Enhanced Breast Cancer Cell Invasion Research Articles

Compression enhances invasive phenotype and matrix degradation of breast cancer cells via Piezo1 activation

BackgroundUncontrolled growth in solid breast cancer generates mechanical compression that may drive the cancer cells into a more invasive phenotype, but little is known about how such compression affects the key events and corresponding regulatory mechanisms associated with invasion of breast cancer cells including cellular behaviors and matrix degradation.ResultsHere we show that compression enhanced invasion and matrix degradation of breast cancer cells. We also identified Piezo1 as the putative mechanosensitive cellular component that transmitted compression to not only enhance the invasive phenotype, but also induce calcium influx and downstream Src signaling. Furthermore, we demonstrated that Piezo1 was mainly localized in caveolae, and both Piezo1 expression and compression-enhanced invasive phenotype of the breast cancer cells were reduced when caveolar integrity was compromised by either knocking down caveolin1 expression or depleting cholesterol content.ConclusionsTaken together, our data indicate that mechanical compression activates Piezo1 channels to mediate enhanced breast cancer cell invasion, which involves both cellular events and matrix degradation. This may be a critical mechanotransduction pathway during breast cancer metastasis, and thus potentially a novel therapeutic target for the disease.

Integrin α3β1 Represses Reelin Expression in Breast Cancer Cells to Promote Invasion.

Simple SummaryBreast cancer remains the second leading cause of cancer-related deaths in women, and about 1 in 8 women in the United States develops invasive breast cancer in her lifetime. Integrin α3β1 has been linked to breast cancer progression, but mechanisms whereby it promotes tumor invasion remain unclear. The goal of our study was to determine how α3β1 drives invasion, towards exploiting this integrin as a therapeutic target for breast cancer. We found that α3β1 represses the expression of Reelin, a secreted glycoprotein that inhibits invasion and for which loss of expression is associated with poor prognosis in breast cancer. We also show that increased Reelin expression following RNAi-mediated suppression of α3β1 causes a significant decrease in breast cancer cell invasion. Our findings demonstrate a critical role for α3β1 in promoting cell invasion through repression of Reelin, highlighting the potential value of this integrin as a therapeutic target for breast cancer.Integrin α3β1, a cell adhesion receptor for certain laminins, is known to promote breast tumor growth and invasion. Our previous gene microarray study showed that the RELN gene, which encodes the extracellular glycoprotein Reelin, was upregulated in α3β1-deficient (i.e., α3 knockdown) MDA-MB-231 cells. In breast cancer, reduced RELN expression is associated with increased invasion and poor prognosis. In this study we demonstrate that α3β1 represses RELN expression to enhance breast cancer cell invasion. RELN mRNA was significantly increased upon RNAi-mediated α3 knockdown in two triple-negative breast cancer cell lines, MDA-MB-231 and SUM159. Modulation of baseline Reelin levels altered invasive potential, where enhanced Reelin expression in MDA-MB-231 cells reduced invasion, while RNAi-mediated suppression of Reelin in SUM159 cells increased invasion. Moreover, treatment of α3β1-expressing MDA-MB-231 cells with culture medium that was conditioned by α3 knockdown MDA-MB-231 cells led to decreased invasion. RNAi-mediated suppression of Reelin in α3 knockdown MDA-MB-231 cells mitigated this effect of conditioned-medium, identifying secreted Reelin as an inhibitor of cell invasion. These results demonstrate a novel role for α3β1 in repressing Reelin in breast cancer cells to promote invasion, supporting this integrin as a potential therapeutic target.

MiR-423 Promotes Breast Cancer Invasion by Activating NF-κB Signaling.

ObjectiveBreast cancer has become the most common malignancy among women worldwide; therefore, novel diagnostic and prognostic markers and therapeutic targets are urgently required. NF-κB signaling plays a pivotal role in enhancing breast cancer malignant phenotypes, especially cancer invasion and metastasis, which is the main cause of death in cancer patients. TNIP2, an important inhibitor of the NF-κB pathway, is known to involve a negative feedback loop of the NF-κB signaling cascade and to regulate tumor aggressiveness in various cancer types. However, the mRNA level of TNIP2 is barely altered in breast cancer; thus, the mechanism that regulates TNIP2 in breast cancer still needs to be elucidated.MethodsWe analyzed the expression and prognosis of miR-423 in a TCGA BRCA miRNA cohort and in clinical specimens. We detected the invasive capacity through a Matrigel-coated Transwell penetration assay, a three-dimensional (3D) spheroid invasion assay and a wound healing assay. Then, we applied luciferase assays, real-time PCR assays and Western blotting to further study the mechanism.ResultsIn this study, analysis of the TCGA BRCA miRNA cohort and clinical specimens demonstrated that miR-423 was upregulated in human breast cancers and was positively correlated with clinical stage, poor overall survival and metastasis classification. Moreover, the invasiveness of breast cancer cells was enhanced by ectopic expression of miR-423 and inhibited by miR-423 downregulation. Mechanistically, upregulation of miR-423 led to activation of the NF-κB signaling pathway and elevated expression of snail and twist, while repression of miR-423 inhibited this pathway. Furthermore, the results indicated that TNIP2 is a target gene of miR-423, and suppression of TNIP2 resulted in increased invasiveness in miR-423-silenced cells.ConclusionOur results suggest that miR-423 is a crucial factor that enhances breast cancer cell invasion through the NF-κB signaling pathway and shed light on miR-423 as a promising prognostic and therapeutic marker for metastatic breast cancer.

Abstract 4518: IL-4/IL-13 stimulated tumor-associated macrophages enhance breast cancer cell invasion through Rho-GTPase signaling

Abstract The high metastatic potential of inflammatory and other aggressive breast cancer is the major determinant of mortality. Recently, it has become clear that signals from the tumor microenvironment (TME) harbor the capacity to enhance cancer cell dissemination. Of the various cells that comprise the TME, macrophages are the most abundant in solid tumors. Therefore, we aimed to better understand the relationship between macrophage-breast cancer cell crosstalk. Intriguingly, in our previous work we showed that inflammatory breast cancer (IBC) cells are hyper-migratory in response to macrophage conditioned media. Additionally, we found this process is regulated by the Rho-GTPase, RhoC. Recent advances in tumor associated macrophage (TAM) biology have led to the understanding that TAM populations in the TME are diverse, primarily due to directional differentiation promoted by unique secreted components from the various cells in the TME. Therefore, this study aimed to understand which subpopulation of M2-like TAMs had the greatest impact on breast cancer cell aggressiveness. Our data show that stimulation of the triple negative breast cancer (TNBC) cell model, MDA-MB-231, and the IBC TNBC cell line, SUM-149, with media extracts from IL-4/IL-13 stimulated M2 macrophages (M2a) elicit the strongest migratory and invasive responses. Subsequently, we stimulated RhoA or RhoC knockout (CRISPR) MDA-231 and SUM-149 cells with M2a conditioned media to address their role in regulating migratory/invasive responses. In brief, we find that RhoA and RhoC, in part, regulate M2a-TAM induced responses. Secretome analysis of M2a-TAM conditioned media reveals high levels of vascular endothelial growth factor (VEGF) and chemokine (C-C motif) ligand 18 (CCL-18). Functional studies suggest that VEGF and CCL-18 synergistically enhance cellular invasiveness. Moreover, pretreatment with the ROCK inhibitor Y-27632 or GSK429286A drastically inhibited VEGF, CCL-18, or M2a induced migratory responses. These data suggest that the Rho-GTPases regulate M2a-mediated breast cancer cell invasion and potentially offer a novel approach for the treatment of metastatic breast cancer through potential prevention of progression. Citation Format: Andrew C. Little, Pragathi Pathanjeli, Zhifen Wu, Liwei Bao, Laura Goo, Joel A. Yates, Sofia D. Merajver. IL-4/IL-13 stimulated tumor-associated macrophages enhance breast cancer cell invasion through Rho-GTPase signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4518.

Abstract 69: Integrin α6β4 associates with plectin and vimentin in focal adhesions to enhance breast cancer cell invasion

Abstract Integrin α6β4 binds plectin to associate with intermediate filaments such as vimentin. While vimentin and integrin α6β4 are associated with the aggressiveness of triple negative breast cancer (TNBC), the biological importance of their association is not clear. Here, we utilized naturally occurring Epidermolysis Bullosa mutations in the integrin β4 subunit that are deficient in plectin binding to investigate the association between integrin α6β4 and vimentin. Using integrin β4-deficient BT549 cells, we generated cell lines that expressed integrin β4 wild type (β4-wt), plectin binding mutants (β4-R1225H or β4-R1281W), 1355-1662 deletion mutant (β4-Δ1355-1662; which retains plectin binding but deletes the signaling domain) or an empty control vector (EV). Migration assay and three-dimensional (3D) culture were performed to test whether integrin α6β4 signaling and its association with plectin contribute to the migratory and invasive phenotypes. Compared to EV cells, β4-wt increases cell migration and 3D invasive growth, but the β4-R1225H and β4-R1281W could not. CRISPR knockout of plectin also blocked β4-wt 3D cell growth. Utilizing total internal reflection fluorescence (TIRF) microscopy, we found that integrin β4-wt and β4-Δ1355-1662 were recruited to focal adhesions (FAs, indicated by paxillin co-staining) on laminin-1 plus fibronectin matrices, but not when plated on laminin-1 or fibronectin alone. Integrin β4-R1225H and β4-R1281W did not localize to FAs. Similarly, integrin β4-wt in plectin knockout cells could not aggregate in FAs. Furthermore, we observed that integrin αv and β1 colocalized with integrin β4 in FAs. Proximity ligation assay (PLA) indicated that the close interaction of integrin β1 and plectin. Interestingly, depletion of integrin β1 significantly reduced integrin β4 accumulation in FAs. Further immunostaining showed that integrin β4, plectin, and vimentin aggregated in FAs in the central area of the cell where FAs predominantly formed. Depletion of vimentin did not impact the recruitment of integrin β4 in FAs or cell proliferation, but significantly suppressed cell migration and 3D growth in β4-wt cells. Integrin β4-plectin-vimentin complexes were also found in MDA-MB-231 cells where they co-localized with paxillin and connected with stress fibers. In summary, our study demonstrates the essential roles of plectin binding and vimentin in promoting the migratory and invasive phenotypes by integrin α6β4 signaling in TNBC. Our study further highlights a novel function of plectin binding and integrin β1 in enhancing integrin β4 dynamics. Citation Format: Lei Qi, Teresa Knifley, Min Chen, Kathleen L. O’Connor. Integrin α6β4 associates with plectin and vimentin in focal adhesions to enhance breast cancer cell invasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 69.

Cleavage of the extracellular domain of junctional adhesion molecule-A is associated with resistance to anti-HER2 therapies in breast cancer settings

BackgroundJunctional adhesion molecule-A (JAM-A) is an adhesion molecule whose overexpression on breast tumor tissue has been associated with aggressive cancer phenotypes, including human epidermal growth factor receptor-2 (HER2)-positive disease. Since JAM-A has been described to regulate HER2 expression in breast cancer cells, we hypothesized that JAM-dependent stabilization of HER2 could participate in resistance to HER2-targeted therapies.MethodsUsing breast cancer cell line models resistant to anti-HER2 drugs, we investigated JAM-A expression and the effect of JAM-A silencing on biochemical/functional parameters. We also tested whether altered JAM-A expression/processing underpinned differences between drug-sensitive and -resistant cells and acted as a biomarker of patients who developed resistance to HER2-targeted therapies.ResultsSilencing JAM-A enhanced the anti-proliferative effects of anti-HER2 treatments in trastuzumab- and lapatinib-resistant breast cancer cells and further reduced HER2 protein expression and Akt phosphorylation in drug-treated cells. Increased epidermal growth factor receptor expression observed in drug-resistant models was normalized upon JAM-A silencing. JAM-A was highly expressed in all of a small cohort of HER2-positive patients whose disease recurred following anti-HER2 therapy. High JAM-A expression also correlated with metastatic disease at the time of diagnosis in another patient cohort resistant to trastuzumab therapy. Importantly, cleavage of JAM-A was increased in drug-resistant cell lines in conjunction with increased expression of ADAM-10 and -17 metalloproteases. Pharmacological inhibition or genetic silencing studies suggested a particular role for ADAM-10 in reducing JAM-A cleavage and partially re-sensitizing drug-resistant cells to the anti-proliferative effects of HER2-targeted drugs. Functionally, recombinant cleaved JAM-A enhanced breast cancer cell invasion in vitro and both invasion and proliferation in a semi-in vivo model. Finally, cleaved JAM-A was detectable in the serum of a small cohort of HER2-positive patients and correlated significantly with resistance to HER2-targeted therapy.ConclusionsCollectively, our data suggest a novel model whereby increased expression and cleavage of JAM-A drive tumorigenic behavior and act as a biomarker and potential therapeutic target for resistance to HER2-targeted therapies.

Abstract 469: Therapy-induced senescence associated secretory phenotype enhances breast cancer cell invasion and stemness via CXCR1/2-CXCR1/2 ligands axis

Abstract Various chemotherapeutic agents have been demonstrated to induce senescence of cancer cells in vitro and in vivo. This therapy-induced senescence (TIS) has been regard as a favorable therapeutic response, although it is not a cell death but a permanent cell cycle arrest. However, adverse aspects of TIS have been also suggested since senescence-associated secretory phenotype (SASP) enables to affect microenvironment of senescent cancer cells. Nonetheless, when senescent cancer cells are intermingled with non-senescent cells after chemotherapy, the effects of SASP from senescent cancer cell to non-senescent cell have not yet been fully elucidated. Therefore, TIS, confirmed by measuring senescence associated β-galactosidase activity and cell cycle arrest, was induced by the treatment with adriamycin and cisplatin in variable breast cancer cell lines in vitro. To evaluate the effects of SASP from senescent cancer cell to non-senescent cell, conditioned media (CM) from TIS of MCF7 (poorly-aggressive and non-invasive cell line) was treated in parent non-senescent MCF7 and their invasiveness and stemness were measured by invasion assay and mammosphere forming assay, respectively. In MCF7 treated with CM from TIS, invasiveness and mammosphere forming ability were significantly increased. To discover the mediators of the observed effects, cytokine array was performed by collecting CM from non-senescent control and therapy-induced senescent cells. In the secretome of TIS, CXCR2 ligands, including growth-related protein-α (CXCL1) and interleukin-8 (CXCL8) were focused on for further analysis. Increased mRNA of CXCR2 ligands (CXCL1, 2, 3 and CXCL8) in TIS and increased secretion of CXCL8 protein in CM of TIS were confirmed by real time PCR and ELISA, respectively. To investigate the contribution of CXCR1/2-CXCR1/2 ligands axis in enhanced invasion and stemness ability by CM of TIS, a CXCR1/2 specific inhibitor, SCH-527123, was applied. The pretreatment of SCH-527123 in the concentration without affecting cell proliferation and survival (25, 50μM), significantly inhibited the enhanced invasion and mammosphere forming ability by CM of TIS. The potential mechanisms of cancer cell invasion and stemness enhancement by CXCR1/2-CXCR1/2 ligands axis, are currently under investigated. In summary, SASP of TIS can be harmful by augmenting invasion and stemness of surrounding non-senescent cancer cell thorough the CXCR1/2-CXCR1/2 ligands axis and CXCR1/2 inhibitors can be used as therapeutic agents, by antagonizing the adverse effects of TIS. Citation Format: Yong Won Choi, Hyun-Young Cha, Tae Jun Park, Mi Sun Ahn, Hyun Woo Lee, Seong Hyun Jeong, Seok Yun Kang, Joon Seong Park, Jin-Hyuk Choi. Therapy-induced senescence associated secretory phenotype enhances breast cancer cell invasion and stemness via CXCR1/2-CXCR1/2 ligands axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 469.

Abstract 4010: MicroRNA regulator of NMI: implications for breast cancer

Abstract Recent investigations by our laboratory have demonstrated that NMI expression is down-regulated in patient breast tumors, especially those displaying invasive/metastatic features. In breast cancer and melanoma cell lines, restored expression of NMI suppresses tumor growth. Furthermore, NMI negatively impacts TGFβ-driven epithelial-mesenchymal-transition (EMT) and alsometastatic invasion of breast cancer. Thus the mechanisms that regulate NMI expression are of potential interest to understand the etiology of breast tumor progression, invasion, metastasis and to identify potentially novel therapeutic targets. MicroRNAs are critical regulators of gene expression. MicroRNA target prediction searches revealed that the NMI transcript could be targeted by the miR-29 family, a group of miRNAs with multiple roles in diverse cancer types. We hypothesized that miR-29 will negatively regulate NMI expression. Luciferase reporter assays using pMIR-REPORTTM confirmed the projected interaction of miR-29 in the seed region of the 3′ UTR of NMI. Manipulation of miR-29 levels in breast cancer cells by overexpression or silencing showed its inverse relationship with NMI expression. Invasive mesenchymal-like breast cancer cell lines showed elevated endogenous levels of miR-29 relative to tumorigenic/non-metastatic (epithelial like) breast cancer cell lines. Moreover, transient overexpression of miR-29 enhanced breast cancer cell invasion as measured by modified Boyden chamber assay and silencing miR-29 using anti-miRs decreased invasion. Investigations on the impact of miR-29 modulation on EMT revealed that increasing miR-29 levels in epithelial-like breast cancer cell lines caused 3D morphological changes indicative of invasive mesenchymal-like growth, while decreasing miR-29 levels from mesenchymal-like cell types using anti-miRs reversed the phenotype and the growth pattern resembled acinar structures. The significance of our observation was realized when we compared RNA isolated from patient derived breast cancer tumors and compared with RNA from matched adjacent normal breast specimens. Analysis using the McNemar's test showed a strong, inverse relationship between the expression of NMI and the miR-29. We contend that aberrant miR-29 expression may account for reduced NMI in some invasive breast cancers. Citation Format: Hawley C. Pruitt, Jack W. Rostas III, Brandon J. Metge, Daniel J. Devine, Sarah K. Bailey, Lalita A. Shevde, Rajeev Samant. MicroRNA regulator of NMI: implications for breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4010. doi:10.1158/1538-7445.AM2014-4010

Kindlin‐3 enhances breast cancer progression and metastasis by activating Twist‐mediated angiogenesis

The FERM domain containing protein Kindlin-3 has been recognized as a major regulator of integrin function in hematopoietic cells, but its role in neoplasia is totally unknown. We have examined the relationship between Kindlin-3 and breast cancer in mouse models and human tissues. Human breast tumors showed a ∼7-fold elevation in Kindlin-3 mRNA compared with nonneoplastic tissue by quantitative polymerase chain reaction. Kindlin-3 overexpression in a breast cancer cell line increased primary tumor growth and lung metastasis by 2.5- and 3-fold, respectively, when implanted into mice compared with cells expressing vector alone. Mechanistically, the Kindlin-3-overexpressing cells displayed a 2.2-fold increase in vascular endothelial growth factor (VEGF) secretion and enhanced β1 integrin activation. Increased VEGF secretion resulted from enhanced production of Twist, a transcription factor that promotes tumor angiogenesis. Knockdown of Twist diminished VEGF production, and knockdown of β1 integrins diminished Twist and VEGF production by Kindlin-3-overexpressing cells, while nontargeting small interfering RNA had no effect on expression of these gene products. Thus, Kindlin-3 influences breast cancer progression by influencing the crosstalk between β1 integrins and Twist to increase VEGF production. This signaling cascade enhances breast cancer cell invasion and tumor angiogenesis and metastasis.

The role of versican G3 domain in regulating breast cancer cell motility including effects on osteoblast cell growth and differentiation in vitro– evaluation towards understanding breast cancer cell bone metastasis

BackgroundVersican is detected in the interstitial tissues at the invasive margins of breast carcinoma, is predictive of relapse, and negatively impacts overall survival rates. The versican G3 domain is important in breast cancer cell growth, migration and bone metastasis. However, mechanistic studies evaluating versican G3 enhanced breast cancer bone metastasis are limited.MethodsA versican G3 construct was exogenously expressed in the 66c14 and the MC3T3-E1 cell line. Cells were observed through light microscopy and viability analyzed by Coulter Counter or determined with colorimetric proliferation assays. The Annexin V-FITC apoptosis detection kit was used to detect apoptotic activity. Modified Chemotactic Boyden chamber migration invasion assays were applied to observe tumor migration and invasion to bone stromal cells and MC3T3-E1 cells. Alkaline phosphatase (ALP) staining and ALP ELISA assays were performed to observe ALP activity in MC3T3-E1 cells.ResultsIn the four mouse breast cancer cell lines 67NR, 66c14, 4T07, and 4T1, 4T1 cells expressed higher levels of versican, and showed higher migration and invasion ability to MC3T3-E1 cells and primary bone stromal cells. 4T1 conditioned medium (CM) inhibited MC3T3-E1 cell growth, and even lead to apoptosis. Only 4T1 CM prevented MC3T3-E1 cell differentiation, noted by inhibition of alkaline phosphatase (ALP) activity. We exogenously expressed a versican G3 construct in a cell line that expresses low versican levels (66c14), and observed that the G3-expressing 66c14 cells showed enhanced cell migration and invasion to bone stromal and MC3T3-E1 cells. This observation was prevented by selective EGFR inhibitor AG1478, selective MEK inhibitor PD 98059, and selective AKT inhibitor Triciribine, but not by selective JNK inhibitor SP 600125. Versican G3 enhanced breast cancer cell invasion to bone stromal cells or osteoblast cells appears to occur through enhancing EGFR/ERK or AKT signaling. G3 expressing MC3T3-E1 cells showed inhibited cell growth and cell differentiation when cultured with TGF-β1 (1 ng/ml), and expressed enhanced cell apoptosis when cultured with TNF-α (2 ng/ml). Enhanced EGFR/JNK signaling appears to be responsible for G3 enhanced osteoblast apoptosis and inhibited osteoblast differentiation. Whereas repressed expression of GSK-3β (S9P) contributes to G3 inhibited osteoblast growth. Versican G3 functionality was dependent on its EGF-like motifs. Without the structure of EGF-like repeats, the G3 domain would not confer enhancement of tumor cell migration and invasion to bone with concordant inhibition of osteoblast differentiation and promotion of osteoblast apoptosis.ConclusionsVersican enhances breast cancer bone metastasis not only through enhancing tumor cell mobility, invasion, and survival in bone tissues, but also by inhibiting pre-osteoblast cell growth, differentiation, which supply favorable microenvironments for tumor metastasis.

Pdcd4 repression of lysyl oxidase inhibits hypoxia-induced breast cancer cell invasion

Metastasis to bone, liver and lungs is the primary cause of death in breast cancer patients. Our studies have revealed that the novel tumor suppressor Pdcd4 inhibits breast cancer cell migration and invasion in vitro. Loss of Pdcd4 in human nonmetastatic breast cancer cells increased the expression of lysyl oxidase (LOX) mRNA. LOX is a hypoxia-inducible amine oxidase, the activity of which enhances breast cancer cell invasion in vitro and in vivo. Specific inhibition of LOX activity by beta-aminopropionitrile or small interfering RNA decreased the invasiveness of T47D and MCF7 breast cancer cells attenuated for Pdcd4 function. Most significantly, loss of Pdcd4 augments hypoxia induction of LOX as well. Conversely, overexpression of Pdcd4 significantly reversed the hypoxia induction of LOX expression in T47D cells attenuated for Pdcd4. However, Pdcd4 did not affect hypoxia-inducible factor-1 (HIF-1) protein expression or HIF-1-responsive element-luciferase activity in response to hypoxia, suggesting that Pdcd4 regulation of LOX occurs through an HIF-independent mechanism. Nevertheless, the loss of Pdcd4 early in cancer progression may have an important role in the increased sensitivity of cancer cells to hypoxia through increased LOX activity and concomitant enhanced invasiveness.

Intrinsic genetic characteristics determine tumor-modifying capacity of fibroblasts: matrix metalloproteinase-3 5A/5A genotype enhances breast cancer cell invasion

BackgroundStromal fibroblasts can contribute to tumor invasion through the release of matrix metalloproteinases (MMPs). Population studies have suggested that single nucleotide polymorphisms (SNPs) in MMP genes influence levels of expression and may be associated with breast cancer risk and with disease progression. This study directly examined the impact of MMP SNP genotype on the ability of host fibroblasts to promote tumor cell invasion.MethodsPrimary breast fibroblasts were isolated from patients with (n = 13) or without (n = 19) breast cancer, and their ability to promote breast cancer cell invasion was measured in in vitro invasion assays. Fibroblast invasion-promoting capacity (IPC) was analyzed in relation to donor type (tumor or non-tumor patient), MMP-1, MMP-3, and MMP-9 SNP genotype and MMP activity using independent samples t test and analysis of variance. All statistical tests were two-sided.ResultsTumor-derived fibroblasts promoted higher levels of invasion than normal fibroblasts (p = 0.041). When IPC was related to genotype, higher levels of IPC were generated by tumor fibroblasts with the high-expressing MMP-3 5A/5A genotype compared with the 5A/6A and 6A/6A genotypes (p = 0.05 and 0.07, respectively), and this was associated with enhanced MMP-3 release. The functional importance of MMP-3 was demonstrated by enhanced invasion in the presence of recombinant MMP-3, whereas reduction occurred in the presence of a specific MMP-3 inhibitor. An inverse relationship was demonstrated between fibroblast IPC and the high-expressing MMP-1 genotype (p = 0.031), but no relationship was seen with MMP-9 SNP status. In contrast, normal fibroblasts showed no variation in IPC in relation to MMP genotype, with MMP-3 5A/5A fibroblasts exhibiting significantly lower levels of IPC than their tumor-derived counterparts (p = 0.04).ConclusionThis study has shown that tumor-derived fibroblasts exhibit higher levels of IPC than normal fibroblasts and that the MMP-3 5A/5A genotype contributes to this through enhanced MMP-3 release. Despite a high-expressing genotype, normal fibroblasts do not exhibit higher IPC or enhanced MMP release. This suggests that more complex changes occur in tumor-derived fibroblasts, enabling full expression of the MMP SNP genotype and these possibly are epigenetic in nature. The results do suggest that, in women with breast cancer, a high-expressing MMP-3 genotype may promote tumor progression more effectively.

TIP30/CC3 expression in breast carcinoma: relation to metastasis, clinicopathologic parameters, and P53 expression

Metastasis is the most frequent cause of death in patients with breast cancer. Tip30/CC3 gene is a putative metastasis suppressor gene, which was first identified by a differential display analysis of messenger RNA from the highly metastatic human variant small cell lung carcinoma (SCLC) versus less metastatic classic SCLC cell lines. The aim of this study was to analyze the relationship between expression of TIP30/CC3 and clinical prognosis in 87 patients with surgically removed breast carcinoma. Tumor tissues were stained immunohistochemically with anti-TIP30/CC3 antibody. We demonstrated that the expression of TIP30/CC3 was inversely associated with axillary lymph node metastasis (P = .0008) and vascular invasion (P = .0016). Expression of TIP30/CC3 was not correlated with tumor grade, estrogen, progesterone, and P53 expression. Inhibition of TIP30/CC3 expression by RNA-mediated interference greatly enhanced breast cancer cell invasion through the extracellular matrix, whereas overexpression of TIP30/CC3 by adenovirus vector suppressed invasion through the extracellular matrix. These data supported the theory that the expression of TIP30/CC3 had a suppressive function on tumor metastasis. In summary, the decrease in expression of TIP30/CC3 is related to metastasis and may represent a new prognosticator in breast carcinoma.

Coupling of RAFTK/Pyk2 kinase with c-Abl and their role in the migration of breast cancer cells

Mitogen-induced changes in the actin cytoskeleton are accompanied by changes in the tyrosine phosphorylation of several proteins in focal adhesions. In this study, we have investigated the role of RAFTK (also termed Pyk2/CAK-beta), a cytoplasmic tyrosine kinase related to focal adhesion kinase (FAK), in heregulin-mediated signal transduction in breast cancer cells. Stimulation of T47D cells with heregulin (HRG) induced the tyrosine phosphorylation of RAFTK and the formation of a multiprotein complex. Maximal phosphorylation of the proteins participating in this complex occurred within 2 h of HRG stimulation. Analyses of the members of the HRG-stimulated complex revealed that RAFTK associated with p190 RhoGAP (p190), RasGAP, c-Abl as well as with the focal adhesion molecules p130cas and paxillin. c-Abl was found to be associated with RAFTK through the region of RAFTK containing amino acids 419-1009. Site-directed mutagenesis of Y881 aa within the RAFTK sequence abolished the binding of RAFTK to c-Abl, indicating that the tyrosine residue 881 of RAFTK is the c-Abl binding site within the RAFTK molecule. Overexpression of wild-type RAFTK significantly enhanced breast cancer cell invasion, while overexpression of the mutants Tyr402 or Tyr881 of RAFTK inhibited this migration. Therefore, RAFTK serves as a mediator and an integration point between focal adhesion molecules in HRG-mediated signaling in T47D breast cancer cells.