A Role for Nucleolin in Malignant Transformation?

描述（由申请人提供）：由于我们发现核仁素是具有强抗肿瘤活性的新型适体寡核苷酸的可能靶点，我们对该蛋白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的发生，因为某些核仁素功能是更关键的转化细胞的生存比正常细胞。 已知核仁素水平升高与多种癌症的恶性进展和不良临床预后相关。 然而，由于核仁素的最佳特征功能涉及核糖体生物合成，因此通常认为这种关系仅反映了恶性细胞的较高增殖活性。由于这个原因，核仁素在癌症中的功能作用尚未得到广泛研究。这个提议的中心假设是，核仁素过度表达不仅是癌症的标志物，而且还积极促进恶性转化的过程。这一假设部分是基于一些最近的研究，已经确定了核仁素的新功能，其中许多可能会促进恶性表型的发展，生存或进展。 此外，初步的数据表明，在HeLa肿瘤细胞中的反义核仁素mRNA的表达导致减少的增殖和锚定非依赖性生长的抑制，而过度表达核仁素的HeLa细胞系表现出更积极的表型相比，野生型细胞。该提案的目的是验证核仁素过表达可在体外和体内引起正常细胞的肿瘤转化的假设，这将通过创建具有稳定高水平表达核仁素的NIH3T3衍生细胞系和产生具有前列腺靶向核仁素过表达的转基因小鼠来实现。将分析细胞系的恶性肿瘤标准特征，如形态学改变、增殖增加、锚定非依赖性生长、对凋亡刺激的敏感性降低、迁移增强和裸鼠致瘤性。将对转基因小鼠进行前列腺恶性或癌前病变的组织学检查。成功证明核仁素过表达在功能上有助于恶性转化，将为癌症研究的探索开辟新的途径，并牢固地确立核仁素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.