scholarly journals miR-449a Suppresses Tamoxifen Resistance in Human Breast Cancer Cells by Targeting ADAM22

2018 ◽  
Vol 50 (1) ◽  
pp. 136-149 ◽  
Author(s):  
Jun Li ◽  
Mingjie Lu ◽  
Jiao Jin ◽  
Xiyi Lu ◽  
Tongpeng Xu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Luciferase Assay ◽  
Protein Protein Interaction ◽  
Er Positive ◽  
Tamoxifen Resistant ◽  
Mcf 7 ◽  
Positive Breast Cancer

Background/Aims: Most of estrogen receptor positive breast cancer patients respond well initially to endocrine therapies, but often develop resistance during treatment with selective estrogen receptor modulators (SERMs) such as tamoxifen. Altered expression and functions of microRNAs (miRNAs) have been reportedly associated with tamoxifen resistance. Thus, it is necessary to further elucidate the function and mechanism of miRNAs in tamoxifen resistance. Methods: Tamoxifen sensitivity was validated by using Cell Counting Kit-8 in tamoxifen-sensitive breast cancer cells (MCF-7, T47D) and tamoxifen-resistant cells (MCF-7/TAM, T47D/ TAM). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expression level of miR-449a in tamoxifen-sensitive/-resistant cells and patient serums. Dual-luciferase assay was used to identify the binding of miR-449a and predicted gene ADAM22. The expression level of ADAM22 was determined by qRT-PCR and western blotting in miR-449a +/- breast cancer cells. Subsequently, rescue experiments were carried out to identify the function of ADAM22 in miR-449a-reduced tamoxifen resistance. Finally, Gene ontology (GO) and Protein-protein interaction analyses were performed to evaluate the potential mechanisms of ADAM22 in regulating tamoxifen resistance. Results: MiR-449a levels were downregulated significantly in tamoxifen-resistant breast cancer cells when compared with their parental cells, as well as in clinical breast cancer serum samples. Overexpression of miR-449a re-sensitized the tamoxifen-resistant breast cancer cells, while inhibition of miR-449a conferred tamoxifen resistance in parental cells. Luciferase assay identified ADAM22 as a direct target gene of miR-449a. Additionally, silencing of ADAM22 could reverse tamoxifen resistance induced by miR-449a inhibition in ER-positive breast cancer cells. GO analysis results showed ADAM22 was mainly enriched in the biological processes of cell adhesion, cell differentiation, gliogenesis and so on. Protein-protein interaction analyses appeared that ADAM22 might regulate tamoxifen resistance through PPARG, LGI1, KRAS and LYN. Conclusion: Decreased miR-449a causes the upregulation of ADAM22, which induces tamoxifen resistance of breast cancer cells. These results suggest that miR-449a, functioning by targeting ADAM22, contributes to the mechanisms underlying breast cancer endocrine resistance, which may provide a potential therapeutic strategy in ER-positive breast cancers.

scholarly journals miR-200 affects tamoxifen resistance in breast cancer cells through regulation of MYB

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yu Gao ◽  
Wenzhi Zhang ◽  
Chengwen Liu ◽  
Guanghua Li
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Breast Cancer Patients ◽  
Over Expression ◽  
Er Positive ◽  
Emt Markers ◽  
Mcf 7 ◽  
Positive Breast Cancer

AbstractResistance to tamoxifen is a major clinical challenge. Research in recent years has identified epigenetic changes as mediated by dysregulated miRNAs that can possibly play a role in resistance to tamoxifen in breast cancer patients expressing estrogen receptor (ER). We report here elevated levels of EMT markers (vimentin and ZEB1/2) and reduced levels of EMT-regulating miR-200 (miR-200b and miR-200c) in ER-positive breast cancer cells, MCF-7, that were resistant to tamoxifen, in contrast with the naïve parental MCF-7 cells that were sensitive to tamoxifen. Further, we established regulation of c-MYB by miR-200 in our experimental model. C-MYB was up-regulated in tamoxifen resistant cells and its silencing significantly decreased resistance to tamoxifen and the EMT markers. Forced over-expression of miR-200b/c reduced c-MYB whereas reduced expression of miR-200b/c resulted in increased c-MYB We further confirmed the results in other ER-positive breast cancer cells T47D cells where forced over-expression of c-MYB resulted in induction of EMT and significantly increased resistance to tamoxifen. Thus, we identify a novel mechanism of tamoxifen resistance in breast tumor microenvironment that involves miR-200-MYB signaling.

scholarly journals Narciclasine Targets STAT3 via Distinct Mechanisms in Tamoxifen-Resistant Breast Cancer Cells

2021 ◽  
Author(s):  
Chao Lv ◽  
Yun Huang ◽  
Rui Huang ◽  
Qun Wang ◽  
Hongwei Zhang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Sh2 Domain ◽  
Breast Cancers ◽  
Stat3 Phosphorylation ◽  
Er Positive ◽  
Tamoxifen Resistant ◽  
Mcf 7 ◽  
Positive Breast Cancer

Abstract Background: Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in multiple malignant tumors. Compared with regular estrogen receptor (ER)-positive breast cancers, the patients with tamoxifen-resistant breast cancers often exhibit higher level of STAT3 phosphorylation. Narciclasine (Nar) possesses strong inhibiting effects against a variety of cancer cells, however, the underlying antitumor target(s)/mechanism(s) remains barely understood. Methods: Targets prediction of narciclasine was performed by combining connectivity map (CMAP) and drug affinity responsive target stability (DARTS) strategy. Molecular and biochemical methods were used to elucidate the distinct mechanisms of narciclasine targeting STAT3. The narciclasine nano-delivery system was synthesized by thin film hydration method. Xenograft models were established to determine antitumor activity of narciclasine and its liposome in vivo.Results: In this study, we successfully identified the STAT3 was the direct target of Nar through the combination strategies of CMAP and DARTS. In ER-positive breast cancer cells, Nar could suppress phosphorylation, activation, dimerization, and nuclear translocation of STAT3 by directly binding with the STAT3 SH2 domain. Additionally, Nar could also specifically promote total STAT3 degradation via proteasome pathway and reduce the STAT3 protein stability in tamoxifen-resistant breast cancer cells (MCF-7/TR). This distinct mechanism of Nar targeting STAT3 was mainly attributed to the various levels of reactive oxygen species (ROS) in regular and tamoxifen-resistant ER-positive breast cancer cells. Meanwhile, Nar loaded nanoparticles could markedly decrease the protein levels of STAT3 in tumor sites, resulting in significant MCF-7/TR xenograft tumor regression without obvious toxicity. Conclusions: Our findings successfully highlight the STAT3 as the direct therapeutic target of Nar in ER-positive breast cancer cells, especially Nar leaded STAT3 degradation as a promising strategy for the tamoxifen-resistant breast cancer treatment.

MLL3 Induced by Luteolin Causes Apoptosis in Tamoxifen-Resistant Breast Cancer Cells through H3K4 Monomethylation and Suppression of the PI3K/AKT/mTOR Pathway

2020 ◽  
Vol 48 (05) ◽  
pp. 1221-1241 ◽  
Author(s):  
Han-Tsang Wu ◽  
Yi-En Liu ◽  
Kai-Wen Hsu ◽  
Yu-Fen Wang ◽  
Ya-Chi Chan ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Mtor Inhibitors ◽  
Ras Gene ◽  
Ras Genes ◽  
Er Positive ◽  
Tamoxifen Resistant ◽  
Positive Breast Cancer

Tamoxifen is one of the most common hormone therapy drug for estrogen receptor (ER)-positive breast cancer. Tumor cells with drug resistance often cause recurrence and metastasis in cancer patients. Luteolin is a natural compound found from various types of vegetables and exhibit anticancer activity in different cancers. This study demonstrated that luteolin inhibits the proliferation and induces apoptosis of tamoxifen-resistant ER-positive breast cancer cells. Luteolin also causes cell cycle arrest at the G2/M phase and decreases mitochondrial membrane potential. Besides, luteolin reduces the levels of activated PI3K/AKT/mTOR signaling pathway. The combination treatment of luteolin and PI3K, AKT, or mTOR inhibitors synergistically increases apoptosis in tamoxifen-resistant ER-positive breast cancer cells. Ras gene family (K-Ras, H-Ras, and N-Ras), an activator of PI3K, was transcriptionally repressed by luteolin via induction of tumor suppressor mixed-lineage leukemia 3 (MLL3) expression. MLL3 increases the level of monomethylation of Histone 3 Lysine 4 on the enhancer and promoter region of Ras genes, thus causes repression of Ras expressions. Our finding implies that luteolin was a promising natural agent against tamoxifen resistance of breast cancer.

scholarly journals SGK3 Is an Estrogen-Inducible Kinase Promoting Estrogen-Mediated Survival of Breast Cancer Cells

2011 ◽  
Vol 25 (1) ◽  
pp. 72-82 ◽  
Author(s):  
Yuanzhong Wang ◽  
Dujin Zhou ◽  
Sheryl Phung ◽  
Selma Masri ◽  
David Smith ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Protein Kinase ◽  
Cell Survival ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Dependent Manner ◽  
Binding Regions ◽  
Er Positive ◽  
Mcf 7 ◽  
Positive Breast Cancer

Serum- and glucocorticoid-inducible kinase 3 (SGK3) is a protein kinase of the AGC family of protein kinase A, protein kinase G, and protein kinase C and functions downstream of phosphatidylinositol 3-kinase (PI3K). Recent study revealed that SGK3 plays a pivotal role in Akt/protein kinase B independent signaling downstream of oncogenic PI3KCA mutations in breast cancer. Here we report that SGK3 is an estrogen receptor (ER) transcriptional target and promotes estrogen-mediated cell survival of ER-positive breast cancer cells. Through a meta-analysis on 22 microarray studies of breast cancer in the Oncomine database, we found that the expression of SGK3 is significantly higher (5.7-fold, P < 0.001) in ER-positive tumors than in ER-negative tumors. In ER-positive breast cancer cells, SGK3 expression was found to be induced by 17β-estradiol (E2) in a dose- and time-dependent manner, and the induction of SGK3 mRNA by E2 is independent of newly synthesized proteins. We identified two ERα-binding regions at the sgk3 locus through chromatin immunoprecipitation with massively parallel DNA sequencing. Promoter analysis revealed that ERα stimulates the activity of sgk3 promoters by interaction with these two ERα-binding regions on E2 treatment. Loss-of-function analysis indicated that SGK3 is required for E2-mediated cell survival of MCF-7 breast carcinoma cells. Moreover, overexpression of SGK3 could partially protect MCF-7 cells against apoptosis caused by antiestrogen ICI 182,780. Together, our study defines the molecular mechanism of regulation of SGK3 by estrogen/ER and provides a new link between the PI3K pathway and ER signaling as well as a new estrogen-mediated cell survival mechanism mediated by SGK3 in breast cancer cells.

Identification of estrogenically synthesized LRP16 as an ERα coactivator and its role in ERα-positive breast cancer

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 10676-10676
Author(s):  
W. Han ◽  
Y. Zhao ◽  
Z. Wu ◽  
Y. Mu ◽  
L. Yu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Northern Blot ◽  
Breast Cancer Cells ◽  
Tumor Diameter ◽  
Er Positive ◽  
Mcf 7 ◽  
Positive Breast Cancer

10676 Background: Aberrant ERα activity is linked to genesis and malignant progression of breast cancer through direct target gene activation or repression. A complex network of coregulatory proteins is largely believed to determine the transcriptional activity of ERα. LRP16 was identified previously to be an estrogen (E2) responsive gene, but its function involving in conferring estrogen signalling pathway is not clear. Methods: Endogenous LRP16 expression in MCF-7 cells was stably suppressed by retrovirus-mediated small interference RNA (siRNA). The effects of LRP16 expression on E2-stimulated growth and invasive ability of MCF-7 cells were determined in vitro and in vivo assays. The effects of LRP16 expression on ERα transactivation were determined by luciferase assays. The interaction of LRP16 and ERα was examined by GST pull-down and coimmunopricipitation (CoIP) assays. Northern blot and Western blot were used to detect the mRNA and protein levels of ER target genes in LRP16-inhibited MCF-7 cells. The LRP16 expression levels in primary breast cancer were detected by Northern blot. Results: Fristly, LRP16 expression was characterized to be dependent on estrogen activities. Then, LRP16 was identified to be an estrogen-independent ERα cofactor in ER-positive breast cancer cells and demonstrate that LRP16 is an essential coactivator to ERα-mediated transactivation in an estrogen-dependent manner. Suppression of LRP16 expression in ER-positive breast cancer cells specifically inhibits the transcription of ER upregulated genes, results in the increase of E-cadherin expression through ER mediation. In vitro and in vivo data demonstrate that suppression of LRP16 inhibits the ability of estrogen-stimulated proliferation and invasiveness of ER-positive breast cancer cells. The pathological and clinical characteristics of human breast cancer includining ER/PR-positiveness, tumor diameter and the involvement of axillary lymphoid nodes were tightly linked with the LRP16 gene expression level. Conclusions: These results establish a mechanistic link between estrogen receptor status, its coactivator LRP16, and progression of ER-positive breast cancers, and may provide a novel antiestrogenic target for the therapy of ER positive breast cancer. No significant financial relationships to disclose.

scholarly journals Inhibition of STAT3 enhances sensitivity to tamoxifen in tamoxifen-resistant breast cancer cells

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Seo Yun Moon ◽  
Heejin Lee ◽  
Seoree Kim ◽  
Ji Hyung Hong ◽  
Sang Hoon Chun ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Protein Expression ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Signalling Pathway ◽  
Expression Levels ◽  
Er Positive ◽  
Tamoxifen Resistant ◽  
Stat3 Signalling ◽  
Mcf 7

Abstract Background The mechanisms of endocrine resistance are complex, and deregulation of several oncogenic signalling pathways has been proposed. We aimed to investigate the role of the EGFR and Src-mediated STAT3 signalling pathway in tamoxifen-resistant breast cancer cells. Methods The ER-positive luminal breast cancer cell lines, MCF-7 and T47D, were used. We have established an MCF-7-derived tamoxifen-resistant cell line (TamR) by long-term culture of MCF-7 cells with 4-hydroxytamoxifen. Cell viability was determined using an MTT assay, and protein expression levels were determined using western blot. Cell cycle and annexin V staining were analysed using flow cytometry. Results TamR cells showed decreased expression of estrogen receptor and increased expression of EGFR. TamR cells showed an acceleration of the G1 to S phase transition. The protein expression levels of phosphorylated Src, EGFR (Y845), and STAT3 was increased in TamR cells, while phosphorylated Akt was decreased. The expression of p-STAT3 was enhanced according to exposure time of tamoxifen in T47D cells, suggesting that activation of STAT3 can cause tamoxifen resistance in ER-positive breast cancer cells. Both dasatinib (Src inhibitor) and stattic (STAT3 inhibitor) inhibited cell proliferation and induced apoptosis in TamR cells. However, stattic showed a much stronger effect than dasatinib. Knockdown of STAT3 expression by siRNA had no effect on sensitivity to tamoxifen in MCF-7 cells, while that enhanced sensitivity to tamoxifen in TamR cells. There was not a significant synergistic effect of dasatinib and stattic on cell survival. TamR cells have low nuclear p21(Cip1) expression compared to MCF-7 cells and inhibition of STAT3 increased the expression of nuclear p21(Cip1) in TamR cells. Conclusions The EGFR and Src-mediated STAT3 signalling pathway is activated in TamR cells, and inhibition of STAT3 may be a potential target in tamoxifen-resistant breast cancer. An increase in nuclear p21(Cip1) may be a key step in STAT3 inhibitor-induced cell death in TamR cells.

scholarly journals HDAC5-mediated deacetylation and nuclear localisation of SOX9 is critical for tamoxifen resistance in breast cancer

2019 ◽  
Vol 121 (12) ◽  
pp. 1039-1049 ◽  
Author(s):  
Yue Xue ◽  
Wenwen Lian ◽  
Jiaqi Zhi ◽  
Wenjuan Yang ◽  
Qianjin Li ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Transcription Factor ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Nuclear Translocation ◽  
Tamoxifen Resistance ◽  
Nuclear Localisation ◽  
Tamoxifen Resistant ◽  
Factor C ◽  
Positive Breast Cancer

Abstract Background Tamoxifen resistance remains a significant clinical challenge for the therapy of ER-positive breast cancer. It has been reported that the upregulation of transcription factor SOX9 in ER+ recurrent cancer is sufficient for tamoxifen resistance. However, the mechanisms underlying the regulation of SOX9 remain largely unknown. Methods The acetylation level of SOX9 was detected by immunoprecipitation and western blotting. The expressions of HDACs and SIRTs were evaluated by qRT-PCR. Cell growth was measured by performing MTT assay. ALDH-positive breast cancer stem cells were evaluated by flow cytometry. Interaction between HDAC5 and SOX9 was determined by immunoprecipitation assay. Results Deacetylation is required for SOX9 nuclear translocation in tamoxifen-resistant breast cancer cells. Furthermore, HDAC5 is the key deacetylase responsible for SOX9 deacetylation and subsequent nuclear translocation. In addition, the transcription factor C-MYC directly promotes the expression of HDAC5 in tamoxifen resistant breast cancer cells. For clinical relevance, high SOX9 and HDAC5 expression are associated with lower survival rates in breast cancer patients treated with tamoxifen. Conclusions This study reveals that HDAC5 regulated by C-MYC is essential for SOX9 deacetylation and nuclear localisation, which is critical for tamoxifen resistance. These results indicate a potential therapy strategy for ER+ breast cancer by targeting C-MYC/HDAC5/SOX9 axis.

scholarly journals Functional role of miR-10b in tamoxifen resistance of ER-positive breast cancer cells through down-regulation of HDAC4

BMC Cancer ◽  
2015 ◽  
Vol 15 (1) ◽  
Author(s):  
Aamir Ahmad ◽  
Kevin R. Ginnebaugh ◽  
Shuping Yin ◽  
Aliccia Bollig-Fischer ◽  
Kaladhar B. Reddy ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Functional Role ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Down Regulation ◽  
Er Positive ◽  
Positive Breast Cancer

Exosomal miR-221/222 enhances tamoxifen resistance in recipient ER-positive breast cancer cells

2014 ◽  
Vol 147 (2) ◽  
pp. 423-431 ◽  
Author(s):  
Yifang Wei ◽  
Xiaofeng Lai ◽  
Shentong Yu ◽  
Suning Chen ◽  
Yongzheng Ma ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Er Positive ◽  
Positive Breast Cancer
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