Promotion Of Metastatic Processes By Laminin And Laminin

层粘连蛋白和层粘连蛋白促进转移过程

• 批准号: 6966409
• 负责人: HYNDA K KLEINMAN
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DENTAL & CRANIOFACIAL RESEARCH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6966409
• 关键词: angiogenesis; basement membrane; breast neoplasms; disease /disorder model; estrogens; human tissue; laminin; melanoma; metastasis; model design /development; neoplasm /cancer; neoplastic process; phenotype; prostate neoplasms; tissue /cell culture

Studies are conducted to define the mechanisms involved in tumor growth and metastasis and to develop new animal models of human cancers. We have found that a basement membrane extract (Matrigel) when premixed with human breast and prostate tumor cells (which do not grow well in mice) promotes tumor incidence and growth. We have been able to culture new highly differentiated human tumor cell lines from the tumors grown in mice, including certain colon and prostate cell lines. Laminin, a major basement membrane component, has been found to promote the malignant phenotype of tumor cells. Laminin-adherent melanoma and colon cancer cells are more malignant than either the non-adherent cells or the parental cells. Various biologically active laminin-derived synthetic peptides have been identified. One peptide A5G27 from the alpha 5 chain blocks breast cancer growth and angiogenesis in vivo by binding in a dominant-negative manner to its receptor. We have now begun to further develop this peptide as a therapeutic (working with a peptide chemist) and to define its signaling pathways. Another peptide, LQVQLSIR, increases metastases in various tumor cell types (breast cancer, melanoma, and ovarian cancer) and binds to the receptor CD44. This is the only site on laminin found to date that promotes tumor metastasis. The receptor for this peptide has already been shown by others to be important in metastasis in a broad range of tumor cell types. We also find that CD44 is higher in melanoma cells that are adhesion-selected to this peptide, and when these peptide-adhesion-selected cells are injected into mice, more metastases are observed in the absence of added peptide. Using antibody array technology, we have identified genes regulated by this peptide. One of these genes, fibronectin, is upregulated by this peptide in all tumor cell types tested to date. We now have a better understanding of how this peptide promotes tumor metastasis. Our goal is to define the molecular mechanisms involved in tumor growth and metastases. Our approach is to (1) select for and isolate highly malignant cells, (2) define their cellular laminin receptors, (3) identify additional sequences on laminin which promote or reduce the malignant phenotype, (4) identify genes involved in malignancy, and (5) define molecules in bone responsible for prostate and breast cancer organ-specific metastases. We work with several models, including B16F10 melanoma cells, breast, prostate, and salivary gland tumor cells. We were the first to show that estrogen promotes angiogenesis. We now have begun to define the mechanisms by which estrogen promotes angiogenesis and malignancy. Using gene analysis, we have identified several genes important in the function of estrogen. We find that estrogen upregulates the enzyme heparanase which degrades the extracellular matrix. This enzyme thus increases growth factor activity by release of many growth factors from the matrix. Estrogen also down decreases the expression of a certain soluble growth factor receptor, VEGFR-1, that acts as a "decoy". Decreased expression of soluble VEGFR-1 increases the amount of VEGF (vascular endothelial cell growth factor)available. The growth factor, VEGF, promotes both angiogenesis and tumor growth by directly acting on the tumor cells. Thus, estrogen actively regulates the "angiogenic switch" in malignancy by multiple mechanisms.

研究的目的是明确肿瘤生长和转移的机制，并开发新的人类癌症动物模型。我们发现，当基底膜提取物(Matrigel)与人乳腺和前列腺肿瘤细胞(它们在小鼠体内生长不好)预混合时，会促进肿瘤的发生和生长。我们已经能够从小鼠体内生长的肿瘤中培养出新的高度分化的人类肿瘤细胞系，包括某些结肠和前列腺细胞系。层粘连蛋白是基底膜的主要成分，已被发现促进肿瘤细胞的恶性表型。层粘连蛋白粘附性黑色素瘤和结肠癌细胞比非粘附性黑色素瘤细胞或亲代细胞更恶性。目前已鉴定出多种具有生物活性的层粘连蛋白合成肽。来自α5链的一种多肽A5G27通过与其受体以显性-负性方式结合，在体内阻止乳腺癌的生长和血管生成。我们现在已经开始进一步开发这种多肽作为一种治疗手段(与多肽化学家合作)，并确定其信号通路。另一种多肽，LQVQLSIR，增加各种肿瘤细胞类型(乳腺癌、黑色素瘤和卵巢癌)的转移，并与受体CD44结合。这是迄今为止在层粘连蛋白上发现的唯一促进肿瘤转移的部位。这种多肽的受体已经被其他人证明在广泛的肿瘤细胞类型的转移中起重要作用。我们还发现，CD44在黏附选择这种肽的黑色素瘤细胞中更高，当这些黏附选择的细胞被注射到小鼠体内时，在没有添加肽的情况下观察到更多的转移。利用抗体阵列技术，我们已经鉴定了受该肽调控的基因。到目前为止，这些基因之一，纤维连接蛋白，在所有测试的肿瘤细胞类型中都被这种多肽上调。我们现在对这种多肽如何促进肿瘤转移有了更好的了解。我们的目标是确定与肿瘤生长和转移有关的分子机制。我们的方法是(1)选择和分离高度恶性的细胞，(2)定义它们的细胞层粘连蛋白受体，(3)确定促进或减少恶性表型的层粘连蛋白的额外序列，(4)确定与恶性相关的基因，以及(5)确定骨中与前列腺癌和乳腺癌器官特异性转移有关的分子。我们研究了几种模型，包括B16F10黑色素瘤细胞、乳腺、前列腺和唾液腺肿瘤细胞。 我们是第一个证明雌激素促进血管生成的人。我们现在已经开始定义雌激素促进血管生成和恶性肿瘤的机制。利用基因分析，我们已经确定了几个在雌激素功能中重要的基因。我们发现雌激素上调了乙酰肝素酶，而乙酰肝素酶则降解细胞外基质。因此，这种酶通过从基质中释放许多生长因子来增加生长因子的活性。雌激素还会降低一种特定的可溶性生长因子受体VEGFR-1的表达，而VEGFR-1则是一种“诱饵”。可溶性VEGFR-1的表达减少增加了血管内皮细胞生长因子(VEGFR-1)的含量。生长因子，血管内皮生长因子，通过直接作用于肿瘤细胞，促进血管生成和肿瘤生长。因此，雌激素通过多种机制积极调节恶性肿瘤的“血管生成开关”。