ROLE OF SPHINGOSINE KINASE 1/SPHINGOSINE-1-PHOSPHATE PATHWAY IN COLON CARCINOGE

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。结直肠癌是美国癌症相关死亡的第二大原因。在之前的工作中，我们通过免疫组织化学和实时RT-PCR发现，在偶氮氧甲烷（AOM）诱导的啮齿动物模型和人结肠肿瘤中，人结肠癌细胞和结直肠癌组织中，鞘氨醇激酶1 (SK1)/鞘氨醇-1-磷酸（S1P）介导环氧化酶-2 (COX-2)/前列腺素E2 （PGE2）的产生比正常粘膜中过量的SK1蛋白和mRNA水平。在本学期，我们扩展了这些发现来研究我们的假设，即SK1/S1P通路可能在结肠癌发生中起关键作用。我们发现乙醇/十二烷传递系统穿透细胞内的S1P， S1P通过S1P受体和胞内机制调控COX-2启动子区域。然而，SK1过表达对琼脂糖的集落形成和胸腺小鼠的肿瘤生长没有促进作用。我们发现，与野生型小鼠相比，SK1缺乏显著减少了aom诱导的异常隐窝灶（ACF），即SK1 KO小鼠的结肠癌肿瘤前病变。这些结果有力地支持了我们的假设，SK1可能在结肠癌发生中起作用。我们目前正在用SK1 KO和野生型小鼠进行aom诱导结肠癌的长期实验。此外，我们已经在体外建立了四环素-on （tet-on）系统来培养SK1转基因小鼠。在接下来的一年里，我们将分析SK1 KO小鼠和SK1转基因小鼠的结肠癌发生情况，并确定SK1/S1P通路在结肠癌发生中的作用。我们将研究SK1/S1P与COX-2/PGE2通路之间的关系，以分析该通路在结肠癌发生中的潜在机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Colorectal cancer is the second leading cause of cancer-related deaths in the US. In the previous work, we found that sphingosine kinase 1 (SK1)/sphingosine-1-phosphate (S1P) mediates cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) production in human colon cancer cells and colorectal cancer tissues excess SK1 protein and mRNA levels as compared to normal mucosa in an azoxymethane (AOM)-induced rodent model and human colon tumors using immunohistochemistry and real time RT-PCR. In this term, we extended these findings to investigate our hypothesis that the SK1/S1P pathway may play a pivotal role in colon carcinogenesis. We found that ethanol/dodecane delivery system penetrates S1P inside the cells and S1P regulates COX-2 promoter regions through S1P receptors and intracellular mechanism. SK1 overexpression enhanced cell growth, however, did not show colony formation on agarose and tumor growth in athymic mice. We found that SK1 deficiency significantly reduced AOM-induced aberrant crypt foci (ACF), preneoplastic lesions of colon cancers, in SK1 KO mice as compared to wild type mice. These results strongly support our hypothesis and SK1 may play a role in colon carcinogenesis. We are now ongoing the long term experiment of AOM-induced colon carcinogenesis using SK1 KO and wild type mice. In addition, we have already established tetracycline-on (tet-on) system in vitro to develop SK1 transgenic mice. In the next year, we will analyze colon cancer development in SK1 KO mice and SK1 transgenic mice, and establish role of the SK1/S1P pathway in colon carcinogenesis. We will investigate relationship between SK1/S1P and COX-2/PGE2 pathways to analyze the underlying mechanisms of this pathway in colon carcinogenesis.