Target For Breast Cancer Therapy Research Articles

Curcumin-loaded redox-responsive mesoporous silica nanoparticles for targeted breast cancer therapy

Hypothesis: The antitumor applications of curcumin (CUR) are limited because of its low water solubility, poor stability, and low bioavailability. We developed novel nanocarrier systems for tumour targeting and controlled CUR release and evaluated their therapeutic efficacy.Experiments: The surface of mesoporous silica nanoparticles (MSN) was modified with hyaluronan (HA) or polyethyleneimine-folic acid (PEI-FA) via disulfide bonds. The capacity of the resultant nanocarriers (MSN-HA and MSN-PEI-FA, respectively) for CUR delivery was evaluated in a breast cancer cell line and a mouse xenograft model.Findings: MSN/CUR-PEI-FA and MSN/CUR-HA were cytotoxic to MDA-MB-231 breast cancer cells. Both formulations showed an enhanced cellular uptake compared with that of a non-targeted nanocarrier, with a greater cellular uptake of FA-modified nanoparticles than that of HA-modified nanoparticles. Accordingly, MSN-PEI-FA showed more precise targeting and higher accumulation in tumours than did MSN-HA, as visualized by live imaging. Both types of nanoparticles had good biocompatibility and low toxicity, and MSN/CUR-PEI-FA inhibited the tumour growth to a greater degree than did free CUR. Thus, MSN/CUR-PEI-FA are a promising drug delivery system for the treatment of breast cancer.

Reactive Oxygen Species-Biodegradable Gene Carrier for the Targeting Therapy of Breast Cancer.

An ideal gene-carrying vector is supposed to exhibit outstanding gene-condensing capability with positively charged macromolecules to protect the carried gene during in vivo circulation and a rapid dissociation upon microenvironmental stimuli at the aimed sites to release the escorted gene. Currently, it still remains a challenge to develop an ideal gene carrier with efficient transfection ability and low toxicity for clinical applications. Herein, we have innovatively introduced a reactive oxygen species (ROS)-biodegradable boric acid ester linkage in elaborating the design of a gene carrier. In virtue of the featured intracellular characteristics such as the high level of ROS in tumor cells, an ROS-biodegradable electropositive polymer derived from branched polyethylenimine (BPEI) with a low molecular weight (1.2k) through a cross-linking reaction by the boric acid ester bond was developed in this study to achieve condensation and escorting of carried genes. Furthermore, the polymer was modified with substance P (SP) peptide as the targeting ligand through polyethylene glycol. The final fabricated SP-cross-linked BPEI/plasmid DNA nanoparticles exhibit favorable biocompatibility, ROS-cleavability, and fine targeting ability as well as high transfection efficiency compared with parental BPEI1.2k both in vitro and in vivo. SP-cross-linked BPEI/small interfering RNA (pololike kinase 1) polyplex possesses favorable gene-silencing effects in vitro and satisfactory antitumor ability in vivo. Hopefully, this novel cross-linked electropositive polymer may serve well as a safe and efficient gene-delivery vehicle in the clinic.

Abstract P3-07-03: Targeting low voltage-activated calcium channels in HER2-positive breast cancer

Abstract Under physiological conditions low voltage-activated calcium channels (LVA, also called T-type channels) occur mostly in the brain, peripheral nervous system, smooth muscles, and pacemaker of the heart. However, LVA are often aberrantly expressed in various cancers and their overexpression is inversely correlated with outcomes. Active LVA contribute to proliferation, progression and resistance to therapy in several human cancers, including breast cancer (BC). The molecular mechanism of this activity is still not fully understood, and there is a lack of pre-clinical studies that target LVA in animal models of BC.Data from the Cancer Genome Atlas (TCGA) show a positive correlation between HER2 gene amplification and LVA channel overexpression, particularly of Cav3.1 (CACNA1G) subunit. The goal of this study is to identify functional links between HER2 receptor signaling and LVA channels, and validate LVA Ca2+ channels as a potential target for BC therapy. Inhibition of LVA, by small molecule antagonist mibefradil (MIB) or shRNA, significantly decreased the activity of PI3K/mTOR/AKT pathway in HER2-positive BC cell lines, blocked cell cycle progression, and at higher concentrations induced apoptotic cell death. Furthermore, LVA antagonist, mibefradil, sensitized cells to trastuzumab, lapatinib and paclitaxel, commonly used standard treatments for HER2-positive BC. To test the effects of LVA inhibition in vivo, the MMTV-PyMT mouse model of BC was used. In this model several features of HER2-positive BC are recapitulated, such as activation of PI3K/AKT/mTOR pathway, overexpression of HER2, BIRC5 and cyclin D1, and low expression of ERα, PGR and FOXA1. In PyMT animals palpable tumors can be detected at the age of 10-12 weeks, and 100% of animals will develop high tumor burden, including lung metastases, at the age of 15-20 weeks. Expression of CACNA1G subunit was detected in breast epithelial cells of 7 week old mice, and throughout the adult life, in both wild-type and PyMT animals, but CACNA1G was not expressed in lung or skeletal muscles. In in vitro experiments, cell lines derived from PyMT tumors were sensitive to MIB. In in vivo experiment, 5 to 7 weeks-old PyMT mice were fed either control or MIB-containing diet ad lib. Analysis of mouse serum revealed stable MIB concentration of ˜1500 ng/mL achieved within one week of treatment. In MIB-fed animals tumor appearance was delayed by 2 weeks, and the tumors were smaller as compared to control, thus suggesting a supporting role for LVA channels in breast tumor development and progression. Together, our observations provide new insights into the role of Ca2+ channels in HER2 driven BC and posit a future use of LVA channel antagonists for the treatment HER2-positive breast tumors. Citation Format: Dziegielewska B, Dunlap-Brown ME, Warnock WT, Dillon PM, Bouton AH, Dziegielewski J. Targeting low voltage-activated calcium channels in HER2-positive breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-07-03.

Promotional effect of microRNA-194 on breast cancer cells via targeting F-box/WD repeat-containing protein 7.

Breast cancer is the most common type of malignant cancer in females. An increasing number of studies have revealed that microRNAs (miR), which belong to a class of small non-coding RNAs, serve an important role in a number of human cancer subtypes. In the present study, the role of miR-194 in breast cancer cells and its underlying mechanisms were investigated. The results demonstrated that the serum levels of miR-194 were significantly higher in patients of the poorly differentiated and well-differentiated groups, compared with in healthy adults. Additionally, the serum level of miR-194 was significantly higher in the poorly differentiated group compared with in the well-differentiated group. In order to further investigate the role of miR-194 in breast cancer cells, the present study transfected two breast cancer cell lines, MCF-7 and MDA-MB-231, with an empty vector (control), miR-194 (overexpression), antagomiR-194 (inhibitor, functional knock down) or antagomiR-194 and miR-194. An MTT assay was performed in order to detect the proliferation of breast cancer cells in the various groups. The results revealed that the overexpression of miR-194 significantly accelerated cell proliferation, whereas the inhibition of miR-194 significantly decelerated the proliferation of MCF-7 and MDA-MB-231 cells. Furthermore, the expression levels of cyclin D and cyclin E were significantly upregulated in miR-194 overexpressing cells, and the expression levels of cyclin D and cyclin E were significantly downregulated in miR-194 inhibited cells, as compared with in control cells. No significant change was observed in the level of proliferation of cells co-transfected with miR-194 and antagomiR-194, compared with in the control cells. According to the hypothesis suggesting possible target genes of miR-194, the present study proposed that F-box/WD repeat-containing protein 7 (Fbxw-7) may be a direct target of miR-194, which was confirmed by a luciferase reporter assay. The present study suggested that miR-194 expression promoted the proliferation of breast cancer cells by targeting Fbxw-7, and may serve as a biomarker and a novel target for breast cancer therapy.

Distinct expression of CDCA3, CDCA5, and CDCA8 leads to shorter relapse free survival in breast cancer patient.

Breast cancer is a dangerous disease that results in high mortality rates for cancer patients. Many methods have been developed for the treatment and prevention of this disease. Determining the expression patterns of certain target genes in specific subtypes of breast cancer is important for developing new therapies for breast cancer. In the present study, we performed a holistic approach to screening the mRNA expression of six members of the cell division cycle-associated gene family (CDCA) with a focus on breast cancer using the Oncomine and The Cancer Cell Line Encyclopedia (CCLE) databases. Furthermore, Gene Expression-Based Outcome for Breast Cancer Online (GOBO) was also used to deeply mine the expression of each CDCA gene in clinical breast cancer tissue and breast cancer cell lines. Finally, the mRNA expression of the CDCA genes as related to breast cancer patient survival were analyzed using a Kaplan-Meier plot. CDCA3, CDCA5, and CDCA8 mRNA expression levels were significantly higher than the control sample in both clinical tumor sample and cancer cell lines. These highly expressed genes in the tumors of breast cancer patients dramatically reduced patient survival. The interaction network of CDCA3, CDCA5, and CDCA8 with their co-expressed genes also revealed that CDCA3 expression was highly correlated with cell cycle related genes such as CCNB2, CDC20, CDKN3, and CCNB1. CDCA5 expression was correlated with BUB1 and TRIP13, while CDCA8 expression was correlated with BUB1 and CCNB1. Altogether, these findings suggested CDCA3, CDCA5, and CDCA8 could have a high potency as targeted breast cancer therapies.

SMARCAD1 in Breast Cancer Progression

Background/Aims: Breast cancer is the most common cancer in women worldwide, and within this cancer type, triple-negative breast cancers have the worst prognosis. The identification of new genes associated with triple-negative breast cancer progression is crucial for developing more specific anti-cancer targeted therapies, which could lead to a better management of these patients. In this context, we have recently demonstrated that SMARCAD1, a DEAD/H box-containing helicase, is involved in breast cancer cell migration, invasion, and metastasis. The aim of this study was to investigate the impact of the stable knockdown of SMARCAD1 on human breast cancer cell progression. Methods: Using two different designs of shRNA targeting SMARCAD1, we investigated the impact of the stable knockdown of SMARCAD1 on human breast cancer cell proliferation and colony growth in vitro and on tumour growth in chick embryo and nude mouse xenograft models in vivo using MDA-MB-231 (ER^-/PR^-/ HER2^-) and T47D (ER⁺/PR^+/-/HER2^-) human breast cancer cell lines. Results: We found that SMARCAD1 knockdown resulted in a significant decrease in breast cancer cell proliferation and colony formation, leading to the significant inhibition of tumour growth in both the chick embryo and nude mouse xenograft models. This inhibition was due, at least in part, to a decrease in IKKβ expression. Conclusion: These results indicate that SMARCAD1 is involved in breast cancer progression and can be a promising target for breast cancer therapy.

An In Vitro Study of the Photodynamic Effectiveness of GO-Ag Nanocomposites against Human Breast Cancer Cells.

Graphene-based materials have garnered significant attention because of their versatile bioapplications and extraordinary properties. Graphene oxide (GO) is an extremely oxidized form of graphene accompanied by the functional groups of oxygen on its surface. GO is an outstanding platform on which to pacify silver nanoparticles (Ag NPs), which gives rise to the graphene oxide-silver nanoparticle (GO-Ag) nanocomposite. In this experimental study, the toxicity of graphene oxide-silver (GO-Ag) nanocomposites was assessed in an in vitro human breast cancer model to optimize the parameters of photodynamic therapy. GO-Ag was prepared using the hydrothermal method, and characterization was done by X-ray diffraction, field-emission scanning electron microscope (FE-SEM), transmission Electron Microscopy (TEM), energy dispersive X-rays Analysis (EDAX), atomic force microscopy and ultraviolet-visible spectroscopy. The experiments were done both with laser exposure, as well as in darkness, to examine the phototoxicity and cytotoxicity of the nanocomposites. The cytotoxicity of the GO-Ag was confirmed via a methyl-thiazole-tetrazolium (MTT) assay and intracellular reactive oxygen species production analysis. The phototoxic effect explored the dose-dependent decrease in the cell viability, as well as provoked cell death via apoptosis. An enormously significant escalation of 1O2 in the samples when exposed to daylight was perceived. Statistical analysis was performed on the experimental results to confirm the worth and clarity of the results, with p-values < 0.05 selected as significant. These outcomes suggest that GO-Ag nanocomposites could serve as potential candidates for targeted breast cancer therapy.

Cancer-specific PERK signaling drives invasion and metastasis through CREB3L1

PERK signaling is required for cancer invasion and there is interest in targeting this pathway for therapy. Unfortunately, chemical inhibitors of PERK’s kinase activity cause on-target side effects that have precluded their further development. One strategy for resolving this difficulty would be to target downstream components of the pathway that specifically mediate PERK’s pro-invasive and metastatic functions. Here we identify the transcription factor CREB3L1 as an essential mediator of PERK’s pro-metastatic functions in breast cancer. CREB3L1 acts downstream of PERK, specifically in the mesenchymal subtype of triple-negative tumors, and its inhibition by genetic or pharmacological methods suppresses cancer cell invasion and metastasis. In patients with this tumor subtype, CREB3L1 expression is predictive of distant metastasis. These findings establish CREB3L1 as a key downstream mediator of PERK-driven metastasis and a druggable target for breast cancer therapy.

Expression of PRL-3 regulates proliferation and invasion of breast cancer cells in vitro.

The protein tyrosine phosphatase PRL-3 plays an important role in cancer cell migration, invasion and metastasis. In breast cancer, PRL-3 is overexpressed in 70-75% of tumors and even more frequently in lymph node metastases. Moreover, PRL-3 overexpression in breast cancer is associated with an adverse disease outcome. Aim of this study was to determine the role of PRL-3 in breast cancer cell proliferation, migration and invasion in vitro. PRL-3 mRNA expression was evaluated in 6 breast cancer cell lines by quantitative real-time PCR. To investigate the effect of PRL-3 expression in breast cancer cells in vitro we both up- and downregulated PRL-3 expression in breast cancer cells and performed in vitro wound repair cell motility assays and invasion assays. The influence of PRL-3 knockdown in MCF-7 cells on the expression of several gene products involved in cell invasion and cytoskeletal function was evaluated with real-time PCR. PRL-3 mRNA expression was demonstrated in all breast cancer cell lines evaluated. Knockdown of PRL-3 in MCF-7 cells resulted in decreased proliferation, wound healing and invasion. PRL-3 knockdown in MCF-7 cells resulted in a significant reduction of heparanase, MMP-9, actin gamma-2 and Myosin 9 expression, and significant elevation of E-cadherin. We conclude that PRL-3 is an important regulatory factor for breast cancer cell proliferation and invasion. Loss of PRL-3 function induces an antimetastatic gene expression profile in breast cancer cells. Due to its role in tumor growth and metastasis, PRL-3 emerges as a new therapeutic target in breast cancer therapy.

Silibinin: An Inhibitor of Mir-181a Gene Expression in Sk-Br-3 Breast Cancer Cell Line

Abstract: Background: Mir-181a has been considered as an attractive molecular target for breast cancer therapy. The main objective of this work is to assess the inhibitory effects of silibinin, a herbal substance, on proliferation, apoptosis and Mir-181a gene expression in human breast cancer cell line SK-BR-3. Materials and Methods: Human breast cancer cell line SK-BR-3 was treated with various concentration of silibinin. Cell viability was assessed by MTT assay and apoptosis by flow cytometry. Expression of human mir-181a gene was measured with real-time PCR. Results: Silibinin inhibits growth of SK-BR-3 cells in a dose- and time-dependent manner and effectively induces apoptosis of SK-BR-3 cells. In addition, silibinin caused a decrease in Mir-181a level. Conclusion: These findings suggest that cell viability along with Mir-181a gene expression in breast cancer cells could be reduced by silibinin. These results suggest that silibinin inhibits the proliferation of SK-BR-3 cells, and it induces apoptosis by down-regulating Mir-181a expression in breast cancer cells. Key words: Silibinin, Cell Viability, Apoptosis, Sk-Br-3 Cell Line, Mir-181a.

MiR-221/222 promote cancer stem-like cell properties and tumor growth of breast cancer via targeting PTEN and sustained Akt/NF-κB/COX-2 activation

MicroRNAs (miRNAs) play an important role in regulating cancer stem cell (CSC). Previous studies have shown that microRNA-221/222 (miR-221/222) cluster are involved in the propagation of breast cancer stem cell (BCSC), however, the underlying molecular mechanisms are still not fully understood. In this study, we found that miR-221/222 were overexpressed in highly aggressive breast cancer MDA-MB-231 cells, that are enriched in markers for epithelial-mesenchymal transition (EMT) and BCSCs, than in MCF-7 cells. Phosphatase and tensin homolog (PTEN) was confirmed to be the target of miR-221/222 in breast cancer cells. MiR-221/222 enhanced breast cancer cell growth, migration and invasion by downregulating PTEN. Importantly, both ectopic expression of miR-221/222 and PTEN knockdown increased the mammosphere formation capacity and the expression of the stemness marker ALDH1. MiR-221/222 lentivirus vector infected MCF-7 cells produced larger subcutaneous tumors, while shRNA vector of PTEN showed similar trend. Along with the downregulation of PTEN caused by miR-221/222 in the breast cancer cells and the xenograft tumor tissues, Akt phosphorylation (p-Akt), NF-κB p65 and phosphorylated p65 (p-p65), and cyclooxygenase-2 (COX-2) were all overexpressed compared to the negative control. Taken together, our findings indicate that miR-221/222 play a critical role in the propagation of BCSCs and tumor growth possibly through targeting PTEN, which in turn activating the Akt/NF-κB/COX-2 pathway. MiR-221/222 might represent the potential target of breast cancer therapy.

Diaphanous-related formin-3 overexpression inhibits the migration and invasion of triple-negative breast cancer by inhibiting RhoA-GTP expression

Triple-negative breast cancer (TNBC) is associated with a high risk of metastasis, recurrence, and poor prognosis. TNBC is insensitive to existing endocrine and targeted breast cancer therapies because it lacks the expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Therefore, there is an urgent need for identifying novel targets to improve the efficacy of TNBC treatment. Diaphanous-related formin-3 (DIAPH3) regulates cytoskeleton formation to regulate cell adhesion, migration, and differentiation. A previous study showed that DIAPH3 promoted the metastasis of prostate cancer. However, DIAPH3 expression in TNBC and its effect on TNBC development have not been reported to date. In present study, we investigated the expression and functions of DIAPH3 in TNBC. Results of immunohistochemical staining showed that DIAPH3 expression significantly decreased in breast cancer tissues, especially TNBC tissues, compared with that in paired non-tumor tissues. In addition, DIAPH3 expression was associated with TNM stage and lymph node metastasis, but not with tumor size in patients with TNBC. Further, DIAPH3 overexpression clearly suppressed the migration and invasion of MDA-MB-231 cells and decreased the expression of Ras Homolog Family Member A (RhoA), RhoA-GTP, Matrix Metallopeptidase 2 (MMP-2), and MMP-9. Thus, we predict that DIAPH3 overexpression inhibits the migration and invasion of TNBC by inhibiting RhoA-GTP expression and the results of the present study provide new insights for developing DIAPH3-targeting therapies for TNBC.

Downregulation of ATG5-dependent macroautophagy by chaperone-mediated autophagy promotes breast cancer cell metastasis

Recent data have shown that the expression of lysosome-associated membrane protein type 2 A (LAMP2A), the key protein in the chaperone-mediated autophagy (CMA) pathway, is elevated in breast tumor tissues. However, the exact effects and mechanisms of CMA during breast cancer metastasis remain largely unknown. In this study, we found that the LAMP2A protein level was significantly elevated in human breast cancer tissues, particularly in metastatic carcinoma. The increased LAMP2A level was also positively correlated with the histologic grade of ductal breast cancer. High LAMP2A levels also predicted shorter overall survival of breast cancer patients. Downregulation of CMA activity by LAMP2A knockdown significantly inhibited the growth and metastasis of both MDA-MB-231 and MDA-MB-468 breast cancer cells in vivo and in vitro, while upregulation of CMA activity by LAMP2A overexpression had the opposite effect. Mechanistically, we found that elevated CMA activity mediated increased growth and metastasis of human breast cancer cells by downregulating the activity of autophagy-related gene 5 (ATG5)-dependent macroautophagy. Collectively, these results indicate that the anti-macroautophagic property is a key feature of CMA-mediated tumorigenesis and metastasis and may, in some contexts, serve as an attractive target for breast cancer therapies.

Overexpression of Forkhead Box L1 (FOXL1) Inhibits the Proliferation and Invasion of Breast Cancer Cells.

Forkhead box L1 (FOXL1) is a member of the Forkhead box (FOX) superfamily and was reported to be dysregulated in various types of cancers. However, its expression pattern and underlying cellular function in breast cancer remain largely unexplored. Thus, the aim of this study was to detect FOXL1 expression in breast cancer and to analyze its role in the progression of breast cancer. Our results demonstrated that FOXL1 expression at both the mRNA and protein levels was downregulated in breast cancer tissues and cell lines. Ectopic FOXL1 suppressed breast cancer cell proliferation, migration, and invasion in vitro. Furthermore, overexpression of FOXL1 significantly attenuated tumor growth in breast xenograft models in vivo. Finally, overexpression of FOXL1 significantly downregulated the protein expression levels of β-catenin, c-Myc, and cyclin D1 in MDA-MB-231 cells. Taken together, the present study demonstrated that FOXL1 inhibited the proliferation, invasion, and migration of breast cancer in vitro and breast tumor growth in vivo through deactivating the Wnt/β-catenin signaling pathway. Thus, these findings suggest that FOXL1 may be a potential novel target for breast cancer therapy.

CCCTC-binding factor inhibits breast cancer cell proliferation and metastasis via inactivation of the nuclear factor-kappaB pathway.

CCCTC-binding factor (CTCF) is an important epigenetic regulator implicated in multiple cellular processes, including growth, proliferation, differentiation, and apoptosis. Although CTCF deletion or mutation has been associated with human breast cancer, the role of CTCF in breast cancer is questionable. We investigated the biological functions of CTCF in breast cancer and the underlying mechanism. The results showed that CTCF expression in human breast cancer cells and tissues was significantly lower than that in normal breast cells and tissues. In addition, CTCF expression correlated significantly with cancer stage (P = 0.043) and pathological differentiation (P = 0.029). Furthermore, CTCF overexpression resulted in the inhibition of proliferation, migration, and invasion, while CTCF knockdown induced these processes in breast cancer cells. Transcriptome analysis and further experimental confirmation in MDA-MD-231 cells revealed that forced overexpression of CTCF might attenuate the DNA-binding ability of nuclear factor-kappaB (NF-κB) p65 subunit and inhibit activation of NF-κB and its target pro-oncogenes (tumor necrosis factor alpha-induced protein 3 [TNFAIP3]) and genes for growth-related proteins (early growth response protein 1 [EGR1] and growth arrest and DNA-damage-inducible alpha [GADD45a]). The present study provides a new insight into the tumor suppressor roles of CTCF in breast cancer development and suggests that the CTCF/NF-κB pathway is a potential target for breast cancer therapy.

FSIP1 binds HER2 directly to regulate breast cancer growth and invasiveness

Fibrous sheath interacting protein 1 (FSIP1), a spermatogenesis-related testicular antigen, is expressed in abundance in breast cancers, particularly in those overexpressing human epidermal growth factor receptor 2 (HER2); however, little is known about its role in regulating the growth and metastasis of breast cancer cells. We and others have shown previously that FSIP1 expression in breast cancer correlates positively with HER2-positivity, recurrence, and metastases and negatively with survival. Here, using coimmunoprecipitation and microscale thermophoresis, we find that FSIP1 binds to the intracellular domain of HER2 directly. We further show that shRNA-induced FSIP1 knockdown in SKBR3 and MCF-7 breast cancer cells inhibits proliferation, stimulates apoptosis, attenuates epithelial-mesenchymal transition, and impairs migration and invasiveness. Consistent with reduced proliferation and enhanced apoptosis, xenotransplantation of SKBR3 cells stably transfected with sh-FSIP1 into nu/nu mice results in reduced tumor volumes compared with sh-NC transplants. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) mapping using sh-FSIP1 gene signature yielded associations with extracellular matrix protein pathways, and a reduction in SNAI2 protein expression was confirmed on Western blot analysis. Complementarily, interrogation of the Connectivity Map using the same gene signature yielded, as top hits, chemicals known to inhibit epithelial-mesenchymal transition, including rapamycin, 17-N-allylamino-17-demethoxygeldanamycin, and LY294002. These compounds phenocopy the effects of sh-FSIP1 on SKBR3 cell viability. Thus, FSIP1 suppression limits oncogenesis and invasiveness in breast cancer cells and, considering its absence in most other tissues, including normal breast, may become a potential target for breast cancer therapy.

Abstract 4413: Targeting glutamine metabolism in MUC1 expressing triple negative breast cancer

Abstract Breast cancer, the second leading cause of cancer deaths in women, accounts for nearly 1 in 3 cancer cases diagnosed in the U.S. women. Triple negative breast cancer (TNBC) accounts for approximately 15-25% of all breast cancer cases and has an increased incidence of metastasis, high recurrence within 1-3 years and a high mortality rate. Therefore, identifying factors that facilitate tumor growth and metastasis have the potential to serve as novel molecular targets for breast cancer therapy. Mucin1 (MUC1), a glycoprotein associated with chemoresistance, is aberrantly overexpressed in TNBC and facilitates growth and metastasis of TNBC cells. Recent studies suggest a role for MUC1 in modulating cancer cell metabolism to support tumor growth. In the present study we examined the role that MUC1 plays in TNBC tumor metabolism; thus facilitating tumor growth. Our results indicate that MUC1 expression facilitates glutamine metabolism. A correlation between MUC1 expression, glutamine dependency, and amino-oxyacetate (AOA) sensitivity was established. These alterations can be attributed in part to alterations in the expression of genes regulating glutamine metabolism. Collectively, these findings suggest that MUC1 serves as a metabolic regulator in TNBC, facilitating metabolic reprogramming of glutamine that influences growth of TNBC. Additionally, the findings with AOA’s effectiveness provide evidence for potential therapeutic utility, particularly for MUC1 overexpressing TNBC. Citation Format: Gennifer D. Goode, Venugopal Gunda, Pankaj Singh. Targeting glutamine metabolism in MUC1 expressing triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4413. doi:10.1158/1538-7445.AM2017-4413

Abstract 1145: Overcoming chemoresistance and blocking metastasis in breast cancer by targeting HuR

Abstract Patients with metastatic breast cancer have a dismal 5-year survival rate of only 24%. Chemoresistance is another contributor to the high mortality of advanced breast cancer. The RNA-binding protein, Hu antigen R (HuR), is overexpressed at all stages of breast cancer development. Cytoplasmic HuR accumulation correlates with high-grade malignancy, poor distant disease-free survival and serves as a prognostic factor for poor clinical outcome in breast cancer. HuR promotes tumorigenesis by promoting mRNA stability and translation of proteins implicated in proliferation, survival, angiogenesis, invasion, and metastasis. HuR also modulates sensitivity of breast cancer cells to chemotherapy. Taken together, HuR is an emerging target for breast cancer therapy, especially metastatic breast cancer. Using shRNA and CRISPR technologies to modulate HuR expression in breast cancer cells, we found that cells with HuR KD/KO were less invasive and more sensitive to chemotherapy. In an effort to discover small molecules that disrupt the HuR-mRNA interaction and block HuR functions in breast cancer progression, metastasis and chemoresistance, high throughput screening (HTS) was carried out in several chemical libraries (~23,000 compounds) using fluorescence polarization (FP) assay, which identified several initial hits with sub-micromolar inhibitory constants (Ki). Those potential inhbitors were then validated by ALPHA assay (Amplified Luminescent Proximity Homogeneous Assay), confirmed by Surface Plasmon Resonance (SPR). In cell-based assays, top hit KH-3 and its optimized analogs, specifically shortened HuR target mRNA half-lifes and decreased the level of the encoded proteins. Moreover, those compounds inhibited invasion and restored chemosensitivity. qPCR arrays focusing on specific pathways revealed that HuR inhibitors potently upregulated metastatic suppressors and downregulated genes frequently overexpressed in lung metastases. In animal studies, KH-3 not only exhibited potent antitumor efficacy in orthotopic xenografts of breast cancer, but also efficiently blocked experimental metastasis. In conclusion, we identified potent and specific small molecule inhibitors of HuR-mRNA interaction for potential anti-metastatic therapy for breast cancer with HuR overexpression. Citation Format: Xiaoqing Wu, Rebecca Marquez, Shuang Han, Lan Lan, Dan A. Dixon, Jeffrey Aubé, Danny R. Welch, Liang Xu. Overcoming chemoresistance and blocking metastasis in breast cancer by targeting HuR [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1145. doi:10.1158/1538-7445.AM2017-1145

Abstract 5134: Novel trifunctional immunoliposome delivery system to minimize resistance and side effects for anticancer therapy

Abstract Background: Breast cancer (BC) is the second leading cause of cancer death in women worldwide. About 25% of BCs have overexpression of the HER2 receptor. Although HER2 targeted therapies have shown considerable improvement in HER2-positive BC patients’ outcome, treatment resistance remains a clinical challenge. Here, we sought to develop and evaluate a novel tri-functional immune-liposome (TFIL) that overcomes HER2 treatment resistance and associated cardiotoxicity by dually targeting HER2 on BC cells and CD3 receptors on cytotoxic T-lymphocytes (CTLs). Material and methods: Anti-HER2 (Trastuzumab) and anti-CD3 (OKT-3) antibodies, were conjugated to lipid nanoparticles by the micelle-transfer method, and the resulting formulation was purified by dextran gradient ultra-centrifugation. Targeted lipid nanoparticles were formulated with a fluorescent lipophilic dye, DiD, for studying receptor binding and internalization. Studies were conducted with HER2-positive BT474 cells and CD3-positive Jurkat cells using flow cytometry analyses. Doxorubicin (DXR) was encapsulated in the nanoparticles by the remote-loading technique for cell-kill experiments. In vitro cell-kill studies were conducted by co-culturing BT474 as the target cells, and peripheral blood mononuclear cells as the effector cells, at varying ratios. Results: Purified formulations were successfully characterized for conjugation by determining the protein to lipid ratio. Flow cytometry analyses demonstrated successful cell binding and/or internalization of the TFIL with both the HER2 and CD3-positive cell lines. Moreover, these dual-targeted nanoparticles were able to retarget T cells to kill HER2 positive BC cells, and showed improved efficacy compared to non-targeted and plain HER2-targeted formulations in vitro. Conclusion: A novel drug delivery system, TFIL, that targets HER2 receptors on tumor cells, CD3 on CTLs, and is able to slowly release DXR was successfully developed and evaluated in vitro on HER2 overexpressing BC cells. Our findings show great promise at overcoming resistance and associated cardiotoxicity to present HER2 targeted BC therapies, and may translate into improved anti-tumor activity clinically compared to other treatment options. Citation Format: Tanaya R. Vaidya, Sihem Ait-Oudhia. Novel trifunctional immunoliposome delivery system to minimize resistance and side effects for anticancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5134. doi:10.1158/1538-7445.AM2017-5134

Investigation of discriminant metabolites in tamoxifen-resistant and choline kinase-alpha-downregulated breast cancer cells using 1H-nuclear magnetic resonance spectroscopy.

Metabolites linked to changes in choline kinase-α (CK-α) expression and drug resistance, which contribute to survival and autophagy mechanisms, are attractive targets for breast cancer therapies. We previously reported that autophagy played a causative role in driving tamoxifen (TAM) resistance of breast cancer cells (BCCs) and was also promoted by CK-α knockdown, resulting in the survival of TAM-resistant BCCs. There is no comparative study yet about the metabolites resulting from BCCs with TAM-resistance and CK-α knockdown. Therefore, the aim of this study was to explore the discriminant metabolic biomarkers responsible for TAM resistance as well as CK-α expression, which might be linked with autophagy through a protective role. A total of 33 intracellular metabolites, including a range of amino acids, energy metabolism-related molecules and others from cell extracts of the parental cells (MCF-7), TAM-resistant cells (MCF-7/TAM) and CK-α knockdown cells (MCF-7/shCK-α, MCF-7/TAM/shCK-α) were analyzed by proton nuclear magnetic resonance spectroscopy (1H-NMRS). Principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) revealed the existence of differences in the intracellular metabolites to separate the 4 groups: MCF-7 cells, MCF-7/TAM cells, MCF-7-shCK-α cells, and MCF-7/TAM/shCK-α cells. The metabolites with VIP>1 contributed most to the differentiation of the cell groups, and they included fumarate, UA (unknown A), lactate, myo-inositol, glycine, phosphocholine, UE (unknown E), glutamine, formate, and AXP (AMP/ADP/ATP). Our results suggest that these altered metabolites would be promising metabolic biomarkers for a targeted therapeutic strategy in BCCs that exhibit TAM-resistance and aberrant CK-α expression, which triggers a survival and drug resistance mechanism.