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

描述（由申请人提供）：整合素a3b1是一种细胞外基质受体，在许多恶性肿瘤中表达，并已被证明调节与上皮-间质转化（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，它促进肿瘤血管生成和细胞侵袭。a3b1通过mRNA转录后稳定性诱导永生化角质形成细胞（MK细胞）中的MMP-9，这种调控是在细胞永生化过程中获得的。然而，a3b1调节MMP-9 mRNA稳定性及其在肿瘤生长和进展中的作用的机制和信号通路尚不清楚。该研究的目标是通过利用一组表达a3b1（即a3野生型）和缺乏a3b1（即a3缺失）的MK变体来回答这些问题，这些变体共同代表不同的EMT阶段：(1)从新生儿表皮中分离出非永生化角质形成细胞；(2)永生化的MK细胞携带p53-null突变；(2)转化的MK细胞还表达致癌的RasV12。p53的缺失和Ras的激活是鳞状细胞和其他癌症的常见突变。该模型的初步数据表明，a3b1和MMP-9是MK细胞体内肿瘤生长所必需的，并确定了a3b1可能控制MMP-9 mRNA稳定性的候选信号通路和机制。本研究将验证以下假设：MMP-9 mRNA的表达受a3b1介导的特定信号通路控制，从而控制mRNA的稳定性，这些机制在体内控制肿瘤生长。分子、遗传和生化方法的结合将用于鉴定控制a3b1依赖性mRNA稳定性的mRNA调控元件，并阐明与a3b1介导的MMP-9 mRNA稳定性相关的特定信号通路或整合素功能。一个体内肿瘤发生模型将用于研究a3b1依赖的MMP-9调控在肿瘤生长中的作用。最后，这些观察结果的人类相关性将通过在几种人类癌细胞系中检测a3b1依赖的MMP-9调节，以及通过评估人类肿瘤标本中a3b1和MMP-9的表达来研究。公共卫生相关性：开发抗癌疗法的关键是确定肿瘤生长、进展和转移所需的分子靶点。拟议的研究将确定癌细胞中开启的促进恶性肿瘤生长和转移的新分子途径。这些途径可能是可利用的治疗靶点。

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.