Retraction: Long non-coding RNA PVT1 facilitates cell proliferation by epigenetically regulating FOXF1 in breast cancer.

[This retracts the article DOI: 10.1039/C7RA12042G.].

Circular RNA circ_IRAK3 contributes to tumor growth through upregulating KIF2A via adsorbing miR-603 in breast cancer.

BACKGROUND: Breast cancer (BC) threatens the health of women around the world. Researchers have proved that hsa_circ_0005505 (circ_IRAK3) facilitates BC cell invasion and migration, but the regulatory mechanisms of circ_IRAK3 in BC remain mostly unknown. We aim to explore a new mechanism by which circ_IRAK3 promotes BC progression. METHODS: Levels of circ_IRAK3, microRNA (miR)-603, and kinesin family member 2A (KIF2A) mRNA in BC tissues and cells were examined by quantitative real-time polymerase chain reaction (qRT-PCR). The cell cycle progression, colony formation, and proliferation of BC cells were evaluated by flow cytometry, plate clone, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assays. The migration, invasion, and apoptosis of BC cells were determined by transwell or flow cytometry assays. Several protein levels were detected using western blotting. The targeting relationship between circ_IRAK3 or KIF2A and miR-603 was verified via dual-luciferase reporter assay. The role of circ_IRAK3 in vivo was verified by xenograft assay. RESULTS: We observed higher levels of circ_IRAK3 in BC tissues and cell lines than their respective controls. Functional experiments presented that circ_IRAK3 silencing induced BC cell apoptosis, curbed cell proliferation, migration, and invasion in vitro, and decreased tumor growth in vivo. Mechanistically, circ_IRAK3 could modulate kinesin family member 2A (KIF2A) expression through acting as a microRNA (miR)-603 sponge. miR-603 silencing impaired the effects of circ_IRAK3 inhibition on the malignant behaviors of BC cells. Also, the repressive effects of miR-603 mimic on the malignant behaviors of BC cells were weakened by KIF2A overexpression. CONCLUSIONS: circ_IRAK3 exerted a promoting effect on BC progression by modulating the miR-603/KIF2A axis, providing a piece of novel evidence for circ_IRAK3 as a therapeutic target for BC.

Application of Contrast-Enhanced 3-Dimensional T2-Weighted Volume Isotropic Turbo Spin Echo Acquisition Sequence in the Diagnosis of Prolactin-Secreting Pituitary Microadenomas.

OBJECTIVE: This study aimed to investigate the value of contrast-enhanced 3-dimensional (3D) T2-weighted (T2W) Volume Isotropic Turbo Spin Echo Acquisition (VISTA) sequence in prolactin-secreting pituitary adenoma diagnosis. METHODS: We enrolled 158 patients with hyperprolactinemia. Coronal dynamic contrast-enhanced (DCE) T1 spin echo and T2W VISTA sequences were performed. The detection of pituitary microadenomas in 3 imaging groups (DCE magnetic resonance imaging [MRI], VISTA, and DCE MRI + VISTA) were compared using McNemar test and χ2 test. RESULTS: The DCE MRI + VISTA group detected 28 more pituitary microlesions than DCE MRI alone. Among these, 20 lesions were clearly observed on VISTA images but were negative on DCE MRI. The combined sequences showed higher sensitivity (85.3%) and diagnostic accuracy (89.2%) for adenoma detection than any of the sequences alone (P < 0.01). We noted that in 65.7% of the patients with adenoma (46 of 70), a "hypointense rim" was present around the lesion on the VISTA images. Of them, 11 patients underwent surgery. Histopathology confirmed that the "hypointense rim" was a pseudocapsular structure at the edge of the adenoma. CONCLUSIONS: For patients with hyperprolactinemia, the 3D T2W VISTA sequence is an important supplement to DCE MRI, because it could improve the detection rate of pituitary microadenomas.

Transcription Factor FOSL1 Enhances Drug Resistance of Breast Cancer through DUSP7-Mediated Dephosphorylation of PEA15.

Breast cancer is one of the commonest malignancies in women with first occurrence and fifth mortality in the world. However, drug resistance has always been a major obstacle to cancer treatment. Transcription factors have been reported to have close association with drug resistance of tumors. Recently, by analyzing the data from Gene Expression Omnibus database (GSE76540), we found that transcription factor FOS like 1, AP-1 transcription factor subunit (FOSL1) was significantly upregulated in the transcriptome of doxorubicin-resistant breast cancer cells compared with that in sensitive parental cells. Therefore, we aim to explore the regulatory mechanism of FOSL1 in affecting the drug resistance of breast cancer cells. FOSL1 expression in doxorubicin-resistant breast cancer cells was firstly examined through qRT-PCR, and then its influence on the drug resistance of breast cancer cells was explored through a series of in vitro and in vivo mechanism assays. Results showed that FOSL1 promoted the drug resistance of breast cancer cells to doxorubicin both in intro and in vivo. It positively regulated the transcription of dual specificity phosphatase 7 (DUSP7) in breast cancer doxorubicin-resistant cells and DUSP7 also enhanced the drug resistance of breast cancer cells. Furthermore, FOSL1 promoted the dephosphorylation of proliferation and apoptosis adaptor protein 15 (PEA15) through DUSP7. In conclusion, it was verified that FOSL1 promoted the drug resistance in breast cancer through DUSP7-mediated dephosphorylation of PEA15. IMPLICATIONS: These initial findings suggest that the FOSL1/DUSP7/PEA15 pathway may provide a theoretical guidance for breast cancer treatment.

Aberrant super-enhancer-driven oncogene ENC1 promotes the radio-resistance of breast carcinoma.

Poor response of tumors to radiotherapy is a major clinical obstacle. Because of the dynamic characteristics of the epigenome, identification of possible epigenetic modifiers may be beneficial to confer radio-sensitivity. This research was set to examine the modulation of ectodermal-neural cortex 1 (ENC1) in radio-resistance in breast carcinoma (BC). In silico identification and immunohistochemical staining revealed that overexpression of ENC1 promoted BC metastasis to the bone and brain. Moreover, its overexpression promoted the translocation of YAP1/TAZ into the nucleus and enhanced expression of GLI1, CTGF, and FGF1 through the Hippo pathway. ENC1 expression was controlled by a ~10-kb long SE. ENC1-SEdistal deletion reduced ENC1 expression and inhibited the malignant behavior of BC cells and their resistance to radiotherapy. The binding sites on the ENC1-SE region enriched the shared sequence between TCF4 and ENC1 promoter. Knocking-down TCF4 inhibited luciferase activity and H3K27ac-enriched binding of the ENC1-SE region. Additionally, SE-driven ENC1 overexpression mediated by TCF4 may have clinical implications in radio-resistance in BC patients. Our findings indicated that ENC1 overexpression is mediated by SE and the downstream TCF4 to potentiate the Hippo/YAP1/TAZ pathway. Targeting this axis might be a therapeutic strategy for overcoming BC radio-resistance.

Up-regulated circBACH2 contributes to cell proliferation, invasion, and migration of triple-negative breast cancer.

An increasing amount of evidence has proven the vital role of circular RNAs (circRNAs) in cancer progression. However, there remains a dearth of knowledge on the function of circRNAs in triple-negative breast cancer (TNBC). Utilizing a circRNA microarray dataset, four circRNAs were identified to be abnormally expressed in TNBC. Among them, circBACH2 was most significantly elevated in TNBC cancerous tissues and its high expression was positively correlated to the malignant progression of TNBC patients. In normal human mammary gland cell line, the overexpression of circBACH2 facilitated epithelial to mesenchymal transition and cell proliferation. In TNBC cell lines, circBACH2 knockdown suppressed the malignant progression of TNBC cells. Mechanistically, circBACH2 sponged miR-186-5p and miR-548c-3p, thus releasing the C-X-C chemokine receptor type 4 (CXCR4) expression. The interference of miR-186-5p/miR-548c-3p efficiently promoted the cell proliferation, migration, and invasion suppressed by circBACH2 knockdown in the TNBC cell lines. Finally, circBACH2 knockdown repressed the growth and lung metastasis of TNBC xenografts in nude mice. In summary, circBACH2 functions as an oncogenic circRNA in TNBC through a novel miR-186-5p/miR-548c-3p/CXCR4 axis.

TRIM3 inhibits P53 signaling in breast cancer cells.

BACKGROUND: Beast cancer is the most common women cancer worldwide, while two third of them are ER alpha positive breast cancer. Among the ER alpha positive breast cancer, about 80% are P53 wild type, indicating the potential tumor suppression role in ER alpha positive breast cancer. Since P53 is an important safeguard to inhibit cell malignant transformation, reactivating P53 signaling could a plausible approach to treat breast cancer. METHODS: TRIM3 protein levels were measured by western blot, while the P53 classical target genes were measured by real-time PCR. WST1 assay were used to measure cell proliferation, while cleaved caspase-3 was used to detect cell apoptosis. Protein stability and ubiquitin assay were used to detect the P53 protein ubiquitin and stability. The immuno-precipitation assays were used to detect the protein interactions. Immuno-staining was used to detect the protein localization of P53 and TRIM3, while the ubiquitin-based immuno-precipitation assays were used to detect the specific ubiquitination manner of P53. RESULTS: In our study, we identified TRIM3 as an endogenous inhibitor for P53 signaling. TRIM3 depletion inhibited breast cancer cell proliferation and promoted apoptosis. In addition, TRIM3 depletion increased P53 protein level in breast cancer cell. Further investigation showed that TRIM3 could associate with P53 and promote P53 K48-linked ubiquitination and degradation. CONCLUSION: Our study identified a novel post-translational modification mechanism between TRIM3 and P53. TRIM3 depletion or blockage could be a promising strategy to rescue P53 signaling and inhibit breast cancer progression.

Exosome-mediated transfer of long noncoding RNA H19 induces doxorubicin resistance in breast cancer.

Development of the acquired resistance is one major obstacle during chemotherapy for cancer patients. Exosomes mediate intercellular communication and cause environmental changes in tumor progression by transmitting active molecules. In this study, the role of long noncoding RNA H19 within exosomes is elucidated in terms of regulating doxorubicin (DOX) resistance of breast cancer. As a result, increased H19 expression was observed in DOX-resistant breast cancer cells in comparison with the corresponding parental cells. Suppression of H19 significantly lowered DOX resistance by decreasing cell viability, lowering colony-forming ability, and inducing apoptosis. Moreover, extracellular H19 could be moved to sensitive cells via being incorporated into exosomes. Treating sensitive cells with exosomes from resistant cells increased the chemoresistance of DOX, while downregulation of H19 in sensitive cells abated this effect. Taken together, H19 could be delivered by exosomes to sensitive cells, leading to the dissemination of DOX resistance. Our finding highlights the potential of exosomal H19 as a molecular target to reduce DOX resistance.

lncRNA GHET1 knockdown suppresses breast cancer activity in vitro and in vivo.

Long non-coding RNA gastric carcinoma high-expressed transcript 1 (lncRNA GHET1) is highly expressed in many tumors. The aim of the present study was to determine whether GHET1 inhibition decreases growth and metastasis of MCF-7 breast cancer cells by modulating epidermal growth factor receptor (EGFR) expression. In vitro, lncRNA GHET1 knockdown suppressed cell proliferation, migration, and invasion and enhanced cell apoptosis by maintaining MCF-7 cells in the G1 phase of the cell cycle. Furthermore, lncRNA GHET1 knockdown reduced the expression of EGFR and related proteins. Treatment of mice with a GHET1 inhibitor prevented tumor growth in vivo. The results indicate that lncRNA GHET1 inhibition directly suppresses EGFR expression, significantly inhibiting the downstream PI3K/AKT/Cyclin D1/MMP2/9 pathway. This mechanism may underlie the suppression of breast cancer cell activities including proliferation, migration, and invasion. In conclusion, lncRNA GHET1 knockdown suppresses tumor growth and metastasis by suppressing the activity of EGFR and downstream pathways.

Baicalin Inhibits Cell Viability, Migration and Invasion in Breast Cancer by Regulating miR-338-3p and MORC4.

BACKGROUND: Baicalin is a natural compound from the roots of Scutellaria lateriflora Georgi, which plays anti-cancer role in multiple cancers. However, the exact role and potential underlying mechanism of baicalin in breast cancer (BC) remain poorly understood. METHODS: Thirty BC patients were recruited in this study. MCF-10A, MCF-7 and MDA-MB-231 cells were used to investigate the anti-cancer role of baicalin in vitro. Cell viability, migration, invasion and apoptosis were measured by MTT, trans-well and flow cytometry, respectively. The expression levels of microRNA-338-3p (miR-338-3p) and microrchidia family CW-type zinc-finger 4 (MORC4) were measured by quantitative real-time polymerase chain reaction or Western blot. The interaction between miR-338-3p and MORC4 was explored by luciferase reporter assay and RNA immunoprecipitation. RESULTS: We found that Baicalin treatment inhibited cell viability, migration and invasion but promoted apoptosis of BC cells. The expression of miR-338-3p was decreased in BC tissues and cells and miR-338-3p overexpression suppressed cell viability, migration and invasion but induced apoptosis. MiR-338-3p expression was reversed by baicalin exposure and inhibition of miR-338-3p attenuated the role of baicalin in viability, apoptosis, migration and invasion. MORC4 mRNA level was increased in BC tissues and cells, which was decreased by baicalin exposure. MORC4 was a target of miR-338-3p and its overexpression alleviated the effect of miR-338-3p on cell viability, apoptosis, migration and invasion. CONCLUSION: In conclusion, baicalin suppressed cell viability, migration and invasion but promoted apoptosis in BC cells by regulating miR-338-3p and MORC4, indicating the promising pharmacological value of baicalin in BC treatment.

miR-506 attenuates methylation of lncRNA MEG3 to inhibit migration and invasion of breast cancer cell lines via targeting SP1 and SP3.

BACKGROUND: Breast cancer has been the first death cause of cancer in women all over the world. Metastasis is believed to be the most important process for treating breast cancer. There is evidence that lncRNA MEG3 functions as a tumor suppressor in breast cancer metastasis. However, upstream regulation of MEG3 in breast cancer remain elusive. Therefore, it is critical to elucidate the underlying mechanism upstream MEG3 to regulate breast cancer metastasis. METHODS: We employed RT-qPCR and Western blot to examine expression level of miR-506, DNMT1, SP1, SP3 and MEG3. Besides, methylation-specific PCR was used to determine the methylation level of MEG3 promoter. Wound healing assay and transwell invasion assay were utilized to measure migration and invasion ability of breast cancer cells, respectively. RESULTS: SP was upregulated while miR-506 and MEG3 were downregulated in breast tumor tissue compared to adjacent normal breast tissues. In addition, we found that miR-506 regulated DNMT1 expression in an SP1/SP3-dependent manner, which reduced methylation level of MEG3 promoter and upregulated MEG3 expression. SP3 knockdown or miR-506 mimic suppressed migration and invasion of MCF-7 and MDA-MB-231 cells whereas overexpression of SP3 compromised miR-506-inhibited migration and invasion. CONCLUSIONS: Our data reveal a novel axis of miR-506/SP3/SP1/DNMT1/MEG3 in regulating migration and invasion of breast cancer cell lines, which provide rationales for developing effective therapies to treating metastatic breast cancers.

microRNA-30d mediated breast cancer invasion, migration, and EMT by targeting KLF11 and activating STAT3 pathway.

miR-30d has been shown to play pivotal roles in cancer development, and has the potential to act as a diagnostic biomarker and therapeutic target in breast cancer. However, the specific function and molecular mechanism of miR-30d in breast cancer cell growth and metastasis is still unknown. The present study seeks to shed light on the potential contribution of the MiR-30d-KLF-11-STAT3 pathway in breast cancer. The results revealed that miR-30d levels were markedly increased in the breast cancer cell lines BT474, MDA-MB-231, HCC197, and MDA-MB-468 compared with the non-tumor mammary gland MCF10A cell line. Furthermore, the miR-30d mimic increased BT474 and MDA-MB-231 breast cancer cell survival, inhibited apoptosis and increased Bcl-2 expression, whilst inhibited Bax protein levels. miR-30d mimics promote BT474 and MDA-MB-231 cell migration, invasion, and mediate the EMT phenotype. However, miR-30d inhibitors reverse all of the effects of miR-30d mimics on breast cancer cell biology. Also, we observed that KLF-11 is a direct target of miR-30d and KLF-11 and pSTAT3 expression are determined by miR-30d. Finally, the results suggest that miR-30d plays essential roles in breast cancer cells in a manner that is dependent on the levels of KLF-1 and pSTAT3. In summary, miR-30d appears to be a novel diagnostic biomarker and treatment target in breast cancer.

TOX high mobility group box family member 3 rs3803662 and breast cancer risk: A meta-analysis.

AIMS: Some studies suggested that TOX high mobility group box family member 3 (TOX3) rs3803662 polymorphism was associated with the risk of breast cancer. However, the results were controversy. Therefore, in order to derive a more comprehensive estimation of the association between TOX3 rs3803662 polymorphism and breast cancer risk, we conducted a meta-analysis to investigate this relationship. MATERIALS AND METHODS: An electronic literature search was conducted using the following database: PubMed, EMBASE, and China National Knowledge Infrastructure till to March 31, 2015. The strength of the associations between the TOX3 rs3803662 polymorphism and breast cancer risk in per alle model was measured by odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: A statistically significant association between TOX3 rs3803662 polymorphism and breast cancer risk was fond. The data showed that TOX3 rs3803662 polymorphism could increase the risk of breast cancer (OR = 1.20; 95% CI: 1.16-1.25; P < 0.00001). In the subgroup analysis of race, Caucasians, Asians, and Hispanics also showed increased breast cancer risk (OR = 1.21; 95% CI: 1.17-1.25; P < 0.00001; OR = 1.20; 95% CI: 1.08-1.33; P = 0.0004; OR = 1.32; 95% CI: 1.12-1.57; P = 0.001). However, African-Americans with TOX3 rs3803662 polymorphism showed decreased breast cancer risk (OR = 0.95; 95% CI: 0.86-1.04; P = 0.28), although the result was not significant. When considered estrogen receptor (ER) status, we found that ER + subjects and ER - subjects all had increased breast cancer risk, if they carried this polymorphism (OR = 1.27; 95% CI: 1.19-1.35; P < 0.00001; OR = 1.12; 95%CI: 1.08-1.17; P < 0.00001). Similarly, both progesterone receptor-positive (PR +) subjects and PR - subjects all showed increased breast cancer risk, if they carried this polymorphism (OR = 1.32; 95% CI: 1.17-1.49; P < 0.00001; OR = 1.15; 95% CI: 1.09-1.23; P < 0.00001). CONCLUSIONS: This meta-analysis suggested that TOX3 rs3803662 polymorphism was associated with increased breast cancer risk.

Long non-coding RNA PVT1 facilitates cell proliferation by epigenetically regulating FOXF1 in breast cancer.

Background: plasmacytoma variant translocation 1 (PVT1) has been identified as an oncogenic long non-coding RNA (lncRNA) in multiple cancers including breast cancer. However, its molecular basis has not been exhaustively elucidated. Methods: RT-qPCR assay was used to detect PVT1 expression in tissues and cells. The effect of PVT1 and FOXF1 on breast cancer cell proliferation was assessed by MTT, colony formation and cell cycle assays. Cell apoptotic rate was measured by flow cytometry via double-staining of Annexin V-FITC and PI. The protein expression patterns of forkhead box f1 (FOXF1) and enhancer of zeste homolog 2 (EZH2) were detected using western blot assays. The subcellular location of PVT1 was analyzed using subcellular fractionation assays. The interaction between PVT1 and EZH2 were demonstrated by RNA-protein pull down and RIP assays. ChIP assay was used to explore whether PVT1 affected FOXF1 expression by recruiting EZH2. In vivo assays were performed to further investigate the roles of PVT1 in breast cancer tumorigenesis. Results: PVT1 expression was elevated in breast cancer tissues and cells. Moreover, higher PVT1 level was positively associated with aggressive pathological status and poor prognosis of breast cancer. PVT1 knockdown suppressed proliferation and induced apoptosis in breast cancer cells. PVT1 silenced FOXF1 expression by recruiting EZH2 to the promoter region of FOXF1, resulting in the increase of H3K27me3 level. EZH2 inhibitor EPZ005687 counteracted PVT1-mediated enrichment effect on H3K27me3 and EZH2 to FOXF1 promoter region. FOXF1 overexpression hampered proliferation and facilitated apoptosis in breast cancer cells. Furthermore, down-regulation of FOXF1 partly abrogated PVT1-knockdown-mediated anti-proliferation and pro-apoptosis effect in breast cancer cells. Finally, PVT1 deficiency suppressed tumor growth by promoting FOXF1 expression in vivo. Conclusion: PVT1 promoted cell proliferation and suppressed apoptosis by epigenetically silencing FOXF1 expression through EZH2 in breast cancer.

Galectin-1 knockdown improves drug sensitivity of breast cancer by reducing P-glycoprotein expression through inhibiting the Raf-1/AP-1 signaling pathway.

Galectin-1 (Gal-1), a member of the galectin family of carbohydrate binding proteins, plays a pivotal role in various cellular processes of tumorigenesis. The regulatory effect of Gal-1 on multidrug resistance (MDR) breast cancer cells is still unclear. qRT-PCR and western blot showed that Gal-1 and MDR gene 1 (MDR1) were both highly expressed in breast tumor tissues and cell lines. MTT assay and flow cytometry revealed that Gal-1 knockdown improved sensitivity to paclitaxel (PTX) and adriamycin (ADR) in MCF-7/PTX and MCF-7/ADR cells via inhibition of cell viability and promotion of cell apoptosis, while MDR1 overexpression weakened the sensitivity to PTX and ADR induced by Gal-1 knockdown. Furthermore, the negative effects of Gal-1 knockdown on sensitivity to PTX and ADR in MCF-7/PTX and MCF-7/ADR cells were revealed to be mediated via the suppression of Raf-1/AP-1 pathway. In conclusion, Gal-1 knockdown dramatically improved drug sensitivity of breast cancer by reducing P-glycoprotein (P-gp) expression via inhibiting the Raf-1/AP-1 pathway, providing a novel therapeutic target to overcome MDR in breast cancer.

microRNA-761 induces aggressive phenotypes in triple-negative breast cancer cells by repressing TRIM29 expression.

PURPOSE: Despite advances that have been made in systemic chemotherapy, the prognosis of advanced triple-negative breast cancer (TNBC) patients is still poor. The identification of key factors governing TNBC development is considered imperative for the development of novel effective therapeutic approaches. Previously, it has been reported that microRNA (miR)-761 may act as either a tumor suppressor or as an oncogene in different types of cancer. Here, we aimed at assessing the biological role of this miRNA in TNBC. METHODS: First, we measured the expression of miR-761 in primary breast cancer tissues and breast cancer-derived cell lines using qRT-PCR. Subsequently, over-expression and silencing experiments were performed to determine the role of miR-761 in TNBC cell proliferation, colony formation, migration and invasion in vitro. The in vivo role of miR-761 in TNBC growth and metastasis was determined in mouse models. Bioinformatics analyses, dual-luciferase reporter assays, Western blot analyses and rescue experiments were performed to identify miR-761 target gene(s). RESULTS: We found that miR-761 was up-regulated in primary breast cancer tissues and its derived cell lines and, particularly, in TNBC tissues and cell lines. We also found that exogenous miR-761 over-expression augmented in vitro TNBC cell proliferation, colony formation, migration and invasion, whereas miR-761 down-regulation impaired these features. In vivo, we found that miR-761 over-expression facilitated TNBC growth and lung metastasis. Mechanistically, miR-761 was found to negatively regulate the expression of tripartite motif-containing 29 (TRIM29) in TNBC cells by binding to the 3'-untranslated region of its mRNA. In conformity with these results, a significant negative correlation between miR-761 expression and TRIM29 protein expression was noted in primary TNBC tissues (r = -0.452, p = 0.0126). We also found that exogenous TRIM29 over-expression reversed the proliferative and invasive capacities of TNBC cells. CONCLUSIONS: Our data indicate that miR-761 acts as an oncogene in TNBC. This mode of action can, at least partially, be ascribed to the down-regulation of its target TRIM29. We suggest that miR-761 may serve as a promising therapeutic target for TNBC.

MicroR-760 suppresses cancer stem cell subpopulation and breast cancer cell proliferation and metastasis: By down-regulating NANOG.

BACKGROUND AND OBJECTIVE: Emerging evidences suggest that cancer stem cells are responsible for tumor aggressive, metastasis and therapeutic resistance. To data, the mechanism underlying breast cancer stem cell (BCSC) population within tumor metastasis remains to be fully elucidated. The current study was to investigate the potential role of microRNA-760 (miR-760) and its associated target gene in population and metastasis of BCSC. METHODS: Characteristic BCSCs surface markers (CD44(+)/CD24(-/low)) were determined by flow cytometry in breast cancer MCF-7 and BT-549 cells. Quantitative RT-PCR was used to evaluate miR-760 and NANOG mRNA expression. Expression of NANOG protein was determined using western blot. Cell proliferation was determined by MTT assay. The model of breast cancer cell xenograft was used to evaluate the effect of miR-760 on tumor growth. RESULTS: BT-549 cell has substantially more CD44(+)/CD24(-/low) subpopulation than MCF-7 cell. Moreover, BT-549 cell expressed lower level of miR-760 and higher level of NANOG than MCF-7cell. By result from cellular miR-760 modulation, we found that miR-760 overexpression suppressed CD44(+)/CD24(-/low) population as well as inhibited cell proliferation and migration of BT-549. On the contrary, knockdown of miR-760 promoted CD44(+)/CD24(-/low) population and migration of MCF-7 cells. By luciferase reporter assay, miR-760 was proved to be functional associated with NANOG via regulating its expression. This functional interaction was showed to be involved in controlling proliferation and migration of MCF-7 and BT-549 cell. CONCLUSION: These data suggest that the target of miR-760/NANOG axis may represent a new therapeutic approach to suppress breast cancer stem cell subpopulation thereby prevent cancer metastasis.

MicroRNA-21 induces breast cancer cell invasion and migration by suppressing smad7 via EGF and TGF-ß pathways.

MicroRNA-21 (miR-21) upregulation, smad family member 7 (smad7) downregulation, epidermal growth factor (EGF) and transforming growth factor-ß (TGF-ß) actions contribute to breast cancer cell aggressiveness. However, their correlation and the relevant molecular mechanisms involved remain to be elucidated. The present study was undertaken to determine the association of miR-21, smad7, EGF and TGF-ß with breast cancer cell invasion and migration and to identify the molecular mechanisms involved using immunohistochemistry and western blot analysis. In the present study, the plasma miR-21 levels were significantly increased in patients with breast cancer, as compared to the controls. Smad7 was confirmed to be a direct target of miR-21, by luciferase reporter and western blot assays. The downregulation of smad7 by miR-21 or sismad7 enhanced EGF-dependent invasion and migration, as well as TGF-ß-dependent invasion and migration. The actions of miR-21 were abrogated by expressing a modified smad7 cDNA resistant to miR-21. Moreover, miR-21, EGF and TGF-ß combined to markedly increase cancer cell invasion and migration, and this effect was blocked by the combination of erlotinib (an EGF receptor kinase inhibitor) and SB505124 (a type I TGF-ß receptor inhibitor). A lower smad7 expression was identified in poorly differentiated breast cancers, as compared to well- to moderately differentiated breast cancers. Notably, antagonism of miR-21 decreased breast cancer cell proliferation and tumor growth in mouse models. In conclusion, our results demonstrated that plasma miR-21 levels may serve as a diagnostic marker in breast cancers, whereas miR-21 promotes breast cancer cell proliferation and invasion by suppressing smad7, which enhances EGF and TGF-ß pathways.

Overexpression of miR-206 suppresses glycolysis, proliferation and migration in breast cancer cells via PFKFB3 targeting.

miRNAs, sorting as non-coding RNAs, are differentially expressed in breast tumor and act as tumor promoters or suppressors. miR-206 could suppress the progression of breast cancer, the mechanism of which remains unclear. The study here was aimed to investigate the effect of miR-206 on human breast cancers. We found that miR-206 was down-regulated while one of its predicted targets, 6-Phosphofructo-2-kinase (PFKFB3) was up-regulated in human breast carcinomas. 17ß-estradiol dose-dependently decreased miR-206 expression as well as enhanced PFKFB3 mRNA and protein expression in estrogen receptor α (ERα) positive breast cancer cells. Furthermore, we identified that miR-206 directly interacted with 3'-untranslated region (UTR) of PFKFB3 mRNA. miR-206 modulated PFKFB3 expression in MCF-7, T47D and SUM159 cells, which was influenced by 17ß-estradiol depending on ERα expression. In addition, miR-206 overexpression impeded fructose-2,6-bisphosphate (F2,6BP) production, diminished lactate generation and reduced cell proliferation and migration in breast cancer cells. In conclusion, our study demonstrated that miR-206 regulated PFKFB3 expression in breast cancer cells, thereby stunting glycolysis, cell proliferation and migration.