高选择性SIRT6变构抑制剂的设计、合成及抗肿瘤功能研究

SIRT6 has been implicated in multiple biological phenomenons and associated with the genesis and development of tumors. The complex regulation mechanisms of the dual role of SIRT6 in tumor suppression or carcinogenesis need further study. In order to reveal the functional mechanisms of SIRT6 in tumors better, it is urgent to find its highly potent and selective inhibitors. However, it is difficult for the competitive inhibitors to achieve high selectivity for SIRT6 because the active site possesses high conservatism, while allosteric modulators could overcome this problems for the non-conservative allosteric sites between subtype members. We have discovered allosteric inhibitors of SIRT6 for the first time by our self-developed allosteric drug design methods, which have high selectivity for SIRTs and HDACs. It can inhibit the proliferation of leukemia cells and lymphoma cells in vitro to a certain degree, while the mechanisms have not yet been elucidated. Thus, this project intends to obtain selective SIRT6 inhibitors with high potential and illuminate their interaction mechanism as well as explore the antitumor mechanisms of SIRT6. We aimed to provide new evidence for SIRT6 as a promising antitumor drug target and contribute to innovative drug development based on the lead compound.

SIRT6参与调控诸多生命现象，与肿瘤发生发展密切相关，起到抑癌或致癌的双重作用，其复杂的调控机制尚需深入研究。为了更好的揭示其功能机制，亟需发现SIRT6高效、高选择性抑制剂。但由于SIRT6活性中心具有高度保守性，底物竞争性抑制剂难以实现SIRT6高选择性，而变构调节剂由于靶向于不保守的变构位点，适于对蛋白家族亚型成员进行区分，有望解决SIRT6高选择性抑制的难题。我们通过自主发展的变构药物设计方法，首次发现了SIRT6变构抑制剂，具有较高的SIRTs及HDACs的选择性，体外实验显示其对白血病细胞、淋巴瘤细胞增殖具有一定的抑制活性，其作用机制尚未阐明。基于此，本项目拟：进一步提高SIRT6抑制剂的活性及选择性；阐明抑制剂与SIRT6相互作用模式；探索SIRT6抑制肿瘤的功能机制。以期为SIRT6作为抗肿瘤靶标的研究提供新依据，同时也为开发创新药物奠定先导化合物基础。

SIRT6是NAD+依赖的组蛋白去乙酰化酶HDAC家族成员之一，涉及多种生理及病理过程。但由于SIRT6的正构位点在Sirtuins家族中高度保守，开发具有特异性SIRT6分子探针具有极大挑战，严重阻碍了研究SIRT6的功能机制。生物大分子上天然存在着一类不易发现的变构位点（allosteric site），其保守性相对较差，被结合后可诱导构象变化实现对蛋白功能选择性调节。基于大分子的底物位点与变构位点存在着双向通讯现象，本项目发展了以底物位点配体分子为天然探针来识别隐式变构位点（cryptic/hidden allosteric site）的新方法AlloReverse。利用这一方法，在SIRT6上发现了一个全新隐式变构位点Pocket Z，结合虚拟筛选和结构优化改造，成功获得了高选择性变构抑制剂，阐明抑制剂对SIRT6变构抑制模式。进一步以变构抑制剂为分子探针，研究了抑制SIRT6去乙酰化功能在胰腺癌细胞迁移侵袭中的作用。