Inhibiting extracellular Hsp90 to reduce breast cancer metastasis

 描述（由申请人提供）：寻找靶向乳腺癌侵袭（转移的第一步）而不影响正常组织的药物是一个重要的未达到的目标。目前高度关注的一种蛋白质靶标是分子伴侣Hsp 90，其在癌症进展和转移以及正常细胞功能中起作用。 热休克蛋白90抑制剂如ganetespib目前正在临床试验中，但它们可能具有严重的副作用，因为许多蛋白质需要热休克蛋白90来激活。 我们引入了在癌细胞外抑制Hsp 90的概念来解决这个问题。 我的实验室首次发现，细胞外热休克蛋白90（eHsp 90）是由癌细胞释放的，它通过激活基质金属蛋白酶-2在癌症侵袭中起作用。 从那时起，我们和其他人已经表明，eHsp 90激活细胞外介质中的许多前蛋白，以增强侵袭，包括赖氨酰氧化酶样2（LOXL 2），它重塑细胞外基质，并与癌症密切相关。我们还表明，eHsp 90是通过外泌体从细胞中释放出来的，在新的数据中，我们表明抑制Hsp 90会减少外泌体的释放和摄取，这与侵袭期间的肿瘤通讯有关。抑制eHsp 90可以防止这种情况，从而减少侵袭和转移。我们的长期目标是实现eHsp 90抑制剂治疗乳腺癌的临床试验。最近，我们发现STA-12-7191（ganetespib的不渗透衍生物）抑制癌细胞运动性，但对正常细胞的毒性低5倍。这些发现表明 特异性抑制eHsp 90将通过防止LOXL 2的活化和外来体释放、减少侵袭而不具有抑制Hsp 90的细胞内功能的破坏作用而有益于癌症治疗。我们将在以下目标中测试这一假设：1。测试L0 XL 2是否是真正的eHsp 90客户端，从而提供用于体内eHsp 90抑制的生物标志物; 2.确定eHsp 90如何在外泌体运输中起作用，并表明这是亲侵入性的; 3.使用临床注释的患者血清和新的ELISA诊断测试血清eHsp 90水平与转移性乳腺癌之间的关联;和4.在人乳腺-骨异种移植模型中测试eHsp 90在乳腺癌转移中的作用。我们汇集了一个杰出的合作团队，包括eHsp 90的先驱PI，开发ganetespib和STA-12-7191的Ying博士以及Hsp 90（Neckers），乳腺癌生物标志物（Seewaldt和Luo）和转移动物模型（Kuperwasser）的专家。这项研究意义重大，因为它将验证eHsp 90作为治疗转移性乳腺癌的重要药物靶点，并暗示它参与两个重要的促侵袭过程：基于外泌体的肿瘤通讯和LOXL 2的ECM重塑。重要的是，这项研究可能会导致一种药物，可以抑制这些过程，副作用比目前在人体试验中的Hsp 90抑制剂更少。此外，本发明还提供了一种方法， 考虑到eHsp 90在发病机制中的多重作用，它将影响其他癌症和其他疾病。这项工作是创新的，因为它测试了一种新的外泌体运输机制，并引入了一种新的化合物来抑制eHsp 90并测试其在癌症中的益处。

 DESCRIPTION (provided by applicant): Finding drugs that target breast cancer invasion (the first step in metastasis) without affecting normal tissue is an important unmet goal. One protein target of high current interest is the molecular chaperone Hsp90, which functions in cancer progression and metastasis as well as normal cell function. Hsp90 inhibitors such as ganetespib are currently in clinical trials, however they may have serious side effects based on the many proteins that require Hsp90 for activation. We introduced the concept of inhibiting Hsp90 outside of cancer cells to circumvent this problem. My lab first showed that extracellular Hsp90 (eHsp90) is released by cancer cells and that it acts in cancer invasion by activation of Matrix Metalloproteinase-2. Since then, we and others have shown that eHsp90 activates many pro-proteins in the extracellular media to enhance invasion including Lysyl Oxidase-like 2 (LOXL2), which remodels the extracellular matrix and is well implicated in cancer. We also showed that eHsp90 is released from cells via exosomes and, in new data, we show that inhibiting Hsp90 reduces exosome release and uptake, which has been implicated in tumor communication during invasion. Inhibiting eHsp90 may prevent this thus reducing invasion and metastasis. Our long-term goal is to achieve a clinical trial for an eHsp90 inhibitor for breast cancer. Recently we showed that STA-12-7191 (an impermeant derivative of ganetespib) inhibits cancer cell motility but is 5-fold less toxic to normal cells. These findings suggest that specifically inhibiting eHsp90 will benefit cancer treatment by preventing activation of LOXL2 and exosome release, reducing invasion without the damaging effects of inhibition of Hsp90's intracellular functions. We will test this hypothesis in the following Aims: 1. Test if LOXL2 is a bona fide eHsp90 client thereby providing a biomarker for eHsp90 inhibition in vivo; 2. Determine how eHsp90 acts in exosome trafficking and show this is pro-invasive; 3. Test the association between serum eHsp90 levels and metastatic breast cancer using clinically annotated patient sera and a novel ELISA diagnostic; and 4. Test the role of eHsp90 in breast cancer metastasis in human breast-to-bone xenograft model. We bring together an outstanding collaborative team including the PI who pioneered eHsp90, Dr. Ying who developed ganetespib and STA-12-7191 and experts in Hsp90 (Neckers), breast cancer biomarkers (Seewaldt and Luo) and metastasis animal models (Kuperwasser). This study is significant because it would validate eHsp90 as an important drug target for treating metastatic breast cancer and implicate it in two important pro-invasive processes: exosome-based tumor communication and ECM remodeling by LOXL2. Importantly, this study could lead to a drug that would inhibit these processes with fewer side effects than the Hsp90 inhibitors currently in human trials. In addition, it would impact other cancers and other diseases given eHsp90's multiple roles in pathogenesis. The work is innovative because it tests a novel mechanism for exosome trafficking and introduces a novel compound to inhibit eHsp90 and testing its benefit in cancer.