Tufano Martina, Cesaro Elena, Martinelli Rosanna, Pacelli Roberto, Romano Simona, Romano Maria Fiammetta
Dipartimento di Medicina Molecolaree Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Naples, Italy.
Dipartimento di Medicina, Chirurgia ed Odontoiatria, Università degli Studi di Salerno, Baronissi, Italy.
Front Cell Dev Biol. 2021 Sep 13;9:718947. doi: 10.3389/fcell.2021.718947. eCollection 2021.
Melanoma is one of the most immunogenic tumors and has the highest potential to elicit specific adaptive antitumor immune responses. Immune cells induce apoptosis of cancer cells either by soluble factors or by triggering cell-death pathways. Melanoma cells exploit multiple mechanisms to escape immune system tumoricidal control. FKBP51 is a relevant pro-oncogenic factor of melanoma cells supporting NF-κB-mediated resistance and cancer stemness/invasion epigenetic programs. Herein, we show that FKBP51-silencing increases TNF-related apoptosis-inducing ligand (TRAIL)-R2 (DR5) expression and sensitizes melanoma cells to TRAIL-induced apoptosis. Consistent with the general increase in histone deacetylases, as by the proteomic profile, the immune precipitation assay showed decreased acetyl-Yin Yang 1 (YY1) after FKBP51 depletion, suggesting an impaired repressor activity of this transcription factor. ChIP assay supported this hypothesis. Compared with non-silenced cells, a reduced acetyl-YY1 was found on the DR5 promoter, resulting in increased DR5 transcript levels. Using Crispr/Cas9 knockout (KO) melanoma cells, we confirmed the negative regulation of DR5 by FKBP51. We also show that KO cells displayed reduced levels of acetyl-EP300 responsible for YY1 acetylation, along with reduced acetyl-YY1. Reconstituting FKBP51 levels contrasted the effects of KO on DR5, acetyl-YY1, and acetyl-EP300 levels. In conclusion, our finding shows that FKBP51 reduces DR5 expression at the transcriptional level by promoting YY1 repressor activity. Our study supports the conclusion that targeting FKBP51 increases the expression level of DR5 and sensitivity to TRAIL-induced cell death, which can improve the tumoricidal action of immune cells.
黑色素瘤是免疫原性最强的肿瘤之一，具有引发特异性适应性抗肿瘤免疫反应的最大潜力。免疫细胞通过可溶性因子或触发细胞死亡途径诱导癌细胞凋亡。黑色素瘤细胞利用多种机制逃避免疫系统的杀肿瘤控制。FKBP51是黑色素瘤细胞的一种相关促癌因子，支持NF-κB介导的抗性以及癌症干性/侵袭性表观遗传程序。在此，我们表明FKBP51沉默可增加肿瘤坏死因子相关凋亡诱导配体（TRAIL）-R2（DR5）的表达，并使黑色素瘤细胞对TRAIL诱导的凋亡敏感。与蛋白质组学分析显示的组蛋白脱乙酰酶普遍增加一致，免疫沉淀试验表明FKBP51缺失后乙酰化阴阳1（YY1）减少，表明该转录因子的阻遏活性受损。染色质免疫沉淀试验支持了这一假设。与未沉默的细胞相比，在DR5启动子上发现乙酰化YY1减少，导致DR5转录水平增加。使用Crispr/Cas9基因敲除（KO）黑色素瘤细胞，我们证实了FKBP51对DR5的负调控。我们还表明，KO细胞中负责YY1乙酰化的乙酰化EP300水平降低，同时乙酰化YY1也降低。恢复FKBP51水平可抵消KO对DR5、乙酰化YY1和乙酰化EP300水平的影响。总之，我们的发现表明FKBP51通过促进YY1阻遏活性在转录水平上降低DR5表达。我们的研究支持这样的结论，即靶向FKBP51可增加DR5的表达水平以及对TRAIL诱导的细胞死亡的敏感性，这可以改善免疫细胞的杀肿瘤作用。
