Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD 21231, USA.
Department of Medicine, University of Maryland School of Medicine, Baltimore MD 21201, USA.
Sci Rep. 2017 Jan 10;7:40070. doi: 10.1038/srep40070.
Functional reactivation of p53 pathway, although arduous, can potentially provide a broad-based strategy for cancer therapy owing to frequent p53 inactivation in human cancer. Using a phosphoprotein-screening array, we found that Benzyl Isothiocynate, (BITC) increases p53 phosphorylation in breast cancer cells and reveal an important role of ERK and PRAS40/MDM2 in BITC-mediated p53 activation. We show that BITC rescues and activates p53-signaling network and inhibits growth of p53-mutant cells. Mechanistically, BITC induces p73 expression in p53-mutant cells, disrupts the interaction of p73 and mutant-p53, thereby releasing p73 from sequestration and allowing it to be transcriptionally active. Furthermore, BITC-induced p53 and p73 axes converge on tumor-suppressor LKB1 which is transcriptionally upregulated by p53 and p73 in p53-wild-type and p53-mutant cells respectively; and in a feed-forward mechanism, LKB1 tethers with p53 and p73 to get recruited to p53-responsive promoters. Analyses of BITC-treated xenografts using LKB1-null cells corroborate in vitro mechanistic findings and establish LKB1 as the key node whereby BITC potentiates as well as rescues p53-pathway in p53-wild-type as well as p53-mutant cells. These data provide first in vitro and in vivo evidence of the integral role of previously unrecognized crosstalk between BITC, p53/LKB1 and p73/LKB1 axes in breast tumor growth-inhibition.
尽管功能再激活 p53 通路具有挑战性，但由于人类癌症中 p53 失活频繁，它可能为癌症治疗提供一种广泛的策略。使用磷酸化蛋白筛选阵列，我们发现苄基异硫氰酸酯（BITC）可增加乳腺癌细胞中的 p53 磷酸化，并揭示 ERK 和 PRAS40/MDM2 在 BITC 介导的 p53 激活中的重要作用。我们表明，BITC 可挽救和激活 p53 信号网络并抑制 p53 突变细胞的生长。在机制上，BITC 在 p53 突变细胞中诱导 p73 表达，破坏 p73 和突变型 p53 的相互作用，从而使 p73 从隔离中释放出来并使其具有转录活性。此外，BITC 诱导的 p53 和 p73 轴汇聚于肿瘤抑制因子 LKB1，LKB1 分别由 p53 和 p73 在 p53 野生型和 p53 突变型细胞中转录上调；并且在正反馈机制中，LKB1 与 p53 和 p73 结合，被募集到 p53 反应性启动子上。使用 LKB1 缺失细胞对 BITC 处理的异种移植物进行分析，证实了体外机制研究结果，并确立了 LKB1 作为关键节点，通过该节点，BITC 增强了 p53 野生型和 p53 突变型细胞中 p53 通路的作用，以及对 p53 通路的挽救作用。这些数据提供了体内和体外证据，证明了以前未被识别的 BITC、p53/LKB1 和 p73/LKB1 轴之间的整体相互作用在乳腺癌肿瘤生长抑制中的作用。
