MCF10A Control Cells Research Articles

The A986S calcium sensing receptor variant supports the adaptation of breast cancer cells to high calcium — a novel paradigm in breast cancer progression

Breast cancer and other solid tumors that metastasize to bone are frequently accompanied by a progressive increase in circulating calcium as the disease becomes more malignant. The increase in circulating calcium not only disrupts systemic calcium homeostasis but also alters the ability of cells to sense slight changes in extracellular Ca2+ via the ubiquitous calcium sensing receptor (CaSR). Of the CASR polymorphisms at rs1801725 (p.A986S), rs1801726 (p.Q1011E), and rs1042636 (p.R990G) in exon 7 of the receptor, previous studies have shown that only the A986S CaSR variant is associated with calcium in breast, prostate and skin cancers. In this study, we assessed if exon 7 inactivating A986S (AS-CaSR) and Q1011E (QE-CaSR) variants of the receptor influence the survival of breast tumor cells at higher Ca2+. We generated isogenic HEK293T and BT-549 cells expressing these CaSR variants and carried out bulk RNA sequencing of high Ca2+ adapted control and breast cancer cells. CaSR expression was detected by western blotting using anti-flag M2 (Sigma) antibody. By using phospho-ERK1/2 as the readout, the activation of AS-CaSR required higher concentrations of Ca2+ (EC50 ~5.28 mM) compared to the QE-CaSR (EC50 of ~3.81 mM) and the wild type (WT-CaSR; EC50 ~3.69 mM) receptor. When the CaSR variants transfected cells initially cultured at 7.5 mM for 6 days, and then sub-cultured in medium containing 7.5 to 20 mM Ca2+, the viability of empty vector control and WT-CaSR transfected cells strongly decreased at Ca2+ levels beyond 7.5 mM and these cells were mostly necrotic at ≥15 mM Ca2+. The QE-CaSR variant transfected cells on the other hand exhibited limited cell death beyond 10 mM Ca2+, while the surviving colonies of the AS-CaSR variant were viable at up to 15 mM Ca2+ with invasive tendencies. Analysis of differentially expressed genes in high Ca2+ adapted mesenchymal-like BT-549 and epithelial MDA-MB-468 breast cancer cells compared to MCF10A control cells revealed a small set of differentially expressed genes that were significantly associated with relapse free survival of basal-like breast cancer patients. Among these genes are ligands and negative regulators of the WNT/FZD pathway. Our data suggest that the A986S-CaSR variant with reduced sensitivity to Ca2+ supported adaptation of TNBC cells at high Ca2+, and that high Ca2+ adaptation of breast cancer cells may be mediated via a panel of high Ca2+ inducible genes with implications in bone metastasis. This study is supported by NIH SC1GM139814, T32AI007281, T32GM144927, T32HL007737; and the American Cancer Society. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The cytotoxic effects of indoleamine 2, 3-dioxygenase inhibitors on triple negative breast cancer cells upon tumor necrosis factor α stimulation.

Overexpressed indoleamine 2,3-dioxygenase (IDO) has been observed in many types of cancer and plays an essential role in the tumor microenvironment through immune cells function. In our study, the therapeutic potentials of two different IDO inhibitors (Epacadostat [EPA] and 1-methyl-L-tryptophan [L-1MT]) in triple-negative breast cancer (TNBC) cells were assessed with and without tumor necrosis factor-α (TNF-α) stimulation. The anticancer activity of EPA and L-1MT alone and in combination with TNF-α was analyzed by WST-1, annexin V, cell cycle analysis, and acridine orange/ethidium bromide staining. In addition, the relationship between IDO1 and programmed death-ligand 1 (PD-L1) expressions in TNBC cells upon treatment with IDO inhibitors was evaluated by reverse transcription-polymerase chain reaction analysis. SPSS 22.0 was conducted for statistical analysis. The one-way analysis of variance with Tukey's multiple comparison test was performed for multiple groups. Independent (unpaired) t -test was used for the comparison of two groups. EPA and L-1MT alone significantly suppressed the TNBC cell viability through the induction of apoptotic cell death and G0/G1 arrest (P < 0.05). TNF-α alone induced the overexpression of IDO1 and PD-L1 in TNBC cells compared with MCF-10A control cells. However, IDO inhibitors significantly inhibited overexpressed IDO1 mRNA levels. Furthermore, EPA alone and co-treated with TNF-α suppressed the mRNA level of PD-L1 in TNBC cells. Therefore, TNF-α stimulation enhanced the therapeutic effects of IDO inhibitors on TNBC. Our findings showed that the efficacy of IDO inhibitors was mediated by pro-inflammatory cytokine. However, different molecular signaling pathways are associated with pro-inflammatory cytokines production, and the expression of IDO1 and PD-L1 calls for further investigations.

Relative Expression of Voltage‐Gated Sodium Channels in Cancerous and Noncancerous Cells during the Cell Cycle

Upregulation of voltage gated sodium channels (VGSCs) is the target for many novel carcinoma therapies. The majority carcinomas over-express voltage gated sodium channels, including breast cancers, lung cancers and mesotheliomas. We found variability in VGSC expression in clonal cancer cell lines. There is some limited electrophysiologic evidence that there is an upregulation of VGSCs during cell division. We hypothesized that the doubling of DNA during the cell cycle would also double the cell surface expression of VGSC protein compared to nondividing cells. We tested this hypothesis using flow cytometry with the fluorescent DNA label, propidium iodide and a conjugated panspecific-VGSC antibody. For lung cells, we compared A549 lung cancer cells with MRC5 control cell line and KLN 205 mouse cancer line. We compared H28 mesothelioma cells with MeT-5a normal pleural effusion cells and AB1 mouse mesothelioma cells. For breast cancer, we compared MDA-MB 231 breast cancer cells, MCF 10a control cells, and 4T1 mouse breast cancer cells. We found that, amoungst all the cell lines, there is between 1.86 and 2.15 more VGSCs expressed in dividing cells than in nondividing cells. Additionally, in cells imaged with confoccal microscopy, VGSCs were also shown in abundance at the leading ends of cells in anaphase. With this information we can more effectively target novel cancer therapies and thus improve the efficacy in carcinomas that overexpress VGSCs.

Regulation of valproic acid induced EMT by AKT/GSK3β/β-catenin signaling pathway in triple negative breast cancer.

Valproic acid (VPA) is a selective histone deacetylation (HDAC) inhibitor and exerts anti-cancer properties in different types of cancer. The epithelial-to-mesenchymal transition (EMT) mediating by different signaling cascade can be a potential target in aggressive human cancers. Therefore, we aimed to clarified the unravel relationship between AKT/GSK3β/β-catenin signalling pathway and VPA-induced EMT in triple negative breast cancer (TNBC). The cytotoxicity of VPA in MDA-MB-231 TNBC and MCF-10A control cells was evaluated. Alterations in the expression levels of Snail, E-cadherin, AKT, GSK3β, β-catenin were analyzed by RT-PCR. Additionally, Annexin V, cell cycle and wound healing assays were performed. Our results showed that VPA remarkably inhibited the growth of TNBC cell and triggered apoptotic cell death through G0/G1 arrest. Furthermore, VPA increased cell migration and activated the EMT process through significantly increasing Snail expression and in turn downregulation of E-cadherin and GKS3β levels. However, the level of AKT and β-catenin was reduced after treatment of VPA. Our data showed that VPA induced EMT process and cell migration in TNBC cells. However, AKT/GSK3β/β-catenin signaling pathway did not mediate EMT activation.

An efficient synthetic route to l-γ-methyleneglutamine and its amide derivatives, and their selective anticancer activity.

In cancer cells, glutaminolysis is the primary source of biosynthetic precursors, fueling the TCA cycle with glutamine-derived α-ketoglutarate. The enhanced production of α-ketoglutarate is critical to cancer cells as it provides carbons for the TCA cycle to produce glutathione, fatty acids, and nucleotides, and contributes nitrogens to produce hexosamines, nucleotides, and many nonessential amino acids. Efforts to inhibit glutamine metabolism in cancer using amino acid analogs have been extensive. l-γ-Methyleneglutamine was shown to be of considerable biochemical importance, playing a major role in nitrogen transport in Arachis and Amorpha plants. Herein we report for the first time an efficient synthetic route to l-γ-methyleneglutamine and its amide derivatives. Many of these l-γ-methyleneglutamic acid amides were shown to be as efficacious as tamoxifen or olaparib at arresting cell growth among MCF-7 (ER+/PR+/HER2-), and SK-BR-3 (ER-/PR-/HER2+) breast cancer cells at 24 or 72 h of treatment. Several of these compounds exerted similar efficacy to olaparib at arresting cell growth among triple-negative MDA-MB-231 breast cancer cells by 72 h of treatment. None of the compounds inhibited cell growth in benign MCF-10A breast cells. Overall, N-phenyl amides and N-benzyl amides, such as 3, 5, 9, and 10, arrested the growth of all three (MCF-7, SK-BR-3, and MDA-MB-231) cell lines for 72 h and were devoid of cytotoxicity on MCF-10A control cells; N-benzyl amides with an electron withdrawing group at the para position, such as 5 and 6, inhibited the growth of triple-negative MDA-MB-231 cells commensurate to olaparib. These compounds hold promise as novel therapeutics for the treatment of multiple breast cancer subtypes.

PET Imaging of L-Type Amino Acid Transporter (LAT1) and Cystine-Glutamate Antiporter (xc-) with [18F]FDOPA and [18F]FSPG in Breast Cancer Models.

The present study describes the analysis of amino acid transporters ASCT1, ASCT2, LAT1, and xc- in breast cancer under normoxic and hypoxic conditions. [18F]FDOPA-PET and [18F]FSPG-PET were used as imaging biomarkers to probe L-type amino acid transporter (LAT1) and cystine-glutamate antiporter (xc-) in breast cancer models. LAT1 and xc- transporters were studied under normoxic and hypoxic conditions with radiotracers [18F]FDOPA and [18F]FSPG in estrogen receptor-positive (ER+) MCF7 and triple-negative MDA-MB231 cells and in human mammary epithelial MCF10A control cells. Protein expression was analyzed using Western blot and immunohistochemistry. ASCT1 protein expression levels were comparable in all three cell lines, while noticeable ASCT2 expression levels were only found in MCF10A control cells. Higher LAT1 protein expression was detected in ER+ MCF7 cells. High xc- protein expression levels were detected in MDA-MB231 cells. Uptake of [18F]FDOPA through LAT1 was significantly higher in MCF7 versus MDA-MB231 cells, while the uptake of [18F]FSPG through xc- resulted in the opposite confirming expression and functional differences for both amino acid transporters in different breast cancer models. Hypoxia significantly increased [18F]FDOPA uptake in MCF7 cells and [18F]FSPG uptake in MDA-MB231 cells. In vivo PET imaging revealed substantially higher tumor uptake of [18F]FDOPA in MCF7 tumors as well as [18F]FSPG uptake in MDA-MB231 tumors confirming differences detected in vitro. ER+ breast cancer cells express higher levels of amino acid transporter LAT1, whereas triple-negative breast cancer cells express more xc-. Cellular uptake and PET imaging experiments with [18F]FDOPA and [18F]FSPG confirmed functional LAT1 and xc- expression profiles. There was initial evidence that hypoxia regulates the function of both amino acid transporters in breast cancer. The results further indicated that [18F]FDOPA and [18F]FSPG are suitable radiotracer to distinguish between ER+ and triple-negative breast cancer types.

Ullmann-type C-Se Cross-Coupling in the Hydantoin Family: Synthesis, Mechanistic Studies, and Tests of Biological Activity.

An attractive strategy for C-Se bond formation by Ullmann-type copper(I)-promoted cross-coupling is developed. A wide range of aryliodides reacts with various disubstituted 2-selenohydantoins under mild conditions and provides Se-arylated imidazolines in moderate to high yields. Computational mechanistic studies show the oxidative addition/intramolecular reductive elimination likely to be the lowest-energy pathway. Cytotoxic activity of all 43 reaction products has been tested in vitro against MCF7 and A549 cancer cell lines with VA13 and MCF10a control cells.

Talazoparib Loaded Solid Lipid Nanoparticles: Preparation, Characterization and Evaluation of the Therapeutic Efficacy In vitro.

In the present work, we report for the first time the therapeutic potential of talazoparib (BMN 673)-SLNs for the treatment of BRCA1 deficient Triple Negative Breast Cancer (TNBC). BMN 673-SLNs were produced by hot-homogenization technique and then characterized. The cytotoxic and apoptotic effects of BMN 673-SLNs compared with BMN 673 were determined on HCC1937BRCA1-/-, HCC1937-R resistant TNBC and MCF-10A control cell lines. BMN 673- SLNs were found to have reduced particle size (219.5 ± 1.45 nm) and thus more stable (-28.4 ± 2.52 mV) than BMN 673 (1652 ± 2.46 nm and -18.6 ± 0.45 mV) at 4°C. In vitro cell line studies demonstrated that BMN 673-SLNs showed significant cytotoxic effects on HCC1937 (29.8%) and HCC1937-R cells (35.7%) at 10 nM for 12 days compared with BMN 673 (HCC1937 cells: 34.0% and HCC1937-R cells: 93.8% at 10 nM for 12 days) (p<0.05). Additionally, BMN 673-SLNs (40.1%) reduced the toxicity of BMN 673 (53.1%) on MCF-10A control cells thanks to unique physical properties. The apoptotic rates in the 10 nM BMN 673-SLNs treatment (88.78% and 85.56%) for 12 days were significantly higher than those in 10 nM BMN 673 (82.6% and 25.86%) for 12 days in HCC1937 and HCC1937-R cells, respectively (p<0.01). Furthermore, these effects were consistent with the findings of colony formation, wound healing and calcein accumulation analysis. In conclusion, the therapeutic potential of BMN 673-SLNs provides a promising chemotherapeutic strategy for the treatment of drugresistant TNBC.

Mitochondrial autoimmunity and MNRR1 in breast carcinogenesis

BackgroundAutoantibodies function as markers of tumorigenesis and have been proposed to enhance early detection of malignancies. We recently reported, using immunoscreening of a T7 complementary DNA (cDNA) library of breast cancer (BC) proteins with sera from patients with BC, the presence of autoantibodies targeting several mitochondrial DNA (mtDNA)-encoded subunits of the electron transport chain (ETC) in complexes I, IV, and V.MethodsIn this study, we have characterized the role of Mitochondrial-Nuclear Retrograde Regulator 1 (MNRR1, also known as CHCHD2), identified on immunoscreening, in breast carcinogenesis. We assessed the protein as well as transcript levels of MNRR1 in BC tissues and in derived cell lines representing tumors of graded aggressiveness. Mitochondrial function was also assayed and correlated with the levels of MNRR1. We studied the invasiveness of BC derived cells and the effect of MNRR1 levels on expression of genes associated with cell proliferation and migration such as Rictor and PGC-1α. Finally, we manipulated levels of MNRR1 to assess its effect on mitochondria and on some properties linked to a metastatic phenotype.ResultsWe identified a nuclear DNA (nDNA)-encoded mitochondrial protein, MNRR1, that was significantly associated with the diagnosis of invasive ductal carcinoma (IDC) of the breast by autoantigen microarray analysis. In focusing on the mechanism of action of MNRR1 we found that its level was nearly twice as high in malignant versus benign breast tissue and up to 18 times as high in BC cell lines compared to MCF10A control cells, suggesting a relationship to aggressive potential. Furthermore, MNRR1 affected levels of multiple genes previously associated with cancer metastasis.ConclusionsMNRR1 regulates multiple genes that function in cell migration and cancer metastasis and is higher in cell lines derived from aggressive tumors. Since MNRR1 was identified as an autoantigen in breast carcinogenesis, the present data support our proposal that both mitochondrial autoimmunity and MNRR1 activity in particular are involved in breast carcinogenesis. Virtually all other nuclear encoded genes identified on immunoscreening of invasive BC harbor an MNRR1 binding site in their promoters, thereby placing MNRR1 upstream and potentially making it a novel marker for BC metastasis.

Abstract P2-06-19: The effect of UBE2C expression on intrinsic chemosensitivity in breast cancer cell lines

Abstract Background: The ubiquitin-proteasome pathway plays a crucial role in cancer-related processes by inducing cell cycle arrest through the degradation of mitotic cyclins and other cell cycle regulatory proteins. We recently showed that elevated levels of ubiquitin-conjugating enzyme E2C (UBE2C) were associated with aggressive tumor features and unfavorable clinical outcome in breast carcinoma (BC). UBE2C suppression has been achieved using the FDA-approved proteasome inhibitor bortezomib (VELCADE®) in colorectal carcinoma, but little is known about the efficacy of UBE2C-targeted therapy with proteasome inhibitors in breast cancer. Methods: Cell viability assays were used to determine the intrinsic chemosensitivity of five BC cell lines (MCF-7, MDA-MB-436, HCC38, HCC1395, and ZR-75-30; stratified by UBE2C expression and ER status) and the MCF-10A epithelial cell line to proteasome inhibitors (n=8), mitosis inhibitors (n=2), and platinum agents (n=3). UBE2C expression analysis was performed using quantitative real-time PCR and Western blot. IC50 values and growth inhibition metrics (GR50 and GRmax) were calculated for each compound to determine drug potency and efficiency after 24 hour treatment. Proteasome activity was assessed using bortezomib-treated cells. Results: Heterogeneous UBE2C expression levels were found in the different cell lines, with higher UBE2C levels in ER-negative BC cell lines (HCC38, HCC1395, MDA-MB-436) than ER-positive BC (MCF-7 and ZR-75-30) and MCF-10A control cells (ER-negative). Proteasome inhibition levels close to 50% and 100% were seen in all cell lines after 10 nM and 100 - 1000 nM bortezomib, respectively. As expected, bortezomib blocked cell cycle progression by inducing G2/M phase arrest in HCC38 cells. Due to differences in cell growth rates, calculation of the IC50 value was an ineffective method to determine drug potency. In contrast, the normalized growth rate inhibition method with GR50 and GRmax values demonstrated a correlation between sensitivity to proteasome inhibitors in ER-negative BC cell lines and high UBE2C expression levels. However, MDA-MB-436 cells (GR50, range 1.8-286.1 nM; GRmax, range -0.42- -0.93) were generally less sensitive to proteasome inhibitors than HCC38 cells (GR50, range 8.2-936.8 nM; GRmax, range -0.97- -0.99) though both cell lines were ER-negative, which was possibly due to the lower expression of UBE2C in MDA-MB-436 cells. Compared with the other tested drugs, no cell line was sensitive to the mitosis inhibitors and platinum agents were most effective in HCC38 cells. Conclusions: Taken together, these findings suggest an association between UBE2C expression and response to proteasome inhibition, regardless of ER status. Citation Format: Parris TZ, Larsson P, Biermann J, Engqvist H, Werner-Rönnerman E, Kovács A, Karlsson P, Helou K. The effect of UBE2C expression on intrinsic chemosensitivity in breast cancer cell lines [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-06-19.

BMN 673 (talazoparib): A potent PARP inhibitor for triple negative breast cancer with different genetic profile.

The objective of the present study was to elucidate the effect of BMN 673 (talozoparib) on BRCA1 mutant (HCC1937) and wild-type (MDA-MB-231) triple negative breast cancer (TNBC). The in vitro cytotoxicity results indicated that BMN 673 had considerable inhibitory effects on HCC1937 and MDA-MB-231 cell lines by inducing apoptosis, multicaspase activity, G2/M arrest, and altering the expression levels of apoptosis-related genes (P < 0.01). Additionally, BMN 673 indicated no toxicity on MCF-10A control cells until a certain concentration and incubation time. However, BMN 673, a novel and selective poly ADP ribose polymerase inhibitor, was more potent in TNBC cells bearing BRCA1 mutant than those with wild-type BRCA1. In conclusion, our study, for the first time, demonstrated a molecular mechanism of the induction of apoptosis by BMN 673 in TNBC with different genetic profile. However, further investigations regarding the exact molecular mechanisms underlying BMN 673-inducing apoptotic death and gene-cell line associations are required.

Solid lipid nanoparticles: Reversal of tamoxifen resistance in breast cancer

The objective of the present study was to investigate the effect of tamoxifen (Tam) loaded solid lipid nanoparticles (SLNs) on MCF7 Tam-resistant breast cancer cells (MCF7-TamR). Tam-SLNs were produced by the hot homogenization method. The characterization studies of Tam-SLNs demonstrated good physical stability with small particle size. The in vitro cytotoxicity results showed that Tam-SLNs enhanced the efficacy of Tam and reversed the acquired Tam resistance by inducing apoptosis, altering the expression levels of specific miRNA and the related apoptosis-associated target-genes in both MCF7 and MCF7-TamR cells without damaging the MCF10A control cells (p < 0.05). In conclusion, we demonstrated a molecular mechanism of the induction of apoptosis by Tam-SLNs in MCF7 and MCF7-TamR cells, and thus, we demonstrated that Tam-SLNs were more effective than Tam. The present study suggests that the use SLNs may be a potential therapeutic strategy to overcome Tam-resistance in breast cancer for clinical use.

Pterostilbene down-regulates hTERT at physiological concentrations in breast cancer cells: Potentially through the inhibition of cMyc.

Human telomerase reverse transcriptase (hTERT) encodes the catalytic subunit of telomerase, which has been shown to be upregulated in many cancers. Pterostilbene is a naturally occurring stilbenoid and phytoalexin found primarily in blueberries that exhibits antioxidant activity and inhibits the growth of various cancer cell types. Therefore, the aim of this study was to determine whether treatment with pterostilbene, at physiologically achievable concentrations, can inhibit the proliferation of breast cancer cells and down-regulate the expression of hTERT. We found that pterostilbene inhibits the cellular proliferation of MCF-7 and MDA-MB-231 breast cancer cells in both a time- and dose-dependent manner, without significant toxicity to the MCF10A control cells. Pterostilbene was also shown to increase apoptosis in both breast cancer cell lines. Dose-dependent cell cycle arrest in G1 and G2/M phase was observed after treatment with pterostilbene in MCF-7 and MDA-231 cells, respectively. hTERT expression was down-regulated after treatment in both a time- and dose-dependent manner. Pterostilbene also reduced telomerase levels in both cell lines in a dose-dependent manner. Moreover, cMyc, a proposed target of the pterostilbene-mediated inhibition of hTERT, was down-regulated both transcriptionally and posttranscriptionally after treatment. Collectively, these findings highlight a promising use of pterostilbene as a natural, preventive, and therapeutic agent against the development and progression of breast cancer.

Anatolian honey is not only sweet but can also protect from breast cancer: Elixir for women from artemis to present.

Natural products with bioactive components are widely studied on various cancer cell lines for their possible cytotoxic effects, recently. Among these products, honey stands out as a valuable bee product containing many active phenolic compounds and flavonoids. Numerous types of multifloral honey and honeydew honey are produced in Turkey owing to its abundant vegetation. Therefore, in this study, we investigated the cytotoxic effects of particular tree-originated honeys from chestnut, cedar, pine, and multifloral honey on cell lines representing different types of the most common cancer of women, breast cancer, MCF7, SKBR3, and MDAMB-231, and fibrocystic breast epithelial cell line, MCF10A as a control. All honey samples were analyzed biochemically. The dose- (1, 2.5, 5, 7.5, and 10 µg/mL) and time (24th, 48th, and 72nd hours)-dependent effects of ethanol/water solutions of the honey samples were scrutinized. Cell viability/cytotoxicity was evaluated by the water soluble tetrazolium Salt-1 (WST-1) method. Apoptotic status was detected by Annexin V-PI assay using FACSCalibur. The statistical analysis was performed using GraphPad Prism 6 and the clustering data analysis with the R programming language. The biochemical analyses of the honey samples showed that the tree-originated honey samples contained more total phenolic compounds than the multifloral honey. Phenolic content of the honey types increases in order of multifloral, pine, cedar, and chestnut, respectively, which is compatible with their cytotoxic affectivity and dark color. In addition, the antioxidant capacity of the studied honey types was observed to increase in order of multifloral < pine < cedar ≅ chestnut. According to the WST-1 data, chestnut honey induced cytotoxicity over 50% on all the cell lines, including the control MCF10A cells, even with low doses (honey concentrations starting from 1 µg/mL) (P < 0.0001). Similarly, Cedar honey was observed to be the second most effective honey in this study. Cedar honey, with the dose of 1 µg/mL, was detected statistically highly significant on MCF10A, MCF7, and SKBR3. In contrast, pine honey showed dramatically significant cytotoxicity only on the MDAMB 231 cells with a 1 µg/mL dose at the same time point (P = 0.018). While pine honey caused an anticancer effect on the MCF-7 and SKBR3 cancer cell lines with a 2.5-5 µg/mL dose (P < 0.0001), like cedar and chestnut honeys, it increased the viability of the MCF10A control cells with the doses of 2.5-5 µg/mL. It only showed cytotoxicity with higher doses (10 µg/mL) on the MCF10A cell line (P < 0.0001). Moreover, we have observed that the multifloral and artificial honey samples were mostly ineffective or increased cell viability with the doses of 1-5 µg/mL. Apoptotic effects of the other honey samples on the MCF-7 cell line were found as chestnut> pine> cedar> multifloral in the Annexin V-propidium iodide (PI) analysis. Chestnut, cedar, and pine honey displayed a remarkably cytotoxic effect on breast cancer cell lines, MCF7, SKBR3, and even on the most aggressive MDAMB 231, representing the triple negative breast cancer, which lacks of targeted anticancer therapy. The chestnut and cedar honeys stand out to be the most cytotoxic on all cell lines, while pine honey was found to be the least toxic on control cells with appropriate toxicity on the cancer cells. © 2017 IUBMB Life, 69(9):677-688, 2017.

THE EFFECT OF SOLID LIPID NANOPARTICLES ON TAMOXIFEN-RESISTANT BREAST CANCER CELLS

&lt;p class="lead"&gt;To overcome the acquired Tamoxifen (Tam) resistance in Tam-resistant breast cancer cells without damaging normal cells, we have examined the therapeutic efficacy of Tam-loaded solid lipid nanoparticles (SLNs). Tam-loaded SLNs were produced by hot homogenization method. After characterization, &lt;em&gt;in vitro&lt;/em&gt; cytotoxic and apoptotic activity of Tam-SLNs were evaluated in MCF7, MCF7-TamR (Tam-resistant breast cancer cells) and MCF10A cells. Tam-SLNs had an average size nearly 300 nm and a zeta potential of approximately-40 mV. &lt;em&gt;In vitro&lt;/em&gt; cytotoxicity results showed that Tam-SLNs indicated the cytotoxic and apoptotic activity on MCF7 and MCF7-TamR cells. We found that MCF7-TamR cell viability was also suppressed significantly by Tam-SLNs and thus, Tam-SLNs could delay and overcome Tam-resistance (p&amp;lt;0.05). Furthermore, the Tam-SLNs did not induce apoptosis on MCF10A control cells. The lowest MCF10A cell viability was 83.0% whereas MCF7 and MCF7-TamR (R↔ and R↑) cells viability are reduced to 21.98%, 27.5% and 29.4% at 10 µM of Tam-SLNs, respectively (p&amp;lt;0.05). The obtained results were supported by apoptosis assays. SLNs-delivery system provided therapeutic efficacy to overcome Tam-resistance thanks to unique features of SLNs including small size, drug accumulation in the tumor site and controlled drug release. Therefore, Tam-SLNs may have therapeutic potential for the treatment of TAM-resistant breast cancer.&lt;/p&gt;

Repression of breast cancer cell growth by proteasome inhibitors in vitro: impact of mitogen-activated protein kinase phosphatase 1

Mitogen activated protein kinase phosphatase-1 (MKP-1) has emerged as an important protein mediating breast cancer oncogenesis and chemoresistance to cancer chemotherapies, especially proteasome inhibitors. In this in vitro study, we utilized the breast cancer epithelial cell lines MCF-7 and MDA-MB-231, in comparison to MCF-10A control cells, to examine the impact of MKP-1 on breast cancer cell growth and repression by proteasome inhibitors. We confirm that proteasome inhibitors MG-132 and bortezomib induce MKP-1 protein upregulation and we show that one of the ways in which bortezomib increases MKP-1 in breast cancer cells, in addition to inhibition of ubiquitin-proteasome system, is via upregulation of MKP-1 mRNA expression in p38 MAPK-mediated manner. Notably, these effects are specific to cancer cells, as bortezomib activated p38 MAPK and induced MKP-1 in MCF-7 and MDA-MB-231 breast cancer cells, but not in control cells (MCF-10A). We took a dual approach toward targeting MKP-1 to show that bortezomib-induced effects are enhanced. Firstly, treatment with the non-specific MKP-1 inhibitor triptolide reduces breast cancer cell growth and augments proteasome inhibitor-induced effects. Secondly, specific knock-down of MKP-1 with siRNA significantly repressed cell viability by reduced cyclin D1 expression, and enhanced repression of cancer cell growth by proteasome inhibitors. Taken together, these results indicate that removing the unwanted (MKP-1-inducing) effects of bortezomib significantly improves the efficacy of proteasome inhibition in breast cancer cells. Thus, future development of drugs targeting MKP-1 offer promise of combination therapies with reduced toxicity and enhanced cell death in breast cancer.

Novel triterpenoid 25-hydroxy-3-oxoolean-12-en-28-oic acid induces growth arrest and apoptosis in breast cancer cells

25-Hydroxy-3-oxoolean-12-en-28-oic acid (Amooranin-AMR) is a triterpene acid isolated from the stem bark of a tropical tree (Amoora rohituka) grown wild in India. A herbal preparation used for the treatment of cancer by the Ayurvedic system of medicine contains the stem bark of Amoora rohituka as one of the ingredients. In this paper, we show that AMR displays a strong inhibitory effect on survival of human breast carcinoma MDA-468, breast adenocarcinoma MCF-7 cells compared to breast epithelial MCF-10A control cells. A 50% decrease in cells (IC50) ranged from 1.8 to 14.6 microM and cell growth was suppressed by arresting cell cycle at G2 + M phase. AMR effectively induces apoptosis and triggered a series of effects associated with apoptosis including cleavage of caspase-8, -9, -3, Bid and ER stress in MDA-468 cells and caspase- 8, -9, -6 and Bid in MCF-7 cells, release of cytochrome c from the mitochondria, cleavage of poly (ADP-ribose) polymerase (PARP) and DNA fragmentation with a concomitant upregulation of p53, Bax and down-regulation of Bcl-2 in MDA-468 cells, but Bax unchanged in MCF-7 cells. The use of caspase blocking peptides and acridine orange staining confirmed the involvement of primarily caspase-9 and -3 in MDA-468 cells with mutated p53 and primarily caspase-8, -9 and -6 in MCF-7 cells expressing wt p53. We also observed in MCF-7/p53siRNA cells AMR treatment caused reduced expression of Bcl-2 without affecting levels of Bax similar to MCF-7 cells treated with AMR and proteolytic activation of Bax in MDA-468 cells. These results suggest that AMR induces apoptosis in human breast carcinoma cells via caspase activation pathway and likely it is a p53-independent apoptosis.