Inhibits Breast Cancer Cell Metastasis Research Articles

Nuclear import of PTPN18 inhibits breast cancer metastasis mediated by MVP and importin β2

Distant metastasis is the primary cause of breast cancer-associated death. The existing information, such as the precise molecular mechanisms and effective therapeutic strategies targeting metastasis, is insufficient to combat breast cancer. This study demonstrates that the protein tyrosine phosphatase PTPN18 is downregulated in metastatic breast cancer tissues and is associated with better metastasis-free survival. Ectopic expression of PTPN18 inhibits breast cancer cell metastasis. PTPN18 is translocated from the cytoplasm to the nucleus by MVP and importin β2 in breast cancer. Then, nuclear PTPN18 dephosphorylates ETS1 and promotes its degradation. Moreover, nuclear PTPN18 but not cytoplasmic PTPN18 suppresses transforming growth factor-β signaling and epithelial-to-mesenchymal transition by targeting ETS1. Our data highlight PTPN18 as a suppressor of breast cancer metastasis and provide an effective antimetastatic therapeutic strategy.

Breast cancer cells-derived Von Willebrand Factor promotes VEGF-A-related angiogenesis through PI3K/Akt-miR-205-5p signaling pathway

The metastasis and angiogenesis of breast cancer has always been a difficult problem for treatment. It has recently been discovered that Von Willebrand Factor (vWF), in addition to hemostasis, also plays a role in tumor metastasis and angiogenesis. We noticed that besides endothelial cells, breast cancer cells (MDA-MB-231 and MCF-7) could also express vWF. In vitro experiments showed that knocking down vWF inhibited breast cancer cell metastasis. And we found that overexpression of vWF significantly promoted VEGF-A-dependent vascular proliferation in vitro by activating the PI3K/Akt signaling pathway. Further studies indicated that inhibition of PI3K/Akt signaling pathway up-regulated the expression of miR-205-5p, and miR-205-5p could bind to the 3′UTR region of VEGF-A to hinder the production of VEGF-A. Furthermore, when a spontaneous lung metastasis model was established in Balb/c female mice, knockdown of vWF in 4 T1 cells resulted in a decrease in tumor blood vessel density and effectively inhibited lung metastasis, accompanied by a decrease in the expression level of VEGF-A and an increase in the expression level of miR-205-5p. In summary, our findings provide experimental evidence that overexpression of vWF in breast cancer cells down-regulates the expression of miR-205-5p and up-regulates the expression of VEGF-A through the PI3K/Akt signaling pathway, thereby promoting tumor angiogenesis and metastasis.

The 14-3-3η/GSK-3β/β-catenin complex regulates EndMT induced by 27-hydroxycholesterol in HUVECs and promotes the migration of breast cancer cells.

Endothelial-mesenchymal transition (EndMT) is the transformation of endothelial cell morphology to mesenchymal cell morphology, accompanied by decline of endothelial function and enhancement of mesenchymal function, which promotes tumor progression and tumor cell invasion and metastasis. 27-Hydroxycholesterol (27-HC) is a cholesterol metabolite, which has a high content in human blood. 27-HC promotes breast cancer cell proliferation, invasion, and migration. We previously showed that 27-HC promotes EndMT; however, the underlying mechanism still needs to be further explored. We studied the role of the 14-3-3η/GSK-3β/β-catenin complex in EndMT. Our results show that 27-HC induces oxidative stress in HUVECs and activates the p38 signaling pathway, thereby inhibiting the binding of 14-3-3η/GSK-3β/β-catenin, promoting the increase of free β-catenin and nuclear translocation, and finally inducing EndMT. Treatment with N-acetylcysteine (NAC) blocked 27-HC-induced ROS generation and p38 signaling pathway activation, prevented β-catenin from release from binding, and inhibited EndMT. Blocking ROS production or p38 signaling or knocking down 14-3-3η inhibited 27-HC-induced EndMT and inhibited breast cancer cell metastasis. These findings indicate 14-3-3η is necessary for interactions between the p38 kinase and the GSK-3β/β-catenin complex and serves as an adaptor to transmit the upstream kinase signal to the downstream signal, thereby promoting EndMT and breast cancer cell migration.

Osteocytes and Bone Metastasis.

Bone is the most frequent site of breast cancer and prostate cancer metastasis, and one of the most common sites of metastasis for many solid tumors. Once cancer cells colonize in the bone, it imposes a major clinical challenge for the treatment of the disease, and fatality rates increase drastically. Bone, the largest organ in the body, provides a fertile microenvironment enriched with nutrients, growth factors and hormones, a generous reward for cancer cells. Dependent on cancer type, cancer cells can cause osteoblastic (bone forming) or osteolytic lesions to promote the net resorption and/or release of growth factors from the bone extracellular matrix. These processes activate a “vicious cycle”, leading to disruption of bone integrity and promoting cancer cell growth and migration. Cancer cells influence the bone microenvironment favoring their colonization and growth. In order to metastasize to the bone, cancer cells must first migrate from the site of origin, and once established within the bone, they must overcome the dormant inducing effects of resident cells. If successful, cancer cells can then colonize and continually disrupt bone homeostasis that is primarily maintained by osteocytes, the most abundant bone cell type. For example, it has been shown that exercise induces osteocytes to release anabolic factors that inhibit osteoclast resorptive activity, promote dormancy and the release of anti-cancer factors that inhibit breast cancer cell metastasis. In this review, we will summarize recent research findings and provide mechanistic insights related to the role of osteocytes in osteolytic metastasis.

Baicalin inhibits the TGF-β1/p-Smad3 pathway to suppress epithelial-mesenchymal transition-induced metastasis in breast cancer.

TGF-β1 is an epithelial-mesenchymal transition (EMT)-inducing factor that is critical in tumor progression. However, whether the effect of TGF-β1 on breast cancer is through the EMT pathway remains to be determined, and drug development based on this mechanism needs to be improved. Results of this study showed that TGF-β1 dysregulation significantly correlated with the expression levels of EMT-associated markers and transcriptional factors. Exogenous expression of TGF-β1 promoted breast cancer cell metastasis and EMT progression. In addition, direct binding of baicalin to TGF-β1 caused its inactivation, which subsequently blocked signal transduction and inhibited breast cancer cell metastasis. In vivo experiment results further invalidated the inhibitory effect of baicalin on TGF-β1-induced tumor metastasis. These results suggest that baicalin, an active ingredient used in traditional Chinese medicine, exhibits a potential therapeutic effect on breast cancer metastasis by regulating TGF-β1-dependent EMT progression.

Triptolide Inhibits Breast Cancer Cell Metastasis Through Inducing the Expression of miR-146a, a Negative Regulator of Rho GTPase.

Triptolide, an extract of Tripterygium wilfordii, has been shown to have a potent anticancer activity. In the present study, it was found that triptolide could effectively induce apoptosis and inhibit proliferation and invasion in malignant MDA-MB-231 breast cancer cells. The study focused on its effect on inhibiting invasion, which has not been extensively reported to date. We predicted that triptolide may change invasion activity via microRNAs (miRNAs), which have been recognized as important regulators of gene expression. miRNAome variation in MDA-MB-231 cells with or without triptolide treatment demonstrated that miR-146a was upregulated following treatment with triptolide. Our previous studies have shown that miR-146a can inhibit migration and invasion by targeting RhoA in breast cancer. This time, we found that miR-146a can target Rac1, another key member of the Rho GTPase family. Luciferase reporter containing Rac1 3′-UTR was constructed to prove this hypothesis. In addition, following treatment with triptolide, the expression of RhoA and Rac1 was found to be decreased. These results indicated that triptolide exerts its anti-invasion activity through a miRNA-mediated mechanism, which indirectly regulates the expression of Rho GTPase. Triptolide combined with miR-146a could improve the effect of triptolide treatment on breast cancer.

Honokiol inhibits breast cancer cell metastasis by blocking EMT through modulation of Snail/Slug protein translation

Honokiol (HNK), an active compound isolated from traditional Chinese medicine Magnolia officinalis, has shown potent anticancer activities. In the present study, we investigated the effects of HNK on breast cancer metastasis in vitro and in vivo, as well as the underlying molecular mechanisms. We showed that HNK (10-70 μmol/L) dose-dependently inhibited the viability of human mammary epithelial tumor cell lines MCF7, MDA-MB-231, and mouse mammary tumor cell line 4T1. In the transwell and scratch migration assays, HNK (10, 20, 30 μmol/L) dose-dependently suppressed the invasion and migration of the breast cancer cells. We demonstrated that HNK (10-50 μmol/L) dose-dependently upregulated the epithelial marker E-cadherin and downregulated the mesenchymal markers such as Snail, Slug, and vimentin at the protein level in breast cancer cells. Using a puromycin incorporation assay, we showed that HNK decreased the Snail translation efficiency in the breast cancer cells. In a mouse model of tumor metastasis, administration of HNK (50 mg/kgevery day, intraperitoneal (i.p.), 6 times per week for 30 days) significantly decreased the number of metastatic 4T1 cell-derived nodules and ameliorated the histological alterations in the lungs. In addition, HNK-treated mice showed decreased Snail expression and increased E-cadherin expression in metastatic nodules. In conclusion, HNK inhibits EMT in the breast cancer cells by downregulating Snail and Slug protein expression at the mRNA translation level. HNK has potential as an integrative medicine for combating breast cancer by targeting EMT.

ACE2 inhibits breast cancer angiogenesis via suppressing the VEGFa/VEGFR2/ERK pathway

BackgroundBreast cancer angiogenesis is key for metastasis and predicts a poor prognosis. Angiotensin-converting enzyme 2 (ACE2), as a member of the renin-angiotensin system (RAS), was reported to restrain the progression of hepatocellular carcinoma (HCC) and non-small cell lung cancer (NSCLC) through inhibiting angiogenesis. However, the relationship between ACE2 and breast cancer angiogenesis remains unclear.MethodsThe prognosis and relative gene selection were analysed using the GEPIA, GEO, TCGA and STRING databases. ACE2 expression in breast cancer tissue was estimated by reverse transcription-quantitative polymerase chain reaction (qPCR). Breast cancer cell migration, proliferation and angiogenesis were assessed by Transwell migration, proliferation, tube formation, and wound healing assays. The expression of vascular endothelial growth factor A (VEGFa) was detected by qPCR and Western blotting. The phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2), mitogen-activated protein kinase 1/2 (MEK1/2), and extracellular signal-regulated protein kinase 1/2 (ERK1/2) was examined by Western blotting. Breast cancer metastasis and angiogenesis in vivo were measured using a zebrafish model.ResultsACE2 was downregulated in breast cancer patients. Patients with higher ACE2 expression had longer relapse-free survival (RFS). In vitro, ACE2 inhibited breast cancer migration. Meanwhile, ACE2 in breast cancer cells inhibited human umbilical vascular endothelial cell (HUVEC) proliferation, tube formation and migration. In the zebrafish model, ACE2 inhibited breast cancer cell metastasis, as demonstrated by analyses of the number of disseminated foci and the metastatic distance. Neo-angiogenesis was also decreased by ACE2. ACE2 downregulated the expression of VEGFa in breast cancer cells. Furthermore, ACE2 in breast cancer cells inactivated the phosphorylation of VEGFR2, MEK1/2, and ERK1/2 in HUVECs.ConclusionsOur findings suggest that ACE2, as a potential resister to breast cancer, might inhibit breast cancer angiogenesis through the VEGFa/VEGFR2/ERK pathway.Trial registrationRetrospectively registered.

Increased expression of miR-1179 inhibits breast cancer cell metastasis by modulating Notch signaling pathway and correlates with favorable prognosis.

MicroRNAs (miRNAs) play a key role in the regulation of gene expression. In this study, we aimed to identify the clinical values of miR-1179 and to investigate the potential molecular mechanisms in breast cancer (BC). RT-PCR was used to detect the expression levels of miR-1179 in both BC tissues and cell lines. We analyzed the association between the miR-1179 levels and clinicopathological factors and patient prognosis. The proliferation ability of miR-1179 on BC cells was assessed by MTT and colony formation assay. The role of miR-1179 in BC cells migration and invasion was measured by transwell assays. Western blot analysis was used to quantify the expression of the molecular biomarkers of the Notch signaling pathway. Our results showed that miR-1179 expression was frequently downregulated in BC tissues and cell lines. Clinicopathologic analysis revealed that low miR-1179 expression is correlated with lymph node metastasis, advanced clinical stage and shorter overall survival. Multivariable Cox proportional hazards regression analysis suggested that increased miR-1179 expression was an independent prognostic factor of overall survival in BC patients. Gain-of-function assay indicated that the overexpression of miR-1179 significantly suppressed BC cells proliferation, migration and invasion. Mechanistically, miR-1179 up-regulation inhibited the expression of Notch 1, Notch 4 and Hes1, indicating that miR-1179 could suppress the activation of the Notch signaling pathway. We showed that miR-1179 was a tumor suppressor that may serve as a novel potential prognostic biomarker or molecular therapeutic target for BC.

RNA Binding Protein RNPC1 Inhibits Breast Cancer Cell Metastasis via Activating STARD13-Correlated ceRNA Network.

RNA binding proteins (RBPs) are pivotal post-transcriptional regulators. RNPC1, an RBP, acts as a tumor suppressor through binding and regulating the expression of target genes in cancer cells. This study disclosed that RNPC1 expression was positively correlated with breast cancer patients' relapse-free and overall survival and that RNPC1 suppressed breast cancer cell metastasis. Mechanistically, RNPC1 promotes competing endogenous RNA (ceRNA) network crosstalk among STARD13, CDH5, HOXD10, and HOXD1 (STARD13-correlated ceRNA network), which we previously confirmed in breast cancer cells through stabilizing the transcripts and thus facilitating the expression of these four genes in breast cancer cells. Furthermore, RNPC1 overexpression restrained the promotion of STARD13, CDH5, HOXD10, and HOXD1 knockdown on cell metastasis. Notably, RNPC1 expression was positively correlated with CDH5, HOXD1, and HOXD10 expression in breast cancer tissues and attenuated adriamycin resistance. Taken together, these results identified that RNPC1 could inhibit breast cancer cell metastasis via promoting a STARD13-correlated ceRNA network.

MicroRNA-708-3p mediates metastasis and chemoresistance through inhibition of epithelial-to-mesenchymal transition in breast cancer.

Metastasis and chemoresistance remain major challenges in the clinical treatment of breast cancer. Recent studies show that dysregulated microRNAs (miRNAs) play an important role in metastasis and chemoresistance development in breast cancer. Herein, we identified downregulated expression of miR‐708‐3p in breast cancers. In particular, miR‐708‐3p expression was significantly decreased in specimens from breast cancer patients with metastasis compared to that in specimens from patients with no metastasis. Consistent with clinical data, our in vitro data show that miR‐708‐3p was more significantly decreased in invasive breast cancer cell lines. In addition, our data show that inhibition of miR‐708‐3p significantly stimulated breast cancer cell metastasis and induced chemoresistance both in vitro and in vivo. In contrast, overexpression of miR‐708‐3p dramatically inhibited breast cancer cell metastasis and enhanced the sensitivity of breast cancer cells to chemotherapy both in vitro and in vivo. Furthermore, we identified that miR‐708‐3p inhibits breast cancer cell epithelial‐to‐mesenchymal transition (EMT) by directly targeting EMT activators, including ZEB1, CDH2 and vimentin. Taken together, our findings suggest that miR‐708‐3p acts as a cancer suppressor miRNA and carries out its anticancer function by inhibiting EMT in breast cancer. In addition, our findings suggest that restoration of miR‐708‐3p may be a novel strategy for inhibiting breast cancer metastasis and overcoming the chemoresistance of breast cancer cells.

Extracts of Cordyceps sinensis inhibit breast cancer cell metastasis via down-regulation of metastasis-related cytokines expression

Ethnopharmacological relevanceCordyceps sinensis is a traditional Chinese medicine and has been used as adjuvant treatments for cancer and it has been also demonstrated to be effective in cancer patients. Aim of the studyThe objective of the present study is to investigate the anti-metastasis effects of water extracts of Cordyceps sinensis (WECS) in breast cancer and the potential mechanisms. Materials and methodsThe cytotoxicity of WECS on 4T1 breast cancer cells was evaluated in vitro using cell counting kit-8 (CCK8) assay. The in vivo anti-metastatic activity of intraperitoneally administered WECS and its effect on animal survival were measured in a mouse breast cancer metastasis model. To explore the molecular mechanisms of the anti-metastasis effect of WECS, the expression of matrix metalloprotein-9 (MMP-9) in serum was determined by enzyme-linked immunosorbent assay (ELISA). In addition, a protein array was used to examine the cytokine expression profiles in lung homogenates. ResultsTreatment with WECS (0.10–0.40mg/ml) significantly inhibited 4T1 cell viability in vitro. In animal studies, 50mg/kg WECS significantly reduced the number of metastatic lung nodules and the weight of lung, without affecting body weight of mice. Furthermore, WECS increased the survival rate of 4T1 tumor bearing mice in a dose dependent manner, and at high dose, WECS (50mg/kg) significantly increased the life span of the mice compared to untreated control group. The expression level of MMP-9 in serum was decreased about 50% in 50mg/kg WECS treated group compared to control group. The results of protein array showed that the expression of CC chemokine ligand 17 (CCL17), MMP-9, osteopontin (OPN), interleukin-33 (IL-33), CC chemokine ligand 12 (CCL12) and CC chemokine ligand 6 (CCL6) in the lungs of 4T1 tumor bearing mice was increased more than two fold compared with normal mice. Among them, the expression of CCL17, MMP-9, OPN, IL-33 was significantly reduced by treatment of 50mg/kg WECS. ConclusionOur results demonstrated that WECS has potent anti-metastasis activity in a mouse breast cancer metastasis model possibly by down-regulation the expression of several metastasis-related cytokines.

Mechanistic Study of Bakuchiol-Induced Anti-breast Cancer Stem Cell and in Vivo Anti-metastasis Effects.

Cancer stem cells are involved in cancer establishment, progression, and resistance to current treatments. We demonstrated the in vitro and in vivo anti-breast cancer effect of bakuchiol in a previous study. However, the ability of bakuchiol to target breast cancer stem cells (BCSCs) and inhibit breast cancer metastasis remains unknown. In the current study, we used the cell surface markers CD44 and CD24 to distinguish BCSCs from MCF-7 cells. Bakuchiol inhibited mammosphere formation and aldehyde dehydrogenase activity in BCSCs. Moreover, bakuchiol induced apoptosis and suppressed the mitochondrial membrane potential of BCSCs. Bakuchiol upregulated the expression levels of pro-apoptotic genes, BNIP3 and DAPK2. Bakuchiol induced oxidative stress and altered lipogenesis in BCSCs. In zebrafish xenografts, bakuchiol inhibited breast cancer cell metastasis in vivo. In addition, bakuchiol altered the expression levels of metastasis-related genes through upregulating CK18 and downregulating Notch3, FASN, TGFBR1, and ACVR1B. Our study provides evidence for the anti-breast cancer potential of bakuchiol.

The CD44s splice isoform is a central mediator for invadopodia activity.

The ability for tumor cells to spread and metastasize to distant organs requires proteolytic degradation of extracellular matrix (ECM). This activity is mediated by invadopodia, actin-rich membrane protrusions that are enriched for proteases. However, the mechanisms underlying invadopodia activity are not fully understood. Here, we report that a specific CD44 splice isoform, CD44s, is an integral component in invadopodia. We show that CD44s, but not another splice isoform CD44v, is localized in invadopodia. Small hairpin (sh)RNA-mediated depletion of CD44s abolishes invadopodia activity, prevents matrix degradation and decreases tumor cell invasiveness. Our results suggest that CD44s promotes cortactin phosphorylation and recruits MT1-MMP (also known as MMP14) to sites of matrix degradation, which are important activities for invadopodia function. Importantly, we show that depletion of CD44s inhibits breast cancer cell metastasis to the lung in animals. These findings suggest a crucial mechanism underlying the role of the CD44s splice isoform in breast cancer metastasis.

Abstract 4650: Novel resveratrol-analog HPIMBD inhibits breast cancer cell metastasis by reversal of epithelial-mesenchymal transition

Abstract Epithelial-mesenchymal transition (EMT) is a biological process that mediates a phenotypical change in the polarized epithelial cells to mesenchymal cells. The process of EMT increases a cell's migratory and invasive properties. It is well documented that the process of EMT plays a very critical role in cancer metastasis. The objective of this study was to characterize the role of a novel Resveratrol analog 4-(E)-{4-hydroxyphenylimino)-methylbenzene, 1,2-diol} (HPIMBD) on EMT in human breast cancer cells. Human breast cancer cells MDA-MB-231 were treated with Resveratrol (Res) and HPIMBD for up to 48 hours. Protein expression levels of E-cadherin, matrix metalloproteases (MMPs), snail, slug, zeb1/2 and nuclear migration of β-catenin were quantified after treatment with Res or HPIMBD and compared with that of the vehicle-treated control cells. mRNA expression levels of β-catenin and wnt-7b were also quantified. Migration MDA-MB-231 cells was determined after treatment with Res or HPIMBD by wound healing assay. Treatment with HPIMBD significantly up-regulated E-cadherin protein expression levels. The up-regulation of E-cadherin by HPIMBD was associated with suppression of snail, slug and Zeb1 protein levels. HPIMBD significantly down-regulated mRNA expression levels of β-catenin and wnt-7b. Furthermore, HPIMBD restricted nuclear migration of β-catenin. Treatment of breast cancer cells with HPIMBD resulted in down-regulation of MMP3 and MMP9 but not MMP2 protein expression levels. Treatment with HPIMBD also prevented breast cancer cell migration. Our studies demonstrtae that HPIMBD decreases the metastatic properties of breast cancer cells by inhibition of EMT and down-regulation of wnt/β catenin pathway. These findings suggest that HPIMBD may have a potential in inhibtion of EMT and may be explored as as a potential therapy to prevent breast cancer metastasis. Note: This abstract was not presented at the meeting. Citation Format: Anwesha Chatterjee, Amruta Ronghe, Subhash Padhye, Hari K. Bhat. Novel resveratrol-analog HPIMBD inhibits breast cancer cell metastasis by reversal of epithelial-mesenchymal transition. [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 4650. doi:10.1158/1538-7445.AM2015-4650

Phenformin Induces Cell Cycle Change, Apoptosis, and Mesenchymal-Epithelial Transition and Regulates the AMPK/mTOR/p70s6k and MAPK/ERK Pathways in Breast Cancer Cells.

Breast cancer remains a world-wide challenge, and additional anti-cancer therapies are still urgently needed. Emerging evidence has demonstrated the potent anti-tumor effect of biguanides, among which phenformin was reported to potentially be a more active anti-cancer agent than metformin. However, little attention has been given to the role of phenformin in breast cancer. In this study, we reveal the role of phenformin in cell death of the MCF7, ZR-75-1, MDA-MB-231 and SUM1315 breast cancer cell lines. The respective IC50 values of phenformin in MCF7, ZR-75-1, MDA-MB-231 and SUM1315 cells were 1.184±0.045 mM, 0.665±0.007 mM, 2.347±0.010 mM and 1.885±0.015 mM (mean± standard error). Phenformin induced cell cycle change and apoptosis in breast cancer cells via the AMPK/mTOR/p70s6k and MAPK/ERK pathways. Interestingly, phenformin induced MET (mesenchymal-epithelial transition) and decreased the migration rate in breast cancer cell lines. Furthermore, our results suggest that phenformin inhibits breast cancer cell metastasis after intracardiac injection into nude mice. Taken together, our study further confirms the potential benefit of phenformin in breast cancer treatment and provides novel mechanistic insight into its anti-cancer activity in breast cancer.

GPR116, an Adhesion G-Protein–Coupled Receptor, Promotes Breast Cancer Metastasis via the Gαq-p63RhoGEF-Rho GTPase Pathway

Adhesion G-protein-coupled receptors (GPCR), which contain adhesion domains in their extracellular region, have been found to play important roles in cell adhesion, motility, embryonic development, and immune response. Because most adhesion molecules with adhesion domains have vital roles in cancer metastasis, we speculated that adhesion GPCRs are potentially involved in cancer metastasis. In this study, we identified GPR116 as a novel regulator of breast cancer metastasis through expression and functional screening of the adhesion GPCR family. We found that knockdown of GPR116 in highly metastatic (MDA-MB-231) breast cancer cells suppressed cell migration and invasion. Conversely, ectopic GPR116 expression in poorly metastatic (MCF-7 and Hs578T) cells promoted cell invasion. We further showed that knockdown of GPR116 inhibited breast cancer cell metastasis in two mammary tumor metastasis mouse models. Moreover, GPR116 modulated the formation of lamellipodia and actin stress fibers in cells in a RhoA- and Rac1-dependent manner. At a molecular level, GPR116 regulated cell motility and morphology through the Gαq-p63RhoGEF-RhoA/Rac1 pathway. The biologic significance of GPR116 in breast cancer is substantiated in human patient samples, where GPR116 expression is significantly correlated with breast tumor progression, recurrence, and poor prognosis. These findings show that GPR116 is crucial for the metastasis of breast cancer and support GPR116 as a potential prognostic marker and drug target against metastatic human breast cancer.

BRCC2 inhibits breast cancer cell growth and metastasis in vitro and in vivo via downregulating AKT pathway

In our previous study, we demonstrated that the BRCC2 (breast cancer cell 2) gene is a proapoptotic molecule that interacts with Bcl-XL. BRCC2 downregulation is associated with poor disease-free and overall survival in breast cancer. In this study, we aimed to investigate the role of BRCC2 in tumor suppression in breast cancer. In clinical breast cancer samples, we found that BRCC2 expression was significantly downregulated in cancer lesions compared with paired normal breast tissues. By silencing or overexpressing BRCC2 in breast cancer cells, we found that BRCC2 could inhibit cell growth and metastasis in vitro. An in vivo assay showed that BRCC2 not only dramatically inhibited breast cancer cell xenograft formation and growth but also inhibited breast cancer cell metastasis in a lung metastasis model. Moreover, we demonstrated that BRCC2 inhibited breast cancer metastasis via regulation of the Akt pathway. Thus, our study provided evidence that BRCC2 functions as a novel tumor suppressor in breast cancer and may be a potential therapeutic target for breast cancer management.

Dietary stearate reduces human breast cancer metastasis burden in athymic nude mice

Stearate is an 18-carbon saturated fatty acid found in many foods in the western diet, including beef and chocolate. Stearate has been shown to have anti-cancer properties during early stages of neoplastic progression. However, previous studies have not investigated the effect of dietary stearate on breast cancer metastasis. In this study, we present evidence that exogenously supplied dietary stearate dramatically reduces the size of tumors that formed from injected human breast cancer cells within the mammary fat pads of athymic nude mice by approximately 50% and partially inhibits breast cancer cell metastasis burden in the lungs in this mouse model system. This metastatic inhibition appears to be independent of primary tumor size, as stearate fed animals that had primary tumors comparable in size to littermates fed either a safflower oil enriched diet or a low fat diet had reduced lung metastasis. Also stearate fed mice sub-groups had different primary tumor sizes but no difference in metastasis. This anti-metastasis effect may be due, at least in part, to the ability of stearate to induce apoptosis in these human breast cancer cells. Overall, this study suggests the possibility of dietary manipulation with selected long-chain saturated fatty acids such as stearate as a potential adjuvant therapeutic strategy for breast cancer patients wishing to maximize the suppression of metastatic disease.