Induction of a heat shock factor 1-dependent stress response alters the cytotoxic activity of hsp90-binding agents.
Induction of a heat shock factor 1-dependent stress response alters the cytotoxic activity of hsp90-binding agents.
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发表时间：
2000-08
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通讯作者：
R. Bagatell;G. Paine-Murrieta;C. Taylor;Elizabeth J. Pulcini;S. Akinaga;I. Benjamin;L. Whitesell
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作者：
R. Bagatell;G. Paine-Murrieta;C. Taylor;Elizabeth J. Pulcini;S. Akinaga;I. Benjamin;L. Whitesell
热休克蛋白90(Hsp90)除了在细胞应激反应中扮演经典角色外，还在调控信号转导通路中发挥关键作用，这些信号转导通路控制细胞在基础、非应激条件下的生长和存活。在过去的5年里，抗肿瘤抗生素格尔达霉素和自由基已成为公认的选择性Hsp90结合剂(HBA)，具有改变参与这些癌症相关途径的许多受体、激酶和转录因子的活性的新能力。然而，由于它们与Hsp90的相互作用，这些试剂也会诱导显著的细胞热休克反应。为了研究这种反应的机制并评估其与HBA的抗癌作用的相关性，我们验证了这些化合物可以激活包含热休克因子1(HSF1)的共同结合位点的报告结构，热休克因子1是脊椎动物热休克反应的主要转录调节因子。然后，我们使用来自HSF1基因敲除小鼠的转化成纤维细胞来表明，与传统的化疗药物不同，HBA以依赖HSF1的方式增加热休克蛋白的合成和细胞水平。与野生型小鼠的转化成纤维细胞相比，HSF1基因敲除细胞对HBA的细胞毒作用更敏感，而对阿霉素和顺铂则不敏感。与这些体外数据一致，我们发现全身给予HBA导致正常小鼠组织和人类肿瘤异种移植瘤中HSP72水平显著增加。我们的结论是，HBA是研究细胞和整个动物热休克反应调节分子机制的有用探针。此外，在这些药物的临床应用中，HBA诱导热休克反应将是一个重要的考虑因素，无论是在调节它们的细胞毒活性方面，还是在监测它们在个体患者中的生物活性方面。
In addition to its classic role in the cellular stress response, heat shock protein 90 (Hsp90) plays a critical but less well appreciated role in regulating signal transduction pathways that control cell growth and survival under basal, nonstress conditions. Over the past 5 years, the antitumor antibiotics geldanamycin and radicicol have become recognized as selective Hsp90-binding agents (HBA) with a novel ability to alter the activity of many of the receptors, kinases, and transcription factors involved in these cancer-associated pathways. As a consequence of their interaction with Hsp90, however, these agents also induce a marked cellular heat shock response. To study the mechanism of this response and assess its relevance to the anticancer action of the HBA, we verified that the compounds could activate a reporter construct containing consensus binding sites for heat shock factor 1 (HSF1), the major transcriptional regulator of the vertebrate heat shock response. We then used transformed fibroblasts derived from HSF1 knock-out mice to show that unlike conventional chemotherapeutics, HBA increased the synthesis and cellular levels of heat shock proteins in an HSF1-dependent manner. Compared with transformed fibroblasts derived from wild-type mice, HSF1 knock-out cells were significantly more sensitive to the cytotoxic effects of HBA but not to doxorubicin or cisplatin. Consistent with these in vitro data, we found that systemic administration of an HBA led to marked increases in the level of Hsp72 in both normal mouse tissues and human tumor xenografts. We conclude that HBA are useful probes for studying molecular mechanisms regulating the heat shock response both in cells and in whole animals. Moreover, induction of the heat shock response by HBA will be an important consideration in the clinical application of these drugs, both in terms of modulating their cytotoxic activity as well as monitoring their biological activity in individual patients.