Exploration of drug resistance mechanisms in triple negative breast cancer cells using a microfluidic device and patient tissues.

Chemoresistance is a major cause of treatment failure in many cancers. However, the life cycle of cancer cells as they respond to and survive environmental and therapeutic stress is understudied. In this study, we utilized a microfluidic device to induce the development of doxorubicin-resistant (DOXR) cells from triple negative breast cancer (TNBC) cells within 11 days by generating gradients of DOX and medium. In vivo chemoresistant xenograft models, an unbiased genome-wide transcriptome analysis, and a patient data/tissue analysis all showed that chemoresistance arose from failed epigenetic control of the nuclear protein-1 (NUPR1)/histone deacetylase 11 (HDAC11) axis, and high NUPR1 expression correlated with poor clinical outcomes. These results suggest that the chip can rapidly induce resistant cells that increase tumor heterogeneity and chemoresistance, highlighting the need for further studies on the epigenetic control of the NUPR1/HDAC11 axis in TNBC.

Effective decellularization of human skin tissue for regenerative medicine by supercritical carbon dioxide technique.

Allotransplantation, performed using an acellular dermal matrix (ADM), plays a significant role in the cultivation of constituted and damaged organs in clinical. Herein, we fabricated an innovative ADM for allografting derived from decellularized human skin by utilizing the supercritical fluid of carbon dioxide to eliminate immunogenic components. By using histological staining, the ADM product demonstrated the successful removal of cellular constituents without exerting any harmful influence on the extracellular matrix. The results from DNA electrophoresis also supported this phenomenon by showing the complete DNA removal in the product, accompanied by the absence of Major Histocompatibility Complex 1, which suggested the supercritical fluid is an effective method for cellular withdrawal. Moreover, the mechanical property of the ADM products, which showed similarity to that of native skin, displayed great compatibility for using our human-derived ADM as an allograft in clinical treatment. Specifically, the cell viability demonstrated the remarkable biocompatibility of the product to human bio-cellular environment which was noticeably higher than that of other products. Additionally, the significant increase in the level of growth factors such as vascular endothelial growth factor, urokinase-type plasminogen activator receptor, granulocyte-macrophage colony-stimulating factor suggested the ability to stimulate cellular processes, proving the products to be innovative in the field of regeneration when applied to clinical in the future. This study provides a thoroughly extensive analysis of the new ADM products, enabling them to be applied in industrial and clinical treatment.

The Effectiveness and safety of T-MSAT on inpatients with acute low back pain caused by traffic accidents: A protocol for randomized controlled trial.

BACKGROUND: Presentation of musculoskeletal symptoms, such as pain, discomfort, or disability, caused by a traffic accident (TA) is a common occurrence. However, studies on treatment and management of sudden low back pain (LBP) caused by a TA are very scarce, while studies on the effectiveness of motion style acupuncture therapy (MSAT) used on such patients are also rare. Accordingly, a randomized controlled trial (RCT) is planned to assess the effectiveness and safety of MSAT using traction (T-MSAT) for the treatment of pain and functional problems in patients with acute LBP caused by a TA. METHODS: This study will be conducted at Jaseng Hospital of Korean Medicine in South Korea, using a two-armed, parallel, assessor-blinded RCT design. The study population will consist of 100 participants who will be randomly assigned in a 1:1 ratio to either the T-MSAT+integrative Korean medicine therapy (IKMT) group or IKMT control group. The treatment will be applied continuously for 3 days after admission. The primary outcome will be the difference between the numeric rating scale (NRS) scores at admission and immediately after treatment on the fourth day of admission. Secondary outcomes will include visual analogue scale (VAS) for LBP and radiating leg pain; NRS for radiating leg pain; lumbar active range of motion; Oswestry Disability Index (ODI); Patient Global Impression of Change (PGIC); the Post-traumatic Stress Disorder Checklist for DSM-5 (PCL-5-K); and 12-item short-form health survey (SF-12). DISCUSSION: This study is a RCT to assess the effectiveness and safety of T-MSAT for acute LBP caused by a TA. The findings could be used by healthcare-related policy makers and clinicians in primary care institutions, which are frequently visited by patients suffering from LBP caused by a TA.

Manipulation of light transmission from stable magnetic microrods formed by the alignment of magnetic nanoparticles.

Due to the increasing energy consumption, smart technologies have been considered to automatically control energy loss. Smart windows, which can use external signals to modulate their transparency, can regulate solar energy by reflecting excess energy and retaining the required energy in a building without using additional energy to cool or heat the interiors of the building. Although many technologies have been developed for smart windows, they still need to be economically optimised. Here, we propose a facile method to synthesise magnetic microrods from magnetic nanoparticles by alignment using a magnetic field. To maximise the transparency difference in the ON and OFF states, we controlled the nanoparticle concentration in a dispersion liquid, magnetic field application time, and viscosity of the dispersant. Interestingly, the magnetic microrods remained stable when we mixed short-chain polymers (polyethylene glycol) with a liquid dispersant (isopropyl alcohol). Furthermore, the Fe2O3 microrods maintained their shape for more than a week, while the Fe3O4 microrods clustered after a day because they became permanent magnets. The anisotropic features of the magnetic rods were used as a light valve to control the transparency of the smart window.

Chemoresistance in the Human Triple-Negative Breast Cancer Cell Line MDA-MB-231 Induced by Doxorubicin Gradient Is Associated with Epigenetic Alterations in Histone Deacetylase.

Chemoresistance is one of the major causes of therapeutic failure in breast cancer patients. In this study, the mechanism of chemoresistance in human triple-negative breast cancer (TNBC) cells (MDA-MB-231) induced by doxorubicin (DOX) gradient was investigated. These DOX-resistant cells showed higher drug efflux rate, increased anchorage-independent growth when cultured in suspension, and increased tumor-forming ability in nude mice, compared to the wild-type MDA-MB-231 cells. RNA sequencing analysis showed an increase in the expression of genes involved in membrane transport, antiapoptosis, and histone regulation. Kaplan-Meier plot analysis of TNBC patients who underwent preoperative chemotherapy showed that the relapse free survival (RFS) of patients with high HIST1H2BK (histone cluster 1 H2B family member k) expression was significantly lower than that of patients with low HIST1H2BK expression. Quantitative real-time PCR confirmed that the level of HIST1H2BK expression was increased in resistant cells. The cytotoxicity analysis showed that the DOX resistance of resistant cells was reduced by treatment with a histone deacetylase (HDAC) inhibitor. Our results suggest that, in DOX-resistant cells, HIST1H2BK expression can be rapidly induced by the high expression of genes involved in membrane transport, antiapoptosis, and histone regulation. In conclusion, chemoresistance in MDA-MB-231 cells can occur in a relatively short period by DOX gradient via this previously known mechanism of resistance, and DOX resistance is dependent on the specificity of resistant cells to HDAC.

Formation of size-controllable tumour spheroids using a microfluidic pillar array (µFPA) device.

Spheroids are recognized for replicating the physiological microenvironment of tumours. However, because of the lack of controllability of the spheroid size, the response to anticancer drugs is variable in conventional spheroid culture methods. In this paper, we describe a method to generate several hundreds of spheroids of various types of cancer cells including patient derived cancer cells (PDCs) using a microfluidic device with pillars (diameter: 40 µm, height: 70 µm, center-to-center distance: 140 µm), called a microfluidic pillar array (µFPA) device. About three hundred glioma (U87) spheroids were obtained in the µFPA device within 3 days, and about 90% of them ranged from 175 to 225 µm. These spheroids were more resistant to doxorubicin at 10 µM than U87 cells in a monolayer. The former showed higher expression of CD133, a cancer stem cell marker, than the latter. Hypoxia inducible factor-1α (HIF-1α), another cancer stem cell marker, was found in the nucleus of the former, but found in the cytoplasm of the cells in a monolayer. Drug responses of spheroids of another glioma cell line (U251) and triple negative breast cancer (TNBC) primary cells were also easily quantified by measuring changes in spheroid size at different concentrations of their respective drug on the µFPA device. The µFPA device can be a powerful platform for obtaining uniform spheroids and monitoring the drug response of cancer cells including PDCs.

Microfluidic gut-on-a-chip with three-dimensional villi structure.

Current in vitro gut models lack physiological relevance, and various approaches have been taken to improve current cell culture models. For example, mimicking the three-dimensional (3D) tissue structure or fluidic environment has been shown to improve the physiological function of gut cells. Here, we incorporated a collagen scaffold that mimics the human intestinal villi into a microfluidic device, thus providing cells with both 3D tissue structure and fluidic shear. We hypothesized that the combined effect of 3D structure and fluidic shear may provide cells with adequate stimulus to induce further differentiation and improve physiological relevance. The physiological function of our '3D gut chip' was assessed by measuring the absorptive permeability of the gut epithelium and activity of representative enzymes, as well as morphological evaluation. Our results suggest that the combination of fluidic stimulus and 3D structure induces further improvement in gut functions. Our work provides insight into the effect of different tissue environment on gut cells.

Rapid emergence and mechanisms of resistance by U87 glioblastoma cells to doxorubicin in an in vitro tumor microfluidic ecology.

In vitro prediction of the probable rapid emergence of resistance to a drug in tumors could act to winnow out potential candidates for further costly development. We have developed a microfluidic device consisting of ∼500 hexagonal microcompartments that provides a complex ecology with wide ranges of drug and nutrient gradients and local populations. This ecology of a fragmented metapopulation induced the drug resistance in stage IV U87 glioblastoma cells to doxorubicin in 7 d. Exome and transcriptome sequencing of the resistant cells identified mutations and differentially expressed genes. Gene ontology and pathway analyses of the genes identified showed that they were functionally relevant to the established mechanisms of doxorubicin action. Specifically, we identified (i) a frame-shift insertion in the filamin-A gene, which regulates the influx and efflux of topoisomerase II poisons; (ii) the overexpression of aldo-keto reductase enzymes, which convert doxorubicin into doxorubicinol; and (iii) activation of NF-κB via alterations in the nucleotide-binding oligomerization domain (NOD)-like receptor signaling pathway from mutations in three genes (CARD6, NSD1, and NLRP13) and the overexpression of inflammatory cytokines. Functional experiments support the in silico analyses and, together, demonstrate the effects of these genetic changes. Our findings suggest that, given the rapid evolution of resistance and the focused response, this technology could act as a rapid screening modality for genetic aberrations leading to resistance to chemotherapy as well as counter selection of drugs unlikely to be successful ultimately.

Elevated IL-1ß expression induces invasiveness of triple negative breast cancer cells and is suppressed by zerumbone.

Aberrant interleukin-1 beta (IL-1ß) expression is associated with cancer development, metastasis, and poor prognosis. Here, we have investigated the regulatory mechanism of IL-1ß expression, and the inhibitory effect of zerumbone (ZER) on IL-1ß expression and IL-1ß-induced signatures, including cell invasion and signaling activation in triple negative breast cancer (TNBC) cells. The basal IL-1ß and cell invasiveness levels were significantly higher in TNBC cells, compared with non-TNBC cells. The invasiveness of TNBC cells was also increased following IL-1ß treatment. In contrast, the invasiveness of TNBC cells was decreased following IL-1 receptor antagonist (IL-1RA) treatment. Additionally, the basal IL-1ß level and the invasiveness of TNBC cells were decreased by Bay11-7085. In contrast, overexpression of NF-κB (p65) caused an increase in IL-1ß expression in TNBC cells. Our results showed that treatment with ZER decreased the basal IL-1ß expression level, and the phosphorylation level of NF-κB, in TNBC cells. Furthermore, we found that ZER completely suppressed IL-1ß-induced NF-κB phosphorylation, but did not suppress IL-1ß-induced Akt phosphorylation, in TNBC cells. Our results also demonstrate that IL-1ß-induced cell invasion is suppressed by ZER in TNBC cells. Taken together, we demonstrated that IL-1ß expression is regulated by the NF-κB-dependent pathway, and that elevated IL-1ß is directly influencing the invasiveness of TNBC cells. ZER down-regulates IL-1ß expression through the inhibition of NF-κB activity, and then suppresses cell invasiveness of TNBC.

STC-1 expression is upregulated through an Akt/NF-κB-dependent pathway in triple-negative breast cancer cells.

Stanniocalcin-1 (STC-1) is a secreted glycoprotein and its expression is strongly correlated with cancer development. However, regulatory mechanism of STC-1 expression in breast cancer cells is not clear. In the present study, we investigated whether STC-1 acts as a prognostic factor in TNBC patients and the regulation of STC-1 expression in breast cancer cells. Basal levels of STC-1 were significantly higher in TNBC cells than in non-TNBC cells. Induction of STC-1 expression was also associated with poor relapse-free survival of TNBC patients. In addition, we verified the correlation between the invasiveness of TNBC cells and the STC-1 expression. We found that recombinant human STC-1 treatment increased the invasiveness of TNBC cells. In contrast, STC-1-induced cell invasiveness was completely inhibited by anti-STC-1 monoclonal antibody treatment. We found that the basal levels of STC-1 expression in TNBC cells were decreased by treatment with LY294002 or Bay11-7085, but not SB203580. In contrast, transcript levels of STC-1 and protein secretion were increased by constitutively active Akt (CA-Akt) or NF-κB overexpression in TNBC cells. Finally, we observed that phosphorylation of NF-κB was significantly increased by CA-Akt overexpression in TNBC cells. Taken together, elevated STC-1 expression is associated with poor clinical outcome in TNBC patients, and STC-1 is directly involved in the invasiveness of TNBC cells. STC-1 expression is upregulated through a PI-3K/Akt/NF-κB­dependent signaling pathway in TNBC cells.

Elevated STC­1 augments the invasiveness of triple­negative breast cancer cells through activation of the JNK/c­Jun signaling pathway.

Stanniocalcin­1 (STC­1), a secreted glycoprotein, is highly expressed in a variety of human malignancies. However, the role of STC­1 has not been fully elucidated in breast cancer cells. Here, we investigated whether STC­1 acts as a prognostic factor in triple­negative breast cancer (TNBC) patients, and we explored the cellular mechanism in breast cancer cells. The level of STC­1 expression was directly associated with the relapse­free and overall survival of basal­type breast cancer patients. Breast cancer patients with a high level of STC­1 had poor prognosis. In addition, our results showed that the level of STC­1 expression was markedly higher in TNBC than in non­TNBC cells. Invasiveness of the TNBC cells was also significantly increased in response to recombinant human STC­1 treatment. In contrast, the invaded cell numbers were completely decreased by STC­1 siRNA overexpression in the Hs578T and MDA­MB­231 TNBC cells. Our results showed that the phosphorylation of c­Jun N­terminal protein kinase (JNK) and c­Jun was increased after STC­1 treatment but not the phosphorylation of ERK and p38 MAPKs in the Hs578T and MDA­MB­231 TNBC cells. Furthermore, expression of one invasion­related gene MMP­9, was increased by STC­1 treatment. STC­1­induced MMP­9 expression was suppressed by SP600125 (a JNK inhibitor) in the Hs578T cells. STC­1­induced cell invasiveness was also inhibited by SP600125. Taken together, we demonstrated that aberrant STC­1 expression is associated with poor prognosis and stimulates the invasiveness of TNBC cells through the JNK/c­Jun­dependent signaling pathway.

Silibinin inhibits triple negative breast cancer cell motility by suppressing TGF-ß2 expression.

Transforming growth factor-beta (TGF-ß) is a multifunctional cytokine that regulates many biological events including cell motility and angiogenesis. Here, we investigated the role of elevated TGF-ß2 level in triple negative breast cancer (TNBC) cells and the inhibitory effect of silibinin on TGF-ß2 action in TNBC cells. Breast cancer patients with high TGF-ß2 expression have a poor prognosis. The levels of TGF-ß2 expression increased significantly in TNBC cells compared with those in non-TNBC cells. In addition, cell motility-related genes such as fibronectin (FN) and matrix metalloproteinase-2 (MMP-2) expression also increased in TNBC cells. Basal FN, MMP-2, and MMP-9 expression levels decreased in response to LY2109761, a dual TGF-ß receptor I/II inhibitor, in TNBC cells. TNBC cell migration also decreased in response to LY2109761. Furthermore, we observed that TGF-ß2 augmented the FN, MMP-2, and MMP-9 expression levels in a time- and dose-dependent manner. In contrast, TGF-ß2-induced FN, MMP-2, and MMP-9 expression levels decreased significantly in response to LY2109761. Interestingly, we found that silibinin decreased TGF-ß2 mRNA expression level but not that of TGF-ß1 in TNBC cells. Cell migration as well as basal FN and MMP-2 expression levels decreased in response to silibinin. Furthermore, silibinin significantly decreased TGF-ß2-induced FN, MMP-2, and MMP-9 expression levels and suppressed the lung metastasis of TNBC cells. Taken together, these results suggest that silibinin suppresses metastatic potential of TNBC cells by inhibiting TGF-ß2 expression in TNBC cells. Thus, silibinin may be a promising therapeutic drug to treat TNBC.

Zerumbone suppresses EGF-induced CD44 expression through the inhibition of STAT3 in breast cancer cells.

Expression of the CD44 gene is upregulated in breast cancer cells and is correlated with patient survival. Aberrant CD44 expression promotes tumor progression and metastasis. In the present study, we investigated the role of zerumbone (ZER) on regulatory mechanisms of CD44 expression in breast cancer cells. Our results showed that CD44 expression was significantly increased by epidermal growth factor receptor (EGFR) ligands in SKBR3 breast cancer cells. In contrast, EGF-induced CD44 expression was decreased by a MEK1/2 inhibitor, UO126, or STAT3 inhibitor, STAT3 VI, respectively. Notably, ZER downregulated the basal level of CD44 expression in CD44+ breast cancer cells. In addition, the induction of CD44 expression by EGFR ligands, EGF or TGF-α, was markedly decreased by ZER treatment. Finally, we investigated the inhibitory mechanism of ZER on EGF-induced CD44 expression. Our results showed that EGF-induced phosphorylation of STAT3 was completely suppressed by ZER. Collectively, ZER suppressed EGF-induced CD44 expression through inhibition of the STAT3 pathway. Therefore, we suggested that ZER may act as a promising therapeutic drug for the treatment of breast cancer.

Induction of fibronectin in response to epidermal growth factor is suppressed by silibinin through the inhibition of STAT3 in triple negative breast cancer cells.

Fibronectin (FN) plays a major role in cell adhesion, migration and oncogenic transformation. Aberrant FN expression is associated with poor prognosis in various types of cancer, including breast cancer. In this study, we investigated the effect of silibinin on the epidermal growth factor (EGF)-induced FN expression in triple negative breast cancer (TNBC) cells. Our data showed that the levels of FN mRNA and protein expression were dose-dependently increased by EGF in MDA-MB468 and BT20 breast cancer cells. Consequently, EGF-induced FN expression was decreased by the epidermal growth factor receptor (EGFR) inhibitors AG1478 and gefitinib. EGF-induced FN expression was also decreased by MEK1/2, PI3K and STAT3 specific inhibitors. In the present study, we observed for the first time that EGF-induced FN expression was significantly decreased by silibinin treatment in TNBC cells. Furthermore, we found that silibinin suppressed the EGF-induced phosphorylation of STAT3 but not Erk and Akt. Taken together, silibinin downregulated EGF-induced FN expression through the inhibition of STAT3 phosphorylation in TNBC cells. Silibinin may be a promising anticancer drug for the treatment of TNBC.

Zerumbone suppresses IL-1ß-induced cell migration and invasion by inhibiting IL-8 and MMP-3 expression in human triple-negative breast cancer cells.

Inflammation is a key regulatory process in cancer development. Prolonged exposure of breast tumor cells to inflammatory cytokines leads to epithelial-mesenchymal transition, which is the principal mechanism involved in metastasis and tumor invasion. Interleukin (IL)-1ß is a major inflammatory cytokine in a variety of tumors. To date, the regulatory mechanism of IL-1ß-induced cell migration and invasion has not been fully elucidated. Here, we investigated the effect of zerumbone (ZER) on IL-1ß-induced cell migration and invasion in breast cancer cells. The levels of IL-8 and matrix metalloproteinase (MMP)-3 mRNA were analyzed by real-time polymerase chain reaction. The levels of secreted IL-8 and MMP-3 protein were analyzed by enzyme-linked immunosorbent assay and western blot analysis, respectively. Cell invasion and migration was detected by Boyden chamber assay. The levels of IL-8 and MMP-3 expression were significantly increased by IL-1ß treatment in Hs578T and MDA-MB231 cells. On the other hand, IL-1ß-induced IL-8 and MMP-3 expression was decreased by ZER. Finally, IL-1ß-induced cell migration and invasion were decreased by ZER in Hs578T and MDA-MB231 cells. ZER suppresses IL-1ß-induced cell migration and invasion by inhibiting IL-8 expression and MMP-3 expression in TNBC cells. ZER could be a promising therapeutic drug for treatment of triple-negative breast cancer patients.

Berberine suppresses TPA-induced fibronectin expression through the inhibition of VEGF secretion in breast cancer cells.

BACKGROUND/AIMS: Berberine (BBR) is an isoquinoline alkaloid and is beneficial for the anticancer effect on a variety of human tumor cells. However, BBR's anti-angiogenesis property and its clinical potential as an inhibitor of tumor angiogenesis in breast cancer cells have not been fully elucidated. Here, we investigated the effect of BBR on TPA-induced VEGF and fibronectin (FN) as well as VEGF-induced FN in breast cancer cells. METHODS: The secretion of VEGF protein was detected by ELISA. Fibronectin mRNA and protein expression was analyzed by Real-Time PCR and western blotting, respectively. The overexpressions of CA-MEK, and CA-Akt were examined by adenovirus system. RESULTS: Our results showed that TPA, a tumor promoter, significantly increased the level of VEGF and FN expression in both MCF7 and T47D breast cancer cells. On the other hand, TPA-induced VEGF and FN expression was suppressed by LY294002, a PI-3K inhibitor. In contrast, the level of FN expression also significantly increased by constitutively active (CA)-AKT overexpression. We also found that TPA-induced VEGF and FN expression was decreased by BBR treatment. Finally, our results showed that VEGF augmented the expression of FN whereas VEGF-induced FN expression was decreased by BBR treatment. CONCLUSION: Taken together, we suggest that BBR may suppress TPA-induced VEGF and FN as well as VEGF-induced FN through the inhibition of the PI-3K/AKT pathway in breast cancer cells. Therefore, we suggest that BBR may be used as a candidate drug for the inhibition of angiogenesis of human breast cancer.

Silibinin inhibits TPA-induced cell migration and MMP-9 expression in thyroid and breast cancer cells.

Matrix metalloproteinases (MMPs) play an important role in cancer metastasis, cell migration and invasion. Herein, we investigated the effects of silibinin on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell migration and MMP-9 expression in thyroid and breast cancer cells. Our results revealed that the levels of MMP-9 mRNA and protein expression were significantly increased by TPA but not MMP-2 in TPC-1 and MCF7 cells. To verify the regulatory mechanism of TPA-induced MMP-9 expression, we treated TPC-1 and MCF7 cells with the MEK1/2 inhibitor, UO126, and TPA-induced MMP-9 expression was significantly decreased. We also found that TPA-induced cell migration and MMP-9 expression was significantly decreased by silibinin. In addition, TPA-induced phosphorylation of MEK and ERK was also inhibited by silibinin. Taken together, we suggest that silibinin suppresses TPA-induced cell migration and MMP-9 expression through the MEK/ERK-dependent pathway in thyroid and breast cancer cells.

A functional comparison between the HER2(high)/HER3 and the HER2(low)/HER3 dimers on heregulin-ß1-induced MMP-1 and MMP-9 expression in breast cancer cells.

Overexpression of HER2 correlates with more aggressive tumors and increased resistance to cancer chemotherapy. However, a functional comparison between the HER2(high)/HER3 and the HER2(low)/HER3 dimers on tumor metastasis has not been conducted. Herein we examined the regulation mechanism of heregulin- ß1 (HRG)-induced MMP-1 and -9 expression in breast cancer cell lines. Our results showed that the basal levels of MMP-1 and -9 mRNA and protein expression were increased by HRG treatment. In addition, HRG-induced MMP-1 and -9 expression was significantly decreased by MEK1/2 inhibitor, U0126 but not by phosphatidylinositol 3-kinase (PI-3K) inhibitor, LY294002. To confirm the role of MEK/ERK pathway on HRG-induced MMP-1 and -9 expression, MCF7 cells were transfected with constitutively active adenoviral- MEK (CA-MEK). The level of MMP-1 and -9 expressions was increased by CA-MEK. MMP-1 and -9 mRNA and protein expressions in response to HRG were higher in HER2 overexpressed cells than in vector alone. The phosphorylation of HER2, HER3, ERK, Akt, and JNK were also significantly increased in HER2 overexpressed MCF7 cells compared with vector alone. HRG-induced MMP-1 and -9 expressions were significantly decreased by lapatinib, which inhibits HER1 and HER2 activity, in both vector alone and HER2 overexpressed MCF7 cells. Finally, HRG-induced MMP-1 and MMP-9 expression was decreased by HER3 siRNA overexpression. Taken together, we suggested that HRG-induced MMP-1 and MMP-9 expression is mediated through HER3 dependent pathway and highly expressed HER2 may be associated with more aggressive metastasis than the low expressed HER2 in breast cancer cells.

Berberine suppresses the TPA-induced MMP-1 and MMP-9 expressions through the inhibition of PKC-α in breast cancer cells.

BACKGROUND: Berberine (BBR) is one of the major alkaloids, and it has been reported to have a variety of pharmacologic effects, including inhibition of cell cycle progression. Here, we investigated the effect of BBR on the MMP-1 and MMP-9 expressions, which are predictors of metastasis and invasion in breast cancer cells. METHODS: MMP-1 and MMP-9 mRNA expressions were analyzed by real-time PCR. The levels of MMP-1 protein and PKC-α phosphorylation were detected by Western blotting. MMP-9 protein expression was detected by gelatin zymography. Cell cycle was analyzed by FACS analysis. PKC-α knock-down was examined by PKC-α siRNA transfection. RESULTS: The basal levels of both the MMP-1 and MMP-9 mRNA expressions were decreased by BBR treatment in a dose-dependent manner. In contrast, TPA, which is a tumor promoter, significantly increased the levels of the MMP-1 and MMP-9 mRNA and protein expressions in the MCF-7 breast cancer cells. We also observed that the TPA-induced MMP-1 and MMP-9 mRNA and protein expressions were prevented by BBR treatment. In addition, the TPA-induced MMP-1 and MMP-9 expressions were completely decreased by Go6983 and PKC-α siRNA, respectively. TPA-induced PKC-α phosphorylation was dose-dependently decreased by BBR treatment. CONCLUSION: The TPA-induced PKC-α phosphorylation is suppressed and then the MMP-1 and MMP-9 expressions are also inhibited by berberine. Therefore, we suggest that berberine may be used as a candidate drug for the inhibition of metastasis of human breast cancer.

TPA-induced p21 expression augments G2/M arrest through a p53-independent mechanism in human breast cancer cells.

The tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), has a differential role on the regulation of the cell cycle in a variety of tumor cells. The mechanism between TPA and the cell cycle in breast cancer is not fully understood. Therefore, we investigated the regulatory mechanism of TPA on control of the cell cycle of breast cancer cells. Our results showed that TPA increased the level of p21 expression in MCF-7 cells with wild-type p53 and MDA-MB-231 cells with mutant p53 in a dose-dependent manner. In contrast, TPA decreased the expression of p53 in MCF-7 cells, but did not affect MDA-MB-231 cells. We next examined the regulatory mechanism of TPA on p21 and p53 expression. Our results showed that the TPA-induced up-regulation of p21 and down-regulation of p53 was reversed by UO126 (a MEK1/2 inhibitor), but not by SP600125 (a JNK inhibitor) or SB203580 (a p38 inhibitor), although TPA increased the phosphorylation of ERK and JNK in MCF-7 cells. In addition, the TPA-induced arrest of the G2/M phase was also recovered by UO126 treatment. To confirm the expression of p21 through the MEK/ERK pathway, cells were transfected with constitutively active (CA)-MEK adenovirus. Our results showed that the expression of p21 was significantly increased by CA-MEK overexpression. Taken together, we suggest that TPA reciprocally regulates the level of p21 and p53 expression via a MEK/ERK-dependent pathway. The up-regulation of p21 in response to TPA is mediated through a p53-independent mechanism in breast cancer cells.