HSP27: A modulator and therapeutic target of SPARC-induced glioma invasion.

描述（由申请人提供）：胶质母细胞瘤（GBM）是最恶性的脑肿瘤。患者很少在初次诊断后存活超过一年，主要是由于这些肿瘤的高度浸润性/侵袭性行为以及它们对化疗的抗性。提出的研究产生于我们的努力，以了解胶质瘤的侵袭性作为一种方法，以确定独特的治疗靶点。我们已经确定的靶点之一是分泌蛋白酸性和富含半胱氨酸（Cys），这是一种分泌到细胞外基质中的基质细胞蛋白。我们已经证明，在胶质瘤高度表达，并在体外和体内，它促进胶质瘤的侵袭。此外，我们还发现，p38 MAPK-MAPKAPK 2-HSP 27信号通路的激活，介导了细胞的迁移和侵袭。热休克蛋白27是一种小分子热休克蛋白，其功能是调节肌动蛋白细胞骨架和迁移。我们已经证明，抑制HSP 27抑制了体外PTEN缺失的胶质瘤细胞中的细胞形态、迁移和侵袭的SPARC诱导的变化。我们还证明了，在胶质母细胞瘤中通常丢失或突变的肿瘤抑制基因PTEN的再表达，抑制了SPARC诱导的体外迁移和体内侵袭。因此，我们提出，PTEN的损失，使SPARC诱导的迁移和入侵通过磷酸化热休克蛋白27。为了验证这一假设，我们提出了以下目标。具体目的1：在细胞系和人组织中，在存在或不存在PTEN的情况下，表征HSP 27的HSP 27诱导的活化。具体目标2：使用具有不同PTEN和PTEN状态的肿瘤细胞，确定单独抑制HSP 27或与放射和/或化学疗法组合是否降低体外肿瘤存活。具体目标3：使用不同PTEN状态的肿瘤细胞，确定单独抑制HSP 27或与放疗和/或化疗联合抑制HSP 27是否减少了体内SPARC诱导的肿瘤细胞侵袭和存活，并增加了动物存活。我们提出，在常见的SPARC阳性、PTEN缺失的GBM中抑制pHSP 27可以对抑制胶质瘤细胞侵袭产生显著影响，并且是胶质瘤患者的重要临床策略。 公共卫生相关性：PTEN通过激活增加HSP 27磷酸化的信号通路在体外和体内促进胶质母细胞瘤侵袭，并且PTEN是抑制体外和体内SPARC诱导的迁移的肿瘤抑制基因。我们认为，通常在胶质母细胞瘤中观察到的PTEN的缺失，促进了HSP 27的磷酸化，通常在胶质母细胞瘤中上调。我们建议这些研究将证明，pHSP 27抑制在常见的SPARC阳性，PTEN缺失的GBM可以有显着的影响，抑制胶质瘤细胞的侵袭，是一个重要的临床策略胶质瘤患者。

DESCRIPTION (provided by applicant): Glioblastomas (GBMs) are the most malignant brain tumors. Patients rarely survive more than a year after the initial diagnosis, primarily due to the highly infiltrative/invasive behavior of these tumors, and their resistance to chemotherapy. The proposed studies arise from our efforts to understand the invasive properties of gliomas as an approach to identify unique therapeutic targets. One of the targets we have identified is Secreted Protein Acidic and Rich in Cysteine (SPARC), which is a matricellular protein that is secreted into the extracellular matrix. We have demonstrated that SPARC is highly expressed in gliomas, and that it promotes glioma invasion in vitro and in vivo. Furthermore, we found that SPARC induces migration and invasion via the activation of p38 MAPK-MAPKAPK2-HSP27 signaling pathway. HSP27 is a member of the small heat shock proteins that function to modulate the actin cytoskeleton and migration. We have demonstrated that inhibition of HSP27 suppresses SPARC-induced changes in cell morphology, migration and invasion in vitro in PTEN- null glioma cells. We have also demonstrated that the re-expression of PTEN, a tumor suppressor gene commonly lost or mutated in glioblastomas, suppresses SPARC-induced migration in vitro and invasion in vivo. We therefore propose that PTEN loss enables SPARC-induced migration and invasion via phosphorylation of HSP27. To test this hypothesis we propose the following aims. SPECIFIC AIM 1: Characterize SPARC- induced activation of HSP27 in the absence or presence of PTEN in cell lines and human tissues. SPECIFIC AIM 2: Determine whether inhibition of HSP27 alone, or in combination with radiation and/or chemotherapy, reduces tumor survival in vitro using tumor cells with different SPARC and PTEN status. SPECIFIC AIM 3: Determine whether inhibition of HSP27 alone, or in combination with radiation and/or chemotherapy, reduces SPARC-induced tumor cell invasion and survival in vivo and increases animal survival, using tumor cells with different PTEN status. We propose that pHSP27 inhibition in the commonly occurring SPARC-positive, PTEN-deleted GBMs can have a significant impact on inhibiting glioma cell invasion and is an important clinical strategy for glioma patients. PUBLIC HEALTH RELEVANCE: SPARC promotes glioblastoma invasion in vitro and in vivo by activating a signaling pathway that increases phosphorylation of HSP27, and PTEN is a tumor suppressor gene that suppresses SPARC-induced migration in vitro and in vivo. We propose that the loss of PTEN, commonly observed in glioblastomas, promotes HSP27 phosphorylation by SPARC, commonly upregulated in glioblastomas. We propose that these studies will demonstrate that pHSP27 inhibition in the commonly occurring SPARC-positive, PTEN-deleted GBMs can have a significant impact on inhibiting glioma cell invasion and is an important clinical strategy for glioma patients.