钌配合物稳定端粒DNA的作用及其诱导细胞凋亡分子机制的研究

Stabilization of Telomere DNA, and Mechanism of Apoptosis of Tumor Cells Induced by Ruthenium Complexes

端粒酶在肿瘤细胞中高表达,已经成为抗肿瘤药物的重要靶点,由于很多肿瘤细胞中富含G4-DNA,通过稳定G-四链体DNA的形成来抑制端粒酶的活性已成为抗癌药物的一个新策略.本文设计了两种钌配合物,调查了这两种钌配合物稳定G4-DNA的能力,发现配合物2稳定端粒G4-DNA的能力强于配合物1,配合物2能够诱导端粒G4-DNA发生构型的转化,而配合物1不能诱导G4-DNA发生构型的转化,这项研究结果证明,钌配合物与G4-DNA的作用能力与配体的平面性有关.在抗肿瘤活性方面,配合物2表现出更强的抗肿瘤活性,尤其是对HepG2细胞具有较强的抑制作用,推测其是以端粒酶为靶点发挥的抗肿瘤作用.配合物2能够诱导肿瘤细胞凋亡,能诱导G1期细胞阻滞和DNA碎片的形成(细胞凋亡的特征).据此推测本论文设计的钌配合物是一个潜在的抗肿瘤药物.

Telomerase is highly expressed in tumor cells, which has become an important target of anticancer drugs. Since many tumor cells were rich in G4-DNA, we investigated the capabilities of these two ruthenium complexes to stabilize G4-DNA. Two ruthenium(II) complexes were synthesized and characterized via electrospray ionization-mass spectrometry. Since many tumor cells were rich in G4-DNA, we investigated the capabilities of these two ruthenium complexes to stabilize G4-DNA. The interactions of these compounds with G-quadruplex DNA have been studied by fluorescence spectroscopy and circular dichroism(CD) spectroscopy. The stabilization of quadruplex DNA to complex 2 was better than complex 1, and complex 2 can induce telomeric G-quadruplex to occur conformation transformation, while complex 1 cannot. The results showed that the interaction of ruthenium complexes with G-quadruplex DNA was related with the plane of ligand. A novel visual method has been developed for making a distinction between ct-DNA and HTG21 by our Ru complexes binding hemin to form the hemin-G-quadruplex DNAzyme. The results showed that in the presence of complex 1 or 2, HTG21 can fold into a G-quadruplex, but CT-DNA cannot form the G-quadruplex structure. The anticancer activities of these complexes were evaluated by using the MTT assay. Interestingly, the anti-tumor activity of complex 2 exhibited greater inhibition to HepG2 cells, suggesting the ruthenium complexes were much less toxic towards normal cells, and speculated that it targeted the telomeric G-quadruplex was play a role on anti-tumor effect. To further evaluate the characteristics of the death induced by complexes 1 and 2-treated cells staining with Hoechst is analyzed by fluorescence microscopy. These results indicated that complex 2 revealed antiproliferative activities by apoptosis. We also used PI staining and flow cytometry to assess whether the ruthenium complex 2 affected cell cycle progression in HepG2 cells. Complex 2 is a potential antitumor drugs that can induce cancer cell death by acting on cell cycle arrest in G1 phase and the formation of DNA fragments(apoptosis characteristics).