Erdös G, Lee Y J, Cho J M, Corry P M
William Beaumont Hospital, Department of Radiation Oncology, Royal Oak, Michigan 48073, USA.
J Cell Physiol. 1995 Aug;164(2):404-13. doi: 10.1002/jcp.1041640221.
Basic fibroblast growth factor (bFGF) has been shown to be a potent mitogen and a promoter of angiogenesis. It has been hypothesized that the expression of the bFGF gene may be induced by stress of various types. To test that hypothesis, we investigated the expression of the bFGF gene during heat treatment in adriamycin-resistant (MCF-7/ADR) and -sensitive (MCF-7) human breast carcinoma cells. Under normal growth conditions, the bFGF mRNA was detected in MCF-7/ADR cells, while it was not detectable in MCF-7 cells by Northern blot analysis. During heating at 41 degrees C, the level of bFGF mRNA increased in MCF-7/ADR cells and the message became detectable in the MCF-7 cell line. However, after continuous heating at 41 degrees C for 24 h, the bFGF mRNA level decreased to control level in MCF-7/ADR cells. Interestingly, simultaneous treatment with heat and 60 micrograms/ml H-7 (1-(isoquinolinylsulfonyl)-2-methylpiperazine, a potent PKC inhibitor) decreased the level of bFGF mRNA in MCF-7/ADR cells. These results suggest that a protein kinase, likely PKC, is involved in the transcriptional regulation of the heat-enhanced bFGF gene expression in human breast carcinoma cells. Although no heat shock element can be identified in the promoter of the bFGF gene, we observed that the AP-1 binding activity to a TPA responsive element (TRE)-like sequence in the promoter of bFGF gene was enhanced by heat, as tested by mobility shift assay. Antibody developed against the c-Jun and c-Fos proteins inhibited the AP-1 binding activity to TRE. Therefore, the AP-1 complex appears to be responsible for the heat-enhanced binding to the TRE-like motif of the bFGF gene. Furthermore, the increased AP-1 binding activity does not require new protein synthesis but activation of the preexisting c-Jun proteins.
碱性成纤维细胞生长因子（bFGF）已被证明是一种有效的促有丝分裂原和血管生成促进剂。据推测，bFGF基因的表达可能受到各种类型应激的诱导。为了验证这一假设，我们研究了阿霉素耐药（MCF-7/ADR）和敏感（MCF-7）人乳腺癌细胞在热处理过程中bFGF基因的表达。在正常生长条件下，通过Northern印迹分析在MCF-7/ADR细胞中检测到bFGF mRNA，而在MCF-7细胞中未检测到。在41℃加热期间，MCF-7/ADR细胞中bFGF mRNA水平升高，并且在MCF-7细胞系中也可检测到该信息。然而，在41℃连续加热24小时后，MCF-7/ADR细胞中bFGF mRNA水平降至对照水平。有趣的是，热与60微克/毫升H-7（1-（异喹啉磺酰基）-2-甲基哌嗪，一种有效的蛋白激酶C抑制剂）同时处理降低了MCF-7/ADR细胞中bFGF mRNA的水平。这些结果表明，一种蛋白激酶，可能是蛋白激酶C，参与了人乳腺癌细胞中热增强的bFGF基因表达的转录调控。尽管在bFGF基因的启动子中未发现热休克元件，但我们观察到，通过迁移率变动分析测试，热增强了bFGF基因启动子中与佛波酯反应元件（TRE）样序列的AP-1结合活性。针对c-Jun和c-Fos蛋白产生的抗体抑制了AP-1与TRE的结合活性。因此，AP-1复合物似乎负责热增强的与bFGF基因TRE样基序的结合。此外，增加的AP-1结合活性不需要新的蛋白质合成，而是需要预先存在的c-Jun蛋白的激活。
