Phenotype Of Breast Cancer Cells Research Articles

Heterozygous Knockout of ARID4B Using CRISPR/Cas9 Attenuates Some Aggressive Phenotypes in a Breast Cancer Cell Line.

Breast cancer is one of the leading causes of death in women around the world. Over time, many genes and mutations that are associated with the development of this disease have been identified. However, the specific role of many genes has not yet been fully elucidated. Higher ARID4B expression has been identified as a risk factor for diverse cancer types. Silencing experiments also showed that ARID4B is associated with developing cancer-associated characteristics. However, no transcriptomic studies have shown the overall cellular effect of loss of function in breast cancer in humans. This study addresses the impact of loss-of-function mutations in breast cancer MCF-7 cells. Using the CRISPR/Cas9 system, we generated mutations that caused heterozygous truncated proteins, isolating three monoclonal lines carrying insertions and deletions in ARID4B. We observed reduced proliferation and migration in in vitro experiments. In addition, from RNA-seq assays, a differential expression analysis shows known and novel deregulated cancer-associate pathways in mutated cells supporting the impact of ARID4B. For example, we found the AKT-PI3K pathway to be altered at the transcript level but through different genes than those reported for ARID4B. Our transcriptomic results also suggest new insights into the role of ARID4B in aggressiveness by the epithelial-to-mesenchymal transition and TGF-β pathways and in metabolism through cholesterol and mevalonate pathways. We also performed exome sequencing to show that no off-target effects were apparent. In conclusion, the ARID4B gene is associated with some aggressive phenotypes in breast cancer cells.

Analysis of Interleukin-6 Gene Variants (rs1800795, rs1800796, rs1554606, rs1800797, rs2069840, rs12700386, and rs2069861) as Prognostic Markers in Breast Cancer: A Systematic Review, Meta-Analysis, and Network Analysis.

Interleukin-6 (IL-6) has obviously tumor-promoting and tumor-inhibitory effects and can induce an epithelial-mesenchymal transition phenotype in human breast cancer (BC) cells and implicate its potential to promote BC metastasis. Herein, we aimed to evaluate the association of IL-6 variants (rs1800795, rs1800796, rs1554606, rs1800797, rs2069840, rs12700386, and rs2069861) with the susceptibility to BC. The databases of PubMed/Medline, Web of Science, Scopus, and Cochrane Library were searched until December 19, 2022, without any restrictions. The quality assessment of each study was performed based on the Newcastle-Ottawa Scale tool. The Review Manager 5.3 software presented the effect sizes including odds ratio (OR) along with a 95% confidence interval (CI). Both publication bias and sensitivity analyses were carried out by the Comprehensive Meta-Analysis version 2.0 software. A total of 2,508 records were identified among databases and at last, 27 articles were entered into the meta-analysis. Seven polymorphisms of IL-6 were entered into the analyses. Just rs1800797 polymorphism in the dominant model (OR = 1.51; 95% CI = 1.15-2.00; P = 0.003) and rs2069840 polymorphism in heterozygous (OR = 0.89; 95% CI = 0.81-0.97; P = 0.008) and dominant (OR = 0.91; 95% CI = 0.84-0.99; P = 0.02) models had a significant association with the BC risk. In conclusion, among 7 polymorphisms and despite a few included cases, the present meta-analysis recommended that the AA+GA genotype of rs1800797 polymorphism had a significantly elevated risk and the GC and the CC+GC genotypes of rs2069840 polymorphism had a protective role in the BC patients.

The effect of an exopolysaccharide probiotic molecule from Bacillus subtilis on breast cancer cells

IntroductionMany well-known risk factors for breast cancer are associated with dysbiosis (an aberrant microbiome). However, how bacterial products modulate cancer are poorly understood. In this study, we investigated the effect of an exopolysaccharide (EPS) produced by the commensal bacterium Bacillus subtilis on breast cancer phenotypes. Although B. subtilis is commonly included in probiotic preparations and its EPS protects against inflammatory diseases, it was virtually unknown whether B. subtilis-derived EPS affects cancer.MethodsThis work investigated effects of EPS on phenotypes of breast cancer cells as a cancer model. The phenotypes included proliferation, mammosphere formation, cell migration, and tumor growth in two immune compromised mouse models. RNA sequencing was performed on RNA from four breast cancer cells treated with PBS or EPS. IKKβ or STAT1 signaling was assessed using pharmacologic or RNAi-mediated knock down approaches. ResultsShort-term treatment with EPS inhibited proliferation of certain breast cancer cells (T47D, MDA-MB-468, HCC1428, MDA-MB-453) while having little effect on others (MCF-7, MDA-MB-231, BT549, ZR-75-30). EPS induced G1/G0 cell cycle arrest of T47D cells while increasing apoptosis of MDA-MB-468 cells. EPS also enhanced aggressive phenotypes in T47D cells including cell migration and cancer stem cell survival. Long-term treatment with EPS (months) led to resistance in vitro and promoted tumor growth in immunocompromised mice. RNA-sequence analysis showed that EPS increased expression of pro-inflammatory pathways including STAT1 and NF-κB. IKKβ and/or STAT1 signaling was necessary for EPS to modulate phenotypes of EPS sensitive breast cancer cells. DiscussionThese results demonstrate a multifaceted role for an EPS molecule secreted by the probiotic bacterium B. subtilis on breast cancer cell phenotypes. These results warrant future studies in immune competent mice and different cancer models to fully understand potential benefits and/or side effects of long-term use of probiotics.

Therapeutic influence of simvastatin on MCF-7 and MDA-MB-231 breast cancer cells via mitochondrial depletion and improvement in chemosensitivity of cytotoxic drugs

BackgroundBreast cancer is the most commonly diagnosed cancer worldwide with 2.26 million cases in 2020. Cancer heterogeneity is the major challenge before existing therapeutic modalities due to metabolic variability of the cells as Warburg and anti-Warburg both type of metabolic phenotypes has been reported as a major contributing factors for cancer progression, invasion, metastasis and relapse. Also, this metabolic variability is associated with chemo and radio-resistance and poor therapeutic outcomes. Therefore, in present study we put an attempt to understand how simvastatin exert its effects on two metabolically different cell types and second how this drug can affect mitochondrial biomass, mt-DNA and glycolysis in both the cell types. MethodsWe have observed effects of simvastatin on MCF-7 (dependent more on OXPHOS) and MDA-MB-231 (TNBC; more glycolytic with defected mitochondria) cells alone and after simvastatin pre-treatment followed by cytotoxic drugs including cisplatin, doxorubicin, gemcitabine, vincristine. We have conducted MTT assay for viability, cell death detection assay, apoptotic morphology study, scratch assay, transwell migration assay, lactate estimation in media (glycolysis parameter), mt-DNA to n-DNA ratio, mitotracker red (for mitochondrial membrane potential) and mitotracker green staining (for mitochondrial biomass) and qPCR to study expression of mitochondrial transcription factors and apoptotic genes including PGC-1α, NRF-1, NRF-2, TFAM, Bcl-2 and Bax. ResultsWe observed that 20 μM simvastatin (SIM) was most efficient dose for MCF-7, whereas 12.5 μM for MDA-MB-231 cells. Simvastatin itself caused a significant decrease in viability, increased cell death, and diminished wound closure in scratch assay as well as inhibited transwell migration. Also, the cells pre-treated with simvastatin for 72 h followed by treatment with cytotoxic drugs for 48 h increased chemo-sensitivity of cisplatin (CIS), doxorubicin (DOX), gemcitabine (GEM) and vincristine (VIN). SIM alone and in pre-treatment followed by cytotoxic drug treatment studies, there was a significant decrease in mitochondrial biomass and mitochondrial membrane potential (MMP), but also decreased glycolysis as evidenced by decrease in lactate levels in culture media. For inhibition of migratory potential, it was in the following order: CIS ˃ VIN ˃DOX˃ GEM, which was in the same order to diminish mitochondrial functionality (mt-DNA/n-DNA ratio, mitotracker green staining and a significant decrease in the expression of transcriptional factors of mitochondrial biogenesis). Contrastingly a decrease in the same order was observed in lactate concentration independent to the mitochondrial loss, but probably via inherent ability of the drugs to reduce lactate and glycolysis. However, for cell death, apoptotic phenotype, diminished expression of Bcl-2 along with increase in Bax and loss of viability, the efficiency of simvastatin alone and in pre-treatment studies was in the following order: VIN ˃ DOX˃GEM˃CIS, which was supported by loss of fluorescence of mitotracker red, suggested decrease in MMP; marker of cell death. ConclusionWe conclude that by using different doses simvastatin can target different metabolic phenotypes of breast cancer cells and can also increase the chemo-sensitivity of cytotoxic drugs, so that they can work efficiently at lower doses which will ultimately diminish the cost and toxicity issues.

An Increase in HSF1 Expression Directs Human Mammary Epithelial Cells toward a Mesenchymal Phenotype.

HSF1 is a well-known heat shock protein expression regulator in response to stress. It also regulates processes important for growth, development or tumorigenesis. We studied the HSF1 influence on the phenotype of non-tumorigenic human mammary epithelial (MCF10A and MCF12A) and several triple-negative breast cancer cell lines. MCF10A and MCF12A differ in terms of HSF1 levels, morphology, growth in Matrigel, expression of epithelial (CDH1) and mesenchymal (VIM) markers (MCF10A are epithelial cells; MCF12A resemble mesenchymal cells). HSF1 down-regulation led to a reduced proliferation rate and spheroid formation in Matrigel by MCF10A cells. However, it did not affect MCF12A proliferation but led to CDH1 up-regulation and the formation of better organized spheroids. HSF1 overexpression in MCF10A resulted in reduced CDH1 and increased VIM expression and the acquisition of elongated fibroblast-like morphology. The above-mentioned results suggest that elevated levels of HSF1 may direct mammary epithelial cells toward a mesenchymal phenotype, while a lowering of HSF1 could reverse the mesenchymal phenotype to an epithelial one. Therefore, HSF1 may be involved in the remodeling of mammary gland architecture over the female lifetime. Moreover, HSF1 levels positively correlated with the invasive phenotype of triple-negative breast cancer cells, and their growth was inhibited by the HSF1 inhibitor DTHIB.

Dysregulated Expression of LncRNA-SChLAP1 in Breast Cancer

This study aimed to investigate the expression and clinical significance of the long chain non-coding RNA SCHLAP1 in breast cancer tissues. The research included 60 breast cancer patients treated between June 2017 and September 2019. Cancer and adjacent tissues were collected for analysis. Furthermore, breast cancer cell lines MCF-7 and HCC1937, along with normal breast epithelial cell line MCF10A, were used to study the impact of LncRNA SCHLAP1 on breast cancer cell phenotypes. qRT-PCR was employed to measure LncRNA SCHLAP1 expression levels in cells and tissues. The results demonstrated that LncRNA SCHLAP1 was significantly up-regulated in breast cancer cells and patient tissues (P <0.01). Moreover, differences in LncRNA SCHLAP1 expression were observed in patients with varying age, lymph node invasion, TNM staging, HER-2, and Ki-67 expression levels (P <0.01). Patients with high LncRNA SCHLAP1 expression had a significantly lower two-year survival rate (P <0.01). In vitro experiments revealed that down-regulated LncRNA SCHLAP1 inhibited the proliferation, migration, and invasion of MCF-7 cells, while promoting apoptosis (P <0.01). This study suggests that LncRNA SCHLAP1 is associated with breast cancer progression and patient survival, serving as an independent predictor for breast cancer progression.

Bone-matrix mineralization dampens integrin-mediated mechanosignalling and metastatic progression in breast cancer.

In patients with breast cancer, lower bone mineral density increases the risk of bone metastasis. Although the relationship between bone-matrix mineralization and tumour-cell phenotype in breast cancer is not well understood, mineralization-induced rigidity is thought to drive metastatic progression via increased cell-adhesion forces. Here, by using collagen-based matrices with adjustable intrafibrillar mineralization, we show that, unexpectedly, matrix mineralization dampens integrin-mediated mechanosignalling and induces a less proliferative stem-cell-like phenotype in breast cancer cells. In mice with xenografted decellularized physiological bone matrices seeded with human breast tumour cells, the presence of bone mineral reduced tumour growth and upregulated a gene-expression signature that is associated with longer metastasis-free survival in patients with breast cancer. Our findings suggest that bone-matrix changes in osteogenic niches regulate metastatic progression in breast cancer and that in vitro models of bone metastasis should integrate organic and inorganic matrix components to mimic physiological and pathologic mineralization.

LncRNA TYMSOS facilitates breast cancer metastasis and immune escape through downregulating ULBP3

The focus of the study is to examine the function of TYMSOS in immune escape of breast cancer, which is the most frequently diagnosed malignancy among women globally. Our study demonstrated that upregulated TYMSOS was associated with unfavorable prognosis and immune escape in breast cancer. TYMSOS promoted the malignant phenotypes of breast cancer cells, and reduced the cytotoxicity of NK92 cells on these cells. CBX3 was a downstream effector in TYMSOS-induced malignant phenotypes in breast cancer cells. Mechanistic studies showed that TYMSOS facilitated CBX3-mediated transcriptional repression of ULBP3, and it also promoted SYVN1-mediated ubiquitin-proteasomal degradation of ULBP3. TYMSOS promoted cell growth, metastasis, and immune escape via CBX3/ULBP3 or SYVN1/ULBP3 axis. The invivo studies further showed that silencing of TYMSOS repressed tumor growth and boosted NK cell cytotoxicity. In sum, TYMSOS boosted breast cancer metastasis and immune escape via CBX3/ULBP3 or SYVN1/ULBP3 axis.

Differential miRNA expression of hypoxic MCF7 and PANC-1 cells.

Hypoxia plays a critical role in the tumor microenvironment by affecting cellular proliferation, metabolism, apoptosis, DNA repair, and chemoresistance. Since hypoxia provokes a distinct shift of microRNA, it is important to illustrate the relative contribution of each hypoxamiR to cancer progression. The present study aims to shed light on the hypoxamiRs that are involved in pancreatic and breast cancer progression to highlight novel targets for the development of new therapies. For 20 cycles, MCF7 breast cancer cells and PANC-1 pancreatic cancer cells were subjected to chronic cyclic hypoxia, which consisted of 72 hours of hypoxia followed by 24 hours of reoxygenation. After 10 and 20 cycles of hypoxia, miRNA expression alterations were profiled using RT-PCR array and further analyzed using a visual analytics platform. The MTT cell proliferation assay was used to determine hypoxic cells' chemoresistance to doxorubicin. Under chronic cyclic hypoxia, hypoxic PANC-1 cells have a comparable doubling time with their normoxic counterparts, whereas hypoxic MCF7 cells show a massive increase in doubling time when compared to their normoxic counterparts. Both hypoxic cell lines developed EMT-like phenotypes as well as doxorubicin resistance. According to the findings of miRNet, 6 and 10 miRNAs were shown to play an important role in enriching six hallmarks of pancreatic cancer in the 10th and 20th cycles of hypoxia, respectively, while 7 and 11 miRNAs were shown to play an important role in enriching the four hallmarks of breast cancer in the 10th and 20th cycles of hypoxia, respectively. miR-221, miR-21, miR-155, and miR-34 were found to be involved in the potentiation of hypoxic PANC-1 hallmarks at both the 10th and 20th cycles, while miR-93, miR-20a, miR-15, and miR-17 were found to be involved in the potentiation of hypoxic MCF7 hallmarks at both the 10th and 20th cycles. This variation in miRNA expression was also connected to the emergence of an EMT-like phenotype, alterations in proliferation rates, and doxorubicin resistance. The chemosensitivity results revealed that chronic cyclic hypoxia is critical in the formation of chemoresistant phenotypes in pancreatic and breast cancer cells. miR-181a and let-7e expression disparities in PANC1, as well as miR-93, miR-34, and miR-27 expression disparities in MCF7, may be associated with the formation of chemoresistant MCF7 and PANC-1 cells following 20 cycles of chronic cyclic hypoxia. Indeed, further research is needed since the particular mechanisms that govern these processes are unknown.

Targeting SHP2 with an Active Site Inhibitor Blocks Signaling and Breast Cancer Cell Phenotypes.

The Src homology phosphotyrosyl phosphatase 2 (SHP2) is an oncogenic protein for which targeted therapies are being sought. In line with this idea, we have previously reported the development of a specific active site inhibitor named CNBDA that showed effectivity in suppressing the transformation phenotypes of breast cancer cells. To improve efficacy, we introduced limited modifications to the parent compound and tested potency in vitro and under cell culture conditions. Of these modifications, removal of one of the butyric acid groups led to the production of a compound named CNBCA, which showed a 5.7-fold better potency against the SHP2 enzyme activity in vitro. In addition, CNBCA showed better selectivity to SHP2 than the control PTPs (SHP1 and PTP1B) as determined by the phosphatase assay. Furthermore, CNBCA binds and inhibits enzyme activity of full-length SHP2 in cellular contexts, downregulates SHP2 mediated signaling, and suppresses breast cancer cell phenotypes, including cell proliferation, colony formation, and mammosphere growth. These findings show that targeting SHP2 with CNBCA is effective against the cancerous properties of breast cancer cells.

Overexpression of Long Non-coding RNA uc.246 Facilitates Angiogenesis, Migration, and EMT Phenotype of Human Breast Cancer Cells.

Breast cancer is the most malignant subtype of gynecological tumors and with aggressive biological behavior and poor outcome. Ultra-conserved non-coding RNA (ucRNA) is a newly discovered class of long non-coding RNAs (lncRNAs) which involved in the regulation of interaction network of genes. However, the exact function and mechanism by which ucRNA modulates breast cancer aggressive has not yet to be completely elucidated. In the present study, we demonstrated that the expression of uc.246 was significantly upregulated in metastatic breast cancer patients and TNBC cell lines, compared with those in controls. Furthermore, overexpression of uc.246 in MCF-7 cell lines enhanced the capacity of breast cancer cells to induce tube formation and migration of HUVECs, and, finally, enhanced breast cancer cells metastasis. Meanwhile, uc.246 overexpressing enhances the EMT phenotype of TNBC cells. Mechanistically, we found that uc.246 promoted malignant progression of breast cancer via upregulating the levels of VEGF-C and increased the levels of mesenchymal marker protein. Our results demonstrated that uc.246 induced angiogenesis, migration, and EMT phenotype and may represent a novel prognostic biomarker and therapeutic target for patients with breast cancer.

The Synergistic Effect of Proanthocyanidin and HDAC Inhibitor Inhibit Breast Cancer Cell Growth and Promote Apoptosis.

Histone deacetylase inhibitor (HDACi) is a drug mainly used to treat hematological tumors and breast cancer, but its inhibitory effect on breast cancer falls short of expectations. Grape seed proanthocyanidin extract (GSPE) with abundant proanthocyanidins (PAs) has been explored for its inhibition of HDAC activity in vitro and in vivo. To enhance HDACi's effectiveness, we investigated the potential of PA to synergistically enhance HDACi chidamide (Chi), and determined the underlying mechanism. We evaluated the half-inhibitory concentration (IC50) of PA and Chi using the cell counting kit 8 (CCK8), and analyzed drugs' synergistic effect with fixed-ratio combination using the software Compusyn. Breast cancer cell's phenotypes, including short-term and long-term proliferation, migration, invasion, apoptosis, and reactive oxygen species (ROS) levels, were assessed via CCK8, clone-formation assay, wound-healing test, Transwell Matrigel invasion assay, and flow-cytometry. Protein-protein interaction analysis (PPI) and KEGG pathway analysis were used to determine the underlying mechanism of synergy. PA + Chi synergistically inhibited cell growth in T47D and MDA-MB-231 breast cancer cell lines. Short-term and long-term proliferation were significantly inhibited, while cell apoptosis was promoted. Ten signaling pathways were identified to account for the synergistic effect after RNA sequencing. Their synergism may be closely related to the steroid biosynthesis and extracellular matrix (ECM) receptor interaction pathways. PA + Chi can synergistically inhibit breast cancer cell growth and proliferation, and promote apoptosis. These effects may be related to steroid biosynthesis or the ECM receptor pathway.

IGF-1 Stimulates Glycolytic ATP Production in MCF-7L Cells.

The Insulin-like Growth Factor (IGF) system in breast cancer progression has been a matter of interest for decades, but targeting this system did not result in a successful clinical strategy. The system's complexity and homology of its two receptors-insulin receptor (IR) and type 1 insulin-like growth factor receptor (IGF-1R)-are possible causes. The IGF system maintains cell proliferation and also regulates metabolism, making it a pathway to explore. To understand the metabolic phenotype of breast cancer cells, we quantified their real-time ATP production rate upon acute stimulation with ligands-insulin-like growth factor 1 (1GF-1) and insulin. MCF-7L cells express both IGF-1R and IR, while tamoxifen-resistant MCF-7L (MCF-7L TamR) cells have downregulated IGF-1R with unchanged IR levels. Treating MCF-7L cells with 5 nM IGF-1 increased the glycolytic ATP production rate, while 10 nM insulin did not affect metabolism when compared with the control. Neither treatment altered ATP production in MCF-7L TamR cells. This study provides evidence of the relationship between metabolic dysfunction, cancer, and the IGF axis. In these cells, IGF-1R, and not IR, regulates ATP production.

Targeting long non-coding RNA MALAT1 reverses cancerous phenotypes of breast cancer cells through microRNA-561-3p/TOP2A axis

Non-coding RNAs, including Inc-RNA and miRNA, have been reported to regulate gene expression and are associated with cancer progression. MicroRNA-561-3p (miR-561-3p), as a tumor suppressor, has been reported to play a role in preventing cancer cell progression, and MALAT1 (Lnc-RNA) have also been demonstrated to promote malignancy in various cancers, such as breast cancer (BC). In this study, we aimed to determine the correlation between miR-561-3p and MALAT1 and their roles in breast cancer progression. The expression of MALAT1, mir-561-3p, and topoisomerase alpha 2 (TOP2A) as a target of miR-561-3p was determined in BC clinical samples and cell lines via qRT-PCR. The binding site between MALAT1, miR-561-3p, and TOP2A was investigated by performing the dual luciferase reporter assay. MALAT1 was knocked down by siRNA, and cell proliferation, apoptotic assays, and cell cycle arrest were evaluated. MALAT1 and TOP2A were significantly upregulated, while mir-561-3p expression was downregulated in BC samples and cell lines. MALAT1 knockdown significantly increased miR-561-3p expression, which was meaningfully inverted by co-transfection with the miR 561-3p inhibitor. Furthermore, the knockdown of MALAT1 by siRNA inhibited proliferation, induced apoptosis, and arrested the cell cycle at the G1 phase in BC cells. Notably, the mechanistic investigation revealed that MALAT1 predominantly acted as a competing endogenous RNA in BC by regulating the miR-561-3p/TOP2A axis. Based on our results, MALAT1 upregulation in BC may function as a tumor promoter in BC via directly sponging miRNA 561-3p, and MALAT1 knockdown serves a vital antitumor role in BC cell progression through the miR-561-3p/TOP2A axis.

Collagen-induced DDR1 upregulates CXCL5 to promote neutrophil extracellular traps formation and Treg infiltration in breast cancer

Neutrophil extracellular traps (NETs) have been implicated in many cancers, but the regulatory mechanisms in the context of breast cancer have not been thoroughly discussed. This study proposed a mechanism based on collagen-activated DDR1/CXCL5 for NET formation in breast cancer. Through TCGA and GEO-based bioinformatics analysis, we examined the DDR1 expression and the correlation of CXCL5 with immune cell infiltration in breast cancer. It was found that high DDR1 expression was correlated with poor prognosis of patients with breast cancer, and CXCL5 was positively correlated with neutrophil and Treg infiltration. Expression of DDR1 and CXCL5 was determined in collagen-treated breast cancer cells, the malignant phenotypes of which were evaluated by ectopic expression and knockdown methods. Collagen-activated DDR1 upregulated CXCL5 expression, resulting in augmented malignant phenotypes of breast cancer cells in vitro. The formation of NETs caused promotion in the differentiation and immune infiltration of Tregs in breast cancer. A in situ breast cancer mouse model was constructed, where NET formation and lung metastasis of breast cancer cells were observed. The differentiation of CD4+ T cells isolated from the mouse model was induced into Tregs, followed by Treg infiltration assessment. It was further confirmed in vivo that DDR1/CXCL5 induced the formation of NETs to promote immune infiltration of Tregs, driving tumor growth and metastasis. Accordingly, our results provided new mechanistic insights for an understanding of the role of collagen-mediated DDR1/CXCL5 in formation of NETs and Treg infiltration, revealing potential targets for therapeutic intervention of breast cancer.

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.

Oncogenic roles of GPR176 in breast cancer: a potential marker of aggressiveness and a potential target of gene therapy.

Belonging to the G-protein coupled receptor 1 family, G protein-coupled receptor 176 (GPR176) is associated with the Gz/Gx G-protein subclass and is capable of decreasing cAMP production. GPR176 expression was detected by qRT-PCR, bioinformatics analysis, Western blot and immunohistochemistry, and compared with clinicopathological characteristics of breast cancer. GPR176-related genes and pathways were subjected to bioinformatic analysis. We also explored the effects of GPR176 on the phenotypes of breast cancer cells. Lower expression of GPR176 mRNA was seen in breast cancer than in normal tissues, but the opposite pattern was found for its protein (p < 0.05). GPR176 mRNA was associated with female sex, low T staging, non-Her-2+ subtypes, non-mutant p53 status in breast cancer (p < 0.05). GPR176 methylation was negatively correlated with its mRNA level and T staging in breast cancer, and was higher in breastcancer than normal tissues (p < 0.05). GPR176 protein expression was positively correlated with older age, small tumor size, and non-luminal-B subtype of breast cancers (p < 0.05). The differential genes of GPR176 were involved in receptor-ligand interaction, RNA maturation, and so forth (p < 0.05). GPR176-related genes were categorized into cell mobility, membrane structure, and so on (p < 0.05). GPR176 knockdown weakened the proliferation, glucose catabolism, anti-apoptosis, anti-pyroptosis, migration, invasion, and epithelial-mesenchymal transition of breast cancer cells. These results indicate that GPR176 might be involved in the tumorigenesis and subsequent progression of breast cancer by deteriorating aggressive phenotypes. It might be utilized as a potential biomarker to indicate the aggressive behaviors and poor prognosis of breast cancer and a potential target of genetic therapy.

Kruppel-like factor 8 regulates triple negative breast cancer stem cell-like activity.

Breast tumor development is regulated by a sub-population of breast cancer cells, termed cancer stem-like cells (CSC), which are capable of self-renewing and differentiating, and are involved in promoting breast cancer invasion, metastasis, drug resistance and relapse. CSCs are highly adaptable, capable of reprogramming their own metabolism and signaling activity in response to stimuli within the tumor microenvironment. Recently, the nutrient sensor O-GlcNAc transferase (OGT) and O-GlcNAcylation was shown to be enriched in CSC populations, where it promotes the stemness and tumorigenesis of breast cancer cells in vitro and in vivo. This enrichment was associated with upregulation of the transcription factor Kruppel-like-factor 8 (KLF8) suggesting a potential role of KLF8 in regulating CSCs properties. Triple-negative breast cancer cells were genetically modified to generate KLF8 overexpressing or KLF8 knock-down cells. Cancer cells, control or with altered KLF8 expression were analyzed to assess mammosphere formation efficiency, CSCs frequency and expression of CSCs factors. Tumor growth in vivo of control or KLF8 knock-down cells was assessed by fat-pad injection of these cell in immunocompromised mice. Here, we show that KLF8 is required and sufficient for regulating CSC phenotypes and regulating transcription factors SOX2, NANOG, OCT4 and c-MYC. KLF8 levels are associated with chemoresistance in triple negative breast cancer patients and overexpression in breast cancer cells increased paclitaxel resistance. KLF8 and OGT co-regulate each other to form a feed-forward loop to promote CSCs phenotype and mammosphere formation of breast cancer cells. These results suggest a critical role of KLF8 and OGT in promoting CSCs and cancer progression, that may serve as potential targets for developing strategy to target CSCs specifically.

CSF2 upregulates CXCL3 expression in adipocytes to promote metastasis of breast cancer via the FAK signaling pathway.

Recent studies have demonstrated that cancer-associated adipocytes (CAAs) in the tumor microenvironment are involved in the malignant progression of breast cancer. However, the underlying mechanism of CAA formation and its effects on the development of breast cancer are still unknown. Here, we show that CSF2 is highly expressed in both CAAs and breast cancer cells. CSF2 promotes inflammatory phenotypic changes of adipocytes through the Stat3 signaling pathway, leading to the secretion of multiple cytokines and proteases, particularly C-X-C motif chemokine ligand 3 (CXCL3). Adipocyte-derived CXCL3 binds to its specific receptor CXCR2 on breast cancer cells and activates the FAK pathway, enhancing the mesenchymal phenotype, migration, and invasion of breast cancer cells. In addition, a combination treatment targeting CSF2 and CXCR2 shows a synergistic inhibitory effect on adipocyte-induced lung metastasis of mouse 4T1 cells in vivo. These findings elucidate a novel mechanism of breast cancer metastasis and provide a potential therapeutic strategy for breast cancer metastasis.

Abstract 6022: The importance of DNA methylation to breast cancer cell phenotype and its role in the anticancer activity of withaferin-A

Abstract Breast Cancer (BC) is a widespread malignancy that affects the lives of millions of women each year. Prevention of BC through administration of epigenetically active dietary phytochemicals has received increased interest in recent years due to its relatively low cost, few side effects and potential to reduce the financial and healthcare burdens associated with BC. Many phytochemicals’ anticancer functions are thought to arise from their effects on the epigenome, although the relative importance of specific genes’ epigenetic states remain unclear. To elucidate this, we utilized human BC cell lines in combination with CRISPR-dCas technology tied to methylation modifiers to explore the importance of gene specific DNA methylation to cancer cell phenotype in both naïve BC cells and BC cells treated with the phytochemical Withaferin A (WA). We found that demethylation of promoters of the tumor suppressors p21 and p53 results in increased gene expression, while methylation of the promoter of the oncogene CCND1 results in decreased in gene expression. Additionally, changes to biological processes were associated with tumor suppressor promoter methylation state, including increases in cell cycle arrest for a demethylated p21 promoter and decreases in cell viability for a demethylated p53 promoter. We also found that downregulation of p21 through targeting DNMT3A to its promoter was able to ablate the anticancer function of WA in both MDA-MB-231 and MCF-7 cells. Taken together, these results highlight the potential importance of DNA methylation changes for cancer cell phenotype and a possible mechanism of action for the phytochemical WA in BC prevention. Citation Format: Andrew Brane, Trygve O. Tollefsbol. The importance of DNA methylation to breast cancer cell phenotype and its role in the anticancer activity of withaferin-A [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6022.