Role of iNOS, Nitric Oxide & Arginase in Statin-Mediated Toxicity in Cancer Cells

项目摘要/摘要。 长期目标：他汀类药物选择性抑制羟甲基戊二酰辅酶A(HMG-CoA) 还原酶导致胆固醇生物合成减少。几种天然和合成的他汀类药物 人淋巴母细胞、骨髓瘤和乳腺癌细胞的凋亡。这种效果直接与他们的 抑制HMG CoA还原酶的能力，而不是通过抑制HMG CoA还原酶来阻止异戊二烯基化小GTP酶的合成 角鲨烯，胆固醇的直接前体。这一建议是基于他汀类药物引起的 通过增加诱导型一氧化氮的表达增加对乳腺癌细胞的细胞毒作用 一氧化氮合酶(INOS)、一氧化氮(NO)和/或精氨酸酶表达降低。他汀类药物介导的细胞死亡是 部分逆转由1400W，一种更特异的iNOS抑制剂(NOS II)和甲氧戊酸，立即 乙酰辅酶A/HMG-辅酶A还原酶反应的代谢产物。甲伐他汀补充剂可抑制他汀类药物 诱导型一氧化氮合酶和一氧化氮，恢复精氨酸酶表达。氟伐他汀剂量依赖性抑制乳腺 在活体动物模型中肿瘤的发展。有待检验的假设是：(I)他汀类药物刺激乳房中的一氧化氮 负责其促凋亡、杀瘤和抗增殖作用的癌细胞，(Ii)他汀类药物抑制 通过抑制RhoA信号在乳腺癌细胞中的精氨酸酶表达和活性，以及 补充sepiapterin(诱导型一氧化氮合酶辅助因子)和生育三烯醇增强他汀类药物诱导的杀瘤作用 对乳腺癌细胞和大鼠模型的影响。具体目标：(1)评估各种他汀类药物的效果 (亲脂性和亲水性)和生育三烯醇对乳腺癌细胞增殖和凋亡的影响，(Ii)确定 他汀类药物单独及海风蝶呤和精氨酸酶对细胞诱导型一氧化氮合酶和一氧化氮生成的影响 抑制物，(Iii)确定RhoA在他汀类药物介导的NO生成、精氨酸酶表达、核因子B抑制中的作用 以及对乳腺癌细胞的抗增殖作用，(Iv)建立化学预防大鼠模型，并对其进行评价。 他汀类药物单独或与生育三烯醇或七叶蝶呤合用的有效性。方法：我们将使用MCF- 7和MDA-MB-231细胞，以及化学诱导的乳腺癌大鼠模型。高效液相色谱技术将用于 检测和定量他汀类药物处理的细胞中NO的生成。磁共振成像(MRI)将是 用于在大鼠模型中评估乳腺癌治疗的反应。意义：最近的研究表明 他汀类药物可以预防包括乳腺癌在内的各种癌症。然而，分子 他汀类药物诱导乳腺癌细胞死亡的机制尚不清楚。这项建议将推进我们的 他汀类药物单独及联合应用对化疗预防和治疗能力的影响 自然生成的生育三烯醇。新颖性：总体目标是阐明 他汀类药物在乳腺癌细胞中发挥抗增殖/促凋亡作用。生育三烯醇的使用 协同增强他汀类药物对乳腺癌细胞和乳腺癌动物的化学预防作用 模式是创新的。核磁共振将用于监测乳腺癌在大鼠模型中的化学预防作用。项目叙述/相关性。 他汀类药物是最广泛使用的处方药之一。最近的研究表明，亲脂性 他汀类药物对绝经后妇女可能是有益的。研究还表明，当他汀类药物与 其他营养素，作为抗癌药物变得更有效。乳腺癌是#年的主要死亡原因。 女人。因此，了解他汀类药物杀死乳房的机制(S)既及时又重要 并探讨他汀类药物作为化学预防药物临床应用的可能性。

PROJECT SUMMARY / ABSTRACT. Long-term goal: Statins selectively inhibit the enzyme hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase leading to decreased cholesterol biosynthesis. Several natural and synthetic statins enhanced apoptosis in human lymphoblastoid, myeloma and breast cancer cells. This effect was directly related to their ability to inhibit HMG CoA reductase, which blocks the synthesis of isoprenylated small GTPases, and not by squalene, an immediate precursor of cholesterol. This proposal is based on the discovery that statins cause increased cytotoxicity to breast cancer cells through either increased expression of inducible nitric oxide synthase (iNOS) and nitric oxide (¿NO) and/or decreased arginase expression. Statin-mediated cell death was partially reversed by 1400W, a more specific inhibitor of iNOS (NOS II), and by mevalonate, an immediate metabolic product of acetyl CoA/HMG-CoA reductase reaction. Mevalonate supplementation inhibited statin- induced iNOS and ¿NO and restored arginase expression. Fluvastatin dose-dependently inhibited mammary tumor development in an in vivo animal model. Hypotheses to be tested are: (i) statins stimulate ¿NO in breast cancer cells that is responsible for their proapoptotic, tumoricidal and antiproliferative effects, (ii) statins inhibit arginase expression and activity through inhibition of RhoA signaling in breast cancer cells, and (iii) supplementation with sepiapterin (iNOS co-factor) and tocotrienols potentiates statin-induced tumoricidal effects in breast cancer cells and in a rat model. Specific aims: (i) Assess the effects of various statins (lipophilic and hydrophilic) and tocotrienols on breast cancer cell proliferation, and apoptosis, (ii) Determine the induction of iNOS and ¿NO formation in cells treated with statins alone and with sepiapterin and arginase inhibitors, (iii) Define the role of RhoA in statin-mediated ¿NO generation, arginase expression, Nf¿B inhibition and antiproliferative effects in breast cancer cells, (iv) Establish a chemopreventive rat model, and evaluate the effectiveness of statins alone and in combination with ¿-tocotrienol or sepiapterin. Methods: We will use MCF- 7 and MDA-MB-231 cells and a chemically-induced breast cancer rat model. HPLC techniques will be used to detect and quantitate ¿NO formation in cells treated with statins. Magnetic resonance imaging (MRI) will be used to assess the response to breast cancer therapy in a rat model. Significance: Recent research suggests that statins may prevent various types of cancers including breast cancer. However, the molecular mechanisms by which statins induce breast cancer cell death remain unknown. This proposal will advance our understanding of the chemopreventive and chemotherapeutic ability of statins, alone and in combination with naturally-occurring tocotrienols. Novelty: The overall goal is to elucidate the molecular mechanism by which statins exert antiproliferative/proapoptotic effects in breast cancer cells. The use of tocotrienols to synergistically enhance chemopreventive efficacy of statin in breast cancer cells and breast cancer animal model is innovative. MRI will be used to monitor chemopreventive effects of breast cancer in a rat model. PROJECT NARRATIVE / RELEVANCE. Statins are one of the most widely prescribed group of drugs. Recent studies suggest that lipophilic statins may be beneficial for postmenopausal women. Studies also suggest that statins, when combined with other nutrients, become more potent as anticancer drugs. Breast cancer is the leading cause of death in women. Thus, it is both timely and important to understand the mechanism(s) by which statins kill breast cancer cells and to explore the possibility for clinical implementation of statins as chemopreventive drugs.