Enhanced migration of tissue inhibitor of metalloproteinase overexpressing hepatoma cells is attributed to gelatinases: Relevance to intracellular signaling pathways

AIM: To study the effect of gelatinases (especially MMP-9)on migration of tissue inhibitor of metalloproteinase (TIMP-1) overexpressing hepatoma cells.METHODS: Wild type HepG2 cells, cells stably transfected with TIMP-1 and TIMP-1 antagonist (MMP-9-H401A, a catalytically inactive matrix metalloproteinase (MMP) which still binds and neutralizes TIMP-1) were incubated in Boyden chambers either with or without Galardin (a synthetic inhibitor of MMP-1, -2, -3, -8, -9) or a specific inhibitor of gelatinases.RESULTS: Compared to wild type HepG2 cells, the cells overexpressing TIMP-1 showed 115% migration (P＜0.05)and the cells overexpressing MMP-9-H401A showed 62% migration (P＜0.01). Galardin reduced cell migration dose dependently in all cases. The gelatinase inhibitor reduced migration in TIMP-1 overexpressing cells predominantly.Furthermore, we examined intracellular signal transduction pathways of TIMP-1-dependent HepG2 cells. TIMP-1deactivates cell signaling pathways of MMP-2 and MMP-9involving p38 mitogen-activated protein kinase. Specific blockade of the ERK pathway suppresses gelatinase expression either in the presence or absence of TIMP-1.CONCLUSION: Overexpressing functional TIMP-1-enhanced migration of HepG2-TIMP-1 cells depends on enhanced MMP-activity, especially MMP-9.

Reduced expression ofβ-catenin inhibitor Chibby in colon carcinoma cell lines

AIM: To analyse the Chibby expression and its function in colon carcinoma cell lines and colorectal carcinoma (CRC). METHODS: Chibby expression levels were investigated by quantitative RT-PCR in a panel of seven different colon carcinoma cell lines. By sequencing, we analysed mutational status of Chibby. To test whether Chibby exhibited effects onβ-catenin signalling in colon carcinoma cells, we transfected SW480 cells with Chibby expression plasmid and, subsequently, analysed activity of p-catenin and tested for alterations in cellular phenotype. In addition, we examined Chibby mRNA levels in samples of colorectal carcinomas and adjacent normal tissues by using quantitative RT-PCR and hybridised gene chips with samples from CRC and normal tissues. RESULTS: Chibby mRNA expression was strongly down-regulated in colon carcinoma cell lines in comparison to normal colon epithelial cells and no mutation in any of the examined colon carcinoma cell lines was found. Further, we could show that Chibby inhibited p-catenin activity in TOPflash assays when over-expressed in SW480 cells. Proliferation and invasion assays with Chibby transfected SW480 cells did not reveal profound differences compared to control cells. In contrast to these in vitro data, quantitative RT-PCR analyses of Chibby mRNA levels in CRC tumor samples did not show significant differences to specimens in adjacent non-cancerous tissue. Consistent with these findings, gene chips analysing tissue samples of tumors and corresponding normal tissue did not show altered Chibby expression CONCLUSION: Altered Chibby expression might be observed in vitro in different colon carcinoma cell lines. However, this finding could not be confirmed in vitro in CRC tumors, indicating that Chibby is not likely to promote CRC tumor development or progression. As Chibby is an important inhibitor ofβ-catenin signalling, our data implicate that the usability of colon carcinoma cell lines for in vitro studies analysing the Wnt/β-catenin pathway in colorectal carcinoma needs extensive verification.

Migration-associated secretion of melanoma inhibitory activity at the cell rear is supported by KCa3.1 potassium channels

恶意的黑瘤，由侵略本地生长和转移的早形成描绘了，是皮癌症的最好攻击的类型。黑瘤禁止的活动(MIA ) ，由恶意的黑瘤房间藏匿了，与房间粘附受体， integrins 伪 4 尾 1 和伪 5 尾 1，便于的房间分开和转移的支持的形成交往。在现在的学习，我们证明那 MIA 分泌物被限制到移植房间的后面的目的，当在非移居的房间 MIA 在肌动朊外皮积累时。MIA 蛋白质包括上衣蛋白质建筑群拿一条常规能分泌的小径我(COPI )- 并且上衣蛋白质建筑群 II (COPII ) 依赖者蛋白质运输到房间圆周，在它的最后的版本取决于细胞内部的 Ca2+ 离子的地方。有趣地，激活 Ca2+ 的 K+ 隧道，亚科 N，成员 4 (KCa3.1 ) ，知道在移植房间的后面的结束活跃，被发现支持 MIA 分泌物。分泌物被特定的 KCa3.1 隧道禁止者 TRAM-34 并且由隧道的主导否定的异种的表示减少。在摘要，我们阐明了到房间尾部并且也的 MIA 蛋白质的联系迁居的运输揭示了 KCa3.1 钾隧道由支持房间移植的新机制。