LAF-4 is aberrantly expressed in human breast cancer

Int J Cancer. 2005 Jul 1;115(4):568-74. doi: 10.1002/ijc.20881.


LAF-4, which encodes a nuclear protein with transactivation potential, is fused to the MLL gene in acute lymphoblastic leukemia (ALL). We identified LAF-4 as a gene that is transcriptionally deregulated in breast tumors and thus may have a pathological role in mammary tumorigenesis. In line with the previous finding that LAF-4 expression is tissue specific, we did not detect any LAF-4 mRNA in normal mammary epithelial cell lines. However, 2 of 5 breast cancer cell lines were found to express LAF-4 at both the RNA and protein levels. In 2 of 9 primary tumor-normal pairs, the expression of LAF-4 was clearly elevated in the tumor tissue. Using RNA in situ hybridization, we demonstrated that LAF-4 is expressed in mammary tumor cells but not in normal acini. In a group of 64 primary human breast tumors, we found that LAF-4 was overexpressed in approximately 20% of the cases. Although epigenetic changes may be involved in altered expression of some genes, differences in LAF-4 expression were not associated with DNA methylation of the predicted promoter region. Our results suggest that LAF-4 may be a proto-oncogene that is transcriptionally activated in some cases of breast cancer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Breast / pathology
  • Breast / physiopathology
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / surgery
  • DNA Methylation
  • DNA, Neoplasm / genetics
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Menopause
  • Nuclear Proteins / genetics*
  • Promoter Regions, Genetic
  • Proto-Oncogene Mas
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription, Genetic
  • Tumor Cells, Cultured


  • AFF3 protein, human
  • DNA, Neoplasm
  • MAS1 protein, human
  • Nuclear Proteins
  • Proto-Oncogene Mas
  • RNA, Messenger