Whiteman Hannah J, Weeks Mark E, Dowen Sally E, Barry Sayka, Timms John F, Lemoine Nicholas R, Crnogorac-Jurcevic Tatjana
Centre for Molecular Oncology, Institute of Cancer, Barts, UK.
Cancer Res. 2007 Sep 15;67(18):8633-42. doi: 10.1158/0008-5472.CAN-07-0545.
Up-regulation of S100P, a member of the S100 calcium-binding protein family, is an early molecular event in the development of pancreatic cancer and it is expressed at high levels in both precursor lesions and invasive cancer. To gain more insight into the molecular mechanisms underlying the functional roles of this protein, we stably overexpressed S100P in the Panc1 pancreatic cancer cell line and identified the consequent changes in global protein expression by two-dimensional difference in-gel electrophoresis. The observed changes in target proteins were confirmed by Western blot analysis and immunofluorescence, whereas their functional effect was investigated using motility and invasion assays. In this study, we have shown that overexpression of S100P led to changes in the expression levels of several cytoskeletal proteins, including cytokeratins 8, 18, and 19. We have also shown disorganization of the actin cytoskeleton network and changes in the phosphorylation status of the actin regulatory protein cofilin. Additionally, we have shown that overexpression of S100P leads to increased expression of another early pancreatic cancer marker, S100A6, as well as the aspartic protease cathepsin D, both of which are involved in cellular invasion. Functional studies showed that the increased invasive potential of S100P-overexpressing cells was at least partially due to the increase in cathepsin D expression. In summary, our data suggest that these changes could contribute to the metastatic spread of pancreatic cancer and may explain the devastating prognosis of this disease.
S100钙结合蛋白家族成员S100P的上调是胰腺癌发生过程中的早期分子事件，它在前体病变和浸润性癌中均高表达。为了更深入了解该蛋白功能作用的分子机制，我们在Panc1胰腺癌细胞系中稳定过表达S100P，并通过二维差异凝胶电泳鉴定由此引起的整体蛋白质表达变化。通过蛋白质印迹分析和免疫荧光证实了靶蛋白的观察变化，而使用迁移和侵袭试验研究了它们的功能作用。在本研究中，我们表明S100P的过表达导致几种细胞骨架蛋白表达水平的变化，包括细胞角蛋白8、18和19。我们还表明肌动蛋白细胞骨架网络紊乱以及肌动蛋白调节蛋白丝切蛋白的磷酸化状态发生变化。此外，我们表明S100P的过表达导致另一种早期胰腺癌标志物S100A6以及天冬氨酸蛋白酶组织蛋白酶D的表达增加，这两者都参与细胞侵袭。功能研究表明，S100P过表达细胞侵袭潜能的增加至少部分归因于组织蛋白酶D表达的增加。总之，我们的数据表明这些变化可能有助于胰腺癌的转移扩散，并可能解释这种疾病的不良预后。
