REGULATION OF NORMAL AND NEOPLASTIC HEMATOPOIETIC CELL GROWTH--ROLE OF BRMS

该项目的目标是更好地了解细胞外和 细胞内正、负调节因子之间的相互作用 造血干细胞（SC），因为它们涉及的机制（S） 恶性转化和发展治疗上有用的 基因治疗方案 启动和维持增长， 原始祖细胞分化，多种细胞因子 需要刺激。 这导致了“增长因素”的概念 协同作用”。 我们表明，这种协同性也发生在负之间 造血细胞生长的调节因子， 造血祖细胞的增殖依赖于细胞内正、负 细胞接收的信号。 几种抑制性细胞因子中， TGF-β直接和可逆地抑制所有造血SC 具有骨髓再生能力的人群。 TGF-β具有抑制 影响许多细胞因子受体的细胞表面表达， 与其对细胞生长的影响直接相关。 SC因子受体 TGF-β部分通过影响c-kit表达下调， 试剂盒mRNA稳定性。 此外，TGF-β阻止S期细胞周期 通过涉及c-调节的细胞内机制的进展 myb以及c-myc。 体内结果表明，TGF-β可以 保护小鼠免受5-FU的致死性造血毒性，以及 DXR的非造血毒性。 调查结果显示， 造血负调节剂可成功地全身使用 来介导体内的化学保护。 几种正调控因子 在体内使用造血细胞以确定它们对 骨髓生成 rhIL-7每日2次，连续7天 不会明显改变BM细胞结构，但确实导致3倍于 5-脾脏中白细胞总数增加一倍， 外周血白细胞总数增加20倍。 使用我们 调节血液细胞生长的能力，我们确定了 在这种条件下，基因转移的可行性。 我们确定， HS-tk自杀基因的离体转移到T细胞中， 输注造血干细胞可允许选择性体内耗竭 这些T细胞与更昔洛韦（GCV），如果需要随后出现。

The goal of this project is to better understand the extracellular and intracellular interactions between positive and negative regulators of hematopoietic stem cells (SC) as they pertain to the mechanism(s) of malignant transformation and to the development of therapeutically useful gen therapy protocols. To initiate and maintain the growth and differentiation of primitive progenitor cells, multiple cytokine stimulation is required. This has led to the concept of "growth facto synergy". We show that such cooperativity also occurs between negative regulators of hematopoietic cell growth, and that the ability of primitive progenitors to proliferate depends on the balance of positive and negative signals the cell receives. Of several inhibitory cytokines studied only TGF-beta directly and reversibly inhibited all hematopoietic SC populations with marrow repopulating ability. TGF-B has inhibitory effects on the cell surface expression of many cytokine receptors that directly correlates with its effect on cell growth. SC factor receptor (c-kit) expression is down-regulated by TGF-beta in part by affecting c- kit mRNA stability. Also, TGF-beta prevents S phase cell cycle progression through an intracellular mechanism involving regulation of c- myb as well as c-myc. In vivo results demonstrated that TGF-beta can protect mice from both the lethal hematopoietic toxicity of 5-FU, as well as the non-hematopoiesis toxicity of DXR. The findings show that a negative regulator of hematopoiesis can be successfully used systemically to mediate chemoprotection in vivo. Several positive regulators of hematopoietic cells were used in vivo to determine their effect on myelopoiesis. The administration of rhIL-7 to mice twice a da for 7 days does not appreciably change BM cellularity, but does result in a 3-fold to 5-fold increase in the total number of leukocytes in the spleen and up to a 20-fold increase in the total number of peripheral WBC. Using our ability to regulate the growth of hematologic cells, we determined the feasibility of gene transfer under these conditions. We established that the ex-vivo transfer of the HS-tk suicide gene into T-cells before their infusion with hematopoietic SC could allow for selective in vivo depletion of these T-cells with ganciclovir (GCV) if the need subsequently arises.