Hochhauser Daniel, Kotecha Minal, O'hare Caroline, Morris Peter J, Hartley Janet M, Taherbhai Zarmeen, Harris Dorothy, Forni Claudia, Mantovani Roberto, Lee Moses, Hartley John A
Department of Oncology, Royal Free and University College Medical School, University College London, 91 Riding House Street, London W1W 7BS, United Kingdom.
Mol Cancer Ther. 2007 Jan;6(1):346-54. doi: 10.1158/1535-7163.MCT-06-0503.
Topoisomerase IIalpha (topo IIalpha) is an important target for several chemotherapeutic agents, including etoposide and doxorubicin. Confluent cells express low levels of topo IIalpha and are resistant to etoposide treatment. Repression of transcription in confluent cells is mediated by binding of the transcription factor NF-Y to inverted CCAAT motifs within the topo IIalpha promoter. To block the repressive binding of NF-Y, a polyamide (JH-37) was designed to bind to the flanking regions of selected CCAAT sites within the topo IIalpha promoter. Electrophoretic mobility shift assays and DNase I footprinting assays showed occupancy of the inverted CCAAT sites by JH-37. Chromatin immunoprecipitation assays confirmed in vivo inhibition of NF-Y binding to the topo IIalpha promoter. Following incubation of confluent NIH3T3 cells with JH-37, increased expression of topo IIalpha mRNA and protein was detectable. This correlated both with increased DNA double-strand breaks as shown by comet assay and decreased cell viability following exposure to etoposide. Polyamides can modulate gene expression and chemosensitivity of cancer cells.
拓扑异构酶IIα（topo IIα）是包括依托泊苷和阿霉素在内的多种化疗药物的重要靶点。汇合细胞表达低水平的topo IIα，并且对依托泊苷治疗具有抗性。汇合细胞中转录的抑制是由转录因子NF-Y与topo IIα启动子内反向CCAAT基序的结合介导的。为了阻断NF-Y的抑制性结合，设计了一种聚酰胺（JH-37）以结合topo IIα启动子内选定CCAAT位点的侧翼区域。电泳迁移率变动分析和DNase I足迹分析表明JH-37占据了反向CCAAT位点。染色质免疫沉淀分析证实了体内对NF-Y与topo IIα启动子结合的抑制。在用JH-37孵育汇合的NIH3T3细胞后，可检测到topo IIα mRNA和蛋白的表达增加。这与彗星试验所示的DNA双链断裂增加以及暴露于依托泊苷后细胞活力降低均相关。聚酰胺可以调节癌细胞的基因表达和化学敏感性。
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