Tumor Suppressing Pathways in Renal Cancer

肾癌的肿瘤抑制途径

• 批准号: 8696822
• 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/8696822
• 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）是肾癌中最常见和恶性的组织学类型，目前没有有效的治疗转移性疾病的方法。其特征是大多数 (60%-80%) 肿瘤中 von Hippel-Lindau 肿瘤抑制基因 (VHL) 早期丢失。 MicroRNA (miR) 是短非编码 RNA，可与 mRNA 上的特定元件结合，抑制在癌症中具有调节功能的靶蛋白的翻译。我们发现，与正常肾脏相比，人类肾细胞癌肿瘤中 mir204 的表达普遍降低，并且表达降低的程度与肿瘤分级和癌症进展密切相关。与此相一致的是，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体内形成的肿瘤的生长。 VHL 正向调节 miR204 的表达，并保护非致瘤细胞免受 miR204 的细胞毒活性影响。我们进一步确定 miR204 抑制巨自噬。与此一致的是，我们发现 MAP1LC3B (LC3B) 蛋白（巨自噬的调节因子）是 mir204 的直接靶点。我们还确定了其他几个在巨自噬调节中具有潜在作用的 mir204 靶点。巨自噬是细胞分解细胞内细胞器以消除它们并获取营养的一种特定程序。因此，巨自噬作为营养物质的内部来源来支持癌细胞的生存。我们的一般假设是，RCC 期间 VHL 的丢失会促进 mir204 的丢失和特定靶标的去抑制，从而激活 LC3B 依赖性巨自噬，从而使癌细胞能够获得有助于其生存和肿瘤生长的细胞内营养物质。这使得RCC VHL(-)细胞对巨自噬活性上瘾，因此当巨自噬被外源性mir204抑制时会遭受合成致死，细胞因饥饿而死亡。相反，VHL 的存在会刺激内源性 mir204 的表达，并导致巨自噬程序受到抑制，从而使细胞对外源性 mir204 的活性不敏感。为了检验这一假设，我们将定义 mir204 和 LC3B 依赖性巨自噬在 RCC 肿瘤形成中的作用（目标 1），定义其他特定 mir204 靶标在巨自噬和肿瘤形成中的作用（目标 2）；确定导致 RCC 中 mir204 表达减少的分子机制（目标 3）；确定人类 RCC 肿瘤和正常肾脏样本中 mir204 靶标和一般自噬调节因子的水平（目标 4）。影响：在这里，我们为 RCC 中 VHL 和 miR204 缺失激活的先前未知的信号通路提供了证据，该信号通路调节癌细胞的存活。了解这一途径将为开发治疗恶性肾细胞癌的新治疗方法奠定基础。