Zaninoni Anna, Imperiali Francesca Guia, Pasquini Cristina, Zanella Alberto, Barcellini Wilma
Dipartimento di Ematologia, IRCCS Ospedale Maggiore di Milano, Milan, Italy.
Exp Hematol. 2003 Mar;31(3):185-90. doi: 10.1016/s0301-472x(02)01046-9.
Dysregulation of the apoptotic mechanisms plays a key role in the accumulation of malignant B-chronic lymphocytic leukemia (B-CLL) cells. The transcription nuclear factor (NF)-kappaB is important for cell survival by regulating the expression of anti-apoptotic genes. Several cytokines can modulate leukemic growth and apoptosis in B-CLL. The aim of this study was to determine whether cytokine-mediated regulation of apoptosis occurs via modulation of NF-kappaB activity in peripheral blood mononuclear cells from B-CLL patients.
We evaluated NF-kappaB activity in peripheral blood mononuclear cells from 15 untreated B-CLL patients and 11 controls in resting conditions and in the presence of phorbol-12-myristate-13-acetate (PMA) and different cytokines by electrophoretic mobility shift assay. Apoptosis was studied by spectrophotometric analysis of DNA fragmentation.
We found a constitutive high NF-kappaB activity not induced by PMA in B-CLL patients, in contrast with a normal inducible NF-kappaB activity in controls. In B-CLL cultures, addition of interleukin (IL)-4 and IL-13 increased, whereas transforming growth factor (TGF)-beta reduced NF-kappaB activity compared with unstimulated cultures. Accordingly, IL-4 and IL-13 decreased, whereas TGF-beta increased DNA fragmentation compared with unstimulated cultures. IL-13 and IL-4 production was increased, whereas TGF-beta was reduced in PMA-stimulated and unstimulated cultures from B-CLL patients compared with controls.
B-CLL patients have a constitutive high NF-kappaB activity, which is modulated by cytokines. In particular, TGF-beta displays a pro-apoptotic activity, whereas IL-4 and IL-13 have opposite effects. These cytokine alterations could be responsible for a positive autocrine circuit that maintains leukemic cells in a pre-apoptotic state.
凋亡机制失调在恶性B细胞慢性淋巴细胞白血病（B-CLL）细胞的积累中起关键作用。转录核因子（NF）-κB通过调节抗凋亡基因的表达对细胞存活至关重要。几种细胞因子可调节B-CLL中的白血病细胞生长和凋亡。本研究的目的是确定细胞因子介导的凋亡调节是否通过调节B-CLL患者外周血单个核细胞中的NF-κB活性而发生。
我们通过电泳迁移率变动分析评估了15例未经治疗的B-CLL患者和11例对照在静息状态下以及在存在佛波醇-12-肉豆蔻酸酯-13-乙酸酯（PMA）和不同细胞因子的情况下外周血单个核细胞中的NF-κB活性。通过DNA片段化的分光光度分析研究凋亡。
我们发现B-CLL患者中存在组成性高NF-κB活性，不受PMA诱导，而对照组中NF-κB活性正常且可诱导。在B-CLL培养物中，与未刺激的培养物相比，添加白细胞介素（IL）-4和IL-13可增加NF-κB活性，而转化生长因子（TGF）-β可降低NF-κB活性。相应地，与未刺激的培养物相比，IL-4和IL-13可减少DNA片段化，而TGF-β可增加DNA片段化。与对照组相比，B-CLL患者的PMA刺激和未刺激培养物中IL-13和IL-4的产生增加，而TGF-β减少。
B-CLL患者具有组成性高NF-κB活性，该活性受细胞因子调节。特别是，TGF-β具有促凋亡活性，而IL-4和IL-13具有相反的作用。这些细胞因子改变可能导致正自分泌回路，使白血病细胞维持在凋亡前状态。
