Mutations in the focal adhesion targeting region of deleted in liver cancer-1 attenuate their expression and function.
Mutations in the focal adhesion targeting region of deleted in liver cancer-1 attenuate their expression and function.
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DOI：
10.1158/0008-5472.can-08-2042
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发表时间：
2008-10-01
期刊：
影响因子：
11.2
通讯作者：
Lo, Su Hao
中科院分区：
文献类型：
--
作者：
Liao, Yi-Chun;Shih, Yi-Ping;Lo, Su Hao
在肝癌中缺失的DLC-1(DLC-1)是一个RhoGAP结构域，含有肿瘤抑制因子，在各种类型的癌症中经常下调。此前，我们已经证明，DLC-1通过与Tensins的SH2(Src Homology 2)结构域结合而被招募到焦点粘连中，而焦点粘连的定位对DLC-1的S肿瘤抑制活性至关重要。为了研究粘着斑靶向区(FAT)是否可能发生突变并减弱DLC-1‘S的表达、定位和功能，我们首先将脂肪区与201到500个氨基酸残基进行了定位，然后对编码癌症患者脂肪区的cDNA和基因组DNA进行了测序。检测到了几个错义和无义突变。进一步检测所有错义突变对DLC-1‘S功能的潜在影响。T301K和S308I两个突变体对DLC-1‘S的黏附定位无明显影响，但其抑制肿瘤细胞生长的活性受到抑制。与DLC-1的RhoGAP活性对抑制肿瘤细胞生长至关重要的事实一致，这些突变体的RhoGAP活性显著降低，表明脂肪区域也包含其C末端RhoGAP结构域的调节元件。我们的研究表明，DLC-1的突变可能导致功能丧失，并有助于肿瘤的发生，并揭示了其RhoGAP活性的变构调节位点。
Deleted in liver cancer-1 (DLC-1) is a RhoGAP domain containing tumor suppressor that is often down-regulated in various cancer types. Previously, we have demonstrated that DLC-1 is recruited to focal adhesions by binding to the SH2 (Src homology 2) domains of tensins and the focal adhesion localization is critical for DLC-1's tumor suppression activity. To investigate whether mutations in the focal adhesion targeting (FAT) region might occur and attenuate DLC-1's expression, localization, and function, we have first mapped the FAT region to the amino acid residues from 201 to 500, and then sequenced cDNAs and genomic DNAs encoding the FAT region from cancer patients. Several missesne and nonsense mutations were detected. All missense mutations were further examined for the potential effect on DLC-1's function. Although these mutations did not appear to affect DLC-1's focal adhesion localization, the activities of suppressing tumor cell growth were impaired in two mutants: T301K and S308I. In consistent with the fact that the RhoGAP activity of DLC-1 is essential for inhibiting tumor cell growth, the RhoGAP activities were significantly reduced in these mutants, suggesting that the FAT region also contains a regulatory element for its C-terminal RhoGAP domain. Our studies have demonstrated that mutations in DLC-1 may lead to loss of function and contribute to the tumorigenesis, and have revealed an allosteric regulation site for its RhoGAP activity.