1. Academic Validation
  2. STAT3 induces G9a to exacerbate HER3 expression for the survival of epidermal growth factor receptor-tyrosine kinase inhibitors in lung cancers

STAT3 induces G9a to exacerbate HER3 expression for the survival of epidermal growth factor receptor-tyrosine kinase inhibitors in lung cancers

  • BMC Cancer. 2019 Oct 16;19(1):959. doi: 10.1186/s12885-019-6217-9.
Yi-Fang Chang 1 2 3 Ken-Hong Lim 1 2 3 Ya-Wen Chiang 2 3 Zong-Lin Sie 4 Jungshan Chang 5 Ai-Sheng Ho 6 Chun-Chia Cheng 7
Affiliations

Affiliations

  • 1 Division of Hematology and Oncology, Department of Internal Medicine, Mackay Memorial Hospital, Taipei, Taiwan.
  • 2 Laboratory of Good Clinical Research Center, Department of Medical Research, Mackay Memorial Hospital, Tamsui District, New Taipei City, Taiwan.
  • 3 Department of Medicine, Mackay Medical College, New Taipei City, Taiwan.
  • 4 Institute of Molecular and Genomic Medicine, National Health Research Institute, Miaoli, Taiwan.
  • 5 Graduate Institute of Medical Sciences, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
  • 6 Division of Gastroenterology, Cheng Hsin General Hospital, Taipei, Taiwan.
  • 7 Radiation Biology Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan. cccheng.biocompare@gmail.com.
Abstract

Background: HER3 mediates drug resistance against epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs), resulting in tumor relapse in lung cancers. Previously, we demonstrated that EGFR induces HER3 overexpression, which facilitates the formation of Cancer stem-like tumorspheres. However, the cellular mechanism through which EGFR regulates HER3 expression remains unclear. We hypothesized that EGFR downstream of STAT3 participates in HER3 expression because STAT3 contributes to Cancer stemness and survival of EGFR-TKI resistant cancers.

Methods: First, RNAseq was used to uncover potential genes involved in the formation of lung Cancer HCC827-derived stem-like tumorspheres. EGFR-positive lung Cancer cell lines, including HCC827, A549, and H1975, were individually treated with a panel containing 172 therapeutic agents targeting stem cell-associated genes to search for potential agents that could be applied against EGFR-positive lung cancers. In addition, gene knockdown and RNAseq were used to investigate molecular mechanisms through which STAT3 regulates tumor progression and the survival in lung Cancer.

Results: BBI608, a STAT3 Inhibitor, was a potential therapeutic agent that reduced the cell viability of EGFR-positive lung Cancer cell lines. Notably, the inhibitory effects of BBI608 were similar with those associated with YM155, an ILF3 inhibitor. Both compounds reduced G9a-mediated HER3 expression. We also demonstrated that STAT3 upregulated G9a to silence miR-145-5p, which exacerbated HER3 expression in this study.

Conclusions: The present study revealed that BBI608 could eradicate EGFR-positive lung cancers and demonstrated that STAT3 enhanced the expression of HER3 through miR-145-5p repression by G9a, indicating that STAT3 is a reliable therapeutic target against EGFR-TKI-resistant lung cancers.

Keywords

BBI608; EGFR; G9a; HER3; Lung cancer; STAT3.

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