Normal Mammary Gland Cells Research Articles

Targeting the mTOR Pathway for the Prevention of ER-Negative Breast Cancer.

Our results show that everolimus delays mammary tumor formation in multiple mouse models, suggesting that mTOR inhibitors will be useful for the prevention of ER-negative and triple-negative breast cancer in humans. See related Spotlight, p. 787.

GPR30 expression and function in breast cancer cells are induced through a cis‑acting element targeted by ETS factors.

The capacity that G protein‑coupled receptor30 (GPR30) has demonstrated for triggering estrogen‑dependent signaling pathways has attracted the interest of breast cancer researchers; however, the reported expression profiles and functions of GPR30 in breast cancer are inconsistent. The main purpose of the present investigation was to identify transcriptional mechanisms underlying the expression of GPR30 that allow a better understanding of its role in breast cancer progression. In the cell lines used as different polarity models in the present study, it was determined immunologically that GPR30 is expressed in normal mammary gland cells and that this expression decreased considerably during breast cancer development, where cell identity is lost. However, it was also determined that, in spite of low GPR30 expression levels in breast cancer cells with little differentiation, this membrane estrogen receptor (ER) is able to increase cell viability and suppress migration in cells that have acquired metastatic capacity. In addition, through transient expression assays in breast cancer cells, it was revealed that a transcriptional mechanism dependent on protein kinase A and susceptible to retinoic acid in ER‑positive cells induces GPR30 expression through a cis‑regulatory element for E26 transformation‑specific transcription factors, located between ‑631 and ‑625bp from the GPR30 translation start codon. Overall, these results suggested that invitro transcriptional regulation of GPR30 expression in breast cancer cells may serve a relevant role in the conservation of an epithelial phenotype, and also may be important to avoid the transition to metastasis.

Long non‑coding RNA nuclear paraspeckle assembly transcript 1 interacts with microRNA‑107 to modulate breast cancer growth and metastasis by targeting carnitine palmitoyltransferase‑1.

Previous studies revealed that the long non‑coding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) exhibits abnormal expression in numerous cancer types, including breast cancer (BC); however, the regulatory mechanism of NEAT1 in BC remains unclear. In the present study, the effect of NEAT1 on the progression of BC and its regulation mechanism was investigated. The expression levels of NEAT1 and microRNA‑107 (miR‑107) in BC cells were analyzed using the reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). NEAT1 was knocked down in BC cells, and mimics‑miR‑107 or inhibitor‑miR‑107 were transfected into BC cells. Subsequently, cell proliferation, invasion and migration, apoptosis and cell cycle distribution were determined. The regulatory mechanism of NEAT1, miR‑107 and carnitine palmitoyltransferase‑1 (CPT1A) was analyzed using a luciferase reporter assay system, western blotting and RT‑qPCR. NEAT1 expression was increased in BC cells, whereas miR‑107 expression was decreased, compared with normal mammary gland cells. NEAT1 promoted the progression of BC cells through inhibiting apoptosis‑associated genes and promoting cell cycle‑ and invasion‑associated gene expression, whereas miR‑107 served the opposite function. Furthermore, NEAT1 promoted the expression of CPT1A, which was mediated by miR‑107. The results of the present study indicate that NEAT1 promotes the expression of CPT1A by inhibiting miR‑107 to improve the progression of BC cells; therefore, NEAT1 is a potential therapeutic target of BC.

ANXA1 inhibits miRNA-196a in a negative feedback loop through NF-kB and c-Myc to reduce breast cancer proliferation

MiRNAs are endogenous ~22 nt RNAs which play critical regulatory roles in a wide range of biological and pathological processes, which can act as oncogenes or tumor suppressor genes depending on their target genes. We have recently shown that ANXA1 inhibits the expression of miRNAs including miR196a. Here, we show that miR196a was highly expressed in ER+ MCF-7 breast cancer cells when compared to normal mammary gland cells, with expression levels negatively correlating to ANXA1. ANXA1 inhibits the biogenesis of oncogenic miR-196a by suppressing primary-miR196a indirectly through the stimulation of c-myc and NFkB expression and activity in breast cancer cells. In a negative feedback loop, miR-196a directly inhibits ANXA1 and enhances breast cancer cell proliferation in vitro. Finally, miR196a promotes breast tumor growth in vivo. This study reports a novel regulatory circuit between ANXA1, NF-kB, c-myc and miR-196a which regulates breast cancer cell proliferation and tumor growth.

Correlation of Forkhead Box c2 with subtypes and invasive ability of invasive breast cancer.

Forkhead Box c2 (FOXC2) is a member of forkhead/winged-helix family of transcription factors. The relationship between FOXC2 and invasive breast cancers, including basal-like breast cancer (BLBC, a subtype of breast cancer), remains to be elucidated. In this study, immunohistochemistry was used to detect the expression of FOXC2 in samples from 103 cases of invasive breast cancers and 15 cases of normal mammary glands. The relationship between FOXC2 and clinical parameters of invasive breast cancers such as patient's age, tumor size, lymph node metastasis, tumor grade, the expression of ER, PR, HER-2 and p53, and Ki-67 labeling index (LI) was evaluated. The expression of FOXC2 was detected in parent MCF7 cells, MCF cells transfected with FOXC2 expression vectors and MDA-MB-435 cells by immunohistochemistry and Western blotting. Transwell assay was used to determine the invasive ability of these cells. The results showed that FOXC2 was strongly expressed in basal epithelial cells in normal mammary glands and weakly expressed or even not expressed in glandular epithelial cells. The majority of invasive breast cancers (71.8%, 74/103) had negative or weak expression of FOXC2. However, FOXC2 was strongly expressed in 60.7% of BLBCs. Moreover, FOXC2 was related with tumor grade, p53 expression, ki-67 LI and lymph nodes metastasis. It was expressed in FOXC2-transfected MCF cells and MDA-MB-435 cells but not in parent MCF cells. Transwell assay revealed that MCF cells transfected with FOXC2 expression vectors were more aggressive than the parent MCF cells, suggesting a positive correlation between FOXC2 and the invasion of breast cancer. It was concluded that there is a significant association between FOXC2 and the metastasis of invasive breast cancer. FOXC2 may be used as a new marker for the diagnosis and prognosis prediction of different subtypes of invasive breast cancers.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Silencing MAP3K1 expression through RNA interference enhances paclitaxel-induced cell cycle arrest in human breast cancer cells

The objective of this study is to compare the expression level of MAP3K1 between normal mammary gland cells and breast cancer cells, and to analyze the effects of silencing MAP3K1 on breast cancer cells with paclitaxel treatment. Western blotting analysis was used to detect the expression level of MAP3K1 in MCF-7 and MCF-12F cells. The effect of gene silencing through different siRNAs was determined by realtime-PCR. MTT assay was used to test the cell proliferation. Cell cycle was detected by flow cytometry. MAP3K1 protein expression level in breast cancer cells was higher than that in normal mammary gland cells. MAP3K1 siRNA transfection significantly reduced the expression level of MAP3K1, and enhanced paclitaxel-induced cell proliferation inhibition and cell cycle arrest in breast cancer cells. Targeting MAP3K1 expression through small RNA interference can promote the therapeutic effects of paclitaxel in breast cancer.

L-Type Amino Acid Transporter 1 (LAT1) Expression in Canine Mammary Gland Tumors

L-type amino acid transporter 1 (LAT1), an isoform of amino acid transport system L, transports branched or aromatic amino acids essential for fundamental cellular activities such as cellular growth, proliferation and maintenance. This amino acid transporter recently has received attention because of its preferential and up-regulated expression in a variety of human tumors, in contrast to its limited distribution and low-level expression in normal tissues. In this study, to explore the feasibility of using LAT1 expression as a molecular marker in mammary gland tumors (MGT), we performed a comparative study of LAT1 expression at the mRNA and protein levels in normal mammary gland cells and tumor cells. Conventional RT-PCR and Western blotting were performed on MGT tissues from 16 dogs and normal organs from nine healthy dogs. LAT1 expression was detected in ten of the 16 MGT patients. As is the case in human tissues, LAT1 showed limited expressional distribution in normal canine organs. For quantitative expressional comparison, extensive real-time RT-PCR was performed on mRNA samples from 53 MGT patients. The comparison demonstrated that LAT1 mRNA levels from MGT tissues were 20 times higher than those in normal mammary gland tissues. Additionally, histologically invasive MGT showed a higher expression of LAT1 than non-invasive tumors. These findings suggest that LAT1 could be a clinical marker and therapeutic target for invasive malignant MGT.

96P Quantitative Proteomics Profiling of Murine Mammary Gland Cells Unravels Impact of Annexin-1 On Dna Damage, Cell Adhesion and Migration

ABSTRACT Modern mass spectrometry (MS)-based technology offers exciting strategies for advances in many areas of biology. Among the quantitative MS strategies, stable isotope labelling by amino acids in cell culture (SILAC) has emerged as a simple and robust approach to solve a wide range of biological problems. We employ this technology to understand the roles of Annexin-1 (ANXA1) that has been reported to be involved in important physio-pathological implications including cell proliferation, differentiation, apoptosis, cancer and metastasis. However, with controversies in ANXA1 expression in breast carcinomas, its role in breast cancer initiation and progression remains unclear. In this study, we perform quantitative comparison of the proteomes of normal mammary gland cells from ANXA1 heterozygous (ANXA1+/-) and null (ANXA1-/-) mice using SILAC. Among over 4000 quantified proteins, we observe 214 up-regulated and 169 down-regulated in ANXA1-/-. Bioinformatics analysis of the up-regulated proteins reveals that ANXA1 is potentially implicated in DNA damage and apoptosis, whereas the analysis of down-regulated proteins shows ANXA1's possible roles in cell adhesion and migration pathways. Results of relevant functional assays further support the bioinformatics analysis. Among them, the Comet assay demonstrates that ANXA1-/- cells accumulates more DNA damage with slower recovery as compared to the ANXA1+/- after heat stress. Both migration and wound healing assays show that ANXA1+/- cells possess higher motility with better wound closure capability than the ANXA1-/- . Our quantitative proteomics data together with functional analysis strongly suggest that ANXA1 plays a protective role in DNA damage and modulates cell adhesion and motility, demonstrating its potential role in cancer initiation as well as progression in breast carcinoma. Disclosure All authors have declared no conflicts of interest.

Tamoxifen and Melatonin Differentially Influence Apoptosis of Normal Mammary Gland Cells: Ultrastructural Evidence and p53 Expression

Tamoxifen and Melatonin Differentially Influence Apoptosis of Normal Mammary Gland Cells: Ultrastructural Evidence and p53 Expression

Evaluation of chromogranin A expression in serum and tissues of breast cancer patients.

Human chromogranin A (CgA) is a member of the granin family and is widely distributed in large dense core granules of endocrine and neuroendocrine cells. A variety of non-neuroendocrine carcinomas arising in various tissues show patterns of neuroendocrine differentiation. Expression of CgA has been documented in epithelial cells of normal mammary gland as well as in breast cancers, and elevation of serum CgA has been detected in patients with breast cancer. Our study was undertaken to evaluate the relationship between serum CgA levels and neuroendocrine features in breast cancer. In addition, we evaluated the expression of serum CgA in patients affected by breast cancer compared to controls and the relationship between serum CgA and tumor histology, extent of disease, lymph node status, tumor stage and serum CA 15.3 levels. We enrolled 266 patients with infiltrating ductal or lobular breast carcinoma and a group of 100 age-matched healthy women serving as controls. Serum CgA and CA 15.3 were assayed by specific immunoradiometric methods. The overall sensitivity of CgA and CA 15.3 was 0.06 and 0.34, respectively (chi2 19.1, p<0.0005). No relationship was found between serum levels of CgA and tumor histology, extent of disease, lymph node status or tumor stage while serum levels of CA 15.3 were strongly correlated with all these variables but tumor histology. No relationship was found between serum levels of CgA and CA 15.3. Immunostaining against CgA, CgB, NSE and synaptophysin was performed on primary tumor tissue of 14 serum CgA-positive and 24 serum CgA-negative patients and was negative in all cases. We also evaluated eight cases of pathologically-proven neuroendocrine breast cancer: only four and two of these showed positive CgA immunostaining and increased serum CgA concentration, respectively. In conclusion, serum CgA assay offers no additional information regarding the presence, the extent and the histology of breast cancer compared to the CA 15.3 assay. Moreover, serum CgA was not an accurate marker to identify or exclude the rare neuroendocrine differentiation of breast cancer. We therefore conclude that CgA is not useful as a serum marker in breast cancer.

Activation of the estrogen-signaling pathway by p21(WAF1/CIP1) in estrogen receptor-negative breast cancer cells.

Estrogen stimulates the proliferation of cells in normal mammary glands and most estrogen receptor (ER)-positive mammary carcinomas by binding to the ER and promoting the transcription of ER-responsive genes. In cells with functional ERs, estrogen mediates the transition of cells from the G(1) to S phase of the cell cycle. Several cell cycle regulatory proteins have been implicated in the ER-signaling pathway involved in estrogen-mediated growth stimulation and antiestrogen-mediated growth arrest. We sought to determine whether p21, a cyclin-dependent kinase inhibitor, is a component of this pathway and, if so, whether it can mediate estrogen's action in ER-negative breast cancer cells. We overexpressed p21 with a tetracycline-inducible system in ER-negative, p21-negative breast cancer cells. Activity of the ER-signaling pathway was monitored in transient transfection assays by using constructs in which the ER promoter or the estrogen-response element (ERE) controls Luciferase expression. The growth-modulating effects of estradiol and antiestrogens on p21-overexpressing clones were assessed. All P: values are from two-sided tests. A strong positive association was found between the expression of p21 and ER in nine breast cancer cell lines and in tumor samples from 60 patients with breast cancer (P:<. 001). Overexpression of p21 in a p21-negative, ER-negative cell line induced both the ER and ERE promoters in an estrogen-responsive manner. Last, stable p21 clones that also lack the expression of wild-type ER were responsive to the growth-inhibitory effects of ICI 182,780, a potent antiestrogen, and the growth-stimulatory effects of 17beta-estradiol. The ability of p21 to mediate the activation of the estrogen-signaling pathway in ER-negative tumor cells suggests that p21 plays a novel role in this pathway, a finding that also has important clinical implications.

Chemoprevention by nimesulide, a selective cyclooxygenase-2 inhibitor, of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary gland carcinogenesis in rats.

Breast cancer is common in women all over the world, and exploration of chemopreventive approaches to this cancer is very important. Nimesulide, a selective inhibitor of cyclooxygenase‐2 (COX‐2), is a good candidate as a chemopreventive agent with low toxicity. We examined its effects on mammary tumor development in female Sprague‐Dawley rats induced with the environmental carcinogen 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP). Rats at 7 weeks of age received intragastric intubations of PhIP (85 mg/kg body weight) 4 times weekly for 2 weeks and were maintained on control diet (high fat diet) or experimental diet (high fat diet supplemented with 400 ppm nimesulide) throughout the experiment. COX‐2 protein was over‐expressed in epithelial cancer cells and stromal cells of the PhIP‐induced mammary carcinomas, but was weak or not apparent in normal mammary gland cells. The development of mammary carcinomas was clearly suppressed by administration of nimesulide. The carcinoma incidence was 51% as compared to 71% for the control diet group. The average multiplicity of carcinomas in the experimental diet group was 1.2±0.2 (P < 0.05), significantly smaller than the control diet group value (2.6±0.5). The size of carcinomas was also clearly decreased; 1.1±0.4 cm3/rat in experimental diet group (P < 0.05), 4.1±1.3 cm3/rat in the control diet group. The results therefore provide evidence that the selective COX‐2 inhibitor, nimesulide, possesses chemopreventive activity against PhIP‐induced mammary carcinogenesis in rats.

Etoposide enhances the lethal effect of radiation on breast cancer cells with less damage to mammary gland cells.

In the present study, the cytotoxic effects of anticancer drug treatment plus radiation on breast cancer and normal mammary gland cells were investigated in vitro. Breast cancer and adjacent mammary gland tissue was obtained from surgically resected specimens from 13 premenopausal female patients, and was cultured. Cultured cells were treated with radiation and etoposide, and sensitivities were evaluated using an MTT assay. In breast cancer cells, radiation alone had a cytotoxic effect. When etoposide was added, synergistic effects were achieved which were independent of the radiation dose. The cytotoxicity of etoposide against normal gland cells, however, was much the same as that against cancer cells, and no synergistic effects were observed in normal cells even when radiation was added. Radiation combined with etoposide showed lethal effects against breast cancer cells with less damage to normal mammary gland cells.

Progression of PDMT is accompanied by lack of Fas and intense expression of Bcl-2 and PKC-epsilon.

Recent study has demonstrated the development of pregnancy-dependent mammary tumors (PDMTs) in GR/A mice during pregnancy and their regression by apoptotic cell death after parturition. In the present study, we examined the molecular machinery of PDMTs before and after parturition and in progression. The death associated-cell surface molecule Fas was expressed only when apoptosis occurred, and no expression could be determined after progression. Interestingly, death suppressor Bcl-2 showed down-regulation when apoptosis occurred, and intense expression after progression. Examination of the possible involvement of PKC isozymes showed that only PKC-epsilon showed drastic changes in expression: expression was not detected in normal mammary gland cells and PDMTs, but was instead seen only when PDMTs progressed to malignant tumors. On the basis of these results, we suggest that PDMT-regression is due to Fas-mediated apoptosis, and that lack of Fas, persistent expression of Bcl-2, and new expression of PKC-epsilon are essential events for tumor progression.

Absence of neuroendocrine cells in fetal and adult mammary glands. Are neuroendocrine breast tumours real neuroendocrine tumours?

Abstract Some human breast carcinomas show features of neuroendocrine differentiation. The histogenesis of these tumours is debated especially because of the difficulty in locating neuroendocrine cells in normal mammary glands. The aim of this study was to search for neuroendocrine cells in two series of adult and fetal normal mammary glands. Eight female fetus breasts of gestational age between 24 and 37 weeks and 27 cases of normal adult breast tissues were investigated. Paraffin sections of formalin fixed samples were studied by Grimelius stain and immunohistochemistry using the monoclonal antibody anti-chromogranin A. An ultrastructural study was performed on a fetal mammary gland at the 37th week of gestation. Our results showed no histochemical, immunohistochemical and ultrastructural evidence of neuroendocrine differentiation in normal cells of fetal and adult mammary glands. The absence of neuroendocrine cells during mammary gland development indicates that the neuroendocrine part of a mammary cancer does not originate from a normal counterpart but that it is the result of a neuroendocrine differentiation during neoplastic progression.

Immunohistochemical detection of keratin, actin and type IV collagen in serial sections of methacarn-fixed breast cancer tissues.

Correlations among the immunolocalizations of keratin, actin and type IV collagen were investigated in serial sections of methacarn-fixed, paraffin-embedded mastectomy specimens taken from infiltrating breast cancer patients. Stainings of the filaments in pretreated sections with actinase were often weaker and/or less apparent in cancer cells than in normal mammary gland cells. If at least 30% of living cancer cells were stained, the case was scored positive. Positivity for 312C8-1 specific for basal cell type keratin 14 was observed in 8 of 60 cases, while for NCL-5D3 specific for luminal cell type keratins, positivity was observed in 57 of 60 cases. Five cases positive for HHF35 specific for muscle actin were also positive for 312C8-1 and NCL-5D3. Type IV collagen in cancer foci was patchy and/or absent, but small cancer nests surrounded completely by continuous type IV collagen, termed “in situ carcinoma components” were found in 25 of 60 cases. In all the components, stainings with 312C8-1 and/or NCL5D3 were found in some cancer cells, and the former was almost always seen in a basal orientation within the components. In con- clusion, keratin 14-positive basal cells could be identified in paraffin sections, and these findings suggest that the basal cells are closely related to continuous type IV collagen and a progressive loss of the cells may promote metastasis through fragmented type IV collagen.

Differential diagnosis of benign epithelialproliferations and carcinomas of the breast using antibodies to cytokeratins

The immunohistochemical reactivity on frozen sections of diverse benign and malignant epithelial proliferations of human breast tissue from 156 patients was examined using antibodies to different cytokeratins. Antibodies recognizing cytokeratins 18 and 19 reacted with luminal epithelial cells but not with myoepithelial cells of normal mammary gland, cystic disease, adenosis, papilloma, and fibroadenoma or with a subpopulation of proliferating cells in sclerosing adenosis and epitheliosis. These antibodies reacted with the tumor cells of all in situ and invasive carcinomas. KA1 antibody, which by one- and two-dimensional gel electrophoresis and immunoblotting was shown to bind preferentially to cytokeratin 14 in a complex with cytokeratin 5, reacted with the nonproliferating myoepithelium of normal gland, cystic disease, adenosis, papilloma, fibroadenoma, and in situ carcinoma; it also reacted with a subpopulation of proliferating cells in sclerosing adenosis and epitheliosis (papillomatosis) but was negative with the tumor cells of all preinvasive and most invasive carcinomas. In adenotic and epitheliotic proliferations, groups of cells were identified that reacted strongly with KA1 antibody in addition to antibodies to cytokeratins 18 and 19. The data are discussed with respect to epithelial cell heterogeneity in the breast. We show that by using such antibodies, benign epithelial proliferations are clearly distinguished from carcinomas.

Metabolic cooperation in vitro: Differential ability of ouabain to uncouple normal, preneoplastic, and neoplastic mouse mammary cells

We utilized two assays for metabolic cooperation in vitro , one in which cells were grown in monolayer and one in which the cells formed three-dimensional structures in a collagen gel matrix. Both assays required one of the test cell pair to be resistant both to ouabain and to thioguanine (deficient in hypoxanthine-guanine phosphoribosyltransferase). Normal mammary gland cells, cells from preneoplastic mouse hyperplastic alveolar nodules, and mouse mammary tumor cells were metabolically linked in vitro to the drug-resistant tumor cells. Ouabain abrogated communication between tumor cells and normal mammary gland cells and between tumor cells and preneoplastic cells but had no effect on communication between tumor cells.

Intranuclear dynamics of DNA polymerase α differs between the transplanted R3230AC mammary adenocarcinomas and the host mammary gland depending on lactation cycle

DNA polymerase α activity was markedly higher in all nuclear subfractions, including nuclear matrix, from transplanted R3230AC mammary adenocarcinomas than in the analogous fractions from mammary gland of same tumor-bearing pregnant or lactating rats. Changes in host lactational status had no significant effect on subnuclear distribution of tumor DNA polymerase α activity, with the majority (60–75%) localized in soluble nucleoplasm and a significant amount (13–20%) retained in the nuclear matrix. In the host mammary gland, nuclear matrix-bound DNA polymerase α was highest, accounting for 48% of total nuclear activity, during late pregnancy when mammary cells undergo rapid raplication. During lactation, when cells in mammary gland cease to divide, only 8% of enzyme activity was in the nuclear matrix, while the majority (60–80%) of DNA polymerase α activity was localized in nucleoplasm. In both R3230AC tumor and mammary gland regardless of host's lactational status, the majority (60–80%) of DNA polymerase β activity was localized in the high salt-soluble chromatin. These present data thus suggest that, regardless of host lactational status, R3230AC tumor has many cycling cells, each with a large pool of DNA polymerase α molecules maintaining maximal and constant replicative activity, while normal mammary gland cells have a smaller pool of DNA polymerase α which become primarily matrix-bound only during active cell replication during late pregnancy. A constant localization of nuclear DNA polymerase β in chromatin in both mammary gland and the tumor suggest it is not important in mammary cell proliferation.