Pathway In MCF-7 Research Articles

Silibinin-induced mitochondria fission leads to mitophagy, which attenuates silibinin-induced apoptosis in MCF-7 and MDA-MB-231 cells

We reported previously that higher doses (150–250 μM) of silibinin enhanced fission and inhibited fusion of mitochondria, accompanying apoptosis of double-positive breast cancer cell line MCF-7 cells and triple-negative breast cancer cell line MDA-MB-231 cells. We report here three important questions yet unclarified in the previous study; 1) Whether enhanced fission of mitochondria by the treatment of silibinin leads to mitophagy, 2) Whether mitophagy positively contributes to apoptosis and 3) Whether estrogen receptor-positive (ER+) MCF-7 cells and estrogen receptor-negative (ER−) MDA-MB-231 cells are affected in a different way by silibinin treatment, since silibinin often works through ERs signaling pathway. Mitophagy driven by Pink1/Parkin signaling, plays an important role in eliminating damaged mitochondria. Indeed, increased expression of Pink1 and the recruitment of Parkin and LC3-II to mitochondria by the treatment with silibinin account for silibinin induction of mitophagy. In this study, the effects of mitochondrial division inhibitor 1 (mdivi-1) and small interfering RNA targeting dynamin-related protein 1 (DRP1) were examined to reveal the effect of mitochondrial fission on mitophagy. As expected, mdivi-1 or siRNA targeting DRP1 reversed silibinin-induced mitochondrial fission due to down-regulation in the expression of DRP1. Inhibition of mitochondrial fission by mdivi-1 prevented induction of mitophagy as well as autophagy in both MCF-7 and MDA-MB-231 cells, indicating that silibinin-induced mitochondrial fission leads to mitophagy. Inhibition of mitochondrial fission efficiently prevented silibinin-induced apoptosis in MCF-7 and MDA-MB-231 cells in our previous work, and the second point of the present study, inhibition of mitophagy by Pink1 or Parkin knockdown increased silibinin-induced apoptosis of these cells, respectively, suggesting that the mitophagy induced by silibinin treatment serves as a cytoprotective effect, resulting in reduction of apoptosis of cancer cells in both cells. In the third point, we studied whether estrogen receptors (ERs) played a role in silibinin-induced mitophagy and apoptosis in MCF-7 and MDA-MB-231 cells. ERα and ERβ are not involved in silibinin-induced mitophagic process in MCF-7 and MDA-MB-231 cells. These findings demonstrated that silibinin induced mitochondria fission leads to mitophagy, which attenuates silibinin-induced apoptosis not through ERs-Pink1 or -Parkin pathway in MCF-7 and MDA-MB-231.

BMX activates Wnt/β-catenin signaling pathway to promote cell proliferation and migration in breast cancer.

Breast cancer has become a dangerous killer for the female, which seriously threatened women's life, leading to huge pressures to society. The present study assessed the mechanism underlying the involvement of bone marrow tyrosine kinase on chromosome X (BMX) in breast cancer development. The expression of BMX was examined by qPCR and immunohistochemistry. The effect of BMX on cell proliferation and migration was detected by Clone formation assay and Transwell assay. In vitro study, the correlation of BMX with Wnt/β-catenin pathway was explored by western blot and TOP/FOP flash assay. In the present study, we found that BMX was up-regulated in breast cancer, which was associated with the tumor differentiation and TNM stage. Oncogenic BMX enhanced the ability of breast cancer cell proliferation and migration. Furthermore, BMX could up-regulate the protein expression levels of p-β-catenin (Y142), p-β-catenin(Y654) and inhibit the expression level of p-β-catenin (S33/37), thus activating Wnt/β-catenin pathway in MCF-7 and MDA-MB-231 cells. In addition, we revealed that BMX promoted GSK3β phosphorylation, which suppressed the degradation of β-catenin. In this study, we identified that BMX-activated Wnt/β-catenin signaling pathway, playing an oncogenic role in breast cancer, suggesting that BMX could become a potential treatment target of breast cancer.

Comparison of transcriptome expression alterations by chronic exposure to low-dose bisphenol A in different subtypes of breast cancer cells

The impacts of chronic bisphenol A (BPA) exposure suspected to be a potential risk factor for breast cancer progression are not thoroughly understood in different subtypes of breast cancer cells (BCCs). This study aimed to compare the differentially expressed genes (DEGs) and biological functions in MCF-7 (luminal A), SK-BR3 (HER2–enriched) and MDA-MB-231 (triple–negative) cells exposed to BPA at an environmentally human-relevant low dose (10−8 M) for 30 days, by using the approach of RNA sequencing and online informatics tools. BPA-exposure resulted in 172, 137, and 139 DEGs in MCF-7/BPA, SK-BR3/BPA, and MDA-MB-231/BPA, respectively. The significantly enriched gene ontology terms of DEGs in each cell were different: cellular response to gonadotropin-releasing hormone, negative regulation of fibrinolysis, choline metabolism, glutamate signaling pathways and coagulation pathway in MCF-7/BPA; positive regulation of inflammatory response and VEGF/VEGFR signaling pathways in SK-BR3/BPA; negative regulation of keratinocyte proliferation and HIF signaling pathways in MDA-MB-231/BPA cells. The immune network analysis of DEGs across the breast cancer cells indicated NKT, NK and T cell activation and dendritic cell migration by regulating the expression of immunomodulatory genes. High expression of IL19, CA9 and SPARC identified in MCF-7/BPA, SK-BR3/BPA, and MDA-MB-231/BPA are detrimental gene signatures to predict poor overall survival in luminal A, HER2-enriched and triple–negative breast cancer patients, respectively. These findings indicate chronic BPA exposure has dissimilar impacts on the regulation of gene expression and diverse biological functions, including immune modulation, in different subtypes of BCCs.

The unfolded protein response controls endoplasmic reticulum stress-induced apoptosis of MCF-7 cells via a high dose of vitamin C treatment.

Recent in vitro studies have shown that vitamin C (Vit C) with pro-oxidative properties causes cytotoxicity of breast cancer cells by selective oxidative stress. However, the effect of Vit C in itself at different concentration levels on MCF-7 breast cancer cell line after 24h, has not yet been described. We aimed to examine the effect of Vit C on the viability and signalling response of MCF-7/WT (MCF-7 wild-type) cells that were exposed to various concentrations (0.125-4mM) of Vit C during 24h. The cytotoxic effect of Vit C on MCF-7/VitC (MCF-7/WT after added 2mM Vit C) was observed, resulting in a decrease of cell index after 12h. Also, the cytotoxicity of Vit C (2mM) after 24h was confirmed by flow cytometry, i.e., increase of dead, late apoptotic, and depolarized dead MCF-7/VitC cells compared to MCF-7/WT cells. Moreover, changes in proteomic profile of MCF-7/VitC cells compared to the control group were investigated via label-free quantitative mass spectrometry and post-translational modification. Using bioinformatics assessment (i.e., iPathwayGuide and SPIA R packages), a significantly impacted pathway in MCF-7/VitC was identified, namely the protein processing in endoplasmic reticulum. The semi-quantitative change (log2fold change = 4.5) and autophosphorylation at Thr-446 of protein kinase (PKR) (involved in this pathway) indicates that PKR protein could be responsible for the unfolded protein response and inhibition of the cell translation during endoplasmic reticulum stress, and eventually, for cell apoptosis. These results suggest that increased activity of PKR (Thr-446 autophosphorylation) related to cytotoxic effect of Vit C (2mM) may cause the MCF-7 cells death.

Effects of different glucose concentrations on the leptin signaling pathway in MCF-7 and T47D breast cancer cells.

Leptin activates multiple intracellular signaling pathways, including JAK/STAT, by binding to its receptor. Leptin is also an important regulator of glucose homeostasis. Although both glucose and leptin increase breast cancer cell proliferation in vitro, whether the enhancing effect of glucose on the proliferation of breast cancer cells is mediated by the leptin signaling pathway is not known. The aim of this study was to investigate the effect of different glucose concentrations on the leptin signaling pathway in MCF-7 and T47D breast cancer cells. MCF-7 and T47D cell proliferation in different glucose concentrations (2.5 mM, 5 mM, 25 mM, or 50 mM) were assayed using CCK-8 assay. Leptin, leptin receptors (ObR, ObRb) as well as STAT3 mRNA and protein levels in both cell lines in different glucose concentrations were examined by RT-PCR and western blot, respectively. Incubation in 2.5 mM, 5 mM, 25 mM, or 50 mM glucose for 72h significantly increased the proliferation of both MCF-7 and T47D cells compared to 0 mM glucose incubated cells (P<0.001). mRNA levels of leptin, ObR, ObRb or STAT3 in 2.5 mM, 5 mM, 25 mM, or 50 mM glucose incubated cells were not significantly different in both cell lines compared to 0 mM (p>0.05). However, ObR protein levels in MCF-7 cells incubated in 25 mM glucose was significantly lower compared to 0 mM glucose by western blot (p<0.05). Our data suggest that the enhancing effect of glucose on breast cancer cell proliferation is not mediated by the JAK/STAT pathway.

Mechanisms of Matrix-Induced Chemoresistance of Breast Cancer Cells—Deciphering Novel Potential Targets for a Cell Sensitization

Tumor cell binding to microenvironment components such as collagen type 1 (COL1) attenuates the sensitivity to cytotoxic drugs like cisplatin (CDDP) or mitoxantrone (MX), referred to as cell adhesion mediated drug resistance (CAM-DR). CAM-DR is considered as the onset for resistance mutations, but underlying mechanisms remain elusive. To evaluate CAM-DR as target for sensitization strategies, we analyzed signaling pathways in human estrogen-positive MCF-7 and triple-negative MDA-MB-231 breast cancer cells by western blot, proteome profiler array and TOP-flash assay in presence of COL1. β1-Integrins, known to bind COL1, appear as key for mediating COL1-related resistance in both cell lines that primarily follows FAK/PI3K/AKT pathway in MCF-7, and MAPK pathway in MDA-MB-231 cells. Notably, pCREB is highly elevated in both cell lines. Consequently, blocking these pathways sensitizes the cells evidently to CDDP and MX treatment. Wnt signaling is not relevant in this context. A β1-integrin knockdown of MCF-7 cells (MCF-7-β1-kd) reveals a signaling shift from FAK/PI3K/AKT to MAPK pathway, thus CREB emerges as a promising primary target for sensitization in MDA-MB-231, and secondary target in MCF-7 cells. Concluding, we provide evidence for importance of CAM-DR in breast cancer cells and identify intracellular signaling pathways as targets to sensitize cells for cytotoxicity treatment regimes.

Apoptosis induction in human breast cancer cell lines by synergic effect of raloxifene and resveratrol through increasing proapoptotic genes

AimsBreast cancer is the most common cancer of women. The aim of this study was to investigate the synergic effect of raloxifene (Ral) and resveratrol (Res) on apoptosis of breast cancer cell lines (MCF7 and MDA-MB-231). Main methodsCells were treated with Ral and Res alone and in combination. Cell viability (MTT assay), apoptosis (TUNEL assay) and nitric oxide (NO) production (Griess method) were investigated. Expression of proapoptotic gene (Bax and p53), anti-apoptotic gene (Bcl2) and caspases-3, caspase -8 were evaluated. One-way ANOVA test was used for data analysis. Key findingsThe viabilities of MCF7 and MDA-MB-231 cells treated by Ral (1 μM) and Res (20 μM) decreased significantly (p = 0.000) and their synergic use showed more reduction. Nitric oxide production by MCF7 and MDA-MB-231 cells exposed upon each drug alone and in combination showing a significant reduction (p = 0.000). There was also an increase in apoptosis in the cells treated with combination use of Ral and Res in both cell lines. Moreover, reduced expression of Bcl2 and increased expression of Bax and p53 genes were observed. SignificanceThe synergic effects of Ral and Res through increased ratio of Bcl2/Bax and expressions of p53, caspase-3 and caspase-8 genes indicating a better therapeutic effect on breast cancer cells relative to each drug alone. Combination of Res and Ral via increased expression of apoptotic genes including Bax, p53 and caspase-3 and caspase-8 is able to promote apoptosis as a mitochondrial dependent pathway in MCF7 and MDA-MB-231. The synergic effect was more potent in MCF7 estrogen receptor positive cell line.

2'-Hydroxyflavanone effectively targets RLIP76-mediated drug transport and regulates critical signaling networks in breast cancer.

Breast cancer (BC) is the most common cancer in women. Estrogen, epidermal growth factor receptor 2 (ERBB2, HER2), and oxidative stress represent critical mechanistic nodes associated with BC. RLIP76 is a major mercapturic acid pathway transporter whose expression is increased in BC. In the quest of a novel molecule with chemopreventive and chemotherapeutic potential, we evaluated the effects of 2'-Hydroxyflavanone (2HF) in BC. 2HF enhanced the inhibitory effects of RLIP76 depletion and also inhibited RLIP76-mediated doxorubicin transport in BC cells. RNA-sequencing revealed that 2HF induces strong reversal of the gene expression pattern in ER+MCF7, HER2+ SKBR3 and triple-negative MDA-MB-231 BC cells with minimal effects on MCF10A normal breast epithelial cells. 2HF down regulated ERα and enhanced inhibitory effects of imatinib mesylate/Gleevec in MCF7 cells. 2HF also down regulated ERα and HER2 gene networks in MCF7 and SKBR3 cells, respectively. 2HF activated TP53 and inhibited TGFβ1 canonical pathway in MCF7 and MDA-MB-231 BC cells. 2HF also regulated the expression of a number of critical prognostic genes of MammaPrint panel and their upstream targets including TP53, CDKN2A and MYC. The collective findings from this study provide a comprehensive, direct and integrated evidence for the benefits of 2HF in targeting major and clinically relevant mechanistic regulators of BC.

Dietary isoflavone daidzein synergizes centchroman action via induction of apoptosis and inhibition of PI3K/Akt pathway in MCF-7/MDA MB-231 human breast cancer cells

BackgroundDespite advancements in the prognosis and management of breast cancer, it remains a major cause of mortality in women worldwide. Centchroman (CC), an oral contraceptive has been found to exhibit anti-cancer potential against a wide range of cancer including breast cancer. PurposeThe present study is intended to evaluate the ability of soy isoflavone Daidzein (DZ) in enhancing the efficacy of CC in Human Breast Cancer Cells (HBCCs). Methods/Study designSulforhodamine B assay was employed to determine the cytotoxicity induced by 10 µM CC & 50 µM DZ separately and together in MCF-7/MDA MB-231 HBCCs and non-tumorigenic Human Mammary Epithelial Cells (HMECs) MCF-10A as a control. Combination Index (CI) analysis was executed using CompuSyn software. Further, apoptosis was assessed using Annexin V/PI, AO/PI staining and tunel assay. Cell cycle, reactive oxygen species generation and mitochondrial membrane potential alteration was determined using flow cytometry. Western blot analysis was performed to check the expression of respective proteins. ResultsThe results suggest that the combination exerts elevated toxicity as compared to control and each drug per se without affecting HMECs MCF-10A. This therefore implies cancer cell specific action of CC plus DZ administered together. Additionally, combination index analysis suggests synergistic action of CC and DZ combination in HBCCs. Cell cycle analysis, Annexin V/PI staining, tunel assay and western blot analysis confirms the induction of apoptosis by combination in HBCCs. Interestingly, western blot analysis also revealed that the combination down-regulated the expression of proteins involved in cell survival i.e. PI3K, Akt and mTOR, suggesting inhibition of cell survival pathway. ConclusionThe results overall demonstrate that CC plus DZ has higher anticancer efficacy as compared to either drug alone. Hence, the combination of CC plus DZ may offer a novel strategy for the management of breast cancer.

Calycosin inhibits the in vitro and in vivo growth of breast cancer cells through WDR7-7-GPR30 Signaling

BackgroundClinically, breast cancer is generally classified into estrogen receptor-positive (ER+) or estrogen receptor-negative (ER−) subtypes. The phytoestrogen calycosin has been shown to inhibit the proliferation of ER+ cells, which may be mediated by a feedback loop that involves miR-375, RAS dexamethasone-induced 1 (RASD1), and ERα. However, how calycosin acts on ER− breast cancer cells remains unclear.ResultsHere, we show that calycosin inhibited the proliferation of both ER− (MDA-MB-468 and SKBR3) and ER+ breast cancer cells (MCF-7 and T47D) and that these inhibitory effects were associated with the up-regulation of the long non-coding RNA (lncRNA) WDR7-7. For the first time, we demonstrate that the expression of WDR7-7 is reduced in breast cancer cell lines and that the overexpression of WDR7-7 inhibits growth through a mechanism that involves G-protein coupled estrogen receptor 30 (GPR30). Meanwhile, we show that calycosin stimulated the WDR7-7-GPR30 signaling pathway in MCF-7, T47D, MDA-MB-468, and SKBR3 breast cancer cells. In contrast, in MCF10A and GPR30-deficient MDA-MB-231 cells, due to a lack of WDR7-7-GPR30 for activation, calycosin failed to inhibit cell growth. Additionally, in all four GPR30-positive breast cancer lines, calycosin decreased the phosphorylation levels of SRC, EGFR, ERK1/2 and Akt, but the inhibition of WDR7-7 blocked these changes and increased proliferation. In mice bearing MCF-7 or SKBR3 xenografts, tumor growth was inhibited by calycosin, and changes in expression the levels of WDR7-7 and GPR30 in tumor tissues were similar to those in cultured MCF-7 and SKBR3 cells.ConclusionsThese results suggest the possibility that calycosin inhibited the proliferation of breast cancer cells, at least partially, through WDR7-7-GPR30 signaling, which may explain why calycosin can exert inhibitory effects on ER− breast cancer.

Multifunctional Nanoparticles Loading with Docetaxel and GDC0941 for Reversing Multidrug Resistance Mediated by PI3K/Akt Signal Pathway.

The polylactic-co-glycolic acid polyethylene glycol conjugated with cell penetrating peptide R7 (PLGA-PEG-R7)/polysulfadimethoxine-folate nanoparticles loaded with docetaxel (DTX) and GDC0941 (R7/PSD-Fol NPs) were prepared to overcome multidrug resistance (MDR) and enhance the antitumor activity. First, polysulfadimethoxine-folate was synthesized to construct the R7/PSD-Fol NPs. The R7/PSD-Fol NPs were prepared with the abilities of effective entrapment and drug loading. Due to the pH-sensitive effect of PSD-folate, the releasing of DTX and GDC0941 from the R7/PSD-Fol NPs was lower in pH 7.4 buffer solution than that in pH 5.0 buffer solution. The half maximal inhibitory concentration (IC50) of MCF-7 and resistant to doxorubicin (MCF-7/Adr) cells illustrated the cytotoxicity of R7/PSD-Fol nanoparticles by using the MTT method. The uptake of R7/PSD-Fol NPs was visualized by using the fluorescence of Rh-123 to detect the targeting effect of folate on the surface of R7/PSD-Fol NPs. The results of the cell apoptosis and the depolarization of mitochondrial membrane potential (MMP) were adopted to show the cytotoxicity of the R7/PSD-Fol NPs on MCF-7/Adr cells. The Western blot revealed the inhibition of PI3K/Akt pathway in MCF-7/Adr cells induced by R7/PSD-Fol NPs. Finally, both in vivo distribution and in vivo antitumor showed the R7/PSD-Fol NPs displayed the better distribution at tumor site and the stronger suppression of tumor growth in the tumor bearing nude mice compared with control group. It was concluded that R7/PSD-Fol NPs loaded with DTX and GDC0941 could overcome MDR and enhance the antitumor effect further.

The role of epithelial cell adhesion molecule N-glycosylation on apoptosis in breast cancer cells.

Glycosylation of cell surface proteins plays an important role in the regulation of apoptosis. It has been demonstrated that knockdown of epithelial cell adhesion molecule promoted apoptosis, inhibited cell proliferation, and caused cell-cycle arrest. In this study, we investigated whether and how N-glycosylation of epithelial cell adhesion molecule influenced the apoptosis in breast cancer cells. We applied the N-glycosylation mutation epithelial cell adhesion molecule plasmid to express deglycosylation of epithelial cell adhesion molecule and then to study its function. Our results showed that deglycosylation of epithelial cell adhesion molecule promoted apoptosis and inhibited cell proliferation. Deglycosylation of epithelial cell adhesion molecule enhanced the cytotoxic effect of 5-fluorouracil, promoting apoptosis by downregulating the expression of the anti-apoptotic protein Bcl-2 and upregulating the expression of the pro-apoptotic proteins Bax and Caspase 3 via the extracellular-signal-regulated kinase 1/2 and c-Jun N-terminal kinase mitogen-activated protein kinase signaling pathways in MCF-7 and MDA-MB-231 cells. These findings are important for a better understanding of epithelial cell adhesion molecule apoptosis regulation and suggest epithelial cell adhesion molecule as a potential target for the treatment of breast cancer.

In vitro Antiproliferative and Apoptosis Inducing Effect of Allium atroviolaceum Bulb Extract on Breast, Cervical, and Liver Cancer Cells.

Natural products are considered potent sources for novel drug discovery and development. The multiple therapeutic effects of natural compounds in traditional medicine motivate us to evaluate the cytotoxic activity of bulb of Allium atroviolaceum in MCF7 and MDA-MB-231, HeLa and HepG2 cell lines. The bulb methanol extract of A. atroviolaceum was found to be an active cell proliferation inhibitor at the time and dose dependent manner. Determination of DNA content by flow cytometry demonstrated S and G2/M phase arrest of MCF-7 cell, correlated to Cdk1 downregulation, S phase arrest in MDA-MB-231 which is p53 and Cdk1-dependent, sub-G0 cell cycle arrest in HeLa aligned with Cdk1 downregulation, G0/G1, S, G2/M phase arrest in HepG2 which is p53-dependent. Apoptosis as the mechanism of cell death was confirmed by morphology study, caspases activity assay, as well as apoptosis related gene expression, Bcl-2. Caspase-8, -9, and -3 activity with downregulation of Bcl-2 illustrated occurrence of both intrinsic and extrinsic pathways in MCF7, while caspase-3 and -8 activity revealed extrinsic pathway of apoptosis, although Bcl-2 downregulated. In HeLa cells, the activity of caspase-9 and -3 and downregulation of Bcl-2 shows intrinsic pathway or mitochondrial pathway, whereas HepG2 shows caspase independent apoptosis. Further, the combination of the extract with tamoxifen against MCF7 and MDA-MB-231 and combination with doxorubicin against HeLa and HeG2 demonstrated synergistic effect in most concentrations, suggests that the bulb of A. atroviolaceum may be useful for the treatment of cancer lonely or in combination with other drugs.

A novel β-diiminato manganeseIII complex as the promising anticancer agent induces G0/G1 cell cycle arrest and triggers apoptosis via mitochondrial-dependent pathways in MCF-7 and MDA-MB-231 human breast cancer cells

Novel β-diiminato manganeseIII complex has shown promising anti-breast cancer activity.

SET protein overexpression contributes to paclitaxel resistance in MCF-7/S cells through PI3K/Akt pathway

Patient SE translation (SET) is a carcinogen in facilitating cellular growth and proliferation, and promoting tumorigenesis and metastasis. The present study was to investigate the resistance mechanisms associated with SET in paclitaxel-induced human breast cancer cells. The different expressions of SET, ATP-binding cassette (ABC) transporters and PI3K/Akt pathway between paclitaxel sensitive MCF-7/S and paclitaxel resistant MCF-7/PTX cells were identified using western blotting. We adopted plasmid transfection to upregulate SET in MCF-7/S cells and a novel SET antagonist COG112 to decrease SET in MCF-7/PTX cells. Subsequently, cell viability to paclitaxel was assessed by MTT assay and cell apoptosis was analyzed by flow cytometry. We found that levels of SET, ABC transporters and PI3K/Akt pathway were elevated in MCF-7/PTX. Upregulation of SET in MCF-7/S cells expressed resistant to paclitaxel and decreased cell apoptosis. Moreover, overexpression of SET promoted the mRNA and protein level of ABC transporters and PI3K/Akt signal pathway in MCF-7/S cells. Conversely, decreased level of SET by COG112 not only significantly sensitized MCF-7/PTX cells to paclitaxel, but also enhanced paclitaxel-induced cell apoptosis. Additionally, the levels of the ABC transporters and PI3K/Akt signal pathway were also reduced in the COG112-treated MCF-7/PTX cells. The above results demonstrated that SET was associated with paclitaxel resistance in MCF-7/PTX cells.

2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol inhibits MDM2 and induces apoptosis in breast cancer cells through a p53-independent pathway

2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ) is a novel synthesized combretastatin A-4 (CA-4) analog that can be classified as a microtubule inhibitor. Our previous study demonstrated that SQ induced G2/M phase arrest and promoted apoptosis progression in breast cancer cells. In the present study, we found that SQ dissociated the MDM2-p53 complex and directly induced MDM2 degradation through the ubiquitin-dependent proteasome pathway in MCF-7 and MDA-MB-231 cells. Further, p53 was activated by SQ through regulation of its transcription, translation, and post-translation modification. More specifically, we demonstrated that SQ induced caspase-dependent but p53-independent apoptosis, and this apoptosis is associated with the inhibition of MDM2. We also showed that SQ exhibited superior in vivo efficacy and low toxicity than CA-4. The immunofluorescence histochemistry study indicated that SQ also inhibited MDM2 expression in vivo. In summary, we report for the first time that SQ shows excellent anti-breast cancer activity in vivo and in vitro and induces p53-independent apoptosis, which is associated with MDM2 inhibition. Therefore, the novel compound SQ has potential for therapeutic treatment of both wild-type and mutant p53 breast cancer.

Silver nanoparticles induce irremediable endoplasmic reticulum stress leading to unfolded protein response dependent apoptosis in breast cancer cells.

Nowadays, silver nanoparticles (AgNP) are widely used in the medical field mainly for their antibacterial properties. Although some studies report a cytotoxic activity of the particles, the mechanisms involved in AgNP-induced cell death remain to be determined. Herein, we report that AgNP of 2 (AgNP2) and 15nm (AgNP15) induce apoptosis in human MCF-7 and T-47D breast cancer cells. Treatment with AgNP2 and AgNP15 led to accumulation and aggregation of misfolded proteins causing an endoplasmic reticulum (ER) stress and activating the unfolded protein response (UPR). The three main ER sensors, PERK, IRE-1α and ATF-6, were rapidly activated in response to AgNP2 and AgNP15. Although Grp78 levels remained unchanged, AgNP2 and AgNP15 induced upregulation of the transcription factors ATF-4 and GADD153/CHOP. Moreover, the initiating caspase-9 and the effector caspase-7 were activated in response to these NPs. The expression levels of the pro-apoptotic BIM and BAD proteins remained unchanged. In contrast, a downregulation of Mcl-1 and xIAP protein expression as well as a processing of PARP were observed. Pharmacological inhibition of PERK kinase and IRE-1 endonuclease activities, as well as inhibition of ER-stress, partially protected cells from AgNP2- and AgNP15-induced apoptosis. Of note, the non-cancerous MCF-10A cells were more resistant to both AgNP2 and AgNP15 when compared to MCF-7 and T-47D cell lines. Taken together, our results demonstrate that AgNP induce ER stress and can target the UPR-dependent apoptotic pathway in MCF-7 and T-47D, which highlights new potential strategies for the treatment of breast cancers.

Dioscin strengthens the efficiency of adriamycin in MCF-7 and MCF-7/ADR cells through autophagy induction: More than just down-regulation of MDR1.

The purpose of present study was to investigate the effect of dioscin on activity of adriamycin (ADR) in ADR-sensitive (MCF-7) and ADR-resistant (MCF-7/ADR) human breast cancer cells and to clarify the molecular mechanisms involved. Antiproliferation effect of ADR was enhanced by dioscin in MCF-7 and MCF-7/ADR cells. Dioscin significantly inhibited MDR1 mRNA and protein expression and MDR1 promoter and nuclear factor κ-B (NF-κB) activity in MCF-7/ADR cells. Additionally, inhibitor κB-α (IκB-α) degradation was inhibited by dioscin. Moreover, dioscin induced the formation of vacuoles in the cytoplasm and protein level of LC3-II in MCF-7 and MCF-7/ADR cells. Autophagy inhibitor 3-MA abolished the effect of dioscin on ADR cytotoxicity. Dioscin inhibited phosphorylation of PI3K and Akt, resulting in upregulation of LC3-II expression. In conclusion, dioscin increased ADR chemosensitivity by down-regulating MDR1 expression through NF-κB signaling inhibition in MCF-7/ADR cells. Autophagy was induced by dioscin to ameliorate the cytotoxicity of ADR via inhibition of the PI3K/AKT pathways in MCF-7 and MCF-7/ADR cells. These findings provide evidence in support of further investigation into the clinical application of dioscin as a chemotherapy adjuvant.

Histone deacetylase inhibitor reverses multidrug resistance by attenuating the nucleophosmin level through PI3K/Akt pathway in breast cancer.

The development of multidrug resistance (MDR) is the major obstacle in the chemotherapy of breast cancer, and it restricts the application of antitumor drugs in the clinic. Therefore it is urgent to search for ways to reverse MDR and restore sensitivity to chemotherapeutics in breast carcinoma. Currently, histone deacetylase inhibitors (HDACIs) offer a promising strategy for tumor therapy as the effective anticancer drugs. Based on the potential resistant target of nucleophosmin (NPM), the purpose of this study was to explore the reversal effect of a new synthetic histone deacetylase inhibitor, FA17, on MDR in methotrexate-resistant breast cancer cells (MCF-7/MTX) and xenograft tumors. It was shown that the abnormal expression of NPM induced MDR and inhibited downstream mitochondrial apoptotic pathway by activating PI3K/Akt signaling pathway in MCF-7/MTX cells. The reversal effect and molecular mechanism of FA17 were investigated both in vitro and in vivo. We found that FA17 could significantly reverse resistance and sensitize MCF-7/MTX cells to methotrexate. FA17 obviously enhanced resistant cell apoptosis, inhibited expressions of NPM and efflux transporters. Additionally, FA17 could reverse MDR via inactivating PI3K/Akt pathway and accelerating mitochondrial apoptotic pathway both in MCF-7/MTX cells and in xenograft tumors. Taken together, the novel histone deacetylase inhibitor could effectively reverse drug resistance due to suppressing the activity of NPM and drug efflux pumps by PI3K/Akt and mitochondrial apoptotic pathway. The above not only indicated the potential applied value of FA17 in reversing MDR and enhancing the sensitivity of chemotherapy, but also confirmed the role of NPM in the development of MDR in breast cancer.

Flavone inhibits migration through DLC1/RhoA pathway by decreasing ROS generation in breast cancer cells

Tumor suppressor protein deleted in liver cancer 1 (DLC1) is a RhoGTPase-activating protein (RhoGAP) and inhibits cancer cell migration by inactivating downstream target protein RhoA. A few studies have reported the regulations of reactive oxygen species (ROS) on RhoGAP. In this study, we investigated flavone (the core structure of flavonoids)-induced regulation on ROS generation and DLC1/RhoA pathway in MCF-7 and MDA-MB-231 breast cancer cells and explored whether flavone-induced upregulation of DLC1 is mediated by ROS. Our results showed that flavone decreased ROS production and inhibited cell migration through DLC1/RhoA pathway. To further investigate the role of ROS in flavone-induced regulation on DLC1/RhoA pathway, hydrogen peroxide was added to restore the ROS levels. Flavone-induced upregulation of DLC1 expression, downregulation of RhoA activity, and inhibition of cell migration were all restrained by hydrogen peroxide. We also found that flavone increased DLC1 stability by inhibiting DLC1 protein degradation in breast cancer cells. In summary, our study demonstrated that flavone inhibited cell migration through DLC1/RhoA pathway by decreasing ROS generation and suppressed DLC1 degradation in MCF-7 and MDA-MB-231 breast cancer cells.