MicroRNA, sulindac, and breast cancer chemoprevention

描述(申请人提供)：流行病学、临床和临床前研究表明，非类固醇抗炎药(NSAIDs)具有显著的癌症化学预防活性。然而，与环氧合酶(COX)抑制和生理上重要的前列腺素的抑制相关的毒性限制了人类常规使用非类固醇抗炎药进行癌症化学预防。先前的研究表明，NSAIDs的抗肿瘤活性可以归因于诱导细胞凋亡的COX非依赖性机制。因此，有强有力的证据支持开发具有潜在的更安全和更有效的癌症化学预防的新药。最近的初步观察促使我们假设特定的microRNAs(MiRNAs)可以介导非甾体抗炎药舒林酸硫化物(SS)的癌症化学预防活性。MiRNAs是一种小的、非编码的RNA分子，通过其同源靶基因的翻译抑制在控制细胞生长、分化、凋亡和肿瘤发生中发挥重要作用。我们的初步结果显示，SS处理人乳腺癌细胞时，当使用2倍的截止值时，上调58和下调59 miRNAs。一种名为miR-200b的miRNA在SS和一种更活跃、非COX抑制的SS衍生物舒林酸硫化物(SSA)的治疗下显示出明显的诱导作用，我们最近发现SSA可以抑制DMBA大鼠模型的乳腺肿瘤形成。MIR-200b可以降低cGMP特异性磷酸二酯酶PDE5的表达，此前报道该酶在肿瘤细胞中过表达，并与SS的诱导凋亡活性密切相关。这些结果表明miR-200b参与了舒林酸的癌症化学预防活性的一个关键分子事件。此外，我们还发现miRNAs可以通过转录调控机制介导SS对乳腺癌细胞侵袭的抑制作用。针对这一假说的具体目的如下：1)确定miR-200b是否通过抑制PDE5介导乳腺肿瘤细胞对SS和SSA的敏感性；2)确定SS和SSA对肿瘤细胞侵袭的抑制作用是否通过抑制miRNA和NF-：B介导。这些拟议的研究有望为特定的miRNAs如何介导舒林酸的乳腺癌化学预防活性提供有价值的见解，这些研究将探索涉及抑制肿瘤细胞侵袭的新活动。 公共卫生相关性：非甾体抗炎药的抗肿瘤特性是公认的，但与环氧合酶抑制和生理上重要的前列腺素的枯竭相关的副作用限制了它们在癌症化学预防中的使用。以往的研究表明，NSAIDs抗癌作用的基础是环氧合酶不依赖的机制，这表明开发更安全、更有效的癌症预防药物可能是可行的。初步证据表明，microRNAs在NSAID舒林酸诱导的人乳腺肿瘤细胞COX非依赖性凋亡和抑制肿瘤细胞侵袭中发挥关键作用，拟议的研究有望提供有价值的见解，加速发现用于癌症化学预防的新药。

DESCRIPTION (provided by applicant): Epidemiological, clinical and preclinical studies have shown that nonsteroidal anti-inflammatory drugs (NSAIDs) possess striking cancer chemopreventive activities. However, toxicities related to cyclooxygenase (COX) inhibition and the suppression of physiologically important prostaglandins limit the regular use of NSAIDs by humans for cancer chemoprevention. Previous studies have demonstrated that the antineoplastic activities of NSAIDs can be attributed to a COX-independent mechanism that induces apoptosis. Thus, there is strong evidence to support the development of new drugs that have the potential to be safer and more efficacious for cancer chemoprevention. Recent preliminary observations have prompted us to hypothesize that specific microRNAs (miRNAs) can mediate the cancer chemopreventive activity of the NSAID sulindac sulfide (SS). MiRNAs are small, non-coding RNA molecules that play important roles in controlling cell growth, differentiation, apoptosis, and tumorigenesis through the translational repression of their cognate target genes. Our pilot results showed that SS treatment of human breast cancer cells up-regulated 58 and down-regulated 59 miRNAs when a 2-fold cutoff was used. One miRNA, termed miR-200b, exhibited a pronounced induction in response to treatment with SS and a more active, non-COX-inhibitory SS derivative, sulindac sulfide amide (SSA), which we recently found to inhibit mammary tumorigenesis in the DMBA rat model. MiR-200b can reduce the expression of the cGMP-specific phosphodiesterase PDE5, which has been previously reported to be overexpressed in tumor cells and closely associated with the apoptosis-inducing activity of SS. These results suggest that miR-200b is involved in a key molecular event that mediates the cancer chemopreventive activity of sulindac. Moreover, we found that miRNAs could mediate the suppression of breast cancer cell invasion by SS through a mechanism involving NF-:B transcriptional regulation. The specific aims to address this hypothesis are as follows: 1) determine if miR-200b mediates the sensitivity of breast tumor cells to SS and SSA by suppressing PDE5 and 2) determine if the inhibitory effects of SS and SSA on tumor cell invasion are mediated by miRNA and NF-:B inhibition. The proposed studies are anticipated to provide valuable insights into how specific miRNAs mediate the breast cancer chemopreventive activity of sulindac, and these studies will explore new activities involving the suppression of tumor cell invasion. PUBLIC HEALTH RELEVANCE: The antineoplastic properties of NSAIDs are well recognized, but side effects associated with cyclooxygenase inhibition and the depletion of physiologically important prostaglandins limit their use for cancer chemoprevention. Previous studies have shown that the basis for the anticancer properties of NSAIDs involve a cyclooxygenase-independent mechanism, which suggests that the development of safer and more efficacious drugs for preventing cancer may be feasible. Preliminary evidence suggests that microRNAs play a key role in orchestrating COX-independent apoptosis and suppression of tumor cell invasion in human breast tumor cells by the NSAID sulindac, and the proposed studies are expected to provide valuable insights that will accelerate the discovery of new drugs for cancer chemoprevention.