Integrin alpha 7: Co-regulatory mechanisms of gene expression, gene accessibility and genotoxic resistance in head and neck squamous cell carcinoma cells

头颈部鳞状细胞癌（HNSCC）是一种未满足需求的癌症。尽管在优化治疗方面做出了巨大的努力，但在过去的三十年中，局部区域控制和总体生存率保持稳定。多种遗传、表观遗传和微环境因素从根本上影响HNSCC对治疗的反应。耐药的一个关键决定因素是整合素介导的细胞外基质（ECM）相互作用，其破坏已被证明可引起对各种癌症的放疗、化疗或分子药物治疗的致敏。尽管细胞- ecm相互作用参与了核动力学过程，如基因表达和DNA修复，但仍不清楚哪些整合素特异性地共同控制基因表达和可及性，以及如何共同控制。我们自己的初步数据表明，α7整合素亚基与β1整合素亚基一起形成一个重要的层粘连蛋白结合受体，在包括HNSCC在内的许多癌症中过度表达。在HNSCC细胞中，α7整合素抑制显示出放化疗增敏潜力和组蛋白翻译后修饰的显著变化。由此推测α7整合素对基因的可及性和表达具有重要的调控作用。本研究的目的是系统地表征α7整合素依赖的调节(i)基因表达，（ii）基因可及性的全基因组、位点特异性变化，以及（iii）在不同类型的遗传毒性应激下的生存/增殖过程（包括克隆生存、细胞死亡、细胞周期、DNA修复）。为了确保更多的生理生长条件，细胞模型在三维基质中培养。结合广泛的RNA和ATAC测序数据集的生物信息学分析，我们进行了湿实验室实验，以揭示α7整合素沉默诱导的基因表达和染色质组织变化对x射线照射和各种常规化疗药物诱导的细胞存活和对基因毒性应激的抗性的功能影响。我们预计，我们的体外方法将提供初步的见解和更好的功能理解细胞- ecm相互作用（这里是α7整合素相关），这在癌症中经常被破坏，在应激反应和常规应用临床治疗方面共同调节关键核事件。

Head and neck squamous cell carcinoma (HNSCC) is a cancer of unmet need. Despite great efforts to optimize therapy, locoregional control and overall survival have remained stable over the past three decades. A variety of genetic, epigenetic, and microenvironmental factors fundamentally influence the response of HNSCC to therapy. A key determinant of resistance is integrin-mediated cell-extracellular matrix (ECM) interaction, whose disruption has been shown to elicit sensitization to radiotherapy, chemotherapy, or molecular drug therapies in various cancers. Despite the fact that cell-ECM interactions are involved in processes of nuclear homeodynamics such as gene expression and DNA repair, it remains to be unraveled which integrins specifically co-control gene expression and accessibility and how. Our own preliminary data demonstrate that the α7 integrin subunit, which together with the β1 integrin subunit forms an important laminin-binding receptor, is overexpressed in many cancers, including HNSCC. In HNSCC cells, α7 integrin inhibition shows both radiochemosensitizing potential and significant changes in histone post-translational modifications. This led us to hypothesize that α7 integrin exerts an essential regulatory function on gene accessibility and expression. The aim of this study is to systematically characterize α7 integrin-dependent regulation of (i) gene expression, (ii) genome-wide, site-specific changes in gene accessibility, and (iii) survival/proliferation processes (including clonogenic survival, cell death, cell cycling, DNA repair) upon different types of genotoxic stress in a series of human HNSCC cell models. To ensure more physiological growth conditions, cell models are cultured in a three-dimensional matrix. In combination with extensive bioinformatic analyses of RNA and ATAC sequencing datasets, wet-lab experiments are performed to uncover the functional consequences of α7 integrin silencing-induced changes in gene expression and chromatin organization on cell survival and resistance to genotoxic stress as induced by X-ray irradiation and various conventional chemotherapeutic agents. We anticipate that our in vitro approach will provide initial insights and a better functional understanding of how cell-ECM interactions (here α7 integrin-related), which are often disrupted in cancer, co-regulate critical nuclear events in terms of stress response and resistance to routinely applied clinical therapies.