肿瘤相关性巨噬细胞依赖HIF-1α调节肺癌细胞干性的作用机制

Lung cancer remains the leading cause of cancer death. Cancer stem cell (CSC) theory has gained significant recognition as crucial factor driving cancer development. While evidence suggests tumor associated macrophages (TAM) in lung cancer microenvironment promote tumor growth and metastasis. However, it's not clear that whether TAM mediates tumor progression through induction of stemness feature of lung cancer. Our preliminary data suggests TAM may increase CSC-phenotype of lung cancer cells, therefore this study aims to investigate the role of TAM in regulating stemness characteristics in lung cancer. First, we plan to evaluate CSC frequency, tumorigenecity and expression of CSC related transcriptional factors in lung cancer in the presence or absence of TAM. Second, activation phenotype of TAM within lung cancer environment will also be studied. Given HIF-1αcreated hypoxia is vital in CSC maintenance and TAM in lung cancer microenvironment express higher HIF-1α, alterations of stemness of lung cancer will be analyzed after TAM derived HIF-1αis blocked by RNAi approach or small molecule inhibitor. In addition, the potential effect of Wnt/β-Catenin signal pathway in LCSC stemness maintenance will also be tested. In summary, this study would elucidate the role of TAM in stemness regulation of lung cancer cells .It provides a novel rationale of targeting HIF-1αexpressing TAM for lung cancer immune therapy.

肺癌是当前我国发病率最高的恶性肿瘤，预后差。肿瘤相关性巨噬细胞（tumor associated macrophages ，TAM）和肿瘤干细胞（cancer stem cell，CSC）均对肺癌的发生发展起重要促进作用。研究表明TAM可激活肿瘤细胞的CSC表型，提示TAM与肿瘤细胞的干性关系密切，而TAM在肺癌细胞干性调控中的作用仍属未知。我们的初步研究发现肺癌微环境中的TAM不仅高表达干性维持相关因子- - 缺氧诱导因子（hypoxia-inducible factor ，HIF）-1α且激活肺癌细胞的CSC表型, 提示TAM可能通过HIF-1α参与肺癌细胞的干性调节。在本项目中，我们将系统分析TAM对肺癌细胞干性的调控作用，再进一步通过体内体外研究阐明HIF-1α及其相关信号转导通路在这一调控作用中的角色及其细胞分子机制，以期为肺癌的免疫治疗提供新的靶点。

肿瘤微环境对于肺癌的发生发展至关重要。肿瘤相关性巨噬细胞和肺癌细胞的相互作用是其恶性进展的重要原因之一。巨噬细胞是否可通过调节肺癌干细胞的干性来促进其发生发展不得而知。我们研究表明TAM与肿瘤细胞共培养后不仅可促进其增值。同时在mRNA水平共培养后可上调肺癌细胞的Sox2、Nanog等干细胞相关标志物，流式细胞术提示共培养后另一干性指标ALDH活性升高，均提示TAM与肿瘤细胞的干性关系密切。同培养后的巨噬细胞分泌HIF－1alpha，TGF－beta，IL6等促肿瘤生长因子提高。在我们抑制Stat3等干性相关通路后，以上提示干性的各类指标均下调，且巨噬细胞表达各类促肿瘤生长因子也相应减少。因此，本研究提示巨噬细胞通过分泌TGF－beta等促肿瘤生长因子经Stat3等干细胞相关通路激活肺癌细胞的干性表达，可能为未来设计肺癌治疗靶向药物提供新的思路。