Reduced Breast Cancer Cell Research Articles

Sulfobetaine methacrylate-functionalized graphene oxide-IR780 nanohybrids aimed at improving breast cancer phototherapy.

The application of Graphene Oxide (GO) in cancer photothermal therapy is hindered by its lack of colloidal stability in biologically relevant media and modest Near Infrared (NIR) absorption. In this regard, the colloidal stability of GO has been improved by functionalizing its surface with poly(ethylene glycol) (PEG), which may not be optimal due to the recent reports on PEG immunogenicity. On the other hand, the chemical reduction of GO using hydrazine hydrate has been applied to enhance its photothermal capacity, despite decreasing its cytocompatibility. In this work GO was functionalized with an amphiphilic polymer containing [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) brushes and was loaded with IR780, for the first time, aiming to improve its colloidal stability and phototherapeutic capacity. The attained results revealed that the SBMA-functionalized GO displays a suitable size distribution, neutral surface charge and adequate cytocompatibility. Furthermore, the SBMA-functionalized GO exhibited an improved colloidal stability in biologically relevant media, while its non-SBMA functionalized equivalent promptly precipitated under the same conditions. By loading IR780 into the SBMA-functionalized GO, its NIR absorption increased by 2.7-fold, leading to a 1.2 times higher photothermal heating. In in vitro cell studies, the combination of SBMA-functionalized GO with NIR light only reduced breast cancer cells' viability to 73%. In stark contrast, by combining IR780 loaded SBMA-functionalized GO and NIR radiation, the cancer cells' viability decreased to 20%, hence confirming the potential of this nanomaterial for cancer photothermal therapy.

Downregulation of 15-hydroxyprostaglandin dehydrogenase during acquired tamoxifen resistance and association with poor prognosis in ERα-positive breast cancer.

Aim:Tamoxifen (TAM) resistance remains a clinical issue in breast cancer. The authors previously reported that 15-hydroxyprostaglandin dehydrogenase (HPGD) was significantly downregulated in tamoxifen-resistant (TAMr) breast cancer cell lines. Here, the authors investigated the relationship between HPGD expression, TAM resistance and prediction of outcome in breast cancer.Methods:HPGD overexpression and silencing studies were performed in isogenic TAMr and parental human breast cancer cell lines to establish the impact of HPGD expression on TAM resistance. HPGD expression and clinical outcome relationships were explored using immunohistochemistry and in silico analysis.Results:Restoration of HPGD expression and activity sensitised TAMr MCF-7 cells to TAM and 17β-oestradiol, whilst HPGD silencing in parental MCF-7 cells reduced TAM sensitivity. TAMr cells released more prostaglandin E2 (PGE2) than controls, which was reduced in TAMr cells stably transfected with HPGD. Exogenous PGE2 signalled through the EP4 receptor to reduce breast cancer cell sensitivity to TAM. Decreased HPGD expression was associated with decreased overall survival in ERα-positive breast cancer patients.Conclusions:HPGD downregulation in breast cancer is associated with reduced response to TAM therapy via PGE2-EP4 signalling and decreases patient survival. The data offer a potential target to develop combination therapies that may overcome acquired tamoxifen resistance.

Progesterone Receptor B signaling Reduces Breast Cancer Cell Aggressiveness: Role of Cyclin-D1/Cdk4 Mediating Paxillin Phosphorylation.

Progesterone-Receptor (PR) positivity is related with an enhanced response to breast cancer therapy, conversely cyclin D1 (CD1) is a retained marker of poor outcome. Herein, we demonstrate that hydroxyprogesterone (OHPg) through progesterone receptor B (PR-B) reduces breast cancer cell aggressiveness, by targeting the cytoplasmic CD1. Specifically, OHPg diminishes CD1 expression by a transcriptional regulation due to the recruitment of PR-B at a canonical half-PRE site of the CD1 promoter, together with HDAC1, determining a chromatin conformation less prone for gene transcription. CD1, together with its kinase partner Cdk4, regulates cell migration and metastasis, through the association with key components of focal adhesion, such as Paxillin (Pxn). Kaplan-Meier analysis shows that low Pxn expression was associated with increased distant metastasis-free survival in luminal A PR+ breast carcinomas. Interestingly, OHPg treatment reduced Pxn content in T47-D and MCF-7 cells; besides, the interaction between endogenous cytoplasmic CD1/Cdk4 with Pxn was reduced. This was consistent with the reduction of p-Ser83Pxn levels, crucially causing the delay in cell migration and a concomitant inhibition of Rac1 activity and p-PAK. Collectively, these findings support the role of PR-B in breast epithelial cell integrity and reinforce the importance in targeting PR-B as a potential strategy to restrict breast tumor cell invasion and metastasis.

Luteolin exhibits anti-breast cancer property through up-regulating miR-203

Luteolin is a representative of natural flavonoid that has anti-tumour properties. This study designed to check its impact on breast cancer and the underlying mechanisms. MDA-MB-453 and MCF-7 cells were administrated with luteolin and the following techniques were carried out: CCK-8 assay, FITC-PI double-staining and Western blot. qRT-PCR analysis was utilized to see the effects of luteolin on miR-203 expression. Besides, miR-203 expression was silenced by transfection with specific inhibitor. Luteolin remarkably declined MDA-MB-453 and MCF-7 cells viability and accelerated apoptosis which accompanied by Bax up-regulation, Bcl-2 down-regulation and Caspase-3 cleavage. Also, luteolin impeded TGFβ1-induced EMT, as evidenced by the decreased levels of Vimentin, Zeb1 and N-cadherin, as well as the increased level of E-cadherin. miR-203 was highly expressed in 22 pair of breast cancer tissues than the matched paracancerous tissues. Luteolin could elevate miR-203 level. Besides, luteolin’s anti-tumour effects were partially eliminated by miR-203 silence. Further, luteolin inhibited Ras/Raf/MEK/ERK signalling, while the inhibitory effects were flattened by miR-203 silence. Luteolin significantly reduced breast cancer cells growth and EMT. Luteolin exerted its anti-tumour effects possibly involved the elevated expression of miR-203 and the inhibited Ras/Raf/MEK/ERK signalling.

Inhibition of sirtuin 1 deacetylase by miR-211-5p provides a mechanism for the induction of cell death in breast cancer cells

Sirtuin 1 is one of the regulators of cell growth and survival and its inhibition is suggested as a suitable mechanism to overcome breast cancer development. In this study we explored the role of miR-211-5p in SIRT1/p53 pathway and its influence on breast cancer cell viability and apoptosis. Cells were transfected with miR-211-5p mimic and inhibitor to modulate cellular miR-211-5p levels in breast cancer cell lines, MDA-MB-231 and MCF-7. Gene expression of miR-211-5p and SIRT1 were measured with real-time PCR. SIRT1 protein level and the acetylation of p53 as well as SIRT1 activity were evaluated by Western blotting and fluorometry, respectively. In order to explore the direct attachment of miR-211-5p to the 3′-UTR of SIRT1 mRNA, luciferase reporter assay was applied. Cell viability in response to miR-211-5p was studied by MTT assay and apoptosis was assessed by annexin V labeling followed by flow cytometry. Results showed that SIRT1 gene and protein expression were inhibited by miR-211-5p and the 3′-UTR of SIRT1 was found to be directly targeted by miR-211-5p. Inhibition of SIRT1 expression resulted in its reduced activity. Up-regulation of miR-211-5p was also followed by a significant decline in the acetylation status of p53 which was associated with remarkable decreased cell viability and induction of apoptosis in breast cancer cells. Antisense oligonucleotide of miR-211-5p acted as its inhibitor and exerted opposite effects both on SIRT1 expression and cell apoptosis. In conclusion, inhibition of SIRT1 by miR-211-5p could effectively reduce breast cancer cell survival and cause cell death and therefore might be considered a seemly mechanism for designing anticancer therapies.

Traumatic acid toxicity mechanisms in human breast cancer MCF-7 cells

Traumatic acid (TA) – an oxidative derivative of unsaturated fatty acids, belongs to the cytokinins category – a group of plant hormones, which play an important role in growth and development. Previously we demonstrated its positive influence on oxidative stress parameters in normal human fibroblasts, therefore we decided to investigate its activity in cancer cells. MCF-7 breast cancer cell line was chosen as an experimental model because of proved association between the consumption of dietary fat and the incidence of breast cancer. TA cytotoxicity and its effects on MCF-7 cells proliferation, viability, apoptosis/necrosis, thiol group content, lipid peroxidation, reduced/oxidized glutathione (GSH/GSSG) and ROS (reactive oxygen species) content was examined. The results show a significant effect of TA on tested parameters. TA caused a decrease in cells proliferation and viability, GSH/GSSG ratio and thiol group content. It increases caspase 7 activity, membrane lipid peroxidation and ROS content, simultaneously reducing breast cancer cell growth through oxidative stress influence on apoptosis. The present findings reveal that TA exhibits multiple and complex activity in MCF-7 breast cancer cells and it exhibits potential anticancer properties and tumor preventive activity.

32P - MicroRNA in combination with HER2-targeting drugs reduces breast cancer cell viability in vitro

32P - MicroRNA in combination with HER2-targeting drugs reduces breast cancer cell viability in vitro

A mutual activation loop between the Ca2+-activated chloride channel TMEM16A and EGFR/STAT3 signaling promotes breast cancer tumorigenesis.

The Ca2+-activated chloride channel TMEM16A (anoctamin 1) is overexpressed in breast cancer. It remains unclear how TMEM16A overexpression plays a role in carcinogenesis in breast cancer. In this study, we found that high TMEM16A expression in combination with high EGFR or STAT3 expression was significantly associated with shorter overall survival in ER-positive breast cancer patients without tamoxifen treatment, and longer overall survival in patients with tamoxifen treatment. EGFR/STAT3 signaling activation by EGF promoted TMEM16A expression, and TMEM16A overexpression activated EGFR/STAT3 signaling in breast cancer cells. Both in vitro and in animal studies showed that TMEM16A overexpression promoted, and TMEM16A knockdown inhibited breast cancer cell proliferation and tumor growth. In addition, TMEM16A overexpression-induced cell proliferation was blocked by EGFR/STAT3 inhibitors, and TMEM16A knockdown reduced EGF-induced proliferation and tumorigenesis in breast cancer. Furthermore, inhibition of TMEM16A channel function effectively reduced breast cancer cell proliferation, especially in combination with EGFR inhibitors. Our findings identify a mutual activation loop between TMEM16A and EGFR/STAT3 signaling, which is important for breast cancer proliferation and growth. TMEM16A inhibition may represent a novel therapy for EGFR-expressing breast cancer.

Oligonucleotide-directed STAT3 alternative splicing switch drives anti-tumorigenic outcomes in MCF10 human breast cancer cells

Signal transducer and activator of transcription 3 (STAT3), a transcription factor responsive to the activation of cytokine receptors, is known for its oncogenic actions. Whilst STAT3α is the predominant spliceform in most tissues, alternative splicing of the STAT3 gene can generate a shorter STAT3β spliceform. Redirecting splicing to enhance STAT3β levels can result in tumor suppression in vivo, and so we evaluated the cellular basis underlying the anti-tumorigenic properties of STAT3β. To investigate the impact of increased STAT3β levels in cancer cells, we implemented a Morpholino-based antisense oligonucleotide strategy to modulate STAT3 spliceform expression in the MCF10CA1h cancer cells of the MCF10 series of human breast cancer cells. We employed nonsense-mediated decay (NMD) oligonucleotides and STAT3α-to-β expression switching (SWI) oligonucleotides to successfully induce STAT3 knockdown and redirect alternative splicing to increase STAT3β levels in MCF10CA1h cells, respectively. Importantly, assessment of the impacts of STAT3 splicing modulation on tumor cell biology showed that the SWI treatment significantly reduced MCF10CA1h cell growth, viability, and migration, whereas NMD treatment was without significant impact, although neither NMD nor SWI oligonucleotides significantly inhibited MCF10CA1h cell invasion through a semi-solid matrix. In conclusion, our data demonstrate that reduced breast cancer cell growth, viability and migration, but not invasion, follow the redirection of STAT3α-to-β expression switching to favour STAT3β expression.

Transfection with p21 and p53 tumor suppressor plasmids suppressed breast tumor growth in syngeneic mouse model

Treatment of breast cancer by delivering important tumor suppressor plasmids is a promising approach in the field of clinical medicine. We transfected p21 and p53 tumor suppressor plasmids, into different breast cancer cell lines using inorganic nanoparticles (NPs) of carbonate apatite to evaluate the effect of gene expression on reducing breast cancer cell growth. In triple negative MDA-MB-231 breast cancer cell line, the cytotoxicity assay upon combined delivery of p21 and p53 plasmid loaded NPs showed significant decrease in cell growth compared to distinct p21 or p53 treatments. Also, in MCF-7 and 4T1 cell lines, significant reduction in cellular growth was observed following p21 or p53 plasmid transfection. The Western blot data showed that NP loaded p21 and p53 transgene delivery in MDA-MB-231 cell line resulted in a noteworthy decrease in phosphorylated form of MAPK protein of MAPK/ERK pathway. The in vivo studies in syngeneic breast cancer mouse model demonstrated that the rate of growth and final tumor volume were reduced to a greater extent in mice that received intravenous injection of p21 + NP and p53 + NP therapeutics.

Citron kinase (CIT-K) promotes aggressiveness and tumorigenesis of breast cancer cells in vitro and in vivo: preliminary study of the underlying mechanism

ObjectivesCitron kinase (CIT-K), as a key Rho effector, functions to maintain proper structure of the midbody during cell mitosis. This study assessed CIT-K expression and its role in breast cancer cells.MethodsParaffin-embedded breast cancer and para-tumor tissues from 43 invasive breast cancer patients and 33 normal mammary glands were collected for immunohistochemistry. CIT-K expression knockdown was achieved using lentivirus carrying CIT-K shRNA in a wide range of breast cancer cell lines. Cells were then subjected to Western blot, qRT-PCR, cell proliferation, colony formation, transwell, and flow cytometric assays. The tumorigenicity of CIT-K knocked-down breast cancer cells was assessed using the nude mouse xenograft assay. Microarray analysis was performed to elucidate the underlying gene regulation after CIT-K silencing.ResultsCIT-K protein was overexpressed in breast cancer tissues, which is associated with advanced tumor stage, HER-2 expression and Ki-67 expression, whereas knockdown of CIT-K expression reduced breast cancer cell proliferation and colony formation, but promoted tumor cell apoptosis and cell-cycle arrest. Knockdown of CIT-K expression also inhibited breast cancer cell migration and invasion capacity. Moreover, CIT-K knockdown suppressed the tumorigenicity of breast cancer cells in nude mice. Molecularly, the expression of a variety of signaling genes, such as cyclin D1, EGFR, JAK1, TGF-α, PTK2, RAF1, RALB, SOS1, mTOR, and PTGS2, were altered after CIT-K knockdown.ConclusionsThis study demonstrated that CIT-K is associated with aggressive breast cancer behavior and targeting CIT-K may be a novel strategy for the future control of breast cancer.

Highlights of This Issue

The transcription factor RUNX1, represses the breast cancer stem cell (BCSC) phenotype and suppresses tumor growth in vivo. BCSCs sorted from pre-malignant breast cancer cells exhibit decreased RUNX1 levels, while ectopic expression of RUNX1 suppresses tumorsphere formation and reduces the BCSC population. Ectopic expression of RUNX1 reduces breast cancer cell migration, invasion, and in vivo tumor growth. RUNX1 suppresses tumor growth by repressing cancer stem cell activity and directly inhibiting Zeb1 expression. Clinical findings reveal the highest RUNX1 levels in normal mammary epithelial cells and low RUNX1 expression in tumors is associated with poor patient survival.NUT Carcinoma (NC) is a rare, distinctly aggressive subtype of squamous carcinoma driven by NUT-fusion oncoproteins, most commonly BRD4-NUT, and there is currently no effective therapy. The current Rapid Impact, discovers a novel NUT fusion, ZNF592-NUT, from a young patient with NC arising in pelvic bone. In the more typical context of BRD4-NUT-driven NC, it was determined that ZNF592, along with its known “Z4” complex interactors (ZNF532 and ZMYND8) associate with BRD4-NUT and are required to sustain NC, but not non-NC, growth and viability. This study establishes the oncogenic role of Z4 units in NUT carcinoma, offering potential new targeted therapeutic strategies.Ubiquitin-specific protease 6 (USP6) is the key pathogenic agent in several benign tumors, however its role in malignant entities has not been examined. Henrich and colleagues describe a role for USP6 in Ewing sarcoma (ES), a highly lethal pediatric bone cancer. While USP6 does not enhance ES transformation, it is associated with an interferon (IFN) response in both cultured ES cells and clinical specimens. Further, USP6 renders ES cells exquisitely sensitive to exogenous IFNs, with Type I IFN inducing apoptosis specifically in USP6-positive ES cells through induction of the pro-apoptotic ligand TRAIL. These findings raise the possibility of using USP6 as a biomarker for IFN treatment of ES.β-catenin suppressors tightly regulate the transcriptional activity of the activated Wnt/β-catenin pathway during both normal development and cancer. Here, a novel β-catenin transcription suppressor with a FLYWCH/Zn-finger DNA-binding domain, called “FLYWCH1” is identified. The FLYWCH1 protein directly binds to nuclear β-catenin and rearranges its transcriptional activity to selectively block the expression of specific target genes associated with colorectal cancer cell-cell adhesion and migration. This study, for the first time, characterizes and describes a possible anti-metastasis and tumor suppressive role of FLYWCH1 in the context of the Wnt/β-catenin pathway.

Mapping the genetic basis of breast microcalcifications and their role in metastasis

Breast cancer screening and early stage diagnosis is typically performed by X-ray mammography, which detects microcalcifications. Despite being one of the most reliable features of nonpalpable breast cancer, the processes by which these microcalcifications form are understudied and largely unknown. In the current work, we have investigated the genetic drivers for the formation of microcalcifications in breast cancer cell lines, and have investigated their involvement in disease progression. We have shown that stable silencing of the Osteopontin (OPN) gene decreased the formation of hydroxyapatite in MDA-MB-231 breast cancer cells in response to osteogenic cocktail. In addition, OPN silencing reduced breast cancer cell migration. Furthermore, breast cancer cells that had spontaneously metastasized to the lungs in a mouse model of breast cancer had largely elevated OPN levels, while circulating tumor cells in the same mouse model contained intermediately increased OPN levels as compared to parental cells. The observed dual roles of the OPN gene reveal the existence of a direct relationship between calcium deposition and the ability of breast cancer cells to metastasize to distant organs, mediated by common genetic factors.

Abstract 36: Novel age-related tumor promoting and inhibiting genes in breast cancer

Abstract During aging, besides genetic alterations, genes with altered expression may promote breast cancer development. Using linear regression modeling, we identified 148 up-regulated and 189 down-regulated genes during aging, by analyzing the whole transcriptome profiling data of matched normal tissues from 82 female patients with age and menopausal status available from The Cancer Genome Atlas data. We also compared matched tumor and normal samples, 3356 up-regulated and 3124 down-regulated genes were identified to be affected by tumorigenesis. Overlapping of tumorigenesis-associated genes with age-dependent genes resulted in 14 up-regulated and 24 down-regulated genes with both age and tumorigenesis. These genes were significantly predictive in relapse free survival, indicative of their potential tumor promoting or suppressive functions respectively. To test this hypothesis, we selected two up-regulated genes-DYNLT3 and P4HA3, and two down-regulated genes-ALX4 and WDR86 to investigate their function in controlling breast cancer malignancy because they are novel genes to breast cancer. We found that knockdown of DYNLT3 or P4HA3, and overexpression of ALX4, significantly reduced breast cancer cell proliferation, migration and colony forming capacity in soft agar, while overexpression of WDR86 did not show any inhibitory activity in breast cancer cells. Consistent with the in vitro data, knockdown of DYNLT3, P4HA3 and overexpression of ALX4 inhibited tumor growth and lung metastasis when breast cancer cells were orthotopically implanted in mice, whereas such inhibition was not observed in mice when WDR86-overexpressing breast cancer cells were implanted. Taken together, our results support that some age-related genes harbor tumor promoting or inhibiting functions. Thus, proper modulation of their expression has potential to prevent or slow down the progression of breast cancer. Citation Format: Bingzhi Wang, Xiang Gu, Haiyan Zhu, Luzhe Sun. Novel age-related tumor promoting and inhibiting genes in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 36.

Cancer Metastases to Bone: Concepts, Mechanisms, and Interactions with Bone Osteoblasts.

The skeleton is a unique structure capable of providing support for the body. Bone resorption and deposition are controlled in a tightly regulated balance between osteoblasts and osteoclasts with no net bone gain or loss. However, under conditions of disease, the balance between bone resorption and deposition is upset. Osteoblasts play an important role in bone homeostasis by depositing new bone osteoid into resorption pits. It is becoming increasingly evident that osteoblasts additionally play key roles in cancer cell dissemination to bone and subsequent metastasis. Our laboratory has evidence that when osteoblasts come into contact with disseminated breast cancer cells, the osteoblasts produce factors that initially reduce breast cancer cell proliferation, yet promote cancer cell survival in bone. Other laboratories have demonstrated that osteoblasts both directly and indirectly contribute to dormant cancer cell reactivation in bone. Moreover, we have demonstrated that osteoblasts undergo an inflammatory stress response in late stages of breast cancer, and produce inflammatory cytokines that are maintenance and survival factors for breast cancer cells and osteoclasts. Advances in understanding interactions between osteoblasts, osteoclasts, and bone metastatic cancer cells will aid in controlling and ultimately preventing cancer cell metastasis to bone.

Lithocholic acid, a bacterial metabolite reduces breast cancer cell proliferation and aggressiveness

Our study aimed at finding a mechanistic relationship between the gut microbiome and breast cancer. Breast cancer cells are not in direct contact with these microbes, but disease could be influenced by bacterial metabolites including secondary bile acids that are exclusively synthesized by the microbiome and known to enter the human circulation. In murine and bench experiments, a secondary bile acid, lithocholic acid (LCA) in concentrations corresponding to its tissue reference concentrations (< 1 μM), reduced cancer cell proliferation (by 10–20%) and VEGF production (by 37%), aggressiveness and metastatic potential of primary tumors through inducing mesenchymal-to-epithelial transition, increased antitumor immune response, OXPHOS and the TCA cycle. Part of these effects was due to activation of TGR5 by LCA. Early stage breast cancer patients, versus control women, had reduced serum LCA levels, reduced chenodeoxycholic acid to LCA ratio, and reduced abundance of the baiH (7α/β-hydroxysteroid dehydroxylase, the key enzyme in LCA generation) gene in fecal DNA, all suggesting reduced microbial generation of LCA in early breast cancer.

Function of microRNA‑141 in human breast cancer through cytotoxic CD4+ T cells regulated by MAP4K4 expression.

The present study investigated the anti‑cancer effect of microRNA (miRNA)‑141 on apoptosis rate of breast cancer cells and the possible underlying mechanism. In patients with breast cancer, the expression of miRNA‑141 was downregulated. Overexpression of miRNA‑141 reduced breast cancer cell growth, inhibited the expression of cyclooxygenase‑2 (COX‑2), prostaglandin E2 (PGE2) and tumor necrosis factor (TNF)‑α, and increased the expression levels of interleukin (IL)‑10. However, downregulation of miRNA‑141 resulted in upregulation of COX‑2, PGE2 and TNF‑α expression levels, and an inhibition of IL‑10. Overexpression of miRNA‑141 suppressed mitogen‑activated protein kinase kinase kinase kinase 4 (MAP4K4) protein expression. Downregulation of miRNA‑141 markedly upregulated MAP4K4 protein expression in MCF‑7 cells. Promotion of MAP4K4 protein expression reduced the effects of miRNA‑141 on the toxicity of CD4+ T cells on breast cancer cells. The results of the present study indicated that miRNA‑141may cause anti‑tumor effects in human breast cancer cells via cytotoxic CD4+ T cells.

Doxorubicin resistance in breast cancer cells is mediated by extracellular matrix proteins

BackgroundCancer cell resistance to therapeutics can result from acquired or de novo-mediated factors. Here, we have utilised advanced breast cancer cell culture models to elucidate de novo doxorubicin resistance mechanisms.MethodsThe response of breast cancer cell lines (MCF-7 and MDA-MB-231) to doxorubicin was examined in an in vitro three-dimensional (3D) cell culture model. Cells were cultured with Matrigel™ enabling cellular arrangements into a 3D architecture in conjunction with cell-to-extracellular matrix (ECM) contact.ResultsBreast cancer cells cultured in a 3D ECM-based model demonstrated altered sensitivity to doxorubicin, when compared to those grown in corresponding two-dimensional (2D) monolayer culture conditions. Investigations into the factors triggering the observed doxorubicin resistance revealed that cell-to-ECM interactions played a pivotal role. This finding correlated with the up-regulation of pro-survival proteins in 3D ECM-containing cell culture conditions following exposure to doxorubicin. Inhibition of integrin signalling in combination with doxorubicin significantly reduced breast cancer cell viability. Furthermore, breast cancer cells grown in a 3D ECM-based model demonstrated a significantly reduced proliferation rate in comparison to cells cultured in 2D conditions.ConclusionCollectively, these novel findings reveal resistance mechanisms which may contribute to reduced doxorubicin sensitivity.

Suppressing glucose metabolism with epigallocatechin-3-gallate (EGCG) reduces breast cancer cell growth in preclinical models.

Numerous studies propose that epigallocatechin-3-gallate (EGCG), an abundant polyphenol in green tea, has anti-cancer properties. However, its mechanism of action in breast cancer remains unclear. This study investigated the capacity of EGCG to suppress breast cancer cell growth in vitro and in vivo, characterizing the underlying mechanisms, focusing on the effect of EGCG on glucose metabolism. EGCG reduced breast cancer 4T1 cell growth in a concentration- (10-320 μM) and time- (12-48 h) dependent manner. EGCG induced breast cancer apoptotic cell death at 24 h, as evidenced by annexin V/PI, caspase 3, caspase 8 and caspase 9 activation. Furthermore, EGCG affected the expression of 16 apoptosis-related genes, and promoted mitochondrial depolarization. EGCG induced autophagy concentration-dependently in 4T1 cells by modulating the levels of the autophagy-related proteins Beclin1, ATG5 and LC3B. Moreover, EGCG affected glucose, lactate and ATP levels. Mechanistically, EGCG significantly inhibited the activities and mRNA levels of the glycolytic enzymes hexokinase (HK), phosphofructokinase (PFK), and lactic dehydrogenase (LDH), and to a lesser extent the activity of pyruvate kinase (PK). In addition, EGCG decreased the expression of hypoxia-inducible factor 1α (HIF1α) and glucose transporter 1 (GLUT1), critical players in regulating glycolysis. In vivo, EGCG reduced breast tumor weight in a dose-dependent manner, reduced glucose and lactic acid levels and reduced the expression of the vascular endothelial growth factor (VEGF). In conclusion, EGCG exerts an anti-tumor effect through the inhibition of key enzymes that participate in the glycolytic pathway and the suppression of glucose metabolism.

Leukotriene Receptor Antagonists Inhibit Mitogenic Activity in Triple Negative Breast Cancer Cells

Despite a discovery of hormonal pathways regulating breast cancer, a definitive cure for the disease requires further identification of alternative targets that provide a hormone-independent support. Apart from their role in inflammatory diseases, cysteinyl leukotriene (CysLT) receptor antagonists (LTRAs) decrease the risk of lung cancer in asthma patients and inhibit tumor progression in several malignancies. In the present study, we evaluate the effects of two chemically different, clinically relevant LTRAs (montelukast and zafirlukast) in a triple negative breast cancer cell line, MDA-MB-231. We found that these two LTRAs reduced breast cancer cell viability in a dose-dependent manner with the 50% inhibitory concentration (IC50) between 5-10 μM. Although both LTRAs have several pharmacological properties in common, we noticed that montelukast mainly induced apoptosis, while zafirlukast mainly exerted its action on cell cycle. However, the precise mechanisms responsible for such different effects remain unclear. In summary, our results suggest that CysLT plays a role in proliferation and survivability of breast cancer cells in the absence of hormonal stimuli.