Mhyre Andrew J, Marcondes A Mario, Spaulding Emily Y, Deeg H Joachim
Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA.
Blood. 2009 Jan 15;113(3):649-58. doi: 10.1182/blood-2008-04-152686. Epub 2008 Oct 22.
The role of the marrow microenvironment in the pathophysiology of myelodysplastic syndromes (MDSs) remains controversial. Using stromal/hematopoietic cell cocultures, we investigated the effects of stroma-derived signals on apoptosis sensitivity in hematopoietic precursors. The leukemia-derived cell line KG1a is resistant to proapoptotic ligands. However, when cocultured with the human stromal cell line HS5 (derived from normal marrow) and exposed to tumor necrosis factor-alpha (TNF-alpha), KG1a cells showed caspase-3 activation and induction of apoptosis. Apoptosis was contact dependent. Identical results were obtained in coculture with primary stroma. Gene-expression profiling of KG1a cells identified coculture-induced up-regulation of various genes involved in apoptosis, including PYCARD. Suppression of PYCARD expression in KG1a by miRNA interfered with apoptosis. Knockdown of the TNF receptor 1 (TNFR1) or TNFR2 in HS5 cells had no effect. However, knockdown of R1 in KG1a cells prevented TNF-alpha-induced apoptosis, while apoptosis was still induced by TNF-alpha-related apoptosis-inducing ligand. Primary CD34(+) cells from MDS marrow, when cocultured with HS5 and TNF-alpha, also underwent apoptosis. In contrast, no apoptosis was observed in CD34(+) cells from the marrow of healthy donors. These data indicate that stroma may convey not only protective effects on hematopoietic cells, but, dependent upon the milieu, may also facilitate apoptosis.
骨髓微环境在骨髓增生异常综合征（MDS）病理生理学中的作用仍存在争议。我们利用基质/造血细胞共培养体系，研究了基质衍生信号对造血前体细胞凋亡敏感性的影响。白血病衍生细胞系KG1a对促凋亡配体具有抗性。然而，当与人类基质细胞系HS5（源自正常骨髓）共培养并暴露于肿瘤坏死因子-α（TNF-α）时，KG1a细胞显示出半胱天冬酶-3激活并诱导凋亡。凋亡是接触依赖性的。与原代基质共培养也得到了相同的结果。KG1a细胞的基因表达谱分析确定了共培养诱导的多种参与凋亡的基因上调，包括PYCARD。通过miRNA抑制KG1a中PYCARD的表达会干扰凋亡。在HS5细胞中敲低肿瘤坏死因子受体1（TNFR1）或TNFR2没有效果。然而，在KG1a细胞中敲低R1可阻止TNF-α诱导的凋亡，而TNF-α相关凋亡诱导配体仍可诱导凋亡。来自MDS骨髓的原代CD34(+)细胞与HS5和TNF-α共培养时也会发生凋亡。相比之下，在健康供体骨髓的CD34(+)细胞中未观察到凋亡。这些数据表明，基质不仅可能对造血细胞具有保护作用，而且根据环境不同，也可能促进凋亡。
