TARGETING SPLEEN TYROSINE KINASE IN CHEMORESISTANT OVARIAN CARCINOMA

描述（由申请人提供）：本提案的目的是解决癌症研究中的一个关键问题-耐药性的分子基础。最终目标是改善诊断为晚期癌症的患者的治疗反应和总体预后。我们将使用卵巢高级别浆液性癌（HGSC）作为疾病模型，因为它是女性中最具侵袭性的癌症类型之一。HGSC对化疗药物耐药性的发展是实现长期缓解的主要挑战。为了实现这一目标，我们采用了蛋白质组学方法来比较来自相同患者的原发性和复发性/化疗后HGSC组织之间的全局蛋白质组。在复发性HGSC中鉴定的优先表达的蛋白质中，非受体酪氨酸激酶脾酪氨酸激酶（SYK）引起极大兴趣。SYK是一种非受体蛋白酪氨酸激酶，参与介导多种细胞信号传导事件， 反应，包括增殖、细胞运动、分化和吞噬作用。小的化合物抑制剂如Fostamatinib（AstraZeneca）和R112（Rigel）是可用的，并已用于类风湿性关节炎、自身免疫性疾病和造血系统恶性肿瘤患者的晚期临床试验。在我们的初步研究中，我们能够表明，与来自相同HGSC患者的相应原发性肿瘤相比，化疗后复发性肿瘤中的总SYK和p-SYK（活性形式）水平增加。我们发现SYK抑制与紫杉醇协同抑制体外肿瘤细胞生长。SYK抑制剂和紫杉醇的组合在小鼠肿瘤异种移植模型中具有最大的抗肿瘤作用。我们已经应用定量蛋白质组学分析，SILAC（稳定同位素标记/与细胞培养中的氨基酸），以确定潜在的SYK底物和发现微管相关蛋白（MAP）和微管蛋白，可能有助于异常微管动力学在紫杉醇耐药癌细胞。基于我们的初步结果，我们假设SYK激活磷酸化MAP和微管蛋白，导致微管动力学增加，从而拮抗紫杉醇的作用。SYK抑制剂可以降低MAP或微管蛋白的磷酸化，使化疗耐药细胞对紫杉醇治疗敏感。因此，靶向SYK信号传导可以逆转紫杉醇抗性并增强HGSC中的紫杉醇作用。在化学抗性癌症中靶向SYK的概念是新颖且高度转化的。如果我们的临床前研究结果是有希望的，SYK药物将值得在临床试验中进一步评估。

DESCRIPTION (provided by applicant): The objective of this proposal is to address a critical issue in cancer research - the molecular basis of drug resistance. The ultimate goal is to improve treatment response and overall prognosis in patients diagnosed with advanced cancer. We will use ovarian high-grade serous carcinoma (HGSC) as the disease model because it is one of the most aggressive cancer types in women. The development of resistance to chemotherapeutic reagents in HGSC represents a major challenge to achieving long term remission. To accomplish this goal, we have employed a proteomic method to compare global proteomes between primary and recurrent/post-chemotherapy HGSC tissues from the same patients. Among the preferentially expressed proteins identified in recurrent HGSCs, a non-receptor tyrosine kinase, Spleen Tyrosine Kinase (SYK), is of great interest. SYK is a non-receptor protein tyrosine kinase that is involved in signaling events that mediate diverse cellular responses, including proliferation, cell movement, differentiation, and phagocytosis. Small compound inhibitors such as Fostamatinib (AstraZeneca) and R112 (Rigel) are available and have been used in late phase clinical trials for patients with rheumatoid arthritis, auto-immune diseases, and hematopoietic malignancy. In our preliminary studies, we were able to show that total SYK and p-SYK (the active form) levels increased in recurrent post-chemotherapy tumors as compared to corresponding primary tumors from the same HGSC patients. We found that SYK inhibition cooperated synergistically with paclitaxel to inhibit tumor cell growth in vitro. A combination of SYK inhibitor and paclitaxel had the greatest anti-tumor effect in a mouse tumor xenograft model. We have applied quantitative proteomic analysis, SILAC (stable isotope labeling by/with amino acids in cell culture), to identify potential SYK substrates and discovered microtubule-associated proteins (MAPs) and tubulins that may contribute to aberrant microtubule dynamics in paclitaxel-resistant cancer cells. Based on our preliminary results, we hypothesize that SYK activation phosphorylates MAPs and tubulin, resulting in increased microtubule dynamics and thus antagonizing the effects of paclitaxel. SYK inhibitors could decrease the phosphorylation in MAPs or tubulin, rendering chemoresistant cells susceptible to paclitaxel treatment. Thus, targeting SYK signaling may reverse paclitaxel resistance and potentiate paclitaxel effects in HGSCs. The concept of targeting SYK in chemoresistant cancers is novel and highly translational. If our preclinical results turn out to be promising, SYK inhibitrs would warrant further evaluation in clinical trials.