resistance AKT1 gene by 430.8 times the control. However, cisplatin only activated the extrinsic pathway of apoptosis through the caspase-3 gene. The expression levels of TLR6 and TNF-α genes in normal cells showed that both the gold(III) Schiff base complex and cisplatin did not cause inflammation in NIH 3T3 cell lines. All the results indicate that the new complex could be a promising candidate to replace cisplatin. It has been shown that it induces apoptosis and prevents the development of resistance in cancer cells. Additionally, it does not cause inflammation in normal cells.