Moxl as a Molecular Target for Cancer Drug Discovery

活性氧（ROS）与细胞内信号有关，并可能通过影响有丝分裂、凋亡和血管生成来影响细胞生长和组织肥大。在多种活跃生长的细胞中，包括ras转化细胞、多种癌症和经生长因子（如EGF和PDGF）处理的细胞中，均可见ROS水平升高。血管平滑肌对激动剂产生ROS，这与动脉粥样硬化和高血压中涉及的细胞生长和肥大有关。这些细胞中活性氧的来源是有争议的，已经提出了线粒体和非线粒体来源。吞噬细胞通过激活产生超氧化物的呼吸爆发氧化酶（又称NADPH氧化酶）产生高水平的ROS，据推测，这种氧化酶或类似的酶在非吞噬细胞中产生ROS。我们分子克隆了p65mox1的cDNA， p65mox1是一个新型氧化酶家族的第一个成员，该家族与呼吸爆发氧化酶的催化黄细胞色素亚基有关。mox1信息在非吞噬细胞中具有独特的组织分布，包括结肠、前列腺和血管平滑肌。在胸腺小鼠中，表达mox1的NIH 3T3细胞产生增加的超氧化物，并表现出改变的特性（病灶形成、不依赖锚定生长）和显著的致瘤性。本文研究了mox1的基本生物化学和细胞生物学特性。具体来说，我们将进行酶活性的分子表征，它的辅因子/辅酶需求，以及它的亚细胞位置。我们将研究将p65mox1与细胞生长和致瘤性联系起来的下游信号通路。我们还将研究p65mox1的更广泛的生物学效应，包括有丝分裂、血管生成和细胞凋亡的抑制，以及这一途径的干预措施，这些干预措施可能与治疗人类增生性疾病（如癌症）有关。

Reactive oxygen species (ROS) are implicated as intracellular signals and may affect cell growth and tissue hypertrophy by affecting mitogenesis, apoptosis and perhaps angiogenesis. Increased levels of ROS are seen in a variety of actively growing cells including Ras-transformed cells, a variety of cancers and cells treated with growth factors such as EGF and PDGF. Vascular smooth muscle generates ROS in response to agonists, and this has been linked to cell growth and hypertrophy which is implicated in atherosclerosis and hypertension. The origin of ROS in these cells is controversial and both mitochondrial and non-mitochondrial sources have been proposed. Phagocytes generate high levels of ROS by activating the superoxide-generating respiratory burst oxidase (a.k.a. NADPH oxidase), and it has been speculated that either this oxidase or a similar enzyme accounts for ROS generation in non-phagocytic cells. We have molecularly cloned the cDNA for p65mox1, the first member of a family of novel oxidases which are related to the catalytic flavocytochrome subunit of the respiratory burst oxidase. The mox1 message shows a unique tissue distribution in non phagocytic cells including colon, prostate and vascular smooth muscle. NIH 3T3 cells expressing mox1 generate increased superoxide and show transformed properties (focus formation, anchorage-independent growth) and marked tumorigenicity in athymic mice. This study characterizes the basic biochemistry and cell biology of mox1. Specifically, we will carry out a molecular characterization of the enzyme activity, its cofactor/coenzyme requirements, and its subcellular location. We will investigate the downstream signaling pathways that link p65mox1 to cell growth and tumorigenicity. We will also investigate the wider spectrum of biological effects of p65mox1, which include mitogenesis, angiogenesis and perhaps inhibition of apoptosis, and interventions in this pathway which may be relevant to treatment of human hyperproliferative disorders such as cancer.