Chiral Subunit-Modified Polyamide Mediating Apoptosis Of Oncogene C-Kit-Overexpressed Tumor Cells

Tumor is one of the major diseases that seriously threaten human health. The5-year survival rate with cancer patients is still low although the conventional surgery, radiotherapy and chemotherapy have made certain progress. So, in recent years targeted therapy has become a new research topic in tumor treatment. However as some multi-targeted therapy works effectively with strong side effects, it is necessary for development of single-targeted anti-tumor drugs with low cytotoxicity and high efficiency. Oncogene c-kit, highly expressed in some tumor cells, has a close relationship with tumor and is a better target for anticancer treatment. Polyamides are regarded as the molecules with the strongest specific recognition ability to DNA sequence in minor groove by a1:1binding mode, which gives such a great possibility to develop them as gene-targeted drugs.In this thesis, based on our previous research, five c-kit-targeted chiral recognition subunit-modified polyamides were designed and their ability to inhibit several kinds of cancer cells by regulation of c-kit has been explored. Firstly, four kinds of c-kit gene highly expressed tumor cells were screened as target cells by RT-PCR technology. Secondly, by using native-PAGE method the interaction between polyamides and the DNA sequence in c-kit key promoter region has been examined at moleculer level in vitro. The results revealed that polyamide4and polyamide5could bind to targeted DNA separately and polyamide5employs stronger affinity. Finally, RTCA system was used to monitor cell growth in a real-time manner at cell level. It was found that80μM polyamide4and20μM polyamide5both can strongly inhibit the growth of BEL7402cells and MKN45cells. Moreover, naphthalimides, another class of potential anti-tumor molecules synthesized in our laboratory, were also used to study cells toxicity by RTCA system. With A549cells and SGC7901cells,1μM polyamide5and20μM naphthalimides separately showed week inhibition to cells growth, but the cytotoxicity were quite enhanced when a combination of1μM polyamide5with20μM naphthalimides or0.lμg/mL anti-c-kit mAb was used. A combination of polyamide5with naphthalimide2showed stronger cytotoxicity to A549cells, while polyamide5combined with anti-c-kit mAb inhibited the growth of SGC7901cells more intensely. These data are of important value for exploration of gene-targeted drugs of anti-tumors with low cytotoxicity and high efficiency and tumor individualized therapy.