Open AccessUpregulation of Nogo‐B by hypoxia inducible factor‐1 and activator protein‐1 in hepatocellular carcinoma
Author(s) -
Han Dingding,
Yang Penggao,
Qin Bo,
Ji Guoqing,
Wu Yanhua,
Yu Long,
Zhang Hong
Publication year - 2021
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/cas.14941
Subject(s) - downregulation and upregulation , hypoxia (environmental) , cancer research , angiogenesis , activator (genetics) , hepatocellular carcinoma , regulator , hypoxia inducible factors , biology , hypoxia inducible factor 1 , chemistry , microbiology and biotechnology , gene , biochemistry , organic chemistry , oxygen
Nogo‐B is an important regulator of tumor angiogenesis. Expression of Nogo‐B is remarkably upregulated in multiple tumor types, especially hepatocellular carcinoma (HCC). Here, we show the transcriptional regulation mechanisms of Nogo‐B in liver cancer. In response to hypoxia, expression of Nogo‐B significantly increased in HCC tissues and cells. The distal hypoxia‐responsive element in the promoter was essential for transcriptional activation of Nogo‐B under hypoxic conditions, which is the specific site for hypoxia inducible factor‐1α (HIF‐1α) binding. In addition, Nogo‐B expression was associated with c‐Fos expression in HCC tissues. Nogo‐B expression was induced by c‐Fos, yet inhibited by a dominant negative mutant A‐Fos. Deletion and mutation analysis of the predicted activator protein‐1 binding sites revealed that functional element mediated the induction of Nogo‐B promoter activity, which was confirmed by ChIP. These results indicate that HIF‐1α and c‐Fos induce the expression of Nogo‐B depending on tumor microenvironments, such as hypoxia and low levels of nutrients, and play a role in upregulation of Nogo‐B in tumor angiogenesis.