Binding of lactoferrin to IGBP1 triggers apoptosis in a lung adenocarcinoma cell line

Anticancer Res. 2011 Feb;31(2):529-34.

Abstract

Background: Lactoferrin (Lf), an iron-binding protein present in mammalian secretions, plays important roles in cancer prevention by inducing apoptosis.

Materials and methods: PC-14 lung adenocarcinoma cells were exposed to bovine Lf (bLf) protein and the expression of caspase-3 and apoptosis protease-activating factor-1 (APAF-1) was assessed. To investigate the molecular mechanism of apoptosis induced by bLf, a major Lf-binding protein was screened using a protein microarray with bLf protein as the probe. Protein interaction was demonstrated by co-immunoprecipitation, immunofluorescence and phosphatase activity assay.

Results: Lf directly suppressed the proliferation of the PC-14 cells by triggering their apoptosis. Lf was shown to bind specifically with a 36-kDa protein, immunoglobulin (CD79A)-binding protein 1 (IGBP1). The binding complex interacted with the catalytic subunit of protein phosphatase 2A (PP2A), thus reducing the phosphatase activity of PP2A and triggering apoptosis.

Conclusion: Lf binds IGBP1 and promotes the acceleration of cellular apoptosis.

MeSH terms

  • Adenocarcinoma / drug therapy
  • Adenocarcinoma / metabolism
  • Adenocarcinoma / pathology
  • Adenocarcinoma of Lung
  • Animals
  • Apoptosis / drug effects*
  • Apoptosis / physiology
  • Cattle
  • Cell Growth Processes / drug effects
  • Cell Growth Processes / physiology
  • Cell Line, Tumor
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Lactoferrin / metabolism
  • Lactoferrin / pharmacology*
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology
  • Microscopy, Fluorescence
  • Molecular Chaperones
  • Protein Array Analysis
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • IGBP1 protein, human
  • Intracellular Signaling Peptides and Proteins
  • Molecular Chaperones
  • Lactoferrin