Histone-acetylated control of fibroblast growth factor receptor 2 intron 2 polymorphisms and isoform splicing in breast cancer

Mol Endocrinol. 2009 Sep;23(9):1397-405. doi: 10.1210/me.2009-0071. Epub 2009 Jun 4.

Abstract

Recent genome-wide association studies have identified fibroblast growth factor receptor (FGFR)2 as one of a few candidate genes linked with breast cancer susceptibility. In particular, the disease-predisposing allele of FGFR2 is inherited as a 7.5-kb region within intron 2 that harbors eight single nucleotide polymorphisms. The relationship between these single nucleotide polymorphisms and FGFR2 gene expression remains unclear. Here we show the common occurrence of polymorphisms within the intron 2 region in a panel of 10 breast cancer cell lines. High FGFR2-expressing cell lines such as MCF-7 cells displayed polymorphic sequences with constitutive histone acetylation at multiple intron 2 sequences harboring putative transcription binding sites. Knockdown of Runx2 or CCAAT enhancer binding protein beta in these cells resulted in diminished endogenous FGFR2 gene expression. In contrast FGFR2-negative MDA-231 cells were wild type and showed evidence of histone 3/4 deacetylation at the rs2981578, rs10736303, and rs7895676 disease-associated alleles that harbor binding sites for Runx2, estrogen receptor, and CCAAT enhancer binding protein beta, respectively. Histone deacetylation inhibition with trichostatin A resulted in enhanced acetylation at these intron 2 sites, an effect associated with robust FGFR2 reexpression. Isoform analysis proved reexpression of the FGFR2-IIIc variant the splicing of which was positively influenced by trichostatin A-mediated recruitment of the Fas-activated serine/threonine phosphoprotein survival protein. Our findings highlight the potential role of histone acetylation in modulating access to selected polymorphic sites within intron 2 as well as downstream splicing sites in generating variable FGFR2 levels and isoforms in breast cancer.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylation
  • Alternative Splicing*
  • Animals
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Cell Line, Tumor
  • Female
  • Histones / chemistry*
  • Humans
  • Introns*
  • Mammary Neoplasms, Animal / metabolism*
  • Mice
  • Mice, SCID
  • Neoplasm Transplantation
  • Polymorphism, Genetic*
  • Protein Isoforms
  • Receptor, Fibroblast Growth Factor, Type 2 / genetics*

Substances

  • Histones
  • Protein Isoforms
  • Receptor, Fibroblast Growth Factor, Type 2