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(LOXL2)有望成为治疗基底细胞样乳腺癌的新靶点，因为它在这些癌细胞和组织中高度上调，而且在组织培养和动物模型中已被证明通过shRNA抑制LOXL2的产生或用其特异性抗体治疗可以延缓肿瘤的进展和转移/侵袭。LOXL2属于赖氨酰氧化酶(LOX)家族，由赖氨酸酪氨酸醌(LTQ)依赖的铜胺氧化酶组成。LOXL2通常被认为是通过其胺氧化酶活性来催化细胞外基质硬化。然而，最近也有人提出了LOXL2的细胞内功能。到目前为止，LOXL2或LOX家族的任何成员都没有结构，对LOXL2的基础生化和生物学研究也非常有限。我们发现，在体外，核(非糖基化)LOXL2诱导乳腺癌细胞上皮向间充质转化(EMT，转移的第一步)，并比分泌型(N-糖基化)LOXL2更有效地促进细胞增殖和侵袭。我们还发现，分泌的LOXL2经历了核转位，从而诱导了EMT。我们的中心假设是未糖化的LOXL2定位于细胞核，通过以依赖于胺氧化酶活性的方式稳定Snail1转录因子来诱导EMT和侵袭。因此，我们希望开发抑制LOXL2的产生、核积累和/或活性的策略，这可能被开发成针对表达核LOXL2的癌症的靶向治疗。在这个提案中，我们将定义LOXL2的翻译后修饰(PTM)，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。拟议研究的成功完成将为LOXL2的结构-功能相关性提供第一个实质性的洞察力。最终，这项研究的成功将为针对核LOXL2水平升高的基底细胞样乳腺癌亚型的靶向治疗设计提供指导。

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.