Effect of antiestrogens on EGF-mediated movement of human breast cancer cells

In a previous study we compared the influence of several growth factors on breast cancer cells in culture and observed that epidermal growth factor (EGF) enhanced the invasiveness of estrogen receptor-positive breast cancer cells. The objective of the present study was to determine the influence of three unique antiestrogens on EGF-mediated movement of human breast cancer cells. The rate of movement of MCF-7 breast cancer cells was measured using time-lapse videomicroscopy (TLVM). The MCF-7 cells were pretreated with antiestrogen (either tamoxifen, ICI-182-780 (ICI) or 1,1-dichloro-cis-2,3-diarylcyclopropane (AII)) at 10(-6) mol/l for 4 days, and then treated with EGF (10(-10) mol/l) immediately prior to TLVM. EGF enhanced the motility of the MCF-7 cells at 30-90 min post-administration. However, EGF-mediated motility of the MCF-7 cells was inhibited by antiestrogen pretreatment, with TAM and ICI producing complete inhibition of EGF-induced motility. In conclusion, this study demonstrates that EGF enhances the rate of movement of MCF-7 breast cancer cells and that antiestrogen pretreatment inhibits EGF-mediated motility.     

Subcellular and extracellular localization of specific binding sites for triphenylethylene antiestrogens in human breast cancer

MCF-7 human breast cancer cell homogenates and subcellular organelles were submitted to isopycnic centrifugation on Percoll gradients to investigate the subcellular localization of triphenylethylene antiestrogen specific binding sites (AEBS). Electron microscopy revealed that gradient fractions coincident with the migration of [3H]tamoxifen-AEBS complexes were homogeneously represented by rough and smooth endoplasmic reticulum. Eighty percent of AEBS were localized in the endoplasmic reticulum [45,000 +/- 4,000 sites/cell, mean +/- S.D.), while 20% of these sites were also found in the nuclear fraction (12,000 +/- 1,000 sites/cell, mean +/- S.D.). A similar subcellular distribution of AEBS was observed in human breast cancer bioptic specimens. No differences in [3H]tamoxifen binding affinity between microsomal and nuclear AEBS were observed in MCF-7 and bioptic breast cancer. No major differences in microsomal AEBS levels were observed in the limited number of estrogen receptor-positive or -negative breast cancer specimens we have studied, whereas estrogen receptor-negative samples had higher levels of nuclear AEBS with respect to estrogen receptor-positive tumors. The presence of AEBS was also detected in the human serum of healthy and tumor-bearing subjects. The affinity and the binding specificity of serum AEBS were similar to those of intracellular AEBS. No differences in the levels of serum AEBS were observed between healthy and tumor-bearing subjects [19 +/- 4 and 22 +/- 4 pmoles/ml (mean +/- S.D.) respectively. Human serum AEBS did not appear to be associated to lipoproteins, whereas it migrated as a 5.5 S sedimenting molecule.     

Cell-growth quantitation methods for the evaluation of antiestrogens in human breast cancer cells in culture.

The antiproliferative activity of the antiestrogen, tamoxifen, on the growth of MCF-7 human breast cancer cells was evaluated using the hemocytometric trypan blue exclusion method, [3H]-thymidine incorporation, and a total protein determination. Tamoxifen was evaluated over a concentration range from 10(-9) to 10(-6) M. The hemocytometric trypan blue exclusion method and [3H]-thymidine incorporation were sensitive enough to demonstrate the inhibitory influence of tamoxifen on the proliferation of MCF-7 cells at a concentration as low as 10(-9) M. A very good correlation of these two methods was observed in the submicromolar concentration range of tamoxifen. The total protein determination method was only sensitive enough to detect the antiproliferative influence of tamoxifen at concentrations above 10(-6) M. In conclusion, the [3H]-thymidine incorporation method was found to be effective and much less time consuming than the hemocytometric trypan blue exclusion method for evaluating the antiproliferative effects of antiestrogens in cultured MCF-7 cells. However, when evaluating antiestrogens, which are cell-cycle specific, the results of the [3H]-thymidine incorporation method should be interpreted with caution.     

Antiproliferative activity of a series of novel cyclopropyl antiestrogens on MCF-7 human breast cancer cells in culture.

The potential antitumor activity of a series of novel cyclopropyl compounds, which lack estrogen agonist activity, was evaluated in estrogen receptor positive human breast cancer cells (MCF-7) in culture. The compounds were evaluated to determine their antiproliferative activity at a concentration of 1 microM at 2, 4 and 6 days of treatment by hemocytometer using the Trypan Blue exclusion method to count viable cells. Estradiol-induced reversibility of the antiproliferative activity of these compounds was also evaluated. The activity of a series of 19 diaryl- and triarylcyclopropyl compounds was examined. Thirteen compounds inhibited the growth of MCF-7 cells while six were inactive. Five of the 13 active compounds produced antiproliferative activity which was reversed by 0.1 microM estradiol. Thus, several of these novel cyclopropyl compounds may be useful in the treatment of hormone-dependent breast cancer and other estrogen-dependent tumors.     

Estrogens and antiestrogens activate hPXR

The pregnane X receptor (PXR, NR1I2) and the estrogen receptors (ERalpha, NR3A1 and ERbeta, NR3A2) bind a large number of compounds, including environmental pollutants and drugs, which exhibit remarkably diverse structural features. This prompted us to investigate if ER ligands could be PXR activators. We focused our attention on known estrogens from various chemical classes: physiological and synthetic estrogens and antiestrogens, plant and fungus estrogens, and other man-made chemicals belonging to phthalate plasticizers, surfactant-derived alkylphenols and cosmetics. Altogether, nearly 50 compounds were thus analyzed for their ability to activate human PXR in stably transfected cells, HGPXR cells, derived from HeLa cells and expressing luciferase under the control of a chimeric hPXR. Some of the newly identified hPXR activators were also checked for their ability to induce cytochrome P450 3A4 and 2B6 expressions in a primary culture of human hepatocytes. A significant proportion (54%) of compounds with estrogenic activity or able to bind ER were found to be hPXR activators: in particular, antiestrogens, mycoestrogens and phthalates. An even greater proportion is observed if estrogenic pesticides are included. Altogether, these results raise the question of the meaning and consequences of compounds with double PXR/ER activation ability.     

Pharmacogenomics and breast cancer

Germline variants can be used to study breast cancer susceptibility as well as the variable response to both drug and radiation therapy used in the treatment of breast cancer. In addition to germline high-penetrance mutations important in familial and hereditary breast cancer, a substantial component of breast cancer risk can be attributed to the combined effect of many low-risk germline polymorphisms involved in relevant pathways like those of DNA repair, adhesion, carcinogen and estrogen metabolism. Additionally, the identification of sequence variants in genes involved in response to chemotherapy and radiation treatment, has created the opportunity to apply genomics to individualized treatment. The continued insight into the molecular pathways involved in drug and radiation response has enabled progress in tailoring therapies in such a way as to both maximize efficacy and minimize toxicity. Polymorphisms in genes encoding drug-metabolizing enzymes, drug transporters and drug targets can be used to predict toxicity and response to pharmacologic agents used in breast cancer treatment. Similarly, germline variants in genes involved in DNA repair, radiation-induced fibrosis and reactive oxygen species may be used to predict response to radiation therapy. As a result, pharmacogenomics is rapidly evolving to affect the entire spectrum of breast cancer management, influencing both prevention and treatment choices.     

Tibolone and breast cancer

Tibolone is a synthetic steroid marketed for the treatment of menopausal symptoms. A cohort study of women with no history of breast cancer showed that tibolone was associated with an increased risk of breast cancer. In women with a history of breast cancer, a placebo-controlled trial showed a higher risk of breast cancer recurrence with tibolone. A placebo-controlled trial of half the standard dose of tibolone showed no increased risk of breast cancer but was interrupted due to an increased risk of stroke. In practice, it is better simply not to use tibolone.     

Diet and breast cancer

The issue of diet as a cause of breast cancer has been dominated by fat. Some have judged this convincing enough to warrant dietary recommendations aimed at prevention. Others find the evidence so far rather weak.     

Synthesis and biological activity of new halo-steroidal antiestrogens

Antiestrogen therapy is the most widely used endocrine manipulation for the treatment of breast cancer, especially in postmenopausal women. Unfortunately, the compounds presently available possess mixed agonistic/antagonistic activity, thus potentially limiting their therapeutic efficacy. Following the observations that an aliphatic chain at the 7 alpha-position of 17 beta-estradiol does not prevent binding to the estrogen receptor while halogenation of estradiol can increase the affinity of its binding (expressed as RBA) to the estrogen receptor, we have synthesized a series of new steroidal antiestrogens (6-10) which possess both an 7 alpha-undecanamide group and an halogen atom (Cl, Br, or I) at the 16 alpha-position. The stereochemistry of these compounds was unambiguously established by high-field (400-MHz) nuclear magnetic resonance. Some of the compounds obtained possess potent in vivo antiestrogenic activity. At the low twice daily 3-micrograms dose, 16 alpha-chloro 3,17 beta-diol amide, 16 alpha-iodo 3,17 beta-diol amide, 16 alpha-bromo 3,17 beta-diol amide, 16 alpha-chloro 3,17 alpha-diol amide, and 16 alpha-bromo 3,17 alpha-diol amide inhibit by 74, 63, 52, 35, and 60%, respectively, the estradiol-induced stimulation of uterine weight in ovariectomized Balb/c mice while 78-99% blockade of estradiol action is achieved at the 20-micrograms dose. These new antiestrogens show no estrogenic activity on uterine weight at the doses used while tamoxifen (2-[4-(1,2-diphenyl-1-butenyl)phenoxy]-N,N- dimethylethanamine) shows full estrogenic activity and is only a weak partial antiestrogen in the same assay.     

Bisphosphonates and breast cancer prevention

Bisphosphonates are commonly used in patients with breast cancer to reduce skeletal-related events in metastatic disease and to mitigate bone loss associated with cancer therapy in early stage disease. In addition, adjuvant breast cancer trials evaluating the oral bisphosphonate clodronate suggested a reduction in cancer recurrence, but the findings were mixed, with 2 positive and 1 negative report. In the Austrian Breast and Colorectal Cancer Study Group (ABCSG) 12 study, adding the intravenous bisphosphonate zoledronic acid to endocrine therapy in premenopausal breast cancer patients significantly prolonged disease-free survival versus endocrine therapy alone (hazard ratio = 0.68; p = 0.008) at 62 months, and reduced local, regional, and distant recurrences. Clinical trial findings from other adjuvant trials (Z-FAST, ZO-FAST), neoadjuvant studies, and studies involving disseminated tumor cells (DTCs) are generally supportive of the ABCSG-12 conclusion, and recent data from AZURE suggest the importance of menopausal status. Preclinical studies provide data on the mechanisms of action that could mediate bisphosphonate direct and indirect anti-cancer effects. Recently, several observational studies (2 cohort studies and 2 case-control analyses) have associated oral bisphosphonate use with a lower breast cancer incidence. Such reports require cautious interpretation because confounding by indication is an issue: bisphosphonates are prescribed for women with low bone mineral density, and women with low bone density are at decreased breast cancer risk.     

马莲鞍的化学成分研究

藤苦参为萝藦科植物,其主要成分为强心苷类化合物。藤苦参的抗肿瘤作用近年来逐渐受到关注。综述藤苦参中分离出的强心苷的化学结构、抗肿瘤活性、构效关系及作用机制等方面的研究进展,以期为藤苦参抗肿瘤药效成分的深入研究提供参考。

     

Underarm cosmetics and breast cancer

Although risk factors are known to include the loss of function of the susceptibility genes BRCA1/BRCA2 and lifetime exposure to oestrogen, the main causative agents in breast cancer remain unaccounted for. It has been suggested recently that underarm cosmetics might be a cause of breast cancer, because these cosmetics contain a variety of chemicals that are applied frequently to an area directly adjacent to the breast. The strongest supporting evidence comes from unexplained clinical observations showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast, just the local area to which these cosmetics are applied. A biological basis for breast carcinogenesis could result from the ability of the various constituent chemicals to bind to DNA and to promote growth of the damaged cells. Multidisciplinary research is now needed to study the effect of long-term use of the constituent chemicals of underarm cosmetics, because if there proves to be any link between these cosmetics and breast cancer then there might be options for the prevention of breast cancer.     

三阴性乳腺癌与非三阴性乳腺癌的超声特征对比分析

目的对比分析三阴性乳腺癌（TNBC）和非三阴性乳腺癌（NTNBC）的超声和病理学特征差异。方法将135例经病理证实的乳腺癌患者根据术后免疫组织化学结果分为TNBC组和NTNBC组,对比分析两组患者病灶的超声表现及临床病理特征。结果 135例乳腺癌病例中,TNBC患者占26.67%,NTNBC患者占73.33%;TNBC组和NTNBC组腋窝淋巴结转移率分别为58.33%和40.40%,差异有统计学意义（P〈0.05）;两组浸润性导管癌和非浸润性导管癌的比例相似,两组间病理类型比较,差异无统计学意义（P〉0.05）。TNBC组患者肿块边缘毛刺征、肿块内部微钙化及血流分级为Ⅱ～Ⅲ级者所占比例均明显低于NTNBC组,差异有统计学意义（P〈0.05）;两组肿块直径〉2cm者比例及肿块后方无回声衰减者比例差异无统计学意义（P〉0.05）。结论 TNBC患者的淋巴结转移率高于NTNBC患者,且TNBC患者缺少毛刺征、微钙化、丰富的血流等典型的乳腺癌超声表现,诊断检测时应注意与良性肿块间的区别,以免漏诊。