Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, Gifu, Japan.
J Cell Biochem. 2021 Aug;122(8):777-786. doi: 10.1002/jcb.29911. Epub 2021 Feb 28.
Lysyl oxidase (LOX) is a copper-containing enzyme and its overexpression in tumor tissues promote tumor metastasis through the crosslinking of extracellular matrix. Our previous report demonstrated that LOX expression is significantly increased in human leukemic THP-1 cell-derived M2-like macrophages, and histone modification plays a key role in its induction. However, the rigorous mechanism of LOX regulation remains unclear. In this study, we investigated the role of functional transcription factors, hypoxia-inducible factor 1α (HIF1α), signal transducer and activator of transcription 3 (STAT3) and forkhead box O1 (FOXO1) in LOX regulation in M2-like macrophages. HIF1α expression was significantly increased in M2-like macrophages, and HIF1α inhibitor, TX402, suppressed LOX induction. The significant STAT3 activation was also observed in M2-like macrophages. Additionally, LOX induction was canceled in the presence of STAT3 inhibitor, S3I-201, suggesting that HIF1α and STAT3 pathways play a critical role in LOX induction. On the other hand, our ChIP results clearly indicated that the enrichment of FOXO1 within the lox promoter region was dramatically decreased in M2-like macrophages. In this context, knockdown of FOXO1 further enhanced LOX induction. LOX induction and HIF1α binding to the lox promoter region were suppressed in FOXO1-overexpressed cells, suggesting that the FOXO1 binding to the lox promoter region counteracted HIF1α binding to that region. Overall, the present data suggested that both of HIF1α and STAT3 were required for LOX induction in M2-like macrophages, and loss of FOXO1 within the lox promoter region facilitated HIF1α binding to that region which promoted LOX induction.
赖氨酰氧化酶（LOX）是一种含铜酶，其在肿瘤组织中的过表达通过细胞外基质的交联促进肿瘤转移。我们之前的报告表明，LOX 表达在人白血病 THP-1 细胞来源的 M2 样巨噬细胞中显著增加，组蛋白修饰在其诱导中起关键作用。然而，LOX 调节的严格机制尚不清楚。在这项研究中，我们研究了功能转录因子缺氧诱导因子 1α（HIF1α）、信号转导和转录激活因子 3（STAT3）和叉头框 O1（FOXO1）在 M2 样巨噬细胞中 LOX 调节中的作用。HIF1α 在 M2 样巨噬细胞中的表达显著增加，HIF1α 抑制剂 TX402 抑制 LOX 诱导。在 M2 样巨噬细胞中也观察到 STAT3 的显著激活。此外，在存在 STAT3 抑制剂 S3I-201 的情况下，LOX 诱导被取消，表明 HIF1α 和 STAT3 途径在 LOX 诱导中起关键作用。另一方面，我们的 ChIP 结果清楚地表明，在 M2 样巨噬细胞中，FOXO1 在内 LOX 启动子区域的富集显著减少。在这种情况下，FOXO1 的敲低进一步增强了 LOX 的诱导。FOXO1 过表达细胞中 LOX 诱导和 HIF1α 结合到 lox 启动子区域被抑制，表明 FOXO1 结合到 lox 启动子区域抵消了 HIF1α 结合到该区域。总的来说，这些数据表明，HIF1α 和 STAT3 都需要在 M2 样巨噬细胞中诱导 LOX，并且在 lox 启动子区域内缺失 FOXO1 促进了 HIF1α 结合到该区域，从而促进 LOX 诱导。
