二甲双胍靶向AMPK/mTOR（mTORC1和mTORC2）通路抗骨髓瘤的机制研究

Multiple myeloma(MM) is an hematologic malignancy and remains incurable.It is characterized by constitutive activation of PI3K/Akt/mTOR pathway.As mTOR complex 1 (mTORC1)inhibitors,rapamycin and its analogs suggest potential in treatment of MM,but they have shown limited efficacy in clinic,largly because of the feekback of Akt activation.Our team member reported,metformin can inhibit the growth of lymphoma cell lines via AMPK/mTOR pathway.Interestingly,not like mTORC1 inhibitor,it didn't activate Akt.We suspect that metformin could prevent actvivation of mTORC1 and mTORC2 simultaneously.It could also inhibit phosphorylation of Akt,a mTORC2 substrate.Lately we treat myeloma cell line H929 with metformin.We find it can inhibit the growth of myeloma cells with lower concentration.On base of these finding, we will further study on the effection of metformin on proliferation of the myeloma cell lines and its mechanism, especially on the AMPK/mTOR(mTORC1&mTORC2)signaling pathway.We will also do some study with patients' primary MM cell and mice model.We hope our study will provide the theoretical basis for the treatment of MM by using this traditional safety and efficiency drug.

多发性骨髓瘤是血液系统的恶性肿瘤，至今仍无法治愈。研究表明PI3K/Akt/mTOR通路在骨髓瘤中处于持续活化状态。单纯mTOR抑制剂雷帕霉素及其类似物主要靶向mTORC1，虽有一定的抗骨髓瘤作用，但会引起反馈性Akt激活，影响疗效。申请人所在课题组已证实二甲双胍可通过激活AMPK，下调mTOR，抑制淋巴瘤细胞生长,更重要的是不会反馈性激活Akt。我们推测这与它同时抑制mTORC1和mTORC2，及mTORC2下游的Akt有关。最近在对骨髓瘤的研究中，我们发现二甲双胍能以更低的药物浓度抑制H929细胞增殖。本课题拟在前期工作的基础上，进一步研究二甲双胍抑制骨髓瘤细胞生长的分子信号网络，特别是它对AMPK/mTOR(mTORC1和mTORC2)通路及其下游分子的影响。并利用原代细胞和小鼠模型探求二甲双胍治疗骨髓瘤的临床潜力,为这一临床已长期使用的安全有效的药物运用于骨髓瘤的治疗提供理论依据。

二甲双胍是治疗糖尿病的传统老药，近年来被反复证实具有抗肿瘤作用。我们的课题组，将二甲双胍作用于骨髓瘤细胞株RPMI8226、H929和U266细胞，发现可有效抑制细胞的增殖。在原代细胞（患者骨髓瘤细胞）中也证实了二甲双胍的增殖抑制作用，而对人正常干细胞并无抑制作用。体外实验发现二甲双胍是通过诱导MM细胞自噬和G0/G1期阻滞，来抑制肿瘤细胞生长的。通过对分子信号通路的进一步研究发现，二甲双胍通过激活AMPK，抑制mTORC1/raptor/ULK1诱导自噬，通过抑制mTORC2/AKT/FOXO1来抑制细胞周期。小鼠动物实验同样证实了我们的研究，治疗组小鼠肿瘤生长明显比对照组缓慢，病理组化也证实了KI-67增殖活性的下降，AMPK的上调，AKT的抑制。二甲双胍通过其独特的双向抑制mTORC1和mTORC2的作用，有效的抑制了骨髓瘤细胞的生长，是极具临床潜力的药物。我们的研究为二甲双胍这一安全价廉的老药用于骨髓瘤的治疗提供了坚实理论依据。