3-Nitrobenzanthrone promotes malignant transformation in human lung epithelial cells through the epiregulin-signaling pathway

Cell Biol Toxicol. 2022 Oct;38(5):865-887. doi: 10.1007/s10565-021-09612-1. Epub 2021 May 25.

Abstract

Exposure to environmental and occupational contaminants leads to lung cancer. 3-Nitrobenzanthrone (3-nitro-7H-benz[de]anthracen-7-one, 3-NBA) is a potential carcinogen in ambient air or diesel particulate matter. Studies have revealed that short-term exposure to 3-NBA induces cell death, reactive oxygen species activation, and DNA adduct formation and damage. However, details of the mechanism by which chronic exposure to 3-NBA influences lung carcinogenesis remain largely unknown. In this study, human lung epithelial BEAS-2B cells were continuously exposed to 0-10-μM 3-NBA for 6 months. NanoString analysis was conducted to evaluate gene expression in the cells, revealing that 3-NBA-mediated transformation results in a distinct gene expression signature including carbon cancer metabolism, metastasis, and angiogenesis. Alterations in tumor-promoting genes such as EREG (epiregulin), SOX9, E-cadherin, TWIST, and IL-6 were involved in epithelial cell aggressiveness. Kaplan-Meier plotter analyses indicated that increased EREG and IL-6 expressions in early-stage lung cancer cells are correlated with poor survival. In vivo xenografts on 3-NBA-transformed cells exhibited prominent tumor formation and metastasis. EREG knockout cells exposed to 3-NBA for a short period exhibited high apoptosis and low colony formation. By contrast, overexpression of EREG in 3-NBA-transformed cells markedly activated the PI3K/AKT and MEK/ERK signaling pathways, resulting in tumorigenicity. Furthermore, elevated IL-6 and EREG expressions synergistically led to STAT3 signaling activation, resulting in clonogenic cell survival and migration. Taken together, chronic exposure of human lung epithelial cells to 3-NBA leads to malignant transformation, in which the EREG signaling pathway plays a pivotal mediating role. • Short-term exposure of lung epithelial cells to 3-NBA can lead to ROS production and cell apoptosis. • Long-term chronic exposure to 3-NBA upregulates the levels of tumor-promoting genes such as EREG and IL-6. • Increased EREG expression in 3-NBA-transformed cells markedly contributes to tumorigenesis through PI3K/AKT and MEK/ERK activation and synergistically enhances the IL-6/STAT3 signaling pathway, which promotes tumorigenicity.

Keywords: 3-Nitrobenzanthrone; Carcinogen; Epiregulin; Lung cancer; Transformation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benz(a)Anthracenes
  • Cadherins / metabolism
  • Carbon / metabolism
  • Carbon / pharmacology
  • Carcinogenesis / metabolism
  • Carcinogens
  • Cell Transformation, Neoplastic / metabolism
  • DNA Adducts* / metabolism
  • DNA Adducts* / pharmacology
  • Epiregulin / genetics
  • Epiregulin / metabolism
  • Epiregulin / pharmacology
  • Epithelial Cells / metabolism
  • Humans
  • Interleukin-6 / metabolism
  • Lung / metabolism
  • Lung Neoplasms* / chemically induced
  • Lung Neoplasms* / genetics
  • Lung Neoplasms* / metabolism
  • Mitogen-Activated Protein Kinase Kinases / genetics
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Mitogen-Activated Protein Kinase Kinases / pharmacology
  • Particulate Matter / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Reactive Oxygen Species / metabolism
  • Signal Transduction

Substances

  • Benz(a)Anthracenes
  • Cadherins
  • Carcinogens
  • DNA Adducts
  • Epiregulin
  • Interleukin-6
  • Particulate Matter
  • Reactive Oxygen Species
  • Carbon
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinase Kinases
  • 3-nitrobenzanthrone