J Korean Cancer Assoc.  2000 Jun;32(3):531-538.

The Role of bcl-2 and p53 in Tamoxifen-Induced Apoptosis of Human Breast Cancer Cell Lines

• Noh WC
• Noh DY
• Ham YH
• Kim CM
• Paik NS
• Moon NM
• Choe KJ

Abstract

PURPOSE: Tamoxifen has been well known as an effective anti-tumor agent against breast cancer. The important role of bcl-2 and p53 proteins in tamoxifen-induced apoptosis of breast cancer cells has been suggested. However, the paradoxical fact that bcl-2 over-expression is assdegrees Ciated with better prognosis in clinic has not yet been clearly explained. To investigate this paradox, we analyzed the effect and dynamics of bcl-2 and p53 on the apoptosis after treatment of breast cancer cells with tamoxifen.
MATERIALS AND METHODS
The human breast cancer cell lines MCF-7 and MB MDA-468 were treated with 17-betaestradiol (E2) and tamoxifen.
RESULTS
Following tamoxifen treatment, MCF-7 cells underwent apoptosis accompanied by reduced bcl-2 expression. E2 pre-treatment led to the inhibition of tamoxifen-mediated apoptosis and bcl-2 down-regulation. When MB MDA-468 cells were treated with E2 or tamoxifen, bcl-2 and p53 protein expression did not change and apoptosis did not develop.
CONCLUSION
We observed that the down-regulation of bcl-2 by tamoxifen treatment can facilitate the apoptosis of breast cancer cells without p53 mutations. This finding was consistent with clinical experiences in which bcl-2 positive tumors were assdegrees Ciated with more indolent phenotypes in breast cancer.

Keyword

Apoptosis; bcl-2 protein; Breast neoplasm; p53 protein; Tamoxifen

MeSH Terms

Apoptosis*
Breast Neoplasms*
Breast*
Cell Line*
Down-Regulation
Humans*
MCF-7 Cells
Phenotype
Prognosis
Tamoxifen
Tamoxifen