ERK3 Kinase Signaling in Lung Cancer

 描述（由申请人提供）：肿瘤抑制基因LKB 1经常因肺癌突变而失活，这通常与伴随的激活KRas突变相关。LKB 1失活与晚期肿瘤进展和转移正相关。虽然LKB 1主要通过靶向AMPK/mTOR和p53信号通路来调节癌细胞生长，但LKB 1调节肿瘤侵袭和转移的分子机制尚不清楚。有趣的是，在LKB 1缺失后，ERK 3（一种非典型MAP激酶）在KRasG 12 D诱导的肿瘤和人肺癌细胞中高度上调。最近发现ERK 3在肺癌中过表达，并通过上调基质金属蛋白酶（MMP）基因表达促进肺癌细胞的迁移和侵袭。与研究充分的经典MAPK（如ERK 1/2）相比，对ERK 3信号传导（基因表达和激酶激活）的分子调控知之甚少。重要的是，在我们的初步研究中鉴定的ERK 3相互作用蛋白的独创性途径分析表明，ERK 3与TGF β（或Wnt）/TAK 1信号传导和RhoGDI信号传导高度相关。此外，来自体外共培养实验的初步数据表明，肺癌细胞中LKB 1的消耗促进了M β向M2型的转化; M2 M β然后产生高水平的TGF β 1和Wnt 2，其可以反过来通过激活TAK 1和ERK 3而作用于肿瘤。基于这些发现，我们假设ERK 3信号在肺肿瘤微环境中LKB 1丢失后上调; ERK 3信号的上调然后促进肺肿瘤进展和转移。为了检验这一假设，提出了以下具体目标。1）。在培养的肺癌细胞系统中，确定ERK 3信号传导的分子调控：c-Jun介导的基因表达和TAK-1介导的激酶激活对TGF β 1/Wnt信号的响应。2）。利用肺特异性KRasG 12 D/LKB 1缺陷肿瘤模型，体内检测肿瘤细胞中LKB 1缺失后，ERK 3信号传导通过c-Jun介导的ERK 3基因上调和TAK-1介导的ERK 3信号传导途径激活而上调，以响应M2型TAM分泌的TGF β s和/或Wnt的刺激。3）。通过在KRasG 12 D肺肿瘤小鼠模型中条件性过表达ERK 3或在肺组织特异性KRasG 12 D/LKB 1-null小鼠模型中条件性敲除ERK 3来确定ERK 3在肺肿瘤进展和转移中的作用。本研究的目的是阐明ERK 3信号通路，并确定其在肺肿瘤进展和转移中的作用。这项工作有望将ERK 3定义为一种新的诊断标记物和/或治疗晚期肺癌的治疗药物靶点。

 DESCRIPTION (provided by applicant): Tumor suppressor gene LKB1 is frequently inactivated by mutations in lung cancer, which is often associated with concomitant activating KRas mutation. LKB1 inactivation is positively associated with advanced tumor progression and metastasis. While it is well-documented that LKB1 regulates cancer cell growth mainly through targeting AMPK/mTOR and p53 signaling pathways, the molecular mechanisms underlying the regulation of tumor invasion and metastasis by LKB1 are poorly understood. Interestingly, upon the loss of LKB1, ERK3, an atypical MAP kinase, is highly upregulated in KRasG12D-induced tumors and in human lung cancer cells. ERK3 was recently shown to be overexpressed in lung cancer and promote lung cancer cell migration and invasion by upregulating matrix metalloproteinase (MMP) gene expression. In contrast to the well-studied classic MAPKs, such as ERK1/2, little is known about the molecular regulation of ERK3 signaling (gene expression and kinase activation). Importantly, ingenuity pathway analysis of ERK3 interacting proteins identified in our pilot study shows that ERK3 is highly associated with TGFß (or Wnt)/TAK1 signaling and RhoGDI signaling. In addition, preliminary data from in vitro co-culture experiments demonstrate that depletion of LKB1 in lung cancer cells facilitates the conversion of MФs to M2 type; M2 MФs then produce high levels of TGFß1 and Wnt2 that may in turn act on tumors in activating TAK1 and ERK3. Based on these findings, we hypothesize that ERK3 signaling is upregulated upon the loss of LKB1 in lung tumor microenvironment; upregulation of ERK3 signaling then promotes lung tumor progression and metastasis. To test this hypothesis, the following specific aims are proposed. 1). To define the molecular regulation of ERK3 signaling: c-Jun-mediated gene expression and TAK-1-mediated kinase activation in response to TGFß/Wnt signals, in cultured lung cancer cell systems. 2). To test in vivo the idea that ERK3 signaling is upregulated upon the loss of LKB1 in tumor cells through c-Jun-mediated ERK3 gene upregulation and TAK-1-mediated activation of ERK3 signaling pathway in response to the stimulation of TGFßs and/or Wnts secreted by M2 type TAMs, utilizing a lung-specific KRasG12D/LKB1-deficient tumor model. 3). To determine the roles of ERK3 in lung tumor progression and metastasis by conditionally overexpressing ERK3 in KRasG12D lung tumor mouse model or conditionally knocking out ERK3 in lung tissue-specific KRasG12D/LKB1-null mouse model. The objective of this proposal is to elucidate ERK3 signaling pathway and to determine its role in lung tumor progression and metastasis. The proposed work is anticipated to define ERK3 as a novel diagnostic marker and/or a therapeutic drug target for the treatment of advanced lung cancer.