GAS2调控慢性粒细胞白血病干细胞生长的研究

生长抑制特异蛋白GAS2可通过calpain/beta-catenin途径维持肿瘤细胞生长。我们发现慢性粒细胞白血病（CML）的干、祖细胞中GAS2较正常对照细胞表达显著增高；CML细胞株和原代CD34+细胞的生长需要GAS2；靶向GAS2导致的细胞生长减缓依赖calpain的活化但无需beta-catenin。然而，Gas2能否与BCR-ABL协同恶性转化正常干细胞、GAS2能否维持CML干细胞的生长和GAS2/calpain的关键下游分子是什么等核心问题尚未得到阐述。本项目将在上述预研基础上研究Gas2对BCR-ABL恶性转化能力的影响；检测干扰CML干细胞中GAS2表达对其长期培养起始细胞（LTC-IC）和小鼠移植能力的影响；使用蛋白质组策略揭示GAS2的作用机制。本项目的完成将首次阐述GAS2在CML干细胞中的功能和机制、完善对CML致病分子机制的认知，为改善CML治疗提供新策略。

Growth arrest specific 2 (GAS2) could regulate calpain/beta-catenin pathway to maintain the growth of tumour cells including the BCR-ABL expressed murine bone marrow progenitor cells. We found that GAS2 was up-regulated in the CD34+ and CD34+CD38-Ph+ cells from the chronic myeloid leukemia (CML) patients compared to their normal counterparts. Targeting GAS2 with either RNAi or expression of the dominant negative form of GAS2 (GAS2DN) was capable to inhibit the growth of K562, MEG-01 and CD34+ cells from patients, which was partially dependent on the activation of calpain. Unexpectedly, we found that targeting GAS2 could inhibit CML cells through a beta-catenin independent signaling. However, the role of GAS2 and its underlying mechanism in the maintanence and initiation of leukemic stem cells has not been addressed. We propose to study the LTC-IC (long term culture-initiating cell) and xenoengraftment capacityies of CD34+CD38-IL1RAP+ cells from CML patients, when GAS2 in these cells was suppressed. In the other hand, we will deliver Gas2 alone or together with BCR-ABL into the lin-Sca-1+c-Kit+ cells from mice bone marrow to study the effect of these factors on hematopoiesis and the leukemogenesis. Mechanistically, we will utilize proteomic approach to identify key factors regulated by GAS2 to control the growth of CML primitive cells. We believe that the delineation of the role of GAS2 in CML stem cells will obtain novel molecular insights of these cells and provide opportunities to pursue novel therapies.