Tumor gene expression in vitro and in vivo

我们的生长调控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调控因子和负调控因子。目前的主要项目是研究肿瘤抑制基因家族DLC1-3及其调控的靶点。dcl1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活性负向调节Rho，但它可能编码其他活性，因为已知其他Rho- gap在癌症中不灭活。我们之前已经确定DLC1与紧张素基因家族的成员相互作用，通过DLC1的一个区域，该区域之前没有发现任何功能，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，干扰DLC1的Rho-GAP活性。我们目前正试图确定dcl1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dcl1在癌症中经常失活，因为它编码一种多功能蛋白。鉴于dcl1和紧张素之间相互作用的生物学重要性，我们探索了该基因家族（紧张素1-4）在肿瘤中的作用。研究发现，在非小细胞肺癌（NSCLC）、乳腺癌和黑色素瘤细胞系以及转基因乳腺癌小鼠模型中，Tensin-3对致瘤性起着强有力的作用。张力蛋白-3 SH2结构域具有先前描述的酪氨酸被Src磷酸化的特征，并且这种磷酸化有助于一些前致癌配体（如FAK和p130Cas）结合SH2结构域的能力。SH2结构域酪氨酸的突变降低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活性的负调控是E-cadherin负调控NSCLC肿瘤生长的新机制。在所研究的每个品系中，主要活跃的Rho GTPase家族成员Cdc42或RhoA促成了该品系的致癌特性，并受到E-cadherin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.