Understanding the roles of PTM's in modulating molecular functions of lysyl oxidase-like 2 in breast cancer cells

描述（由申请人提供）：赖氨酰氧化酶样2（L0 XL 2）预期是基底样乳腺癌中有希望的新治疗靶点，因为它在这些癌细胞和组织中高度上调，并且因为通过shRNA抑制L0 XL 2的产生或用其特异性抗体治疗已显示在组织培养物和动物模型中延缓肿瘤进展和转移/侵袭。L0 XL 2属于赖氨酰氧化酶（LOX）家族，其由赖氨酸酪氨酰醌（LTQ）依赖性铜胺氧化酶组成。通常认为L0 XL 2通过其胺氧化酶活性催化ECM硬化。然而，最近也提出了L0 XL 2的细胞内功能。迄今为止，还没有LOXL 2或LOX家族任何成员的结构，并且已经进行了非常有限的LOXL 2的基础生物化学和生物学研究。我们已经发现，核（未糖基化）L0 XL 2诱导乳腺癌细胞的上皮-间充质转化（EMT，转移的第一步），并且比分泌的（N-糖基化）L0 XL 2在体外更有效地促进细胞增殖和侵袭。我们还发现分泌型LOXL 2通过核转位诱导EMT。我们的中心假设是，非糖基化LOXL 2定位于细胞核，并诱导EMT和入侵稳定蜗牛1转录因子在胺氧化酶活性依赖的方式。因此，我们希望开发抑制L0 XL 2的产生、核积累和/或活性的策略，其可以潜在地开发成用于表达核L0 XL 2的癌症的靶向疗法。在这个提议中，我们将定义LOXL 2的翻译后修饰（PTM），并解释它们在指导LOXL 2在乳腺癌转移/侵袭中的不同分子功能中的作用。成功完成所提出的研究将提供对L0 XL 2的结构-功能相关性的第一次实质性洞察。最终，这项研究的成功将为设计针对表达高水平核LOXL 2的基底样乳腺癌亚型的靶向治疗提供信息。

DESCRIPTION (provided by applicant): Lysyl oxidase-like 2 (LOXL2) is anticipated to be a promising novel therapeutic target in basal- like breast cancers, because it is highly upregulated in these cancer cells and tissues, and because inhibition of the production of LOXL2 by shRNAs or treatment with its specific antibody have been shown to retard tumor progression and metastasis/invasion in tissue culture and in animal models. LOXL2 belongs to the lysyl oxidase (LOX) family, which consists of lysine tyrosylquinone (LTQ)-dependent copper amine oxidases. LOXL2 is generally considered to catalyze ECM stiffening by its amine oxidase activity. However, intracellular functions of LOXL2 have also recently been proposed. To date, there are no structures for LOXL2 or any member of the LOX family, and very limited fundamental biochemical and biological study of LOXL2 has been conducted. We have discovered that nuclear (unglycosylated) LOXL2 induces epithelial- to-mesenchymal transition (EMT, the first step of metastasis) of breast cancer cells and promotes cell proliferation and invasion much more effectively than secreted (N-glycosylated) LOXL2 does in vitro. We also found that secreted LOXL2 undergoes nuclear-translocation to induce EMT. Our central hypothesis is that unglycosylated LOXL2 localizes to the nucleus, and there induces EMT and invasion by stabilizing Snail1 transcription factor in an amine oxidase activity-dependent fashion. Therefore, we wish to develop strategies to inhibit the production, nuclear accumulation, and/or activity of LOXL2, which could potentially be developed into a targeted therapy for cancers expressing nuclear LOXL2. In this proposal we will define the post-translational modifications (PTMs) of LOXL2 and decipher their roles in directing distinct molecular functions of LOXL2 in breast cancer metastasis/invasion. Successful completion of the proposed studies will provide the first substantial insight into the structure- function correlation of LOXL2. Ultimately, the success of this study will inform the design of targeted therapies for a subtype of basal-like breast cancers expressing elevated levels of nuclear LOXL2.