Tumor Suppressing Pathways in Renal Cancer

肾癌的肿瘤抑制途径

• 批准号: 8305417
• 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/8305417
• 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）是肾癌中最常见和最恶性的组织学类型，对于转移性疾病没有有效的治疗方法。其特征在于在绝大多数（60%-80%）肿瘤中von Hippel-Lindau肿瘤抑制基因（VHL）的早期丢失。microRNA（miRs）是短的非编码RNA，其与mRNA上的特定元件结合以抑制在癌症中具有调节功能的靶蛋白的翻译。我们已经发现，与正常肾脏相比，mir 204的表达在人RCC肿瘤中普遍降低，并且表达降低的程度与肿瘤分级和癌症进展密切相关。与此一致，我们发现miR 204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正调节miR 204的表达，并保护非致瘤细胞免受miR 204的细胞毒性活性。我们进一步确定了miR 204抑制巨自噬。与此一致，我们发现MAP 1 LC 3B（LC 3B）蛋白是一种宏观自噬的调节因子，是mir 204的直接靶点。我们还确定了其他几个mir 204靶点在调节巨自噬中具有潜在作用。巨自噬是细胞通过其分解细胞内细胞器以消除它们并获得营养的特定程序。因此，巨自噬作为营养物质的内部来源来支持癌细胞的存活。我们的一般假设是，RCC过程中VHL的丢失促进了mir 204的丢失和特异性靶点的去抑制，从而激活了LC 3B依赖性巨自噬，这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，并且因此当巨自噬被外源性mir 204抑制时受到合成致死，其中细胞死亡由饥饿引起。相反，VHL的存在刺激内源性mir 204的表达，并导致宏观自噬程序的抑制，使细胞对外源性mir 204的活性不敏感。为了验证这一假设，我们将明确mir 204和LC 3B依赖的巨自噬在RCC肿瘤形成中的作用（Aim 1），明确其他特异性mir 204靶点在巨自噬和肿瘤形成中的作用（Aim 2），确定导致RCC中mir 204表达降低的分子机制（Aim 3），并测定人RCC肿瘤和正常肾样品中mir 204靶标和一般自噬调节剂的水平（目的4）。影响：在这里，我们提供了一个以前未知的信号通路激活的VHL和miR 204在RCC中的损失，调节癌细胞的生存的证据。了解这一途径将为开发治疗恶性RCC的新治疗方法奠定基础。