Expression of Beta Protein 1 (BP1), a homeotic transcription factor, increases during breast cancer progression and may be associated with tumor aggressiveness. In our present work, we investigate ...the influence of BP1 on breast tumor formation and size in vitro and in vivo. Cells overexpressing BP1 showed higher viability when grown in the absence of serum (p < 0.05), greater invasive potential (p < 0.05) and formed larger colonies (p < 0.004) compared with the controls. To determine the influence of BP1 overexpression on tumor characteristics, MCF-7 cells transfected with either empty vector (V1) or overexpressor plasmids (O2 and O4) were injected into the fat pads of athymic nude mice. Tumors grew larger in mice receiving O2 or O4 cells than in mice receiving V1 cells. Moreover, BP1 mRNA expression levels were positively correlated with tumor size in patients (p = 0.01). Interestingly, 20% of mice injected with O2 or O4 cells developed tumors in the absence of estrogen, while no mice receiving V1 cells developed tumors. Several mechanisms of estrogen independent tumor formation related to BP1 were established. These data are consistent with the fact that expression of breast cancer anti-estrogen resistance 1 (BCAR1) was increased in O2 compared to V1 cells (p < 0.01). Importantly, O2 cells exhibited increased proliferation when treated with tamoxifen, while V1 cells showed growth inhibition. Overall, BP1 overexpresssion in MCF-7 breast cancer cells leads to increased cell growth, estrogen-independent tumor formation, and increased proliferation. These findings suggest that BP1 may be an important biomarker and therapeutic target in ER positive breast cancer.
Tamoxifen is the first line of therapy for most human breast cancers. It not only works through the estrogen receptor but also can directly affect the binding of prolactin to its receptor. To define ...this latter mechanism, the nature of the prolactin receptor needs to be clearly defined. Monoclonal antibody (MAb) B6.2, and IgG1 raised against a membrane-enriched fraction from metastatic human breast cancer cells, was as effective as polyclonal anti-prolactin receptor antibody in inhibiting the binding of prolactin to membranes from human tissue and to T47D human breast cancer cells. Control MAbs, MOPC-2I and the anti-NCA B1.1 MAb, had no effect on binding. Epidermal growth-factor receptors on these same cells were unaffected by B6.2. Prolactin-induced growth of the T47D cells was blocked by addition of B6.2 to the media while the control antibodies were without effect. Specific binding of B6.2 to the cells was completely inhibited by prolactin. Binding of both prolactin and B6.2 was inhibited by growing the T47D cells in the presence of tunicamycin A1 under conditions where protein synthesis was not affected but glycosylation of proteins was. An affinity column of B6.2 was used to purify its antigen from T47D cells. The primary purification product, a M(r) 90,000 protein, specifically bound the lactogenic hormones human prolactin, human growth hormone and ovine prolactin but not the somatogenic hormone, bovine growth hormone and was precipitated by the polyclonal anti-prolactin receptor antibody but not by control MAbs. When tryptic and V8 digests of the B6.2 antigen and purified prolactin receptors were compared, identical electrophoretic profiles were obtained. Mouse 3T3 cells, when stably transfected with the gene for the long form of the human prolactin receptor, reacted with B6.2 and polyclonal anti-prolactin receptor antibody. Parental 3T3 cells, devoid of prolactin receptors, were negative for all antibodies tested. Thus, MAb B6.2 provides a useful tool for further studies on purification and characterization of these receptors from human tissues and may provide new insights into treatment for breast cancer.
A possible autocrine function of prolactin (Prl) in human breast cancer was explored by the addition of a panel of anti-human Prl mAbs to T47Dco and MCF7 human breast adenocarcinoma cells. mAb 631 ...and mAb 390 inhibited cell growth by 86 and 68%, respectively, in the estrogen receptor-negative T47Dco cells and by 20 and 71%, respectively, in the estrogen receptor-positive MCF7 cells. Conditioned medium prepared from T47Dco cells was assessed for the presence of Prl-like molecules by its ability to stimulate growth of Prl-responsive Nb2 rat lymphoma cells. Growth of Nb2 cells under the influence of human Prl or conditioned medium was abolished when either solution was pretreated with mAb 390, followed by Immunobead precipitation (Bio-Rad, Melville, NY). T47Dco cells secrete 0.7 microgram lactogen/ml over a 24-48-h period. With the use of reverse transcription-PCR, an expected 612-bp band was detected by ethidium bromide staining, and its similarity to pituitary Prl was confirmed by Southern blot analysis with the use of human Prl cDNA as a probe. A single M(r) 22,000 band, the dominant size of monomeric pituitary Prl, was found in immunoprecipitates of both cell extracts and conditioned medium from T47Dco cells labeled metabolically with 35Scysteine. These data suggest that human breast cancer cells synthesize and secrete biologically active Prl.
Role of Human Cripto-1 in Tumor Angiogenesis Bianco, Caterina; Strizzi, Luigi; Ebert, Andreas ...
JNCI : Journal of the National Cancer Institute,
01/2005, Letnik:
97, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Background: Human cripto-1 (CR-1) promotes cell transformation and increases migration and invasion of various mouse and human epithelial cell lines. We investigated whether CR-1 also stimulates ...angiogenesis. Methods: We used human umbilical vein endothelial cells (HUVECs) to measure in vitro migration with fibronectin-coated Boyden chambers, invasion with Matrigel-coated Boyden chambers, proliferation with a tetrazolium salt, and differentiation with an in vitro Matrigel assay. We investigated new blood vessel formation in vivo by use of Matrigel-filled silicone cylinders implanted under the skin of nude mice and by use of a breast cancer xenograft model with CR-1-transfected or control Neo-transfected MCF-7 human breast cancer cells. We also used a blocking anti-CR-1 monoclonal antibody to investigate the role of CR-1 in angiogenesis in vivo and in vitro. All statistical tests were two-sided. Results: CR-1 stimulated HUVEC proliferation, migration, and invasion and induced HUVEC differentiation into vascular-like structures on Matrigel. In vivo, recombinant CR-1 protein induced microvessel formation in Matrigel-filled silicone cylinders, and microvessel formation was statistically significantly inhibited with a blocking anti-CR-1 monoclonal antibody (CR-1 and antibody = 127% of microvessel formation compared with that in untreated control cylinders and CR-1 alone = 259%; difference = 132%, 95% confidence interval CI = 123% to 140%; P<.001). Tumors formed by CR-1-transfected MCF-7 cells in the cleared mammary fat pad of nude mice had higher microvessel density than tumors formed by control Neo-transfected MCF-7 cells (CR-1-transfected cells = 4.66 vessels per field and Neo-transfected cells = 2.33 vessels per field; difference = 2.33 vessels per field, 95% CI = 1.2 to 2.8; P = .004). Conclusion: CR-1 appears to have an important role in the multistep process of angiogenesis.
Introduction The invasive, mesenchymal phenotype of CD44.sup.pos.sup.CD24.sup.neg .sup.breast cancer cells has made them a promising target for eliminating the metastatic capacity of primary tumors. ...It has been previously demonstrated that CD44.sup.neg/low.sup.CD24.sup.pos .sup.breast cancer cells lack the ability to give rise to their invasive CD44.sup.pos.sup.CD24.sup.neg .sup.counterpart. Here we demonstrate that noninvasive, epithelial-like CD44.sup.pos.sup.CD24.sup.pos .sup.cells readily give rise to invasive, mesenchymal CD44.sup.pos.sup.CD24.sup.neg .sup.progeny in vivo and in vitro. This interconversion was found to be dependent upon Activin/Nodal signaling. Methods Breast cancer cell lines were sorted into CD44.sup.pos.sup.CD24.sup.pos .sup.and CD44.sup.pos.sup.CD24.sup.neg .sup.populations to evaluate their progeny for the expression of CD44, CD24, and markers of a mesenchymal phenotype. The populations, separated by fluorescence activated cell sorting (FACS) were injected into immunocompromised mice to evaluate their tumorigenicity and invasiveness of the resulting xenografts. Results CD24 expression was dynamically regulated in vitro in all evaluated breast cancer cell lines. Furthermore, a single noninvasive, epithelial-like CD44.sup.pos.sup.CD24.sup.pos .sup.cell had the ability to give rise to invasive, mesenchymal CD44.sup.pos.sup.CD24.sup.neg .sup.progeny. Importantly, this interconversion occurred in vivo as CD44.sup.pos.sup.CD24.sup.pos .sup.cells gave rise to xenografts with locally invasive borders as seen in xenografts initiated with CD44.sup.pos.sup.CD24.sup.neg .sup.cells. Lastly, the ability of CD44.sup.pos.sup.CD24.sup.pos .sup.cells to give rise to mesenchymal progeny, and vice versa, was blocked upon ablation of Activin/Nodal signaling. Conclusions Our data demonstrate that the invasive, mesenchymal CD44.sup.pos.sup.CD24.sup.neg .sup.phenotype is under dynamic control in breast cancer cell lines both in vitro and in vivo. Furthermore, our observations suggest that therapies targeting CD44.sup.pos.sup.CD24.sup.neg .sup.tumor cells may have limited success in preventing primary tumor metastasis unless Activin/Nodal signaling is arrested.
The invasive, mesenchymal phenotype of CD44posCD24neg breast cancer cells has made them a promising target for eliminating the metastatic capacity of primary tumors. It has been previously ...demonstrated that CD44neg/lowCD24pos breast cancer cells lack the ability to give rise to their invasive CD44posCD24neg counterpart. Here we demonstrate that noninvasive, epithelial-like CD44posCD24pos cells readily give rise to invasive, mesenchymal CD44posCD24neg progeny in vivo and in vitro. This interconversion was found to be dependent upon Activin/Nodal signaling.
Breast cancer cell lines were sorted into CD44posCD24pos and CD44posCD24neg populations to evaluate their progeny for the expression of CD44, CD24, and markers of a mesenchymal phenotype. The populations, separated by fluorescence activated cell sorting (FACS) were injected into immunocompromised mice to evaluate their tumorigenicity and invasiveness of the resulting xenografts.
CD24 expression was dynamically regulated in vitro in all evaluated breast cancer cell lines. Furthermore, a single noninvasive, epithelial-like CD44posCD24pos cell had the ability to give rise to invasive, mesenchymal CD44posCD24neg progeny. Importantly, this interconversion occurred in vivo as CD44posCD24pos cells gave rise to xenografts with locally invasive borders as seen in xenografts initiated with CD44posCD24neg cells. Lastly, the ability of CD44posCD24pos cells to give rise to mesenchymal progeny, and vice versa, was blocked upon ablation of Activin/Nodal signaling.
Our data demonstrate that the invasive, mesenchymal CD44posCD24neg phenotype is under dynamic control in breast cancer cell lines both in vitro and in vivo. Furthermore, our observations suggest that therapies targeting CD44posCD24neg tumor cells may have limited success in preventing primary tumor metastasis unless Activin/Nodal signaling is arrested.
Msx-1 and Msx-2 in mammary gland development SATOH, Kennichi; GINSBURG, Erika; VONDERHAAR, Barbara K
Journal of mammary gland biology and neoplasia,
2004, Letnik:
9, Številka:
2
Journal Article
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