MDA-7/IL-24: Therapy of Malignant Glioma

多形性胶质母细胞瘤(GBM)是最致命和最难治疗的肿瘤之一；密集的放化疗组合不能治愈，对患者的生存只产生轻微的影响。对新的替代治疗方式有重大需求。局部治疗，如手术切除和立体定向放射外科，已取得部分成功，而全身治疗无效。我们实验室以前的研究表明，无论是以病毒形式(Ad.mda-7)还是以纯化的融合蛋白(GST-MDA-7)形式给药，新型白介素MDA-7/IL-24都能抑制GBM细胞的生长。 低浓度的丙二醛-7(约0.5 nM)抑制生长而不杀死细胞，而高浓度的丙二醛-7(&gt；20 nM)抑制生长并促进细胞死亡。此外，低水平的MDA-7增强了在二维和三维培养的已建立和原代GBM细胞的体外辐射敏感性，以及在体内生长为肿瘤时的辐射敏感性。在原代星形胶质细胞中没有观察到这些抗增殖和细胞毒作用。MDA-7抑制GBM细胞增殖和与辐射相互作用杀死GBM细胞的分子机制尚不清楚。对于项目2中的研究，我们假设MDA-7作为一种 细胞因子不仅促进细胞死亡，而且还调节线粒体！使肿瘤细胞对辐射有更强的反应。具体目的1将确定MDA-7对ERK1/2、ERK5、PI3K/AKT、JNK和P38通路的激活的浓度依赖性作用；控制已建立的GBM细胞(U251)和未建立的GBM细胞(GBM6表达EGFR VIII，GBM14缺乏PTEN功能)的增殖和存活的途径。平行研究将确定辐射暴露对丙二醛-7诱导的通路激活的影响。丙二醛-7增强辐射敏感性的机制(S)将被确定，可能是通过改变活性氧的产生和bcl2/bh3家族成员的表达。特指目标2将确定PIS激酶和MEK1/2/5抑制剂联合处理GBM细胞增强MDA-7对细胞杀伤的分子机制。具体目标3将确定在已存在的原发人类GBM6肿瘤中注射Ad.mda-7或GST-MDA-7是否能减少肿瘤生长并增强体内的放射敏感性。

Glioblastoma multiforme (GBM) is one of the most lethal and difficult tumors to treat; intensive combinations of radio- and chemotherapy are no curative and yield only a modest impact on patient survival. There is a major need for new alternative therapeutic modalities. Local treatments such as surgical resection and stereotactic radiosurgery, have been partially successful, whereas systemic therapy has been ineffective. Previous studies by our laboratories have shown that the novel interleukin MDA-7 / IL-24 administered either as a virus (Ad.mda-7) or as a purified fusion protein (GST-MDA-7), suppressed the growth of GBM cells. Low concentrations of MDA-7 (approximately 0.5 nM) suppressed growth without killing cells whereas higher levels of MDA-7 (> 20 nM) suppressed growth and enhanced cell death. In addition, low levels of MDA-7 enhanced the in vitro radiosensitivity of established and primary GBM cells cultured in 2- and 3-dimensions, and when grown as tumors in vivo. These anti-proliferative and cytotoxic effects were not observed in primary astrocytes. The molecular mechanisms by which MDA-7 inhibits GBM cell proliferation and interacts with radiation to kill GBM cells are unknown. For the studies in Project 2, we hypothesize that MDA-7 acting as a cytokine both promotes cell death and, in addition, modulates mitochondria! function so that tumor cells are more radio-responsive. Specific aim 1 will determine the concentration-dependent effect of MDA-7 on the activation of the ERK1/2, ERK5, PI3K/AKT, JNK and P38 pathways; pathways that control the proliferation and survival of established GBM cells (U251) and non-established GBM cells (GBM6 expressing EGFR VIII, GBM14 lacking PTEN function. Parallel studies will determine the impact of radiation exposure on MDA-7-induced pathway activation. The mechahism(s) by which MDA-7 enhances radiosensitivity; potentially by altering reactive oxygen species generation and the expression of BCL-2 / BH3 family members, will be determined. Specific aim 2 will determine the molecular mechanisms by which combined treatment of GBM cells with PIS kinase and MEK1/2/5 inhibitors enhance cell killing by MDA-7. Specific aim 3 will determine whether infusion of Ad.mda-7 or infusion of GST-MDA-7, into a pre-existing primary human GBM6 tumor, reduces tumor growth and enhances radiosensitivity in vivo.