Effect of tamoxifen on pS2 expression in human breast cancers
K Motomura1, H Koyama, S Noguchi
1Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Japan.
Abstract:
pS2 protein expression is induced by estrogen through estrogen receptors (ER), and is known to be inhibited by antiestrogen in the breast cancer cell line MCF-7. The present study was undertaken to determine whether pS2 expression may be inhibited by the antiestrogen tamoxifen (TAM) human breast cancer. pS2 expression was immunohistochemically investigated in 22 patients treated preoperatively with TAM and in 45 without TAM treatment (control group). Immunostaining was considered positive when 10% of tumor cells showed cytoplasmic staining. We found that 94% of the pS2-positive tumors were ER-positive (ER+), and there was a significant association between the two proteins (p < 0.0001). In ER+ tumors, pS2 expression was seen in only 21% (3 of 14) of the TAM+ group, compared to 70% (16 of 23) of the control group. Statistical analysis of these data indicated a high likelihood (p = 0.006) of TAM treatment being associated with inhibition of pS2 expression in human breast cancers.
Insights
Tamoxifen (TAM) significantly inhibits pS2 protein expression in estrogen receptor-positive (ER+) human breast cancers. This finding suggests TAM
Area of Science:
- Oncology
- Endocrinology
- Molecular Biology
Background:
- pS2 protein expression is estrogen-dependent, mediated by estrogen receptors (ER).
- Antiestrogens, like tamoxifen (TAM), are known to inhibit pS2 in cell lines.
- Investigating TAM's effect on pS2 in human breast cancer is crucial.
Purpose of the Study:
- To determine if tamoxifen (TAM) inhibits pS2 protein expression in human breast cancer.
- To assess the association between pS2 expression, ER status, and TAM treatment.
Main Methods:
- Immunohistochemistry was used to evaluate pS2 expression in tumor samples.
- 22 patients received preoperative TAM treatment; 45 served as a control group.
- Positive pS2 staining was defined as cytoplasmic staining in ≥10% of tumor cells.
Main Results:
- A strong association was observed between pS2 positivity and ER positivity (94%, p < 0.0001).
- In ER+ tumors, pS2 expression was significantly lower in the TAM-treated group (21%) compared to controls (70%).
- TAM treatment was strongly associated with inhibition of pS2 expression (p = 0.006).
Conclusions:
- Tamoxifen (TAM) significantly inhibits pS2 protein expression in ER-positive human breast cancers.
- This suggests a potential mechanism for TAM's anti-cancer effects in breast cancer patients.
- pS2 expression may serve as a biomarker for TAM response.
