Background Quiescence (G0) is a transient, cell cycle-arrested state. By entering G0, cancer cells survive unfavorable conditions such as chemotherapy and cause relapse. While G0 cells have been studied at the transcriptome level, how post-transcriptional regulation contributes to their chemoresistance remains unknown. Results We induce chemoresistant and G0 leukemic cells by serum starvation or chemotherapy treatment. To study post-transcriptional regulation in G0 leukemic cells, we systematically analyzed their transcriptome, translatome, and proteome. We find that our resistant G0 cells recapitulate gene expression profiles of in vivo chemoresistant leukemic and G0 models. In G0 cells, canonical translation initiation is inhibited; yet we find that inflammatory genes are highly translated, indicating alternative post-transcriptional regulation. Importantly, AU-rich elements (AREs) are significantly enriched in the upregulated G0 translatome and transcriptome. Mechanistically, we find the stress-responsive p38 MAPK-MK2 signaling pathway stabilizes ARE mRNAs by phosphorylation and inactivation of mRNA decay factor, Tristetraprolin (TTP) in G0. This permits expression of ARE mRNAs that promote chemoresistance. Conversely, inhibition of TTP phosphorylation by p38 MAPK inhibitors and non-phosphorylatable TTP mutant decreases ARE-bearing TNFα and DUSP1 mRNAs and sensitizes leukemic cells to chemotherapy. Furthermore, co-inhibiting p38 MAPK and TNFα prior to or along with chemotherapy substantially reduces chemoresistance in primary leukemic cells ex vivo and in vivo. Conclusions These studies uncover post-transcriptional regulation underlying chemoresistance in leukemia. Our data reveal the p38 MAPK-MK2-TTP axis as a key regulator of expression of ARE-bearing mRNAs that promote chemoresistance. By disrupting this pathway, we develop an effective combination therapy against chemosurvival.

中文翻译：

---

静止白血病细胞中富含 AU 元素和 TTP 的化学抗性转录后程序

背景静止 (G0) 是一种短暂的细胞周期停滞状态。通过进入 G0，癌细胞在化疗等不利条件下存活并导致复发。虽然已经在转录组水平研究了 G0 细胞，但转录后调节如何促进其化学抗性仍然未知。结果我们通过血清饥饿或化学疗法诱导化学抗性和G0白血病细胞。为了研究 G0 白血病细胞的转录后调控，我们系统地分析了它们的转录组、翻译组和蛋白质组。我们发现我们的抗性 G0 细胞概括了体内化学抗性白血病和 G0 模型的基因表达谱。在 G0 细胞中，经典翻译起始被抑制；然而我们发现炎症基因被高度翻译，表明替代的转录后调控。重要的是，富含 AU 的元素 (ARE) 在上调的 G0 翻译组和转录组中显着丰富。从机制上讲，我们发现应激反应性 p38 MAPK-MK2 信号通路通过磷酸化和失活 mRNA 衰减因子三四脯氨酸 (TTP) 在 G0 中稳定 ARE mRNA。这允许促进化学抗性的 ARE mRNA 的表达。相反，p38 MAPK 抑制剂和非磷酸化 TTP 突变体对 TTP 磷酸化的抑制会降低携带 ARE 的 TNFα 和 DUSP1 mRNA，并使白血病细胞对化疗敏感。此外，在化疗之前或与化疗一起共同抑制 p38 MAPK 和 TNFα 可显着降低体外和体内原代白血病细胞的化学抗性。结论 这些研究揭示了白血病化疗耐药性的转录后调控。我们的数据显示 p38 MAPK-MK2-TTP 轴是促进化学抗性的含 ARE mRNA 表达的关键调节因子。通过破坏这一途径，我们开发了一种有效的联合疗法来对抗化学存活。