Exogenous progestagens and the human breast

The role of progestins (or progestagens) on the breast tissue remains controversial. However, according to the molecule and the duration of application, cell differentiation and apoptosis may predominate over proliferation. Progestins are also used as second-line agents for the treatment of metastatic breast cancer. In young women with benign breast disease, long-term treatment with 19-nortestosterone progestins had a trend to decrease breast cancer risk contrarily to what was observed in postmenopausal women receiving estrogens. Several compounds with progestational activity have been used for HRT. Small differences in the structure of the molecules may lead to pronounced differences in activities, some progestins exerting androgenic effects and some exerting estrogenic or glucocorticoid like activities. While most progestins do not bind to the estrogen receptors, it has been shown that some androgenic progestins stimulate MCF7 cells proliferation while progestins derived from progesterone did not induce cell multiplication in the same cell lines. Therefore, different progestins may induce different effects on the breast cells. Whether the progestins available to date are able to bind specifically to the progesterone receptors PR-A or PR-B and whether this is of clinical relevance to breast cell proliferation is still unclear. Although the relationship between progestin use and breast cancer risk is still the subject of debate and controversy, the data reported to date suggest that 5 years of treatment carry a low risk but further duration of use increases the risk. Further studies are still needed, randomised long-term prospective studies as well as from the laboratory, especially to determine whether a sequential or continuous regimen would be preferable as far as breast-cell response and apoptosis are concerned, and what are the effects of the various molecules used for HRT.     

Progestogens in hormonal replacement therapy: new molecules, risks, and benefits.

While the benefits of progestogen use in hormone replacement therapy (HRT) are well recognized as far as endometrial protection is concerned, their risks and drawbacks have generated controversial articles. Several risks are attributed to progestogens as a class-effect; however, the progestogens used in HRT have varying pharmacological properties and do not induce the same side effects. Natural progesterone (P) and some of its derivatives, such as the 19-norprogesterones (Nestorone, nomegestrol acetate, trimegestone), do not bind to the androgen receptor and, hence, do not exert androgenic side effects. Newly synthesized molecules such as drospirenone or dienogest have no androgenic effect but do have a partial antiandrogenic effect. Drospirenone derives from spironolactone and binds to the mineralocorticoid receptor. When the cardiovascular risk factors are considered, some molecules with a higher androgenic potency than others attenuate the beneficial effects of estrogens on the lipid profile as well as the vasomotion. On the other hand, other progestogens devoid of androgenic properties do not exert these deleterious effects. The epidemiological data do not suggest any negative effect of the progestogens administered together with estrogens on cardiovascular morbidity or mortality. However, recent results suggest that in women with established coronary heart disease, HRT may not protect against further heart attacks when the progestogen selected possesses androgenic properties. The data related to the progestogen effect on breast tissue has been interpreted differently from country to country. However, it has been admitted that, according to the type of progestogen used and the dose and duration of its application, a predominant antiproliferative effect is observed in the human breast cells. As far as breast cancer risk is concerned, most epidemiological studies do not suggest any significant difference between the estrogens given alone or combined with progestogens in HRT. Complying with the classic contraindications of HRT and selecting molecules devoid of estrogenic, androgenic, or glucocorticoid effect should allow a larger use of the progestins without any major drawback.     

Breast cancer risk in the WHI study: the problem of obesity

In the climacteric, about 40% of the women have occult breast tumors the growth of which may be stimulated by hormones. Many genetic, reproductive and lifestyle factors may influence the incidence of breast cancer. Epidemiological data suggest that the increase in the relative risk (RR) of breast cancer induced by hormone replacement therapy (HRT) is comparable with that associated with early menarche, late menopause, late first birth, alcohol consumption, etc. One of the most important risk factors is obesity which exceeds the effect of HRT by far, and in overweight postmenopausal women the elevated risk of breast cancer is not further increased by HRT. As in the WHI study the majority of women was overweight or obese, this trial was unsuitable for the investigation of breast cancer risk. In the women treated with an estrogen/progestin combination, the RR of breast cancer rose only in those women who have been treated with hormones prior to the study, suggesting a selection bias. In the women not pretreated with hormones, it was not elevated. In the estrogen-only arm of the WHI study, there was no increase but a steady decrease in the RR of breast cancer during 6.8 years of estrogen therapy. This result was unexpected, as estrogens are known to facilitate the development and growth of breast tumors, and the effect is enhanced by the addition of progestins. Obese women are at high risk to develop a metabolic syndrome including insulin resistance and hyperinsulinemia. In postmenopausal women, elevated insulin levels are not only associated with an increased risk for cardiovascular disease, but also for breast cancer. This might explain the effects observed in both arms of the WHI study: HRT with relative low doses of estrogens may improve insulin resistance and, hence, reduce the elevated breast cancer risk in obese patients, whereas this beneficial estrogen effect may be antagonized by progestins. The principal options for the reduction of breast cancer risk in postmenopausal women are the prevention of overweight and obesity to avoid the development of hyperinsulinemia, the medical treatment of insulin resistance, the use of low doses of estrogens and the reduction of exposure to progestins. The latter might include long-cycles with the sequential use of appropriate progestins every 3 months for 14 days. There are large inter-individual variations in the proliferative response to estrogens of the endometrium. Control by vaginalsonography and progestin challenge tests may help to identify those women who may be candidates for low-dose estrogen-only therapy.     

Curcumin inhibits MPA-induced secretion of VEGF from T47-D human breast cancer cells

OBJECTIVE: Recent clinical trials show that women who receive combined estrogen and progestin hormone therapy (HT) have a higher risk of breast cancer than women who receive estrogen alone or placebo. We have shown that progestins stimulate expression of vascular endothelial growth factor (VEGF), a potent angiogenic factor, in human breast cancer cells that express the progesterone receptors and mutant p53 protein. Because increased levels of VEGF promote tumor progression, compounds that prevent progestin-induced expression of VEGF could be clinically useful. The objective of this study was to examine whether the polyphenol compound curcumin has the capacity to block progestin-induced secretion of VEGF from T47-D human breast cancer cells. DESIGN: The estrogen and progesterone receptor containing T47-D human breast cancer cells was exposed to 10 nM progesterone or synthetic progestins and varying concentrations of curcumin to determine whether curcumin blocks progestin-dependent production of VEGF from tumor cells. RESULTS: Curcumin (0.001-10 microM for 18 h) reduced medroxyprogesterone acetate (MPA)-induced secretion of VEGF from T47-D cells in a dose-dependent manner. Secretion of VEGF from cells treated with progesterone or progestins other than MPA was unaffected by curcumin. CONCLUSIONS: MPA is the most widely used progestin in HT. Curcumin may therefore provide a clinically useful tool for the suppression of MPA-induced elaboration of VEGF by tumor cells. We propose therefore that clinical trials to assess the beneficial effects of curcumin in postmenopausal women are warranted.     

miR-342-3p 在乳腺癌中的表达及其与临床病理特征、 远期预后的相关性

目的研究 miR-342-3p 在乳腺癌中表达及其与临床病理特征、 远期预后的相关性。方法选择 2014 年 1 月 ~ 2015 年 2 月期间在南平市第一医院接受乳腺癌根治术的患者作为乳腺癌组, 同期接受手术切 除的乳腺良性肿瘤患者作为对照组, 检测乳腺癌组织及乳腺良性肿瘤组织中 miR-342-3p 的表达水平, 随访 乳腺癌患者的总生存 (OS) 及无病生存 (DFS), 采用 Kaplan-Meier 曲线分析 miR-342-3p 的表达水平与 OS、 DFS 的关系, 采用 COX 比例风险模型分析 OS、 DFS 的影响因素。 在乳腺癌 MCF7 细胞中转染 miR-NC 序列及 miR-342-3p 模拟物, 检测细胞活力水平及 AKT2、 Bcl2L1、 FOXQ1 的表达水平。结果乳腺癌组织 中 miR-342-3p 的表达水平明显低于乳腺良性肿瘤组织 (P< 0. 05), 且不同 T 分期、 淋巴结转移、 分子分 型、 Ki-67 表达的乳腺癌组织间比较, miR-342-3p 表达水平有显著差异 (P< 0. 05)。 Kaplan-Meier 曲线分析 显示, 相比于 miR-342-3p 高表达患者, miR-342-3p 低表达患者的 DFS 和 OS 均缩短。 COX 比例风险模型分 析显示, 淋巴结转移、 Ki-67 表达、 miR-342-3p 表达是乳腺癌患者 DFS 和 OS 的影响因素。 miR-342-3p 高表 达的乳腺癌组织中 AKT2、 Bcl2L1、 FOXQ1 的表达水平低于 miR-342-3p 低表达的乳腺癌组织。 miR-342-3p 组 MCF7 细胞中细胞活力及 AKT2、 Bcl2L1、 FOXQ1 的表达水平均低于 miR-NC 组。结论乳腺癌中 miR-342-5p 低表达且其低表达与病理特征恶化有关, miR-342-5p 低表达是乳腺癌患者预后的影响因素, AKT2、 Bcl2L1、 FOXQ1 可能是 miR-342-5p 参与乳腺癌发展的潜在分子机制。     

Differential effects of progestogens, by type and regimen, on estrogen-metabolizing enzymes in human breast cancer cells

OBJECTIVES: To investigate the in vitro effects of five progestogens commonly used in hormone replacement therapy (HRT) on estrogen-metabolizing enzymes in human breast cancer cells. METHODS: The human hormone-dependent breast cancer cell lines T47D, MCF-7, and MCF-7aro were cultured with estradiol (E(2)) and progestogens. The mRNA levels of estrogen-metabolizing enzymes were determined by RT-PCR or Northern blot, and enzyme activities by radiolabeled substrates. Cell proliferation was measured by bromodeoxyuridine incorporation. In vitro models for continuous combined regimen (CCR) and sequential combined regimen (SCR) were established to mimic the in vivo conditions of HRT. RESULTS: Medroxyprogesterone acetate (MPA) plus E(2) (10(-8)M) stimulated the mRNA levels and activities of estrogen-activating enzymes aromatase (at 10(-8)M MPA), 17beta-hydroxysteroid dehydrogenase type 1 (17betaHSD1) (at 10(-6)M), and sulfatase (at 10(-8) to 10(-6)M) compared to E(2) only. Progesterone also stimulated enzyme activity, but to a lower magnitude. Levonorgestrel, norethindrone, and dienogest showed no enzyme stimulation. The estrogen-inactivating enzymes 17beta-hydroxysteroid dehydrogenase type 2 and sulfotransferase were not affected by any of the progestogens tested. However, all the progestogens (at 10(-8) to 10(-6)M) inhibited E(2)-stimulated cell proliferation. While increased aromatase and 17betaHSD1 activities were observed in the CCR model, no significant enzyme stimulation was observed in the SCR model. CONCLUSIONS: The present study suggested that progestogens exert different actions on estrogen-metabolizing enzymes in breast cancer cells dependent on the specific progestogen and regimen used. Further studies are needed to elucidate whether MPA, a progestogen currently used in HRT, leads to a higher risk of breast cancer development than other progestogens.     

Prevention of postmenopausal bone loss with long-cycle hormone replacement therapy

OBJECTIVE: Postmenopausal bone loss and osteoporotic fractures can be prevented by hormone replacement therapy (HRT). However, opposed HRT may increase the risk of breast cancer above that associated with estrogen alone and in non-hysterectomized women estrogen substitution alone increases the risk of uterine cancer, which triggered renewed interest in long-cycle HRT regimens (estrogen replacement therapy with progesterone-free intervals up to 6 months). The effects on bone of such long-cycle HRT regimens are unknown. The objective of the present study was to compare the effects on bone and the endometrium of long-cycle HRT and conventional HRT. METHODS: Seventy-three healthy non-hysterectomized postmenopausal women were randomized to either conventional HRT (estradiol (E2) 2 mg/d during 12 days, E2 2 mg/d plus 1 mg/d of norethisterone acetate (NETA) during 10 days, E2 1 mg/d for 6 days) or long-cycle HRT treatment (two cycles with E2 2 mg/d during 28 days, followed by one cycle of conventional HRT and repeated every 3 months). Primary endpoint was the change in bone mineral density (BMD) at the lumbar spine (LS) over 24 months. RESULTS: BMD at LS increased significantly versus baseline in both treatment groups (conventional HRT +3.8 +/- 0.6%, long-cycle HRT +3.3 +/- 0.5%, p < 0.0001 for both) with no significant difference between treatment groups over 24 months. Similar significant BMD increases versus baseline were observed at the femoral neck, while biochemical markers of bone turnover (osteocalcin and deoxypyridinoline) were significantly decreased over 24 months. There were no endometrial or breast related adverse events reported. CONCLUSION: Long-cycle HRT may be a valid alternative to conventional HRT with regard to protection against postmenopausal bone loss.     

Antiestrogen action of progesterone in the breast

This review analyzes recent data from international literature concerning the antiestrogen action of progesterone, progestins and the antiprogesterone RU 486 at the level of mammary cells in culture from either breast cancer lines or normal breast obtained from reduction mammoplasties. Most data indicate that progesterone, progestins and even RU 486 have a strong antiestrogen effect on breast cell appreciated by the decrease of estradiol receptor content, the decrease of cell multiplication and the stimulation of 17 beta-hydroxysteroid activity which may be considered as a marker of breast cell differentiation dependent of progesterone receptor.     

Ulipristal acetate does not impact human normal breast tissue

BACKGROUND Antiprogestins are of growing interest for the development of new treatments in the gynecological field. Ulipristal acetate (UPA) is a progesterone receptor (PR) modulator considered for long-term administration in contraception and is currently being registered for the treatment of uterine fibroids. In light of the influences of hormonal dysfunction in breast pathologies, the secondary consequences of chronic UPA therapy need to be established. The aim of this study was to determine UPA actions mediated by PR and glucocorticoid receptor (GR) in normal and transformed breast. METHODS UPA, progesterone (P) and dexamethasone (DEX) effects were observed on PR and GR responsive genes and on proliferation and apoptosis of normal human breast epithelial (HBE) and breast cancer cells. Human normal breast tissue samples were xenografted in athymic mice and treated with estradiol (E2), or E2 + P, or E2 + P + UPA. RESULTS Analysis of PR and GR reporter gene transactivation and their respective endogenous target genes indicated that UPA exerted anti-progestational and anti-glucocorticoid activity in both types of cells with a more pronounced effect in cancer cells. When combined with P or DEX, UPA limits the proliferation of HBE cells but increases growth in breast cancer cell lines. UPA administration had no impact on the mitotic index on xenografted human breast tissue exposed to gonadal hormones at similar concentrations to those present in normal women. CONCLUSIONS Although further clinical trials are required to confirm that the results from our experimental models can be extrapolated to women treated with UPA, they suggest that such treatment would not be deleterious to normal breast tissue at least for a cycle (28 days) of continuous administration.     

Medroxyprogesterone acetate inhibits proliferation of colon cancer cell lines by modulating cell cycle-related protein expression

OBJECTIVE: To investigate the effects of medroxyprogesterone acetate on colon cancer cells in vitro. DESIGN: HT29 and HCT116 human colon cancer cell lines were used in this study. Cell growth and WST-1 assays were performed to investigate the antiproliferative effect of medroxyprogesterone acetate. Cell cycle analysis was performed to investigate the effects of medroxyprogesterone acetate on cell cycle distribution. Western blot, immunoprecipitation, and a cyclin-dependent kinase assay were performed to investigate changes in the levels of cell cycle proteins. RESULTS: Medroxyprogesterone acetate inhibited proliferation of the cancer cells by inducing accumulation in the G0/G1 fraction. Medroxyprogesterone acetate decreased expression of cyclin E, increased expression of p21(WAF1/CIP1), and enhanced interaction of p21(WAF1/CIP1) with cyclin-dependent kinase 2, eventually inhibiting its activity. CONCLUSIONS: Medroxyprogesterone acetate exerts its antiproliferative effect by modulating cell cycle-related protein expression and cyclin-dependent kinase 2 activity. These results should help to elucidate the protective effect of medroxyprogesterone acetate on colon cancer risk.     

Effects of bisphenol compounds on the growth and epithelial mesenchymal transition of MCF-7 CV human breast cancer cells

Bisphenol-A (BPA) has been considered as an endocrine disrupting chemical (EDC) because it can exert estrogenic properties. For bisphenol-S (BPS) and bisphenol-F (BPF) that are BPA analogs and substitutes, their risk to estrogendependent cancer has been reported rarely compared with the numerous cases of BPA. In this study, we examined whether BPA, BPS, and BPF can lead to the proliferation, migration, and epithelial mesenchymal transition (EMT) of MCF-7 clonal variant (MCF-7 CV) breast cancer cells expressing estrogen receptors (ERs). In a cell viability assay, BPA, BPS, and BPF significantly increased proliferation of MCF-7 CV cells compared to control (DMSO) as did 17β-estradiol (E2). In Western blotting assay, BPA, BPS, and BPF enhanced the protein expression of cell cycle progression genes such as cyclin D1 and E1. In addition, MCF-7 CV cells lost cell to cell contacts and acquired fibroblast-like morphology by the treatment of BPA, BPS, or BPF for 24 hours. In cell migration assay, BPA, BPS, and BPF accelerated the migration capability of MCF-7 CV cells as did E2. In relation with the EMT process, BPA, BPS, and BPF increased the protein expression of N-cadherin, while they decreased the protein expression of Ecadherin. When BPA, BPS, and BPF were co-treated with ICI 182,780, an ER antagonist, proliferation effects were reversed, the expression of cyclin D1 and cyclin E1 was downregulated, and the altered cell migration and expression of N-cadherin and E-cadherin by BPA, BPS, and BPF were restored to the control level. Thus, these results imply that BPS and BPF also have the risk of breast cancer progression as much as BPA in the induction of proliferation and migration of MCF-7 CV cells by regulating the protein expression of cell cycle-related genes and EMT markers via the ER-dependent pathway.     

Controversy between estrogen replacement therapy and risk of breast cancer in menopause

At present, no information is available from controlled prospective randomized clinical trials to demonstrate a causal link between estrogen replacement therapy (HRT) and the risk of developing breast cancer. In most epidemiologic studies, HRT is not associated with an major increased risk of breast cancer; thus for women who had used estrogen for 10 years or more, the relative risk of breast cancer is 1.46 which is considered as small magnitude. Clinicians and patients are challenged with the difficult task of balancing the beneficial effects of HRT on cardiovascular and bone disease with the potential adverse effects on the breast. The analyses of the benefits and risks of HRT generally indicate that the benefits of therapy outweigh the risks. In other respect the number of survivors of breast cancer are increasing rapidly because of both early detection and the availability of more effective treatments. This effect will increase the number of hypoestrogenic survivors of breast cancer, a group that might benefit from HRT. However, the decision of using HRT has to be determined between the patient and the physician.     

Identification of lineariifolianoid A as a novel dual NFAT1 and MDM2 inhibitor for human cancer therapy

There is an increasing interest in development of novel anticancer agents that target oncogenes.We have recently discovered that nuclear factor of activated T cells 1(NFAT1) is a novel regulator of the Mouse Double Minute 2(MDM2) oncogene and the NFAT1-MDM2 pathway has been implicated in human cancer development and progression,justifying that targeting the NFAT1-MDM2 pathway could be a novel strategy for discovery and development of novel cancer therapeutics.The present study was designed to examine the anticancer activity and underlying mechanisms of action of lineariifolianoid A(LinA),a novel natural product inhibitor of the NFAT1-MDM2 pathway.The cytotoxicity of LinA was first tested in various human cancer cell lines in comparison with normal cell lines.The results showed that the breast cancer cells were highly sensitive to LinA treatment.We next demonstrated the effects of LinA on cell proliferation,colony formation,cell cycle progression,and apoptosis in breast cancer MCF7 and MDA-MB-231 cells,in dose-dependent and p53-independent manners.LinA also inhibited the migration and invasion of these cancer cells.Our mechanistic studies further indicated that its anticancer activities were attributed to its inhibitory effects on the NFAT1-MDM2 pathway and modulatory effects on the expression of key proteins involved in cell cycle progression,apoptosis,and DNA damage.In summary,LinA is a novel NFAT1-MDM2 inhibitor and may be developed as a preventive and therapeutic agent against human cancer.     

Progestins in the menopause in healthy women and breast cancer patients

At present, more than 200 progestin compounds are synthetized, but their biological effects are different: this is function of their structure, receptor affinity, metabolic transformations, the target tissues considered, dose. The action of progestins in breast cancer is controversial; some studies indicate an increase in breast cancer incidence, others show no differences, and yet others indicate a decrease. Many studies agree that treatment with progestins plus estrogens at a low dose and during a limited period (less than 5 years) can have beneficial effects in peri- and post-menopausal women. It was demonstrated that various progestins (e.g. nomegestrol acetate, medrogestone, promegestone), as well as tibolone and its metabolites, can block the enzymes involved in estradiol bioformation (sulfatase, 17β-hydroxysteroid dehydrogenase) in breast cancer. Progesterone is converted into various metabolic products: in normal breast tissue the transformation is mainly to 4-ene derivatives, whereas in the tumor tissue 5α-pregane derivatives are predominant. Aromatase activity is the last step in the formation of estrogens by the conversion of androgens. In recent studies it was shown that 20α-dihydroprogesterone, a metabolite found mainly in normal breast tissue and having anti-proliferative properties, can act as an anti-aromatase agent. The data suggest the possible utilization of this compound in breast cancer prevention. In conclusion, in order to clarify and better understand the response of progestins in breast cancer (incidence and mortality), as well as in hormone replacement therapy or in endocrine dysfunction, new clinical trials are necessary using other progestins in function of the dose and period of treatment.     

Urokinase-Receptor/Integrin Complexes Are Functionally Involved in Adhesion and Progression of Human Breast Cancer in Vivo

Interactions between specific cell-surface molecules, which include the urokinase receptor (uPAR) and integrins, are crucial to processes of tumor invasion and metastasis. Here we demonstrate that uPAR and beta1-integrins may cluster at distinct sites at the cell surface of metastatic MDA-MB-231 breast cancer cells and form functional complexes. Attachment assays performed in the presence of a synthetic peptide (p25), which interferes with the formation of uPAR-integrin complexes, reveal that uPAR is able to regulate the adhesive function of integrins in breast cancer cells. On dissociation of the uPAR-integrin complexes by p25, tumor cell attachment to the extracellular matrix was either decreased (vitronectin) or increased (fibronectin). Moreover, the tumor cells display remarkable morphological changes when cultured on fibronectin in the continuous presence of p25, leading to increased cell spreading and attachment. In marked contrast to control conditions, increased cellular adhesion to fibronectin after p25 treatment was entirely beta1-integrin-mediated. The role of uPAR-integrin complexes in tumor progression was studied in an in vivo bone xenograft model. Stably transfected MDA-MB-231 cells that overexpress p25 showed a significant reduction in tumor progression in bone (P < or = 0.0001 versus mock-control). In line with these observations, continuous administration of p25 (25 microg/mouse/day, osmotic minipumps) for 28 days resulted in significantly reduced tumor progression of MDA-MB-231 cells in bone (P < or = 0.005) when compared to scrambled control peptide. In conclusion, our data demonstrate that uPAR can act as an adhesion receptor in breast cancer and is capable of regulating integrin function. Our findings strongly suggest that adhesive and proteolytic events are tightly associated in metastatic breast cancer cells and that functional integrin-uPAR complexes are involved in tumor progression in vivo.     

Characterization of anti-cyclin E single-chain Fv antibodies and intrabodies in breast cancer cells: enhanced intracellular stability of novel sFv-F(c) intrabodies

Cyclin E is a critical cell cycle protein in the regulated progression of normal cells to replicate their DNA. Ectopic overexpression of cyclin E results in accelerated G(1) progression, chromosome instability, and a reduced requirement for growth factors. Dysregulated cyclin E expression is found in nearly all breast cancers examined. Toward the goal of developing a system to block cyclin E function in normal and breast cancer cells, we have developed anti-cyclin E single-chain antibodies (sFvs) for use as intrabodies. We have cloned the variable region genes from two hybridoma cell lines that produce anti-human cyclin E antibodies, linked them into sFvs, and showed their ability to bind cyclin E when expressed as sFv-F(c) fusion proteins. Engineering of the sFvs as sFv-F(c) intrabodies resulted in a dramatic increase in the sFv half-life as analyzed by pulse-chase and immunofluorescence, and these fusion intrabodies can be expressed in the cytosol or retargeted to the nucleus of breast cancer cell lines. Stable expression of a nuclear-targeted anti-cyclin E intrabody appears to inhibit the growth of the breast cancer cell line SKBR3. This work sets the stage for the development of intrabody-based inducible or tissue-specific cyclin E knockouts and for identifying cyclin E and its vital cell cycle functions as a potential gene therapy target in breast and other cancers.     

Exposure of breast cancer cells to a subcytotoxic dose of apigenin causes growth inhibition,oxidative stress,and hypophosphorylation of Akt

Epidemiological studies show that fruit- and vegetable-rich diets are associated with a reduced risk of developing certain forms of cancer, including breast cancer. In this study we demonstrate that a subcytotoxic concentration of apigenin, which is a flavone found at high concentrations in parsley, onions, grapefruit, oranges, and chamomile tea, inhibited DNA synthesis in a panel of human breast cancer cell lines (MDA-MB-231, MBA-MB-468, MCF-7, SK-BR-3). Decreased proliferation of MDA-MB-468 cells in the presence of apigenin was associated with G₂/M phase cell cycle arrest and the production of reactive oxygen species. Apigenin-treated MDA-MB-468 cells also showed reduced phosphorylation of Akt (protein kinase B), which is an essential effector serine/threonine kinase in the phosphatidylinositide 3-kinase pathway that promotes tumor growth and progression. However, exposure to the antioxidant reduced glutathione failed to reverse apigenin-mediated inhibition of Akt phosphorylation and cell proliferation, indicating that these effects were not due to oxidative stress. Taken together, these findings suggest that low-dose apigenin has the potential to slow or prevent breast cancer progression.     

Differential effects of progestins on breast tissue enzymes

There is substantial evidence that mammary cancer tissue contains all the enzymes responsible for the local biosynthesis of estradiol (E2) from circulating precursors. Two principal pathways are implicated in the final steps of E2 formation in breast cancer tissue: the 'aromatase pathway' that transforms androgens into estrogens and the 'sulfatase pathway' that converts estrone sulfate (E1S) into estrone (E1) via estrone sulfatase. The final step is the conversion of weak E1 to potent biologically active E2 via reductive 17beta-hydroxysteroid dehydrogenase type 1 activity. It is also well established that steroid sulfotransferases, which convert estrogens into their sulfates, are present in breast cancer tissues. One of the possible means of blocking E2 effects in breast cancer is to use anti-estrogens, which act by binding to the estrogen receptor (ER). Another option is to block E2 using anti-enzymes (anti-sulfatase, anti-aromatase, or anti-17beta-hydroxysteroid dehydrogenase (17beta-HSD). Various progestins (e.g. promegestone, nomegestrol acetate, medrogestone, 17-deacetyl norgestimate, dydrogesterone and its 20-dihydro derivative), as well as tibolone and its metabolites, have been shown to inhibit estrone sulfatase and 17beta-hydroxysteroid dehydrogenase. Some progestins and tibolone can also stimulate sulfotransferase activity. These various progestins may therefore provide a new option for the treatment of breast cancer.     

Hormone replacement therapy: the perspectives for the 21st century.

Nowadays different lines of evidence demonstrate the benefits of postmenopausal hormone replacement therapy (HRT). HRT is extremely effective in treating subjective symptoms and can really improve the quality of life of climacteric women. HRT and dementia: Estrogens are potentially relevant to the pathogenesis and treatment of Alzheimer's disease. The effects of different progestogens on cognitive functions and Alzheimer's disease are largely unknown. The prevention of Alzheimer disease might be a major indication to long term HRT. Large prospective, randomized trials will confirm these preliminary data. HRT and osteoporosis: HRT has been strongly correlated with higher bone mineral density and lower fracture incidence. Definite answers in terms of minimum effective dosages, timing and duration of HRT for fracture prevention are needed. HRT and cardiovascular disease: Different lines of evidence suggest that HRT can exert cardioprotective effects with substantial reduction of morbidity and mortality for cardiovascular disease in postmenopausal women. The effects and the role of progestogens in cardiovascular disease prevention are still debated. Prospective, randomized, controlled studies are needed to assess the impact of different HRT regimens on cardiovascular events. HRT and cancer: The major issue in the relationship between HRT and cancer is breast cancer. Long-term and current HRT use are followed by a slight, though significant increase in the risk of breast cancer. Progestogens can modify the cellular response of normal as well as cancer breasts. The possible protective effect of continuous progestogen addition is very interesting and needs further investigation. Alternative to classical HRT: Selective estrogen receptor modulators (SERM). SERMs such as raloxifene (RAL) are a new class of drugs that exert site specific estrogenic or antiestrogenic effects in different target tissues. RAL prevents bone loss and reduces serum cholesterol in postmenopausal women. In contrast to estrogen RAL does not stimulate breast or uterine tissues. In vitro RAL is highly effective at inhibiting the growth of estrogen-dependent breast adenocarcinoma cells. SERMs are expected to represent a major breakthrough for postmenopausal health. CONCLUSION: HRT can be offered either as a preventive tool or as individualized care on the basis of personal needs. New therapeutic options like the SERMs will offer a substantial medical advancement for the treatment of postmenopausal women.