E. von Schoultz

Effects of Long-Term HRT and Tamoxifen on the Expression of Progesterone Receptors A and B in Breast Tissue from Surgically Postmenopausal Cynomolgus Macaques

Estrogen is a well-known mitogen in breast epithelium but the role of progesterone is complex and incompletely understood. In contrast to what is seen in the endometrium, combined estrogen/progestogen treatment for postmenopausal replacement (HRT) may carry a risk for breast cancer beyond that of estrogen alone. The ratio of the two progesterone receptor (PR) isoforms, PRA/PRB may define the response to progesterone in reproductive tissues. In a primate model for long-term HRT, surgically, postmenopausal cynomolgus macaques were treated for 35 months with conjugated equine estrogens (CEE), medroxyprogesterone acetate (MPA), CEE + MPA and tamoxifen (n=5 in all groups). The immunohistochemical expression of PRA, PRB and the androgen receptor (AR) in breast tissue was quantified by image analysis. Over all, the total PR immunostaining in glandular epithelium was more abundant during CEE (mean 12%) and tamoxifen (11%) treatment as compared to CEE/MPA (5%), MPA (4%) and untreated controls (6%). Differences in PRB expression were observed between treatment groups (p<0.05). In the CEE group levels of PRA were unchanged while there was a decline in the CEE/MPA group. The mean PRA/PRB ratio in the CEE group was 2.7 and in the CEE/MPA group 0.2. Treatment with tamoxifen had effects similar to those of estrogen. There was in all groups a weak positive nuclear AR immunostaining. This is the first in vivo study on the effects on long-term hormonal treatment on the expression of PR isoforms in normal primate breast tissue. The results suggest that hormonal treatments have a different influence on the PRA/PRB balance in the breast.

Tamoxifen and megestrol acetate for postmenopausal breast cancer: diverging effects on liver proteins, androgens, and glucocorticoids.

Aim: To compare the effects of tamoxifen and megestrol acetate on liver proteins, androgens, and glucocorticoids during adjuvant treatment for postmenopausal breast cancer.Methods: A subgroup of women within a large prospective multicenter trial were followed with blood sampling every 3 mo during 2 yr. Women were randomized to receive either continuous tamoxifen 40 mg/d or repeated sequential treatment with tamoxifen and megestrol acetate (MA) 160 mg/d.Results: We found profound and distinct differences between the two regimens. Tamoxifen increased steroid-binding proteins (SHBG and CBG) and suppressed circulating androgens and IGF-I. In contrast, the metabolic effects of tamoxifen were clearly antagonized by MA. There was a rise in IGF-I and marked suppression of steroid-binding proteins. Levels of free testosterone were reduced by 70%. MA also caused apparent adrenal suppression.Conclusion: The different effects on anabolic/catabolic balance and adrenal function may relate to certain clinical effects during treatment.

Expression of sex steroid receptor subtypes in normal and malignant breast tissue - a pilot study in postmenopausal women.

Female sex steroids are implied in breast cancer development. The estrogen (ER) and progesterone (PR) receptor subtypes may have different roles to modulate the cellular response. Paired samples of cancer and adjacent normal tissue were collected from postmenopausal women at surgery for ductal breast cancer. The expression of ERα, ERß, PRA and PRB was quantified by immunostaining and digitized image analysis. We found ERß to be significantly reduced in breast cancer tissue (35% vs 50%; p = 0.001) and there was also a decrease of the ERß/ERα ratio. Among women using hormones at the time of diagnosis tumor tissue showed higher values for both PRB and PRA, as compared to women without such treatment. The results extend previous animal data to be valid also in women. There is evidence that loss of ERß expression may relate to estrogen dependent tumor progression. Increased PR expression could possibly relate to breast cancer risk during combined estrogen/progestogen treatment.

p53 expression in breast and endometrium during estrogen and tamoxifen treatment of surgically postmenopausal cynomolgus macaques

Estrogens are important for both normal cell growth and malignant proliferation in the mammary gland as well as in the endometrium. Tamoxifen is a non‐steroidal anti‐estrogen widely used in breast cancer treatment. In recent years reports have been made of an increased risk of endometrial carcinoma during tamoxifen treatment. We used surgically menopausal cynomolgus macaques to study proliferation and p53 expression during hormonal replacement therapy (HRT) and tamoxifen treatment. Animals were treated continuously for 35 months with either conjugated equine estrogens (CEE; n = 20); medroxyprogesterone acetate (MPA; n =17); the combination of CEE + MPA (n = 13) or tamoxifen (n = 17) for 35 months. We found an increased expression of p53 in normal breast and endometrial tissue linked to CEE but not tamoxifen treatment. In the breast alveoli there was an association between proliferation measured by morphometry and p53 expression in all groups. However, in the endometrium CEE induced significantly more p53 positivity than tamoxifen, 9/20 vs. 3/17 in glands and 9/19 vs. 0/17 in stroma, respectively. If indeed long‐term treatment with tamoxifen as in the present study could inactivate the tumor‐suppressive function of p53, endometrial cells might thereby become more susceptible to genetic lesions associated with carcinogenesis.

Hormonal regulation of the normal breast

The breast is a target organ for reproductive hormones but basic knowledge on hormonal effects is very poor. Available data indicate that the breast is regulated in a specific manner which is distinct from the endometrium and other target organs. It seems clear that the breast undergoes cyclic changes during the menstrual cycle and that in vivo there is a direct stimulatory action of progestogens on the breast. In surgically postmenopausal female macaques continuous combined estrogen/progestogen therapy was found to induce greater proliferation than estrogen alone.

Are estrogen receptor content in breast cancer and effects of tamoxifen on sex hormone-binding globulin markers for individual estrogen sensitivity?

Individual women differ with respect to their sensitivity to estrogen and serum levels of sex hormone-binding globulin (SHBG) may reflect the individual response. We found a significant correlation between estrogen receptor (ER) concentrations in breast cancer tissue and SHBG levels during tamoxifen treatment. Estrogen sensitivity may be a general characteristic common to various organs and different between individual women.

Expression of cyclooxygenase-1 and cyclooxygenase-2, syndecan-1 and connective tissue growth factor in benign and malignant breast tissue from premenopausal women

Abstract Stromal factors have been identified as important for tumorigenesis and metastases of breast cancer. From 49 premenopausal women, samples were collected from benign or malignant tumors and the seemingly normal tissue adjacent to the tumor. The factors studied, with real-time polymerase chain reaction (PCR) and immunohistochemistry, were cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2), syndecan-1 (S-1) and connective tissue growth factor (CTGF). COX-1 and S-1 mRNA levels were higher in the malignant tumors than in normal and benign tissues. The COX-2 mRNA level was lower in the malignant tumor than in the normal tissue, while CTGF mRNA did not differ between the groups. COX-1 immunostaining was higher in stroma from malignant tumors than in benign tissues, whereas COX-2 immunostaining was higher in the malignant tissue. Glandular S-1 immunostaining was lower in malignant tumors compared to benign and normal tissues, and the opposite was found in stroma. Conclusively, mRNA levels of COX-1 and COX-2 were oppositely regulated, with COX-1 being increased in the malignant tumor while COX-2 was decreased. S-1 protein localization switched from glandular to stromal cells in malignant tissues. Thus, these markers are, in premenopausal women, localized and regulated differently in normal/benign breast tissue as compared to the malignant tumor.

Hormone therapy and estrogen receptor expression in breast cancer

Postmenopausal hormone therapy (HT) may increase breast cancer risk and influence tumor characteristics. We investigated 321 postmenopausal women aged 50–65 years, with breast cancer, diagnosed and treated at Radiumhemmet, Karolinska Hospital, during 1993–1997. In women using HT (n =90) estrogen receptor concentration (ER) at diagnosis were lower than in non-users (n =135) (1.17 vs 1.70 fmol/µg; p <0.05). HT users also had a tendency to less multifocal (5 vs 12%) (p <0.05) and metastatic disease (5% vs 2%) however this was not statistically significant. The estrogen receptor expression is always considered in the judgement on hormone dependency and the clinical decision on adjuvant endocrine therapy. A suppression of ER during HT could tentatively influence the treatment decisions in breast cancer patients and maybe disregard patients from endocrine treatment.