Inhibits Breast Cancer Cell Invasion Research Articles

Suppression of OGT by microRNA24 reduces FOXA1 stability and prevents breast cancer cells invasion

O-GlcNAc transferase (OGT) catalyzes the addition of O-GlcNAc to certain serine or threonine residue on a wide variety of cytosolic and nuclear proteins and regulates cellular activities such as signaling and transcription. Although there are emerging evidences that OGT plays important roles in breast cancer metastasis, the underlying mechanism is not fully understood. In this study, we demonstrated that up-regulation of OGT correlates with breast cancer cells invasion. Over-expression of OGT stimulates cells invasion, while OGT silence exhibits the opposite effects. OGT is further identified as a target of microRNA24 (miR24). miR24 down-regulates OGT expression and subsequently suppresses cells invasion. Re-expression of OGT significantly rescues miR24-mediated invasion repression. Furthermore, our data showed that FOXA1 is subjected to O-GlcNAcylation, which instabilizes FOXA1 protein and promotes breast cancer cells invasion. In conclusion, our results demonstrated that miR24 inhibits breast cancer cells invasion by targeting OGT and reducing FOXA1 stability. These results also indicated that OGT might be a potential target for the diagnosis and therapy of breast cancer metastasis.

Astragaloside IV inhibits breast cancer cell invasion by suppressing Vav3 mediated Rac1/MAPK signaling

BackgroundAstragaloside IV (AS-IV), the major active triterpenoid in Radix Astragali, has shown anti-tumorigenic properties in certain cancers; however, its role in breast cancer remains unclear. The present study investigated the effects of AS-IV on breast cancer in vitro and in vivo and examined the underlying mechanisms. MethodsThe effects of AS-IV on MDA-MB-231 cell proliferation, migration, invasion and metastasis were investigated by MTT and Transwell assays, and western blotting. In addition, an orthotopic mouse tumor model was established for in vivo experiments. ResultsAS-IV inhibited the viability and invasive potential of MDA-MB-231 breast cancer cells, suppressed the activation of the mitogen activated protein kinase (MAPK) family members ERK1/2 and JNK, and downregulated matrix metalloproteases (MMP)-2 and -9. The effects of AS-IV were mediated by the downregulation of Vav3, a guanine nucleotide exchange factor, leading to decreased levels of activated Rac1, a Rho family GTPase. Vav3 overexpression promoted cell proliferation and invasion in vitro, whereas Vav3 silencing had the opposite effects. AS-IV suppressed orthotopic breast tumor growth and metastasis to the lungs, whereas ectopic expression of Vav3 reversed the inhibitory effect of AS-IV on cell viability, invasiveness, MAPK signaling and MMP expression. ConclusionThe present results provide a mechanistic explanation for the antitumor effects of AS-IV and suggest its potential in the treatment of metastatic breast cancer.

The role of PAQR3 gene promoter hypermethylation in breast cancer and prognosis.

PAQR3 is a tumor suppressor in breast cancer and its expression regulation mechanism has not been well elucidated. In this study, we found that PAQR3 expression was downregulated in breast cancer tissues, and the downregulation of PAQR3 expression was found to be significantly associated with aberrant methylation of the gene promoter. Methylation‑specific PCR showed that hypermethylation of the PAQR3 gene was observed in 71.8% of the breast cancers, whereas it was found in only 28.2% of the corresponding non‑tumor tissues. Moreover, we found that the PAQR3 promoter methylation status was related to lymph node metastasis (P=0.01). In addition, overexpression of PAQR3 inhibited breast cancer cell invasion and growth. Furthermore, PAQR3 expression was restored in MCF‑7 cells after treatment with the demethylating agent, 5-aza-2'-deoxycytidine, and the effect of demethylation induced invasion and proliferation suppression of MCF‑7 cells. Collectively, our results suggested that the aberrant methylation of PAQR3 underlies its downregulation in breast cancer and our data indicated that epigenetic silencing of PAQR3 gene expression by promoter hypermethylation may play an important role in breast cancer.

Class II phosphoinositide 3-kinase C2β regulates a novel signaling pathway involved in breast cancer progression.

It is now well established that the enzymes phosphoinositide 3-kinases (PI3Ks) have a key role in the development and progression of many cancer types and indeed PI3Ks inhibitors are currently being tested in clinical trials. Although eight distinct PI3K isoforms exist, grouped into three classes, most of the evidence currently available are focused on one specific isoform with very little known about the potential role of the other members of this family in cancer. Here we demonstrate that the class II enzyme PI3K-C2β is overexpressed in several human breast cancer cell lines and in human breast cancer specimens. Our data indicate that PI3K-C2β regulates breast cancer cell growth in vitro and in vivo and that PI3K-C2β expression in breast tissues is correlated with the proliferative status of the tumor. Specifically we show that downregulation of PI3K-C2β in breast cancer cell lines reduces colony formation, induces cell cycle arrest and inhibits tumor growth, in particular in an estrogen-dependent in vivo xenograft. Investigation of the mechanism of the PI3K-C2β-dependent regulation of cell cycle progression and cell growth revealed that PI3K-C2β regulates cyclin B1 protein levels through modulation of microRNA miR-449a levels. Our data further demonstrate that downregulation of PI3K-C2β inhibits breast cancer cell invasion in vitro and breast cancer metastasis in vivo. Consistent with this, PI3K-C2β is highly expressed in lymph-nodes metastases compared to matching primary tumors. These data demonstrate that PI3K-C2β plays a pivotal role in breast cancer progression and in metastasis development. Our data indicate that PI3K-C2β may represent a key molecular switch that regulates a rate-limiting step in breast tumor progression and therefore it may be targeted to limit breast cancer spread.

Abstract A58: Expression and function of endothelin converting enzyme 1 and endothelin receptors in breast cancer invasion

Abstract The endothelin axis, comprised of the active peptides endothelin 1-3 (ET1-3), the endothelin A receptor (ETAR) and endothelin B receptor (ETBR), and endothelin converting enzyme 1 (ECE1) has been studied in numerous cancers. In clinical samples of breast cancer, increased levels of ET1, ECE1, and the endothelin receptors have been reported, and several studies correlate expression of these proteins with poor prognosis. The endothelin pathway is known to induce mitogen activated protein kinase activation, leading to increased survival, proliferation, and migration, but the precise role of ECE1 and the endothelin receptors in breast cancer invasion is not fully understood. We hypothesized that the endothelin axis is instrumental in modulating breast cancer cell invasion. To initially confirm that the endothelin axis regulates breast cancer cell invasion, we measured MDA-MB-231 breast cancer cell invasion using an in vitro assay in the presence of an ECE1 inhibitor, CGS 35066, and found that abrogating ECE1 decreases breast cancer invasion. Next, we measured expression of ECE1 mRNA and protein using RT-PCR and Western blots in normal human mammary epithelial cells (HMECs), low-invading MCF-7 breast cancer cells, and highly invasive MDA-MB-231 breast cancer cells. We found that the major ECE1 isoform, ECE-1c, was most highly expressed on MCF-7 cells and that HMECs expressed more of the intracellular ECE1 isoform, ECE-1b, than either cancer cell line. Western blot analysis confirmed these results, as total ECE1 protein expression was highest in the MCF-7 cells. While multiple studies have been published on the expression of the endothelin receptors ETAR and ETBR in clinical breast cancer samples, less is known about the specific expression and function of these receptors in these breast cancer cell lines. Western blot analysis demonstrated notable up-regulation of ETAR expression in the MCF-7 and MDA-MB-231 cells compared to the HMECs, which is consistent with clinical findings. Interestingly, ETBR expression was expressed in HMECs but its expression was low or negative in both breast cancer cell lines. Previous studies have demonstrated that knockdown of ETAR inhibits breast cancer cell invasion, but whether ETBR functions similarly in breast cancer is unknown. To determine if ETBR might be regulating invasion in mammary cells, we transfected MCF7 cells with ETBR-specific siRNA and found that knocking down the gene encoding for ETBR (EDNRB) resulted in significantly increased cell invasion. This result suggests that while ETAR positively regulates breast cancer cell invasion, as reported in other studies, ETBR may be negatively regulating invasion through the endothelin axis. Together, our findings support an important role for the endothelin axis in breast cancer invasion, and specifically implicate ETAR and ETBR as performing complimentary and opposing roles in the regulation of breast cancer cell invasion. Citation Format: Mary Elizabeth Belles, Meena Halaka, Jessica M. Do, Parth Majmudar, Reem Sidani, Hannah Stephen, Molly Watson, Rebecca E. Conway. Expression and function of endothelin converting enzyme 1 and endothelin receptors in breast cancer invasion. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr A58.

Abstract 4125: SSA, a novel sulindac derivative, inhibits breast cancer cell invasion and migration

Abstract Nonsteroidal anti-inflammatory drugs (NSAIDs), such as sulindac, have been reported for striking chemopreventive activity in various types of human cancer, including breast cancer. However, few studies have reported that sulindac is able to prevent tumor metastasis. In this study, we aim to study anti-metastatic activity of sulindac in breast cancer and explore the mechanistic basis responsible for this activity, which we hypothesize may involve a cyclooxygenase (COX) independent mechanism. Numerous studies have reported that the anticancer properties of sulindac might involve, at least partially, a non-COX mediated mechanism, which provides an insight into development of safer and more efficacious new derivatives. We have previously described a chemical derivative of sulindac, referred to as sulindac sulfide amide (SSA), which lacks inhibitory effect on COX-1 or -2, yet shows greater potency to inhibit tumor cell growth compared with sulindac sulfide (SS). Our results showed that SSA treatment at a sub-cytotoxic concentration (4μM) for 36 h significantly inhibits both migration and invasion of highly aggressive MDA-MB-231, BT-20 and SK-BR-3 breast tumor cells. When treating non-invasive breast MCF-7 cells with TGF-β1 to induce their motility, we found that SSA could significantly counteract the induced motility of these cells. These results indicate that SSA can suppress breast tumor cell invasion by modulation of TGF-β1 signaling. We further studied Smad-2/3 that are important downstream components in the TGF-β1 signaling pathway and found that SSA could inhibit Smad-2/3 phosphorylation and reduce their translocation to the nucleus. In addition, Smad-2/3 knockdown could mimic the anti-invasive effect of SSA in MDA-MB-231 cells, regardless of the presence of TGF-β1. In summary, we demonstrate that the non-COX inhibitory derivative, SSA can suppress breast cancer cell invasion and migration. These observations suggest that inhibition of TGF-β1/Smad signaling is responsible for the inhibitory effect of SSA on breast tumor cell invasion and migration. Citation Format: Bin Yi, Xingling Feng, Ruixia Ma, Xiaoguo Zhang, Hong Chang, Hongyou Zhao, Ziping Liang, Xi Chen, Xiuhua Hu, Gary Piazza, Yaguang Xi. SSA, a novel sulindac derivative, inhibits breast cancer cell invasion and migration. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4125. doi:10.1158/1538-7445.AM2015-4125

Abstract 1277: Tumor-specific human monoclonal antibodies isolated from cancer patients that bind antigens expressed on the outer plasma membrane of cancer cells

Abstract Introduction: Cancer cells express novel antigens that reflect their transformed state and may engender an antibody response. We hypothesize that some of these auto-antibodies detect neo-antigens that are shared by diverse tumor types and that a subset of these are expressed on the outer plasma membrane (PM) of cancer cells, but not normal cells. Here, we describe two human mAbs, isolated from lymph node B-cells of breast cancer patients, that bind antigens expressed only on the surface of cancer cells. Methods: We have optimized a hybridoma method for cloning human IgG monoclonal antibodies (mAbs) by screening for those that bind to live, heterologous cancer cell lines. We use whole cell immunofluorescence binding assays with human cancer cell lines, detecting cell-reactive human IgG with the Operetta. We use B-cells from lymph nodes obtained at surgery from stage I, ER+PR+ breast cancer patients and Stage I or II lung cancer patients, as well as peripheral blood B-cells from lung cancer patients responsive to PD-1 inhibitors. We used cDNA library expression methods to identify the tumor antigens and characterized the tumor-specific activities of two mAbs using immunohistochemistry (IHC), gene transfection, flow cytometry, immunoblotting, and invasion assays. Results: Two of the mAbs isolated from lymph nodes of patients with breast cancer bind to antigens that are only expressed on the outer PM of cancer cells. The antigen recognized by mAb 9H2 is known to be expressed on the outer PM of metastatic cells, while the antigen recognized by mAb 2B9 is a cytoplasmic protein not previously recognized to exist on the outer PM. IHC demonstrates that the 9H2 antigen is expressed only rarely on normal cells, but is commonly on breast and colon cancers (3 of 4 samples tested for each tumor type). Binding was also seen on 2 of 4 small cell lung cancers samples and 1 of 3 pancreatic cancers. The existence of the 2B9 antigen on the outer PM was confirmed by study of 293T cells transiently transfected with MYC-tagged antigen expression constructs and analyzed by flow cytometry with the mAb 2B9 and an anti-myc mAb. Treatment of MDA-MB-231 cells with the mAb 2B9 substantially reduced invasion in the transwell migration assay. An additional panel of 12 mAbs exhibited internalizing activity and is being evaluated for efficacy as antibody-drug conjugates Conclusion: Our panel of mAbs from cancer patients supports the hypothesis that patients with malignancies make antibodies that bind novel cancer-specific antigens. Two mAbs bind antigens expressed only on the surface of malignant cells; one has not previously been detected on the outer PM. The ability of mAb 2B9 to inhibit breast cancer cell invasion suggests that the anti-tumor immune response may be functional. Studying the anti-cancer antibody repertoire may identify new targets for mAb-based cancer diagnostics and therapeutics. Citation Format: Baron Heimbach, Cezary Swider, Huiwu Zhao, Paul Simon, R. Katherine Alpaugh, Michael Walker, David Krag, David Knight, Tung Chan, Hossein Borghaei, Scott Dessain. Tumor-specific human monoclonal antibodies isolated from cancer patients that bind antigens expressed on the outer plasma membrane of cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1277. doi:10.1158/1538-7445.AM2015-1277

Sinomenine inhibits breast cancer cell invasion and migration by suppressing NF-κB activation mediated by IL-4/miR-324-5p/CUEDC2 axis

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a vital transcription factor that regulates multiple important biological processes, including the epithelial–mesenchymal transition (EMT) and metastasis of breast cancer. Sinomenine is an isoquinoline well known for its remarkable curative effect on rheumatic and arthritic diseases and can induce apoptosis of several cancer cell types. Recently, sinomenine was reported as a tumor suppressor via inhibiting cell proliferation and inducing apoptosis. However, the role and mechanism of sinomenine in invasion and metastasis of breast cancer are largely unknown. Here, we report that sinomenine suppressed the invasion and migration of MDA-MB-231 and 4T1 breast cancer cells in a dose-dependent manner. We detected binding of NF-κB to the inhibitor of NF-κB (IκB) after the MDA-MB-231 cells were treated with 0.25, 0.5, and 1 mM sinomenine. Co-IP analysis revealed that sinomenine enhanced the binding of NF-κB and IκB in a dose-dependent manner, suggesting that sinomenine had an effect on inactivation of NF-κB. Western blotting and ELISA approaches indicated that the suppression effect was closely associated with the phosphorylation of IκB kinase (IKK) and its negative regulator CUEDC2. Sinomenine treatment decreased miR-324-5p expression, thus increased the level of its target gene CUEDC2, and then blocked the phosphorylation of IKK through altering the upstream axis. Finally, transfection of a miR-324-5p mimic inhibited the suppression of invasion and metastasis of MDA-MB-231 and 4T1 cell by sinomenine, providing evidence that sinomenine treatment suppressed breast cancer cell invasion and metastasis via regulation of the IL4/miR-324-5p/CUEDC2 axis. Our findings reveal a novel mechanism by which sinomenine suppresses cancer cell invasion and metastasis, i.e., blocking NF-κB activation.

MicroRNA-335 inhibits breast cancer cell invasion by targeting human epidermal growth factor receptor 3

Objective In this study, we aim to detect microRNA(miR)- 335 function in cell invasion. Methods In vitro, we respectively inhibited or over- expressed miR- 335 in MCF10A and MCF7 to detect the change of cell invasion by transwell invasion assay.The bioinformatics was used to predict the target of miR- 335 and later it was investigated by luciferase reporter assay.Through the single- tranfection or cotransfection of miR- 335 inhibitor or human epidermal growth factor receptor 3(ERBB3)siRNA, we detected whether miR- 335 affects invasion by targeting ERBB3.At last, through realtime quantative polymerase chain reaction, we detected the expression level of miR- 335 in primary breast cancer specimen. Results Inhibition of miR- 335 in MCF10A reduced the ability of cell invasion.Invasion cell numbers enhanced from 51 of control group to 67 of exprimental group.The P value is lower than 0.05.Over- expression of miR- 335 enhanced the ability of cell invasion.Invasion cell numbers decreased from 51 of control group to 43 of exprimental group(P<0.05).miR- 335 could target the 3'untranslated regions of ERBB3 mRNA and inhibited its mRNA and protein level(P<0.05).Inhibition of ERBB3 could resuce the change of cell invasion that miR-335 inhibitors contributed to(P< 0.05).miR- 335 showed lower expression level in primary breast cancer specimen compared to adjacent tissues(P<0.01). Conclusion miR-335 showed lower expression in primary breast cancer and affected breast cancer cell invasion by targeting ERBB3. Key words: Breast cancer; MicroRNA-335; Human epidermal growth factor receptor 3; Invasion

Abstract P2-06-08: SIRT1 inhibitors significantly reduce cancer stem cells and block epithelial mesenchymal transformation in breast cancer cells

Abstract Breast cancer stem cells are contribute to distance metastasis, breast cancer recurrence and drug resistance. SIRT1, a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylase, play significant role in DNA repair, cell survival, stem cells and epigenetic modification. SIRT1 has been related to cancer stem cells in chronic myelogenous leukemia. In this study, we investigate the role of SIRT1 in breast cancer stem cells. SIRT1 inhibitors cambinol and Ex527 are used for treatment in several breast cancer cell lines, including T47D, TB549, MDA-MB-231 and MDA-MB-468. Stem cell markers, SOX-2 and Nanog, are significantly decreased in SIRT1 inhibitor treated cancer cells by qRT-PCR and western blot in T47D cell line. The ALDH positive cells in MDA-MB-231 cell line are significant reduced from 29% to 3.2% with Adeflour assay, and the CD44 expression is significantly reduced in CD44/CD24 flow cytometry analysis. Using qRT-PCR, SIRT1 inhibitors significantly down regulate vimentin (-3.7 folds), N-cadherin and smooth muscle actin (-2.7 folds) and up regulate the gene of E-cadherin, indicating SIRT1 inhibitors can block the epithelial mesenchymal transformation (EMT) of breast cancer. SIRT1 inhibitors can significantly (40-50%) block the cancer cell invasion and migration in several triple negative breast cancer cell lines. SIRT1 inhibitors can inhibit cell proliferation on all tested breast cancer cell lines, and can induce significant cell apoptosis in T47D cells. In xenograft tumor study, SIRT1 inhibitor cambinol can significantly reduce tumor growth and inhibit tumor metastasis. The molecular mechanism of SIRT1 inhibitors in blocking EMT and reducing cancer stem cells is likely associated with blocking the Wnt pathway. Several down stream target genes of Wnt pathway, such as cyclin D1, c-Myc and c-Jun, are significantly down regulated after using SIRT1 inhibitor cambinol, and the changes are more significant in TGF-beta stimulated cancer cells. Beta-catenin is significantly reduced including the active beta-catenin, and the decreasing beta-catenin protein may be related to the decreased Dvl proteins. In summary, our study demonstrated that SIRT1 inhibitors can reduce breast cancer stem cell population in several cancer cell lines, block epithelial mesenchymal transformation, and inhibit breast cancer cell invasion and metastasis. SIRT1 inhibitors appear to inhibit Wnt pathway in cancer cells to block EMT and affect cancer stem cells. Citation Format: Songlin Zhang, Min Li, Baoxiang Guan, Robert Brown. SIRT1 inhibitors significantly reduce cancer stem cells and block epithelial mesenchymal transformation in breast cancer cells [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-06-08.

Stat3 orchestrates interaction between endothelial and tumor cells and inhibition of Stat3 suppresses brain metastasis of breast cancer cells.

Brain metastasis is a major cause of morbidity and mortality in patients with breast cancer. Our previous studies indicated that Stat3 plays an important role in brain metastasis. Here, we present evidence that Stat3 functions at the level of the microenvironment of brain metastases. Stat3 controlled constitutive and inducible VEGFR2 expression in tumor-associated brain endothelial cells. Furthermore, inhibition of Stat3 by WP1066 decreased the incidence of brain metastases and increased survival in a preclinical model of breast cancer brain metastasis. WP1066 inhibited Stat3 activation in tumor-associated endothelial cells, reducing their infiltration and angiogenesis. WP1066 also inhibited breast cancer cell invasion. Our results indicate that WP1066 can inhibit tumor angiogenesis and brain metastasis mediated by Stat3 in endothelial and tumor cells.

CERS2 suppresses tumor cell invasion and is associated with decreased V-ATPase and MMP-2/MMP-9 activities in breast cancer.

Ceramide synthase 2 (CERS2) is the gene identified from a human liver cDNA library in 2001. Our previous studies have shown higher expression of CERS2 in the breast cancer patients was associated with fewer lymph node metastases. However, the molecular mechanism of CERS2 involved is unknown. Here, we found CERS2 was heterogeneously expressed in various breast cancer cells. The mRNA and protein expression levels of CERS2 in MCF7 cells, which are poorly invasive breast cancer cells, were obviously higher than that in the highly invasive cells MDA-MB-231. Results showed overexpression of CERS2 in MDA-MB-231 cells could significantly inhibit the migration and invasion ability, whereas CERS2 knockdown in MCF7 cells could significantly increase the migration and invasion ability. Overexpression of CERS2 in MDA-MB-231 cells significantly reduced the V-ATPase activity, increased the extracellular pH and decreased the pH-dependent activity of MMP-2 and MMP-9 matrix metalloproteinases (MMPs). CERS2 knockdown in MCF7 cells significantly increased the V-ATPase activity, decreased the extracellular pH and increased the activity of MMP-2 and MMP-9. Taken together, CERS2 can significantly inhibit breast cancer cell invasion and is associated with the decrease of the V-ATPase activity and extracellular hydrogen ion concentration, and in turn the activation of secreted MMP-2/MMP-9 and degradation of extracellular matrix (ECM), which ultimately suppressed tumor's invasion. Thus, CERS2 may represent a novel target for selectively disrupting V-ATPase activity and the invasive potential of cancer cells.

Codonolactone, a sesquiterpene lactone isolated from Chloranthus henryi Hemsl, inhibits breast cancer cell invasion, migration and metastasis by downregulating the transcriptional activity of Runx2.

Metastasis is the most insidious aspect of breast cancer, but effective strategies to control this malignant process are still lacking. In previous studies, we screened over 200 extracts from plants of genus Chloranthaceae by bioactivity-guided fractionation, and found that Codonolactone (CLT) exhibited potential antimetastatic properties in breast cancer cells. This sesquiterpene lactone was isolated from Chloranthus henryi Hemsl, and is also found in other medical herbs, such as Codonopsis pilosula, Atractylodes macrocephala Koidz and others. Here, we report that CLT inhibited the ability of invasion and migration in metastatic breast cancer cells. Furthermore, CLT exhibited significant suppression on formation of lung metastatic foci of breast cancer in vivo. We next investigated the mechanism of CLT-induced metastasis inhibitory effects in breast cancer cells. A significant inhibition on activity and expression of MMP-9 and MMP-13 was observed. Moreover, data from western blotting, Runx2 transcription factor assay and chromatin immunoprecipitation assay showed that binding ability of Runx2 to sequences of the mmp-13 promoter was inhibited by CLT. Collectively, these findings suggested that the antimetastatic properties of CLT in breast cancer were due to the inhibition of MMPs, which might be associated with a downregulation of Runx2 transcriptional activity.

LRP1-dependent pepsin clearance induced by 2′-hydroxycinnamaldehyde attenuates breast cancer cell invasion

2′-Hydroxycinnamaldehyde inhibits breast cancer cell invasion. This study examined whether 2′-hydroxycinnamaldehyde, acting as a Michael acceptor, interferes with the ligand binding of low-density lipoprotein receptor-related protein 1 to mediate breast cancer cell invasion. Low-density lipoprotein receptor-related protein 1, one of the direct molecular targets of 2′-hydroxycinnamaldehyde, is a multifunctional endocytic receptor. Changes in the thiol oxidation status of cell surface receptor proteins may function as a molecular switch, influencing ligand(s) binding. The oxidation status of extracellular cysteine thiol groups in MCF-7 and MDA-MB-231 cells was examined using a fluorescence-activated cell sorter with thiol-specific fluorescent probes; Matrigel invasion and wound-healing assays were performed to determine the effects of 2′-hydroxycinnamaldehyde on in vitro cell migration. The molecular mechanisms by which 2′-hydroxycinnamaldehyde acts were evaluated by transient knockdown using siRNA or inhibition of low-density lipoprotein receptor-related protein 1 by receptor-associated protein treatment. 2′-Hydroxycinnamaldehyde increased α-2-macroglobulin binding to low-density lipoprotein receptor-related protein 1, which was alleviated by pretreatment of cells with N-acetylcystein. 2′-Hydroxycinnamaldehyde decreased the extracellular pepsin concentration significantly in a low-density lipoprotein receptor-related protein 1- and α-2-macroglobulin-dependent manner. The anti-invasive effect of 2′-hydroxycinnamaldehyde was mitigated with receptor-associated protein pretreatment, suggesting that low-density lipoprotein receptor-related protein 1 is essential for the effects of 2′-hydroxycinnamaldehyde. From these data, we suggest that 2′-hydroxycinnamaldehyde increases the cysteine thiol oxidation status of low-density lipoprotein receptor-related protein 1 extracellular domains, which results in α-2-macroglobulin ligand binding stimulation. Therefore, pepsin clearance in a low-density lipoprotein receptor-related protein 1-α-2-macroglobulin-dependent manner might be an important molecular mechanism in 2′-hydroxycinnamaldehyde exerting its anti-invasive action on breast cancer cells. Furthermore, our data may provide an opportunity to promote the importance of the thiol oxidation status of cell surface receptor proteins for regulating cellular signaling pathways that are important in cancer progression.

Relationship between moesin expression and breast cancer metastasis

Objective To explore the internal relationship between moesin expression and breast cancer metastasis. Methods Immunohistochemistry(IHC),RT-PCR and Western blot were`used to identify moesin expression in breast cancer tissue samples and a series of human breast cancer cell lines with different metastatic potentials.RNAi technique combined with invasion and motility assay in vitro were also used to reveal the interrelationship between moesin deficiency and invasion and motility ability of breast cancer cells.Results IHC analysis showed that moesin were mainly distributed on the cell membrane and cytoplasm.Its expression was higher in metastatic breast cancer tissue samples than in non-metastatic ones(P=0.001,χ2=17.536).Western blot results revealed positive correlation between moesin expression and metastatic potential of breast cancer cells.The results of Transwell experiment displayed that moesin expression silencing remarkably inhibited invasion and motility ability of breast cancer cells,especially the cells with high metastatic potential.After moesin expression,the levels of MTDH mRNA and nm-23mRNA in breast cancer cells(P0.05)significantly decreased,while vimentin expression increased,and the expressions of E-cadherin and MMP-9decreased. Conclusions Moesin over-expression presents a positive correlation to breast cancer metastatic potential.Moesin may participate in the process of invasion and metastasis of breast cancer cells through influencing MTDH and nm-23,enhancing epithelial mesenchymal transition and increasing MMP-9secretion.

Runx2 induces bone osteolysis by transcriptional suppression of TSSC1

Advanced breast cancers frequently metastasize to bone, resulting in osteolytic lesions, however, the underlying mechanisms are poorly understood. Runx2, a bone-specific transcriptional factor, is abnormally expressed in highly metastatic breast cancer cells. Here, we found that TSSC1 inhibits breast cancer cell invasion. Subsequently, TSSC1 is confirmed as a target of Runx2 and is negatively regulated by Runx2. Furthermore, overexpression of Runx2 induces bone osteolysis in a TSSC1-dependent manner. Our results may provide a strategy for the treatment of breast cancer and the prevention of skeletal metastasis.

Exosome-Bound WD Repeat Protein Monad Inhibits Breast Cancer Cell Invasion by Degrading Amphiregulin mRNA

Increased stabilization of mRNA coding for key cancer genes can contribute to invasiveness. This is achieved by down-regulation of exosome cofactors, which bind to 3'-UTR in cancer-related genes. Here, we identified amphiregulin, an EGFR ligand, as a target of WD repeat protein Monad, a component of R2TP/prefoldin-like complex, in MDA-MB-231 breast cancer cells. Monad specifically interacted with both the 3'-UTR of amphiregulin mRNA and the RNA degrading exosome, and enhanced decay of amphiregulin transcripts. Knockdown of Monad increased invasion and this effect was abolished with anti-amphiregulin neutralizing antibody. These results suggest that Monad could prevent amphiregulin-mediated invasion by degrading amphiregulin mRNA.

Inhibition of angiogenesis and invasion by DMBT is mediated by downregulation of VEGF and MMP-9 through Akt pathway in MDA-MB-231 breast cancer cells

Invasion, either directly or via metastasis formation, is the main cause of death in cancer patients, development of efficient anti-invasive agents is an important research challenge. In order to obtain more potent inhibitors, a series of brartemicin analogs were synthesized and evaluated for their inhibitory activity against invasion. Among the synthetic analogs tested, DMBT, 6,6'-bis (2,3-dimethoxybenzoyl)-a,a-D-trehalose, was found to be the most potent anti-invasive agent. But the effects of DMBT on breast cancer cells were not known. In this study, the effects of DMBT on invasion and metastasis in MDA-MB-231 cells were investigated. MTT assay showed that no obvious inhibitory or cytotoxic effect of DMBT was found. DMBT could inhibit invasion, migration and tube formation of HUVECs. Gelatin zymography showed that DMBT inhibited secretion and activity of MMP-9. Western blotting demonstrated that DMBT effectively suppressed the expression of VEGF, p-VEGFR-2, p-EGFR, and p-Akt. These results suggested that DMBT could inhibit invasion and angiogenesis by downregulation of VEGF and MMP-9, resulting from the inhibition of Akt pathway. DMBT might be a promising lead molecule for the anti-metastasis and serve as a therapeutic agent to inhibit breast cancer cell invasion and metastasis.

Histone Demethylase KDM6B Promotes Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is a critical event that occurs in embryonic development, tissue repair control, organ fibrosis, and carcinoma invasion and metastasis. Although significant progress has been made in understanding the molecular regulation of EMT, little is known about how chromatin is modified in EMT. Chromatin modifications through histone acetylation and methylation determine the precise control of gene expression. Recently, histone demethylases were found to play important roles in gene expression through demethylating mono-, di-, or trimethylated lysines. KDM6B (also known as JMJD3) is a histone demethylase that might activate gene expression by removing repressive histone H3 lysine 27 trimethylation marks from chromatin. Here we report that KDM6B played a permissive role in TGF-β-induced EMT in mammary epithelial cells by stimulating SNAI1 expression. KDM6B was induced by TGF-β, and the knockdown of KDM6B inhibited EMT induced by TGF-β. Conversely, overexpression of KDM6B induced the expression of mesenchymal genes and promoted EMT. Chromatin immunoprecipitation (ChIP) assays revealed that KDM6B promoted SNAI1 expression by removing histone H3 lysine trimethylation marks. Consistently, our analysis of the Oncomine database found that KDM6B expression was significantly increased in invasive breast carcinoma compared with normal breast tissues. The knockdown of KDM6B significantly inhibited breast cancer cell invasion. Collectively, our study uncovers a novel epigenetic mechanism regulating EMT and tumor cell invasion, and has important implication in targeting cancer metastasis.

Gonadotropin-releasing hormone receptor activates GTPase RhoA and inhibits cell invasion in the breast cancer cell line MDA-MB-231

BackgroundGonadotropin-releasing hormone (GnRH) and its receptor (GnRHR) are both expressed by a number of malignant tumors, including those of the breast. In the latter, both behave as potent inhibitors of invasion. Nevertheless, the signaling pathways whereby the activated GnRH/GnRHR system exerts this effect have not been clearly established. In this study, we provide experimental evidence that describes components of the mechanism(s) whereby GnRH inhibits breast cancer cell invasion.MethodsActin polymerization and substrate adhesion was measured in the highly invasive cell line, MDA-MB-231 transiently expressing the wild-type or mutant DesK191 GnRHR by fluorometry, flow cytometric analysis, and confocal microscopy, in the absence or presence of GnRH agonist. The effect of RhoA-GTP on stress fiber formation and focal adhesion assembly was measured in MDA-MB-231 cells co-expressing the GnRHRs and the GAP domain of human p190Rho GAP-A or the dominant negative mutant GAP-Y1284D. Cell invasion was determined by the transwell migration assay.ResultsAgonist-stimulated activation of the wild-type GnRHR and the highly plasma membrane expressed mutant GnRHR-DesK191 transiently transfected to MDA-MB-231 cells, favored F-actin polymerization and substrate adhesion. Confocal imaging allowed detection of an association between F-actin levels and the increase in stress fibers promoted by exposure to GnRH. Pull-down assays showed that the effects observed on actin cytoskeleton resulted from GnRH-stimulated activation of RhoA GTPase. Activation of this small G protein favored the marked increase in both cell adhesion to Collagen-I and number of focal adhesion complexes leading to inhibition of the invasion capacity of MDA-MB-231 cells as disclosed by assays in Transwell Chambers.ConclusionsWe here show that GnRH inhibits invasion of highly invasive breast cancer-derived MDA-MB-231 cells. This effect is mediated through an increase in substrate adhesion promoted by activation of RhoA GTPase and formation of stress fibers and focal adhesions. These observations offer new insights into the molecular mechanisms whereby activation of overexpressed GnRHRs affects cell invasion potential of this malignant cell line, and provide opportunities for designing mechanism-based adjuvant therapies for breast cancer.