Bexarotene activates the p53/p73 pathway in human cutaneous T-cell lymphoma
Bexarotene activates the p53/p73 pathway in human cutaneous T-cell lymphoma
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DOI：
10.1111/j.1365-2133.2008.08931.x
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发表时间：
2009-03-01
影响因子：
10.3
通讯作者：
Asumendi, A.
中科院分区：
文献类型：
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作者：
Nieto-Rementeria, N.;Perez-Yarza, G.;Asumendi, A.
Bexarotene是第一个被批准用于治疗皮肤t细胞淋巴瘤（CTCL）的合成类维甲酸X受体选择性类维甲酸（rexinoid）。然而，人们对其发挥抗癌作用的信号通路知之甚少。目的：探讨贝沙罗汀在CTCL细胞系中的作用，并阐明其抗肿瘤作用的潜在分子途径。使用细胞系ht -78、HH和MJ。用XTT法测定细胞活力。用甲基纤维素克隆实验研究了贝沙罗汀处理后细胞的自我更新潜能。流式细胞术分析其对细胞周期、Ki-67表达及凋亡诱导的影响。Western blot和免疫荧光法检测细胞周期和凋亡相关蛋白的表达。Bexarotene诱导HH和ht -78细胞活力丧失和更明显的克隆原性增殖抑制，而MJ系表现出抗性。贝沙罗汀在敏感细胞系中上调和激活Bax，但不足以表明明显的细胞凋亡。相反，所有数据都表明，类黄酮的主要机制作用是抑制增殖，而不是细胞凋亡。贝沙罗汀通过调节关键检查点蛋白信号G(1)和G(2)/M阻滞。我们进一步发现贝沙罗汀通过在Ser15位点磷酸化激活p53，从而影响p53与启动子的结合以阻止细胞周期，诱导p73上调，同时也调节一些p53/p73下游靶基因，如p21、Bax、survivin和cdc2。贝沙罗汀介导的共济失调毛细血管扩张突变蛋白（ATM）在所有研究品系中的激活表明ATM可能是p53/p73上游激活因子。我们的数据首次表明贝沙罗汀在CTCL中的作用主要是通过触发p53/p73依赖的细胞周期抑制途径，可能是通过上游ATM激活。因此，贝沙罗汀调节基因是评估CTCL患者治疗反应的潜在生物标志物。
Bexarotene is the first synthetic retinoid X receptor-selective retinoid (rexinoid) approved for the treatment of cutaneous T-cell lymphoma (CTCL). However, little is known about the signalling pathways by which it exerts its anticarcinogenic effect.To characterize the effects of bexarotene in CTCL cell lines and elucidate the underlying molecular pathways of its antineoplastic effect.The cell lines Hut-78, HH and MJ were used. Cell viability was assessed with the XTT assay. The self-renewal potential of cells after bexarotene treatment was studied with the methylcellulose clonogenic assay. Flow cytometry was used to analyse the effects on cell cycle, Ki-67 expression and apoptosis induction. Cell cycle and apoptosis-related protein expression were determined by Western blot and immunofluorescence.Bexarotene induced a loss of viability and more pronounced inhibition of clonogenic proliferation in HH and Hut-78 cells, whereas the MJ line exhibited resistance. Bexarotene upregulated and activated Bax in sensitive lines, although not enough to signal significant apoptosis. Instead, all data point to the inhibition of proliferation, rather than apoptosis, as the main mechanistic action of the rexinoid. Bexarotene signals both G(1) and G(2)/M arrest by the modulation of critical checkpoint proteins. We further found that bexarotene activates p53 by phosphorylation at Ser15, which influences the binding of p53 to promoters for cell cycle arrest, induces p73 upregulation, and, in concordance, also modulates some p53/p73 downstream target genes, such as p21, Bax, survivin and cdc2. Bexarotene-mediated ataxia telangiectasia mutated protein (ATM) activation in all studied lines suggests that ATM is likely to be the p53/p73 upstream activator.Our data indicate for the first time that bexarotene exerts its effect in CTCL mainly by triggering the p53/p73-dependent cell cycle inhibition pathway, probably by upstream ATM activation. Therefore, bexarotene-modulated genes represent potential biomarkers to assess the response to treatment of patients with CTCL.