CARMA3 overexpression accelerates cell proliferation and inhibits paclitaxel-induced apoptosis through NF-κB regulation in breast cancer cells

CARMA3 was recently reported to be overexpressed in several cancers and associated with malignant behavior of cancer cells. However, the expression pattern and biological roles of CARMA3 in breast cancer have not been reported. In the present study, we found that CARMA3 was overexpressed in 41.9 % of breast cancer specimens. Significant association was observed between CARMA3 overexpression and TNM stage (p?=?0.0223), tumor size (p?=?0.0227), and ErbB-2 status (p?=?0.0049). Furthermore, knockdown of CARMA3 expression in MDA-MB-435 cells with high endogenous expression decreased cell proliferation and sensitized cell to paclitaxel-induced apoptosis, while overexpression of CARMA3 in MDA-MB-231 cell line promoted cell proliferation and inhibited apoptosis. Further analysis showed that CARMA3 depletion downregulated, and its overexpression upregulated cyclin D1, Bcl-2, and p-IκB levels. In conclusion, our study demonstrated that CARMA3 is overexpressed in breast cancers. CARMA3 facilitates proliferation and inhibits apoptosis through nuclear factor-kappaB signaling.     

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.     

Immunosuppression through constitutively activated NF-κB signalling in human ovarian cancer and its reversal by an NF-κB inhibitor

Background:

Although T-cell immunity is thought to be involved in the prognosis of epithelial ovarian cancer (EOC) patients, immunosuppressive conditions hamper antitumour immune responses. Thus, their mechanisms and overcoming strategies need to be investigated.

Methods:

The role of NF-κB in human EOC cells and macrophages was evaluated by in vitro production of immunosuppressive IL-6 and IL-8 by EOC cells and in vivo analysis of immune responses in nude mice implanted with human EOC cells using an NF-κB inhibitor DHMEQ.

Results:

In EOC patients, increased plasma IL-6, IL-8, and arginase were observed. The NF-κB inhibitor DHMEQ inhibited the production of IL-6 and IL-8 by EOC cell lines. Immunosuppression of human DCs and macrophages by culture supernatant of EOC cells was reversed with the pretreatment of DHMEQ. Administration of DHMEQ to nude mice implanted with human EOC resulted in the restoration of T-cell stimulatory activity of murine DCs along with the reduction of tumour accumulation and arginase expression of MDSCs. Nuclear factor-κB inhibition in tumour-bearing mice also enhanced antitumour effects of transferred murine naive T cells.

Conclusions:

NF-κB is involved in the immunosuppression induced by human EOC, and its inhibitor may restore antitumour immune responses, indicating that NF-κB is an attractive target for EOC treatment.     

The semisynthetic flavonoid monoHER sensitises human soft tissue sarcoma cells to doxorubicin-induced apoptosis via inhibition of nuclear factor-κB

Background:

Despite therapeutic advances, the prognosis of patients with metastatic soft tissue sarcoma (STS) remains extremely poor. The results of a recent clinical phase II study, evaluating the protective effects of the semisynthetic flavonoid 7-mono-O-(β-hydroxyethyl)-rutoside (monoHER) on doxorubicin-induced cardiotoxicity, suggest that monoHER enhances the antitumour activity of doxorubicin in STSs.

Methods:

To molecularly explain this unexpected finding, we investigated the effect of monoHER on the cytotoxicity of doxorubicin, and the potential involvement of glutathione (GSH) depletion and nuclear factor-κB (NF-κB) inactivation in the chemosensitising effect of monoHER.

Results:

MonoHER potentiated the antitumour activity of doxorubicin in the human liposarcoma cell line WLS-160. Moreover, the combination of monoHER with doxorubicin induced more apoptosis in WLS-160 cells compared with doxorubicin alone. MonoHER did not reduce intracellular GSH levels. On the other hand, monoHER pretreatment significantly reduced doxorubicin-induced NF-κB activation.

Conclusion:

These results suggest that reduction of doxorubicin-induced NF-κB activation by monoHER, which sensitises cancer cells to apoptosis, is involved in the chemosensitising effect of monoHER in human liposarcoma cells.     

Id-1 regulates Bcl-2 and Bax expression through p53 and NF-κB in MCF-7 breast cancer cells

Although increasing evidence supports the protective role of inhibitor of differentiation and DNA binding-1 (Id-1) against anticancer drug-induced apoptosis, the underlying molecular mechanisms seem to vary depending on the tumor system. Here, we examined the direct role of Id-1 in MCF-7 breast cancer cells by ectopically overexpressing Id-1 under serum-free condition, where the endogenous Id-1 expression was suppressed. Id-1 expression resulted in increased number of viable cells, reduced Bax expression, enhanced Bcl-2 expression, but no change in Bcl-xL expression. The expression of nuclear factor-κB (NF-κB) was augmented, while those of p53 and IκB were reduced. Such changes in p53 and NF-κB pathways were also functional, as assessed by real-time polymerase chain reactions and reporter assays of their known downstream targets, p21 and Il-6, as well as Bax and Bcl-2 genes. Finally, Id-1 played a protective role against taxol-induced apoptosis in breast cancer cells as assessed by MTT assay and apoptotic cell count upon taxol treatment (0–200 nM). Reduced Bax expression and enhanced Bcl-2 expression by Id-1 were also noted in the presence of taxol. Taken together, we present a molecular mechanism where Id-1 regulates p53 and NF-κB pathways, which in turn regulates Bax and Bcl-2 genes, thus providing a survival advantage under exogenous stress such as serum-free or taxol treatment in MCF-7 breast cancer cells. In this regard, inactivation of Id-1 may provide a potential therapeutic strategy leading to inhibition of breast cancer progression and anti-cancer drug resistance. Hwan Kim and Heekyoung Chung equally contributed to this work.     

Defective NF-κB signaling in metastatic head and neck cancer cells leads to enhanced apoptosis by double-stranded RNA

Ligands to several Toll-like receptors (TLR), which mediate innate immune responses and chronic inflammation have been used as adjuvants to immunotherapy to enhance their antitumor activity. In particular, double-stranded RNAs that are cognate ligands of TLR3 have been used to trigger proapoptotic activity in cancer cells. However, a mechanistic understanding of TLR3-mediated apoptosis and its potential involvement in controlling tumor metastasis has been lacking. In this study, we used paired cell lines and fresh tumor specimens, derived from autologous primary and metastatic head and neck squamous cell carcinoma, to investigate the role of TLR3 signaling in metastatic progression. Compared with primary tumor cells, metastatic tumor cells were highly sensitive to TLR3-mediated apoptosis after double-stranded RNA treatment. Enhanced apoptosis in metastatic cells was dependent on double-stranded RNA and TLR3 and also the TLR3 effector signaling protein TRIF. Downstream responses requiring NF-κB were critical for apoptosis in metastatic cells, the defects in which could be resuscitated by alternative pathways of NF-κB activation. By elucidating how TLR3 ligands trigger apoptosis in metastatic cells, our findings suggest insights into how to improve their clinical use.     

α-TEA induces apoptosis of human breast cancer cells via activation of TRAIL/DR5 death receptor pathway

Vitamin E derivative RRR‐α‐tocopherol ether‐linked acetic acid analog (α‐TEA) induces apoptosis in MCF‐7 and HCC‐1954 human breast cancer cells in a dose‐ and time‐dependent manner. α‐TEA induces increased levels of tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) and death receptor‐5 (DR5) and decreased levels of antiapoptotic factor, cellular FLICE‐like inhibitory protein (c‐FLIP L). DR5/TRAIL induced apoptosis involves downregulation of c‐FLIP (L), caspase‐8 activation, activated proapoptotic mediators tBid and Bax, mitochondrial permeability transition, and activation of caspase‐9. siRNA knockdown of either DR5 or TRAIL blocks the ability of α‐TEA to enhance DR5 protein levels, downregulate c‐FLIP(L) protein levels and induce apoptosis. Combination of α‐TEA + TRAIL acts cooperatively to induce apoptosis, and increase DR5 and decrease c‐FLIP (L) protein levels. siRNA knockdown of c‐FLIP produces a low level of spontaneous apoptosis and enhances α‐TEA‐ and TRAIL‐induced apoptosis. Taken together, these studies show that α‐TEA induces TRAIL/DR5 mitochondria‐dependent apoptosis in human breast cancer cells, and that TRAIL/DR5‐dependent increases in DR5 and decreases in c‐FLIP expression are triggered by TRAIL or α‐TEA treatments. © 2010 Wiley‐Liss, Inc.     

CD24 enhances DNA damage-induced apoptosis by modulating NF-κB signaling in CD44-expressing breast cancer cells

Cluster of differentiation 24 (CD24) is a small glycosylphosphatidylinositol-linked cell surface molecule that is expressed in a variety of human carcinomas, including breast cancer. To determine the role of CD24 in breast cancer cells, we expressed CD24 in CD24-negative/low and cluster of differentiation 44 (CD44)-positive MDA-MB-231 metastatic breast cancer cells. Forced expression of CD24 resulted in a decrease in c-Raf/mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK)/mitogen-activated protein kinase signaling and reduced cell proliferation. Apoptosis induced by DNA damage was greatly enhanced in MDA-MB-231 CD24 cells as compared with MDA-MB-231 vec cells. CD24 expression efficiently attenuated DNA damage-induced nuclear factor-kappaB (NF-κB) signaling in MDA-MB-231 cells. However, in CD24-positive and CD44-negative/low MCF-7 cells, knockdown of CD24 did not significantly affect DNA damage-induced apoptosis nor NF-κB signaling. Silencing of CD24 in CD24/CD44-double-positive MDA-MB-468 cells partially rescued DNA damage-induced apoptosis. Transient transfection studies with 293T cells also revealed that CD24 attenuated cell viability and NF-κB signaling only when CD44 was cotransfected. These data indicate that CD24 expression potentiated DNA-induced apoptosis by suppressing antiapoptotic NF-κB signaling in CD44-expressing cells.     

Tim-3 promotes cell aggressiveness and paclitaxel resistance through NF-κB/STAT3 signalling pathway in breast cancer cells

Objective: Although T-cell immunoglobulin and mucin-domain containing molecule-3(Tim-3) has been recognized as a promising target for cancer immunotherapy, its exact role in breast cancer has not been fully elucidated.Methods: Tim-3 gene expression in breast cancer and its prognostic significance were analyzed. Associated mechanisms were then explored in vitro by establishing Tim-3-overexpressing breast cancer cells.Results: In a pooled analysis of The Cancer Genome Atlas(TCGA) database, Tim-3 g...     

Interferon-α sensitizes human gastric cancer cells to TRAIL-induced apoptosis via activation of the c-CBL-dependent MAPK/ERK pathway

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family that induces apoptosis in cancer cells. However, gastric cancer cells are insensitive to TRAIL. In the present study, we show that pretreatment with IFN-α enhanced TRAIL-induced apoptosis of gastric cancer MGC803 cells. IFN-α up-regulated death receptor 5 (DR5) expression and down-regulated survivin expression. Furthermore, extracellular-regulated protein kinase (ERK1/2) activation was induced by IFN-α, and a combination of IFN-α and TRAIL led to further activation of ERK1/2. Inhibition of the MAPK/ERK signaling pathway partially reversed apoptosis, as well as the expression patterns of DR5 and survivin. Moreover, the expression of the c-casitas B-lineage lymphoma (c-Cbl) family was down-regulated by IFN-α. Transfection of c-Cbl suppressed IFN-α-induced ERK activation. These results indicate that IFN-α enhances TRAIL-induced apoptosis in gastric cancer cells at least partially via downregulation of c-Cbl, and subsequent up-regulation of the MAPK/ERK pathway.