miR-186 Regulates the Initiation and Development of Breast Cancer via SHP-1 Methylation

Abstract Background Change in the methylation status of genomic DNA, especially in CpG islands in the promoter region, is considered to be an early event in tumor initiation, leading to silencing of gene expression, subsequent abnormalities in gene structure and function, and malignant transformation of the cell. Due to the abnormal expression of miR-186 and SHP-1 in breast cancer tissues and cells, we propose that miR-186 is closely related to the methylation of SHP-1Method Using 5-azacytidine as a de-methylation agent and Validating with Setylation-specific polymerase chain reaction (MSP) after treatment. Measurement of the viability of breast cancer cells using the CCK-8 method Measurement of the apoptotic rate of breast cancer cells using annexin V-FITC/PI double labeling. Cell metastasis were measured by wound healing assay. Luciferase reporter assays was used to confirm the target of MiR-186. SHP-1 and miR-186 expression was measured by RT-PCR and western blot.Results In the present study, we found that SHP-1 expression was reduced to various degrees in all 5 cell lines (UACC-812, MDA-MB-213, MDA-MB-468, SK-RB-3 and MCF-7). 5-azacytidine can remove the methylation from the SHP-1 promoter region. Apoptosis was observed in MCF-7 cells after demethylation of the SHP-1 gene promoter region by 5-azacytidine, and the effect was time- and concentration-dependent. Luciferase reporter assays showed that miR-186 promotes methylation through binding with the 3’ UTR of the SHP-1 promoter region.Western blot showed miR-186 regulates the initiation and development of tumor cells through the SHP-1-JAK-STAT axis. In animal models, low expression of miR-186 can cause significantly limited tumor growth.Conclusion The low SHP-1 expression may be an important factor in the initiation of breast cancer, and that miR-186 could serve as an excellent molecular diagnostic marker and a possible therapeutic target.

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MiR-105-3p acts as an oncogene to promote the proliferation and metastasis of breast cancer cells by targeting GOLIM4

BMC Cancer ◽

10.1186/s12885-021-07909-2 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Bo Lin ◽

Chunhua Liu ◽

Enyi Shi ◽

Qiu Jin ◽

Wenhui Zhao ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Molecular Mechanisms ◽

Quantitative Polymerase Chain Reaction ◽

Luciferase Reporter ◽

Reporter Assays ◽

Proliferation And Metastasis ◽

Cancer Tissues ◽

Mcf 7

Abstract Background Dysregulated miRNAs are involved in carcinogenesis of the breast and may be used as prognostic biomarkers and therapeutic targets during the cancer process. The purpose of this study was to explore the effect of miR-105-3p on the tumourigenicity of breast cancer and its underlying molecular mechanisms. Methods Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to detect the expression of miR-105-3p in breast cancer tissues and cell lines. The impacts of miR-105-3p on the proliferation, migration, invasion and apoptosis of human breast cancer cells (MCF-7 and ZR-75-30) were evaluated by CCK-8 assays, Transwell chamber assays, TUNEL assays and western blot analyses. In addition, bioinformatics and luciferase reporter assays were used to determine the target genes of miR-105-3p. Results The expression of miR-105-3p was elevated in breast cancer tissues and increased with tumour severity. Downregulation of miR-105-3p could inhibit cell proliferation, suppress cell migration/invasion, and promote cell apoptosis in MCF-7 and ZR-75-30 cells. Furthermore, Golgi integral membrane protein 4 (GOLIM4) was identified as the direct target gene of miR-105-3p by bioinformatics and luciferase reporter assays. In addition, silencing GOLIM4 restored the anti-breast cancer effects induced by miR-105-3p downregulation. Conclusions MiR-105-3p acts as an oncogene to promote the proliferation and metastasis of breast cancer cells by targeting GOLIM4, which provides a new target for the prevention and treatment of breast cancer.

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MiR-218-5p promotes breast cancer progression via LRIG1

10.21203/rs.3.rs-203193/v1 ◽

2021 ◽

Author(s):

Mingping Qian ◽

Hui Xu ◽

Hongming Song ◽

Hao Xi ◽

Lin Fang

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cancer Cells ◽

Human Breast Cancer ◽

Breast Cancer Cells ◽

Luciferase Reporter ◽

Human Breast ◽

Egfr Expression ◽

Breast Tissues ◽

Mcf 7

Abstract Background : MiR-218-5p is a small non-coding RNA acting as either oncogenes or tumor suppressor genes in human cancer. The expression levels of some miRNAs in human breast cancer plays a potential role in disease pathogenesis. Methods : Thirty pairs of invasive ductal carcinoma and adjacent specimens were included in the study. Breast tissues cell lines MCF-7 and MDA-MB-231 were identified as a breast cancer research cell line. MiR-218-5p mimics, miR-218-5p inhibitor, or negative controls were transfected. Specific antibodies were probed with LRIG1, ErbB2, and EGFR. Proliferation, migration, cell cycle and apoptosis, dual-luciferase reporter assay and immunohistochemistry were used to analyze miR-218-5p、LRIG1 and so on. Results : It was shown that miR-218-5p expression was higher in 30 breast cancer specimens than adjacent normal breast tissues. In human breast cancer cells MCF-7 and MDA-MB-231, restoring miR-218-5p promoted cell proliferation and migration and inhibited cell apoptosis and cell cycle arrest in the G1 stage. Luciferase assays indicated miR-218-5p could bind with its putative target site in the 3'-untranslated region (3'-UTR) of LRIG1. RT-qPCR, western blot, and immunocytochemistry analyses all indicated miR-218-5p overexpression results in LRIG1 downregulation at the mRNA and protein levels. ErbB2 and EGFR were found to be downstream effectors of miR-218-5p. Conclusion : MiR-218-5p promotes ErbB2 and EGFR expression by inhibiting LRIG1 in breast cancer cells, which suggests miR-218-5p and LRIG1 may act as an oncogene in breast cancer and it could be used as a therapeutic target for breast cancer treatments. Keywords: Breast cancer; miR-218-5p; LRIG1; Oncogene

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hsa-miR-33-5p as a Therapeutic Target Promotes Apoptosis of Breast Cancer Cells via Selenoprotein T

Frontiers in Medicine ◽

10.3389/fmed.2021.651473 ◽

2021 ◽

Vol 8 ◽

Author(s):

Wei Zhuang ◽

Jianhui Liu ◽

Wenjin Li

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Therapeutic Target ◽

Cell Apoptosis ◽

Breast Cancer Cells ◽

Luciferase Reporter ◽

Reporter Assay ◽

Selenoprotein T ◽

Cancer Tissues ◽

Mcf 7

Objective: Increasing evidence suggests that microRNA (miRNA) participates in regulating tumor cell apoptosis. We aimed to observe the effect of hsa-miR-33-5p on the apoptosis of breast cancer cells and to explore its regulatory relationship with selenoprotein T (SelT).Methods: RT-qPCR was used to examine the expression of hsa-miR-33-5p and SelT both in breast cancer tissues and cells. MCF-7 and MDA-MB-231 cells were transfected with hsa-miR-33-5p mimics or si-SelT. Then, a flow cytometry assay was carried out to examine the apoptosis of cells. Furthermore, SelT and apoptosis-related proteins including caspase-3, caspase-8, caspase-9, Bax, and Bcl-2 were detected via RT-qPCR and western blot. A luciferase reporter assay was utilized for assessing whether SelT was targeted by hsa-miR-33-5p.Results: Downregulated hsa-miR-33-5p was found both in breast cancer tissues and cells. After its overexpression, MCF-7 cell apoptosis was significantly promoted. Furthermore, our data showed that miR-33-5p elevated apoptosis-related protein expression in MCF-7 cells. Contrary to hsa-miR-33-5p, SelT was upregulated both in breast cancer tissues and cells. SelT expression was significantly inhibited by hsa-miR-33-5p overexpression. The luciferase reporter assay confirmed that SelT was a direct target of hsa-miR-33-5p. SelT overexpression could ameliorate the increase in apoptosis induced by hsa-miR-33-5p mimics.Conclusion: Our findings revealed that hsa-miR-33-5p, as a potential therapeutic target, could accelerate breast cancer cell apoptosis.

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HOX Transcript Antisense RNA HOTAIR Abrogates Vasculogenic Mimicry by Targeting the AngiomiR-204/FAK Axis in Triple Negative Breast Cancer Cells

Non-Coding RNA ◽

10.3390/ncrna6020019 ◽

2020 ◽

Vol 6 (2) ◽

pp. 19

Author(s):

Allan Lozano-Romero ◽

Horacio Astudillo-de la Vega ◽

María Cruz del Rocío Terrones-Gurrola ◽

Laurence A. Marchat ◽

Daniel Hernández-Sotelo ◽

...

Keyword(s):

Breast Cancer ◽

Cell Migration ◽

Cancer Cells ◽

Triple Negative Breast Cancer ◽

Breast Cancer Cells ◽

Triple Negative ◽

Vasculogenic Mimicry ◽

Bioinformatic Analysis ◽

Luciferase Reporter ◽

Reporter Assays

HOX transcript antisense RNA (HOTAIR) is an oncogenic long non-coding RNA frequently overexpressed in cancer. HOTAIR can enhance the malignant behavior of tumors by sponging microRNAs with tumor suppressor functions. Vasculogenic mimicry is a hypoxia-activated process in which tumor cells form three-dimensional (3D) channel-like networks, resembling endothelial blood vessels, to obtain nutrients. However, the role of HOTAIR in vasculogenic mimicry and the underlying mechanisms are unknown in human cancers. In the current study, we investigated the relevance of HOTAIR in hypoxia-induced vasculogenic mimicry in metastatic MDA-MB-231 and invasive Hs-578t triple negative breast cancer cells. Analysis of The Cancer Genome Atlas (TCGA) database using cBioPortal confirmed that HOTAIR was upregulated in clinical breast tumors relative to normal mammary tissues. Our quantitative RT-PCR assays showed a significant increase in HOTAIR levels after 48 h hypoxia relative to normoxia in breast cancer cell lines. Remarkably, knockdown of HOTAIR significantly abolished the hypoxia-induced vasculogenic mimicry which was accompanied by a reduction in the number of 3D channel-like networks and branch points. Likewise, HOTAIR silencing leads to reduced cell migration abilities of cancer cells. Bioinformatic analysis predicted that HOTAIR has a potential binding site for tumor suppressor miR-204. Luciferase reporter assays confirmed that HOTAIR is a competitive endogenous sponge of miR-204. Congruently, forced inhibition of HOTAIR in cells resulted in augmented miR-204 levels in breast cancer cells. Further bioinformatic analysis suggested that miR-204 can bind to the 3′ untranslated region of focal adhesion kinase 1 (FAK) transcript involved in cell migration. Western blot and luciferase reporter assays confirmed that FAK is a novel target of miR-204. Finally, silencing of HOTAIR resulted in low levels of cytoplasmic FAK protein and alterations in the organization of cellular cytoskeleton and focal adhesions. In summary, our results showed, for the first time, that HOTAIR mitigates cell migration and vasculogenic mimicry by targeting the miR-204/FAK axis in triple negative breast cancer cells.

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Oncogenic p95HER2 regulates Na+–HCO3− cotransporter NBCn1 mRNA stability in breast cancer cells via 3′UTR-dependent processes*

Biochemical Journal ◽

10.1042/bcj20160054 ◽

2016 ◽

Vol 473 (21) ◽

pp. 4027-4044 ◽

Cited By ~ 10

Author(s):

Andrej Gorbatenko ◽

Christina W. Olesen ◽

Nathalie Loebl ◽

Haraldur H. Sigurdsson ◽

Carolina Bianchi ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Rna Binding ◽

Growth Factor Receptor ◽

Luciferase Reporter ◽

Central Position ◽

Reporter Expression ◽

General Role ◽

Mcf 7

The Na+–HCO3– cotransporter NBCn1 (SLC4A7) is up-regulated in breast cancer, important for tumor growth, and a single nucleotide polymorphism (SNP), rs4973768, in its 3′ untranslated region (3′UTR) correlates with increased breast cancer risk. We previously demonstrated that NBCn1 expression and promoter activity are strongly increased in breast cancer cells expressing a constitutively active oncogenic human epidermal growth factor receptor 2 (HER2) (p95HER2). Here, we address the roles of p95HER2 in regulating NBCn1 expression via post-transcriptional mechanisms. p95HER2 expression in MCF-7 cells reduced the rate of NBCn1 mRNA degradation. The NBCn1 3′UTR down-regulated luciferase reporter expression in control cells, and this was reversed by p95HER2, suggesting that p95HER2 counteracts 3′UTR-mediated suppression of NBCn1 expression. Truncation analyses identified three NBCn1 3′UTR regions of regulatory importance. Mutation of putative miRNA-binding sites (miR-374a/b, miR-200b/c, miR-29a/b/c, miR-488) in these regions did not have significant impact on 3′UTR activity. The NBCn1 3′UTR interacted directly with the RNA-binding protein human antigen R (HuR), and HuR knockdown reduced NBCn1 expression. Conversely, ablation of a distal AU-rich element increased 3′UTR-driven reporter activity, suggesting complex regulatory roles of these sites. The cancer-associated SNP variant decreased reporter expression in T-47D breast cancer cells, yet not in MCF-7, MDA-MB-231 and SK-BR-3 cells, arguing against a general role in regulating NBCn1 expression. Finally, p95HER2 expression increased total and plasma membrane NBCn1 protein levels and decreased the rate of NBCn1 protein degradation. Collectively, this is the first work to demonstrate 3′UTR-mediated NBCn1 regulation, shows that p95HER2 regulates NBCn1 expression at multiple levels, and substantiates the central position of p95HER2–NBCn1 signaling in breast cancer.

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Effects of miR-107 on the Chemo-drug sensitivity of breast cancer cells

Open Medicine ◽

10.1515/med-2019-0009 ◽

2019 ◽

Vol 14 (1) ◽

pp. 59-65 ◽

Cited By ~ 3

Author(s):

Yong Luo ◽

Tebo Hua ◽

Xia You ◽

Jinfeng Lou ◽

Xuxiong Yang ◽

...

Keyword(s):

Breast Cancer ◽

Flow Cytometry ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Target Gene ◽

Drug Sensitivity ◽

Luciferase Reporter ◽

Pcr Analysis ◽

Qrt Pcr ◽

Mcf 7

AbstractBackgroundA growing body of evidence indicates that aberrant expression of miR-107 plays a core role in cancers. This study aims to demonstrate the function of miR-107 and its roles in chemo-drug resistance in breast cancer cells.MethodologyCCK-8 assays were carried out to test the effect of miR-107 mimics on the proliferation of MCF-7 cells. The apoptosis level of each group was detected by flow cytometry. miR-107 level, mRNA levels of Bcl-2/Bax and TRIAP1 were detected by quantitative real-time Polymerase Chain Reaction (qRT-PCR) analysis. Protein levels of Bcl-2/Bax, p-Akt/Akt in MCF-7 cells were detected by using Western Blot. Lastly, the dual luciferase reporter gene assay system was used to confirm interaction between miR-107 and its target gene TRIAP1.ResultsCCK-8 assays indicated that miR-107 mimics augmented Taxol-induced cell viability inhibition. Flow cytometry showed that miR-107 mimics augmented Taxol-induced elevation of cell apoptosis. qRT-PCR analysis revealed that miR-107 mimics inhibited the mRNA expression of Bcl-2 and induced the mRNA level of Bax. Western Blotting indicated that miR-107 mimics inhibited the expression of proteins Bcl-2 and p-Akt, and induced the expression of Bax, while showing no significant effects on Akt. The relative luciferase activity revealed that oncogene TRIAP1 is a potential target gene of miR-107.ConclusionsmiR-107 plays a role in regulating chemo-drug sensitivity in mammary cancer cell by targeting TRIAP1.

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miR-17-5p Combined with Epirubicin Inhibits the Progression of Breast Cancer Cells

10.21203/rs.3.rs-127804/v1 ◽

2020 ◽

Author(s):

Lingling Zhao ◽

Zhongjian Zhu ◽

Jiang Du ◽

Yuanyu Zhao ◽

Dandan Fan

Keyword(s):

Breast Cancer ◽

Western Blot ◽

Cancer Cells ◽

Mtt Assay ◽

Breast Cancer Cells ◽

Luciferase Reporter ◽

Rt Pcr ◽

Expression Levels ◽

Cancer Tissues ◽

Mcf 7

Abstract Background: Breast cancer is the most common malignant tumor for women, which has been ranked first in women’ s cancer-related death. The objectives of the study are to uncover the underlying mechanisms of combination therapy of epirubicin with miR-17-5p in breast cancer. Methods: The expression levels of miR-17-5p were determined by quantitative RT-PCR. The survival rate of MCF-7 cell was detected respectively by MTT assay. The expression levels of miR-17-5p in MCF-7 cell was tested respectively with Ep via quantitative RT-PCR. miR-17-5p was to be transected with miR-17-5p mimic and negative control of miR-17-5p mimic (NC). Quantitative RT-PCR, MTT assay, flow cytometry assay, western blot for the proliferation and apoptosis related proteins were performed to determine the function of miR-17-5p in breast cancer cells. The bioinformatic programs TargetScan was used to predict the targets for miR-17-5p. Luciferase reporter gene assay system was used to validate and determine the targets of miR-17-5p. The relation between targets protein levels in breast cancer cells was investigated by western blot. Results: The expression levels of miR-17-5p was associated with the breast cancer tissues. The levels of miR-17-5p was down-regulated in breast cancer tissues and cells. Ep could inhibit viability of cancer cells in a concentration dependent manner and promote the expression of miR-17-5p in breast cancer cell lines. Over-expression of miR-17-5p induced cell apoptosis and upregulated the expression of p53, p21 and p27. miR-17-5p co-cultured with Ep is better than the other groups. The relative luciferase activity revealed that STAT3 was a potential target gene of miR-17-5p. Conclusions: Our work will prove that epirubicin regulated the expression of miR-17-5p to strengthen this effect of epirubicin and inhibited the progression of breast cancer.

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Hsa_circ_0029693 (circ-LATS2) promotes cell proliferation and regulates WNT5A via miR-4686 in breast cancer cells.

10.21203/rs.3.rs-26099/v1 ◽

2020 ◽

Author(s):

Jiashu Hu ◽

Kaiyao Hua ◽

Changle Ji ◽

Xuehui Wang ◽

Hongming Song ◽

...

Keyword(s):

Breast Cancer ◽

Cell Proliferation ◽

Western Blot ◽

Cancer Cells ◽

Immunohistochemical Staining ◽

Breast Cancer Cells ◽

Hippo Pathway ◽

Luciferase Reporter ◽

Ki 67 ◽

Reporter Assays

Abstract Background: Breast cancer (BC) is the most malignant form of tumor in women, which threatens females’ health. Circular RNAs (circRNAs), a class of non-coding RNAs, can act as a disease biomarker and endogenous “sponge” molecules for microRNAs (miRNAs). circRNAs may also influence the expression of their parent gene. LATS2 is a vital suppressor gene in Hippo pathway, which is a signaling cascade composed of a group of conserved kinases. The Hippo pathway plays an important role in almost all cancer types. Methods: Colony formation assays, MTT assays, wound healing assays, xenografts mice experiment, qRT-PCR, western blot assays, immunohistochemical staining assays, dual-luciferase reporter assays and Fluorescence in situ hybridization. Student’s t-test was used to analyse the results.Results: We discovered that circular RNA hsa_circ_0029693 (circ-LATS2), an exonic circRNA, are highly expressed in breast cancer cells. Furthermore, in BC patients’ samples, higher expression of circ-LATS2 was significantly related to higher percentage of Ki-67 expression; however the expression of circ-LATS2 was higher in HER2 negative BC patients compared to HER2 positive ones. We investigated the potential function and mechanism of circ-LATS2 action in BC. The results suggested that circ-LATS2 promoted cell proliferation, growth and migration. Through western blot and immunohistochemical staining assays, we found that circ-LATS2 could influence LATS2 expression. We also discovered that there was an inverse expression relationship between miR-4686 and circ-LATS2, suggesting that circ-LATS2 might act as an endogenous “sponge” for miR-4686. Using dual-luciferase reporter assays, we confirmed that circ-LATS2 can bind miR-4686. Increased miR-4686 expression caused a reduction in the protein levels of WNT5A, which is a putative target of miR-4686. We confirm this using dual-luciferase reporter assays that revealed that miR-4686 targets WNT5A by binding its 3’-untranslated region (3’UTR). Conclusions: Our results showed that circ-LATS2 expression in BC patients’ samples were significantly related to Ki-67 expression. In addition, circ-LATS2 acted as a promoter of proliferation and growth of breast cancer cells. These indicated that circ-LATS2 is a proliferative factor, similar to Ki-67; it also acts as a co-biomarker with Ki-67 in clinical treatment.

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Regulatory roles of lncRNA PANDAR in breast cancer cell proliferation

Asian Biomedicine ◽

10.2478/abm-2021-0035 ◽

2021 ◽

Vol 15 (6) ◽

pp. 285-291

Author(s):

Qinnuan Sun ◽

Xiumei Wang

Keyword(s):

Breast Cancer ◽

Cell Proliferation ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Marker Gene ◽

Cell Counting ◽

Luciferase Reporter ◽

Cell Marker ◽

Mesenchymal Transition ◽

Mcf 7

Abstract Background Breast cancer represents the second most deadly malignancy in women, and long noncoding RNAs (lncRNAs) have crucial functions in its development. Objective To investigate effects of the promoter of CDKN1A antisense DNA damage-activated RNA (PANDAR) on epithelial-mesenchymal transition (EMT) in breast cancer cells and their proliferation. Methods lncRNAs potentially regulating the transcriptional activity of the E-cadherin (E-cad, an epithelial cell marker) gene promoter were screened using a dual-luciferase reporter assay. PANDAR was overexpressed in Michigan cancer foundation 7 (MCF-7) breast cancer cells. E-cad and N-cadherin (N-cad, a mesenchymal cell marker) levels were detected by immunoblotting. Cell viability was assessed using a cell counting kit-8. Results PANDAR and TCONS00068220/LOC105375819 conservatively regulated the promoter activity of E-cad. PANDAR overexpression in MCF-7 inhibited E-cad expression, but upregulated N-cad. The enhanced expression of PANDAR promoted cell proliferation. Conclusion PANDAR is a key transcriptional repressor of E-cad and has regulatory effects on the promotion of cell proliferation. PANDAR is an oncogene in breast cancer, potentially facilitating the EMT process and promoting cell proliferation.

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Collaboration of AR and ERα in conferring resistance to an aromatase inhibitor.

Journal of Clinical Oncology ◽

10.1200/jco.2013.31.15_suppl.579 ◽

2013 ◽

Vol 31 (15_suppl) ◽

pp. 579-579

Author(s):

Yassine Rechoum ◽

Domenico Iacopetta ◽

Ines Barone ◽

Daniela Rovito ◽

Sebastiano Ando' ◽

...

Keyword(s):

Breast Cancer ◽

Aromatase Inhibitor ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Transcriptional Activity ◽

Single Agent ◽

Luciferase Reporter ◽

Breast Cancers ◽

Estrogen Synthesis ◽

Mcf 7

579 Background: We have previously shown a role for AR overexpression in tamoxifen resistance in ERα-positive MCF-7 breast cancer cells; here we hypothesized that AR overexpression might similarly be involved in resistance to the aromatase inhibitor anastrazole (Anas). Methods: MCF-7 cells were transfected to express the aromatase gene (MCF-7 Arom), or the aromatase and AR (MCF-7 AR Arom cells). Western blot analysis was used to evaluate protein levels, MTT and soft agar assays to evaluate proliferation, luciferase reporter assays to evaluate transcriptional activities and confocal microscopy was used for localization. Results: Anas inhibited androstendione (AD)-stimulated growth in MCF-7 Arom cells but not in MCF-7 AR Arom cells. Similarly, Anas did not inhibit ERα transcriptional activity in MCF-7 AR Arom cells. Enhanced activation of pIGF-1R, pIRS-1, pAKT, and pMAPK were also observed in AR Arom cells, suggesting constitutive activation of nongenomic signaling in these cells. Consistent with activation of these potential treatment “escape” mechanisms, inhibitors of AKT and IGF-1R restored sensitivity to Anas. Sensitivity to Anas was also restored using the AR antagonist MDV3100, however use of Abiraterone acetate as a single agent most effectively blocked proliferation of AR-overexpressing cells. These results suggest that both AR and ERα must be blocked to restore sensitivity to hormonal therapies in AR overexpressing ERα-positive breast cancers. Unexpectedly, AR contributed to ERα transcriptional activity in MCF-7 AR Arom cells, as shown by inhibition with the AR antagonist bicalutamide. AR and ERα co-localized both in the cytoplasm and in the nucleus of AD+Anas-treated cells, suggesting potential activation of both non-genomic and nuclear-mediated effects when AR is overexpressed in ERα-positive cells. We confirmed these findings in breast cancer cells with acquired resistance to tamoxifen. Conclusions: These results show the necessity to block both AR and ER in patients whose tumors express elevated levels of AR. In addition, inhibitors to the AKT/IGF-1R signaling pathways or direct inhibition of androgen/estrogen synthesis provide alternative approaches to restore hormone sensitivity in resistant breast tumors.

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