Angiotensin II type 1 receptor antagonists inhibit cell proliferation and angiogenesis in breast cancer

Angiotensin II type 1 receptor (AT1R) promotes tumor invasion, migration, metastasis and angiogenesis. We explored the potential antitumor effects of AT1R antagonists in breast cancer. We found that angiotensin II promoted cell proliferation and upregulated the expression of vascular endothelial growth factor A (VEGF-A) in MCF-7 cells. Losartan downregulated the expression of VEGF-A in MCF-7 cells treated with angiotensin II. Candesartan downregulated the expression of VEGF-A in mice bearing MCF-7 xenografts and inhibited tumor growth and angiogenesis. AT1R and VEGF-A expression correlated with increased microvascular density in 102 breast cancer patients. Our data suggest that AT1R antagonists might be useful to suppress breast cancer by inhibiting the angiotensin II.     

p53负向调控肺癌A549细胞Wnt通路活性并抑制其增殖和侵袭

目的:探讨野生型p53对Wnt通路的调节以及对肺癌细胞生物学行为的影响。方法:分别利用野生型p53质粒及siRNA,分别转染和干扰A549细胞中的野生型p53,而后用Western blot检测A549细胞中β-catenin和cyclin D1的表达,用荧光素酶报告基因法检测Wnt通路活性,用MTT和Transwell实验检测A549细胞的增殖和侵袭能力。结果:转染野生型p53后能够明显下调A549细胞中β-catenin和cyclin D1表达(P<0.01),抑制肺癌细胞的增殖和侵袭(P<0.05),而干扰p53可以明显地上调β-catenin和cyclin D1表达(P<0.01),增强肺癌细胞的增殖力和侵袭力(P<0.05)。结论:野生型p53负向调控A549细胞中的Wnt信号转导通路,抑制其增殖和侵袭能力。     

乳腺癌细胞耐药过程中p38MAPK活性与细胞凋亡的关系

目的研究乳腺癌细胞耐药过程中p38MAPK活性与细胞凋亡的关系,探讨p38MAPK信号转导途径在其中的作用。方法 以p38MAPK特异性抑制剂SB203580处理乳腺癌耐药细胞MCF-7／ADM,采用流式细胞技术分析对细胞凋亡的影响;MTT检测MCF-7／ADM细胞对阿霉素的半数药物抑制浓度（IC50）;Western blot检测SB203580处理MCF-7／ADM和MCF-7两株细胞后p38MAPK蛋白表达水平;RT—PCR检测细胞内MDR-1 mRNA水平。结果SB203580（10μmol／L）干预24h后MCF-7／ADM细胞的凋亡率为（26．73±4．90）％,与未干预组和对照组凋亡率相比差异有显著统计学意义（F=143．80,P〈0．001）;MCF-7／ADM细胞对阿霉素的敏感性明显提高（F=148927．10,P〈0．001）,相对逆转率达68．45％;与对照组和未干预组相比,干预组的MDR1 mRNA（F=9139．24,P〈0．001）及p38MAPK（F=685．42,P〈0．001）蛋白表达水平明显降低。结论p38MAPK信号转导途径与乳腺癌耐药密切相关,其可能机制为p38MAPK保护人乳腺癌耐药细胞（MCF-7／ADM）逃避凋亡,阻断该通路可增强乳腺癌耐药细胞发生凋亡。     

Role of Src in breast cancer cell migration and invasion in a breast cell/bone-derived cell microenvironment

The preferential metastasis of breast cancer cells to bone comprises a complex set of events including homing and preferential growth, which may require unique factors produced by bone or other cells in the immediate microenvironment. In this study, an in vitro co-culture system composed of bone mesenchymal stem cells and breast cancer cell lines is used to examine the role of Src kinase on breast cancer cell migration and invasion in the presence of bone-derived cells. This research shows that Src kinase activity in breast cancer cell lines with either high or low levels of endogenous Src activity is increased by bone-derived cell-conditioned medium but not HS68 fibroblast-conditioned medium. Breast cancer cells exhibit enhanced migration in co-culture with bone-derived cells but not HS68 fibroblasts or no co-cultured cells. Inhibition of Src kinase activity using the inhibitors PP2 or saracatinib or using siRNA abrogates the preferential migration of the breast cancer cell lines in response to bone-derived cells. Inhibition of Src activity with saracatinib does not have any significant effect on breast cancer cell invasion in the presence of bone-derived cells. Factors are identified that are produced preferentially by bone-derived cells over HS68 cells that may impact breast cancer cell behavior. This research implicates Src kinase as an important effector of bone-derived cell signals on breast cancer cell migration.     

p38 MAPK inhibits breast cancer metastasis through regulation of stromal expansion

p38 MAPK signaling controls cell growth, proliferation and the cell cycle under stress conditions. However, the function of p38 activation in tumor metastasis is still not well understood. We report that p38 activation in breast cancer cells inhibits tumor metastasis but does not substantially modulate primary tumor growth. Stable p38 knockdown in breast cancer cells suppressed NF‐κB p65 activation, inhibiting miR‐365 expression and resulting in increased IL‐6 secretion. The inhibitory effect of p38 signaling on metastasis was mediated by suppression of mesenchymal stem cell (MSC) migration to the primary tumor and sites of metastasis, where MSCs can differentiate into cancer‐associated fibroblasts to promote tumor metastasis. The migration of MSCs to these sites relies on CXCR4‐SDF1 signaling in the tumor microenvironment. Analysis of human primary and metastatic breast cancer tumors showed that p38 activation was inversely associated with IL‐6 and vimentin expression. This study suggests that combination analysis of p38 MAPK and IL‐6 signaling in patients with breast cancer may improve prognosis and treatment of metastatic breast cancer.     

The type III TGF-beta receptor signals through both Smad3 and the p38 MAP kinase pathways to contribute to inhibition of cell proliferation

Transforming growth factor beta (TGFbeta) has an important role as a negative regulator of cellular proliferation. The type III transforming growth factor beta receptor (TbetaRIII) has an emerging role as both a TGFbeta superfamily co-receptor and in mediating signaling through its cytoplasmic domain. In L6 myoblasts, TbetaRIII expression enhanced TGFbeta1-mediated growth inhibition, with this effect mediated, in part, by the TbetaRIII cytoplasmic domain. The effects of TbetaRIII were not due to altered ligand presentation or to differences in Smad2 phosphorylation. Instead, TbetaRIII specifically increased Smad3 phosphorylation, both basal and TGFbeta-stimulated Smad3 nuclear localization and Smad3-dependent activation of reporter genes independent of its cytoplasmic domain. Conversely, SB431542, a type I transforming growth factor beta receptor (TbetaRI) inhibitor, as well as dominant-negative Smad3 specifically and significantly abrogated the effects of TbetaRIII on TGFbeta1-mediated inhibition of proliferation. TbetaRIII also specifically increased p38 phosphorylation, and SB203580, a p38 kinase inhibitor, specifically and significantly abrogated the effects of TbetaRIII/TGFbeta1-mediated inhibition of proliferation in L6 myoblasts and in primary human epithelial cells. Importantly, treatment with the TbetaRI and p38 inhibitors together had additive effects on abrogating TbetaRIII/TGFbeta1-mediated inhibition of proliferation. In a reciprocal manner, short hairpin RNA-mediated knockdown of endogenous TbetaRIII in various human epithelial cells attenuated TGFbeta1-mediated inhibition of proliferation. Taken together, these data demonstrate that TbetaRIII contributes to and enhances TGFbeta-mediated growth inhibition through both TbetaRI/Smad3-dependent and p38 mitogen-activated protein kinase pathways.     

乳腺癌细胞药耐中P38MAPK活性与凋亡关系的实验研究

Objective  

The aim of this study was to investigate the relationship between p38MAPK activity and apoptosis during the drug resistance of breast carcinoma cell lines.     

Numblike regulates proliferation, apoptosis, and invasion of lung cancer cell

Numblike (Numbl), a conserved homolog of Drosophila Numb, has been proved to be implicated in early development of the nervous system. A recent study also showed that Numbl played an important role in tumorigenesis and invasion by suppressing NF-κB activation. However, the biological role of Numbl remains unknown in lung cancer up to now. To address the expression of Numbl in the lung cancer cell, four lung cancer cell lines (metastatic cell lines NCI-H292, 95-D, and non-metastatic cell lines A549, HCC827) and non-cancerous human bronchial epithelial cells were used to detect the protein expression of Numbl by western blotting. The results in this study indicated that the expression of Numbl was downregulated in human lung cancer cell lines, especially in metastatic cell lines. To investigate the role of Numbl in lung cancer cell proliferation, apoptosis, and invasion, we generated human lung cancer 95-D cell lines in which Numbl was either overexpressed or depleted. Subsequently, the effects of Numbl on the cell viability, cycle, apoptosis, and invasion properties in 95-D cells were determined with MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay, flow cytometry analysis, and Transwell invasion assays. The results indicated that Numbl could decrease cell viability, suppress cell proliferation and invasion, and promote cell apoptosis. In addition, we investigated the effects of Numbl on the expression of the following proteins: TRAF6 (tumor necrosis factor receptor-associated factor 6), p-p65 (phosphor-NF-κB), cyclin D1, caspase-3, and matrix metalloproteinase 9 (MMP9). Results showed that Numbl could decrease the expression of TRAF6, p-p65, cyclin D1, and MMP9 and increase the expression of caspase-3. All these results suggested that Numbl might be involved in the inhibition of growth, proliferation, and invasion of 95-D cells, as well as the potentiation of apoptosis of 95-D cells by abrogating TRAF6-induced activation of NF-κB.     

miRNA423-5p regulates cell proliferation and invasion by targeting trefoil factor 1 in gastric cancer cells

TFF1 is a small, secreted protein in the TFF family that has a pivotal role as a motogenic factor in epithelial restitution and cell motility, and as a tumor suppressor gene in the stomach. In this study, we identified TFF1 as a novel target gene of miRNA-423-5p. miRNA-423-5p negatively regulated the expression of TFF1 by binding to its 3′UTR and participated in proliferation/invasion-related processes via a TFF1-dependent manner in gastric cancer cells. Our findings suggested that miR-423-5p may be a novel target for the future development of specific therapeutic interventions for gastric cancer.     

Androgen receptor non-nuclear regulation of prostate cancer cell invasion mediated by Src and matriptase

Castration-resistant prostate cancers still depend on nuclear androgen receptor (AR) function despite their lack of dependence on exogenous androgen. Second generation anti-androgen therapies are more efficient at blocking nuclear AR; however resistant tumors still develop. Recent studies indicate Src is highly active in these resistant tumors. By manipulating AR activity in several different prostate cancer cell lines through RNAi, drug treatment, and the use of a nuclear-deficient AR mutant, we demonstrate that androgen acting on cytoplasmic AR rapidly stimulates Src tyrosine kinase via a non-genomic mechanism. Cytoplasmic AR, acting through Src enhances laminin integrin-dependent invasion. Active Matriptase, which cleaves laminin, is elevated within minutes after androgen stimulation, and is subsequently shed into the medium. Matriptase activation and shedding induced by cytoplasmic AR is dependent on Src. Concomitantly, CDCP1/gp140, a Matriptase and Src substrate that controls integrin-based migration, is activated. However, only inhibition of Matriptase, but not CDCP1, suppresses the AR/Src-dependent increase in invasion. Matriptase, present in conditioned medium from AR-stimulated cells, is sufficient to enhance invasion in the absence of androgen. Thus, invasion is stimulated by a rapid but sustained increase in Src activity, mediated non-genomically by cytoplasmic AR, leading to rapid activation and shedding of the laminin protease Matriptase.     

HOXA10 regulates p53 expression and matrigel invasion in human breast cancer cells

HOX genes regulate cell differentiation during embryonic development. Here we demonstrate HOXA10 expression in both benign and malignant adult human breast tissue and in MCF-7, but not BT20 breast cancer cells. We have previously shown that HOXA10 mediates uterine differentiation in response to estrogens. The mechanism of action of estradiol and other estrogen receptor modulators on breast cancer cell growth is still poorly understood. MCF-7 cells, which are ER (+) and express HOXA10, were used to assay the effect of estradiol and tamoxifen on HOXA10 expression. Semi-quantitative RT-PCR and northern analysis revealed that treatment with either estradiol or tamoxifen increased HOXA10 mRNA expression. BT20 cells, which are ER (-) and do not endogenously express HOXA10, were used to assay the effect of increased HOXA10 expression on p53 expression and on the invasive phenotype. Constitutively expressing HOXA10 in BT20 cells increased p53 protein expression. Increased HOXA10 also reduced invasiveness through matrigel. The mechanism by which estrogen and other estrogen receptor modulators influence both normal breast development as well as breast cancer may involve the regulation of developmental control genes such as HOXA10; HOXA10 in turn regulates expression of key downstream genes such as p53 and regulates tumor cell functional phenotype.     

TRPM7 mediates breast cancer cell migration and invasion through the MAPK pathway

Metastasis is an inherent feature of breast cancer and transient receptor potential (TRP) channels were found to be potentially implicated in this process. Particularly, TRPM7 may regulate cell motility. We therefore examined the expression of TRPM7 mRNA in the Oncomine database and found that TRPM7 is correlated to metastasis and invasive breast cancer. Silencing TRPM7 with RNA interference resulted in a significant decrease in migration and invasion capability of MDA-MB-435 breast cancer cells, and phosphorylation levels of Src and MAPK but not AKT. Our results suggest that TRPM7 regulates migration and invasion of metastatic breast cancer cells via MAPK pathway.     

p38gamma mitogen-activated protein kinase integrates signaling crosstalk between Ras and estrogen receptor to increase breast cancer invasion

Ras is believed to stimulate invasion and growth by different effector pathways, and yet, the existence of such effectors under physiologic conditions has not been shown. Estrogen receptor (ER), on the other hand, is both anti-invasive and proliferative in human breast cancer, with mechanisms for these paradoxical actions remaining largely unknown. Our previous work showed an essential role of p38gamma mitogen-activated protein kinase in Ras transformation in rat intestinal epithelial cells, and here, we show that p38gamma integrates invasive antagonism between Ras and ER to increase human breast cancer invasion without affecting their proliferative activity. Ras positively regulates p38gamma expression, and p38gamma in turn mediates Ras nonmitogenic signaling to increase invasion. Expression of the Ras/p38gamma axis, however, is trans-suppressed by ER that inhibits invasion and stimulates growth also by distinct mechanisms. Analysis of ER and its cytoplasmic localized mutant reveals that ER additionally binds to p38gamma protein, leading to its specific down-regulation in the nuclear compartment. A p38gamma-antagonistic activity of ER was further shown in a panel of breast cancer cell lines and was shown independent of estrogens by both ER depletion and ER expression. These results revealed that both Ras and ER use distinct pathways to regulate breast cancer growth and invasion, and that p38gamma specifically integrates their antagonistic activity to stimulate cell invasion. Selective targeting of p38gamma-dependent invasion pathways may be a novel strategy to control breast cancer progression.     

Targeted intraoperative radiotherapy impairs the stimulation of breast cancer cell proliferation and invasion caused by surgical wounding.

PURPOSE: After apparently successful excision of breast cancer, risk of local recurrence remains high mainly in the area surrounding the original tumor, indicating that wound healing processes may be implicated. The proportional reduction of this risk by radiotherapy does not depend on the extent of surgery, suggesting that radiotherapy, in addition to killing tumor cells, may influence the tumor microenvironment. EXPERIMENTAL DESIGN: We studied how normal and mammary carcinoma cell growth and motility are affected by surgical wound fluids (WF), collected over 24 h following breast-conserving surgery in 45 patients, 20 of whom had received additional TARGeted Intraoperative radioTherapy (TARGIT), immediately after the surgical excision. The proteomic profile of the WF and their effects on the activation of intracellular signal transduction pathways of breast cancer cells were also analyzed. RESULTS: WF stimulated proliferation, migration, and invasion of breast cancer cell lines. The stimulatory effect was almost completely abrogated when fluids from TARGIT-treated patients were used. These fluids displayed altered expression of several cytokines and failed to properly stimulate the activation of some intracellular signal transduction pathways, when compared with fluids harvested from untreated patients. CONCLUSIONS: Delivery of TARGIT to the tumor bed alters the molecular composition and biological activity of surgical WF. This novel antitumoral effect could, at least partially, explain the very low recurrence rates found in a large pilot study using TARGIT. It also opens a novel avenue for identifying new molecular targets and testing novel therapeutic agents.     

Tyr23 phosphorylation of Anxa2 enhances STAT3 activation and promotes proliferation and invasion of breast cancer cells

Purpose

Overexpression of Annexin A2 (Anxa2) is positively correlated with breast cancer progression, drug resistance, and poor prognosis of patients with breast cancer. Tyr23 Phosphorylation by Src-family tyrosine kinase is an important post-translational modification of Anxa2. This modification regulates the subcellular localization and functions of Anxa2 and has significant effects on cell proliferation, migration, and invasion. This study aims at revealing the association of Anxa2-Tyr23 phosphorylation in Anxa2-mediated acceleration of breast cancer progression and their elaborate molecular mechanisms.

Methods

Cell biological function experiments were performed to determine the effects of Anxa2-Tyr23 Phosphorylation on breast cancer cell proliferation and invasion in vitro and metastasis in vivo. The interaction of Tyr23 phosphorylated Anxa2 and STAT3 was verified by co-immunoprecipitation assay. Related mRNA and protein expression levels of cyclin D1 and MMP2/9 and phosphorylation level of STAT3 were detected.

Results

Anxa2-Tyr23 phosphorylation is necessary for proliferation, invasion, and metastasis of breast cancer cells in vitro and in vivo. Tyr23 phosphorylated Anxa2 binds and enhances the sensitivity of STAT3 activation in response to IL-6, thereby increasing the protein and mRNA expression levels of cyclin D1 and MMP2/9 which are STAT3 key target genes and serve pivotal regulatory functions in cell proliferation and invasion, respectively.

Conclusion

Our findings further confirmed the regulatory role of Anxa2 and revealed the direct relationship between Anxa2-Tyr23 phosphorylation and activation of STAT3. Moreover, this study provides novel insights into the function of Anxa2-Tyr23 phosphorylation in signal transduction for further understanding of the mechanism through which Anxa2 promotes the progression of breast cancer.