Beta-carotene and apocarotenals promote retinoid signaling in BEAS-2B human bronchioepithelial cells

Arch Biochem Biophys. 2006 Nov 1;455(1):48-60. doi: 10.1016/j.abb.2006.08.023. Epub 2006 Sep 20.

Abstract

High dose beta-carotene supplementation of smokers was associated with increased lung cancer risk in two intervention trials. It was proposed that generation of apocarotenals in smoke-exposed lungs impaired retinoic acid (RA) signaling, leading to squamous metaplasia and cell proliferation. To test this, we compared RA target gene regulation by retinoids, apocarotenals or beta-carotene by transcriptomics in BEAS-2B cells cultured to promote squamous differentiation. Retinoids, beta-carotene as well as apocarotenals induced known RA target genes. Retinoids upregulated involucrin, indicating that retinoids did not rescue BEAS-2B cells from squamous differentiation. Muc5AC, a marker for mucous differentiation, was transiently induced. beta-Carotene and apocarotenals less strongly induced involucrin and did not induce muc5AC. In summary, apocarotenals or beta-carotene upregulated RA target genes suggesting promotion, not inhibition, of RA signaling in BEAS-2B cells. Furthermore, apocarotenals and beta-carotene regulated gene expression independently of RA signaling. Squamous differentiation is not unequivocally linked to RA deficiency in BEAS-2B cells.

MeSH terms

  • Bronchi / cytology
  • Bronchi / drug effects
  • Bronchi / metabolism
  • Carotenoids / metabolism
  • Carotenoids / pharmacokinetics
  • Carotenoids / pharmacology*
  • Cell Differentiation / drug effects
  • Cell Line
  • Chromatography, High Pressure Liquid
  • Cluster Analysis
  • Dose-Response Relationship, Drug
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Gene Expression / drug effects
  • Gene Expression Profiling
  • Humans
  • Oligonucleotide Array Sequence Analysis / methods
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Retinoids / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Signal Transduction / drug effects*
  • Time Factors
  • beta Carotene / metabolism
  • beta Carotene / pharmacokinetics
  • beta Carotene / pharmacology*

Substances

  • RNA, Messenger
  • Retinoids
  • beta Carotene
  • Carotenoids
  • apocarotenal