Apoptosis In Tumor Cells Induced By Novel Naphthalimide-thiourea Compounds

Naphthalimides are significant examples of DNA-intercalating agents,many of which, such as Amonafide and Mitonafide,have been used in PhaseⅡclinical trials.But there are still many problems with them which had high neurotoxicity and poor tumor selectivity, efficiency and safety.dNIT and sNIT series Naphthalimide-thiourea Compounds were designed and synthesized by Stata Key Laboratory of Fine Chemicals,Dalian University of Technology.The thiourea motifs was used to elevate affinity with DNA.In this study,We investigated the cytotoxicity of dNITs and sNITs in Hela cells model,U251 cells model,SMMC-7721 cells model and MCF-7 cells model by MTT assay.The results showed that bisnaphthalimides had more interactions with DNA than the naphthalimides,and the cytotoxicity and tumor selectivity of dNITs were not dependent on the tether length.After treatment with 2.5-40μmol/L dNIT-6,the IC50 of MCF-7 cells were 9.93±1.03μmol/L(12h), 8.72±1.22μmol/L(18h) and 6.92±1.56μmol/L(24h).After treatment with 2.5-40μmol/L dNIT-2,the IC50 of SMMC-7721 cells were 12.76±1.19μmol/L(12h),10.16±1.31μmol/L (18h) and 7.75±1.43μmol/L(24h).So dNIT-2 and dNIT-6 were expected to the further studies.After MCF-7 cells were treated with dNIT-6 for 12h,the morphological changes of cells were observed under the mierophotography.Then the cell cycle,apoptosis of MCF-7 cells and the levels of P53 and Bcl-2 protein expression in MCF-7 cells were detected by flow cytometry(FCM).caspases activities were determined by absorption spectroscopy.Results showed that dNIT-6 exposure results in apoptotic cell death,increased the proportion of cells in G0/G1-phase,activated the P53 protein,decreased the level of Bcl-2 protein,and then increased the activities of caspase-9 and caspase-3,then triggered the cascade of apoptosis in MCF-7 cells.After SMMC-7721 cells were treated with dNIT-2 for 12h,the morphological changes of cells were observed under the microphotography.Then the cell cycle,apoptosis of MCF-7 cells and the levels of P53 and Bcl-2 protein expression in MCF-7 cells were detected by FCM.Mitochondrial membrane depolarization was assayed by Rh123.caspases activities were determined by absorption spectroscopy.Results showed that dNIT-2 exposure results in apoptotic cell death,increased the proportion of cells in S-phase,activated the P53 protein, decreased the mitochondrial membrane potential and the level of Bcl-2 protein,increased the activities of caspase-9 and caspase-3,then triggered the cascade of apoptosis in MCF-7 cells.In conclusion,we evaluated the cytotoxicity of the dNITs and the sNITs.Altogether our findings demonstrated dNIT-6 and dNIT-2 could induce apoptosis in MCF-7 cell and SMMC-7721 cell by activating P53 protein and inhibiting the Bcl-2 in a dose-dependent manner.But the mechanisms in MCF-7 and SMMC-7721 are different which may be relevant to the difference of the tumor cells.Data from this study was not only useful for the further utilization in cancer treatment,but also prvided a novel insight into the design and synthesis of antitumor compounds.