INHIBITION OF THE STATS SIGNALING NETWORK

我们先前报道，在SCCHN中，信号转导和转录激活因子3(STATS)是通过EGFR依赖和非EGFR依赖的途径结构性激活的。此外，STATS的结构性激活提高了SCCHN的存活率，并诱导了对EGFR抑制的抵抗，这表明STATS和STATS信号通路的组成部分，无论是单独还是与EGFR阻断一起，都可能成为重要的治疗靶点。在之前的资助期间，我们证明了激活的STATS可以选择性地与代表高亲和力血清诱导元件(HSIE)的双链“诱骗”寡核苷酸(ODN)靶向，其中STATS诱骗在体内外抑制SCCHN的生长。在NCI Raid计划的额外支持下，我们证明了STATS诱饵在非人类灵长类动物模型中是无毒的，并制造了临床级STATS诱饵。匹兹堡大学进行了一项0期临床试验，以测试STATS诱饵在人类SCCHN中的生物效应。我们进一步证明了通过靶向抑制Bc l-X{L}诱导SCCHN细胞死亡，Bc l-X是一种抗凋亡的Bc l-2家族成员，其在SCCHN中的表达受STATS调节，并与 化疗耐药。新的研究结果(见初步研究)表明，蛋白酶体在调控SCCHN细胞中STATS和Bcl2家族成员的表达和功能，以及在体内外对SCCHN的增殖和存活具有重要作用。根据我们的初步研究，我们假设STATS诱骗会降低STATS靶基因在人SCCHN中的表达。我们进一步假设，STATS和EGFR/STATS信号网络的其他组件(包括Bcl-2家族成员和蛋白酶体)的共同靶向将导致增强的抗肿瘤效果。在具体目标1中，我们将 评估STATS诱饵在调节正在进行的0期试验受试者肿瘤下游靶点方面的药效学。特异靶向2将研究STATS靶向与Bc l-2蛋白家族、蛋白酶体和EGFR抑制剂联合的抗肿瘤机制。为此，我们还将在匹兹堡大学和美国国立卫生研究院正在进行的一项合作I期试验中，评估基准磷酸化STATS/总STATS表达在调节西妥昔单抗加波特佐米治疗反应中的作用。这项试验是这些药物在SCCHN中的第一次组合。具体目标3将确定在SCCHN临床前模型中，一种口服生物可用化合物单独以及与阻断EGFR或蛋白酶体一起阻断STATS、古格列酮的抗肿瘤效果。总而言之，我们预计这些研究将使我们能够：a)评估STATS诱骗在SCCHN患者中的效果；b)优化共同靶向EGFR/STATS信号网络组件的策略；以及c)基于我们临床前模型的研究结果，测试SCCHN患者的治疗反应机制。

We prevlously reported that Signal Transducer and Activator of Transcription 3 (STATS) is constitutively activated in SCCHN via EGFR-dependent and EGFR-independent pathways. Moreover, constitutive STATS activation enhances SCCHN survival and induces resistance to EGFR inhibition, suggesting that STATS, and components of the STATS signaling pathway, may serve as important therapeutic targets either alone or in combination with EGFR blockade. In the previous funding period, we demonstrated that activated STATS could be selectively targeted with a double-stranded "decoy" oligodeoxynucleotide (ODN) representing the high affinity serum inducible element (hSIE), where the STATS decoy inhibited the growth of SCCHN in vitro and in vivo. With additional support from the NCI RAID program we demonstrated that the STATS decoy was not toxic in a non-human primate model and manufactured clinical grade STATS decoy. A phase 0 clinical trial was implemented at the University of Pittsburgh to test the biologic effects of the STATS decoy in human SCCHN. We further demonstrated induction of SCCHN cell death via targeted inhibition of Bcl-X{L}, an antiapoptotic Bcl-2 family member whose expression in SCCHN is regulated by STATS and correlates with chemotherapy resistance. New results (see Preliminary Studies) demonstrate the importance of the proteasome in regulating the expression and function of STATS and Bcl-2 family members in SCCHN cells, as well as the proliferation and survival of SCCHN in vitro and in vivo. Based on our preliminary studies, we hypothesize that STATS decoy will decrease expression of STATS target genes in human SCCHN. We further hypothesize that co-targeting of STATS and other components of the EGFR/STATS signaling network (including Bcl-2 family members and the proteasome) will result in enhanced anti-tumor effects. In Specific Aim 1 we will assess the pharmacodynamics of the STATS decoy in modulating downstream targets in the tumors from subjects enrolled in the ongoing phase 0 trial. Specific Aim 2 will investigate anti-tumor mechanisms of STATS targeting in combination with inhibitors of the Bcl-2 protein family, the proteasome, and the EGFR. In this Aim we will also evaluate the role of baseline phospho-STATS/total STATS expression in modulating response to treatment with cetuximab plus bortezomib in an ongoing collaborative phase I trial at the University of Pittsburgh and the NCI. This trial represents the first combination of these agents in SCCHN. Specific Aim 3 will determine the anti-tumor effects of an orally bioavailable compound that blocks STATS, guggulsterone, alone and in combination with blockade of EGFR or the proteasome in SCCHN preclinical models. Collectively, we expect that these studies will allow us to: a) evaluate the effects of STATS decoy in SCCHN patients, b) optimize strategies for co-targeting components of the EGFR/STATS signaling network, and c) test mechanisms of treatment response in SCCHN patients based on findings in our preclinical models.