Hemochromatosis Enhances Tumor Progression <i>via</i> Upregulation of Intracellular Iron in Head and Neck Cancer

Introduction Despite improvements in treatment strategies for head and neck squamous cell carcinoma (HNSCC), outcomes have not significantly improved; highlighting the importance of identifying novel therapeutic approaches to target this disease. To address this challenge, we proceeded to evaluate the role of iron in HNSCC. Experimental Design Expression levels of iron-related genes were evaluated in HNSCC cell lines using quantitative RT-PCR. Cellular phenotypic effects were assessed using viability (MTS), clonogenic survival, BrdU, and tumor formation assays. The prognostic significance of iron-related proteins was determined using immunohistochemistry. Results In a panel of HNSCC cell lines, hemochromatosis (HFE) was one of the most overexpressed genes involved in iron regulation. In vitro knockdown of HFE in HNSCC cell lines significantly decreased hepcidin (HAMP) expression and intracellular iron level. This in turn, resulted in a significant decrease in HNSCC cell viability, clonogenicity, DNA synthesis, and Wnt signalling. These cellular changes were reversed by re-introducing iron back into HNSCC cells after HFE knockdown, indicating that iron was mediating this phenotype. Concordantly, treating HNSCC cells with an iron chelator, ciclopirox olamine (CPX), significantly reduced viability and clonogenic survival. Finally, patients with high HFE expression experienced a reduced survival compared to patients with low HFE expression. Conclusions Our data identify HFE as potentially novel prognostic marker in HNSCC that promotes tumour progression via HAMP and elevated intracellular iron levels, leading to increased cellular proliferation and tumour formation. Hence, these findings suggest that iron chelators might have a therapeutic role in HNSCC management.引言 尽管头颈部鳞状细胞癌（head and neck squamous cell carcinoma, HNSCC）的治疗策略已有所改进，但患者的预后并未得到显著改善，这凸显了研发针对该疾病的新型治疗手段的重要性。为应对这一挑战，我们开展了铁在头颈部鳞状细胞癌中作用的相关评估。 实验设计 我们采用定量逆转录聚合酶链反应（quantitative RT-PCR），对头颈部鳞状细胞癌细胞系中铁相关基因的表达水平进行了检测。通过细胞活力（MTS法）、克隆形成存活实验、溴脱氧尿苷（BrdU）掺入实验以及肿瘤形成实验，评估了细胞的表型效应。我们还利用免疫组织化学技术，明确了铁相关蛋白的预后价值。 研究结果 在一组头颈部鳞状细胞癌细胞系中，血色病蛋白基因（hemochromatosis, HFE）是铁调控通路中表达上调最为显著的基因之一。在头颈部鳞状细胞癌细胞系中体外敲低HFE，可显著下调铁调素基因（hepcidin, HAMP）的表达水平与细胞内铁含量。这一变化进而显著降低了头颈部鳞状细胞癌细胞的活力、克隆形成能力、DNA合成能力以及Wnt信号通路活性。在敲低HFE后向细胞中重新补充铁离子，可逆转上述细胞表型变化，表明铁离子介导了该表型的产生。与之相符的是，使用铁螯合剂环吡酮胺（ciclopirox olamine, CPX）处理头颈部鳞状细胞癌细胞，可显著降低细胞活力与克隆形成存活能力。最后，与HFE低表达患者相比，HFE高表达患者的总生存期更短。 研究结论 本研究数据表明，HFE可作为头颈部鳞状细胞癌潜在的新型预后标志物，其通过上调铁调素表达与细胞内铁含量促进肿瘤进展，进而增强细胞增殖能力与肿瘤形成能力。因此，本研究结果提示铁螯合剂或许可用于头颈部鳞状细胞癌的临床治疗与管理。