De los Santos Maxy, Zambrano Alberto, Aranda Ana
Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, Madrid, Spain.
Mol Cancer Ther. 2007 Apr;6(4):1425-32. doi: 10.1158/1535-7163.MCT-06-0623.
All-trans retinoic acid (RA) causes differentiation of neuroblastoma cells, and retinoids have been used in clinical trials in children with advanced neuroblastoma. Combination of RA with histone deacetylase inhibitors (HDACi) could result in improved antitumorigenic activity. We have examined the effect of the HDACi trichostatin A (TSA), sodium butyrate, and suberoylanilide hydroxamic acid (SAHA), alone and in combination with RA in human neuroblastoma SH-SY5Y cells. At concentrations that cause sustained increase of histone H3 acetylation, HDACi produced extensive apoptotic cell death as shown by flow cytometry analysis and induction of poly(ADP-ribose) polymerase proteolysis. HDACi inhibited SH-SY5Y cell growth at a much larger extent than RA. This compound did not cause apoptosis and did not further increase HDACi-mediated cell death. In contrast, both types of drugs cooperated to inhibit cell growth, although synergistic effects were not found. In surviving cells, HDACi repressed cyclin D1 expression and increased the cyclin kinase inhibitors (CKI) p21(Waf1/Cip1) and p27(Kip1). Cyclin D1 was not affected by RA, but this retinoid also increased CKI levels. Induction of p21(Waf1/Cip1) and p27(Kip1) by HDACi was further enhanced in the presence of RA. This effect seems to be at least partially due to transcriptional stimulation of CKI gene expression because both types of drugs cooperated to increase CKI mRNA levels and to activate the CKI promoters in transient transfection assays. These results show the strong antitumorigenic effects of HDACi in neuroblastoma cells and reinforce the idea that combination therapy could be useful to inhibit tumor growth.
全反式维甲酸（RA）可诱导神经母细胞瘤细胞分化，类视黄醇已用于晚期神经母细胞瘤患儿的临床试验。RA与组蛋白脱乙酰酶抑制剂（HDACi）联合使用可提高抗肿瘤活性。我们研究了HDACi曲古抑菌素A（TSA）、丁酸钠和伏立诺他（SAHA）单独及与RA联合对人神经母细胞瘤SH-SY5Y细胞的影响。在导致组蛋白H3乙酰化持续增加的浓度下，HDACi可导致广泛的凋亡性细胞死亡，这通过流式细胞术分析和聚（ADP-核糖）聚合酶蛋白水解的诱导得以证实。HDACi比RA更能抑制SH-SY5Y细胞的生长。该化合物不会导致细胞凋亡，也不会进一步增加HDACi介导的细胞死亡。相比之下，尽管未发现协同作用，但两种药物协同抑制细胞生长。在存活细胞中，HDACi抑制细胞周期蛋白D1的表达，并增加细胞周期蛋白激酶抑制剂（CKI）p21（Waf1/Cip1）和p27（Kip1）的水平。细胞周期蛋白D1不受RA的影响，但这种类视黄醇也会增加CKI水平。在RA存在的情况下，HDACi对p21（Waf1/Cip1）和p27（Kip1）的诱导作用进一步增强。这种作用似乎至少部分归因于CKI基因表达的转录刺激，因为在瞬时转染试验中，两种药物协同增加CKI mRNA水平并激活CKI启动子。这些结果表明HDACi在神经母细胞瘤细胞中具有强大的抗肿瘤作用，并强化了联合治疗可能有助于抑制肿瘤生长的观点。
