Moxl as a Molecular Target for Cancer Drug Discovery

活性氧(ROS)是一种细胞内信号，可通过影响细胞有丝分裂、细胞凋亡和血管生成来影响细胞生长和组织肥大。在各种生长活跃的细胞中都可以看到ROS水平的增加，包括RAS转化的细胞、各种癌症和用EGF和PDGF等生长因子处理的细胞。血管平滑肌在激动剂的作用下产生ROS，这与细胞生长和肥大有关，后者与动脉粥样硬化和高血压有关。这些细胞中ROS的来源是有争议的，线粒体和非线粒体来源都被提出。吞噬细胞通过激活产生超氧化物的呼吸爆发氧化酶(又名：NADPH氧化酶)，推测这种酶或类似的酶可以解释非吞噬细胞中ROS的产生。我们已经从分子水平克隆了p65mox1的cDNA，它是与呼吸爆发氧化酶的黄色素催化亚单位相关的新的氧化酶家族中的第一个成员。Mox1信息显示了一种独特的组织分布在非吞噬细胞中，包括结肠、前列腺和血管平滑肌。在裸鼠中，表达mox1的NIH3T3细胞产生更多的超氧化物，并表现出转化特性(病灶形成、锚定无关生长)和显著的致瘤性。本研究描述了mox1的基本生物化学和细胞生物学特征。具体地说，我们将对该酶的活性、辅因子/辅酶需求和亚细胞定位进行分子表征。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，可能还包括抑制细胞凋亡，以及对这一途径的干预，这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.