Paxillin as a Liaison between Extranuclear and Intranuclear Steroid Signaling

描述(申请人提供)：几十年来，研究人员已经知道，细胞质中的信号事件可以对细胞核中的信号事件产生深远的影响；然而，关于这种细胞质到核(从外到内)的串扰是如何调节的细节仍不清楚。我们最近发现，以调节细胞骨架重塑而闻名的巴西林分子，在前列腺癌细胞的核外和核内信号之间起着至关重要的联系。具体地说，我们发现巴西林是核外ERK激活所必需的，以响应多种输入，包括通过膜定位的雄激素受体(AR)的非基因组雄激素信号以及通过受体酪氨酸激酶(RTK)的生长因子。一旦被激活，ERK就会调节丝氨酸残基上的帕西林的磷酸化，在这一点上，磷酸丝氨酸-帕西林进入细胞核，并介导AR和Erk依赖的转录。事实上，如果我们阻止ERK介导的帕克西林的磷酸化，那么帕克西林就不会进入细胞核，雄激素和生长因子依赖的转录被取消，前列腺癌细胞不会对任何这些激动剂产生反应而增殖。重要的是，我们发现与正常前列腺组织相比，前列腺癌组织中细胞质和核内磷酸丝氨酸-帕西林的表达上调，这意味着帕西林在肿瘤中过度活跃。总之，我们的数据表明，帕西林可能是前列腺癌生长的关键介质，因此是一个可行的诊断和治疗靶点。此外，由于帕克西林实际上调节每一种肿瘤细胞系中ERK的激活和下游效应，无论来源如何，我们推测帕克西林可能是ERK作用的一般调节者，远远超出前列腺。在这项提案中，我们将继续关注前列腺癌模型，以进一步阐明帕克西林如何调节生长因子、雄激素和其他类固醇对“外向内”信号的反应。此外，我们还将研究帕克西林对前列腺癌体内生长的影响，并将更密切地研究帕克西林在人类前列腺癌中的表达和激活。最后，我们将测试一种新的方法，即在胞核中特定调节帕西林的作用，同时避免其在细胞质中的作用，从而将核帕西林作为治疗去势敏感型和抗去势前列腺癌的靶点。 成长。

DESCRIPTION (provided by applicant): Researchers have known for decades that signaling events in the cytoplasm can have profound effects on signaling events in the nucleus; however details regarding how this cytoplasm to nuclear ("outside-inside") cross talk is regulated are stil not known. We have recently discovered that paxillin, a molecule best known for regulating cytoskeletal remodeling, is a critical liaison between extranuclear and intranuclear signaling in prostate cancer cells. Specifically, we find that paxillin is necessary for extranuclear Erk activation in response to multiple inputs, including nongenomic androgen signaling via membrane-localized androgen receptors (ARs) as well as growth factors via Receptor Tyrosine Kinases (RTKs). Once activated, Erk then regulates phosphorylation of paxillin on serine residues, at which point phosphoserine-paxillin travels to the nucleus and mediates AR- and Erk-dependent transcription. In fact, if we prevent this Erk-mediated phosphorylation of paxillin, then paxillin will not enter the nucleus, androgen and growth factor-dependent transcription is abrogated, and prostate cancer cells do not proliferate in response to any of these agonists. Importantly, we find that cytoplasmic paxillin and nuclear phosphoserine-paxillin expression are upregulated in human prostate cancer relative to normal prostate tissue, implying that paxillin is over-active in tumors. Together, our data suggest that paxillin might be a key mediator of prostate cancer growth and therefore a viable diagnostic and therapeutic target. Furthermore, since paxillin actually regulates Erk activation and downstream effects in every tumor cell line tested, regardless of origin, we postulate that paxillin might be a general regulator of Erk action well beyond the prostate. In this proposal, we will continue to focus on prostate cancer models to further elucidate how paxillin regulates "outside-inside" signaling in response to growth factors, androgens, and other steroids. In addition, we will examine paxillin effects on prostate cancer growth in-vivo, and will more closely examine paxillin expression and activation in human prostate cancer. Finally, we will test novel means of specifically regulating paxillin's actions in the nucleus while sparing it's actions in the cytoplasm, thereby using nuclear paxillin as a target for the treatment of both castration-sensitive and castration-resistant prostate cancer growth.