Timing of dietary fat exposure and mammary tumorigenesis: Role of estrogen receptor and protein kinase C activity

The possible association between a high fat diet and increased breast cancer risk has remained controversial. This largely reflects the conflicting data obtained from migrant, case control and animal studies, which generally support this association, and cohort studies which often fail to show a link between fat and breast cancer. The mammary gland is particularly sensitive to estrogens during the fetal development, leading us to hypothesize that dietary fat levels during this period may significantly influence breast cancer risk. Using chemically-induced mammary tumors in rats as our experimental model, we have demonstrated the ability of a maternal diet, high in the polyunsaturated fatty acid (PUFA) linoleic acid, to alter mammary gland differentiation, accelerate the onset of sexual maturation, and increase breast cancer risk. The mammary glands of female rats exposed to a highfat diet in utero have more of the undifferentiated structures (terminal end buds) and fewer of the differentiated structures (alveolar buds) than the glands of rats exposed to a low-fat diet in utero. Furthermore, these mammary glands contain lower levels of total estrogen receptors and have reduced total protein kinase C activity. These effects appear to be mediated by an increase in tne serum estradiol levels of pregnancy, which are elevated at least 30% in pregnant dams fed a high fat diet. Furthermore, the administration of estradiol to pregnant dams produce effects on mammary gland development, onset of puberty and sensitivity to chemical carcinogenesis comparable to those seen in the offspring of rats fed a high fat diet during pregnancy. Our results, thus, support the hypothesis based on epidemiological data that high maternal estrogen levels increase daughters' breast cancer risk. The results also suggest that a high-fat diet may be an important factor in increasing pregnancy estrogenic activity.     

Sex hormone-binding globulin, its membrane receptor, and breast cancer: a new approach to the modulation of estradiol action in neoplastic cells

The role of human Sex Hormone-Binding Globulin (SHBG), the plasma carrier of sex steroids, and its membrane receptor, SHBG-R, in estrogen-dependent breast cancer has been investigated in our laboratory in the past few years. SHBG-R is expressed in MCF-10 A cells (not neoplastic mammary cells), MCF-7 cells (breast cancer, ER positive) and in tissue samples from patients affected with ER positive breast cancer, but not in estrogen-insensitive MDA-MB 231 cells. The SHBG/SHBG-R interaction, followed by the binding of estradiol to the complex protein/receptor, causes a significant increase of the intracellular levels of cAMP, but does not modify the amount of estradiol entering MCF-7 cells. The estradiol-induced proliferation of MCF-7 cells is inhibited by SHBG, through SHBG-R, cAMP and PKA. Similarly, the proliferation rate of tissue samples positive for SHBG-R was significantly lower than the proliferation rate of negative samples. SHBG and SHBG-R could thus trigger a ‘biologic’ anti-estrogenic pathway. In order to get a more detailed knowledge of this system, we first examined the frequence of the reported mutated form of SHBG in 255 breast cancer patients. The mutated SHBG is characterized by a point mutation (Asp 327→Asn) causing an additional N-glycosylation site, which does not affect the binding of steroids to SHBG. The frequence of the mutation was significantly higher (24.5%) in estrogen-dependent breast cancers than in healthy control subjects (11.6%). This observation confirms the close relationship between SHBG and estrogen-dependent breast cancer and suggests that the mutation could modify SHBG activity at cell site. Lastly, the possibility of using SHBG to modulate the estradiol action in breast cancer was further studied by transfecting MCF-7 cells with an expression vector carrying the SHBG cDNA (study in collaboration with G.L. Hammond). Transfected cells are able to produce significant amount of SHBG in their medium, but their SHBG-R is reduced to undetectable levels. The SHBG produced by transfected MCF-7 cells is, however, able to inhibit estradiol-induced proliferation of MCF-7 cells expressing a functional receptor. Thus, the local production of SHBG obtained with transfection could be a useful tool to control cell growth in estrogen-dependent breast cancer.     

PROM2通过β-catenin/HER2通路调控乳腺癌细胞SK-BR-3的迁移、侵袭、增殖和凋亡

乳腺癌是当今威胁女性健康最主要的恶性肿瘤之一。虽然当前在乳腺癌的诊治方面获得了一定的进展,但其发病率和死亡率仍然较高,寻找有效的乳腺癌预后标记和治疗靶点是当前研究的热点。本研究通过对高通量基因表达数据库(Gene Expression Omnibus,GEO)分析发现,Prominin 2(PROM2)在诱导、增强和增殖成瘤能力的3组MCF7乳腺癌细胞中的表达,高于3组对照组MCF7细胞。且在诱导具有侵袭性的MCF10A细胞中的表达,高于未处理非侵袭性MCF10A细胞。研究选择了人乳腺癌细胞系SK-BR-3,成功地将过表达或敲减PROM2质粒转染到细胞中,并检测PROM2对SK-BR-3细胞的迁移、侵袭和增殖和凋亡的作用。划痕结果显示,敲减PROM2的SKBR-3细胞愈合面积更小(P<0.01),过表达PROM2的SK-BR-3细胞愈合面积更大(P<0.01);Transwell的结果显示,敲减PROM2的SK-BR-3细胞侵袭数量更少(P<0.01),过表达PROM2的SK-BR-3细胞侵袭数量更多(P<0.01);流式细胞术的结果显示,敲减PROM2的SK-BR-3细胞增殖能力减弱且凋亡比率增高(2.50%vs.0.93%),过表达PROM2的SK-BR-3细胞增殖能力增强且凋亡比率降低(0.43%vs.0.72%)。然后,探讨PROM2作用的可能机制。通过基因表达谱交互分析(gene expression profiling interactive analysis,GEPIA),对肿瘤基因图谱数据库(The Cancer Genome Atlas,TCGA)中的乳腺癌数据分析发现,PROM2与β-联蛋白(β-catenin)、人表皮生长因子受体2(human epidermal growth factor receptor 2,HER2)之间表达正相关。通过定量实时聚合酶链反应、免疫荧光和蛋白质印迹也发现,PROM2促进了β-联蛋白和HER2的表达。证明PROM2可能通过激活β-catenin/HER2通路,促进乳腺癌细胞SK-BR-3的迁移、侵袭和增殖,并抑制其凋亡。     

新型雌激素受体ER-α36与乳腺癌

雌激素受体(estrogen receptor,ER)是诊断和治疗乳腺癌的分子标志和靶点.雌激素受体包括ER-α和ER-β,其中ER-α有ER-α66、ER-α46和ER-α36三种亚型.ER-α36作为新型雌激素受体,参与膜起始的雌激素信号或非基因组雌激素信号转导,在肿瘤细胞的增殖、分化、侵袭和转移等过程中发挥作用.胃癌、子宫内膜腺癌、前列腺癌、尤其是乳腺癌的发生发展与ER-α36密切相关.本文介绍了ER-α36的结构域特点,ER-α36介导的信号通路及ER-α36在乳腺癌治疗中的作用研究进展.     

Estrogens in the causation of breast, endometrial and ovarian cancers - evidence and hypotheses from epidemiological findings

Estrogens along with progesterone/progestins, and other hormones, are important determinants of cancer in the breast, endometrium and ovary. Estrogens may increase the risk of breast cancer through various mechanisms and at various phases of life, with a possible synergistic effect of progesterone/progestins. Exposure to high doses of placental hormones, such as estrogens and/or progesterone, during pregnancy may play a pivotal role in reducing subsequent breast cancer susceptibility. Estrogens cause endometrial cancer, an effect that can be reduced, prevented or reversed by progesterone/progestin — if allowed to act for a sufficiently long period of each cycle. The role of sex hormones seems important for ovarian carcinogenesis. Intake of combined oral contraceptives has a substantial and well-documented protective effect on endometrial and ovarian cancer risks. Epidemiological observations and experimental data from an animal model indicate that estrogens may have an adverse effect, while progesterone/progestins have a risk reducing effect directly on the ovarian epithelium. Thus, estrogens and other sex hormones have potential effects on the three most important female cancers. Research has yet to define how some of the risk factors can be modified or treatment regimens can be improved to reduce these cancer risks.     

Glucose promotes breast cancer aggression and reduces metformin efficacy

Metformin treatment has been associated with a decrease in breast cancer risk and improved survival. Metformin induces complex cellular changes, resulting in decreased tumor cell proliferation, reduction of stem cells, and apoptosis. Using a carcinogen-induced rodent model of mammary tumorigenesis, we recently demonstrated that overfeeding in obese animals is associated with a 50% increase in tumor glucose uptake, increased proliferation, and tumor cell reprogramming to an “aggressive” metabolic state. Metformin significantly inhibited these pro-tumorigenic effects. We hypothesized that a dynamic relationship exists between chronic energy excess (glucose by dose) and metformin efficacy/action.

Media glucose concentrations above 5 mmol/L was associated with significant increase in breast cancer cell proliferation, clonogenicity, motility, upregulation/activation of pro-oncogenic signaling, and reduction in apoptosis. These effects were most significant in triple-negative breast cancer (TNBC) cell lines. High-glucose conditions (10 mmol/L or above) significantly abrogated the effects of metformin. Mechanisms of metformin action at normal vs. high glucose overlapped but were not identical; for example, metformin reduced IGF-1R expression in both the HER2+ SK-BR-3 and TNBC MDA-MB-468 cell lines more significantly at 5, as compared with 10 mmol/L glucose. Significant changes in gene profiles related to apoptosis, cellular processes, metabolic processes, and cell proliferation occurred with metformin treatment in cells grown at 5 mmol/L glucose, whereas under high-glucose conditions, metformin did not significantly increase apoptotic/cellular death genes. These data indicate that failure to maintain glucose homeostasis may promote a more aggressive breast cancer phenotype and alter metformin efficacy and mechanisms of action.     

Contributions of estrogen to ER-negative breast tumor growth

Breast cancer is a hormone-based disease with numerous factors contributing to the lifetime risk of developing the disease. While breast cancer risk is reduced by nearly 50% after one full term pregnancy, women over the age of 25 have a significantly greater risk of developing breast cancer immediately following parturition compared to their nulliparous counterparts. It is widely presumed that the increased risk of developing breast cancer following pregnancy is due to the ability of pregnancy-associated hormones to promote the further proliferation of an initiated target cell population. It is surprising however, that the majority of breast cancers that develop following pregnancy lack appreciable expression of either the estrogen or progesterone receptors. This important observation suggests that if hormones play a part in promoting breast cancer following pregnancy, they may not be doing so through direct binding to hormone receptor molecules expressed by breast cancer cells.

To reconcile this conceptual conflict we investigated the hypothesis that steroid hormones promote the outgrowth of ER-negative cancers by influencing host cell types distinct from the breast epithelium itself. We demonstrated that increasing the levels of circulating estrogens is sufficient to promote the formation and progression of ER-negative cancers while, pharmacologically inhibiting estrogen synthesis following pregnancy prevents ER-negative tumor formation. Moreover, we demonstrate that the effects of estrogen act via a systemic increase in host angiogenesis, in part through increased mobilization and recruitment of bone marrow stromal derived cells into sites of angiogenesis and to a growing tumor mass. Taken together, these data suggest that estrogen may promote the growth of ER-negative cancers by acting on cells distinct from the cancer cells to stimulate angiogenesis.     

长链非编码RNA RP11-214F16.8 促进乳腺癌细胞增殖

长链非编码RNAs (long non-coding RNAs, lncRNAs)在乳腺癌发生发展中的作用备受瞩目。本研究通过大数据分析发现,lncRNA RP11-214F16.8在乳腺癌组织中的表达量显著高于正常组织,且其表达量与乳腺癌患者预后负相关。因此,本文采用qRT-PCR技术,在收集的临床样本中验证RP11-214F16.8的表达,证实其在乳腺癌组织中相对表达量为5.65±0.72,其在癌旁组织中表达量为2.63±0.35,且RP11-214F16.8的表达量与乳腺癌瘤体大小和临床TNM分期相关。此外发现,RP11-214F16.8在乳腺癌细胞中的表达量高于正常乳腺上皮细胞。在乳腺癌MCF-7细胞中,过表达RP11-214F16.8后,MCF-7细胞的增殖能力显著增强。而在MDA-MB-231细胞中,敲低RP11-214F16.8的表达,获得相反的结果。进一步研究发现,RP11-214F16.8可上调细胞周期蛋白 D3、CDK4的表达,而下调p18蛋白表达量,进而加速细胞增殖。总之,RP11-214F16.8在乳腺癌中高表达,且促进乳腺癌细胞增殖,进而推动乳腺癌进程。这一研究发现,将为乳腺癌发生发展的网络机制研究提供新的理论依据。     

From milk to malignancy: the role of mammary stem cells in development, pregnancy and breast cancer

Adult stem cells of the mammary gland (MaSCs) are a highly dynamic population of cells that are responsible for the generation of the gland during puberty and its expansion during pregnancy. In recent years significant advances have been made in understanding how these cells are regulated during these developmentally important processes both in humans and in mice. Understanding how MaSCs are regulated is becoming a particularly important area of research, given that they may be particularly susceptible targets for transformation in breast cancer. Here, we summarize the identification of MaSCs, how they are regulated and the evidence for their serving as the origins of breast cancer. In particular, we focus on how changes in MaSC populations may explain both the increased risk of developing aggressive ER/PR(-) breast cancer shortly after pregnancy and the long-term decreased risk of developing ER/PR(+) tumors.     

Case-control study of fetal microchimerism and breast cancer

Background

Prior pregnancy is known to protect against development of breast cancer. Recent studies have demonstrated that pregnancy has the capacity to establish small numbers of immunologically active fetal-derived cells in the mother, a phenomenon known as fetal microchimerism (FMc). We asked whether presence of FMc, routinely acquired during pregnancy, is a protective factor for breast cancer.

Methodology/Principal Findings

DNA extracts from peripheral blood specimens were obtained from a population-based case-control study of risk factors for breast cancer in women 21 to 45 years old. Specimens were tested with quantitative PCR for presence and concentrations of male DNA presumed to derive from prior pregnancies with a male fetus. Odds ratios (OR) and 95% confidence intervals (CI) were estimated with consideration of multiple established reproductive and environmental risk factors for breast cancer. FMc results were generated on 99 parous women, 54 with primary invasive breast cancer and 45 general population controls. FMc prevalence was 56% (25/45) and 26% (14/54) in controls and cases, respectively. Women harboring FMc were less likely to have had breast cancer (OR = 0.29, 95% CI 0.11–0.83; p = 0.02, adjusting for age, number of children, birth of a son, history of miscarriage, and total DNA tested). In addition, FMc concentrations were higher in controls versus cases (p = 0.01). Median concentrations were 2 (0–78) and 0 (0–374) fetal genomes/10⁶ maternal genomes in controls and cases, respectively.

Conclusions

Results suggest that the enigma of why some parous women are not afforded protection from breast cancer by pregnancy might in part be explained by differences in FMc. Mechanistic studies of FMc-derived protection against breast cancer are warranted.     

M2 macrophages contribute to cell proliferation and migration of breast cancer

Breast cancer is a kind of malignant tumor that severely threatens women's lives and health worldwide. Tumor-associated macrophages (TAMs) have been reported to mediate tumor progression, while the mechanism still needs further identification. In this study, we found that M2 macrophages promoted increased cell proliferation and migration as well as reduced expression of interferon regulatory factor 7 (IRF7) and increased the expression of miR-1587 in breast cancer cells. Overexpression of IRF7 or miR-1587 knockdown reversed M2 macrophage-induced cell proliferation and migration as well as tumor growth in vivo. Mechanistically, miR-1587 targeted the 3ʹ-untranslated region (3ʹ-UTR) of IRF7 mRNA to regulate its protein expression leading to tumor progression. Collectively, this study revealed that the miR-1587/IRF7 axis mediates M2 macrophage-induced breast cancer progression, and this sheds light on further clinical therapy for breast cancer by targeting TAMs as well as the miR-1587/IRF7 axis.     

Nimbolide inhibits IGF‐I‐mediated PI3K/Akt and MAPK signalling in human breast cancer cell lines (MCF‐7 and MDA‐MB‐231)

The insulin‐like growth factor I (IGF‐I) signalling pathway contributes a major role on various cancer cell proliferation, survival and cell cycle. The present study was aimed to investigate the effect of nimbolide on IGF signalling and cell cycle arrest in MCF‐7 and MDA‐MB‐231 breast cancer cell lines. The protein expression of IGF signalling molecules and cell cycle protein levels was assessed by western blot analysis. In order to study the interaction of nimbolide on IGF‐1 signalling pathway, IGF‐I and phosphoinositide 3‐kinase (PI3K) inhibitor (LY294002) were used to treat MCF‐7 and MDA‐MB‐231 cells. Further, the cell cycle arrest was analysed by flow cytometry. The protein expression of IGF signalling molecules was significantly decreased in nimbolide‐treated breast cancer cells. PI3K inhibitor and IGF‐I with nimbolide treatment notably inhibited phosphorylated Akt. The cell cycle arrest was observed at the G0/G1 phase, and accumulation of apoptotic cells was observed in nimbolide‐treated breast cancer cell lines. Nimbolide also increased the protein expression of p21 and decreased the cyclins in both the cell lines. Nimbolide decreases the proliferation of breast cancer cells by modulating the IGF signalling molecules, which could be very useful for the breast cancer treatment. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of thyroid hormones on human breast cancer cell proliferation

The involvement of estrogens in breast cancer development and growth has been well established. However, the effects of thyroid hormones and their combined effects with estrogens are not well studied. We investigated the response of human breast cancer cells to thyroid hormone, particularly the role of T3 in mediating cell proliferation and gene expression. We demonstrated that 17β-estradiol (E2) or triiodothyronine (T3) promoted cell proliferation in a dose-dependent manner in both MCF-7 and T47-D cell lines. The E2- or T3-dependent cell proliferation was suppressed by co-administration of the ER antagonist ICI. We also demonstrated that T3 could enhance the effect of E2 on cell proliferation in T47-D cells. Using an estrogen response element (ERE)-mediated luciferase assay, we determined that T3 was able to induce the activation of ERE-mediated gene expression in MCF-7 cells, although the effects were much weaker than that induced by E2. These results suggest that T3 can promote breast cancer cell proliferation and increase the effect of E2 on cell proliferation in some breast cancer cell lines and thus that T3 may play a role in breast cancer development and progression.     

A novel biphenyl urea derivate inhibits the invasion of breast cancer through the modulation of CXCR4

The increased migration and invasion of breast carcinoma cells are key events in the development of metastasis to the lymph nodes and distant organs. CXCR4, the receptor for stromal‐derived factor‐1, is reportedly involved in breast carcinogenesis and invasion. In this study, we investigated a novel biphenyl urea derivate, TPD7 for its ability to affect CXCR4 expression as well as function in breast cancer cells. We demonstrated that TPD7 inhibited the breast cancer proliferation and down‐regulated the CXCR4 expression on breast cancer cells both over‐expressing and low‐expressing HER2, an oncogene known to induce the chemokine receptor. Treatments with pharmacological proteasome inhibitors partial suppressed TPD7‐induced decrease in CXCR4 expression. Real‐time PCR analysis revealed that down‐regulation of CXCR4 by TPD7 also occurred at the translational level. Inhibition of CXCR4 expression by TPD7 further correlated with the suppression of SDF‐1α‐induced migration and invasion in breast tumour cells, knockdown of CXCR4 attenuated TPD7‐inhibitory effects. In addition, TPD7 treatment significantly suppressed matrix metalloproteinase (MMP)‐2 and MMP‐9 expression, the downstream targets of CXCR4, perhaps via inactivation of the ERK signaling pathway. Overall, our results showed that TPD7 exerted its anti‐invasive effect through the down‐regulation of CXCR4 expression and thus had the potential for the treatment of breast cancer.     

SH3GL1在紫杉醇耐药乳腺癌中的表达及临床意义

膜结合蛋白SH3GL1参与调控某些肿瘤细胞生物学行为,而其对紫杉醇耐药乳腺癌细胞的恶性生物学行为影响尚未见报道.为阐明 SH3GL1对紫杉醇耐药敏感性的影响以及潜在的分子机制,本研究首先采用免疫组化法证实SH3GL1在紫杉醇耐药乳腺癌组织高表达(P<0.001).Western印迹法证实,SH3GL1在紫杉醇耐药细胞株MCF-7/PTX高表达(P<0.01);随后,采用MTT分别检测（0,50,100 nmol/L）紫杉醇处理后MCF-7细胞株增殖情况,同时Western印迹法检测SH3GL1表达,发现100 nmol/L紫杉醇能够抑制MCF-7细胞增殖(P<0.05);同时抑制SH3GL1表达(P<0.01); 敲减SH3GL1表达后,紫杉醇耐药细胞株MCF-7/PTX和MCF-7增殖速率降低(P<0.05),耐药基因MDR1表达降低(P<0.05),p-AKT和p-gp水平下降(P<0.05).上述结果表明,降低SH3GL1表达可以减弱紫杉醇耐药性,增加乳腺癌对紫杉醇的敏感性,这为临床上紫杉醇耐药乳腺癌患者的治疗提供了新的靶点.     

Prospective breast cancer risk factors prediction in Saudi women

Women's health is affected by breast cancer worldwide and Saudi Arabia (SA) is no exception. Malignancy has enormous consequences for social, psychological and public health. The aim of this study was to examine the risk factors for Saudi women from breast cancer using logistic regression models. In 135 patient cases for different stages of breast cancer was used to study case management, 270 healthy women from King Abd Alla Medical City, Mecca, SA were taken to predict the probability of women developing breast cancer, logistic regression was analyzed taking factors such as age, marital status, family history, parity, age at first full-term pregnancy, menopausal status, body mass index (BMI) and breast feeding. The logistic regression model showed that there are important risk factors (age, marital status, family history, parity, age at first full-term pregnancy, menopausal status, body mass index, and breast feeding) in development of breast cancer. Fewer cases were observed in unmarried women, age ≤30, BMI ≤20. In contrast, more cases were found with women age 41–50 married, BMI > 30, a smaller number of children, not breast feeding, age of first pregnancy ≥30, menopausal status age at 46–50. Based on our data there is role of risk factors in developing breast cancer, less BMI, the increase number of children, breast feeding, which are playing as protective factor for breast cancer.     

RNAi-mediated silencing of the Bmi-1 gene causes growth inhibition and enhances doxorubicin-induced apoptosis in MCF-7 cells

The oncogene Bmi-1 is a member of the Polycomb group gene family. Its expression is found to be greatly increased in a number of malignant tumors including breast cancer. This could suggest Bmi-1 as a potent therapeutic target. In this study, RNAi was introduced to down-regulate the expression of Bmi-1 in a highly malignant breast adenocarcinoma cell line, MCF-7. A thorough study of the biological behavior and chemosensitivity changes of the MCF-7 cells was carried out in context to the therapeutic potential of Bmi-1. The results obtained indicated that siRNA targeting of Bmi-1 could lead to an efficient and specific inhibition of endogenous Bmi-1 activity. The mRNA and protein expression of Bmi-1 were determined by RT-PCR and Western blot, respectively. Furthermore, silencing of Bmi-1 resulted in a drastic inhibition of the growth of MCF-7 cells as well as G(1) /S phase transition. The number of target cells was found to increase in phase G (0) /G (1) and decrease in the S phase, but no increase in the basal level of apoptosis was noticed. On the other hand, a reduction in the expression of cyclin D1 and an increase in the expression of p21 were also noticed. Silencing of Bmi-1 made the MCF-7 cells more sensitive to the chemotherapeutic agent doxorubicin and induced a significantly higher percentage of apoptotic cells. Here, we report on a study regarding the RNAi-mediated silencing of the Bmi-1 gene in breast cancer.