Tumor gene expression in vitro and in vivo

我们的生长调节研究一直关注癌基因和肿瘤抑制基因作为正常和肿瘤生长的正和负调控基因。目前的主要项目涉及肿瘤抑制基因家族DLC1-3及其调控的靶点。DLC1在多种肿瘤中失活，但其许多方面的作用机制尚不清楚。它通过其Rho-Gap活性负性调节Rho，但它可能编码其他活动，因为其他Rho-Gap在癌症中尚不被激活。我们先前已经确定DLC1通过DLC1的一个区域与张力蛋白基因家族的成员相互作用，而该区域的功能尚未被确定，并表明这种相互作用有助于DLC1的生长抑制活性。在合作研究中，我们发现DLC1的Rho-Gap结构域与p120-RAS-GAP相互作用，并干扰DLC1的Rho-Gap活性。我们目前正试图确定DLC1的其他活性，以更好地了解其作用机制，并更充分地证实我们的假设，即DLC1在癌症中经常失活，因为它编码一种多功能蛋白质。鉴于DLC1和tensin之间相互作用的生物学重要性，我们探索了这个基因家族(tensin1-4)在肿瘤中的作用。张力蛋白-3被发现对非小细胞肺癌(NSCLC)、乳腺癌和黑色素瘤以及转基因小鼠乳腺癌模型的细胞系的致瘤性有很大的贡献。张力蛋白-3SH2结构域具有以前未描述的特征，即其酪氨酸被Src磷酸化，这种磷酸化有助于一些致癌配体，如FAK和p130Cas，与SH2结构域结合。SH2结构域中酪氨酸的突变减少了它们的结合和紧张素-3的生物活性。我们还发现，Rho GTPase家族蛋白CDC42和RhoA的活性负调节是E-钙粘素负性调节NSCLC肿瘤生长的新机制。在每个被研究的品系中，主要活跃的Rho GTP酶家族成员CDC42或RhoA对该品系的致癌特性有贡献，并受到E-钙粘附素的有效调节。

Our growth regulation research has been concerned with oncogenes and tumor suppressor genes as positive and negative regulators of normal and neoplastic growth. The main current project is concerned with a tumor suppressor gene family, DLC1-3, and the targets that it regulates. DLC1 is inactivated in a variety of tumors, but many aspects of it mechanism of action remain poorly understood. It negatively regulates Rho, via its Rho-GAP activity, but it is likely to encode other activities, as other Rho-GAPs are not known to be inactivated in cancer. We have previously determined that DLC1 interacts with members of the tensin gene family, via a region of DLC1 for which no function had been previously identified, and have shown this interaction contributes to the growth suppressor activity of DLC1. In collaborative studies, we have found that the Rho-GAP domain of DLC1 interacts with p120-Ras-GAP and interferes with the Rho-GAP activity of DLC1. We are currently trying to identify other activities of DLC1 to understand its mechanism of action better and to more fully substantiate our hypothesis that DLC1 is frequently inactivated in cancer because it encodes a multifunctional protein. Given the biological importance of the interaction between DLC1 and tensin, we have explored the role of this gene family (tensin1-4) in tumors. Tensin-3 was found to make a potent contribution to the oncogenicity of cell lines from non-small cell lung cancer (NSCLC), breast cancer, and melanoma, as well as from a transgenic mouse breast cancer model. The tensin-3 SH2 domain has the previously undescribed characteristic of its tyrosines being phosphorylated, by Src, and this phosphorylation contributes to the ability of some pro-oncogenic ligands, such as FAK and p130Cas, to bind the SH2 domain. Mutation of the the tyrosines in the SH2 domain reduces their binding and the biological activity of tensin-3. We have also identified negative regulation of the activity of Rho GTPase family proteins, Cdc42 and RhoA, as a new mechanism by which E-cadherin can negatively regulate the neoplastic growth of NSCLC lines. In each line studied, the predominantly active Rho GTPase family member Cdc42 or RhoA contributed to the oncogenic properties of the line and was potently regulated by E-cadherin.