Cytotoxicity, molecular modeling, cell cycle arrest, and apoptotic induction induced by novel tetrahydro-[1,2,4]triazolo[3,4-a]isoquinoline chalcones

Abstract

Novel tetrahydro-[1,2,4]triazolo[3,4-a]isoquinolin-3-yl)-3-arylprop-2-en-1-one derivatives were synthesized and their structures were confirmed by different spectral tools. Cytotoxicity test revealed that some compounds exhibited strong to moderate effect, while others showed weak action against different cancer cell lines (MCF7, A549, HCT116, and Hepg2). Breast carcinoma revealed higher sensitivity toward all derivatives especially compounds 5 and 8 which offered the lowest IC₅₀ values (50.05, and 27.15 μg/ml) respectively, relative to the positive control 5-fluorouracil (5-FU) (IC₅₀ = 178 μg/ml). In addition, the two compounds exhibited less toxic effect toward normal melanocytes (HFB4). Several theoretical and experimental studies were done to reveal the molecular mechanisms that control breast carcinoma metastasis using the two promising novels 5 and 8. Docking simulation studies against the two proteins EGFR and DHFR demonstrate that compound 8 showed higher binding affinity toward the two proteins more than compound 5, suggesting that trimethoxy groups may be responsible for this higher activity through the formation of five hydrogen bonding with the active domain (4r3r) and other four interactions with the active domain (1dls). Real time PCR assay illustrates that the two compounds up regulated BAX, p53, caspase-3 genes and down regulated BCL2, MMP1, CDK4 ones. In addition, it was noted that compound 8 was more effective in gene regulation and apoptotic induction than compound 5. Also, flow cytometer analysis demonstrates that both compounds 5 and 8 induced cell growth arrest at G1 phase and thus, inhibit G1/S transition and cell cycle progression. In addition, both compounds stimulate apoptotic death of breast cells significantly to reach 8.72%, and 17.28% respectively, compared to their control (0.55%). Apoptotic induction of breast cells was enhanced effectively through activation of caspase-3 by compound 8 using Elisa assay.

Keywords: Apoptosis; Breast cancer; Caspase-3; Cell cycle arrest; Chalcones; Modeling study; Tetrahydro-[1,2,4]triazolo[3,4-a]isoquinoline; p53.