Mechanistic Analysis of an Extracellular Signal–Regulated Kinase 2–Interacting Compound that Inhibits Mutant BRAF-Expressing Melanoma Cells by Inducing Oxidative Stress
作者:Ramon Martinez、Weiliang Huang、Ramin Samadani、Bryan Mackowiak、Garrick Centola、Lijia Chen、Ivie L. Conlon、Kellie Hom、Maureen A. Kane、Steven Fletcher、Paul Shapiro
DOI:10.1124/jpet.120.000266
日期:2021.1
Constitutively active extracellular signal–regulated kinase (ERK) 1/2 signaling promotes cancer cell proliferation and survival. We previously described a class of compounds containing a 1,1-dioxido-2,5-dihydrothiophen-3-yl 4-benzenesulfonate scaffold that targeted ERK2 substrate docking sites and selectively inhibited ERK1/2-dependent functions, including activator protein-1–mediated transcription and growth of cancer cells containing active ERK1/2 due to mutations in Ras G-proteins or BRAF, Proto-oncogene B-RAF (Rapidly Acclerated Fibrosarcoma) kinase. The current study identified chemical features required for biologic activity and global effects on gene and protein levels in A375 melanoma cells containing mutant BRAF (V600E). Saturation transfer difference-NMR and mass spectrometry analyses revealed interactions between a lead compound ( SF-3-030 ) and ERK2, including the formation of a covalent adduct on cysteine 252 that is located near the docking site for ERK/FXF (DEF) motif for substrate recruitment. Cells treated with SF-3-030 showed rapid changes in immediate early gene levels, including DEF motif–containing ERK1/2 substrates in the Fos family. Analysis of transcriptome and proteome changes showed that the SF-3-030 effects overlapped with ATP-competitive or catalytic site inhibitors of MAPK/ERK Kinase 1/2 (MEK1/2) or ERK1/2. Like other ERK1/2 pathway inhibitors, SF-3-030 induced reactive oxygen species (ROS) and genes associated with oxidative stress, including nuclear factor erythroid 2–related factor 2 (NRF2). Whereas the addition of the ROS inhibitor N -acetyl cysteine reversed SF-3-030 –induced ROS and inhibition of A375 cell proliferation, the addition of NRF2 inhibitors has little effect on cell proliferation. These studies provide mechanistic information on a novel chemical scaffold that selectively regulates ERK1/2-targeted transcription factors and inhibits the proliferation of A375 melanoma cells through a ROS-dependent mechanism. SIGNIFICANCE STATEMENT Constitutive activation of the extracellular signal–regulated kinase (ERK1/2) pathway drives the proliferation and survival of many cancer cell types. Given the diversity of cellular functions regulated by ERK1/2, the current studies have examined the mechanism of a novel chemical scaffold that targets ERK2 near a substrate binding site and inhibits select ERK functions. Using transcriptomic and proteomic analyses, we provide a mechanistic basis for how this class of compounds inhibits melanoma cells containing mutated BRAF and active ERK1/2.
细胞外信号调节激酶(ERK)1/2 信号的持续活跃促进了癌细胞的增殖和存活。我们以前曾描述过一类含有 1,1-二氧代-2,5-二氢噻吩-3-基 4-苯磺酸盐支架的化合物,它们以 ERK2 底物对接位点为靶点,选择性地抑制 ERK1/2 依赖性功能,包括激活蛋白-1 介导的转录,以及因 Ras G 蛋白或 BRAF、原癌基因 B-RAF(快速增殖性纤维肉瘤)激酶突变而导致含有活性 ERK1/2 的癌细胞的生长。目前的研究确定了生物活性所需的化学特征,以及对含有突变 BRAF(V600E)的 A375 黑色素瘤细胞中基因和蛋白质水平的整体影响。饱和转移差分核磁共振和质谱分析揭示了一种先导化合物(SF-3-030)与 ERK2 之间的相互作用,包括在半胱氨酸 252 上形成共价加合物,该半胱氨酸 252 位于 ERK/FXF (DEF) 基序的对接位点附近,用于底物招募。用 SF-3-030 处理的细胞显示出即时早期基因水平的快速变化,包括 Fos 家族中含有 DEF 基序的 ERK1/2 底物。对转录组和蛋白质组变化的分析表明,SF-3-030 的作用与 MAPK/ERK 激酶 1/2(MEK1/2)或 ERK1/2 的 ATP 竞争性或催化位点抑制剂重叠。与其他 ERK1/2 通路抑制剂一样,SF-3-030 也会诱导活性氧(ROS)和与氧化应激相关的基因,包括核因子红细胞 2 相关因子 2(NRF2)。加入 ROS 抑制剂 N -乙酰半胱氨酸可逆转 SF-3-030 诱导的 ROS 和对 A375 细胞增殖的抑制,而加入 NRF2 抑制剂对细胞增殖几乎没有影响。这些研究提供了一种新型化学支架的机理信息,这种支架可选择性地调节 ERK1/2 靶向转录因子,并通过 ROS 依赖性机制抑制 A375 黑色素瘤细胞的增殖。 意义说明 细胞外信号调节激酶(ERK1/2)通路的持续激活驱动着许多癌细胞类型的增殖和存活。鉴于ERK1/2调控的细胞功能多种多样,目前的研究考察了一种新型化学支架的作用机制,这种化学支架靶向底物结合位点附近的ERK2,并抑制ERK的某些功能。通过转录组和蛋白质组分析,我们为这类化合物如何抑制含有突变 BRAF 和活性 ERK1/2 的黑色素瘤细胞提供了机理基础。