A Role for Nucleolin in Malignant Transformation?

描述（由申请人提供）：由于我们发现核蛋白是具有强抗肿瘤活性的新型适配体寡核苷酸的可能靶标，我们对这种蛋白质在癌症生物学中的作用产生了兴趣。我们已经提出，这些适体的肿瘤选择性效应之所以发生，是因为某些核蛋白功能对转化细胞的存活比正常细胞的存活更重要。已知核仁蛋白水平升高与多种癌症的恶性进展和不良临床预后有关。然而，由于核蛋白最具特征的功能涉及核糖体的生物发生，因此通常认为这种关系仅仅反映了恶性细胞更高的增殖活性。因此，核仁蛋白在癌症中的功能作用尚未得到广泛的研究。这一提议的中心假设是，核蛋白的过度表达不仅是癌症的标志，而且积极地促进了恶性转化的过程。这一假设部分基于最近的一些研究，这些研究已经确定了核仁蛋白的新功能，其中许多功能可能潜在地促进恶性表型的发展、生存或进展。此外，初步数据表明，Hela肿瘤细胞中反义核蛋白mRNA的表达导致增殖减少和锚定非依赖性生长抑制，而与野生型细胞相比，过表达核蛋白的Hela细胞系表现出更强的侵袭性表型。本课题的目的是在体外和体内验证过表达核仁蛋白可引起正常细胞肿瘤转化的假设，通过建立稳定高水平表达核仁蛋白的nih3t3衍生细胞系和产生前列腺靶向过表达核仁蛋白的转基因小鼠来实现这一假设。细胞系将被分析为恶性肿瘤的标准特征，如形态学改变，增殖增加，锚定不依赖生长，对凋亡刺激的敏感性降低，迁移增强，以及裸鼠的致瘤性。将对转基因小鼠进行前列腺癌或癌前病变组织学检查。成功证明核蛋白过表达在功能上有助于恶性转化，将为癌症研究开辟新的探索途径，并牢固地确立核蛋白作为治疗干预的新靶点。

DESCRIPTION (provided by applicant): As a result of our discovery that nucleolin is the likely target of novel aptamer oligonucleotides with strong antitumor activity, we have become interested in the role of this protein in cancer biology. We have proposed that the tumor-selective effects of these aptamers occur because certain nucleolin functions are more critical for the survival of transformed cells than for normal cells. Elevated levels of nucleolin are already known to be associated with malignant progression and poor clinical prognosis in a variety of cancers. However, because the best characterized functions of nucleolin involve ribosome biogenesis, it is commonly supposed that this relationship merely reflects the higher proliferative activity of malignant cells. For this reason, the functional role of nucleolin in cancer has not been extensively studied. The central hypothesis of this proposal is that rather than being simply a marker for cancer, nucleolin overexpression actively contributes to the process of malignant transformation. This postulate is based in part on a number of recent studies that have identified new functions for nucleolin, many of which could potentially promote the development, survival, or progression of the malignant phenotype. In addition, preliminary data indicate that expression of antisense nucleolin mRNA in Hela tumor cells leads to reduced proliferation and suppression of anchorage-independent growth, whereas HeLa cell lines overexpressing nucleolin exhibit a more aggressive phenotype compared to wild type cells. The aim of the proposal is to test the hypothesis that overexpression of nucleolin can cause neoplastic transformation of normal cells in vitro and in vivo, This will be achieved by creating NIH3T3-derived cell lines with stable high level expression of nucleolin and generating transgenic mice that have prostate-targeted overexpression of nucleolin. Cell lines will be analyzed for standard features of malignancy such as altered morphology, increased proliferation, anchorage-independent growth, decreased sensitivity to apoptotic stimuli, enhanced migration, and tumorigenicity in nude mice. Transgenic mice will be examined histologically for malignant or pre-malignant changes of the prostate. Success in demonstrating that nucleolin overexpression functionally contributes to malignant transformation would open up new avenues for exploration in cancer research and firmly establish nucleolin as a novel target for therapeutic intervention.