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

在11例乳腺肿瘤和4例胰腺肿瘤中，Ets家族基因与尿激酶型纤溶酶原激活物（uPA）、基质金属蛋白酶（MMP）等侵袭相关基因的表达水平呈正相关。关于Ets-1表达水平与肿瘤恶性程度密切相关的报道较多。然而，fl -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人乳腺低恶性肿瘤细胞中，获得了多个表达Fli-1蛋白的克隆。在10%和1%胎牛血清的培养条件下，fli -1转染物与模拟转染物的生长差异不显著。然而，fl -1转染比模拟转染更能抵抗血清缺失诱导的凋亡细胞死亡。血清d诱导Fli-1和bcl-2的表达，Fli-1转染组的表达量高于模拟转染组。添加JNK （Jun terminal kinase）抑制剂可以抑制这种诱导，提示JNK参与了通过血清缺失诱导Fli-1和bcl-2表达的过程。fl -1对紫外光照射下细胞凋亡的抑制率也较高。由于bcl-2基因的启动子区域有ets结合位点，因此在实体瘤中，Fli-1表达的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，这些基因的表达通常在人类乳腺肿瘤中增强。转染高度恶性的人乳腺肿瘤细胞MDA-MB-231，转染具有Ets-1、Ets-2、ER81或E1A-F基因的siRNA。MMP-1、MMP-3和MMP-9基因表达下调，同时siRNA抑制Ets-1在细胞中的表达。siRNA抑制Ets-2，下调MMP-1、MMP-3和MMP-7基因的表达。虽然引入siRNA抑制了坏基因ER81的表达，但在MMP基因中siRNA对ER81的表达没有变化。这些结果表明，在同一肿瘤中高表达的Ets家族基因通过影响单个或共同靶基因的表达参与恶性肿瘤的发生。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