Regulation of Claudin-1 mediated Colon Tumor Progression and Metastasis

描述(申请人提供)：细胞-细胞连接蛋白表达和/或细胞定位的改变是肿瘤发生，特别是转移和侵袭的标志。黏附连接蛋白在癌症中的作用已被广泛研究；然而，对紧密连接蛋白的作用了解较少。Claudins是一个新近发现的蛋白质家族，对紧密连接(TJ)的结构和功能是不可或缺的。最近的研究表明，在肿瘤发生过程中，Claudins的表达/细胞定位发生了不同的和组织特异性的变化；然而，因果关系尚未建立。我们最近报道，在结肠癌中，claudin-1的表达以肿瘤阶段特异性的方式增加(正常、癌和转移)，并且主要定位于细胞核和细胞质。最重要的是，利用claudin-1在非转移性和高转移性结肠癌细胞中的过度表达或基因抑制，我们证明了claudin-1在肿瘤进展和转移调节中的作用。在这项拨款提案中，我们将我们之前的研究扩展到确定claudin-1作为肿瘤促进剂和转移的潜在作用的机制。由于转移是肿瘤相关死亡的主要原因，我们选择首先以失巢凋亡作为研究模型来确定信号和分子机制，这可能适用于体内转移和侵袭的模型。此外，我们还建议研究claudin-1在结肠转移样本和细胞系中新的核定位的机制及其与转移的相关性。此外，我们还建议通过APC的调节来确定claudin-1在结肠癌中的特异性表达/细胞定位的调节。值得注意的是，APC突变是结直肠癌的一个标志。这项工作旨在为claudin-1介导的调控机制及其调控提供洞察力，并将有助于未来开发治疗试剂或小分子抑制剂以测试其临床意义。

DESCRIPTION (provided by applicant): Changes in the expression and/or cellular localization of cell-cell junction proteins is a hallmark of tumorigenesis, especially metastasis and invasion. The role of adherent junction proteins has been studied extensively in cancer; however, the role of tight junction proteins is less well understood. Claudins are a family of recently identified proteins that are integral to the structure and function of tight junctions (TJs). Recent studies have shown differential and tissue specific changes in expression/cellular localization for claudins during tumorigenesis; however, a cause and effect relationship has yet to be established. We have recently reported that in colon cancer, claudin-1 expression is increased in a tumor stage specific manner (normal>carcinoma>metastasis), and is predominantly localized to cell nucleus and cytoplasm. Most importantly, using over-expression or genetic inhibition of claudin-1 in non-metastatic & highly metastatic colon cancer cells, we demonstrated a role of claudin-1 in the regulation of tumor progression and metastasis. In this grant proposal, we have extended our previous studies to the determination of mechanism underlying the role of claudin-1 as a tumor promoter and metastasis. Since, metastasis is the principal cause of tumor related deaths, we have elected to first define the signaling and molecular mechanisms using anoikis as the model of study, which could potentially be applicable to in vivo model of metastasis and invasion. In addition, we have proposed to examine the mechanisms underlying the novel nuclear localization of claudin-1 in colon metastasis samples and cell lines and its correlation with metastasis. Also, we have proposed to determine the regulation of colon cancer specific expression/cellular localization of claudin-1 through the regulation of APC. It is noteworthy that APC mutation is a hallmark of colorectal cancer. The work described in this proposal is intended to provide insight for the mechanism of claudin-1 mediated regulation as well as its regulation and would help in future studies for development of therapeutic reagents or small molecule inhibitors to test their clinical relevance.