Konopleva M, Konoplev S, Hu W, Zaritskey A Y, Afanasiev B V, Andreeff M
Section of Molecular Hematology and Therapy, Department of Blood and Marrow Transplantation, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Leukemia. 2002 Sep;16(9):1713-24. doi: 10.1038/sj.leu.2402608.
The aim of this study was to study interactions between stromal bone marrow microenvironment and leukemic cells. We tested the hypothesis that stromal cells prevent apoptosis of AML cells by up-regulating anti-apoptotic proteins in leukemic blasts. In HL-60 and NB-4 cells, serum deprivation- and ara-C-induced apoptosis was diminished when cells were cocultured with murine MS-5 stromal cells (P < 0.02). This effect was reproduced with conditioned medium from MS-5 cells. Cocultivation with stromal cells induced Bcl-2 expression levels, both by PCR analysis and flow cytometry. In primary AML (n = 14), ara-C-induced apoptosis was significantly lower in cells cocultured with MS-5 cells than in controls (P < 0.001). This effect was partially preserved when leukemic cells were separated from stromal cells by a microporous insert (in 5/9 samples, P = 0.04). In addition, Bcl-2 levels were significantly higher in stroma-supported than in control CD34(+) AML cells (P < 0.01). Bcl-X(L) levels were higher in 5/7 samples grown on stromal layers. Of note, in AML patients resistant to induction chemotherapy (n = 6), Bcl-2 increased significantly after cultivation with stromal cells, but no such increase was noted in cells from chemotherapy-sensitive patients. In conclusion, MS-5 stromal cells prevented apoptosis in HL-60 cells and in primary AML blasts via modulation of Bcl-2 family proteins. The observed association of high Bcl-2 expression in stroma-supported AML blasts in vitro with resistance to chemotherapy in vivo suggests that the same mechanisms may be operational in vivo.
本研究的目的是探讨基质骨髓微环境与白血病细胞之间的相互作用。我们检验了这样一个假设，即基质细胞通过上调白血病母细胞中的抗凋亡蛋白来阻止急性髓系白血病（AML）细胞的凋亡。在HL-60和NB-4细胞中，当与小鼠MS-5基质细胞共培养时，血清剥夺和阿糖胞苷（ara-C）诱导的凋亡减少（P < 0.02）。MS-5细胞的条件培养基也产生了同样的效果。通过PCR分析和流式细胞术检测，与基质细胞共培养可诱导Bcl-2表达水平升高。在原发性AML（n = 14）中，与MS-5细胞共培养的细胞中，ara-C诱导的凋亡明显低于对照组（P < 0.001）。当白血病细胞通过微孔插入物与基质细胞分离时，这种效应部分得以保留（5/9个样本，P = 0.04）。此外，基质支持的CD34(+) AML细胞中的Bcl-2水平明显高于对照组（P < 0.01）。在基质层上生长的5/7个样本中，Bcl-X(L)水平较高。值得注意的是，在对诱导化疗耐药的AML患者（n = 6）中，与基质细胞共培养后Bcl-2显著增加，但在化疗敏感患者的细胞中未观察到这种增加。总之，MS-5基质细胞通过调节Bcl-2家族蛋白阻止了HL-60细胞和原发性AML母细胞的凋亡。体外观察到基质支持的AML母细胞中高Bcl-2表达与体内化疗耐药之间的关联表明，相同的机制可能在体内起作用。
