Clutter Suzanne D, Fortney James E, Gibson Laura F
Department of Microbiology and Immunology, Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV, USA.
Exp Hematol. 2006 Nov;34(11):1522-31. doi: 10.1016/j.exphem.2006.06.021.
Bone marrow stromal cell function is a critical influence on hematopoietic reconstitution following progenitor or stem cell transplantation. Stromal cells support hematopoietic cell migration, survival, and proliferation. We have previously reported that stromal cell matrix metalloproteinase-2 (MMP-2) is necessary for optimal support of pro-B-cell chemotaxis through its regulation of stromal cell-derived factor-1 (CXCL12) release. Following exposure to the topoisomerase II inhibitor, etoposide (VP-16), stromal cell MMP-2 protein expression is reduced. The current study investigated the mechanism by which VP-16 may alter translation of MMP-2 in bone marrow stromal cells.
Bone marrow stromal cells were exposed to chemotherapeutic agents etoposide, melphalan, and 4-hydroperoxycyclophosphamide (4HC) and evaluated for MMP-2 expression by enzyme-linked immunosorbent assay and support of pro-B-cell chemotaxis by chemotaxis assay. Western blot analyses were completed to evaluate phosphorylation of stromal cell translational regulatory proteins 4E binding protein-1 (4EBP-1), P70(S6K), and S6 or MMP-2 in the presence of chemotherapy, or the chemical inhibitors rapamycin or LY294002.
Rapid dephosphorylation of 4EBP-1, P70(S6K), and S6 following VP-16 exposure was observed, consistent with blunted translational efficiency. We also observed that inhibition of stromal cell mammalian target of rapamycin with rapamycin, or phosphatidylinositol 3 kinase with LY294002, resulted in inhibition of stromal cell MMP-2 protein. In addition we found that the chemotherapeutic agents melphalan and 4HC disrupt bone marrow stromal cell MMP-2 protein expression and support of chemotaxis.
These data suggest that one mechanism by which chemotherapy may alter stromal cells of the bone marrow microenvironment is through disrupted translation of proteins.
骨髓基质细胞功能对祖细胞或干细胞移植后的造血重建具有关键影响。基质细胞支持造血细胞迁移、存活和增殖。我们之前报道过，基质细胞基质金属蛋白酶-2（MMP-2）通过调节基质细胞衍生因子-1（CXCL12）的释放，对前B细胞趋化性的最佳支持是必需的。暴露于拓扑异构酶II抑制剂依托泊苷（VP-16）后，基质细胞MMP-2蛋白表达降低。本研究调查了VP-16可能改变骨髓基质细胞中MMP-2翻译的机制。
将骨髓基质细胞暴露于化疗药物依托泊苷、美法仑和4-氢过氧环磷酰胺（4HC），通过酶联免疫吸附测定评估MMP-2表达，并通过趋化性测定评估对前B细胞趋化性的支持。在存在化疗药物、化学抑制剂雷帕霉素或LY294002的情况下，完成蛋白质印迹分析以评估基质细胞翻译调节蛋白4E结合蛋白-1（4EBP-1）、P70（S6K）和S6或MMP-2的磷酸化。
观察到VP-16暴露后4EBP-1、P70（S6K）和S6迅速去磷酸化，这与翻译效率降低一致。我们还观察到，用雷帕霉素抑制基质细胞雷帕霉素哺乳动物靶点，或用LY294002抑制磷脂酰肌醇3激酶，会导致基质细胞MMP-2蛋白受到抑制。此外，我们发现化疗药物美法仑和4HC会破坏骨髓基质细胞MMP-2蛋白表达和趋化性支持。
这些数据表明，化疗可能改变骨髓微环境基质细胞的一种机制是通过破坏蛋白质翻译。
