The P450 Epoxygenases as Pro-Oncogenic Enzymes

描述(由申请人提供)：我们的总体目标是为肺癌治疗寻找新的、更安全、耐受性更好的抗血管生成疗法。虽然目前已经有针对肿瘤细胞或肿瘤相关血管的治疗方法用于肺癌的治疗，但它们有主要的局限性，包括：1)耐药性的产生；2)抗血管生成治疗后出现高血压、蛋白尿和肠穿孔；以及3)大多数患者仍然死于原发或转移疾病。这些局限性突显了迫切需要新的、更安全、更耐受的治疗方法来治疗这种毁灭性的疾病。这项建议侧重于两类不同但相互关联的分子对肺癌进展的影响，即细胞色素P450花生四烯酸CYP2C环氧合酶和核过氧化体增殖物激活受体α(PPARa)。我们的目标是：a)提供证据，证明尽管CYP2C是促肿瘤酶，但PPAR？作为一种新的抗肿瘤基因的功能，以及b)检验了PPAR？配体存在于它们以PPAR依赖的方式下调CYP2C表达的能力。为此，我们提供了以下证据：1)在体外和体内，内皮细胞中的CYP2C环氧合酶代谢产物(EET)是促血管生成的；2)EET水平的降低抑制了肿瘤的生长和血管生成；3)小鼠的Cyp2c44基因被破坏，或者它通过PPAR？Cyp2c44的代谢同源物--人的细胞色素P4 2C9在人非小细胞肺癌的血管系统中上调；5)两种细胞色素P4 2 C9的突变体，即细胞色素P4 2 C9*2和细胞色素P2 2 C9*3，显示出显著降低促血管生成EET的生物合成活性。在本提案中，我们将确定：a)PPAR是否？配体可以被视为一类新的更安全和耐受性更好的抗血管生成和/或抗肿瘤药物；b)Cyp2c44和PPAR的贡献？通过利用自发的和人类原位的非小细胞肺癌(NSCLC)模型来研究肺癌的发生、生长和进展；以及c)如果一组NSCLC患者的DNA中的CYP2C9*2和CYP2C9*3变异的频率的变化与NSCLC的发病率和/或进展有关，这是因为它们的EET合酶活性降低。具体地说，我们将在目标1中研究Cyp2c44在原发非小细胞肺癌发展中的作用；在目标2中，人类PPAR？以及它的配体激活与非小细胞肺癌进展的关系；以及在目的3中，非小细胞肺癌与人CYP2C9和PPAR的变异之间的关联？基因。这些研究可能作为未来临床研究的前奏，以验证PPAR的有效性？配体作为新的、有效的、更安全的抗血管生成剂用于癌症治疗。此外，它们可能导致关于P450在癌症中的作用的范式转变：从已知的在抗癌药物代谢中的作用转变为肿瘤生长/血管生成生物学中的关键参与者，从而成为抗癌药物开发的潜在有价值的靶点。

DESCRIPTION (provided by applicant): Our overall goal is to identify new, safer, and better-tolerated anti-angiogenic therapies for lung cancer treatment. While therapies targeting tumor cells or tumor-associated vasculature are currently in place for the treatment of lung cancer, they have major limitations, including: 1) the development of resistance; 2) the development of hypertension, proteinuria, and bowel perforation following anti-angiogenic therapy; and 3) most patients still die from primary or metastatic disease. These limitations underscore an urgent need for new, safer, and better-tolerated therapies for the treatment of this devastating disease. This proposal focuses on the contribution of two different, but linked, classes of molecules that can affect lung cancer progression, namely the cytochrome P450 arachidonic acid CYP2C epoxygenases and the nuclear peroxisomal proliferator activated receptor alpha (PPARa). We aim to: a) provide evidence that whereas the CYP2C are pro-tumorigenic enzymes, PPAR? functions as a new anti-tumorigenic gene, and b) test the novel hypothesis that the anti-tumorigenic activity of PPAR? ligands resides in their ability to downregulate CYP2C expression in a PPAR?-dependent fashion. To this end, we provide evidence that: 1) the endothelial CYP2C epoxygenase metabolites (EETs) are pro-angiogenic in vitro and in vivo; 2) reduction in EET levels inhibits tumor growth and angiogenesis; 3) disruption of the murine Cyp2c44 gene, or its downregulation via PPAR? activation, reduces endothelial cell function in vitro and tumor growth and vascularization in vivo; 4) the human CYP2C9, the metabolic homologue of Cyp2c44, is upregulated in the vasculature of human NSCLC; and 5) two CYP2C9 variants, namely CYP2C9*2 and CYP2C9*3, show markedly reduced pro-angiogenic EET biosynthetic activity. In this proposal we will determine: a) if PPAR? ligands can be viewed as a new class of safer and better-tolerated anti-angiogenic and/or anti-tumorigenic drugs; b) the contribution of Cyp2c44 and PPAR? to the initiation, growth, and progression of lung cancer by utilizing a spontaneous and a human orthotopic model of non small cell lung cancer (NSCLC); and c) if changes in the frequency of the CYP2C9*2 and CYP2C9*3 variants in DNAs from a cohort of NSCLC patients are associated with decreased incidence and/or progression of NSCLC due to their reduced EET synthase activity. Specifically, we will study in Aim 1 the role of Cyp2c44 in the development of primary NSCLC; in Aim 2 the contribution of human PPAR? and its ligand activation to the progression of NSCLC; and in Aim 3 associations between NSCLC and variants in human CYP2C9 and PPAR? genes. These studies may serve as prelude to future clinical studies to validate the usefulness of PPAR? ligands as new, effective, and safer anti-angiogenic agents for cancer treatment. In addition, they might lead to a paradigm shift regarding the role of P450 in cancer: from its known role in anti-cancer drug metabolism to that of a key participant in the biology of tumor growth/angiogenesis and thus a potentially valuable target for anti-cancer drug development.