PDGFRα and ß play critical roles in mediating Foxq1-driven breast cancer stemness and chemoresistance.

Many epithelial-mesenchymal transition (EMT)-promoting transcription factors have been implicated in tumorigenesis and metastasis as well as chemoresistance of cancer. However, the underlying mechanisms mediating these processes are unclear. Here, we report that Foxq1, a forkhead box-containing transcription factor and EMT-inducing gene, promotes stemness traits and chemoresistance in mammary epithelial cells. Using an expression profiling assay, we identified Twist1, Zeb2, and PDGFRα and ß as Foxq1 downstream targets. We further show that PDGFRα and ß can be directly regulated by Foxq1 or indirectly regulated through the Foxq1/Twist1 axis. Knockdown of both PDGFRα and ß results in more significant effects on reversing Foxq1-promoted oncogenesis in vitro and in vivo than knockdown of either PDGFRα or ß alone. In addition, PDGFRß is a more potent mediator of Foxq1-promoted stemness traits than PDGFRα. Finally, pharmacologic inhibition or gene silencing of PDGFRs sensitizes mammary epithelial cells to chemotherapeutic agents in vitro and in vivo. These findings collectively implicate PDGFRs as critical mediators of breast cancer oncogenesis and chemoresistance driven by Foxq1, with potential implications for developing novel therapeutic combinations to treat breast cancer.

Metabotropic glutamate receptor-1 contributes to progression in triple negative breast cancer.

TNBC is an aggressive breast cancer subtype that does not express hormone receptors (estrogen and progesterone receptors, ER and PR) or amplified human epidermal growth factor receptor type 2 (HER2), and there currently exist no targeted therapies effective against it. Consequently, finding new molecular targets in triple negative breast cancer (TNBC) is critical to improving patient outcomes. Previously, we have detected the expression of metabotropic glutamate receptor-1 (gene: GRM1; protein: mGluR1) in TNBC and observed that targeting glutamatergic signaling inhibits TNBC growth both in vitro and in vivo. In this study, we explored how mGluR1 contributes to TNBC progression, using the isogenic MCF10 progression series, which models breast carcinogenesis from nontransformed epithelium to malignant basal-like breast cancer. We observed that mGluR1 is expressed in human breast cancer and that in MCF10A cells, which model nontransformed mammary epithelium, but not in MCF10AT1 cells, which model atypical ductal hyperplasia, mGluR1 overexpression results in increased proliferation, anchorage-independent growth, and invasiveness. In contrast, mGluR1 knockdown results in a decrease in these activities in malignant MCF10CA1d cells. Similarly, pharmacologic inhibition of glutamatergic signaling in MCF10CA1d cells results in a decrease in proliferation and anchorage-independent growth. Finally, transduction of MCF10AT1 cells, which express c-Ha-ras, using a lentiviral construct expressing GRM1 results in transformation to carcinoma in 90% of resultant xenografts. We conclude that mGluR1 cooperates with other factors in hyperplastic mammary epithelium to contribute to TNBC progression and therefore propose that glutamatergic signaling represents a promising new molecular target for TNBC therapy.

Exercise dose, exercise adherence, and associated health outcomes in the TIGER study.

PURPOSE: To effectively evaluate activity-based interventions for weight management and disease risk reduction, objective and accurate measures of exercise dose are needed. This study examined cumulative exercise exposure defined by HR-based intensity, duration, and frequency as a measure of compliance with a prescribed exercise program and a predictor of health outcomes. METHODS: One thousand one-hundred fifty adults (21.3 ± 2.7 yr) completed a 15-wk exercise protocol consisting of 30 min·d, 3 d·wk, at 65%-85% maximum HR reserve. Computerized HR monitor data were recorded at every exercise session (33,473 valid sessions). To quantify total exercise dose, duration for each session was adjusted for average exercise intensity (%HR reserve) to create a measure of intensity minutes for each workout, which were summed over all exercise sessions to formulate an HR physical activity score (HRPAS). Regression analysis was used to examine the relation between HRPAS and physiological responses to exercise training. Compliance with the exercise protocol based on achievement of the minimum prescribed HRPAS was compared with adherence defined by attendance. RESULTS: On the basis of HRPAS, 868 participants were empirically defined as compliant, and 282 were noncompliant. HRPAS-based and attendance-based classifications of compliance and adherence differed in approximately 9% of participants. Higher HRPAS was associated with significant positive changes in body mass (P < 0.001), body mass index (P < 0.001), waist and hip circumferences (P < 0.001), percent body fat (P < 0.001), systolic blood pressure (P < 0.011), resting HR (P < 0.003), fasting glucose (P < 0.001), and total cholesterol (P < 0.02). Attendance-based adherence was associated with body mass, hip circumference, percent body fat, resting HR, and cholesterol (P < 0.05). CONCLUSIONS: The HRPAS is a quantifiable measure of exercise dose associated with improvement in health indicators beyond that observed when adherence is defined as session attendance.

Antagonists of anaphase-promoting complex (APC)-2-cell cycle and apoptosis regulatory protein (CARP)-1 interaction are novel regulators of cell growth and apoptosis.

CARP-1/CCAR1, a perinuclear phosphoprotein, is a regulator of cell growth and apoptosis signaling. Although CARP-1 is a regulator of chemotherapy-dependent apoptosis, it is also a part of the NF-κB proteome and a co-activator of steroid/thyroid nuclear receptors as well as ß-catenin signaling. Our yeast two-hybrid screen revealed CARP-1 binding with the anaphase-promoting complex/cyclosome E3 ubiquitin ligase component APC-2 protein. CARP-1 also binds with anaphase-promoting complex/cyclosome co-activators Cdc20 and Cdh1. Following mapping of the minimal epitopes involved in CARP-1 binding with APC-2, a fluorescence polarization assay was established that indicated a dissociation constant (K(d)) of 480 nm for CARP-1/APC-2 binding. Fluorescence polarization assay-based high throughput screening of a chemical library yielded several small molecule antagonists of CARP-1/APC-2 binding, termed CARP-1 functional mimetics. CFM-4 (1(2-chlorobenzyl)-5'-phenyl-3'H-spiro[indoline-3,2'-[1,3,4]thiadiazol]-2-one), a lead compound, binds with and stimulates CARP-1 expression. CFM-4 prevents CARP-1 binding with APC-2, causes G(2)M cell cycle arrest, and induces apoptosis with an IC(50) range of 10-15 µm. Apoptosis signaling by CFM-4 involves activation of caspase-8 and -9 and caspase-mediated ubiquitin-proteasome pathway-independent loss of cyclin B1 and Cdc20 proteins. Depletion of CARP-1, however, interferes with CFM-4-dependent cell growth inhibition, activation of caspases, and apoptosis. Because CFM-4 also suppresses growth of drug-resistant human breast cancer cells without affecting the growth of human breast epithelial MCF-10A cells, elevating CARP-1 by CFM-4 and consequent apoptosis could in principle be exploited to further elucidate, and perhaps effectively target, often deregulated cell cycle pathways in pathological conditions, including cancer.

Engagement of I-branching {beta}-1, 6-N-acetylglucosaminyltransferase 2 in breast cancer metastasis and TGF-{beta} signaling.

In this study, we have showed that GCNT2, a gene-encoding glucosaminyl (N-acetyl) transferase 2, I-branching enzyme, is overexpressed in highly metastatic breast cancer cell lines of human and mouse origin and basal-like breast tumor samples. GCNT2 expression is also significantly correlated to the metastatic phenotype in breast tumor samples. Functional studies showed that ectopic expression of GCNT2 enhances cell detachment, adhesion to endothelial cells, cell migration and invasion in vitro, and lung metastasis of breast cancer cells in vivo. Knockdown of GCNT2 expression decreases cell migration and invasion in vitro and lung metastasis in vivo. We have further shown the involvement of GCNT2 in the epithelial-to-mesenchymal transition (EMT). Specifically, the expression of E-cadherin is significantly changed upon GCNT2 expression at the protein level but not at the RNA level. Moreover, we have shown that GCNT2 is a direct target of the TGF-ß-smad pathway and that change in GCNT2 expression modulates EMT induced by TGF-ß1 treatment. Finally, we have shown that diminution of the glycosyltransferase activity of I-branching ß-1, 6-N-acetylglucosaminyl transferase 2 (GCNT2) abrogates its cell migration and invasion-promoting function and synergistic effect with TGF-ß to induce EMT. Our study for the first time showed that GCNT2 is a novel gene contributing to breast cancer metastasis with preferential expression in basal-like breast cancer. Moreover, we discovered that involvement of GCNT2 in EMT and TGF-ß signaling, and further glycosylation modification of E-cadherin by GCNT2, are the underlying integrative mechanisms for breast cancer metastasis, implying that blocking TGF-ß/GCNT2 signaling is a promising approach for targeting metastatic breast cancer.

p38γ mitogen-activated protein kinase contributes to oncogenic properties maintenance and resistance to poly (ADP-ribose)-polymerase-1 inhibition in breast cancer.

p38γ MAPK, one of the four members of p38 mitogen-activated protein kinases (MAPKs), has previously been shown to harbor oncogenic functions. However, the biologic function of p38γ MAPK in breast cancer has not been well defined. In this study, we have shown that p38γ MAPK is overexpressed in highly metastatic human and mouse breast cancer cell lines and p38γ MAPK expression is preferentially associated with basal-like and metastatic phenotypes of breast tumor samples. Ectopic expression of p38γ MAPK did not lead to an increase in oncogenic properties in vitro in most tested mammary epithelial cells. However, knockdown of p38γ MAPK expression resulted in a dramatic decrease in cell proliferation, colony formation, cell migration, invasion in vitro and significant retardation of tumorigenesis, and long-distance metastasis to the lungs in vivo. Moreover, knockdown of p38γ MAPK triggered the activation of AKT signaling. Inhibition of this feedback loop with various PI3K/AKT signaling inhibitors facilitated the effect of targeting p38γ MAPK. We further found that overexpression of p38γ MAPK did not promote cell resistance to chemotherapeutic agents doxorubicin and paclitaxel but significantly increased cell resistance to PJ-34, a DNA damage agent poly (ADP-ribose)-polymerase-1 (PARP) inhibitor in vitro and in vivo. Finally, we identified that p38γ MAPK overexpression led to marked cell cycle arrest in G(2)/M phase. Our study for the first time clearly demonstrates that p38γ MAPK is a promising target for the design of targeted therapies for basal-like breast cancer with metastatic characteristics and for overcoming potential resistance against the PARP inhibitor.

Forkhead transcription factor foxq1 promotes epithelial-mesenchymal transition and breast cancer metastasis.

Epithelial-mesenchymal transition (EMT) promotes cancer invasion and metastasis, but the integrative mechanisms that coordinate these processes are incompletely understood. In this study, we used a cross-species expression profiling strategy in metastatic cell lines of human and mouse origin to identify 22 up-regulated and 12 down-regulated genes that are part of an essential genetic program in metastasis. In particular, we identified a novel function in metastasis that was not previously known for the transcription factor Forkhead Box Q1 (Foxq1). Ectopic expression of Foxq1 increased cell migration and invasion in vitro, enhanced the lung metastatic capabilities of mammary epithelial cells in vivo, and triggered a marked EMT. In contrast, Foxq1 knockdown elicited converse effects on these phenotypes in vitro and in vivo. Neither ectopic expression nor knockdown of Foxq1 significantly affected cell proliferation or colony formation in vitro. Notably, Foxq1 repressed expression of the core EMT regulator E-cadherin by binding to the E-box in its promoter region. Further mechanistic investigation revealed that Foxq1 expression is regulated by TGF-ß1, and that Foxq1 knockdown blocked TGF-ß1-induced EMT at both morphological and molecular levels. Our findings highlight the feasibility of cross-species expression profiling as a strategy to identify metastasis-related genes, and they reveal that EMT induction is a likely mechanism underlying a novel metastasis-promoting function of Foxq1 defined here in breast cancer.

Suppression of breast xenograft growth and progression in nude mice: implications for the use of orally administered sphingolipids as chemopreventive agents against breast cancer.

Sphingolipids are lipid messengers involved in the regulation of many different cellular processes. Sphingolipid enzymes and bioactive metabolites have been targets of in vitro and in vivo efforts to suppress cancer growth, progression and metastasis of various cancer types. Dietary sphingomyelin effectively suppressed colon cancer in several rodent models without causing toxic side effects. In the present study, we determined if the effect of sphingolipid metabolites derived from the hydrolysis of dietary sphingomyelin is restricted to the intestinal tract or if their systemic concentrations are sufficient to suppress cancers of distant sites. For these studies, we used MCF10AT1 cells, a model for progressive breast cancer, injected into the mammary fatpad of nude mice as a single cell suspension. The mice were fed 0.1% sphingomyelin supplements in a semi-purified AIN76A control diet when the lesions were palpable. The study was terminated when the first lesions had grown to 5 mm. In the sphingomyelin-fed group, there was a trend to smaller lesion size and, importantly, a delayed progression to more malignant stages without apparent side effects. This may be the result of significantly reduced rates of proliferation and angiogenesis, while no increase of apoptosis was detected. Changes in aberrantly expressed proteins in the sphingomyelin-fed group, such as E-cadherin, VEGF and sphingosine kinase-1, may be associated with the suppression of tumor growth. These results demonstrate that diet-derived sphingolipids can efficiently suppress the growth and progression of MCF10AT1 xenografts, suggesting that dietary sphingomyelin may also be effective against cancers of other sites.

Expression of estrogenicity genes in a lineage cell culture model of human breast cancer progression.

TaqMan Gene Expression assays were used to profile the mRNA expression of estrogen receptor (ERalpha and ERbeta) and estrogen metabolism enzymes including cytosolic sulfotransferases (SULT1E1, SULT1A1, SULT2A1, and SULT2B1), steroid sulfatase (STS), aromatase (CYP19), 17beta-hydroxysteroid dehydrogenases (17betaHSD1 and 2), CYP1B1, and catechol-O-methyltransferase (COMT) in an MCF10A-derived lineage cell culture model for basal-like human breast cancer progression and in ERalpha-positive luminal MCF7 breast cancer cells. Low levels of ERalpha and ERbeta mRNA were present in MCF10A-derived cell lines. SULT1E1 mRNA was more abundant in confluent relative to subconfluent MCF10A cells, a non-tumorigenic proliferative breast disease cell line. SULT1E1 was also expressed in preneoplastic MCF10AT1 and MCF10AT1K.cl2 cells, but was markedly repressed in neoplastic MCF10A-derived cell lines as well as in MCF7 cells. Steroid-metabolizing enzymes SULT1A1 and SULT2B1 were only expressed in MCF7 cells. STS and COMT were widely detected across cell lines. Pro-estrogenic 17betaHSD1 mRNA was most abundant in neoplastic MCF10CA1a and MCF10DCIS.com cells, while 17betaHSD2 mRNA was more prominent in parental MCF10A cells. CYP1B1 mRNA was most abundant in MCF7 cells. Treatment with the histone deacetylase inhibitor trichostatin A (TSA) induced SULT1E1 and CYP19 mRNA but suppressed CYP1B1, STS, COMT, 17betaHSD1, and 17betaHSD2 mRNA in MCF10A lineage cell lines. In MCF7 cells, TSA treatment suppressed ERalpha, CYP1B1, STS, COMT, SULT1A1, and SULT2B1 but induced ERbeta, CYP19 and SULT2A1 mRNA expression. The results indicate that relative to the MCF7 breast cancer cell line, key determinants of breast estrogen metabolism are differentially regulated in the MCF10A-derived lineage model for breast cancer progression.

Increased production and secretion of HGF alpha-chain and an antagonistic HGF fragment in a human breast cancer progression model.

Invasive human breast carcinomas frequently coexpress increased hepatocyte growth factor (HGF) and its receptor Met, suggesting that establishment of an autocrine HGF loop is important in malignant disease. This study examines the expression patterns of HGF and Met activation during tumorigenesis and metastasis using a MCF10A-based model of Ha-Ras-induced human breast cancer progression. Deregulation of cadherin-based cell-cell adhesions, decreased expression of cytokeratins 8/18 and increased activity of matrix metalloproteinases such as MMP-2 occurs in premalignant and malignant (metastatic) cell lines compared to the parental nonmalignant cell line. Compared to the benign parent cell line, premalignant and malignant cell lines exhibit increased secretion of full length HGF alpha-chain and elevated Met tyrosine phosphorylation in complete medium. Interestingly, the premalignant and malignant cells also secrete a approximately 55 kDa HGF fragment. Epitope mapping of the approximately 55 kDa HGF fragment supports the presence of the N-terminal domain of the HGF alpha-chain with a truncation in the C-terminal domain. The approximately 55 kDa HGF fragment shows mobility in SDS-PAGE faster than HGF alpha-chain, but slightly slower than NK4, a previously established full antagonist of HGF. The separated approximately 55 kDa HGF fragment binds to animmobilized Met-IgG fusion protein, and inhibits both HGF/Met-IgG binding and HGF-induced Met-tyrosine phosphorylation. These results are the first demonstration of an antagonistic approximately 55 kDa HGF fragment secreted during breast carcinoma progression, which may have a negative regulatory effect on HGF signaling in premalignant breast epithelial cells.

Proteomic and phosphoproteomic alterations in benign, premalignant and tumor human breast epithelial cells and xenograft lesions: biomarkers of progression.

The MCF10A human breast epithelial cell lineage includes the benign MCF10A cells, premalignant cells (MCF10AT, MCF10ATG3B) and malignant MCF10CA1a tumor cells. The premalignant and tumor cells recapitulate the progressive alterations associated with the temporal development of PBD and carcinoma. Ras protein levels were elevated by 6.9-, 22.4- and 32.2-fold in 10AT, 10ATG3B and 10CA1a cells, respectively, relative to 10A cells. K-Ras was not detected, N-Ras levels were unchanged; Rac and Rho levels increased in 10CA1a tumor cells. Phospho-phosphatidylinositol 3-kinase, phosphoinositide-dependent protein kinase 1 (PDK1), phospho-PDK1, phospho-eukaryotic translation initiation factor 4E (eIF4E) and phospho-eukaryotic initiation factor 4E binding protein 1 (4E-BP1) levels progressively increased in the cell lineage, with the greatest increase monitored in 10CA1a tumor cells. Phospho Ser 473 and Thr 408 Akt levels increased 10.2- and 136-fold in 10CA1a cells, respectively, relative to 10A cells. Phospho-p70S6 kinase (p70S6K) increased >2-fold in 10CA1a cells, relative to 10A cells. Immunohistochemistry confirmed Ras, phospho-Akt and phospho-p70S6K (Thr 421/ Ser 424) expression in lesions arising from premalignant and tumor cells. FOXO 1, phospho-FOXO 1 and phospho-FOXO 4 were significantly elevated in 10ATG3B premalignant and 10CA1a tumor cells. Phospho-FOXO 3a was progressively elevated, with the greatest levels detected in 10CA1a tumor cells. Immunohistochemistry revealed that phospho-FOXO 1, 3a and 4 staining was less in benign lesions, but elevated in advanced 10ATG3B and malignant 10CA1a lesions, showing a correspondence between the cells and lesions. Hence, phospho-Akt and phospho-FOXO 1, 3a and 4 merit consideration as biomarkers of tumorigenic risk from hyperplastic breast tissue.

Genome based cell population heterogeneity promotes tumorigenicity: the evolutionary mechanism of cancer.

Cancer progression represents an evolutionary process where overall genome level changes reflect system instability and serve as a driving force for evolving new systems. To illustrate this principle it must be demonstrated that karyotypic heterogeneity (population diversity) directly contributes to tumorigenicity. Five well characterized in vitro tumor progression models representing various types of cancers were selected for such an analysis. The tumorigenicity of each model has been linked to different molecular pathways, and there is no common molecular mechanism shared among them. According to our hypothesis that genome level heterogeneity is a key to cancer evolution, we expect to reveal that the common link of tumorigenicity between these diverse models is elevated genome diversity. Spectral karyotyping (SKY) was used to compare the degree of karyotypic heterogeneity displayed in various sublines of these five models. The cell population diversity was determined by scoring type and frequencies of clonal and non-clonal chromosome aberrations (CCAs and NCCAs). The tumorigenicity of these models has been separately analyzed. As expected, the highest level of NCCAs was detected coupled with the strongest tumorigenicity among all models analyzed. The karyotypic heterogeneity of both benign hyperplastic lesions and premalignant dysplastic tissues were further analyzed to support this conclusion. This common link between elevated NCCAs and increased tumorigenicity suggests an evolutionary causative relationship between system instability, population diversity, and cancer evolution. This study reconciles the difference between evolutionary and molecular mechanisms of cancer and suggests that NCCAs can serve as a biomarker to monitor the probability of cancer progression.

Increased invasion through basement membrane by CXCL7-transfected breast cells.

BACKGROUND: CXC chemokines may modify breast cancer cells and surrounding extracellular matrix to facilitate metastasis. CXCL7 is heparin binding, has heparanase activity, and is a ligand to CXCR2, a G-protein-linked receptor. METHODS: Isogenic cell lines, malignant MCF10CA1a.cl1 cells, and premalignant MCF10AT cells were used. CXCR2 and CXCL7 expression levels were quantified by reverse transcriptionase-polymerase chain reaction and Western blot. MCF10AT cells were stably transfected with CXCL7, and matrigel invasion assays were performed. Antibody to CXCL7 was used to inhibit invasion. CXCL7 secretion by transfectants and heparanase activity were quantified by enzyme-linked immunosorbent assay. RESULTS: CXCL7 and CXCR2 expression were significantly higher in malignant MCF10CA1a.cl1 cells than in premalignant MCF10AT cells. Secreted CXCL7, secreted heparanase activity, and invasiveness were all increased in CXCL7-transfected MCF10AT cells. CXCL7 antibody inhibited invasion of CXCL7-transfected MCF10AT cells. CONCLUSIONS: Malignant MCF10CA1a.cl1 cells express more CXCL7 and CXCR2 than premalignant MCF10AT cells. CXCL7-transfected MCF10AT cells are as invasive as malignant breast cancer cells.

Comedo-ductal carcinoma in situ: A paradoxical role for programmed cell death.

Comedo-DCIS is a histologic subtype of preinvasive breast neoplasia that is characterized by prominent apoptotic cell death and has greater malignant potential than other DCIS subtypes. We investigated the mechanisms of apoptosis in comedo-DCIS and its role in conversion of comedo-DCIS to invasive cancer. Clinical comedo-DCIS excisions and the MCF10DCIS.com human breast cancer model which produces lesions resembling comedo-DCIS were analyzed. Apoptotic luminal and myoepithelial cells were identified by TUNEL and reactivity to cleaved PARP antibody and cell death assessed by Western blotting, Mitocapture and immunohistochemical assays. MCF10DCIS.com cells undergo spontaneous apoptosis in vitro, both in monolayers and multicellular spheroids; it is associated with increased mitochondrial membrane permeability, increase in Bax/Bcl-2 ratio and occurs via caspase-9-dependent p53-independent pathway. This suggests that apoptosis is stromal-independent and that the cells are programmed to undergo apoptosis. Immunostaining with cleaved PARP antibody showed that myoepithelial apoptosis occurs before lesions progress to comedo-DCIS in both clinical comedo-DCIS and in vivo MCF10DCIS.com lesions. Intense staining for MMP-2, MMP-3, MMP-9 and MMP-11 was observed in the stroma and epithelia of solid DCIS lesions prior to conversion to comedo-DCIS in clinical and MCF10DCIS.com lesions. Gelatin zymography showed higher MMP-2 levels in lysates and conditioned media of MCF10DCIS. com cells undergoing apoptosis. These data suggest that signals arising from the outside (microenvironmental) and inside (internal genetic alterations) of the duct act in concert to trigger apoptosis of myoepithelial and luminal epithelial cells. Our findings implicate spontaneous apoptosis in both the etiology and progression of comedo-DCIS. It is possible that spontaneous apoptosis facilitates elimination of cells thus permitting expansion and malignant transformation of cancer cells that are resistant to spontaneous apoptosis.

Membrane glycoproteins associated with breast tumor cell progression identified by a lectin affinity approach.

The membrane glycoprotein component of the cellular proteome represents a promising source for potential disease biomarkers and therapeutic targets. Here we describe the development of a method that facilitates the analysis of membrane glycoproteins and apply it to the differential analysis of breast tumor cells with distinct malignant phenotypes. The approach combines two membrane extraction procedures, and enrichment using ConA and WGA lectin affinity columns, prior to digestion and analysis by LC-MS/MS. The glycoproteins are identified and quantified by spectral counting. Although the distribution of glycoprotein expression as a function of MW and p I was very similar between the two related cell lines tested, the approach enabled the identification of several distinct membrane glycoproteins with an expression index correlated with either a precancerous (MCF10AT1), or a malignant, metastatic cellular phenotype (MCF10CA1a). Among the proteins associated with the malignant phenotype, Gamma-glutamyl hydrolase, CD44, Galectin-3-binding protein, and Syndecan-1 protein have been reported as potential biomarkers of breast cancer.

A novel phosphoprotein analysis scheme for assessing changes in premalignant and malignant breast cell lines using 2D liquid separations, protein microarrays and tandem mass spectrometry.

An analysis of phosphorylation changes that occur during cancer progression would provide insights into the molecular pathways responsible for a malignant phenotype. In this study we employed a novel coupling of 2D-liquid separations and protein microarray technology to reveal changes in phosphoprotein status between premalignant (AT1) and malignant (CA1a) cell lines derived from the human MCF10A breast cell lines. Intact proteins were first separated according to their isoelectric point and hydrophobicities, then arrayed on SuperAmine glass slides. Phosphoproteins were detected using the universal, inorganic phospho-sensor dye, ProQ Diamond. Using this dye, out of 140 spots that were positive for phosphorylation, a total of 85 differentially expressed spots were detected over a pH range of 7.2 to 4.0. Proteins were identified and their peptides sequenced by mass spectrometry. The strategy enabled the identification of 75 differentially expressed phosphoproteins, from which 51 phosphorylation sites in 27 unique proteins were confirmed. Interestingly, the majority of differentially expressed phosphorylated proteins observed were nuclear proteins. Three regulators of apoptosis, Bad, Bax and Acinus, were also differentially phosphorylated in the two cell lines. Further development of this strategy will facilitate an understanding of the mechanisms involved in malignancy progression and other disease-related phenotypes.

Expression patterns of lymphangiogenic and angiogenic factors in a model of breast ductal carcinoma in situ.

BACKGROUND: Foci of invasion are found in greater than 20% of excised specimens of breast ductal carcinoma in situ (DCIS). Since lymphangiogenesis markers are associated with the potential for increased lymph node metastasis, the purpose of the current study was to determine expression of lymphangiogenesis molecular markers in a model of aggressive DCIS. METHODS: From the MCF10A xenograft model, comedo type MCF10DCIS.com cells, premalignant MCF10AT, and invasive MCF10CA1a.cl1 cells were tested. Invasion was tested by Matrigel invasion assays (Becton-Dickinson, Bedford, MA). Gene expression was determined by reverse transcriptase-polymerase chain reaction and protein expression by immunoblot, normalized to beta-actin. RESULTS: MCF10DCIS.com cells were 4-fold more invasive than MCF10AT cells (P < .01), and expressed several-fold more mRNA and protein than MCF10AT and MCF10CA1a.cl1 cells for vascular endothelial growth factor C, vascular endothelial growth factor D, and lymphatic vessel endothelial hyaluronan receptor 1 (P < .01). CONCLUSIONS: A subset of comedo-type DCIS cells are invasive, and expression of lymphangiogenesis markers is greater at the mRNA and protein levels than by invasive cancer cells (P < .01). These additional molecular markers may characterize aggressive DCIS more precisely.

Differential expression of acidic proteins with progression in the MCF10 model of human breast disease.

A proteomic characterization of one premalignant (MCF10AT1) and two malignant (MCF10CA1a and MCF10 CA1d) human breast cancer cell lines has been performed using a combination of two-dimensional liquid separations and mass spectrometry. Chromatofocusing (CF) and NPS-RP-HPLC are combined with ESI-TOF-MS to resolve and detect intact proteins. Simultaneously, fractions are collected and digested for protein identification using MALDI-MS peptide mass fingerprinting. Following protein identification a small database was compiled for use in comparison between IDs and measured masses taking into account variables such as pI, hydrophobicity and potential modifications. Out of 239 mass bands detected between pH 4.6 and 6.0, 133 have been definitively associated with identified proteins and 67 show consistent up/down regulation in two malignant breast cancer cell lines relative to the precursor premalignant cell line. Of these, 8 are also altered in the premalignant MCF10AT1 cell line by treatment with estradiol. Differentially expressed proteins indicate significant changes to the cytoskeleton, cellular metabolism, and adaptation to environmental stressors in malignant cell lines.

Dynamic stromal-epithelial interactions during progression of MCF10DCIS.com xenografts.

MCF10DCIS.com cells form comedo type ductal carcinoma in situ in immune-deficient mice before forming invasive ductal carcinoma. As the lesions mature, both stromal and epithelial cells undergo phenotypic changes detected by immunohistochemistry. Myofibroblasts are present before the formation of carcinoma in situ and after development of invasive carcinoma. MCF10DCIS. com lesions develop a myoepithelial layer prior to exhibiting a basement membrane surrounding the ductal mass. TGFbeta1 is initially expressed by the epithelial cells but is expressed by stroma in invasive carcinoma. Stromal derived factor-1 is detected in epithelial cells in early carcinoma in situ but is produced in stromal cells in invasive carcinoma. The receptor CXCR4 is expressed by epithelial cells in the xenografts at all times, as is the hepatocyte growth factor receptor c-met. MCF10DCIS.com xenografts illustrate the dynamic interplay of epithelium and stroma in the development of carcinoma in situ and subsequent invasive carcinoma. Although the phenotype of the epithelial cells may be dependent upon the stroma, the malignant epithelium induces the development of the stroma necessary for progression to the invasive stage. (c) 2007 Wiley-Liss, Inc.

Comprehensive analysis of proteins of pH fractionated samples using monolithic LC/MS/MS, intact MW measurement and MALDI-QIT-TOF MS.

A comprehensive platform that integrates information from the protein and peptide levels by combining various MS techniques has been employed for the analysis of proteins in fully malignant human breast cancer cells. The cell lysates were subjected to chromatofocusing fractionation, followed by tryptic digestion of pH fractions for on-line monolithic RP-HPLC interfaced with linear ion trap MS analysis for rapid protein identification. This unique approach of direct analysis of pH fractions resulted in the identification of large numbers of proteins from several selected pH fractions, in which approximately 1.5 microg of each of the pH fraction digests was consumed for an analysis time of ca 50 min. In order to combine valuable information retained at the protein level with the protein identifications obtained from the peptide level information, the same pH fraction was analyzed using nonporous (NPS)-RP-HPLC/ESI-TOF MS to obtain intact protein MW measurements. In order to further validate the protein identification procedures from the fraction digest analysis, NPS-RP-HPLC separation was performed for off-line protein collection to closely examine each protein using MALDI-TOF MS and MALDI-quadrupole ion trap (QIT)-TOF MS, and excellent agreement of protein identifications was consistently observed. It was also observed that the comparison to intact MW and other MS information was particularly useful for analyzing proteins whose identifications were suggested by one sequenced peptide from fraction digest analysis.