The role of Ets family member of Fli-1 in malignancy of mammary tumors and pancreatictumors

在11例乳腺癌和4例胰腺癌中，Ets家族基因的表达水平与uPA（urokinase-type plasminogen activator）和MMP（matrix metalloproteinase）等侵袭相关基因的表达水平呈正相关。Ets-1的表达水平与肿瘤的恶性程度密切相关，已有许多报道。然而，Fli-1在实体瘤中的作用尚未得到很好的阐明。因此，我们将Fli-1的表达载体导入MCF-7人低度恶性乳腺肿瘤细胞中，以获得高水平表达Fli-1蛋白的克隆。在10%和1%胎牛血清的培养条件下，Fli-1转染子和模拟转染子的生长没有如此显著的差异。然而，Fli-1-转染子比模拟转染子更能抵抗由血清耗竭诱导的细胞凋亡。用血清D2诱导Fli-1和bcl-2的表达， 关于我们 Fli-1-转染子中的表达水平高于mock-转染子。加入JNK（Jun末端激酶）抑制剂可抑制该诱导作用，提示JNK参与了血清耗竭诱导Fli-1和bcl-2表达。Fli-1-转染子也表现出较高的抑制率的细胞凋亡的紫外线照射。由于bcl-2基因在其启动子区具有Ets结合位点，因此实体瘤中Fli-1表达增强可能在抑制细胞凋亡中起关键作用。通过使用siRNA，我们研究了其他Ets家族基因的功能作用，这些基因的表达在人类乳腺肿瘤中经常增强。用针对Ets-1、Ets-2、ER 81或E1 A-F基因的siRNA转染高度恶性的MDA-MB-231人乳腺肿瘤细胞。Ets-1的siRNA可下调MMP-1、MMP-3和MMP-9基因的表达，并抑制Ets-1的表达。针对Ets-2的siRNA下调MMP-1、MMP-3和MMP-7基因的表达。虽然siRNA的引入抑制了坏基因的表达，但没有观察到针对ER 81的MMP基因表达的变化。这些结果表明，Ets家族基因在相同的肿瘤中高度表达，通过影响单个或共同靶基因的表达参与恶性肿瘤。少

Positive correlation was found between the expression levels of several Ets family genes and invasion-related genes such as the uPA(urokinase-type plasminogen activator) and MMP(matrix metalloproteinase) genes in human malignant tumor cell lines including 11 mammary tumors and 4 pancreatic tumors. There are many reports concerning about tight correlation between the expression level of Ets-1 and tumor malignancy. However, the role of Fli-1 in solid tumors has not been elucidated well. Therefore, we introduced an expression vector of Fli-1 into MCF-7 human low-malignant mammary tumor cells to get several clones expressing high levels of Fli-1 protein. There were not so significant differences between Fli-1-transfectants and mock-transfectants in growth under culture conditions with 10% and 1% fetal bovine serum. However, Fli-1-transfectants were more resistant to apoptotic cell death induced by serum depletion than mock-transfectants. Expression of Fli-1 and bcl-2 was induced by serum d … More epletion and the expression levels were higher in Fli-1-transfectants than mock-transfectants. The induction was suppressed by adding a JNK (Jun terminal kinase) inhibitor, suggesting that JNK is in volved in induction of Fli-1 and bcl-2 expression by serum depletion. Fli-1-transfectants also showed the higher rates of inhibition of apoptosis by UV-irradiation. Since the bcl-2 gene has Ets-binding sites on its promoter region, it is likely that enhanced Fli-1 expression in solid tumors plays a critical role in inhibition of apoptosis. By using siRNA, we then examined the functional roles of other Ets family genes whose expression is often enhanced in human mammary tumors. Highly malignant MDA-MB-231 human mammary tumor cells were transfected with siRNA against the Ets-1,Ets-2,ER81 or E1A-F gene. Expression of the MMP-1,MMP-3 and MMP-9 genes was down-regulated accompanied by suppression of Ets-1 expression with siRNA against Ets-1 in the cells. Expression of the MMP-1,MMP-3 and MMP-7 genes was down-regulated with siRNA against Ets-2. No changes were observed in expression of the MMP genes with siRNA agaist ER81,although introduction of the siRNA resulted in suppression of expression of the bad gene. These results suggest that the Ets family genes highly expressed in the same tumors participate in malignancy by affecting expression of individual or common target genes. Less