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）：赖氨酸氧化酶样2 （LOXL2）有望成为基底样乳腺癌的一种有前景的新治疗靶点，因为它在这些癌细胞和组织中高度上调，并且在组织培养和动物模型中，通过shrna抑制LOXL2的产生或用其特异性抗体治疗已被证明可以延缓肿瘤进展和转移/侵袭。LOXL2属于赖氨酸氧化酶（LOX）家族，由赖氨酸tyrosylquinone （LTQ）依赖性铜胺氧化酶组成。一般认为LOXL2通过其胺氧化酶活性催化ECM硬化。然而，LOXL2的细胞内功能最近也被提出。到目前为止，还没有LOXL2或LOX家族任何成员的结构，并且对LOXL2的基础生化和生物学研究非常有限。我们已经发现，核（未糖基化）LOXL2诱导乳腺癌细胞上皮向间质转化（EMT，转移的第一步），并比分泌（n -糖基化）LOXL2在体外更有效地促进细胞增殖和侵袭。我们还发现分泌的LOXL2通过核易位诱导EMT。我们的中心假设是，未糖基化的LOXL2定位于细胞核，并通过稳定Snail1转录因子以胺氧化酶活性依赖的方式诱导EMT和入侵。因此，我们希望开发抑制LOXL2的产生、核积累和/或活性的策略，这可能会成为表达核LOXL2的癌症的靶向治疗方法。在本文中，我们将定义LOXL2的翻译后修饰（PTMs），并破译它们在指导LOXL2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LOXL2结构-功能相关性的第一个实质性见解。最终，这项研究的成功将为设计针对表达核LOXL2水平升高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.