Prohibitin (PHB) expression is associated with aggressiveness in DLBCL and flavagline-mediated inhibition of cytoplasmic PHB functions induces anti-tumor effects
Prohibitin (PHB) expression is associated with aggressiveness in DLBCL and flavagline-mediated inhibition of cytoplasmic PHB functions induces anti-tumor effects
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DOI：
10.1186/s13046-019-1440-4
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发表时间：
2019-11-04
影响因子：
11.3
通讯作者：
Troutaud, Danielle
中科院分区：
文献类型：
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作者：
Bentayeb, Hafidha;Aitamer, Marine;Troutaud, Danielle
弥漫性大B细胞淋巴瘤（DLBCL）是一种侵袭性淋巴瘤，约占非霍奇金淋巴瘤的三分之一。抑制素1（PHB 1）和抑制素2（PHB 2）是促进线粒体稳态并因此促进细胞存活的支架蛋白，但胞质PHBs的生物学功能在DLBCL中仍然很大程度上未知。方法采用免疫组化（IHC）和Western blotting检测82例DLBCL活检组织和5株DLBCL细胞系中PHB的表达。在体外实现了使用合成的黄曲霉素FL 3对PHB的药理学抑制，以了解PHB细胞功能。分别采用XTT法、Annexin V-FITC/PI双染法和Western blotting法检测FL 3对DLBCL细胞株存活率、细胞凋亡、C-Raf-ERK-MNK-eIF 4 E信号通路和eIF 4F复合物形成及活性的影响。还在SCID小鼠中进行皮下DLBCL异种移植物模型以确定体内FL 3作用。结果与DLBCL细胞株一样，PHB 1和PHB 2表达于生发中心B细胞样（GCB）和活化B细胞样（ABC）亚型。在患者样本中，高PHB水平与较高的血清LDH（PHB 1和PHB 2）、IPIaa（PHB 2）和Ki-67（PHB 2）表达相关。PHB 1的高表达往往与较短的无事件生存期（EFS）的患者，特别是男性患者。FL 3诱导DLBCL细胞系的凋亡，其与ERK-MNK-eIF 4 E信号传导途径的抑制相关，包括侵袭性双重/三重打击DLBCL细胞系。这导致eIF 4F复合物形成和活性改变，导致Bcl-2和c-Myc表达水平降低。此外，FL 3强烈下调DLBCL细胞Akt蛋白和AKT mRNA水平。FL 3抗肿瘤活性也在鼠异种移植模型中在体内得到证实。结论我们的数据表明，在DLBCL中，PHB过表达与肿瘤侵袭性标志物相关，靶向PHB可能是一种治疗选择，特别是在侵袭性亚型中。
Background Diffuse large B-cell lymphomas (DLBCLs) are aggressive lymphomas accounting for approximately a third of non-Hodgkin lymphomas. Prohibitin 1 (PHB1) and prohibitin 2 (PHB2) are scaffold proteins that promote mitochondria homeostasis and consequently cell survival, but biological functions of cytoplasmic PHBs remain largely unknown in DLBCL. Methods PHB expression was analyzed in 82 DLBCL biopsies and five DLBCL cell lines by immunohistochemistry (IHC) and Western blotting. Pharmacological inhibition of PHB using the synthetic flavagline FL3 was realized in vitro to gain insight PHB cellular functions. Effects of FL3 on DLBCL cell line viability, apoptosis, C-Raf-ERK-MNK-eIF4E signaling pathway and eIF4F complex formation and activity were evaluated by XTT assay, annexin V-FITC/PI dual staining and Western blotting respectively. Subcutaneous DLBCL xenograft model in SCID mice was also performed to determine in vivo FL3 effect. Results As in DLBCL cell lines, PHB1 and PHB2 were expressed in germinal center B-cell-like (GCB) and activated B-cell-like (ABC) subtypes. In patient samples, high PHB levels were associated with higher serum LDH (PHB1 and PHB2), IPIaa (PHB2), and Ki-67 (PHB2) expression. Higher PHB1 expression tends to be associated with shorter event-free survival (EFS) in patients, especially in male patients. FL3 induced apoptosis of DLBCL cell lines that was associated with inhibition of the ERK-MNK-eIF4E signaling pathway, including aggressive double/triple-hit DLBCL cell lines. This resulted in altered eIF4F complex formation and activity leading to a reduction of Bcl-2 and c-Myc expression levels. Moreover, FL3 strongly downregulated DLBCL cellular levels of Akt protein and AKT mRNA. FL3 antitumor activity was also confirmed in vivo in a murine xenograft model. Conclusion Our data indicate that PHB overexpression is associated with markers of tumor aggressiveness in DLBCL, and that targeting PHBs may be a therapeutic option, notably in aggressive subtypes.