[Show abstract][Hide abstract] ABSTRACT: Background
Brain metastasis is an increasingly common complication for breast cancer patients; approximately 15– 30% of breast cancer patients develop brain metastasis. However, relatively little is known about how these metastases form, and what phenotypes are characteristic of cells with brain metastasizing potential. In this study, we show that the targeted knockdown of MMP-1 in breast cancer cells with enhanced brain metastatic ability not only reduced primary tumor growth, but also significantly inhibited brain metastasis.
Two variants of the MDA-MB-231 human breast cancer cell line selected for enhanced ability to form brain metastases in nude mice (231-BR and 231-BR3 cells) were found to express high levels of matrix metalloproteinase-1 (MMP-1). Short hairpin RNA-mediated stable knockdown of MMP-1 in 231-BR and 231-BR3 cells were established to analyze tumorigenic ability and metastatic ability.
Short hairpin RNA-mediated stable knockdown of MMP-1 inhibited the invasive ability of MDA-MB 231 variant cells in vitro, and inhibited breast cancer growth when the cells were injected into the mammary fat pad of nude mice. Reduction of MMP-1 expression significantly attenuated brain metastasis and lung metastasis formation following injection of cells into the left ventricle of the heart and tail vein, respectively. There were significantly fewer proliferating cells in brain metastases of cells with reduced MMP-1 expression. Furthermore, reduced MMP-1 expression was associated with decreased TGFα release and phospho-EGFR expression in 231-BR and BR3 cells.
Our results show that elevated expression of MMP-1 can promote the local growth and the formation of brain metastases by breast cancer cells.
BMC Cancer 12/2012; 12(1):583. DOI:10.1186/1471-2407-12-583 · 3.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A multifaceted strategy using a composite of anti-cancer nanotherapeutic and natural biomaterials silk fibroin (SF) and chitosan (CS) blend scaffolds was investigated for the treatment of a tissue defect post-tumor resection by providing local release of the therapeutic and filling of the defect site with the regenerative bioscaffolds. The scaffold-emodin nanoparticle composites were fabricated and characterized for drug entrapment and release, mechanical strength, and efficacy against GILM2 breast cancer cells in vitro and in vivo in a rat tumor model. Emodin nanoparticles were embedded in SF and SFCS scaffolds and the amount of emodin entrapment was a function of the scaffold composition and emodin loading concentration. In vitro, there was a burst release of emodin from all scaffolds during the first 2 days though it was detected even after 24 days. Increase in emodin concentration in the scaffolds decreased the overall elastic modulus and ultimate tensile strength of the scaffolds. After 6 weeks of in vivo implantation, the cell density (p < 0.05) and percent degradation (p < 0.01) within the remodeled no emodin SFCS scaffold was significantly higher than the emodin loaded SFCS scaffolds, although there was no significant difference in the amount of collagen deposition in the regenerated SFCS scaffold. The presence and release of emodin from the SFCS scaffolds inhibited the integration of SFCS into the adjacent tumor due to the formation of an interfacial barrier of connective tissue that was lacking in emodin-free SFCS scaffolds. While no significant difference in tumor size was observed between the in vivo tested groups, tumors treated with emodin loaded SFCS scaffolds had decreased presence and size and similar regeneration of new tissue as compared to no emodin SFCS scaffolds.
[Show abstract][Hide abstract] ABSTRACT: An approach that facilitates rapid isolation and characterization of tumor cells with enhanced metastatic potential is highly desirable. Here, we demonstrate that plating GI-101A human breast cancer cells on hard (0.9%) agar selects for the subpopulation of metastasis-initiating cells. The agar-selected cells, designated GI-AGR, were homogeneous for CD44(+) and CD133(+) and five times more invasive than the parental GI-101A cells. Moreover, mice injected with GI-AGR cells had significantly more experimental brain metastases and shorter overall survival than did mice injected with GI-101A cells. Comparative gene expression analysis revealed that GI-AGR cells were markedly distinct from the parental cells but shared an overlapping pattern of gene expression with the GI-101A subline GI-BRN, which was generated by repeated in vivo recycling of GI-101A cells in an experimental brain metastasis model. Data mining on 216 genes shared between GI-AGR and GI-BRN breast cancer cells suggested that the molecular phenotype of these cells is consistent with that of cancer stem cells and the aggressive basal subtype of breast cancer. Collectively, these results demonstrate that analysis of cell growth in a hard agar assay is a powerful tool for selecting metastasis-initiating cells in a heterogeneous population of breast cancer cells, and that such selected cells have properties similar to those of tumor cells that are selected based on their potential to form metastases in mice.
American Journal Of Pathology 05/2011; 178(5):2357-66. DOI:10.1016/j.ajpath.2011.01.047 · 4.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Trastuzumab shows remarkable efficacy in treatment of ErbB2-positive breast cancers when used alone or in combination with other chemotherapeutics. However, acquired resistance develops in most treated patients, necessitating alternate treatment strategies. Increased aerobic glycolysis is a hallmark of cancer and inhibition of glycolysis may offer a promising strategy to preferentially kill cancer cells. In this study, we investigated the antitumor effects of trastuzumab in combination with glycolysis inhibitors in ErbB2-positive breast cancer. We found that trastuzumab inhibits glycolysis via downregulation of heat shock factor 1 (HSF1) and lactate dehydrogenase A (LDH-A) in ErbB2-positive cancer cells, resulting in tumor growth inhibition. Moreover, increased glycolysis via HSF1 and LDH-A contributes to trastuzumab resistance. Importantly, we found that combining trastuzumab with glycolysis inhibition synergistically inhibited trastuzumab-sensitive and -resistant breast cancers in vitro and in vivo, due to more efficient inhibition of glycolysis. Taken together, our findings show how glycolysis inhibition can dramatically enhance the therapeutic efficacy of trastuzumab in ErbB2-positive breast cancers, potentially useful as a strategy to overcome trastuzumab resistance.
Cancer Research 04/2011; 71(13):4585-97. DOI:10.1158/0008-5472.CAN-11-0127 · 9.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Commentary to:Reevaluating Cathepsin D as a biomarker for breast cancer: Serum activity levels versus histopathologyDaniel E Abbott, Naira V Margaryan, Jacqueline Jeruss, Seema Khan, Virginia Kaklamani, David J Winchester, Nora Hansen, Alfred Rademaker, Zhila Khalkhali-Ellis and Mary J.C. Hendrix
[Show abstract][Hide abstract] ABSTRACT: The cellular and molecular pathways that regulate platelet activation, blood coagulation, and inflammation are emerging as
critical players in cancer progression and metastasis. Here, we demonstrate a novel signaling mechanism whereby protease-activated
receptor 1 (PAR1) mediates expression of melanoma cell adhesion molecule MCAM/MUC18 (MUC18), a critical marker of melanoma
metastasis, via activation of platelet-activating factor receptor (PAFR) and cAMP-responsive element-binding protein (CREB).
We found that PAR1 silencing with small hairpin RNA inhibits MUC18 expression in metastatic melanoma cells by inhibiting CREB
phosphorylation, activity, and binding to the MUC18 promoter. We further demonstrate that the PAF/PAFR pathway mediates MUC18
expression downstream of PAR1. Indeed, PAR1 silencing down-regulates PAFR expression and PAF production, PAFR silencing blocks
MUC18 expression, and re-expression of PAFR in PAR1-silenced cells rescues MUC18 expression. We further demonstrate that the
PAR1-PAFR-MUC18 pathway mediates melanoma cell adhesion to microvascular endothelial cells, transendothelial migration, and
metastatic retention in the lungs. Rescuing PAFR expression in PAR1-silenced cells fully restores metastatic phenotype of
melanoma, indicating that PAFR plays critical role in the molecular mechanism of PAR1 action. Our results link the two pro-inflammatory
G-protein-coupled receptors, PAR1 and PAFR, with the metastatic dissemination of melanoma and suggest that PAR1, PAFR, and
MUC18 are attractive therapeutic targets for preventing melanoma metastasis.
Journal of Biological Chemistry 10/2009; 284(42):28845-28855. · 4.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: At present, there is no efficient curative therapy for cancer patients with advanced metastatic disease. Targeting of antiapoptotic molecules acting on the mitochondrial apoptosis pathway could potentially augment antimetastatic effect of cytotoxic drugs. Similarly to Bcl-2 family members, beta-galactoside-binding lectin galectin-3 protects cancer cells from apoptosis induced by cytotoxic drugs through the mitochondrial pathway. In this study, we tested the hypothesis that inhibiting galectin-3 antiapoptotic function using a synthetic low-molecular weight carbohydrate-based compound lactulosyl-L-leucine (Lac-L-Leu) will augment apoptosis induced in human cancer cells by paclitaxel and increase its efficacy against established metastases. Treatment with synthetic glycoamine Lac-L-Leu alone reduced the number of established MDA-MB-435Lung2 pulmonary metastases 5.5-fold (P = .032) but did not significantly affect the incidence of metastasis. Treatment with paclitaxel alone (10 mg/kg three times with 3-day intervals) had no significant effect on the incidence or on the number of MDA-MB-435Lung2 metastases. Treatment with Lac-L-Leu/paclitaxel combination decreased both the number (P = .02) and the incidence (P = .001) of pulmonary metastases, causing a five-fold increase in the number of metastasis-free animals from 14% in the control group to 70% in the combination therapy group. The median number of lung metastases dropped to 0 in the combination therapy group compared with 11 in the control (P = .02). Synergistic inhibition of clonogenic survival and induction of apoptosis in metastatic cells by Lac-L-Leu/paclitaxel combination was functionally linked with an increase in mitochondrial damage and was sufficient for the antimetastatic activity that caused a reversal and eradication of advanced metastatic disease in 56% of experimental animals.
Neoplasia (New York, N.Y.) 10/2009; 11(9):901-9. DOI:10.1593/neo.09594 · 4.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The cellular and molecular pathways that regulate platelet activation, blood coagulation, and inflammation are emerging as critical players in cancer progression and metastasis. Here, we demonstrate a novel signaling mechanism whereby protease-activated receptor 1 (PAR1) mediates expression of melanoma cell adhesion molecule MCAM/MUC18 (MUC18), a critical marker of melanoma metastasis, via activation of platelet-activating factor receptor (PAFR) and cAMP-responsive element-binding protein (CREB). We found that PAR1 silencing with small hairpin RNA inhibits MUC18 expression in metastatic melanoma cells by inhibiting CREB phosphorylation, activity, and binding to the MUC18 promoter. We further demonstrate that the PAF/PAFR pathway mediates MUC18 expression downstream of PAR1. Indeed, PAR1 silencing down-regulates PAFR expression and PAF production, PAFR silencing blocks MUC18 expression, and re-expression of PAFR in PAR1-silenced cells rescues MUC18 expression. We further demonstrate that the PAR1-PAFR-MUC18 pathway mediates melanoma cell adhesion to microvascular endothelial cells, transendothelial migration, and metastatic retention in the lungs. Rescuing PAFR expression in PAR1-silenced cells fully restores metastatic phenotype of melanoma, indicating that PAFR plays critical role in the molecular mechanism of PAR1 action. Our results link the two pro-inflammatory G-protein-coupled receptors, PAR1 and PAFR, with the metastatic dissemination of melanoma and suggest that PAR1, PAFR, and MUC18 are attractive therapeutic targets for preventing melanoma metastasis.
[Show abstract][Hide abstract] ABSTRACT: Most anticancer agents activate nuclear factor kappa B (NF-kappaB), which can mediate cell survival, proliferation, and metastasis. Curcumin has been shown to inhibit the growth of various cancer cells, without toxicity to normal cells. The antitumor effects of curcumin could be due in part to the inactivation of NF-kappaB. We hypothesize that blocking NF-kappaB activity may augment paclitaxel cancer chemotherapy. In this study, we investigated whether the inactivation of NF-kappaB by curcumin would enhance the efficacy of paclitaxel for inhibiting breast cancer growth in vitro and in vivo. We confirmed that curcumin inhibited paclitaxel-induced activation of NF-kappaB and potentiated the growth inhibitory effect of paclitaxel in MDA-MB-231 breast cancer cells. The combination of curcumin with paclitaxel elicited significantly greater inhibition of cell growth and more apoptosis, compared with either agent alone. In an experimental breast cancer murine model using MDA-MB-231 cells, combination therapy with paclitaxel and curcumin significantly reduced tumor size and decreased tumor cell proliferation, increased apoptosis, and decreased the expression of matrix metalloprotease 9 compared with either agent alone. These results clearly suggest that a curcumin-paclitaxel combination could be a novel strategy for the treatment of breast cancer.
The Breast Journal 05/2009; 15(3):223-9. DOI:10.1111/j.1524-4741.2009.00709.x · 1.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Our recent study found that activation of signal transducer and activator of transcription 3 (Stat3) is up-regulated in human brain metastatic cells and contributes to brain metastasis of melanoma. However, the molecular mechanisms underlying this increased Stat3 activation and effect on brain metastasis are unknown. In this report, we showed that the expression of Janus-activated kinase 2 (JAK2), a Stat3 activator, was increased, whereas the expression of a negative regulator of Stat3, suppressor of cytokine signaling-1 (SOCS-1), was reduced in the brain metastatic melanoma cell line A375Br, relative to that in the parental A375P cell line. Consistently, SOCS-1 expression was also lower in the human brain metastatic tissues than in the primary melanoma tissues. Mechanistically, increased JAK2 expression in the A375Br cells was due to, at least in part, its decreased degradation, which was directly correlated with low expression of SOCS-1. Moreover, restoration of SOCS-1 expression resulted in the inhibition of Stat3 activation, whereas depletion of SOCS-1 up-regulated Stat3 activation. These clinical, experimental, and mechanistic findings strongly suggest that increased activation of Stat3 in brain metastatic melanoma cells might be due to decreased SOCS-1 expression. Furthermore, restoration of SOCS-1 expression in brain metastatic A375Br cells significantly inhibited brain metastasis in animal models (P<0.001). Additionally, alterations of SOCS-1 expression profoundly affected the expression of matrix metalloproteinase-2 (MMP-2), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) and the melanoma cell invasion and angiogenesis. Collectively, these data suggest that the loss of SOCS-1 expression is a critical event, leading to elevated Stat3 signaling and overexpression of MMP-2, bFGF, and VEGF, as well as enhanced invasion and angiogenesis of melanoma cells, consequently promoting brain metastasis.
Cancer Research 01/2009; 68(23):9634-42. DOI:10.1158/0008-5472.CAN-08-1429 · 9.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Podocalyxin is an anti-adhesive mucin-like transmembrane sialoglycoprotein that has been implicated in the development of aggressive forms of cancer. Podocalyxin is also known as keratan sulfate (KS) proteoglycan. Recently, we revealed that highly sulfated KS or another mucin-like transmembrane sialoglycoprotein podoplanin/aggrus is upregulated in malignant astrocytic tumors. The aim of this study is to examine the relationship between podocalyxin expression and malignant progression of astrocytic tumors. In this study, 51 astrocytic tumors were investigated for podocalyxin expression using immunohistochemistry, Western blot analysis, and quantitative real-time PCR. Immunohistochemistry detected podocalyxin on the surface of tumor cells in six of 14 anaplastic astrocytomas (42.9%) and in 17 of 31 glioblastomas (54.8%), especially around proliferating endothelial cells. In diffuse astrocytoma, podocalyxin expression was observed only in vascular endothelial cells. Podocalyxin might be associated with the malignant progression of astrocytic tumors, and be a useful prognostic marker for astrocytic tumors.
Biochemical and Biophysical Research Communications 09/2008; 374(2):394-8. DOI:10.1016/j.bbrc.2008.07.049 · 2.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Podoplanin (Aggrus) is a mucin-type sialoglycoprotein that is known as a useful marker for lymphatic endothelium and tumor-initiating cells (TICs). Interaction between podoplanin and C-type lectin-like receptor-2 (CLEC-2) is reported to be critical for podoplanin-induced platelet aggregation and cancer metastasis. Recently, several anti-human podoplanin antibodies have been created; however, these anti-podoplanin antibodies have not been well characterized. Five anti-podoplanin antibodies (NZ-1, D2-40, AB3, 18H5, and a rabbit polyclonal antibody) were investigated using ELISA, Western blot, and flow cytometry with synthesized podoplanin peptides and deletion mutants of recombinant podoplanin. The epitope of NZ-1 is platelet aggregation-stimulating (PLAG) domain-2/3; the epitope of D2-40, AB3, and 18H5 is PLAG1/2. The epitopes of D2-40 and AB3 are quite similar, although 18H5 is different from D2-40 and AB3. Using flow cytometric analysis, NZ-1 partially inhibited the interaction between podoplanin and CLEC-2, although other antibodies did not. In conclusion, the two most frequently used anti-podoplanin antibodies, D2-40 and AB3, have similar properties, although several studies have reported differences. NZ-1 neutralizes the interaction between podoplanin and CLEC-2, which may lead to the development of therapeutic antibodies against podoplanin-dependent cancer metastasis.
[Show abstract][Hide abstract] ABSTRACT: The potential of metastasis can be predicted from clinical features like tumor size, histologic grade, and gene expression patterns. We examined the whole-genome transcriptomic profile of a xenograft model of breast cancer to understand the characteristics of brain metastasis.
Variants of the MDA-MB-435 cell were established from experimental brain metastases. The LvBr2 variant was isolated from lesions in a mouse injected in the left ventricle of the heart, and these cells were used for two cycles of injection into the internal carotid artery and selection of brain lesions, resulting in the Br4 variant. To characterize the different metastatic variants, we examined the gene expression profile of MDA-MB-435, LvBr2, and Br4 cells using microarrays.
We could identify 2,016 differentially expressed genes in Br4 by using the F test. Various metastasis-related genes and a number of genes related to angiogenesis, migration, tumorigenesis, and cell cycle were differentially expressed by the Br4 cells. Notably, the Notch signaling pathway was activated in Br4, with increased Jag2 mRNA, activated Notch intracellular domain, and Notch intracellular domain/CLS promoter-luciferase activity. Br4 cells were more migratory and invasive than MDA-MB-435 cells in collagen and Matrigel Transwell assays, and the migration and invasion of Br4 cells were significantly inhibited by inactivation of Notch signaling using DAPT, a gamma-secretase inhibitor, and RNA interference-mediated knockdown of Jagged 2 and Notch1.
Taken together, these results suggest that we have isolated variants of a human cancer cell line with enhanced brain metastatic properties, and the activation of Notch signaling might play a crucial role in brain metastasis.
Clinical Cancer Research 08/2008; 14(13):4059-66. DOI:10.1158/1078-0432.CCR-07-4039 · 8.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We analyzed the differential gene expression between variants of MDA-MB-435 human breast cancer cell line that share an identical genetic background but have different metastatic ability. The major histocompatibility complex class II was found down-regulated in highly metastatic cells and correlated with MHC transactivator (CIITA) expression. Constitutive CIITA expression observed in poorly metastatic is driven by promoters III and IV of CIITA gene. Conversely, both promoters were ineffective in highly metastatic cells. The MHC class II and CIITA expression was restored in these cells upon stimulation with IFNgamma or by the treatment with a hypomethylating agent. Both treatments induced USF-1 and IRF binding complexes to promoter IV but only IFNgamma induced the binding of 435-Lung2 nuclear proteins to an ARE-1 site at the promoter III. Neither Southern blot nor bisulfite sequencing of promoter IV demonstrated strong hypermethylation of this promoter at the IFNgamma-responsive elements such as GAS, E-box or IRF-1. We suggest that partial or hemimethylation of promoter IV is sufficient to silence the CIITA expression in highly metastatic cells and that this epigenetic mechanism is responsible for the lack of MHC-II expression. Forced CIITA expression restored the MHC-II antigen expression in 435-Lung2 cells and abrogates spontaneous lung metastasis in both SCID and nude mice but also affected the tumorigenicity in nude mice. The increase in NK cell infiltration in nude mice bearing CIITA-tumors correlated with sign of tumor cell apoptosis and the increase in the number of NK cells in the spleens, suggesting that NK cells might be responsible for the observed antitumor activity.
The International Journal of Biochemistry & Cell Biology 02/2006; 38(4):544-62. DOI:10.1016/j.biocel.2005.07.012 · 4.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Galectin-3 is a multifunctional beta-galactoside-binding protein implicated in apoptosis, malignant transformation, and tumor progression. The mechanisms by which galectin-3 contributes to malignant progression are not fully understood. In this study, we found that the introduction of wild-type galectin-3 into nontumorigenic, galectin-3-null BT549 human breast epithelial cells conferred tumorigenicity and metastatic potential in nude mice, and that galectin-3 expressed by the cells was phosphorylated. In contrast, BT549 cells expressing galectin-3 incapable of being phosphorylated (Ser6-->Glu Ser6-->Ala) were nontumorigenic. A microarray analysis of 10,000 human genes, comparing BT549 transfectants expressing wild-type and those expressing phosphomutant galectin-3, identified 188 genes that were differentially expressed (>2.5-fold). Genes affected by introduction of wild-type phosphorylated but not phosphomutant galectin-3 included those involved in oxidative stress, a novel noncaspase lysosomal apoptotic pathway, cell cycle regulation, transcriptional activation, cytoskeleton remodeling, cell adhesion, and tumor invasion. The reliability of the microarray data was validated by real-time reverse transcription-PCR (RT-PCR) and by Western blot analysis, and clinical relevance was evaluated by real-time RT-PCR screening of a panel of matched pairs of breast tumors. Differentially regulated genes in breast cancers that are also predicted to be associated with phospho-galectin-3 in transformed BT549 cells include C-type lectin 2, insulin-like growth factor-binding protein 5, cathepsins L2, and cyclin D1. These data show the functional diversity of galectin-3 and suggest that phosphorylation of the protein is necessary for regulation (directly or indirectly) of unique sets of genes that play a role in malignant transformation.
Cancer Research 12/2005; 65(23):10767-75. DOI:10.1158/0008-5472.CAN-04-3333 · 9.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Currently, there is no effective therapy for metastatic breast cancer after surgery, radiation, and chemotherapy have been used against the primary tumor. Because curcumin suppresses nuclear factor-kappaB (NF-kappaB) activation and most chemotherapeutic agents activate NF-kappaB that mediates cell survival, proliferation, invasion, and metastasis, we hypothesized that curcumin would potentiate the effect of chemotherapy in advanced breast cancer and inhibit lung metastasis. We tested this hypothesis using paclitaxel (Taxol)-resistant breast cancer cells and a human breast cancer xenograft model. As examined by electrophoretic mobility gel shift assay, paclitaxel activated NF-kappaB in breast cancer cells and curcumin inhibited it; this inhibition was mediated through inhibition of IkappaBalpha kinase activation and IkappaBalpha phosphorylation and degradation. Curcumin also suppressed the paclitaxel-induced expression of antiapoptotic (XIAP, IAP-1, IAP-2, Bcl-2, and Bcl-xL), proliferative (cyclooxygenase 2, c-Myc, and cyclin D1), and metastatic proteins (vascular endothelial growth factor, matrix metalloproteinase-9, and intercellular adhesion molecule-1). It also enhanced apoptosis. In a human breast cancer xenograft model, dietary administration of curcumin significantly decreased the incidence of breast cancer metastasis to the lung and suppressed the expression of NF-kappaB, cyclooxygenase 2, and matrix metalloproteinase-9. Overall, our results indicate that curcumin, which is a pharmacologically safe compound, has a therapeutic potential in preventing breast cancer metastasis possibly through suppression of NF-kappaB and NF-kappaB-regulated gene products.
Clinical Cancer Research 11/2005; 11(20):7490-8. DOI:10.1158/1078-0432.CCR-05-1192 · 8.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Experimental evidence suggests that CXCR4, a Gi protein-coupled receptor for the ligand CXCL12/stromal cell-derived factor-1alpha (SDF-1alpha), plays a role in breast cancer metastasis. Transactivation of HER2-neu by G protein-coupled receptor activation has been reported as a ligand-independent mechanism of activating tyrosine kinase receptors. We found that SDF-1alpha transactivated HER2-neu in the breast cancer cell lines MDA-MB-361 and SKBR3, which express both CXCR4 and HER2-neu. AMD3100, a CXCR4 inhibitor, PKI 166, an epidermal growth factor receptor/HER2-neu tyrosine kinase inhibitor, and PP2, a Src kinase inhibitor, each blocked SDF-1alpha-induced HER2-neu phosphorylation. Blocking Src kinase, with PP2 or using a kinase-inactive Src construct, and inhibiting epidermal growth factor receptor/HER2-neu signaling with PKI 166 each inhibited SDF-1alpha-stimulated cell migration. We report a novel mechanism of HER2-neu transactivation through SDF-1alpha stimulation of CXCR4 that involves Src kinase activation.
Cancer Research 09/2005; 65(15):6493-7. DOI:10.1158/0008-5472.CAN-04-1303 · 9.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The chemokine receptors CCR7 and CXCR4 have been shown to play an important role in cancer metastasis. We therefore studied the differential expression of CCR7 and CXCR4, along with that of the biomarker HER2-neu, to evaluate whether these biomarkers could predict axillary lymph node metastasis in breast cancer.
Biomarker expression levels were evaluated using paraffin-embedded tissue sections of lymph node-negative (n = 99) and lymph node-positive (n = 98) T1 breast cancer by immunohistochemical staining.
Lymph node-positive tumors showed higher rates of high cytoplasmic CCR7 staining (21.5% versus 8.5%, P = 0.013) and HER2-neu overexpression (21.5% versus 9.3%, P = 0.019) than did lymph node-negative tumors. Similarly, high cytoplasmic CXCR4 expression occurred more commonly in lymph node-positive tumors (11.2% versus 5.1%, P = 0.113). In contrast, predominantly nuclear CXCR4 staining was more likely to be found in lymph node-negative tumors (54.5% versus 37.8%, P = 0.018). Furthermore, cytoplasmic CXCR4 coexpressed with HER2-neu was the only factor associated with involvement of four or more lymph nodes (16.7% versus 1.2%, P = 0.04) among lymph node-positive tumors. When all three biomarkers (CCR7, CXCR4, HER2-neu) were utilized together, 50.0% of lymph node-positive tumors highly expressed one of these biomarkers compared with 18.8% of the lymph node-negative tumors (P < 0.0001).
Our results suggest that the chemokine receptor CCR7 is a novel biomarker that can predict lymph node metastases in breast cancer. Utilization of additional markers, such as CXCR4 and HER2-neu, further improves the prediction of the presence and extent of lymph node involvement.
Clinical Cancer Research 08/2005; 11(16):5686-93. DOI:10.1158/1078-0432.CCR-05-0014 · 8.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metastasis is the primary cause of death from breast cancer. A xenograft model was used to identify genes potentially involved with metastasis, comparing expression in the poorly metastatic GI101A human breast cancer cell line and a highly metastatic variant, GILM2. cDNA microarray analyses of these isogenic variants were done using 16K Operon 70-mer oligonucleotide microarray slides. Differentially expressed genes were identified by ANOVA, and differences of > or =2.5-fold were found for 106 genes. Changes in protein or RNA expression were confirmed for 10 of 12 genes. Three markers, heat shock protein 70 (HSP-70), chemokine (C-X-C motif) ligand 1 (CXCL-1), and secreted leukocyte protease inhibitor (SLPI), were studied further with breast cancer tissue microarrays using a novel method of automated quantitative analysis. This uses cytokeratin to define pixels as breast cancer (tumor mask) within the tissue array spot and then measures intensity of marker expression using a cyanine 5-conjugated antibody within the mask. Scores were correlated with clinicopathologic variables. High HSP-70 expression and high nuclear CXCL-1 expression in primary tumors were both associated with decreased survival (P = 0.05 and 0.027, respectively). Expression of each marker was strongly associated with lymph node involvement (P = 0.0002, 0.008, 0.0012, and 0.012 for HSP-70, nuclear CXCL-1, cytoplasmic CXCL-1, and SLPI, respectively). Identification of genes associated with metastasis in experimental models may have clinical implications for the management of breast cancer, because some of these are associated with lymph node metastasis and survival and might be useful as prognostic markers or molecular targets for novel therapies.
Cancer Research 07/2005; 65(13):5578-87. DOI:10.1158/0008-5472.CAN-05-0108 · 9.33 Impact Factor