Increased invasive potential and up-regulation of MMP-2 in MDA-MB-231 breast cancer cells expressing the beta3 integrin subunit

Integrins are a family of transmembrane adhesion receptors that might transduce signals from the extracellular matrix into the inside of cells after ligand binding. In order to investigate whether beta3 integrins expressed in tumor cells might mediate such outside-in signaling, human MDA-MB-231 breast cancer cells that were stably transfected with either beta3 integrin or mock-transfected were investigated in a matrigel degradation assay and a grafting experiment was performed on the developing chicken chorioallantoic membrane (CAM). After cultivation on matrigel for time periods between one and five days, more matrigel was digested in the wells in which beta3 integrin expressing cells were incubated than in wells of mock-transfected cells. Furthermore, extracts of beta3 integrin expressing cells contained higher levels of MMP-2 protein as determined by immunoblotting and more MMP-2 associated gelatinase activity as detected by zymography than extracts of mock-transfected cells. Matrigel degradation and gelatinase activity as well as MMP-2 expression were elevated when beta3 integrin expressing cells were incubated in the presence of the RGD peptide (mimicking an integrin ligand). After grafting on 10 day-old embryonic chicken CAM for three to five days, beta3 integrin expressing cells assembled in spheroids showed higher rates of spreading on the CAM surface and CAM invasion as well as a significant MMP-2 up-regulation compared to mock-transfected cells. The results from the in vivo and in vitro experiments allow the conclusion that the presence of beta3 integrin in MDA-MB-231 breast cancer cells induced an increased MMP-2 expression and activity that might contribute to the enhanced invasive potential observed.     

Osteoblasts-derived TGF-beta1 enhance motility and integrin upregulation through Akt, ERK, and NF-kappaB-dependent pathway in human breast cancer cells

Bone metastases are common complications of breast cancer. Integrins are the major adhesive molecules in mammalian cells. Here we found that osteoblast conditioned medium (OBCM) increased the migration and cell surface expression of beta1 or beta3 integrin in human breast cancer cells (MDA-MB-231 cells). beta1 or beta3 integrin monoclonal antibodies (mAbs) or small interference RNA (siRNA) against beta1 or beta3 integrin inhibited the OBCM-induced increase in the migration of breast cancer cells. Transforming growth factor-beta1 (TGF-beta1) siRNA could remarkably blocked OBCM-induced chemomigration and beta1 and beta3 integrin expression in breast cancer cells. Stimulation of cells with OBCM caused an increase in Akt and extracellular signal-regulated kinase (ERK) phosphorylation in a time-dependent manner. In addition, treatment of MDA-MB-231 cells with phosphatidylinositol 3-kinase inhibitor (LY294002), ERK inhibitor (PD98059), NF-kappaB inhibitor (PDTC), or IkappaB protease inhibitor (TPCK) inhibited OBCM-induced cells migration and integrins expression. Treatment of MDA-MB-231 cells with OBCM induced IkappaB kinase alpha/beta (IKK alpha/beta) phosphorylation, IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 Ser(536) phosphorylation, and kappaB-luciferase activity. The OBCM-mediated increases in IKK alpha/beta phosphorylation, p65 Ser(536) phosphorylation, and kappaB-luciferase activity were inhibited by LY294002 and PD98059. In addition, TGF-beta1 siRNA also reduced the OBCM-induced ERK, Akt, IKKalpha/beta, IkappaBalpha, and p65 phosphorylation. Taken together, these results suggest that the osteoblast-derived TGF-beta1 acts through Akt and ERK, which in turn activates IKKalpha/beta and NF-kappaB, resulting in the activations of beta1 and beta3 integrins and contributing the migration of breast cancer cell.     

Migration-promoting role of VEGF-C and VEGF-C binding receptors in human breast cancer cells

Vascular endothelial growth factor C (VEGF-C) is a lymphangiogenic factor over-expressed in highly metastatic, cyclooxygenase (COX)-2 expressing breast cancer cells. We tested the hypothesis that tumour-derived VEGF-C may play an autocrine role in metastasis by promoting cellular motility through one or more VEGF-C-binding receptors VEGFR-2, VEGFR-3, neuropilin (NRP)-1, NRP-2, and integrin alpha9beta1. We investigated the expression of these receptors in several breast cancer cell lines (MDA-MB-231, Hs578T, SK-BR-3, T-47D, and MCF7) and their possible requirement in migration of two VEGF-C-secreting, highly metastatic lines MDA-MB-231 and Hs578T. While cell lines varied significantly in their expression of above VEGF-C receptors, migratory activity of MDA-MB-231 and Hs578T cells was linked to one or more of these receptors. Depletion of endogenous VEGF-C by treatments with a neutralising antibody, VEGF-C siRNA or inhibitors of Src, EGFR/Her2/neu and p38 MAP kinases which inhibited VEGF-C production, inhibited cellular migration, indicating the requirement of VEGF-C for migratory function. Migration was differentially attenuated by blocking or downregulation of different VEGF-C receptors, for example treatment with a VEGFR-2 tyrosine kinase inhibitor, NRP-1 and NRP-2 siRNA or alpha9beta1 integrin antibody, indicating the participation of one or more of the receptors in cell motility. This novel role of tumour-derived VEGF-C indicates that breast cancer metastasis can be promoted by coordinated stimulation of lymphangiogenesis and enhanced migratory activity of breast cancer cells.     

Culture of human breast cancer cell line (MDA-MB-231) on fibronectin-coated surface induces pro-matrix metalloproteinase-9 expression and activity

Interaction between cell surface integrin receptors with extracellular matrix (ECM) plays an important role in cell survival, proliferation, and migration including tumor development and invasion. Binding of ECM to integrins initiates intracellular signaling cascades, modulating expression and activity of different matrix metalloproteinases (MMPs) which is important in ECM degradation. The present study investigates fibronectin–integrin-mediated signaling and thereby modulation of MMPs expression and activity in human breast cancer cell line, MDA-MB-231. Culture of MDA-MB-231 cells on fibronectin (FN) induced expression and activity of pro-matrixmetalloproteinase-9 (MMP-9). Appreciable reduction of FN-induced pro-MMP-9 activity was observed in anti-α5 antibody treated cells. Inhibitor studies revealed that inhibitors of phosphatidyl inositiol-3-kinase (PI-3K), and nuclear factor kappa B (NF-κB) inhibited FN-induced pro-MMP-9 activity. FN increased tyrosine phosphorylation of focal adhesion kinase (FAK), integrin linked kinase (ILK), and PI-3K in MDA-MB-231 cells. FN-induced the transactivation of MMP-9 promoter by enhancing DNA binding activity of NF-κB and Sp1. Wound healing assay showed faster migration of MDA-MB-231cells grown on fibronectin-coated as surface as compared to control. Our findings indicated that culture of MDA-MB-231 on fibronectin perhaps send signals via fibronectin–integrin-mediated signaling pathways recruiting FAK, PI-3K, ILK, NF-κB, and modulate expression and activation of pro-MMP-9. These observations may enrich fundamental aspects of cancer biology especially role of α5β1 integrin in regulation of MMPs expression and activity.     

Histone deacetylases 1, 6 and 8 are critical for invasion in breast cancer

Histone deacetylases (HDACs) are associated with the development and progression of cancer, but it is not known which of the HDAC isoforms play important roles in breast cancer metastasis. This study identified the specific HDAC isoforms that are necessary for invasion and/or migration in human breast cancer cell lines. MDA-MB-231 cells were significantly more invasive and expressed higher levels of matrix metalloproteinase-9 (MMP-9) compared to MCF-7 cells. We compared the expression of HDAC isoforms between MCF-7 and MDA-MB-231 cells and found greater expression of HDAC4, 6 and 8 in MDA-MB-231 cells by RT-PCR and Western blot analyses. In addition, apicidin, a histone deacetylase inhibitor, was shown to attenuate the invasion, migration and MMP-9 expression in MDA-MB-231 cells. Using specific siRNAs directed against HDAC1, 4, 6 and 8, we show that inhibition of HDAC1, 6 and 8, but not HDAC4, are responsible for invasion and MMP-9 expression in MDA-MB-231 cells. We analyzed the invasiveness of MCF-7 cells overexpressing HDAC1, 4, 6 or 8 and found that overexpression of HDAC1, 6 or 8 increased invasion and MMP-9 expression. By developing HDAC isoforms as potential biomarkers for breast cancer metastasis, the present study can be extended to developing therapies for breast cancer invasion.     

Expression of Ets-related transcription factors and matrix metalloproteinase genes in human breast cancer cells

The expression levels of ets and MMP genes was examined in two breast cancer cell lines of differing invasive potential. The more invasive MDA-MB-231 cell line had higher levels of Ets-1, Ets-2, PEA3, ERM, Tel, Net, MMP-13 and -14 mRNA than MCF-7 cells. MMP-1, -3 and -16 mRNAs were expressed equally. TPA stimulated MMP-1, -9 and TIMP-1 mRNA expression in both cell lines. MMP-2 and MMP-7 mRNAs were not detected in either cell line. The Ets-1 protein was only detected in MDA-MB-231 cells and its level increased following TPA stimulation. TPA induced MMP-9 activity in MCF-7 cells and increased its activity in MDA-MB-231 cells, however, MMP-2 activity was not detected.     

TAGLN基因过表达对乳腺癌细胞迁移和侵袭能力的影响

目的 研究TAGLN基因过表达对人乳腺癌细胞MDA-MB-231迁移能力和侵袭能力的影响及其分子机制.方法 对MDA-MB-231细胞采用慢病毒表达系统构建TAGLN基因稳定过表达细胞株,将MDA-MB-231细胞正常培养设为空白对照组,空载体慢病毒包装感染MDA-MB-231细胞后获得的稳定转染细胞株设为空载体对照组.Real time PCR和Western blot检测TAGLN mRNA和蛋白表达,划痕实验和Transwell侵袭实验检测细胞迁移和侵袭能力,Western blot检测TAGLN基因过表达后基质金属蛋白酶2(matrix metalloproteinase-2,MMP-2)和MMP-9蛋白表达变化.结果 MDA-MB-231细胞感染TAGLN基因过表达慢病毒载体后,细胞中TAGLN mRNA表达和蛋白表达升高(均P＜0.01),成功构建TAGLN基因过表达稳定细胞株(231-TAGLN).231-TAGLN细胞的体外迁移能力和侵袭能力下降,与空载体对照组和空白对照组细胞比较,差异均具有统计学意义(均P＜0.01),同时伴有MMP-2和MMP-9表达水平降低(均P＜0.01).结论 TAGLN基因过表达可以抑制乳腺癌细胞的迁移和侵袭,MMP-2和MMP-9基因表达下降可能参与这一过程.     

Roles for GP IIb/IIIa and αvβ3 integrins in MDA-MB-231 cell invasion and shear flow-induced cancer cell mechanotransduction

Adhesion of cancer cell to endothelial cells and the subsequent trans-endothelial migration are key steps in hematogenous metastasis. However, the molecular mechanisms of cancer cell/endothelial cell interaction under hemodynamic shear flow and how shear flow-induced cancer cell mechanotransduction are yet to be fully defined. In this study, we identified that the integrins of both platelet glycoprotein IIb/IIIa (GP IIb/IIIa) and αvβ3 were crucial for hematogenous metastasis of human breast carcinoma MDA-MB-231cells. The cell migration and invasion were studied by using Millicell cell culture insert system. The numbers of invaded MDA-MB-231 cells significantly increased by thrombin-activated platelets and reduced by eptifibatide, a platelet inhibitor. Meanwhile, RGDWE peptides, a specific inhibitor of αvβ3 integrin, also inhibited MDA-MB-231 cell invasion. We further used a parallel-plate flow chamber to investigate MDA-MB-231 cell adhesion under flow conditions. Alike in static condition, the adhesion capability of MDA-MB-231 cells to endothelial monolayer was also significantly affected by GP IIb/IIIa and αvβ3 integrins. The expression of matrix metalloproteinase-2 (MMP-2), MMP-9 and αvβ3 integrin in MDA-MB-231 cells were up-regulated after low shear stress exposure (1.84 dynes/cm², 2 h). Moreover, we also demonstrated that low shear stress induced a sustained activation of p85 (a regulatory subunit of PI3K) and Akt. Pre-treating MDA-MB-231 cells with the specific PI3K inhibitor of LY294002 abolished the shear stress induced-Akt activation, and the expression of MMP-2, MMP-9, vascular endothelial growth factor (VEGF) and αvβ3 integrin were also down-regulated. Immunofluorescence assay showed that low shear stress also induced αvβ3 integrin clustering and nuclear factor-κB (NF-κB) activation. Interestingly, shear stress-induced activation of Akt and NF-κB was attenuated by LM609, a specific antibody of αvβ3 integrin. It suggests that αvβ3 integrin might be as a mechanosensor to trigger both PI3K/Akt and NF-κB signaling pathways. Taken together, these results establish that GP IIb/IIIa and αvβ3 integrins are essential mediators, and provide insight into how shear stress-induced αvβ3 integrin activation and the downstream pathways for contribution to MDA-MB-231 cell adhesion, migration and invasion.     

Flavonoid baicalein suppresses adhesion,migration and invasion of MDA-MB-231 human breast cancer cells

Baicalein is a widely used Chinese herbal medicine that has been used historically in anti-inflammatory and anti-cancer therapy. However, the molecular mechanism of its anti-cancer activity remains poorly understood and warrants further investigations. The purpose of this study is to verify the activity of baicalein to inhibit the invasion of MDA-MB-231 human breast cancer cells. The results indicated that baicalein suppressed MDA-MB-231 cell adhesion to fibronectin-coated substrate, wound healing migration and invasion through the Matrigel in a concentration-dependent manner. Western blot and gelatin zymography analysis showed that baicalein significantly inhibited the expression and secretion of matrix metalloproteinases 2/9 (MMP-2/9) in MDA-MB-231 cells. Additionally, treatment of MDA-MB-231 cells with baicalein down-regulated the expression of MMP-2/9 involved mitogen-activated protein kinases (MAPK) signaling pathway. Taken together, baicalein had potential to suppress the adhesion, migration and invasion of MDA-MB-231 cancer cells in vitro and it could serve as a promising drug for the treatment of cancer metastasis.     

MUC1的表达与乳腺癌细胞粘附的关系

背景与目的:近年研究认为,肿瘤的转移与肿瘤细胞膜上粘液型糖蛋白的大量形成有关。本实验研究糖基化抑制剂苯甲基-α-N-乙酰半乳糖胺对粘蛋白-1(mucin1,MUC1)形成的抑制作用及其对乳腺癌细胞株MDA-MB-231细胞的粘附、侵袭转移能力的影响。方法:免疫细胞化学法检测MUC1表达,噻唑蓝比色法(MTT)检测细胞对人工基底膜(Matrigel)的粘附能力,明胶酶谱法(zymography)检测MDA-MB-231细胞MMP-2、MMP-9的分泌变化。结果:经苯甲基-α-N-乙酰半乳糖胺去糖基化处理后的肿瘤细胞组与相应对照组比较,MUC1表达降低,对基底膜的粘附力明显降低(P<0.01),同时细胞中MMP-2和MMP-9的分泌量显著下降。结论:MUC1表达水平与肿瘤细胞的粘附能力相关,MUC1的抑制使乳腺癌MDA-MB-231细胞粘附能力,分泌Ⅳ型胶原酶能力明显减弱。     

Transforming growth factor-β1 enhances the invasiveness of human MDA-MB-231 breast cancer cells by up-regulating urokinase activity

Transforming growth factor-beta (TGFβ1) enhances human MDA-MB-231 breast tumour cell invasion of reconstituted basement membrane in vitro but does not inhibit proliferation of this cell line. In contrast to basal invasion, which is plasmin-, urokinase (uPA)-, tissue-type plasminogen activator (t-PA)-, matrix metalloproteinase (MMP)-9- and TIMP-1-inhibitable MMP-dependent, TGFβ1 enhanced-invasion is dependent upon plasmin and uPA activity but does not appear to involve t-PA-, MMP9- or TIMP-1-inhibitable MMPs, as judged by inhibitor studies. Enhanced invasion is associated with increased u-PA, UPAR, PAI-1, MT-MMP-1, MMP-9 and TIMP-1 expression; with reduced t-PA, MMP-1 and MMP-3 expression; and with the induction of membrane MMP-9 association. The net result of these changes includes increased secreted, but not membrane-associated, uPA levels and activity and reduced secreted levels of plasmin and APMA-activatable gelatinolytic, collagenolytic and caseinolytic MMP activity but no change in membrane-associated gelatinolytic activity, despite increased MT-MMP-1 expression and MMP-9 membrane association. TGFβ1 does not induce MMP-2 expression. Our data indicate that TGFβ1 can promote the malignant behaviour of MDA-MB-231 cells refractory to TGFβ1-mediated proliferation control by enhancing their invasive capacity. We suggest that this results from the action of a uPA/plasmin-dependent mechanism resulting from stimulation of uPA expression, secretion and subsequent activity, despite elevated PAI-1 inhibitor levels. Int. J. Cancer 75:721–730, 1998.© 1998 Wiley-Liss, Inc.     

过表达lncRNA LINC00886靶向调控miR-451a影响乳腺癌MDA-MB-231细胞生物学行为

目的:探究过表达长链非编码RNA（lncRNA）LINC00886通过调控微小RNA-451a（miR-451a）对乳腺癌（BC）MDA-MB-231细胞生物学行为的影响。方法:荧光定量PCR（qRT-PCR）检测人乳腺上皮细胞系（MCF-12A）和4种BC细胞系（HCC1937、SUM159、SK-BR-3和MDA-MB-231）中lncRNA LINC00886、miR-451a表达。将MDA-MB-231细胞分为对照组、LINC00886-NC组、LINC00886组、LINC00886+miR-NC组、LINC00886+miR-451a组。qRT-PCR法检测MDA-MB-231细胞中lncRNA LINC00886、miR-451a表达水平;克隆形成实验和EdU染色检测MDA-MB-231细胞增殖能力;流式细胞术、Transwell小室实验、划痕愈合实验分别用来检测MDA-MB-231细胞凋亡、侵袭、迁移;蛋白印迹法检测MDA-MB-231细胞中增殖细胞核抗原（PCNA）、Bcl-2相关X蛋白（Bax）、B淋巴细胞瘤-2（Bcl-2）、活化的半胱氨酸天冬氨酸蛋白酶3（Cleaved caspase-3）、基质金属蛋白酶（MMP）-2、MMP-9蛋白表达;双荧光素酶报告基因检测lncRNA LINC00886与miR-451a的靶向关系。结果:与人乳腺上皮细胞MCF-12A相比,BC细胞系中lncRNA LINC00886表达水平降低,miR-451a表达水平升高（P＜0.05）;过表达lncRNA LINC00886可升高MDA-MB-231细胞凋亡率、Bax和Cleaved caspase-3蛋白表达,降低miR-451a表达、集落形成数、EdU阳性细胞百分比、侵袭细胞数、迁移率以及PCNA、Bcl-2、MMP-2、MMP-9蛋白表达（P＜0.05）;上调miR-451a表达可减弱lncRNA LINC00886过表达对MDA-MB-231细胞的影响（P＜0.05）;lncRNA LINC00886可靶向调控miR-451a表达。结论:过表达lncRNA LINC00886可通过靶向抑制miR-451a表达促进MDA-MB-231细胞凋亡并抑制MDA-MB-231细胞增殖、侵袭和迁移。     

Matrix-directed regulation of pericellular proteolysis and tumor progression

The microenvironment of cancer cells, composed of extracellular matrix (ECM) macromolecules, plays a pivotal function in tumor progression. ECM preexisting modules or cryptic sites revealed by partial enzymatic hydrolysis positively or negatively regulate matrix metalloproteinase (MMP) expression and activation, further influencing matrix invasion by cancer cells. Pericellular activation of gelatinase A (MMP-2) proceeds via the formation of a complex involving its inhibitor, TIMP-2, its activator(s), MT-MMPs and alphavbeta3 integrin forming a docking system. This proteinase has been invariably linked to cancer cell invasive potential and is often predictive of a poor survival. MMP-2 degrades most ECM macromolecules and appears to act as a main 'decryptase'. ECM modulation of MMP-2 activation pathway thus influences angiogenesis and tumor growth. For instance the noncollagenous domain of alpha3 chain of type IV collagen, through alphavbeta3 integrin binding, inhibits both MT1-MMP and alphavbeta3 integrin expression from melanoma cells and empedes cell migration and proliferation. At the opposite, a particular module in elastin (VGVAPG) with type VIII beta turn conformation stimulates MT1-MMP and proMMP-2 activation through binding to S-gal elastin receptor, and increases the matrix invasive capacity of several cancer cell lines and endothelial cells. Endocytosis emerges as a main mechanism controlling MMP-2, and also other MMPs; it proceeds via the formation of a MMP-thrombospondin(s) complex further recognized by the LRP scavenger receptor. ECM undergoes conspicuous variations with aging linked to alterations of tissue organization and post-translational modifications of matrix constituents that modify cell-matrix interactions and MMP-2 activation pathway.     

Positive regulation of migration and invasion by vasodilator-stimulated phosphoprotein via Rac1 pathway in human breast cancer cells

This study aimed to investigate the role of the cytoskeleton-associated protein vasodilator-stimulated phosphoprotein (VASP) on the migration and invasion of human breast cancer cells and its relationship to Rac1 which is a member of the Rho family and has been found to be implicated in tumorigenesis, invasion and metastasis. We detected the mRNA and protein expression levels of VASP and Rac1 of the non-invasive breast cancer cell line MCF-7 as well as the invasive cell line MDA-MB-231 by RT-PCR and Western blotting. GST pull-down assay was used to examine the activitiy of Rac1. Accordingly, the cell invasive migration ability was analyzed in a wound-healing assay (2D) and transwell assays (3D migration and invasion). We then used VASP-siRNA to inhibit the expression of VASP in breast cancer cells in order to study the relationship between the VASP expression level and the invasive migration ability of breast cancer cells. Rac1-siRNA was used to decrease the expression of Rac1, and observe its effect on the VASP expression level together with the migration and invasion ability of MCF-7 and MDA-MB-231 cells. Our results revealed that the invasive breast cancer cell line MDA-MB-231 showed a higher Rac1 activity and VASP expression level compared with the non-invasive MCF-7. Inhibition of Rac1 or VASP by siRNA, respectively, decreased the migration and invasion ability of breast cancer cells and the transfection of Rac1 siRNA-mediated reduction of VASP expression at mRNA and protein levels. Collectively, our data showed that the higher expression level of VASP contributed to a higher invasive migration capacity of human breast cancer cells which was controlled by the Rac1 pathway.     

AlphaVbeta3 integrin regulates heregulin (HRG)-induced cell proliferation and survival in breast cancer

alpha(v)beta(3) integrin-overexpression in tumor associated vasculature is a marker of poor prognosis in breast cancer. A positive correlation between alpha(v)beta(3) integrin and overexpression of Heregulin (HRG), a growth factor associated with breast cancer aggressiveness was recently demonstrated. Here, we addressed the role of alpha(v)beta(3) in the proliferation and survival of HRG-overexpressing breast cancer models. Expression of the RGD-binding integrins alpha(v)beta(3), alpha(v)beta(5) and alpha(v)beta(6) was assessed in the HRG-overexpressing breast cancer cells MDA-MB-231, Hs578T (231/WT and Hs578T/WT, respectively) and derived cells transfected with the antisense orientation of the HRG-beta2 full-length cDNA (231/ASPOOL, 231/AS31 and Hs578T/AS15). Interestingly, only alpha(v)beta(3) expression was noticeably decreased by blockade of HRG expression in the 231/ASPOOL, 231/AS31 and Hs578T/AS15 cells. Small RGD-based peptidomimetic alpha(v)beta(3) antagonists significantly decreased cell viability and anchorage-dependent cell growth of HRG-overexpressing cells, while the low-HRG-expressing 231/AS31 cells did not show a significant response. Mechanistically, functional blockade of alpha(v)beta(3) impaired HRG-promoted hyperactivation of ERK1/ERK2 MAPK without altering the activation of AKT. Flow cytometric analysis of the cell cycle demonstrated that alpha(v)beta(3) antagonists significantly decreased S- and G2/M-phase subpopulations of 231/WT and control 231/VEC cells. Comparable, this effect was linked to an increase in the levels and nuclear translocation of the CDKs inhibitor p27(Kip1). Besides downregulating alpha(v)beta(3) and its driven signaling, HRG blockade led to decreased levels of CYR61 in 231/ASPOOL and 231/AS31 cells. Considering that CYR61 is sufficient to upregulate the expression of alpha(v)beta(3), we then assessed alpha(v)beta(3) levels in MDA-MB-231 cell derivatives expressing the antisense orientation of the CYR61 cDNA (231/CYR61AS-5 and 231/CYR61AS-8). Remarkably, downregulation of CYR61 drastically decreased the levels of alpha(v)beta(3) in the 231/CYR61-5 and 231/CYR61-8 cells, providing further evidence of a key role for CYR61 in HRG-dependent alpha(v)beta(3) overexpression. Moreover, blockade of CYR61 expression impaired the HRG-induced hyperactivation of ERK1/ERK2 MAPK without altering the activation status of AKT in MDA-MB-231 cells, thus resembling the effects exerted by the downregulation of HRG expression as well as by functional blockade of alpha(v)beta(3). These results indicate that HRG is regulating alpha(v)beta(3) levels as well as alpha(v)beta(3)-triggered signaling through its downstream effector, CYR61, in highly invasive breast cancer cells. Altogether, the data presented here provide evidence of a CYR61-regulatory role on alpha(v)beta(3) integrin expression in the modulation of uncontrolled growth of HRG-overexpressing breast carcinomas. This work supports additional studies concerning the use of integrin antagonists as dual therapeutic agents in breast cancer, targeting both, endothelial and tumor cells.     

JAK/STAT3和MAPK/ERK在乳腺癌细胞侵袭转移中的交互作用及意义

目的研究应用JAK酶抑制剂AG490对乳腺癌细胞MDA-MB-231 STAT3和ERK磷酸化的影响,初步探讨JAK/STAT3和MAPK/ERK两条信号转导通路的交互作用以及在乳腺癌细胞侵袭转移中的调控意义。方法以JAK酶抑制剂AG490处理乳腺癌细胞MDA-MB-231,Western blot检测细胞中P-STAT3、P-ERK蛋白水平变化;RT-PCR检测细胞中STAT3、ERK1、ERK2mRNA的变化;明胶酶谱法检测细胞分泌MMP-2、MMP-9的变化,Transwell小室进行人工重组基底膜侵袭和运动实验。结果应用JAK酶抑制剂AG490后人乳腺癌细胞MDA-MB-231中P-STAT3、P-ERK蛋白均减少,STAT3、ERK1、ERK2mRNA表达下降,同时可使细胞分泌MMP-2、MMP-9减少,使细胞侵袭、迁移能力降低。结论JAK/STAT3和MAPK/ERK两条信号转导通路之间存在交互作用,通过JAK酶抑制可改变转录因子STAT3和激酶ERK磷酸化水平,进而可以交互影响其基因转录的表达。JAK酶抑制对两条信号转导通路的激活有阻断作用而可以抑制乳腺癌细胞的侵袭转移。     

A specific sequence of the noncollagenous domain of the alpha3(IV) chain of type IV collagen inhibits expression and activation of matrix metalloproteinases by tumor cells

The invasive properties of melanoma cells correlate with the expression of matrix metalloproteinases (MMPs) and their physiological modulators (tissue inhibitors of metalloproteinase and membrane-type MMPs) and with that of the alphaVbeta3 integrin. We investigated the effect of anterior lens capsule type IV collagen and of the alpha3(IV) collagen chain on the invasive properties of various tumor cell lines (HT-144 melanoma cells, HT-1080 fibrosarcoma cells). We demonstrated that anterior lens capsule type IV collagen or specifically the synthetic peptide alpha3(IV) 185-203 inhibited both the migration of melanoma or fibrosarcoma cells as well as the activation of membrane-bound MMP-2 by decreasing the expressions of MT1-MMP and the beta3 integrin subunit.     

Identification of the functional role of AF1Q in the progression of breast cancer

A novel highly metastatic MDA-MB-231HM cells, derived from MDA-MB-231, was established in our institute. RT-PCR, real-time PCR and Western blot showed that AF1Q gene was differentially expressed between highly metastatic MDA-MB-231HM cells and its parental MDA-MB-231 cells. However, its molecular mechanisms in breast cancer metastasis remain to be characterized. To investigate the effects of AF1Q on the progression of human breast cancer cells, in the present study, recombinant expression plasmid vectors of the human AF1Q gene was transfected into MDA-MB-231 cells. We demonstrated that AF1Q overexpression enhanced the in vitro proliferation and invasive potential of breast cancer cells. Focused microarray analyses showed that 22 genes were differentially expressed between AF1Q transfected cells and its parental counterparts. Integrin alpha3, accompanied by up-regulation of Ets-1 and MMP-2, significantly enhanced the in vitro invasive potential of human breast cancer cells mediated by AF1Q. Estrogen-responsive ring finger protein gene (EFP), also played a role in the enhancement of in vitro proliferation of human breast cancer cells mediated by AF1Q, accompanied by down-regulation of 14-3-3delta. The association was ERalpha independent. These results were further demonstrated by RNA interference (RNAi) experiment in vitro. In in vivo study, we also demonstrated that AF1Q transfected breast cancer cells grew much faster and had more pulmonary metastases than vector-transfected or its parental counterparts. On the contrary, AF1Q knockdown cells grew slower and had less pulmonary metastasis. Similar effects of AF1Q on integrin alpha3, Ets-1, MMP-2, EFP, and 14-3-3delta expression observed in vitro studies were also found in the in vivo study. Taken together, these results provide functional evidences that overexpression of AF1Q leads to a more progression in human breast cancer, at least in part, through regulating the integrin alpha3, Ets-1, MMP-2, EFP, and 14-3-3delta expression.