Silencing of the IKKε gene by siRNA inhibits invasiveness and growth of breast cancer cells

Introduction  

IκB kinase ε (IKKε) is a member of the IKK family that plays an important role in the activation of NF-κB. Overexpressed in more than 30% of breast cancers, IKKε has been recently identified as a potential breast cancer oncogene. The purpose of the present study is to examine the therapeutic potential of IKKε siRNA on human breast cancer cells.     

Silencing of IKKε using siRNA inhibits proliferation and invasion of glioma cells in vitro and in vivo

Recent studies implicated IKKε in the pathogenesis of many human cancers by promoting cell proliferation, increasing tumor angiogenesis and metastasis, and generating resistance to cell apoptosis. However, whether IKKε can influence the invasive ability and proliferation of glioma cells remains largely unknown. In this study, we showed that overexpression of IKKε is positively correlated to glioma pathological grade, suggesting that IKKε plays a role in tumor progression, rather than tumor initiation. Targeted knockdown of IKKε in human glioma cells using siRNA, was associated with inhibition of cell growth, cell cycle arrest and decreased cell invasion; however, notable apoptosis was not observed. Furthermore, we demonstrated that transposition of NF-κB p65 resulted in the alteration of these phenotypes. Tumor growth was attenuated in established subcutaneous gliomas in nude mice treated with IKKε siRNA in vivo. Collectively, our results suggest that deregulation of IKKε plays a pivotal role in the uncontrolled proliferation and malignant invasion of glioma cells in vitro and in vivo by targeting NF-κB. Silencing of IKKε using synthetic siRNAs may offer a novel therapeutic strategy for the treatment of glioma.     

Estrogen and antiestrogens alter breast cancer invasiveness by modulating the transforming growth factor-β signaling pathway

In the later stages of breast cancer, estrogen receptor (ER)α-negative cancers typically have higher histological grades than ERα-positive cancers, and transforming growth factor (TGF)-β promotes invasion and metastasis. Our previous study indicated that ERα inhibited TGF-β signaling by inducing the degradation of Smad in an estrogen-dependent manner. In the present study, we report that the suppressive effects of ERα and estrogen on tumor progression are mediated by inhibiting TGF-β signaling. Furthermore, we investigated the effects of antiestrogens such as ICI182,780 (ICI) or tamoxifen (TAM) on TGF-β signaling and breast cancer invasiveness. The levels of total Smad and pSmad were reduced by estrogen, whereas ICI slightly increased them, and TAM had no effect. To investigate the effect of antiestrogens on breast cancer invasiveness, we generated highly migratory and invasive MCF-7-M5 cells. The migration and invasion of these cells were suppressed by the inhibitor of TGF-β receptor kinase, SB-505124, and estrogen. However, antiestrogens did not suppress the migration and invasion of these cells. In addition, we screened TGF-β target genes whose expression was reduced by estrogen treatment and identified four genes associated with breast cancer invasiveness and poor prognosis. The expression of these genes was not decreased by antiestrogens. These observations provide a new insight into estrogen function and the mechanisms underlying estrogen-mediated suppression of tumor progression.     

Celastrol inhibits the growth of estrogen positive human breast cancer cells through modulation of estrogen receptor α

We studied the chemopreventive efficacy of indole-3-carbinol (I3C), a phytochemical found in cruciferous vegetables, to inhibit tobacco carcinogen-induced lung adenocarcinoma in A/J mice when given following post-initiation or progression protocol. Moreover, we assessed the potential mechanisms responsible for the anticancer effects of I3C. Post-initiation administration of I3C decreased the multiplicity of surface tumors as well as all forms of histopathological lesions, including adenocarcinoma, whereas administration of the compound during tumor progression failed to decrease the multiplicity of surface tumors and early forms of microscopic lesions but reduced the frequency of adenocarcinoma. Mechanistic studies in A549 lung adenocarcinoma cells indicated that the lung cancer preventive effects of I3C are mediated, at least in part, via modulation of the receptor tyrosine kinase/PI3K/Akt signaling pathway.     

LncRNA PlncRNA-1 overexpression inhibits the growth of breast cancer by upregulating TGF-β1 and downregulating PHGDH

Objective

To investigate the role of lncRNA PlncRNA-1 in the pathogenesis of breast cancer.

Methods

A total of 78 patients with breast cancer as well as 48 healthy females were included in this study. Expression in tumor tissues and adjacent healthy tissues of breast cancer patients, as well as in breast tissues and serum of both patients and healthy control was detected by qRT-PCR. Cell proliferation was detected by CCK-8 assay, and cell apoptosis was tested by MTT assay. PlncRNA-1 overexpression cell lines were constructed and the effects on TGF-β1 as well as phosphoglycerate dehydrogenase (PHGDH) were explored by western blot.

Results

Expression levels of PlncRNA-1 were significantly lower in tumor tissues than those in adjacent healthy tissues. Significantly lower expression levels of PlncRNA-1 were also found in breast cancer patients than those in healthy controls in both breast tissue and serum. Upregulation of PlncRNA-1 promoted the expression of TGF-β1, but inhibited the expression of PHGDH. LncRNA PlncRNA-1 overexpression reduced the proliferation rate, but increased the apoptosis rate of breast cancer cells, while treatment with TGF-β inhibitor reduced those effects of PlncRNA-1 overexpression.

Conclusion

LncRNA PlncRNA-1 overexpression inhibits the growth of breast cancer by upregulating TGF-β1 and downregulating PHGDH.

     

Transient over-expression of estrogen receptor-�� in breast cancer cells promotes cell survival and estrogen-independent growth

Estrogen receptor-?? (ER??) positive breast cancer frequently responds to inhibitors of ER?? activity, such as tamoxifen, and/or to aromatase inhibitors that block estrogen biosynthesis. However, many patients become resistant to these agents through mechanisms that remain unclear. Previous studies have shown that expression of ER?? in ER??-negative breast cancer cell lines frequently inhibits their growth. In order to determine the consequence of ER?? over-expression in ER??-positive breast cancer cells, we over-expressed ER?? in the MCF-7 breast cancer cell line using adenovirus gene transduction. ER?? over-expression led to ligand-independent expression of the estrogen-regulated genes pS2 and PR and growth in the absence of estrogen. Interestingly, prolonged culturing of these cells in estrogen-free conditions led to the outgrowth of cells capable of growth in cultures from ER?? transduced, but not in control cultures. From these cultures a line, MLET5, was established which remained ER??-positive, but grew in an estrogen-independent manner. Moreover, MLET5 cells were inhibited by anti-estrogens showing that ER?? remains important for their growth. Gene expression microarray analysis comparing MCF-7 cells with MLET5 highlighted apoptosis as a major functional grouping that is altered in MLET5 cells, such that cell survival would be favoured. This conclusion was further substantiated by the demonstration that MLET5 show resistance to etoposide-induced apoptosis. As the gene expression microarray analysis also shows that the apoptosis gene set differentially expressed in MLET5 is enriched for estrogen-regulated genes, our findings suggest that transient over-expression of ER?? could lead to increased cell survival and the development of estrogen-independent growth, thereby contributing to resistance to endocrine therapies in breast cancer patients.     

Acidosis promotes invasiveness of breast cancer cells through ROS-AKT-NF-κB pathway

It is well known that acidic microenvironment promotes tumorigenesis, however, the underlying mechanism remains largely unknown. In the present study, we show that acidosis promotes invasiveness of breast cancer cells through a series of signaling events. First, our study indicates that NF-κB is a key factor for acidosis-induced cell invasion. Acidosis activates NF-κB without affecting STAT3 activity; knockdown of NF-κB p65 abrogates the acidosis-induced invasion activity. Next, we show that the activation of NF-κB is mediated through phosphorylation and degradation of IκBα; and phosphorylation and nuclear translocation of p65. Upstream to NF-κB signaling, AKT is activated under acidic conditions. Moreover, acidosis induces generation of reactive oxygen species (ROS) which can be suppressed by ROS scavengers, reversing the acidosis-induced activation of AKT and NF-κB, and invasiveness. As a negative regulator of AKT, PTEN is oxidized and inactivated by the acidosis-induced ROS. Finally, inhibition of NADPH oxidase (NOX) suppresses acidosis-induced ROS production, suggesting involvement of NOX in acidosis-induced signaling cascade. Of considerable interest, acidosis-induced ROS production and activation of AKT and NF-κB can be only detected in cancer cells, but not in non-malignant cells. Together, these results demonstrate a cancer specific acidosis-induced signaling cascade in breast cancer cells, leading to cell invasion.     

Expression of TGF-β1 and the mechanism of invasiveness and metastasis induced by TGF-β1 in breast cancer

Objective To investigate the expression of MMP-2,TIMP-2,TGF-β1 and TGF-βRI and the relationship among them in breast cancer.Methods The protein expression of MMP-2,TIMP-2,TGF-β1 and TGF-β1R1 was detected on tissue chips by S-P immunohistochemical staining in 160 cases of breast carcinoma.Results The positive rates of TGF-β1,TGF-β1 mRNA,MMP-2,MMP-9,TIMP-1 and TIMP-2 expression were 73.7%,56.2%,96.9%,95.0%,87.5% and 89.4%,respectively.Axillary lymph node metastasis and TNM staging(P ＜0.01 and P ＜0.01,respectively)were positively correlated to the expression of TGF-β1.Relase-free survival of TGF-β1 positive group was lower than that of TGF-β1 negative group(P = 0.023).The expression of M MP-2 or M M P-9 was positively correlated to that of TGF-β1 (r=0.170,P＜0.05;r =0.221,P＜0.01)and was negatively correlated to that of TGF-β1 mRNA(r =-0.126,P ＞0.05;r = 0.019,P ＞ 0.05).Conclusion The expression of TGF-β1 may be closely correlated with the invasion and metastasis of breast cancer.TGF-β1-induced invasiveness and metastasis of breast cancer cells are mediated by MMP-2 and MMP-9.     

Oxymatrine diminishes the side population and inhibits the expression of β-catenin in MCF-7 breast cancer cells

Cancer stem cells (CSCs) play a critical role in both cancer initiation and relapse as they are resistant to most cytotoxic agents and able to proliferate indefinitely. The plant alkaloid oxymatrine has many biological activities including the ability to induce cell cycle arrest and apoptosis, which makes it a potentially useful agent for targeting cancer cells. In order to determine whether it has beneficial pharmacological properties to eradicate CSCs, we analyzed the effects of oxymatrine on MCF-7 breast cancer cells. Cancer stem-like cells’ (side population, SP) identification and sorting were performed. The inhibitory effect of oxymatrine was evaluated on the sorted SP and non-SP cells. The results indicated that oxymatrine caused a dose-dependent reduction in the proliferation of MCF-7 cells and a decrease in SP cells. Wnt/β-catenin signaling pathway was also examined by analyzing the expression of total β-catenin and phosphorylated β-catenin in cytoplasm, and the results showed that the growth inhibitory effects of oxymatrine treatment on MCF-7 cells may be due to the inhibition of SP and Wnt/β-catenin signaling pathway. Further work is warranted to explore whether oxymatrine may be a useful novel therapeutic drug for targeting breast CSCs.

     

Oxymatrine diminishes the side population and inhibits the expression of β-catenin in MCF-7 breast cancer cells

Cancer stem cells (CSCs) play a critical role in both cancer initiation and relapse as they are resistant to most cytotoxic agents and able to proliferate indefinitely. The plant alkaloid oxymatrine has many biological activities including the ability to induce cell cycle arrest and apoptosis, which makes it a potentially useful agent for targeting cancer cells. In order to determine whether it has beneficial pharmacological properties to eradicate CSCs, we analyzed the effects of oxymatrine on MCF-7 breast cancer cells. Cancer stem-like cells' (side population, SP) identification and sorting were performed. The inhibitory effect of oxymatrine was evaluated on the sorted SP and non-SP cells. The results indicated that oxymatrine caused a dose-dependent reduction in the proliferation of MCF-7 cells and a decrease in SP cells. Wnt/β-catenin signaling pathway was also examined by analyzing the expression of total β-catenin and phosphorylated β-catenin in cytoplasm, and the results showed that the growth inhibitory effects of oxymatrine treatment on MCF-7 cells may be due to the inhibition of SP and Wnt/β-catenin signaling pathway. Further work is warranted to explore whether oxymatrine may be a useful novel therapeutic drug for targeting breast CSCs.     

Oxymatrine diminishes the side population and inhibits the expression of β-catenin in MCF-7 breast cancer cells

Cancer stem cells (CSCs) play a critical role in both cancer initiation and relapse as they are resistant to most cytotoxic agents and able to proliferate indefinitely. The plant alkaloid oxymatrine has many biological activities including the ability to induce cell cycle arrest and apoptosis, which makes it a potentially useful agent for targeting cancer cells. In order to determine whether it has beneficial pharmacological properties to eradicate CSCs, we analyzed the effects of oxymatrine on MCF-7 breast cancer cells. Cancer stem-like cells’ (side population, SP) identification and sorting were performed. The inhibitory effect of oxymatrine was evaluated on the sorted SP and non-SP cells. The results indicated that oxymatrine caused a dose-dependent reduction in the proliferation of MCF-7 cells and a decrease in SP cells. Wnt/β-catenin signaling pathway was also examined by analyzing the expression of total β-catenin and phosphorylated β-catenin in cytoplasm, and the results showed that the growth inhibitory effects of oxymatrine treatment on MCF-7 cells may be due to the inhibition of SP and Wnt/β-catenin signaling pathway. Further work is warranted to explore whether oxymatrine may be a useful novel therapeutic drug for targeting breast CSCs.     

All-trans-retinoic acid inhibits growth of head and neck cancer stem cells by suppression of Wnt/β-catenin pathway

Differentiation therapy is a novel approach to eradicate cancer stem cells (CSCs), including head and neck squamous carcinoma CSC (HNSC CSC). All-trans-retinoic acid (ATRA) is a potent differentiating agent. We studied the anti-tumour effect of ATRA on HNSC CSC. HNSC CSCs were differentiated by ATRA in a serum-free conditioned medium. The effect of differentiation on tumour growth was assessed in vitro and in vivo, and chemosensitisation was examined using a colorimetric viability assay. In addition, the involvement of Wnt/β-catenin signalling as an underlying mechanism of the anti-tumour effect of retinoic acid (RA) on HNSC CSCs was assessed. ATRA suppressed the expression of the stem cell markers Oct4, Sox2, Nestin and CD44 in HNSC CSCs and inhibited the proliferation of HNSC CSCs in vitro and in vivo. Furthermore, ATRA treatment augmented the chemosensitising effects of cisplatin. The anti-tumour effects of ATRA may be associated with down-regulation of Wnt/β-catenin signalling. In conclusion, ATRA may be potentially valuable in treatment of HNSC CSC, especially in combination with cisplatin.     

Combination of microwave hyperthermia with epirubicin inhibits the proliferation and induces the apoptosis of breast cancer cells北大核心CSCD

Objective: To investigate the effects of microwave hyperthermia in combination with epirubicin on the growth of orthotopic breast transplantation tumor in BALB/c mice and the proliferation of murine breast cancer 4T1 cells and human breast cancer MDA-MB-231 cells, and to explore their possible mechanisms. Methods: The 4T1 cells were injected into mammary fat pad of female BALB/c mice to establish the orthotopic breast transplantation tumor model. The tumor-bearing mice were treated with microwave hyperthermia, epirubicin and microwave hyperthermia in combination with epirubicin, respectively. The breast tumor volume and weight and the number of lung metastatic nodes in mice were observed. The 4T1 and MDA-MB-231 cells were treated with microwave hyperthermia, epirubicin and microwave hyperthermia in combination with epirubicin, respectively. Then the cell proliferation and apoptosis were detected by MTS assay and FCM method, respectively. The change of phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway and the expressions of apoptosis-related proteins were detected by Western blotting. Results: The tumor volume (P < 0.05) and weight (P < 0.05)and the number of lung metastatic nodes (P < 0.01) in mice in microwave hyperthermia in combination with epirubicin group were all smaller than those in the control group (the tumor-bearing mice didn't receive any treatment). The proliferation of breast cancer 4T1 and MDA-MB-231 cells in microwave hyperthermia in combination with epirubicin group was inhibited and the apoptosis was induced (all P < 0.05). Combination of epirubicin with microwave hyperthermia suppressed the activation of mTOR in 4T1 and MDA-MB-231 cells (both P < 0.05) and up-regulated the expressions of apoptosis-related proteins (all P < 0.05). Conclusion: Combination of microwave hyperthermia with epirubicin can suppress the growth and metastasis of breast cancer. This effect may be associated with the down-regulation of mTOR pathway and the up-regulation of apoptosis-related protein expressions. Copyright © 2018 by TUMOR. All rights reserved.     

Peroxiredoxin 2 knockdown by RNA interference inhibits the growth of colorectal cancer cells by downregulating Wnt/β-catenin signaling

Peroxiredoxin 2 (Prdx2) has been shown to act as an antioxidant whose main function is to reduce hydrogen peroxide (H₂O₂) in cells, and Prdx2 is abnormally elevated in colorectal cancer (CRC). However, the functional significance of this up-regulation and the detailed molecular mechanism behind the regulatory effect of Prdx2 on the growth of CRC cells have not been elucidated. In this study, we demonstrated that Prdx2 knockdown using a lentiviral vector-mediated specific shRNA inhibited cell growth, stimulated apoptosis, and augmented the production of endogenous reactive oxygen species (ROS). Further, silencing of Prdx2 resulted in an altered expression of proteins associated with the Wnt signaling pathway. Finally, Prdx2 knockdown contributed to attenuated CRC growth in BALB/c nude mice. In conclusion, these findings demonstrate that the regulatory effects of Prdx2 can be partially attributed to Wnt/β-catenin signaling.     

Silencing of Src by siRNA inhibits laryngeal carcinoma growth through the Src/PI-3 K/Akt pathway in vitro and in vivo

This study aimed to investigate the expression, function, and possible mechanism of Src in the Hep-2 cell line. We used Src-specific small interfering RNA (siRNA) to inhibit the expression of Src in Hep-2 cells. RT-PCR and Western blot were applied to evaluate the expression level of Src after RNA interference, and the MTT assay and flow cytometry were used to observe the expression of PI-3 K and Akt. siRNA can downregulate the expression of Src in Hep-2 cells. Downregulation of Src decreased PI-3 K and Akt expression. We found that Src knockdown inhibits the proliferation of Hep-2 cells and the growth of laryngeal carcinoma in vivo. This study has demonstrated that Src participates in the regulation of apoptosis through the Src/PI-3 K/Akt signaling pathway in the Hep-2 cell line. Silencing of Src by siRNA is a viable approach in laryngeal carcinoma treatment.     

Combinatorial TGF-β attenuation with paclitaxel inhibits the epithelial-to-mesenchymal transition and breast cancer stem-like cells

Distant relapse after chemotherapy is an important clinical issue for treating breast cancer patients and results from the development of cancer stem-like cells (CSCs) during chemotherapy. Here we report that blocking epithelial-to-mesenchymal transition (EMT) suppresses paclitaxel-induced CSCs properties by using a MDA-MB-231-xenografted mice model (in vivo), and breast cancer cell lines (in vitro). Paclitaxel, one of the cytotoxic taxane-drugs such as docetaxel, increases mesenchymal markers (Vimentin and Fibronectin) and decreases an epithelial marker (Zo-1). Blocking TGF-β signaling with the TGF-β type I receptor kinase (ALK5) inhibitor, EW-7197, suppresses paclitaxel-induced EMT and CSC properties such as mammosphere-forming efficiency (MSFE), aldehyde dehydrogenase (ALDH) activity, CD44⁺/CD24⁻ ratio, and pluripotency regulators (Oct4, Nanog, Klf4, Myc, and Sox2). The combinatorial treatment of EW-7197 improves the therapeutic effect of paclitaxel by decreasing the lung metastasis and increasing the survival time in vivo. We confirmed that Snail is increased by paclitaxel-induced intracellular reactive oxygen species (ROS) and EW-7197 suppresses the paclitaxel-induced Snail and EMT by attenuating paclitaxel-induced intracellular ROS. Knock-down of SNAI1 suppresses paclitaxel-induced EMT and CSC properties. These data together suggest that blocking the Snail-induced EMT with the ALK5 inhibitor attenuates metastasis after paclitaxel-therapy and that this combinatorial approach could prove useful in treating breast cancer.