CDDO, a PPAR‑γ ligand, inhibits TPA‑induced cell migration and invasion through a PPAR‑γ‑independent mechanism

Peroxisome proliferator-activated receptor-γ (PPAR-γ) acts as a key factor in breast cancer metastasis. Notably, PPAR-γ can inhibit metalloproteinase (MMP), which is involved in cancer metastasis. Our previous study revealed that PPAR-γ was related to breast cancer metastasis. The present study aimed to investigate whether the PPAR-γ ligand 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) mediated suppression of cell invasion and reduced the expression of MMP-9 in breast cancer cells. The results indicated that CDDO reduced MMP-9 expression, cell migration and invasion of breast cancer cells by inhibiting TPA-induced phosphorylation of mitogen-activated protein kinases, and downregulating the activities of activator protein-1 and nuclear factor κB. Notably, knock-out of PPAR-γ by small interfering RNA in MCF-7 cells revealed that TPA-induced MMP-9 expression occurred through a PPAR-γ-independent pathway. These data indicated that the downregulatory effect of CDDO on MMP-9 expression was affected by a mechanism independent of PPAR-γ. In conclusion, the findings of the present study suggested that CDDO may act as a key agent in the regulation of breast cancer metastasis, suggesting CDDO as a new targeted therapy for breast cancer.

Inhibition of cell invasion and migration by targeting matrix metalloproteinase-9 expression via sirtuin 6 silencing in human breast cancer cells

Sirtuin 6 (SIRT6) regulation is involved in carcinogenesis. However, its role in breast cancer (BC) metastasis remains unclear. We investigated the effects of SIRT6 on protein kinase C activator- and cytokine-mediated cancer cell invasion and migration in MCF-7 and MDA-MB-231 cells and the association between SIRT6 and matrix metalloproteinase-9 (MMP-9) expression. To assess MMP-9 and SIRT6 expression in patients, protein levels in BC tissues were analyzed. MCF-7 and MDA-MB-231 cell viability was analyzed using MTT assays. SIRT6 was silenced in both cell lines and protein secretion, expression, and mRNA levels were analyzed. Transcription factor DNA activity was investigated using luciferase assays. Matrigel invasion assays were used to assess the effects of SIRT6 in both cell lines. SIRT6 and MMP-9 expression in cancer tissues was significantly higher than in paired normal breast tissues. 12-O-tetradecanoylphorbol-13-acetate (TPA) or tumor necrosis factor-α (TNF-α) increased MMP-9 expression and cell invasion and migration, but SIRT6 knockdown abolished these effects. SIRT6 overexpression additively increased TPA- and TNF-α-induced MMP-9 expression. SIRT6 knockdown suppressed the mitogen-activated protein kinase (MAPK) signaling pathway and thus TPA- and TNF-α-induced MMP-9 expression. SIRT6 silencing suppressed TPA- and TNF-α-induced nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) expressions in both cell lines, and treatment with MAPK, NF-κB, and AP-1 inhibitors reduced MMP-9 expression. The anti-invasive effects of SIRT6 in BC cells might be mediated by suppression of MAPK phosphorylation and reduction in NF-κB and AP-1 DNA activities, leading to MMP-9 downregulation, suggesting that SIRT6 modulation has the potential to target BC metastasis.

Triptolide inhibits matrix metalloproteinase-9 expression and invasion of breast cancer cells through the inhibition of NF-κB and AP-1 signaling pathways

Triptolide is a diterpenoid epoxide that is endogenously produced by the thunder god vine, Tripterygium wilfordii Hook F. Triptolide has demonstrated a variety of biological activities, including anticancer activities, in previous studies. Invasion and metastasis are the leading causes of mortality for patients with breast cancer, and the increased expression of matrix metalloproteinase-9 (MMP-9) has been shown to be associated with breast cancer invasion. Therefore, the aim of the present study was to investigate the effect of triptolide on 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced cell invasion and MMP-9 expression in breast cancer cells. The expression of signal molecules was examined by western blotting, zymography and quantitative polymerase chain reaction; an electrophoretic mobility gel shift assay was also used, and cell invasiveness was measured by an in vitro Matrigel invasion assay. The MCF-7 human breast cancer cell line was treated with triptolide at the highest concentrations at which no marked cytotoxicity was evident. The results demonstrated that triptolide decreased the expression of MMP-9 through inhibition of the TPA-induced phosphorylation of extracellular signal-regulated kinase (ERK) and the downregulation of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activity. In addition, a Transwell assay revealed that triptolide reduced the ability of MCF-7 cells to invade Matrigel. These data demonstrate that the anti-invasive effect of triptolide is associated with the inhibition of ERK signaling and NF-κB and AP-1 activation, and suggest that triptolide may be a promising drug for breast cancer.

15d-PGJ2 inhibits NF-κB and AP-1-mediated MMP-9 expression and invasion of breast cancer cell by means of a heme oxygenase-1-dependent mechanism

Activation of peroxisome proliferator-activated receptor γ (PPARγ) serves as a key factor in the proliferation and invasion of breast cancer cells and is a potential therapeutic target for breast cancer. However, the mechanisms underlying this effect remain largely unknown. Heme oxygenase-1 (HO-1) is induced and over-expressed in various cancers and is associated with features of tumor aggressiveness. Recent studies have shown that HO-1 is a major downstream target of PPARγ. In this study, we investigated the effects of induction of HO-1 by PPARγ on TPA-induced MMP-9 expression and cell invasion using MCF-7 breast cancer cells. TPA treatment increased NF-μB /AP-1 DNA binding as well as MMP-9 expression. These effects were significantly blocked by 15d-PGJ₂, a natural PPARγ ligand. 15d-PGJ₂ induced HO-1 expression in a dose-dependent manner. Interestingly, HO-1 siRNA significantly attenuated the inhibition of TPA-induced MMP-9 protein expression and cell invasion by 15d-PGJ₂. These results suggest that 15d-PGJ₂ inhibits TPA-induced MMP-9 expression and invasion of MCF-7 cells by means of a heme oxygenase-1-dependent mechanism. Therefore, PPARγ/HO-1 signaling-pathway inhibition may be beneficial for prevention and treatment of breast cancer.

Roles of JNK/Nrf2 Pathway on Hemin-Induced Heme Oxygenase-1 Activation in MCF-7 Human Breast Cancer Cells

Heme oxygenase-1 (HO-1) is highly induced in various human disease states, including cancer, indicating that HO-1 is an emerging target of cancer therapy. In this study, we investigated that the mechanisms of hemin-induced HO-1 expression and its signaling pathways in human breast cancer cell. We used MCF-7 cells, a human breast cancer cell line. Hemin increased HO-1 expression in MCF-7 cells in a dose- and time-dependent manner. Hemin enhanced HO-1 expression through the activation of c-Jun N-terminal kinases (JNK) signaling pathway. Hemin also induced activation of Nrf2, a major transcription factor of HO-1 expression. These responses in MCF-7 cells were completely blocked by pretreatment with brazilin, a HO-1 regulator. These results indicated that brazilin inhibits hemin-induced HO-1 expressions through inactivation of JNK/Nrf2 in MCF-7 cells. Thus, our findings suggest that HO-1 is an important anticancer-target of brazilin in human breast cancer.

Troglitazone Inhibits Matrix Metalloproteinase-9 Expression and Invasion of Breast Cancer Cell through a Peroxisome Proliferator-Activated Receptor γ-Dependent Mechanism

Purpose

Peroxisome proliferator-activated receptor γ (PPARγ) is involved in the pathology of numerous diseases including atherosclerosis, diabetes, obesity, and cancer. Matrix metalloproteinases (MMPs) play a significant role in tissue remodeling related to various processes such as morphogenesis, angiogenesis, tissue repair, invasion, and metastasis. We investigated the effects of PPARγ on MMP expression and invasion in breast cancer cells.

Methods

MCF-7 cells were cultured and then cell viability was monitored in an MTT assay. Western blotting, gelatin zymography, real-time polymerase chain reaction, and luciferase assays were performed to investigate the effect of the synthetic PPARγ ligand troglitazone on MMP expression. Transcription factor DNA binding was analyzed by electrophoretic mobility shift assay. A Matrigel invasion assay was used to assess the effects of troglitazone on MCF-7 cells.

Results

Troglitazone did not affect MCF-7 cell viability. 12-O-tetradecanoylphorbol-13-acetate (TPA) induced MMP-9 expression and invasion in MCF-7 cell. However, these effects were decreased by troglitazone. TPA increased nuclear factor κB and activator protein-1 DNA binding, while troglitazone inhibited these effects. The selective PPARγ antagonist GW9662 reversed MMP-9 inhibition by troglitazone in TPA-treated MCF-7 cells.

Conclusion

Troglitazone inhibited nuclear factor κB and activator protein-1-mediated MMP-9 expression and invasion of MCF-7 cells through a PPARγ-dependent mechanism.

Anti-cancer Effect of Cyanidin-3-glucoside from Mulberry via Caspase-3 Cleavage and DNA Fragmentation in vitro and in vivo

BACKGROUND

Fruits of Morus alba L. (mulberry) have various bioactive compounds such as polyphenols and anthocyanins and used as a herbal medicine. However, the anti-cancer effects and molecular basis have not been elucidated.

METHODS

We isolated the cyanidin-3-glucoside in various cultivar of mulberry by acidified-methanol extraction methods. This molecule were compared mass spectroscopic properties by LC-MS/MS and analyzed by 1H and 13C NMR. We examined the anti-cancer effect with molecular mechanisms of the cyanidin-3-glucoside on MDA-MB-453 human breast cancer cells and xenograft animal model.

RESULTS

The treatment with the mulberry cyanidin-3-glucoside decreased cell viability in a dose-dependent manner with alteration of apoptotic protein contents, and DNA fragmentation, suggesting that cells undergo apoptosis. Supporting the observations, Treatment with the cyanidin-3-glucoside showed active apoptosis by caspase-3 cleavage and DNA fragmentation through Bcl-2 and Bax pathway. Indeed, cyanidin-3-glucoside inhibits tumor growth in MDA-MB-453 cells-inoculated nude mice. Tumor growth of xenograft nude mouse was significantly reduced compared to the control group by the cyanidin-3-glucoside.

CONCLUSION

The data demonstrate that cyanidin-3-glucoside isolated from mulberry induced apoptosis in breast cancer (MDA-MB-453) cells, and therefore, has a potential as an anti-cancer agent. These results show that mulberry cyanidin-3-glucoside inhibit the proliferation and growth in vitro and in vivo model and, indicating the inhibition of tumor progression.

PTEN inhibits replicative senescence-induced MMP-1 expression by regulating NOX4-mediated ROS in human dermal fibroblasts

The biological function of NADPH oxidase (NOX) is the generation of reactive oxygen species (ROS). ROS, primarily arising from oxidative cell metabolism, play a major role in both chronological ageing and photoageing. ROS in extrinsic and intrinsic skin ageing may be assumed to induce the expression of matrix metalloproteinases. NADPH oxidase is closely linked with phosphatidylinositol 3‐OH kinase (PI3K) signalling. Protein kinase C (PKC), a downstream molecule of PI3K, is essential for superoxide generation by NADPH oxidase. However, the effect of PTEN and NOX4 in replicative‐aged MMPs expression has not been determined. In this study, we confirmed that inhibition of the PI3K signalling pathway by PTEN gene transfer abolished the NOX‐4 and MMP‐1 expression. Also, NOX‐4 down‐expression of replicative‐aged skin cells abolished the MMP‐1 expression and ROS generation. These results suggest that increase of MMP‐1 expression by replicative‐induced ROS is related to the change in the PTEN and NOX expression.

Epigallocatechin gallate inhibits the growth of MDA-MB-231 breast cancer cells via inactivation of the β-catenin signaling pathway

Epigallocatechin gallate (EGCG), a major constituent of green tea, has potential as a treatment for a variety of diseases, including cancer. EGCG induces apoptosis and inhibits tumorigenesis through multiple signaling pathways in breast cancer cells. β-catenin signaling modulators could be useful in the prevention and therapy of breast cancer. However, the precise anticancer effect of EGCG through the β-catenin signaling pathway in breast cancer is unclear. The present study investigated the association between β-catenin expression and clinicopathological factors of breast cancer patients, and the effect of EGCG on β-catenin expression in breast cancer cells. β-catenin expression was analyzed according to the clinicopathological factors of 74 patients with breast cancer. All patients were females diagnosed with invasive ductal carcinoma. Western blot analysis revealed that β-catenin was expressed at higher levels in breast cancer tissue than in normal tissue. β-catenin expression was associated with lymph node metastasis (P=0.04), tumor-node-metastasis stage (P=0.03) and estrogen receptor status (P<0.01). EGCG decreased MDA-MB-231 cell viability and significantly downregulated the expression of β-catenin, phosphorylated Akt and cyclin D1. Remarkably, additive effects of LY294002 and wortmannin, two phosphatidylinositol-3 kinase inhibitors, were observed. The present results suggest that EGCG inhibits the growth of MDA-MB-231 cells through the inactivation of the β-catenin signaling pathway. Based on these promising results, EGCG may be a potential treatment for triple negative breast cancer patients.

DHA blocks TPA-induced cell invasion by inhibiting MMP-9 expression via suppression of the PPAR-γ/NF-κB pathway in MCF-7 cells

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is considered to have applications in cancer prevention and treatment. The beneficial effects of DHA against cancer metastasis are well established; however, the mechanisms underlying these effects in breast cancer are not clear. Cell invasion is critical for neoplastic metastasis, and involves the degradation of the extracellular matrix by matrix metalloproteinase (MMP)-9. The present study investigated the inhibitory effect of DHA on MMP-9 expression and cell invasion induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in the MCF-7 breast cancer cell line. DHA inhibited the TPA-induced activation of mitogen-activated protein kinase (MAPK) and the transcription of nuclear factor (NF)-κB, but did not inhibit the transcription of activator protein-1. DHA increased the activity of peroxisome proliferator-activated receptor (PPAR)-γ, an effect that was reversed by the application of the PPAR-γ antagonist GW9662. In addition, combined treatment with GW9662 and DHA increased NF-κB-related protein expression. These results indicate that DHA regulates MMP-9 expression and cell invasion via modulation of the MAPK signaling pathway and PPAR-γ/NF-κB activity. This suggests that DHA could be a potential therapeutic agent for the prevention of breast cancer metastasis.

Aurora kinases are essential for PKC-induced invasion and matrix metalloproteinase-9 expression in MCF-7 breast cancer cells

The Aurora kinase family of serine/threonine kinases are known to be crucial for cell cycle control. Aurora kinases are considered a target of anticancer drugs. However, few studies have assessed the effect of Aurora kinases in breast cancer. In the present study, to determine whether Aurora kinases play a role in oncogenic actions of protein kinase C (PKC), we investigated the effect of Aurora kinases on PKC-induced invasion and MMP-9 expression using breast cancer cells. Treatment of MCF-7 cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) induced the upregulation and phosphorylation of Aurora kinases via the MAPK signaling pathway. Moreover, the inhibition of Aurora kinases by their siRNAs and inhibitors suppressed TPA-induced cell invasion and expression of MMP-9 by inhibiting the activation of NF-κB/AP-1, major transcription factors for MMP-9 expression in MCF-7 cells. These results suggested that Aurora kinases mediate PKC-MAPK signal to NF-κB/AP-1 with increasing MMP-9 expression and invasion of MCF-7 cells. To the best of our knowledge, this is the first study to show that Aurora kinases are key molecules in PKC-induced invasion in breast cancer cells.