Behavior Of Breast Cancer Cells Research Articles

Behavior of breast cancer cells under oxygen concentration gradients in a microfluidic device.

The tumor microenvironment (TME) is known as a chronic hypoxic environment, with spatiotemporal variation in oxygen concentration depending on the distance from blood vessels and the blood supply. In our previous studies, cancer cell behavior was observed under hypoxic conditions with spatial variation of oxygen concentration (oxygen concentration gradients); however, that under oxygen concentration gradients at low oxygen levels found in the TME has not been studied. In this study, we investigated the behavior of breast cancer cells at various oxygen concentration gradients, generated using a microfluidic device with oxygen concentration controllability. The results showed that cell distribution was altered in response to oxygen concentration, and tended to increase in a specific region at around 5% O2. Evaluation of changes in cell numbers due to proliferation, migration, and cell death indicated that proliferation strongly affected cell distribution.

Downregulation of circ_0119412 expression inhibits malignant progression of breast cancer by targeting the miR-1205/GALNT6 pathway in vivo and in vitro

IntroductionAberrant circular RNA (circRNA) expression is associated with development of breast cancer. In this study, we aimed to assess the anti-proliferative effect of <i>circ_0119412</i> knockdown on breast cancer cells.Material and methodsTumor and adjacent normal tissues were collected from 35 patients with invasive breast cancer (mean age: 56 years; mean tumor size: 2 cm; 46% patients with TNM I and II stages). The levels of <i>circ_0119412</i>, microRNA (<i>miR</i>)-1205, and N-acetylgalactosaminyltransferase 6 (<i>GALNT6</i>) were determined using reverse transcription-quantitative polymerase chain reaction. Cell proliferation and invasion were assessed using cell counting kit-8 and transwell assays, respectively. Cell apoptosis was assessed using flow cytometry. Moreover, the targeting relationships of <i>miR-1205</i> with <i>circ_0119412</i> and <i>GALNT6</i> were determined using dual-luciferase reporter and RNA immunoprecipitation assays. Furthermore, tumor growth was observed in an animal model in vivo.ResultsWe found that <i>circ_0119412</i> expression levels were upregulated in breast cancer tumor specimens and cell lines. Downregulation of <i>circ _0119412</i> inhibited the invasion and proliferation, while enhancing the apoptosis of breast cancer cells. Furthermore, <i>circ_0119412</i> knockdown suppressed tumor growth in vivo. Notably, <i>miR-1205</i> was identified as a downstream target of <i>circ_0119412</i>. Downregulation of <i>circ_0119412</i> suppressed the aggressive behavior of breast cancer cells by targeting <i>miR-1205</i>. Moreover, <i>GALNT6</i> was the downstream target of <i>miR-1205</i>. Inhibition of <i>miR-1205</i> aggravated the malignant behavior of breast cancer cells by increasing <i>GALNT6</i> expression.ConclusionsOur findings suggest that the downregulation of <i>circ_0119412</i> inhibits breast cancer progression, at least in part, by targeting the <i>miR-1205/GALNT6</i> pathway.

LINC00504 Promotes the Malignant Biological Behavior of Breast Cancer Cells by Upregulating HMGB3 via Decoying MicroRNA-876-3p [Retraction

[This retracts the article DOI: 10.2147/CMAR.S276290.].

Circ_0069094 regulates malignant phenotype and paclitaxel resistance in breast cancer cells via targeting the miR-136-5p/YWHAZ axis.

Breast cancer is one of the most malignant cancers. Increasing evidence suggests that circular RNAs (circRNAs) are involved in breast cancer progression through sponging microRNA (miRNA). However, the underlying molecular mechanisms of circ_0069094 in breast cancer are unclear. This study aimed to reveal the effect of the circ_0069094/miR-136-5p/tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ) pathway on the malignant progression of breast cancer. The quantitative real-time polymerase chain reaction and western blot were used to assess the expression of circRNA/miRNA/mRNA. The functional effects of circ_0069094 on the cell processes of breast cancer were investigated by cell counting kit-8, colony-forming assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, and transwell invasion assay. The interactions among circ_0069094, miR-136-5p, and YWHAZ were assessed by dual-luciferase reporter assay. A xenograft experiment was performed to determine the effects of circ_0069094 on tumor formation. Circ_0069094 was overexpressed in paclitaxel (PTX)-resistant breast cancer tissues and cells, and the silencing of circ_0069094 decreased tumor growth, cell proliferation and cell invasion while increasing PTX sensitivity and cell apoptosis in PTX-resistant cells. In addition, miR-136-5p was a target of circ_0069094, and miR-136-5p inhibition abolished circ_0069094 knockdown-induced effects in PTX-resistant cells. MiR-136-5p expression was decreased in PTX-resistant breast cancer tissues and cells, and the overexpression of miR-136-5p suppressed the malignant behaviors of breast cancer cells by targeting YWHAZ. Importantly, circ_0069094 regulated YWHAZ expression in breast cancer by targeting miR-136-5p. Circ_0069094 silencing improved PTX sensitivity in breast cancer progression through competitively sponging miR-136-5p.

Actin cytoskeleton depolymerization increases matrix metalloproteinase gene expression in breast cancer cells by promoting translocation of cysteine-rich protein 2 to the nucleus.

The actin cytoskeleton plays a critical role in cancer cell invasion and metastasis; however, the coordination of its multiple functions remains unclear. Actin dynamics in the cytoplasm control the formation of invadopodia, which are membrane protrusions that facilitate cancer cell invasion by focusing the secretion of extracellular matrix-degrading enzymes, including matrix metalloproteinases (MMPs). In this study, we investigated the nuclear role of cysteine-rich protein 2 (CRP2), a two LIM domain-containing F-actin-binding protein that we previously identified as a cytoskeletal component of invadopodia, in breast cancer cells. We found that F-actin depolymerization stimulates the translocation of CRP2 into the nucleus, resulting in an increase in the transcript levels of pro-invasive and pro-metastatic genes, including several members of the MMP gene family. We demonstrate that in the nucleus, CRP2 interacts with the transcription factor serum response factor (SRF), which is crucial for the expression of MMP-9 and MMP-13. Our data suggest that CRP2 and SRF cooperate to modulate of MMP expression levels. Furthermore, Kaplan-Meier analysis revealed a significant association between high-level expression of SRF and shorter overall survival and distant metastasis-free survival in breast cancer patients with a high CRP2 expression profile. Our findings suggest a model in which CRP2 mediates the coordination of cytoplasmic and nuclear processes driven by actin dynamics, ultimately resulting in the induction of invasive and metastatic behavior in breast cancer cells.

A Novel circ_0104345/miR-876-3p/ZBTB20 Axis Regulates the Proliferation, Migration, Invasion, and Apoptosis of Breast Cancer Cells.

Breast cancer (BC) is one of the most common malignant tumors in women. CircRNA/miRNA/mRNA regulatory axes have been shown to be involved in the pathogenesis of BC. Here, we sought to analyze the functional mechanism of circ_0104345 in BC. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the levels of circ_0104345, miR-876-3p and zinc finger and BTB domain containing 20 (ZBTB20) mRNA. Cell Counting Kit-8 (CCK8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to test cell viability and proliferation, respectively. Cell migration was tested by wound healing assay, and cell invasion was examined by transwell assay. Tube formation ability was tested by angiogenesis assay. Flow cytometry was applied for cell apoptosis. Western blot assay was utilized to measure the protein expression. The relationship between miR-876-3p and circ_0104345 or ZBTB20 was identified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Xenografts in mice were conducted to analyze the effect of sh-circ_0104345 on tumor growth in vivo. Circ_0104345 and ZBTB20 were upregulated and miR-876-3p expression was decreased in BC. Circ_0104345 knockdown inhibited cell proliferation, migration, invasion, and enhanced cell apoptosis. MiR-876-3p was targeted by circ_0104345. MiR-876-3p depletion reversed the effects of circ_0104345 downregulation on the progression of BC cells. ZBTB20 was regulated by circ_0104345 through miR-876-3p. The effects of miR-876-3p on BC cell behaviors were restored by ZBTB20 increase. The results of in vivo experiments indicated that silencing of circ_0104345 blocked the growth of xenograft tumors. In this study, we demonstrated, for the first time, the crucial regulation of the new circ_0104345/miR-876-3p/ZBTB20 axis in the biological phenotypes of BC cells.

Long noncoding RNA HOTAIR promotes breast cancer development through the lncRNA HOTAIR/miR-1/GOLPH3 axis.

The lncRNA HOTAIR is frequently overexpressed in breast cancer tissues and plays an important role in the development of breast cancer. Here, we investigated the effect of the lncRNA HOTAIR on the biological behaviour of breast cancer cells and its molecular mechanism. We investigated the level of HOTAIR in breast cancer and its clinical pathological characteristics by bioinformatic methods. Then, we evaluated the effects of HOTAIR and miRNA-1 expression on the biological behaviour of breast cancer cells by qPCR, Cell Counting Kit-8 (CCK-8) assay, clonogenic assays, Transwell assay and flow cytometry for cell proliferation, invasion migration and apoptosis, and cell cycle analysis. Finally, the target genes of the lncRNA HOTAIR/miR-1/GOLPH3 regulatory axis were validated by luciferase reports. The expression of HOTAIR in breast cancer tissues was significantly higher than that in normal breast tissues (P < 0.05). Silencing of HOTAIR suppressed cell proliferation, invasion and migration, promoted apoptosis and induced G1 phase block in breast cancer (P < 0.0001). We also verified that miR-1 is a target of HOTAIR and that GOLPH3 is a target of miR-1 by luciferase reporter assays (P < 0.001). The expression of HOTAIR was significantly elevated in breast cancer tissues. Reducing the expression of HOTAIR inhibited the proliferation, invasion and migration of breast cancer cells and promoted apoptosis, and the mechanism was mainly the effect of the lncRNA HOTAIR/miR-1/GOLPH3 regulatory axis on the biological behaviour of breast cancer cells.

Silencing RAB27a inhibits proliferation, invasion and adhesion of triple-negative breast cancer cells

To investigate the effect of inhibition of RAB27 protein family, which plays a pivotal role in exosome secretion, on biological behaviors of triple-negative breast cancer cells. Quantitative real-time PCR and Western blotting were used to examine the expressions of RAB27 family and exosome secretion in 3 triple-negative breast cancer cell lines (MDA-MB-231, MDA-MB-468, and Hs578T) and a normal breast epithelial cell line (MCF10A). The effect of small interfering RNA (siRNA)-mediated silencing of RAB27a and RAB27b on exosome secretion in the 3 breast cancer cell lines was detected using Western blotting, and the changes in cell proliferation, invasion and adhesion were evaluated. Compared with normal breast epithelial cells, the 3 triple-negative breast cancer cell lines exhibited more active exosome secretion (P < 0.001) and showed significantly higher expressions of RAB27a and RAB27b at both the mRNA and protein levels (P < 0.01). Silencing of RAB27a in the breast cancer cells significantly down-regulated exosome secretion (P < 0.001), while silencing of RAB27b did not significantly affect exosome secretion. The 3 breast cancer cell lines with RAB27a silencing-induced down-regulation of exosome secretion showed obvious inhibition of proliferation, invasion and adhesion (P < 0.01) as compared with the cell lines with RAB27b silencing. RAB27a plays central role in the exosome secretion in triple-negative breast cancer cells, and inhibiting RAB27a can inhibit the proliferation, invasion and adhesion of the cells.

Revisiting the Syndecans: Master Signaling Regulators with Prognostic and Targetable Therapeutic Values in Breast Carcinoma

Syndecans (SDC1 to 4), a family of cell surface heparan sulfate proteoglycans, are frequently expressed in mammalian tissues. SDCs are aberrantly expressed either on tumor or stromal cells, influencing cancer initiation and progression through their pleiotropic role in different signaling pathways relevant to proliferation, cell-matrix adhesion, migration, invasion, metastasis, cancer stemness, and angiogenesis. In this review, we discuss the key roles of SDCs in the pathogenesis of breast cancer, the most common malignancy in females worldwide, focusing on the prognostic significance and molecular regulators of SDC expression and localization in either breast tumor tissue or its microenvironmental cells and the SDC-dependent epithelial-mesenchymal transition program. This review also highlights the molecular mechanisms underlying the roles of SDCs in regulating breast cancer cell behavior via modulation of nuclear hormone receptor signaling, microRNA expression, and exosome biogenesis and functions, as well as summarizing the potential of SDCs as promising candidate targets for therapeutic strategies against breast cancer.

Targeting KK-LC-1 inhibits malignant biological behaviors of triple-negative breast cancer

BackgroundCancer/testis antigens (CTAs) participate in the regulation of malignant biological behaviors in breast cancer. However, the function and mechanism of KK-LC-1, a member of the CTA family, in breast cancer are still unclear.MethodsBioinformatic tools, immunohistochemistry, and western blotting were utilized to detect the expression of KK-LC-1 in breast cancer and to explore the prognostic effect of KK-LC-1 expression in breast cancer patients. Cell function assays, animal assays, and next-generation sequencing were utilized to explore the function and mechanism of KK-LC-1 in the malignant biological behaviors of triple-negative breast cancer. Small molecular compounds targeting KK-LC-1 were also screened and drug susceptibility testing was performed.ResultsKK-LC-1 was significantly highly expressed in triple-negative breast cancer tissues than in normal breast tissues. KK-LC-1 high expression was related to poor survival outcomes in patients with breast cancer. In vitro studies suggested that KK-LC-1 silencing can inhibit triple-negative breast cancer cell proliferation, invasion, migration, and scratch healing ability, increase cell apoptosis ratio, and arrest the cell cycle in the G0–G1 phase. In vivo studies have suggested that KK-LC-1 silencing decreases tumor weight and volume in nude mice. Results showed that KK-CL-1 can regulate the malignant biological behaviors of triple-negative breast cancer via the MAL2/MUC1-C/PI3K/AKT/mTOR pathway. The small-molecule compound Z839878730 had excellent KK-LC-1 targeting ability and cancer cell killing ability. The EC50 value was 9.7 μM for MDA-MB-231 cells and 13.67 µM for MDA-MB-468 cells. Besides, Z839878730 has little tumor-killing effect on human normal mammary epithelial cells MCF10A and can inhibit the malignant biological behaviors of triple-negative breast cancer cells by MAL2/MUC1-C/PI3K/AKT/mTOR pathway.ConclusionsOur findings suggest that KK-LC-1 may serve as a novel therapeutic target for triple-negative breast cancer. Z839878730, which targets KK-LC-1, presents a new path for breast cancer clinical treatment.

Long-Term Simulation of Microgravity Induces Changes in Gene Expression in Breast Cancer Cells.

Microgravity changes the gene expression pattern in various cell types. This study focuses on the breast cancer cell lines MCF-7 (less invasive) and MDA-MB-231 (triple-negative, highly invasive). The cells were cultured for 14 days under simulated microgravity (s-µg) conditions using a random positioning machine (RPM). We investigated cytoskeletal and extracellular matrix (ECM) factors as well as focal adhesion (FA) and the transmembrane proteins involved in different cellular signaling pathways (MAPK, PAM and VEGF). The mRNA expressions of 24 genes of interest (TUBB, ACTB, COL1A1, COL4A5, LAMA3, ITGB1, CD44, VEGF, FLK1, EGFR, SRC, FAK1, RAF1, AKT1, ERK1, MAPK14, MAP2K1, MTOR, RICTOR, VCL, PXN, CDKN1, CTNNA1 and CTNNB1) were determined by quantitative real-time PCR (qPCR) and studied using STRING interaction analysis. Histochemical staining was carried out to investigate the morphology of the adherent cells (ADs) and the multicellular spheroids (MCSs) after RPM exposure. To better understand this experimental model in the context of breast cancer patients, a weighted gene co-expression network analysis (WGCNA) was conducted to obtain the expression profiles of 35 breast cell lines from the HMS LINCS Database. The qPCR-verified genes were searched in the mammalian phenotype database and the human genome-wide association studies (GWAS) Catalog. The results demonstrated the positive association between the real metastatic microtumor environment and MCSs with respect to the extracellular matrix, cytoskeleton, morphology, different cellular signaling pathway key proteins and several other components. In summary, the microgravity-engineered three-dimensional MCS model can be utilized to study breast cancer cell behavior and to assess the therapeutic efficacies of drugs against breast cancer in the future.

Oxymatrine Inhibits Malignant Behaviors of Breast Cancer Cells by Inhibiting miR-188 Expression to Up-Regulate Phosphatase and Tensin Homolog (PTEN)

Oxymatrine has been applied to anti-cancer therapies for various cancers. The present study aimed to investigate the potential impact of miR-188 on breast cancer (BC) cell progression and underlying mechanism. After establishment of a rat model of BC, rats were administered with oxymatrine (4 mg/kg, 8 mg/kg), Xihuang pill (XH) (positive control), and miR-188 mimic (1 mg/kg) followed by analysis of tumor growth, the expression of miR-188, MMP-9, MMP-2, and PTEN, and BC cell behaviors. Oxymatrine significantly decreased tumor incidence and reduced tumor mass (p&lt;0.05) with 8 mg/kg intervention group and positive control group exhibiting higher tumor inhibition rate (p&lt;0.05). In addition, oxymatrine or XH effectively reduced cell proliferation, invasion and migration rate. Of note, compared to 4 mg/kg oxymatrine, 8 mg/kg oxymatrine and XH showed more significantly inhibitory effects on BC cells. Moreover, oxymatrine or XH significantly downregulated miR-188, MMP-9, and MMP-2 and upregulated PTEN. Mechanically, PTEN was indicated as the target of miR-188 with specific binding between them. In conclusion, Oxymatrine inhibits BC cell behaviors through down-regulation of miR-188 to increase PTEN expression. This study might provide a new basis for the management of BC.

MiR-16-5p regulates apoptosis and migration of drug-resistant breast cancer cells by targeting YWHAQ

To examine the role of miR-16-5p in regulating biological behaviors of paclitaxel- resistant breast cancer cells and its molecular mechanism. The expression of miR-16-5p was examined in 13 pairs of breast cancer and adjacent tissues and in parental SKBR-3 cells and paclitaxel-resistant SKBR-3/PR cells using qRT-PCR. The target genes of miR-16- 5p were predicted by bioinformatic analysis, and their targeted binding was tested using luciferase assay. The cells were transfected with a miR-16-5p mimics, a miR-16-5p inhibitor, a specific siRNA targeting YWHAQ (si-YWHAQ), or both the miR-16-5p mimics and si-YWHAQ, and the changes in cellular expressions of YWHAQ, Bcl-2 and Bax were detected using Western blot. The changes in proliferation and migration of the cells were evaluated with CCK-8 assay and Transwell assay, and the cell cycle changes and cell apoptosis were analyzed with flow cytometry. The expression of miR-16-5p was significantly lower in breast cancer tissues than in paired adjacent tissues (P < 0.01). Bioinformatic analysis predicted that YWHAQ was the target gene of miR-16-5p, which was confirmed by luciferase assay. Compared with parental SKBR- 3 cells, SKBR- 3/PR cells showed a lowered level of miR-16-5p expression and an increased expression of YWHAQ. Transfection with the miR-16-5p mimics significantly inhibited YWHAQ expression (P < 0.01), while miR-16-5p inhibitor promoted YWHAQ expression in SKBR-3/PR cells (P < 0.01). The miR-16-5p mimics caused cell cycle arrest in G0/G1 phase (P < 0.0l), suppressed proliferation and migration, and increased apoptosis rate of SKBR-3/PR cells (P < 0.0l). Knocking down YWHAQ also reduced the migration ability of SKBR-3/PR cells and increased cell apoptosis rate. Transfection with either miR-16-5p mimics or si-YWHAQ resulted in increased Bax expression and lowered expressions of YWHAQ and Bcl-2 in the cells. The cells transfected with both miR-16-5p mimics and si-YWHAQ showed obviously suppressed cell migration (P < 0.01) and significantly increased apoptosis rate (P < 0.01). miR-16-5p can modulate the expressions of Bcl- 2 and Bax by targeted regulation of YWHAQ to modify the biological behaviors of paclitaxel-resistant breast cancer cells.

A CAF-Fueled TIMP-1/CD63/ITGB1/STAT3 Feedback Loop Promotes Migration and Growth of Breast Cancer Cells.

Simple SummaryCarcinoma-associated fibroblasts (CAFs) are a major cellular component of the tumor microenvironment and influence cancer cell behavior in numerous ways. A large part of their actions is based on their high secretory activity, leading to the exposure of cancer cells to all kinds of bioactive factors, such as interleukin-6 (IL-6). Here, we present data showing that CAF-derived TIMP-1 activates STAT3 in breast cancer cells in cooperation with CD63 and integrin β1. In turn, STAT3 increases TIMP-1 secretion by breast cancer cells, leading to a TIMP-1/CD63/integrin β1/STAT3 positive feedback loop, which can be further fueled by IL-6. Functionally, this feedback loop is important for the CAF-induced increase in migratory activity and for CAF-induced resistance to the anti-estrogen fulvestrant.TIMP-1 is one of the many factors that CAFs have been shown to secret. TIMP-1 can act in a tumor-supportive or tumor-suppressive manner. The purpose of this study was to elucidate the role of CAF-secreted TIMP-1 for the effects of CAFs on breast cancer cell behavior. Breast cancer cells were exposed to conditioned medium collected from TIMP-1-secreting CAFs (CAF-CM), and the specific effects of TIMP-1 on protein expression, migration and growth were examined using TIMP-1-specifc siRNA (siTIMP1), recombinant TIMP-1 protein (rhTIMP-1) and TIMP-1 level-rising phorbol ester. We observed that TIMP-1 increased the expression of its binding partner CD63 and induced STAT3 and ERK1/2 activation by cooperating with CD63 and integrin β1. Since TIMP-1 expression was found to be dependent on STAT3, TIMP-1 activated its own expression, resulting in a TIMP-1/CD63/integrin β1/STAT3 feedback loop. IL-6, a classical STAT3 activator, further fueled this loop. Knock-down of each component of the feedback loop prevented the CAF-induced increase in migratory activity and inhibited cellular growth in adherent cultures in the presence and absence of the anti-estrogen fulvestrant. These data show that TIMP-1/CD63/integrin β1/STAT3 plays a role in the effects of CAFs on breast cancer cell behavior.

The Role of 5' Adenosine Monophosphate-Activated Protein Kinase in the Chemo-Sensitivity and Metabolic Behaviour of Breast Cancer Cells Exposed to Hypoxia and Hyperglycaemia

Background: 5' adenosine monophosphate-activated protein kinase (AMPK) is a key enzyme for maintaining energy homeostasis in the cell and is associated with many downstream targets of metabolic processes such as mTORC1, p53 and fatty acid synthase (FASN) and insulin-like growth factor binding protein-2 (IGFBP-2).&#x0D; Aim: To investigate the interactions between AMPK, FASN and IGFBP-2 and how the activity of AMPK affects the metabolism and response of breast cancer cells to chemotherapy with changes in oxygenation and under different glucose concentrations.&#x0D; Methods: MCF-7 breast cancer cells were exposed to different glucose levels (5mM and 25mM) in the presence or absence of doxorubicin under normoxic and hypoxic conditions with and without AMPK silenced using siRNA. Changes in protein abundance were monitored using Western Immunoblotting. Cell death was measured by the Muse® Cell Analyser using a count and viability assay. Hypoxia was chemically induced using cobalt chloride or with low levels of oxygen (2%). Lactate and citrate levels were measured using commercially available kits.&#x0D; Results: In normoxic conditions, AMPK activity was higher in normal levels of glucose (5mM) compared with high levels of glucose (25mM). Under hypoxic conditions, AMPK phosphorylation remained high in 5mM glucose with levels in 25 mM glucose being equivalent. Upregulation of AMPK in normoxic and hypoxic conditions was associated with a reduction in FASN and IGFBP-2, which resulted in a better response to chemotherapy. Moreover, the cells increased the production of lactate and reduced production of citrate under normoxic conditions in 25mM glucose compared to 5mM glucose. Silencing AMPK under normoxic conditions or inducing hypoxia promoted a more glycogenic phenotype. However, silencing AMPK under hypoxic conditions reduced levels of lactate comparable to normoxic levels. The citrate profile was unaffected by silencing AMPK or altering levels of oxygen.&#x0D; Conclusions: AMPK plays an important role in regulating metabolic signalling and this alters the sensitivity of breast cancer cells to chemotherapy.

Hsa_circ_0097922 promotes tamoxifen resistance and cell malignant behaviour of breast cancer cells by regulating ACTN4 expression via miR-876-3p.

An increasing number of findings have verified the critical roles of circular RNAs (circRNAs) in human cancers, and chemotherapy resistance is a poor prognostic factor for breast cancer (BC). This study is designed to explore the function of hsa_circ_0097922 in the tamoxifen resistance of breast cancer. Hsa_circ_0097922, microRNA-876-3p (miR-876-3p), and alpha-actinin 4 (ACTN4) level were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell survival, proliferation, apoptosis, migration and invasion were detected by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry, wound healing and Transwell assays. Protein levels of proliferating cell nuclear antigen (PCNA), B-cell lymphoma-2 (Bcl-2), cleaved caspase 3, matrix metalloproteinase 9 (MMP9), and ACTN4 were determined using western blot assay. Using bioinformatics software, the binding between miR-876-3p and hsa_circ_0097922 or ACTN4 was predicted, followed by confirmation by RNA immunoprecipitation (RIP) and RNA pull-down assays. A xenograft tumour model in vivo analysed the biological role of hsa_circ_0097922 on BC tumour growth and drug resistance. Hsa_circ_0097922 and ACTN4 were increased, and miR-876-3p was decreased in tamoxifen resistance BC cells. Moreover, hsa_circ_0097922 knockdown can block BC cell malignant behaviour and tamoxifen resistance in vitro. Mechanically, hsa_circ_0097922 acted as a sponge of miR-876-3p to regulate ACTN4 expression. Hsa_circ_0097922 silencing increased the drug sensitivity of BC in vivo. Hsa_circ_0097922 might regulate BC cell malignant behaviour and tamoxifen resistance partly by regulating the miR-876-3p/ACTN4 axis, hinting at a promising therapeutic target for the BC treatment.

Long Non-coding RNA LINC01224 Promotes the Malignant Behaviors of Triple Negative Breast Cancer Cells via Regulating the miR-193a-5p/NUP210 Axis.

Triple negative breast cancer (TNBC) is a prevalent malignant tumor in women and is characterized by high incidence and mortality. Current evidence has suggested that multiple long noncoding RNAs (lncRNAs) play regulatory roles in TNBC, while the specific mechanism of LINC01224 in TNBC remains unclear. In this study, LINC01224 was highly expressed in TNBC cells. Moreover, LINC01224 downregulation inhibited TNBC cell proliferation, migration, and invasion, and promoted cell apoptosis. Additionally, LINC01224 stabilized NUP210 mRNA through interaction with miR-193a-5p, thereby aggravating the malignant phenotypes of TNBC. Overall, LINC01224 functions as a tumor promoter for TNBC.

MiR‑382 inhibits breast cancer progression and metastasis by affecting the M2 polarization of tumor‑associated macrophages by targeting PGC‑1α.

Macrophages are principal immune cells with a high plasticity in the human body that can differentiate under different conditions in the tumor microenvironment to adopt two polarized phenotypes with opposite functions. Therefore, converting macrophages from the immunosuppressive phenotype (M2) to the inflammatory phenotype (M1) is considered a promising therapeutic strategy for cancer. However, the molecular mechanisms underlying this conversion process have not yet been completely elucidated. In recent years, microRNAs (miRNAs or miRs) have been shown to play key roles in regulating macrophage polarization through their ability to modulate gene expression. In the present study, it was found that miR-382 expression was significantly downregulated in tumor-associated macrophages (TAMs) and M2-polarized macrophages in breast cancer. In vitro, macrophage polarization toward the M2 phenotype and M2-type cytokine release were inhibited by transfection with miR-382-overexpressing lentivirus. Similarly, the overexpression of miR-382 inhibited the ability of TAMs to promote the malignant behaviors of breast cancer cells. In addition, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) was identified as the downstream target of miR-382 and it was found that PGC-1α affected macrophage polarization by altering the metabolic status. The ectopic expression of PGC-1α restored the phenotype and cytokine secretion of miR-382-overexpressing macrophages. Furthermore, PGC-1α expression reversed the miR-382-induced changes in the metabolic state of TAMs and the effects of TAMs on breast cancer cells. Of note, the in vivo growth and metastasis of 4T1 cells were inhibited by miR-382-overexpressing TAMs. Taken together, the results of the present study suggest that miR-382 may alter the metabolic status of macrophages by targeting PGC-1α, thereby decreasing the proportion of TAMs with the M2 phenotype, and inhibiting the progression and metastasis of breast cancer.

GASP1 enhances malignant phenotypes of breast cancer cells and decreases their response to paclitaxel by forming a vicious cycle with IGF1/IGF1R signaling pathway

There is a potential correlation between G-protein-coupled receptor-associated sorting protein 1 (GASP1) and breast tumorigenesis. However, its biological function and underlying molecular mechanism in breast cancer have not been clearly delineated. Here, we demonstrated that GASP1 was highly expressed in breast cancers, and patients harboring altered GASP1 showed a worse prognosis than those with wild-type GASP1. Functional studies showed that GASP1 knockout significantly suppressed malignant properties of breast cancer cells, such as inhibition of cell proliferation, colony formation, migration, invasion and xenograft tumor growth in nude mice as well as induction of G1-phase cell cycle arrest, and vice versa. Mechanistically, GASP1 inhibited proteasomal degradation of insulin-like growth factor 1 receptor (IGF1R) by competitively binding to IGF1R with ubiquitin E3 ligase MDM2, thereby activating its downstream signaling pathways such as NF-κB, PI3K/AKT, and MAPK/ERK pathways given their critical roles in breast tumorigenesis and progression. IGF1, in turn, stimulated GASP1 expression by activating the PI3K/AKT pathway, forming a vicious cycle propelling the malignant progression of breast cancer. Besides, we found that GASP1 knockout obviously improved the response of breast cancer cells to paclitaxel. Collectively, this study demonstrates that GASP1 enhances malignant behaviors of breast cancer cells and decreases their cellular response to paclitaxel by interacting with and stabilizing IGF1R, and suggests that it may serve as a valuable prognostic factor and potential therapeutic target in breast cancer.

Intermedin (adrenomedullin 2) promotes breast cancer metastasis via Src/c-Myc-mediated ribosome production and protein translation.

Breast cancer is the most frequently diagnosed cancer and is the leading cause of cancer-associated mortality in women worldwide. Intermedin (IMD, also known as Adrenomedullin 2, ADM2) is an endogenous peptide that belongs to the calcitonin gene-related peptide family and has been reported to play important roles in several types of cancers, including breast cancer. In this study, we sought to investigate how IMD affects the behavior of breast cancer cells, the underlying mechanism of these effects, and whether blockade of IMD has a therapeutic effect against breast cancer. Transcriptome sequencing (RNA-Seq), cell biological experiments, Western blotting, immunoprecipitation, and animal tumor models were used. IMD expression was significantly increased in breast cancer samples, and the IMD level was positively correlated with lymph node metastasis and Ki67 expression. Cell biological experiments showed that IMD promoted the anchorage-independent growth, migration, and invasive ability of breast cancer cells. Inhibiting IMD activity with an anti-IMD monoclonal antibody blocked these tumor-promoting effects. In addition, blockade of IMD reduced in situ tumor growth and significantly decreased lung metastasis of 4T1 breast cancer in vivo. IMD induced Src kinase phosphorylation, which triggered the transcription of c-Myc, a major oncoprotein controlling the expression of genes that encode ribosomal components. Our data suggest that IMD is involved in breast cancer cell invasion and metastasis, potentially through increasing ribosome biogenesis and protein translation via the Src/c-Myc signaling pathway. These results suggest that IMD may be a novel target for the treatment of breast cancer.