Role of Claudin-1 in Colon Cancer

描述（由申请人提供）： 结直肠癌（CRC）是退伍军人武装部队人员癌症相关死亡的主要原因之一，每年退伍军人事务管理和治疗约175，000名结直肠癌患者[1]。虽然在疾病的筛查/诊断方面取得了重大进展，但治疗选择仍然只有适度的成功，主要包括手术切除和化疗。重要的是，疾病进展和转移仍然是VA-CRC患者发病率和死亡率的主要原因。因此，迫切需要有希望抑制CRC进展的新疗法。我们的研究是朝着这个方向迈出的重要一步。值得注意的是，我们和其他实验室的大量工作已经证实，claudin-1的表达在CRC中以阶段特异性方式高度上调，并且与CRC生长和进展有因果关系。现在，我们使用一种新的小鼠模型，在Notch信号传导和结肠细胞成熟/杯状细胞分化/Muc-2表达的调节中，显示了claudin-1的新作用。我们进一步证明了通过APCmin和claudin-1转基因小鼠之间的杂交产生的后代中结肠肿瘤负荷（肿瘤发生率和生长）和侵袭性的多倍增加。在我们继续的研究中，我们现在已经产生了证据表明Notch和Wnt信号转导以claudin-1依赖性方式协同作用，可能通过调节癌症干细胞来增加APCmin/Cl-1小鼠中的CRC。综上所述，我们的假设是增加的密蛋白-1表达诱导Notch-超活化以失调正常结肠分化和稳态，并因此通过Notch和Wnt信号传导之间的协同作用诱导对CRC生长和进展的易感性。为了验证我们的假设，我们提出了以下具体目标：具体目标1。确定claudin-1表达调节Notch信号传导以调节结肠肿瘤发生。在这里，我们将：a）确定Notch信号传导调节APC min/Cl-1小鼠中增加的肿瘤发生; B）确定粘膜炎症是否有助于结肠肿瘤发生和/或侵袭性的紧密连接蛋白-1依赖性增加; c）确定Notch活化的紧密连接蛋白-1依赖性调节的潜在机制。具体目标2。确定Notch与Wnt/β-连环蛋白信号传导协同调节结肠肿瘤发生中的claudin-1依赖性增加。在此，我们将确定：a）抑制Wnt/B-连环蛋白信号传导对APC min/Cl-1小鼠结肠肿瘤发生的影响。B）Wnt/B-连环蛋白信号传导中的密蛋白-1依赖性增加取决于Notch-活化并检查潜在的机制; c）结肠癌患者中密蛋白-1表达是否与Notch和b-连环蛋白/Wnt-活化相关及其与癌症侵袭性的潜在关联。具体目标3。探讨APC/Wnt信号通路在结肠Claudin-1表达调控中的作用。在这里，我们将：a）检查APC（WT）-Smad 4轴在Claudin-1表达调节中的作用; B）确定APC和Smad 4之间在Claudin-1转录调节中的串扰的细节。我们的短期目标是更好地了解claudin-1表达失调如何调节结肠癌细胞形成肿瘤和进一步发展的能力。我们的长期目标是开发claudin-1特异性抑制剂，可以特异性地递送到结肠癌细胞，从而创造一种无毒并抑制疾病进展的抗CRC药物。我们相信这种治疗干预可以显着提高患有结直肠癌的美国退伍军人的生存率和生活质量。

DESCRIPTION (provided by applicant): Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths in the Veterans armed forces personnel and each year Veterans affairs manages and treats ~175,000 colorectal cancer patients [1]. Although, significant advances are made in the screening/diagnosis of the disease, treatment options remain only moderately successful and primarily include surgical resection and chemotherapy. Importantly, disease progression and metastasis remain the prime cause of the morbidity and mortality among VA-CRC patients. Thus, new therapies with the promise to inhibit CRC progression are urgently needed. Our studies are an important step in that direction. Notably, extensive work from our and other laboratories has confirmed that expression of claudin-1 is highly upregulated in CRC in a stage-specific manner, and is causally associated with CRC growth and progression. Now, using a novel mouse model of intestine-specific claudin-1 overexpression, we show novel role of claudin-1 in the regulation of Notch-signaling and colonocyte maturation/goblet cell differentiation/Muc-2 expression. We further demonstrate multi-fold increase in colonic tumor burden (tumor incidence and growth) and aggressiveness in the offspring generated through the cross between APCmin and claudin-1 transgenic mice. In our continued study, we have now generated evidence that Notch- and Wnt-signaling synergize in claudin-1-dependent manner to augment CRC in APCmin/Cl-1 mice, possibly through the regulation of cancer stem cells. Taken together, our hypothesis is that increased claudin-1 expression induces Notch-hyper activation to dysregulate normal colonic differentiation and homeostasis, and thus induces susceptibility to CRC growth & progression through the synergy between Notch and Wnt- signaling. To test our hypothesis, we propose following specific aims: Specific Aim 1. Determine that claudin-1 expression modulates Notch-signaling to regulate colon tumorigenesis. Here we will: a) determine that Notch-signaling regulates increased tumorigenesis in APCmin/Cl-1 mice; b) determine whether mucosal inflammation contributes to Claudin-1-dependent increase in colon tumorigenesis and/or aggressiveness; c) determine the mechanism/s underlying Claudin-1-dependent regulation of Notch-activation. Specific Aim 2. To determine that Notch synergizes with Wnt/b-catenin signaling to regulate claudin-1- dependent increase in colon tumorigenesis. Here, we will determine: a) the impact of inhibition of Wnt/b- catenin-signaling on colon tumorigenesis in APCmin/Cl-1 mice.; b) that claudin-1-dependent increase in Wnt/b- catenin signaling depends upon Notch-activation and to examine the underlying mechanism/s; c) whether claudin-1 expression correlates with Notch and b-catenin/Wnt-activation in colon cancer patients and its potential association with the aggressiveness of cancer. Specific Aim 3. To investigate the role of APC/ Wnt-signaling in the regulation of colonic Claudin-1 expression. Here, we will: a) examine the role of APC (WT)-Smad4 axis in the regulation of Claudin-1 expression; b) determine the details of the cross-talk between APC and Smad4 in transcriptional regulation of Claudin-1. Our short term goal is to better understand how dysregulation of claudin-1 expression modulates the ability of colon cancer cells to form tumor and further progression. Our long term goal is to develop claudin-1-specific inhibitors that can be delivered specifically to the colon cancer cells and thus to create an anti-CRC drug that is not toxic and inhibits disease progression. We believe such therapeutic interventions can significantly increase survival and quality of life US Veterans who are suffering from colorectal cancer.