Cellular and Molecular Physiology Unit, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.
Istituto Toscano Tumori, Firenze, Italy.
J Cell Physiol. 2018 May;233(5):4282-4293. doi: 10.1002/jcp.26247. Epub 2017 Nov 24.
Neuroblastoma (NB) is a highly malignant pediatric solid tumor where a hypoxic signature correlates with unfavorable patient outcome. The hypoxia-inducible factor (HIF)-1α plays an important role in NB progression, contributing to cell proliferation and invasiveness. RAI belongs to the Shc family proteins, it is mainly neuron specific and protects against cerebral ischemia. RAI is also expressed in several NB cell lines, where it promotes cell survival. In this work, hypoxia differently affected cell survival and pro-apoptotic program in two NB cell lines, either expressing RAI (SKNBE) or not (SKNMC). RAI expression appeared to promote NB cell survival and to reduce some pro-apoptotic markers under hypoxia. Accordingly, the RAI silencing in SKNBE cells resulted in a reduction of cell survival and HIF-1α expression. Furthermore, using SKNMC cells stably expressing RAI, we defined a role of RAI in NB cell responses to hypoxia. Of interest, in hypoxic SKNMC cells expressing RAI HIF-1α protein levels were higher than in control cells. This was associated with a) an increased cell survival; b) an increased expression of anti-apoptotic markers; c) a pro-autophagic and not pro-apoptotic phenotype; and d) an increased metabolic activity. We may conclude that RAI plays an important role in hypoxic signaling in NB cells and the interplay between RAI and HIF-1α may be relevant in the protection of NB cells against hypoxia. Our results may contribute to a further understanding the physiology of NB cells and the molecular mechanisms involved in their survival, with important implications in NB progression.
神经母细胞瘤（NB）是一种高度恶性的小儿实体肿瘤，缺氧特征与患者不良预后相关。缺氧诱导因子（HIF）-1α在 NB 进展中起着重要作用，促进细胞增殖和侵袭性。RAI 属于 Shc 家族蛋白，主要在神经元中表达，可预防脑缺血。RAI 也在几种 NB 细胞系中表达，可促进细胞存活。在这项工作中，缺氧对表达 RAI（SKNBE）或不表达 RAI（SKNMC）的两种 NB 细胞系的细胞存活和促凋亡程序产生了不同的影响。RAI 表达似乎促进了 NB 细胞的存活，并减少了缺氧下的一些促凋亡标志物。因此，SKNBE 细胞中的 RAI 沉默导致细胞存活和 HIF-1α表达减少。此外，使用稳定表达 RAI 的 SKNMC 细胞，我们定义了 RAI 在 NB 细胞对缺氧反应中的作用。有趣的是，在缺氧条件下表达 RAI 的 SKNMC 细胞中，HIF-1α 蛋白水平高于对照细胞。这与以下几个方面有关：a）细胞存活增加；b）抗凋亡标志物表达增加；c）自噬促进而非凋亡表型；和 d）代谢活性增加。我们可以得出结论，RAI 在 NB 细胞的缺氧信号中起着重要作用，RAI 和 HIF-1α 之间的相互作用可能与 NB 细胞对缺氧的保护有关。我们的研究结果可能有助于进一步了解 NB 细胞的生理学以及涉及它们存活的分子机制，这对 NB 进展具有重要意义。
