Adem Jemal, Ropponen Antti, Eeva Jonna, Eray Mine, Nuutinen Ulla, Pelkonen Jukka
*Department of Clinical Microbiology, Institute of Clinical Medicine †Cancer Center, University of Eastern Finland ∥Eastern Finland Laboratory Centre (ISLAB), Kuopio ‡Fimlab LaboratoriesOy, Tampere University Hospital §Department of Medicine, University of Tampere, Tampere, Finland.
J Immunother. 2016 Jan;39(1):8-14. doi: 10.1097/CJI.0000000000000102.
Bcl-2 family comprises proapoptotic and antiapoptotic proteins. The balance between these proteins is critical for the survival of the cells. Overexpression of the antiapoptotic protein, Bcl-2, is the hallmark of follicular lymphoma (FL). High expression of Bcl-2 provides survival advantage and may facilitate chemotherapeutic resistance in FL. In the present study, we examined expression profile of Bcl-2 family proteins such as Bcl-2, Bcl-xL, and Bim in human FL cell lines, HF1A3 and HF28. We assessed the correlation between the expression levels of these proteins and cells' sensitivity to dexamethasone (Dex)-mediated and B-cell receptor (BCR)-mediated apoptosis. Here, we show that Dex and anti-BCR-induced synergistic apoptosis which correlated with significant downregulation of Bcl-xL, inhibition of ERK1/2 phosphorylation and accumulation of nonphosphorylated Bim. However, HF28 cells were less sensitive than HF1A3 cells to Dex-induced and anti-BCR-induced apoptosis due to high Bcl-2 protein level. It is interesting to note that, a Bcl-2-specific inhibitor, ABT-199, sensitized HF28 cells to Dex-induced or anti-BCR-induced apoptosis. In addition, overexpression of Bcl-xL prevented Dex-mediated, anti-BCR-mediated, and ABT-199-mediated apoptosis, indicating that mitochondria were involved. In conclusion, these data show that the expression levels of Bcl-2 family proteins may serve to predict tumor response to BH3 mimetics and the sensitivity of FL cells to Dex-induced and anti-BCR-induced apoptosis. Moreover, our results show that BCR-targeted apoptosis might have therapeutic benefit against FL and B-cell lymphomas.
Bcl-2家族由促凋亡蛋白和抗凋亡蛋白组成。这些蛋白之间的平衡对于细胞的存活至关重要。抗凋亡蛋白Bcl-2的过表达是滤泡性淋巴瘤(FL)的标志。Bcl-2的高表达赋予生存优势,并可能促进FL中的化疗耐药性。在本研究中,我们检测了人FL细胞系HF1A3和HF28中Bcl-2家族蛋白如Bcl-2、Bcl-xL和Bim的表达谱。我们评估了这些蛋白的表达水平与细胞对地塞米松(Dex)介导的和B细胞受体(BCR)介导的凋亡的敏感性之间的相关性。在此,我们表明Dex和抗BCR诱导协同凋亡,这与Bcl-xL的显著下调、ERK1/2磷酸化的抑制以及非磷酸化Bim的积累相关。然而,由于Bcl-2蛋白水平高,HF28细胞比HF1A3细胞对Dex诱导的和抗BCR诱导的凋亡更不敏感。值得注意的是,一种Bcl-2特异性抑制剂ABT-199使HF28细胞对Dex诱导的或抗BCR诱导的凋亡敏感化。此外,Bcl-xL的过表达阻止了Dex介导的、抗BCR介导的和ABT-199介导的凋亡,表明线粒体参与其中。总之,这些数据表明Bcl-2家族蛋白的表达水平可能有助于预测肿瘤对BH3模拟物的反应以及FL细胞对Dex诱导的和抗BCR诱导的凋亡的敏感性。此外,我们的结果表明靶向BCR的凋亡可能对FL和B细胞淋巴瘤具有治疗益处。