ΗΙF1α, EGR1 and SP1 co-regulate the erythropoietin receptor expression under hypoxia: An essential role in the growth of non-small cell lung cancer cells

Tianhong Su, Pi Liu, Xinyu Ti, Shouzhen Wu, Xiaochang Xue, Zenglu Wang, Elhardji Dioum, Qiuyang Zhang

Research output: Contribution to journalArticle

Abstract

Background: Overexpression of erythropoietin (EPO) and EPO receptor (EPO-R) is associated with poor prognosis in non-small-cell lung carcinoma (NSCLC). Hypoxia, a potent EPO inducer, is a major stimulating factor in the growth of solid tumors. However, how EPO-R expression is regulated under hypoxia is largely unknown. Methods: The role of EPO-R in NSCLC cell proliferation was assessed by RNA interference in vitro. Luciferase reporter assays were performed to map the promoter elements involved in the EPO-R mRNA transcription. Nuclear co-immunoprecipitation and chromatin immunoprecipitation were performed to assess the interaction among transcription factors HIF1α, SP1, and EGR1 in the regulation of EPO-R under hypoxia. The expression of key EPO-R transcription factors in clinical specimens were determined by immunohistochemistry. Results: Hypoxia induced a dosage and time dependent EPO-R mRNA expression in NSCLC cells. Knockdown of EPO-R reduced NSCLC cell growth under hypoxia (P < 0.05). Mechanistically, a SP1-EGR1 overlapped DNA binding sequence was essential to the hypoxia induced EPO-R transcription. In the early phase of hypoxia, HIF1α interacted with EGR1 that negatively regulated EPO-R. With the exit of EGR1 in late phase, HIF1α positively regulated EPO-R expression through additive interaction with SP1. In clinical NSCLC specimen, SP1 was positively while EGR1 was negatively associated with active EPO-R expression (P < 0.05). Conclusions: HIF1α, SP1 and EGR1 mediated EPO-R expression played an essential role in hypoxia-induced NSCLC cell proliferation. Our study presents a novel mechanism of EPO-R regulation in the tumor cells, which may provide information support for NSCLC diagnosis and treatment.

Original languageEnglish (US)
Article number152
JournalCell Communication and Signaling
Volume17
Issue number1
DOIs
StatePublished - Nov 21 2019
Externally publishedYes

Keywords

  • EPO-R
  • Hypoxia
  • NSCLC

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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