Increase delivery, cytotoxicity, stability and induction of apoptosis in cisplatin by establishing a new complex with methotrexate

Abstract

Cisplatin, as an effective anti-cancer drug, is widely used to treat breast cancer. However, undesirable side effects and drug resistance have partially limited its use for some patients. One of the causes of side effects is the lack of differentiation between cancer cells and normal cells, which could be reduced by targeted drug delivery. Therefore, we decided to replace methotrexate, as a targeting ligand, with chlorine atoms of cisplatin and evaluate its effect on cytotoxicity and induction of apoptosis in T47D (invasive ductal carcinoma) cell lines. FTIR and 13C NMR methods proved the coordination of methotrexate to cisplatin and the formation of the eight-membered ring between them. The results of the MTT assay showed that the cis-[Pt(NH3)2MTX] complex showed a time- and dose-dependent cytotoxic effect at both periods of 48 and 72 h. Although the IC50 of the new complex was higher when compared to cisplatin (78 vs. 33 μM), it completely inhibited the cell viability of the T47D cells after 72 h of exposure. The results of the real-time PCR test approved that the cis-[Pt(NH3)2MTX] complex can induce the intrinsic apoptosis pathway by increasing the level of Bak1 proteins, while cisplatin does not affect any of the studied genes. Molecular docking confirmed that four amino acids of folate receptors such as ASP 81, SER 174, SER 101, and TRP 138 were involved in binding to the cis-[Pt(NH3)2MTX] complex. Finally, the atoms-in-molecules method and molecular electrostatic potential confirmed that the new complex has more stability than cisplatin via the coexistence of the Intra-HB and Inter-HB interactions.