Tumor Suppressing Pathways in Renal Cancer

肾癌的肿瘤抑制途径

• 批准号: 8398967
• 负责人: Maria F Czyzyk-Krzeska
• 金额: --
• 依托单位: CINCINNATI VA MEDICAL CENTER RESEARCH
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8398967
• 关键词: Accounting; Adult; Age-Years; Autophagocytosis; Cell Death; Cell Survival; Cells; Cessation of life; Cigarette; Conventional (Clear Cell) Renal Cell Carcinoma; Databases; Development; Disease; Elements; Epidemiology; Epithelial Cells; Event; Female; Genes; Genetic; Glucose; HK2 gene; Health; Human; Hypoxia Inducible Factor; In Vitro; Incidence; Induction of Apoptosis; Kidney; Life; Maintenance; Malignant - descriptor; Malignant Epithelial Cell; Malignant Neoplasms; Medical; Messenger RNA; Methods; MicroRNAs; Military Personnel; Modification; Molecular; Mutation; Natural Killer Cells; Nude Mice; Nutrient; Oncogenic; Organelles; Pathway interactions; Persons; Phenotype; Proteins; Proteomics; RNA Binding; Regulation; Relative (related person); Relative Risks; Renal Cell Carcinoma; Renal carcinoma; Reporting; Repression; Risk; Role; Sampling; Signal Pathway; Smoke; Smoker; Smoking; Source; Starvation; Stress; Testing; Translations; Tumor Suppressor Genes; Tumor Tissue; Untranslated RNA; VHL gene; Veterans; Xenograft Model; angiogenesis; base; cancer cell; caveolin 1; cigarette smoking; clinically relevant; cytotoxic; derepression; extracellular; male; member; non-smoker; novel therapeutic intervention; overexpression; prevent; programs; reconstitution; tumor; tumor growth; tumor progression

DESCRIPTION (provided by applicant): Renal clear-cell carcinoma (RCC) is the most prevalent and malignant histological type of kidney cancer, with no effective methods of treatment for metastatic disease. It is characterized by an early loss of the von Hippel- Lindau tumor-suppressor gene (VHL) in a large majority (60%-80%) of tumors. MicroRNAs (miRs) are short noncoding RNAs that bind to specific elements on mRNAs to repress translation of target proteins with regulatory functions in cancer. We have discovered that expression of mir204 is universally decreased in human RCC tumors, as compared with normal kidneys, and that the degree of reduced expression strongly correlates with tumor grade and cancer progression. Consistent with this, we found that miR204 has tumor- suppressing activity; it is cytotoxic to VHL(-) RCC cells in vitro and inhibits growth of tumors formed by these cells in nude mice. VHL positively regulates expression of miR204, and protects non-tumorigenic cells from cytotoxic activity of miR204. We further established that miR204 inhibits macroautophagy. Consistent with this, we found that MAP1LC3B (LC3B) protein, a regulator of macroautophagy, is a direct mir204 target. We also identified several other mir204 targets with potential roles in the regulation of macroautophagy. Macroautophagy is a specific program by which cells break down intracellular organelles to eliminate them, and also to obtain nutrients. Thus, macroautophagy serves as an internal source of nutrients to support the survival of cancer cells. Our general hypothesis is that loss of VHL during RCC promotes loss of mir204 and derepression of specific targets, thus activating LC3B-dependent macroautophagy, which gives cancer cells access to intracellular nutrients that contribute to their survival and to tumor growth. This renders RCC VHL(-) cells addicted to macroautophagic activity, and thus subject to synthetic lethality when macroautophagy is inhibited by exogenous mir204, with cell death caused by starvation. In contrast, the presence of VHL stimulates expression of endogenous mir204 and leads to suppression of the macroautophagic program, rendering the cells insensitive to the activity of exogenous mir204. To test this hypothesis, we will define the roles of mir204 and LC3B-dependent macroautophagy in RCC tumor formation (Aim 1), define the roles of other specific mir204 targets in macroautophagy and tumor formation (Aim 2); identify the molecular mechanisms leading to the decrease in mir204 expression in RCC (Aim 3); and determine levels of mir204 targets and general autophagic regulators in human RCC tumor and normal kidney samples (Aim 4). Impact: Here we provide evidence for a previously unknown signaling pathway activated by the losses of VHL and miR204 in RCC, which regulates survival of cancer cells. Understanding this pathway will lay the groundwork for the development of novel therapeutic approaches for the treatment of malignant RCC.

描述（由申请人提供）： 肾透明细胞癌（RCC）是肾癌最普遍，最恶性的组织学类型，没有有效的转移性疾病治疗方法。它的特征是在绝大多数（60％-80％）的肿瘤中早期丧失von Hippellindau肿瘤抑制基因（VHL）。 MicroRNA（miR）是与MRNA上特定元素结合的简短非编码RNA，以抑制具有调节功能在癌症中的靶蛋白的翻译。我们已经发现，与正常肾脏相比，人类RCC肿瘤的MiR204的表达普遍降低，并且表达降低的程度与肿瘤等级和癌症进展密切相关。与此一致，我们发现miR204具有肿瘤抑制活性。它在体外对VHL（ - ）RCC细胞具有细胞毒性，并抑制这些细胞在裸鼠中形成的肿瘤的生长。 VHL积极调节miR204的表达，并保护非氧化细胞免受miR204的细胞毒性活性。我们进一步确定miR204抑制了大噬细胞。与此相一致，我们发现MAP1LC3B（LC3B）蛋白是大量自噬的调节剂，是直接的miR204靶标。我们还确定了其他几个MiR204靶标，在大型噬菌体的调节中具有潜在的作用。大量噬菌体是一个特定的程序，细胞通过该程序分解细胞内细胞器以消除它们并获得营养。因此，大自噬细胞是支持癌细胞存活的内部养分。我们的总体假设是，RCC期间VHL的损失促进了MiR204的损失和特定靶标的压抑，从而激活了LC3B依赖性的大量自噬，这使癌细胞获得了有助于其存活和肿瘤生长的细胞内营养。这使RCC VHL（ - ）细胞上瘾对大型噬菌学活性，因此当大量自噬被外源性miR204抑制时会受到合成的致死性，而细胞死亡是由饥饿引起的。相反，VHL的存在刺激了内源性miR204的表达，并导致抑制大型噬菌学程序，从而使细胞对外源性miR204活性不敏感。为了检验这一假设，我们将定义MiR204和LC3B依赖性大型噬菌体在RCC肿瘤形成中的作用（AIM 1），定义了其他特定的MiR204靶标在大型噬菌体和肿瘤形成中的作用（AIM 2）；确定导致RCC中miR204表达降低的分子机制（AIM 3）；并确定人RCC肿瘤和正常肾脏样品中MIR204靶标和一般自噬调节剂的水平（AIM 4）。影响：在这里，我们为RCC中VHL和MiR204的损失激活了先前未知的信号通路，该信号通路调节了癌细胞的存活。了解这一途径将为开发新型治疗方法的治疗奠定基础。