Mixed Lineage Kinase 3 and cytokine signaling axis in hepatocellular carcinoma

摘要/摘要： 肝细胞癌是包括美国在内的世界范围内癌症相关死亡的主要原因 由于发现时间较晚，有效的治疗选择有限。当务之急是要更好地了解 肝细胞癌进展的分子事件，以便设计合理的治疗策略。 目前的提议集中在一个关键的信号分子，混合血统激酶3(MLK3)，一个成员 MAPK激酶(MAP3K)家族在肝细胞癌中的作用。使用致癌物诱导的肝癌模型，我们 发现MLK3基因敲除(KO)小鼠可以预防肝癌的发生，并显示出减少 与野生型(WT)小鼠相比，小鼠的增殖能力较强。MLK3在一组人肝癌样本中被诱导表达。 此外，在基于细胞的分析中，用PAN-MLK抑制剂CEP-1347处理各种肝癌细胞的次数减少 细胞存活，促进细胞周期停滞和细胞凋亡，提示MLK3在这些过程中可能发挥作用。 此外，MLK3的过度表达增加了细胞因子的表达和释放，进而促进了 MLK3活性，表明MLK3和细胞因子信号之间存在潜在的正反馈环 肝细胞癌进展过程中的轴心。根据这些初步数据，我们假设MLK3代表一种新的 通过与细胞因子信号的串扰参与介导肝肿瘤发生的靶点，以及靶向MLK3- 可用药物抑制的细胞因子轴可能是一种可行的抗肝癌的手段 进步。目前的提议旨在建立MLK3的S在肝癌进展中的作用，而 阐明实现这一目标的潜在机制，以实现对以下方面的机械论见解 MLK3诱导肝细胞癌。作为证明原则，我们将研究MLK3的药理抑制的可行性 使用临床前小鼠模型研究肝细胞癌进展。为了实现我们的目标，我们提出了以下具体目标 目的：(1)阐明MLK3介导的肝癌进展的分子机制；2)建立一种 MLK3和细胞因子轴之间的串扰促进肝细胞癌的进展，以及3)决定 药物抑制MLK3和细胞因子信号转导可减缓肝癌进展。在中国学习的同时 AIMS 1和2有望提供对MLK3信号通路的机械性见解 促进肝细胞癌并确定潜在的下游目标，目标3中的目标将提供重要的原则证明 MLK轴药物抑制剂(CEP-1347)和IL-11体内疗效的临床前信息 抗肝癌进展的拮抗剂。拟议研究的成功结果不仅将提供 对了解MLK3介导肝细胞癌进展机制的新见解 提供有关MLK3抑制剂组合的临床前疗效的信息，可用于 开发有效的以MLK3为基础的治疗策略，用于未来针对肝癌的治疗。

Summary/Abstract: Hepatocellular carcinoma (HCC) is a major cause of cancer-related death worldwide including the United States due to late detection and limited effective therapeutic options. It is imperative to obtain a better understanding of the molecular events underlying the progression of HCC, so that rational therapeutic strategies can be designed. The current proposal focuses on a key signaling molecule, Mixed-Lineage Kinase 3 (MLK3), a member of the MAPK Kinase kinase (MAP3K) family to determine its role in HCC. Using a carcinogen-induced HCC model, we found that MLK3 knockout (KO) mice are protected from developing liver cancer and showed reduced proliferation compared to wild-type (WT) mice. MLK3 expression was induced in a panel of human HCC samples. In addition, in cell-based assays, treatment of various HCC cells with the pan-MLK inhibitor CEP-1347 reduced cell survival, promoted cell cycle arrest and apoptosis, suggesting a potential role of MLK3 in mediating these. Furthermore, overexpression of MLK3 increased the expression and release of cytokines, which in turn promoted MLK3 activity, indicating the presence of a potential positive feedback loop between MLK3 and cytokine signaling axis during HCC progression. Based on these preliminary data, we hypothesize that MLK3 represents a novel target involved in mediating liver tumorigenesis via a crosstalk with cytokine signaling, and targeting of MLK3- cytokine axis by the available pharmacological inhibitors might be a viable means of antagonizing HCC progression. The current proposal is aimed towards establishing MLK3’s role in HCC progression, while elucidating the underlying mechanisms by which this is accomplished, to achieve a mechanistic insight towards MLK3-induced HCC. As a proof-of principle, we will examine the feasibility of pharmacological inhibition of MLK3 on HCC progression using preclinical mouse models. The following specific aims are proposed to achieve our goals: (1) Elucidate the molecular mechanism underlying MLK3-mediated HCC progression, 2) Establish that a crosstalk between MLK3 and cytokine axis promotes HCC progression, and 3) Determine whether pharmacological inhibition of MLK3 and cytokine signaling mitigates liver cancer progression. While studies in Aims 1 and 2 are expected to provide a mechanistic insight towards the signaling pathway by which MLK3 promotes HCC and identify potential downstream targets, those in Aim 3 will provide important proof-of-principle preclinical information on the in vivo efficacy of the pharmacological inhibitor of MLK axis (CEP-1347) and IL-11 antagonist in antagonizing HCC progression. Successful outcome of the proposed studies will not only provide newer insights towards understanding the mechanism by which MLK3 mediates HCC progression, but also provide information on the preclinical efficacy of MLK3 inhibitor combination, which can be utilized towards developing effective MLK3-based therapeutic strategies for targeting HCC in the future.