Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, USA.
Mol Cancer. 2013 May 9;12:39. doi: 10.1186/1476-4598-12-39.
The aryl hydrocarbon receptor (AhR) ligand 6-Formylindolo(3,2-b)carbazole (FICZ) has received increasing attention since its identification as an endogenous AhR ligand and a photoproduct of tryptophan. FICZ and its metabolites have been detected in human fluids. We recently reported that AhR promotes retinoic acid (RA)-induced granulocytic differentiation of HL-60 myeloblastic leukemia cells by restricting the nuclear abundance of the stem cell associated transcription factor Oct4. The standard clinical management of acute promyelocytic leukemia (APL) is differentiation induction therapy using RA. But RA is not effective for other myeloid leukemias, making the mechanism of RA-induced differentiation observed in a non-APL myeloid leukemia of interest. To our knowledge, this is the first study regarding the influence of FICZ on RA-induced differentiation in any type of leukemic blasts.
Using flow cytometry and Western blotting assays, we determined the effects of FICZ on RA-induced differentiation of HL-60 human leukemia cells. All experiments were performed in triplicate. The groups RA and FICZ + RA were compared using the Paired-Samples T-Test. Western blot figures present the typical blots.
We demonstrate that FICZ enhances RA-induced differentiation, assessed by the expression of the membrane differentiation marker CD11b; cell cycle arrest; and the functional differentiation marker, inducible-oxidative metabolism. FICZ causes changes in signaling events that are known to drive differentiation, and notably augments the RA-induced sustained activation of the RAF/MEK/ERK axis of the mitogen-activated protein kinase (MAPK) cascade. FICZ also augments expression of the known MAPK signaling regulatory molecules c-Cbl, VAV1, pY458 p85 PI3K, Src-family kinases (SFKs), and IRF-1, a transcription factor associated with this putative signalsome that promotes RA-induced differentiation. Moreover, FICZ in combination with RA also increases expression of AhR and even more so of both Cyp1A2 and p47phox, which are known to be transcriptionally regulated by AhR. pY1021 PDGFRβ, a marker associated with retinoic acid syndrome was also increased.
Our data suggest that FICZ modulates intracellular signaling pathways and enhances RA-induced differentiation.
芳基烃受体（AhR）配体 6-甲酰基吲哚并[3,2-b]咔唑（FICZ）自被鉴定为内源性 AhR 配体和色氨酸的光产物以来，受到了越来越多的关注。FICZ 及其代谢产物已在人体液中被检测到。我们最近报道称，AhR 通过限制与干细胞相关的转录因子 Oct4 的核丰度，促进维甲酸（RA）诱导的 HL-60 髓样白血病细胞的粒细胞分化。急性早幼粒细胞白血病（APL）的标准临床治疗是使用 RA 进行分化诱导治疗。但是，RA 对其他髓样白血病无效，这使得在非 APL 髓样白血病中观察到的 RA 诱导分化的机制成为研究热点。据我们所知，这是第一项关于 FICZ 对任何类型白血病细胞中 RA 诱导分化影响的研究。
我们使用流式细胞术和 Western blot 分析来确定 FICZ 对 HL-60 人白血病细胞中 RA 诱导分化的影响。所有实验均重复进行三次。使用配对样本 T 检验比较 RA 组和 FICZ+RA 组。Western blot 图呈现了典型的印迹。
我们证明，FICZ 通过表达膜分化标志物 CD11b、细胞周期阻滞和诱导氧化代谢的功能性分化标志物，增强 RA 诱导的分化。FICZ 引起已知驱动分化的信号事件的变化，特别是增强 RAF/MEK/ERK 丝裂原激活蛋白激酶（MAPK）级联的持续激活。FICZ 还增强了已知的 MAPK 信号调节分子 c-Cbl、VAV1、pY458 p85 PI3K、Src 家族激酶（SFKs）和 IRF-1 的表达，IRF-1 是与该假定信号体相关的转录因子，可促进 RA 诱导的分化。此外，FICZ 与 RA 联合使用还会增加 AhR 的表达，甚至增加 Cyp1A2 和 p47phox 的表达，这两种物质已知受 AhR 转录调控。与维甲酸综合征相关的标志物 pY1021 PDGFRβ也增加了。
我们的数据表明，FICZ 调节细胞内信号通路并增强 RA 诱导的分化。
