SKBR3 Breast Cancer Cells Research Articles

PHD2 Targeting Overcomes Breast Cancer Cell Death upon Glucose Starvation in a PP2A/B55α-Mediated Manner

SummaryB55α is a regulatory subunit of the PP2A phosphatase. We have recently found that B55α-associated PP2A promotes partial deactivation of the HIF-prolyl-hydroxylase enzyme PHD2. Here, we show that, in turn, PHD2 triggers degradation of B55α by hydroxylating it at proline 319. In the context of glucose starvation, PHD2 reduces B55α protein levels, which correlates with MDA-MB231 and MCF7 breast cancer cell death. Under these conditions, PHD2 silencing rescues B55α degradation, overcoming apoptosis, whereas in SKBR3 breast cancer cells showing resistance to glucose starvation, B55α knockdown restores cell death and prevents neoplastic growth in vitro. Treatment of MDA-MB231-derived xenografts with the glucose competitor 2-deoxy-glucose leads to tumor regression in the presence of PHD2. Knockdown of PHD2 induces B55α accumulation and treatment resistance by preventing cell apoptosis. Overall, our data unravel B55α as a PHD2 substrate and highlight a role for PHD2-B55α in the response to nutrient deprivation.

The function and mechanism of ErbB3 and IGF1R in breast cancer with Herceptin resistance

Objective To investigate the role of epidermal growth factor receptor 3 (ErbB3) and insulin-like growth factor-1 receptor (IGF1R) in enhancing the resistance of Herceptin in human breast cancer. Methods HRG (Heregulin, the ligand of ErbB3) or IGF2 (insulin-like growth factor2, the ligand of IGF1R) was correspondingly added into breast cancer cells SKBR3 and BT474, and then 3-(4, 5-dimenthylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and were performed in these cells to evaluate the sensitivity of these cells to Herceptin. Furthermore, we used HRG or IGF2 antibodies to inhibit their joint receptors in Herceptin-resistant breast cancer cells SKBR3/POOL2 and BT474/HR20. Finally, the sensitivity of these treated cells to Herceptin was detected via MTS assay. HRG or IGF2 was added into breast cancer cell BT474, and co-IP assay was used to detect the expressions of ErbB3 and IGF1R which combined with ErbB2. Results The treatment groups used HRG or IGF2 enhanced the resistance of Herceptin in Herceptin-sensitive breast cancer cells. On the other hand, we used antibodies of HRG and IGF2 to block their combining with their receptors in Herceptin-resistant breast cancer cells, the cells became more sensitive to Herceptin. BT474 cell was treated with HRG or IGF2. The expressions of ErbB3 and IGF1R which combined with ErbB2 were increased. Conclusions The formation of heterodimers ErbB2/ErbB3 and ErbB2/IGF1R might enhance the resistance of Herceptin in ErbB2-overexpression human breast cancers. Key words: Receptor, epidermal growth factor; Receptor, IGF type 1; Breast neoplasms/DT/ME; Drug tolerance; Antibodies, monoclonal/TU

HER-2/EGFR, the major targets for anti-metastasis effect of tetraarsenic oxide on SKBR3 breast cancer cells

HER-2/EGFR, the major targets for anti-metastasis effect of tetraarsenic oxide on SKBR3 breast cancer cells

How is Herstatin, a tumor suppressor splice variant of the oncogene HER2, regulated?

ABSTRACTThe human epidermal growth factor receptor 2 (HER2)/receptor tyrosine-protein kinasebB-2 (ERBB2) is overexpressed in 20–30% of breast tumors leading to faster growing and more aggressive tumors. Alternative splicing generates a functionally distinct HER2 variant called Herstatin, which is produced by the inclusion of intron 8. Herstatin acts as a tumor suppressor by effectively blocking HER2 activity and cell proliferation, while promoting apoptosis. In the present study we investigated HER2 pre-mRNA regulatory sequences and splicing factors which regulate the alternative splicing of Herstatin. A Herstatin minigene, comprising exon 8/intron 8/exon 9 of HER2 was generated and subsequent in vitro splicing assays revealed that RNA secondary structure and somatic mutations did not impact on inclusion of intron 8. However, using RNase-assisted RNA chromatography, followed by mass spectrometry, we identified six RNA-binding proteins (splicing factors) that bind to RNA sequences surrounding exon 8/intron 8 and intron 8/exon 9 boundaries; these included hnRNP I, H1, D, A2/B1 and hnRNPA1 plus the SR protein SRSF1. Specifically, overexpression of hnRNP A1 significantly increased retention of intron 8 resulting in higher levels of Herstatin in SKBR3 breast cancer cells whereas SRSF1 only had a marginal effect in decreasing Herstatin but increased exogenous HER2 levels under these experimental conditions. In conclusion, we have identified the first splicing factors and regulatory sequences that are involved in the production of Herstatin.

ANTITUMOR EFFECT OF SUNITINIB AND BORTEZOMIB ON BREAST CANCER CELL LINE IN VITRO

The discovery for effective combinations of anticancer drugs for treatment for breast cancer is the actual problem in the experimental chemotherapy. In this paper we conducted a study of antitumor effect of the combination of sunitinib and bortezomib against MDA-MB-231 and SKBR-3 breast cancer cell lines in vitro. We found that bortezomib in non-toxic concentrations can potentiate the antitumor activity of sunitinib. MDA-MB-231 cell line has showed great sensitivity to the combination of bortezomib and sunitinib in vitro. Bortezomib and sunitinib caused reduced expression of receptor tyrosine kinases VEGFR1, VEGFR2, PDGFRa, PDGFRß and c-Kit on HER2- and HER2+ breast cancer cell lines

Uptake and Cytotoxicity Characterization of Radioiodine in MCF-7 and SKBR3 Breast Cancer Cell Lines

Radioiodine is an effective and low-risk therapy modality in well-differentiated thyroid cancer patients post near-total thyroidectomy. Extra thyroidal tumors such as breast cancer are known to be able to uptake radioiodine. The aim of this stud y was to analyze the uptake, efflux and cytotoxicity of radioiodine for two molecular types of breast cancer cell lines . Two types of breast cancer cell lines were used in this study, MCF-7 (luminal A type) and SKBR3 (HER2 type). The HaCaT cell line was used as normal cells. Iodine -125 (I-125) was used to measured radioiodine uptake and efflux. Clonogenic assay was used to assess cytotoxicity of iodine-131 (I-131) based on the tested cell reproductive ability. The radioiodine uptake in SKBR3 cell s was found to be higher than that of MCF-7 and HaCaT cells at p <0.05. The reproductive ability of MCF-7 cells are lower than SKBR3 cells at p <0.05 . Both breast cancer cells have less reproduction ability than HaCaT cells at p <0.05 . Both types of breast cancer cells present the ability to uptake radioiodine and show a high sensitivity to radioiodine exposure. N ormal cells also demonstrate an ability to uptake radioiodine. However, they have a better tolerance to the amount of I-131 exposure. These findings could potentially lead to the use if I-131 for ablative therapy in breast cancer, similiar to its use in the treatment of thyroid cancer. Received: 4 October 2015; Revised: 14 August 2016; Accepted: 2 September 2016

An ultrasensitive sandwich-type electrochemical immunosensor for the determination of SKBR-3 breast cancer cell using rGO-TPA/FeHCFnano labeled Anti-HCT as a signal tag

Here in, a high sensitive sandwich-type electrochemical immunosensor for the determination of SKBR-3 breast cancer cell has been fabricated using of green synthesized reduced graphene oxide as a platform to the immobilization of primary Herceptin antibody (Anti-HCT). The various reduced graphene oxide-tetrasodium 1, 3, 6, 8-pyrenetetrasulfonic acid/metal hexacyanoferrates (rGO-TPA/MHCFnano) nanocomposites included rGO-TPA/FeHCF, rGO-TPA/CoHCF, rGO-TPA/NiHCF and rGO-TPA/CuHCF were used as electrochemical labels of secondary Herceptine antibody. The obtained result showed that the sensitivity of proposed sandwich-type electrochemical immunosensor for the determination of SKBR-3 breast cancer cells (30,000cellsmL−1) using rGO-TPA/FeHCFnano labeled secondary Herceptine antibody was higher than the other rGO-TPA/MHCFnano-labeled secondary Herceptine antibodies. The differential pulse voltammetry (DPV) technique was used for the determination of SKBR-3 breast cancer cell in the concentration range of 500–30,000cellsmL−1 with the limit of detection of 21cellsmL−1. The proposed sandwich-type electrochemical immunosensor exhibited high selectivity, liner range responsibility and good stability.

The Enrichment of Survivin in Exosomes from Breast Cancer Cells Treated with Paclitaxel Promotes Cell Survival and Chemoresistance.

The generation and release of membrane-enclosed packets from cancer cells, called extracellular vesicles (EVs), play important roles in propagating transformed phenotypes, including promoting cell survival. EVs mediate their effects by transferring their contents, which include specific proteins and nucleic acids, to target cells. However, how the cargo and function of EVs change in response to different stimuli remains unclear. Here, we discovered that treating highly aggressive MDAMB231 breast cancer cells with paclitaxel (PTX), a chemotherapy that stabilizes microtubules, causes them to generate a specific class of EV, namely exosomes, that are highly enriched with the cell survival protein and cancer marker, Survivin. Treating MDAMB231 cells with a variety of other chemotherapeutic agents, and inhibitors that block cell growth and survival, did not have the same effect as PTX, with the exception of nocodazole, another inhibitor of microtubule dynamics. Exosomes isolated from PTX-treated MDAMB231 cells strongly promoted the survival of serum-starved and PTX-treated fibroblasts and SKBR3 breast cancer cells, an effect that was ablated when Survivin was knocked-down from these vesicles using siRNA. These findings underscore how the enrichment of a specific cargo in exosomes promotes cell survival, as well as can potentially serve as a marker of PTX resistance.

Anti-Cancer Activity of Methanol Extracts of Cichorium Intybus on Human Breast Cancer SKBR3 Cell Line

Anti-Cancer Activity of Methanol Extracts of Cichorium Intybus on Human Breast Cancer SKBR3 Cell Line

Anti-Cancer Activity of Methanol Extracts of Cichorium Intybus on Human Breast Cancer SKBR3 Cell Line

Abstract Background: Breast cancer is themost prevalent cancer and the second cause of death among women around the world. Inmany cancers, including breast cancer, Fatty acid synthase (FASN) gene expression is increased significantly. In breast cancer cell lines, expression of FASN is higher in HER2 positive cell line like SKBR3 than the others. FASN is the key enzyme for fatty acid synthesis de novo pathway and it is producing palmitate which is necessary for cellmembrane formation. Cichoriumintybus is amedicinal plant that effectively leads to inhibition of fatty acid synthase and thus reduces the percentage of survival of cancer cell lines. Objectives: The aimof this studywas to evaluate the effect ofmethanol extract of Chicoriumintybus root on percentage of survival in SKBR3 cell line. Methods: Human breast cancer SKBR3 cell line was cultured in DMEM medium. Methanol extract of Cichorium intybus root was extracted and different dilutions (200, 300, 400, 500 and 600g/mL) were added to cell culture. Cell viability was quantitated by MTT assay after 24, 48 and 72 hours. Results: Cichorium intybus could decrease cell viability. The effects of extract on cell viability were observed after 24, 48 and 72 hours on SKBR3 cell line and IC50 was 800, 400 and 300 after 24, 48 and 72 hours of treatment, respectively. Conclusions: Our study shows thatmethanol extract of Cichoriumintybus has cytotoxic effects on tumor cells. This is a pilotwork for further evaluation in the future.

Anti-proliferation of breast cancer cells with itraconazole: Hedgehog pathway inhibition induces apoptosis and autophagic cell death

Itraconazole is a common antifungal which may have promise for treating various human cancers. We report that itraconazole was cytotoxic to MCF-7 and SKBR-3 breast cancer cell lines via apoptosis by altering mitochondria membrane potential, reducing BCL-2 expression and elevating caspase-3 activity. Itraconazole also induced autophagic cell death via LC3-II expression upregulation, P62/SQSTM1 degradation, autophagosome formation and increases in autophagic puncta. Itraconazole treatment inhibited hedgehog pathway key molecular expression, such as SHH and Gli1, resulting in promotion of apoptosis and autophagy. The anti-proliferation effect of itraconazole-induced apoptosis and autophagy via hedgehog pathway inhibition was confirmed with Gli1 inhibitor GANT61 and SHH siRNA, GANT61 and SHH siRNA synergistically enhanced cytotoxicity induced by itraconazole. A human xenograft nude mouse model corroborated the anti-breast cancer activity as evidenced by reduced tumor size, and increased tumor tissue apoptosis and autophagy. Thus, itraconazole has a potent anti-breast cancer activity that may be improved when combined with hedgehog pathway inhibitors.

Targeting the entry region of Hsp90's ATP binding pocket with a novel 6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl amide

The molecular chaperone Hsp90 plays an important role in cancer cell survival and proliferation by regulating the maturation and stabilization of numerous oncogenic proteins. Due to its potential to simultaneously disable multiple signaling pathways, Hsp90 has emerged as an attractive therapeutic target for cancer treatment. In this study, the design, synthesis, and biological evaluation of a series of Hsp90 inhibitors are described. Among the synthetic compounds, 6,7-dihydrothieno [3,2-c]pyridin-5(4H)-yl amide 19 exhibits a remarkable binding affinity to the N-terminus of Hsp90 in a fluorescence polarization (FP) binding assay (IC50 = 50.3 nM). Furthermore, it effectively inhibits the proliferation of H1975 non-small cell lung cancer (NSCLC) and Skbr3 breast cancer cell lines with GI50 values of 0.31 μM and 0.11 μM, respectively. Compound 19 induces the degradation of the Hsp90 client proteins including EGFR, Her2, Met, c-Raf, and Akt, and consequently promotes apoptotic cancer cell death. Compound 19 also inhibits the growth of H1975 xenografts in NOD-scid IL2R gammanull mice without any apparent body-weight loss. The immunohistologic evaluation indicates that compound 19 decreases the expression of Akt in xenograft tumor tissue via an inhibition of the Hsp90 chaperon function. Additionally, the cytochrome P450 assay indicates that compound 19 has no effect on the activities of five major P450 isoforms (IC50 > 50 μM for 1A2, 2C9, 2C19, 2D6, and 3A), suggesting that clinical interactions between compound 19 and the substrate drugs of the five major P450 isoforms are not expected. Overall, compound 19 represents a new class of Hsp90 inhibitor with its 6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl-amide structure, and it has the therapeutic potential to overcome drug resistance in cancer chemotherapy.

Static micro-array isolation, dynamic time series classification, capture and enumeration of spiked breast cancer cells in blood: the nanotube–CTC chip

We demonstrate the rapid and label-free capture of breast cancer cells spiked in blood using nanotube-antibody micro-arrays. 76-element single wall carbon nanotube arrays were manufactured using photo-lithography, metal deposition, and etching techniques. Anti-epithelial cell adhesion molecule (anti-EpCAM), Anti-human epithelial growth factor receptor 2 (anti-Her2) and non-specific IgG antibodies were functionalized to the surface of the nanotube devices using 1-pyrene-butanoic acid succinimidyl ester. Following device functionalization, blood spiked with SKBR3, MCF7 and MCF10A cells (100/1000 cells per 5 μl per device, 170 elements totaling 0.85 ml of whole blood) were adsorbed on to the nanotube device arrays. Electrical signatures were recorded from each device to screen the samples for differences in interaction (specific or non-specific) between samples and devices. A zone classification scheme enabled the classification of all 170 elements in a single map. A kernel-based statistical classifier for the ‘liquid biopsy’ was developed to create a predictive model based on dynamic time warping series to classify device electrical signals that corresponded to plain blood (control) or SKBR3 spiked blood (case) on anti-Her2 functionalized devices with ∼90% sensitivity, and 90% specificity in capture of 1000 SKBR3 breast cancer cells in blood using anti-Her2 functionalized devices. Screened devices that gave positive electrical signatures were confirmed using optical/confocal microscopy to hold spiked cancer cells. Confocal microscopic analysis of devices that were classified to hold spiked blood based on their electrical signatures confirmed the presence of cancer cells through staining for DAPI (nuclei), cytokeratin (cancer cells) and CD45 (hematologic cells) with single cell sensitivity. We report 55%–100% cancer cell capture yield depending on the active device area for blood adsorption with mean of 62% (∼12 500 captured off 20 000 spiked cells in 0.1 ml blood) in this first nanotube–CTC chip study.

Combined SRC inhibitor saracatinib and anti-ErbB2 antibody H2-18 produces a synergistic antitumor effect on trastuzumab-resistant breast cancer

Despite of the effectiveness of the anti-ErbB2 humanized antibody trastuzumab, trastuzumab resistance emerges as a major and common clinical problem. Thus, circumventing trastuzumab resistance has become an urgent need. Recently, Src inhibitor saracatinib has drawn great attention for its key role in trastuzumab response. As shown in our previous study, H2-18, an anti-ErbB2 antibody, could potently induce programmed cell death (PCD) in trastuzumab-resistant breast cancer cells. Here we combined H2-18 and a Src inhibitor, saracatinib, and studied the antitumor activity of this drug combination in trastuzumab-resistant breast cancer cell lines. The results showed that H2-18 and saracatinib could synergistically inhibit cell proliferation of BT-474, SKBR-3, HCC-1954 and HCC-1419 breast cancer cell lines in vitro. H2-18 plus saracatinib could also inhibit the HCC-1954 tumor growth more effectively in vivo than each drug alone. H2-18 plus saracatinib showed a significantly more potent PCD-inducing activity compared with either H2-18 or saracatinib alone. We conclude that enhanced PCD may contribute to the superior antitumor efficacy of this combination therapy. The combination of H2-18 and SRC inhibitor has the potential to be translated into clinic.

Mycophenolic acid potentiates HER2-overexpressing SKBR3 breast cancer cell line to induce apoptosis: involvement of AKT/FOXO1 and JAK2/STAT3 pathways.

Trastuzumab has been successfully used as a first-line therapy specific for HER2-overexressing breast cancer patients. However, despite the effectiveness of trastuzumab, the occurrence of inherent and acquired resistance remains as the main challenge of the therapy. Thus, this has motivated efforts toward finding new therapeutic strategies including combining trastuzumab with other drugs to enhance its therapeutic efficacy. In that line, we investigated the capability of mycophenolic acid (MPA), an inhibitor of de novo guanine nucleotide synthesis with potential anti-cancer activity, on improving the response to trastuzumab among SKBR3 cells as well as trastuzumab resistant SKBR3-TR cells. Our data indicated that irrespective to trastuzumab sensitivity of cells, MPA effectively inhibited cell growth through inducing adipocyte-like cell differentiation as well as blocking cell cycle progression at G1 phase along with augmentation of p27kip expression level. Furthermore, combined treatment with trastuzumab and MPA was more potent in cell growth inhibition, cell cycle arrest and apoptosis induction, as evident by flow cytometric analyses and caspase-3 production, in both trastuzumab sensitive and resistant SKBR3 cells. Besides, western blot analysis showed that elevated apoptosis induction in both cell groups was associated with attenuation in phosphorylation of some key elements of HER2 signaling pathway including AKT, ERK, STAT3 and consequently augmentation in FOXO1 expression level in response to combination of trastuzumab and MPA. These data suggest that manipulation of intracellular GTP level by MPA and consequent molecular perturbation in some of the cell survival and pro-apoptotic relevant signaling pathways might provide an alternative clinical strategy for chemosensitization of resistant breast cancer cells to anti- HER2 therapy.

Prunella vulgaris Polysaccharide Inhibits Growth and Migration of Breast Carcinoma-Associated Fibroblasts by Suppressing Expression of Basic Fibroblast Growth Factor.

To study the effects of Prunella vulgaris polysaccharide (PVP) on human breast carcinoma-associated fibroblasts (CAFs). Cell viability was detected by 3-[4,5-dimethylthiazol-2-yl]-2,5-(3-carboxymethoxyphenyl)-2-4-sulfophenyl)-2H-tetrazolium (MTS) assay. Wound healing experiment and transwell migration assay were used to investigate the anti-migration effects. Flow cytometry was applied to detect cell apoptosis and cell cycle distribution. Reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay were used to detect the expression of basic fibroblast growth factor (bFGF) in CAFs. Culture SKBr-3 with CAFs conditioned medium (CAFs-CM) to evaluate the indirect function on the proliferation of breast cancer SKBr-3 cells. PVP inhibited the viability of CAFs by inducing apoptosis (P <0.01) and arresting cell cycle (P <0.01). It also inhibited the migration of CAFs (P <0.01). bFGF promoted CAFs proliferation (P <0.01) and migration (P <0.01), protected CAFs from apoptosis (P <0.05) and reduced G0 phase to 49.06% (P <0.01). However, these effects of bFGF on CAFs could be abrogated by PVP. Culturing SKBr-3 with CAFs-CM, PVP could inhibit the viability of breast cancer SKBr-3 cells indirectly. Moreover, PVP reduced the mRNA expression (P <0.01) and protein secretion of bFGF (P <0.01) in CAFs. PVP could exert an anti-cancer effect on breast CAFs by inhibiting bFGF expression, thus inhibiting the growth of breast cancer SKBr-3 cells indirectly.

Effect of low doses of estradiol and tamoxifen on breast cancer cell karyotypes.

Evidence supports a role of 17&-estradiol (E2) in carcinogenesis and the large majority of breast carcinomas are dependent on estrogen. The anti-estrogen tamoxifen (TAM) is widely used for both treatment and prevention of breast cancer; however, it is also carcinogenic in human uterus and rat liver, highlighting the profound complexity of its actions. The nature of E2- or TAM-induced chromosomal damage has been explored using relatively high concentrations of these agents, and only some numerical aberrations and chromosomal breaks have been analyzed. This study aimed to determine the effects of low doses of E2 and TAM (10&8 mol L&1 and 10&6 mol L&1 respectively) on karyotypes of MCF7, T47D, BT474, and SKBR3 breast cancer cells by comparing the results of conventional karyotyping and multi-FISH painting with cell proliferation. Estrogen receptor (ER)-positive (+) cells showed an increase in cell proliferation after E2 treatment (MCF7, T47D, and BT474) and a decrease after TAM treatment (MCF7 and T47D), whereas in ER& cells (SKBR3), no alterations in cell proliferation were observed, except for a small increase at 96 h. Karyotypes of both ER+ and ER& breast cancer cells increased in complexity after treatments with E2 and TAM leading to specific chromosomal abnormalities, some of which were consistent throughout the treatment duration. This genotoxic effect was higher in HER2+ cells. The ER&/HER2+ SKBR3 cells were found to be sensitive to TAM, exhibiting an increase in chromosomal aberrations. These in vitro results provide insights into the potential role of low doses of E2 and TAM in inducing chromosomal rearrangements in breast cancer cells.

Palmitate-induced ER stress increases trastuzumab sensitivity in HER2/neu-positive breast cancer cells

BackgroundHER2/neu-positive breast cancer cells have recently been shown to use a unique Warburg-like metabolism for survival and aggressive behavior. These cells exhibit increased fatty acid synthesis and storage compared to normal breast cells or other tumor cells. Disruption of this synthetic process results in apoptosis. Since the addition of physiological doses of exogenous palmitate induces cell death in HER2/neu-positive breast cancer cells, the pathway is likely operating at its limits in these cells. We have studied the response of HER2/neu-positive breast cancer cells to physiological concentrations of exogenous palmitate to identify lipotoxicity-associated consequences of this physiology. Since epidemiological data show that a diet rich in saturated fatty acids is negatively associated with the development of HER2/neu-positive cancer, this cellular physiology may be relevant to the etiology and treatment of the disease. We sought to identify signaling pathways that are regulated by physiological concentrations of exogenous palmitate specifically in HER2/neu-positive breast cancer cells and gain insights into the molecular mechanism and its relevance to disease prevention and treatment.MethodsTranscriptional profiling was performed to assess programs that are regulated in HER2-normal MCF7 and HER2/neu-positive SKBR3 breast cancer cells in response to exogenous palmitate. Computational analyses were used to define and predict functional relationships and identify networks that are differentially regulated in the two cell lines. These predictions were tested using reporter assays, fluorescence-based high content microscopy, flow cytometry and immunoblotting. Physiological effects were confirmed in HER2/neu-positive BT474 and HCC1569 breast cancer cell lines.ResultsExogenous palmitate induces functionally distinct transcriptional programs in HER2/neu-positive breast cancer cells. In the lipogenic HER2/neu-positive SKBR3 cell line, palmitate induces a G2 phase cell cycle delay and CHOP-dependent apoptosis as well as a partial activation of the ER stress response network via XBP1 and ATF6. This response appears to be a general feature of HER2/neu-positive breast cancer cells but not cells that overexpress only HER2/neu. Exogenous palmitate reduces HER2 and HER3 protein levels without changes in phosphorylation and sensitizes HER2/neu-positive breast cancer cells to treatment with the HER2-targeted therapy trastuzumab.ConclusionsSeveral studies have shown that HER2, FASN and fatty acid synthesis are functionally linked. Exogenous palmitate exerts its toxic effects in part through inducing ER stress, reducing HER2 expression and thereby sensitizing cells to trastuzumab. These data provide further evidence that HER2 signaling and fatty acid metabolism are highly integrated processes that may be important for disease development and progression.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2611-8) contains supplementary material, which is available to authorized users.

Abstract LB-080: Imprime PGG, a β-glucan PAMP (pathogen-associated molecular pattern) activates the direct killing functions of innate immune cells in concert with tumor targeting antibodies

Abstract Imprime PGG (Imprime) is a soluble yeast 1,3/1,6 β-glucan PAMP (pathogen-associated molecular pattern). As a PAMP, Imprime triggers innate immune function, activating the direct killing functions of innate immune cells, facilitating MDSC differentiation and macrophage repolarization as well as enabling dendritic cell maturation and antigen presentation, driving T cell expansion and activation. In the clinic, Imprime is administered intravenously and is well-tolerated. In multiple clinical trials (&amp;gt; 400 subjects), including randomized phase 2 studies in NSCLC, Imprime has consistently shown promising increases in both objective tumor response and patient survival. To date, the clinical experience with Imprime has centered on combinations with tumor targeting monoclonal antibodies (Mabs). For instance, Imprime combined with rituximab and alemtuzumab in CLL patients yielded a 65% complete response rate (vs 37% historical CR rate for alemtuzumab plus rituximab). We sought to better characterize the effect of Imprime in concert with tumor-targeting mAbs. We show that Imprime enhances the effector functions of multiple innate immune cell lineages. We first evaluated the generation of Reactive Oxygen Species (ROS) in neutrophils isolated from human healthy volunteer whole blood. These neutrophils, but not those from vehicle treated whole blood, specifically recognized B cell lymphomas (Raji) only after opsonization with anti-CD20 Mabs (rituximab, ofatumumab, obinatuzumab), generating a substantial ROS burst that coincided with enhanced tumor cell cytotoxicity. Similarly, increased antibody dependent cellular phagocytosis (ADCP) mediated by monocyte-derived macrophages was evident against antibody-opsonized lymphomas (Z138 B cell lymphomas with obinutuzumab) and solid tumor cells (SKBr3 breast cancer cells with trastuzumab) from Imprime-treated whole blood. Likewise, increased Natural Killer (NK) cell-mediated antibody dependent cellular cytotoxicity (ADCC) was evident only after Imprime treatment against antibody-opsonized cancer cells (SKBR3 with trastuzumab, K562 erythroleukemia cells with anti-glycophorin-A). In vivo, we now show that Imprime administered intravenously significantly enhances the anti-tumor efficacy of trastuzumab in a patient derived xenograft model of breast cancer, reducing mean tumor volume to ∼ 50% of that achieved by trastuzumab alone. In the B16 lung experimental metastasis model, the addition of Imprime to the anti-TRP1 tumor targeting antibody TA-99 significantly reduces both the number and size of B16 lung metastases. Together, these data show that Imprime stimulates the innate immune system, augmenting the anti-tumor efficacy of a diverse array of tumor targeting antibodies in multiple tumor types. Citation Format: Steven M. Leonardo, Ross B. Fulton, Keith B. Gorden, Katy Fraser, Ben Harrison, Takashi Kangas, Adria Jonas, Yumi Yokoyama, Nadine Ottoson, Nandita Bose, Jeremy R. Graff. Imprime PGG, a β-glucan PAMP (pathogen-associated molecular pattern) activates the direct killing functions of innate immune cells in concert with tumor targeting antibodies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-080.

Abstract 2179: Macrolide toxin Mycalolide B is a potent inhibitor of HER2 cancer cell invasion and is the basis of actin targeted therapy for metastatic cancers

Abstract Breast and ovarian cancers are among the leading causes of cancer related deaths in women worldwide. Human epidermal growth factor receptor 2 (HER2) is highly expressed in a subset of these cancers that show high rates of progression to metastatic disease. Metastasis is driven by filamentous actin (F-actin) based protrusions that penetrate and degrade extracellular matrix (ECM) to facilitate tumor invasion. In this study, we tested an actin-depolymerizing macrolide toxin Mycalolide B, as a potential suppressor of highly metastatic HER2+ breast and ovarian cancer cell models. Dose responses with Mycalolide B in SKBR3 breast cancer and SKOV3 ovarian cancer cells resulted in similar cytotoxicity (∼65 nM IC50) profiles. In addition, Mycalolide B doses well below the IC50 showed potent suppression of leading edge protrusions, and motility in SKBR3 and SKOV3 cancer cells. This also correlated with reduced ECM degradation and Transwell invasion at low nanomolar doses of Mycalolide B. In contrast, other F-actin based processes such as endocytosis of HER2 and EGFR, were less sensitive to Mycalolide B treatment. However, Mycalolide B treatment did skew the size of endocytic vesicles, which may reflect defects in F-actin based vesicle motility or maturation. Given that HER2 cancers have been effectively targeted by Trastuzumab and Trastuzumab-based antibody-drug conjugates, we are currently testing the compatibility of combined treatments with Mycalolide B and Trastuzumab, for their effects on F-actin based invasion of HER2+ cancers. This strategy may yield a novel class of antibody-drug conjugate, and lead to new HER2 targeted therapies that suppress tumor metastasis by disrupting early steps that are dependent on efficient F-actin polymerization. Citation Format: Rodette N. Williams, Andrew W. Craig, John S. Allingham. Macrolide toxin Mycalolide B is a potent inhibitor of HER2 cancer cell invasion and is the basis of actin targeted therapy for metastatic cancers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2179.