Overexpression of Bmi-1 oncoprotein correlates with axillary lymph node metastases in invasive ductal breast cancer

Breast. 2004 Oct;13(5):383-8. doi: 10.1016/j.breast.2004.02.010.


The modulation of Bmi-1 is observed in several tumor tissues, and its heightened protein level is suspected to be involved in tumorigenesis by acting as a transcriptional repressor in the INK4a/ARF locus. To elucidate the modulation of Bmi-1 in invasive ductal breast cancers, we examined its transcript and protein levels. The bmi-1 mRNA level by reverse transcription-polymerase chain reaction (RT-PCR) showed that it was significantly up-regulated in 28 specimens out of 33 breast carcinoma tissues compared with those of non-neoplastic tissues just adjusted to tested specimens. Immunohistochemical staining for Bmi-1 also showed that 44 specimens out of 71 breast carcinoma tissues (62%) had strong positive signals with a more intense staining pattern in the invading fronts than in the central portions of primary invasive breast cancers. Univariate and multivariate analyses showed that a high level of Bmi-1 expression was significantly correlated with axillary lymph node metastases and positive estrogen receptor status. These findings suggested that Bmi-1 might be involved in the tumor progression and metastasis of invasive ductal breast cancer.

MeSH terms

  • Axilla
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Carcinoma, Ductal, Breast / metabolism*
  • Carcinoma, Ductal, Breast / pathology
  • Female
  • Humans
  • Lymphatic Metastasis
  • Middle Aged
  • Nuclear Proteins / biosynthesis*
  • Oncogene Proteins / biosynthesis
  • Polycomb Repressive Complex 1
  • Proto-Oncogene Proteins / biosynthesis*
  • Receptors, Steroid / biosynthesis
  • Repressor Proteins / biosynthesis*


  • BMI1 protein, human
  • Nuclear Proteins
  • Oncogene Proteins
  • Proto-Oncogene Proteins
  • Receptors, Steroid
  • Repressor Proteins
  • Polycomb Repressive Complex 1