Regulation of MMP-9 mRNA stability and tumor growth by alpha3 beta1 integrin

描述（由申请人提供）：整合素a3 b1是一种细胞外基质受体，在许多恶性肿瘤中表达，并已显示可调节与上皮-间充质转化（EMT）相关的细胞表型，如细胞增殖、存活和侵袭。基质金属蛋白酶MMP-9的表达也与恶性肿瘤的生长有关，其中它促进肿瘤血管生成和细胞侵袭。a3 b1通过转录后mRNA稳定性诱导永生化角质形成细胞（MK细胞）中的MMP-9，并且这种调节在细胞永生化期间获得。然而，a3 b1调节MMP-9 mRNA稳定性的机制和信号通路及其在肿瘤生长和进展中的作用尚不清楚。所提出的研究的目标是通过利用一组a3 b1表达（即a3野生型）和a3 b1缺陷（即，a3-无效）MK变体，其共同代表不同的EMT阶段：（1）从新生儿表皮分离非永生化的角质形成细胞;（2）永生化的MK细胞具有p53-无效突变;（2）转化的MK细胞另外表达致癌的RasV 12。p53缺失和致癌Ras激活是鳞状细胞癌和其他癌中常见的突变。该模型的初步数据表明，a3 b1和MMP-9是MK细胞体内肿瘤生长所必需的，并确定了a3 b1可能控制MMP-9 mRNA稳定性的候选信号通路和机制。拟议的研究将测试的假设，MMP-9 mRNA的表达是由特定的a3 b1介导的信号通路，控制mRNA的稳定性，这些机制控制肿瘤生长在体内控制。分子、遗传和生物化学方法的组合将用于鉴定控制a3 b1依赖性mRNA稳定性的mRNA调控元件，并阐明参与a3 b1介导的MMP-9 mRNA稳定性的特定信号通路或整合素功能。将使用体内肿瘤发生模型来研究MMP-9的a3 b1依赖性调节对肿瘤生长的作用。最后，将通过在几种人类癌细胞系中检测MMP-9的a3 b1依赖性调节，并通过评估a3 b1和MMP-9在人类肿瘤标本中的表达来研究这些观察结果的人类相关性。公共卫生相关性：开发抗癌疗法的关键是鉴定肿瘤生长、进展和转移所需的分子靶标。拟议的研究将确定在癌细胞中打开以促进恶性肿瘤生长和转移的新分子途径。这些途径可作为治疗靶点。

DESCRIPTION (provided by applicant): Integrin a3b1 is an extracellular matrix receptor that is expressed in many malignant tumors and has been shown to regulate cellular phenotypes associated with epithelial-to-mesenchymal transition (EMT), such as cell proliferation, survival, and invasion. Expression of matrix metalloproteinase MMP-9 is also linked to malignant tumor growth, where it promotes tumor angiogenesis and cell invasion. a3b1 induces MMP-9 in immortalized keratinocytes (MK cells) through post-transcriptional mRNA stability, and this regulation is acquired during cellular immortalization. However, the mechanisms and signaling pathways whereby a3b1 regulates MMP-9 mRNA stability and their roles in tumor growth and progression are unknown. The goal of the proposed research is to answer these questions by exploiting a panel of a3b1-expressing (i.e. a3 wild type) and a3b1- deficient (i.e., a3-null) MK variants that collectively represent different EMT stages: (1) non-immortalized keratinocytes are isolated from neonatal epidermis; (2) immortalized MK cells harbor a p53-null mutation; (2) transformed MK cells additionally express oncogenic RasV12. Loss of p53 and oncogenic Ras activation are common mutations in squamous cell and other carcinomas. Preliminary data from this model indicate that a3b1 and MMP-9 are required for in vivo tumor growth of MK cells, and identify candidate signaling pathways and mechanisms whereby a3b1 may control MMP-9 mRNA stability. The proposed studies will test the hypotheses that MMP-9 mRNA expression is controlled by specific a3b1-mediated signaling pathways that control mRNA stability, and that these mechanisms control tumor growth in vivo. A combination of molecular, genetic, and biochemical approaches will be used to identify mRNA regulatory elements that control a3b1- dependent mRNA stability, and to elucidate specific signaling pathways or integrin functions that are involved in a3b1-mediated MMP-9 mRNA stability. An in vivo tumorigenesis model will be used to investigate the role of a3b1-dependent regulation of MMP-9 for tumor growth. Finally, the human relevance of these observations will be investigated by testing for a3b1-dependent regulation of MMP-9 in several human carcinoma lines, and by assessing expression of a3b1 and MMP-9 in human tumor specimens. PUBLIC HEALTH RELEVANCE: A key to the development of anti-cancer therapies is the identification of molecular targets that are required for tumor growth, progression, and metastasis. The proposed studies will identify novel molecular pathways that are turned on in cancer cells to promote malignant tumor growth and metastasis. These pathways may be exploitable as therapeutic targets.