Elucidating IL-6/STAT3-mediated Phenotypic Changes in Head and Neck Cancer Stem Cells

摘要 头颈部鳞状细胞癌是一种常见且致命的恶性肿瘤。尽管取得了重大 HNSCC病理生物学的理解进展，与HNSCC相关的大量患者发病率， 治疗和高频率的肿瘤复发/转移导致不可接受的低患者存活率 生活质量差。癌症干细胞（CSC）假说试图解释观察到的异质性 癌细胞的许多恶性特征来自向干细胞的转移， 相似的特征。CSC在HNSCC中充当肿瘤起始、治疗逃避和复发的驱动因素。 铂类药物如顺铂已被证明可增强CSC分数和自我更新， 通过Bmi-1表达来确定。头部和颈部CSC依赖于血管周围小生境内的细胞串扰， 特别是对内皮细胞分泌的IL-6的影响。我们的初步数据表明，IL-6/STAT 3抑制可以防止 顺铂诱导CSC自我更新。但抑制IL-6信号传导的机制证实了这一点， 功能及其对治疗抗性和肿瘤复发的影响仍不清楚。长期 该项目的目的是研究获得和维持的分子机制， 干细胞样癌细胞表型。这项工作的总体假设是，治疗性阻断IL-10受体， 6/STAT 3通路抑制Bmi-1介导的CSC自我更新并抑制HNSCC复发。到 为了验证这一假设，我们提出了以下具体目标：1）阐明IL-6/STAT 3 - 1的机制， 介导的癌细胞群体中的表型变化，2）描述IL-6/STAT 3的实时作用 抑制和顺铂治疗对CSC增殖模式的影响，以及3）确定抑制CSC的效果 自我更新对HNSCC中常规顺铂治疗的耐药性和复发的影响。完成这些 目的，遗传学和药理学方法将用于体外和体内CSC测定，以检测 假设CSC表型由Bmi-1通过IL-6/STAT 3信号传导调节。我们会调查真实的- 使用CRISPR/Cas9报告系统测试CSC群体内的时间表型变化以验证假设 IL-6/STAT 3抑制通过减少CSC的自我更新而促进CSC的不对称细胞分裂。顺铂- 将使用耐药细胞系和患者来源的异种移植小鼠模型来检验抑制 IL-6/STAT 3信号转导将克服顺铂的逃避性耐药性并防止肿瘤复发。阐明 决定头颈癌干细胞命运的关键机制将为基于机制的 有可能提高头颈癌患者生存率和生活质量的治疗方法。

ABSTRACT Head and neck squamous cell carcinoma (HNSCC) is a frequent and deadly malignancy. Despite significant advances in the understanding of the pathobiology of HNSCC, the substantial patient morbidity associated with treatment and the high frequency of tumor recurrence/metastasis result in an unacceptably low patient survival and poor quality of life. The cancer stem cell (CSC) hypothesis attempts to explain the observed heterogeneity of cancer cells within a tumor, with many malignant features of a cancer cell deriving from a shift towards stem- like features. CSCs function as drivers of tumor initiation, therapeutic evasion, and recurrence in HNSCC. Platinum-based agents such as Cisplatin have been shown to enhance the CSC fraction and self-renewal, as determined by Bmi-1 expression. Head and neck CSCs rely on cellular crosstalk within the perivascular niche, particularly on endothelial cell-secreted IL-6. Our preliminary data showed that IL-6/STAT3 inhibition prevents Cisplatin-induced CSC self-renewal. But the mechanism through which inhibition of IL-6 signaling asserts this function and its implications on therapeutic resistance and tumor recurrence remain unclear. The long-term objective of this project is to study molecular mechanisms underlying the acquisition and maintenance of the stem-like cancer cell phenotype. The overall hypothesis of this work is that therapeutic blockade of the IL- 6/STAT3 pathway suppresses the Bmi-1-mediated CSC self-renewal and inhibits HNSCC recurrence. To test this hypothesis, we propose the following specific aims: 1) to elucidate mechanisms underlying IL-6/STAT3- mediated phenotypic changes in the cancer cell population, 2) to describe the real-time effect of IL-6/STAT3 inhibition and Cisplatin therapy on CSC proliferation patterns, and 3) to determine the effect of inhibiting CSC self-renewal on resistance to conventional Cisplatin therapy and recurrence in HNSCC. To accomplish these aims, both genetic and pharmacologic approaches will be used in CSC assays in vitro and in vivo to test the hypothesis that the CSC phenotype is regulated by Bmi-1 via IL-6/STAT3 signaling. We will investigate the real- time phenotypic changes within the CSC population using a CRISPR/Cas9 reporter system to test the hypothesis that IL-6/STAT3 inhibition promotes asymmetric cell division of CSC by decreasing their self-renewal. Cisplatin- resistant cell lines and patient-derived xenograft mouse models will be used to test the hypothesis that inhibiting IL-6/STAT3 signaling will overcome evasive resistance to Cisplatin and prevent tumor recurrence. Elucidating crucial mechanisms that define the fate of head and neck cancer stem cells will inform mechanism-based therapies that have the potential to enhance the survival and quality of life of patients with head and neck cancer.