Expression In MCF-7 Research Articles

The effect of hesperidin and luteolin isolated from Eriocephalus africanus on apoptosis, cell cycle and miRNA expression in MCF-7

This study investigates the molecular mechanisms underlying the anticancer activity of hesperidin and luteolin, isolated from Eriocephalus africanus, in the human breast carcinoma cell line (MCF-7). The viability of MCF-7 cells, upon treatment with hesperidin and luteolin, was evaluated using the 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay; apoptotic activity and effect on cell cycle progression were analysed by flow cytometry; effect on expression of key apoptotic regulatory genes (caspase-3, -8, -9, Bcl-2 and Bax) and apoptotic microRNAs (-16, -21 and -34a) were evaluated using quantitative real-time PCR. Hesperidin and luteolin reduced cell viability in a dose and time-dependent manner, caused a significant accumulation of apoptotic cells into the G0/G1 and sub-G1 cell cycle phases, induced apoptosis through the intrinsic and extrinsic pathways, down-regulated anti-apoptotic, Bcl-2, and upregulated pro-apoptotic, Bax. In addition, hesperidin and luteolin significantly downregulated the expression of miR-21 and upregulated that of miR-16 and -34a in MCF-7. Spearman`s rank analysis revealed a positive correlation between Bcl-2 and miR-21 and negative correlation between Bcl-2, miR-16 and -34a. Findings from this study provide new evidence on the molecular basis of the anticancer activity of luteolin and hesperidin in breast cancer cell lines. Communicated by Ramaswamy H. Sarma

Effect of MicroRNA-766 Promotes Proliferation, Chemoresistance, Migration, and Invasion of Breast Cancer Cells

IntroductionBreast cancer (BCa) remains the most common cancer in women worldwide. It has been shown that microRNAs (miRs) play essential roles in tumorigenesis and progression in many types of cancers, including BCa. We assessed the role of miR-766 on the proliferation, chemosensitivity, migration, and invasion of BCa cells. Materials and MethodsThe effect of miR-766 on the proliferation of MCF-7 and T47D BCa cells was evaluated using the MTT assay. The function of miR-766 on the migration and invasion of MCF-7 and T47D cells was examined using Transwell migration and Matrigel invasion assays. Protein expression was evaluated by Western blot. The role of miR-766 on 5-fluorouracil–induced apoptosis in MCF-7 and T47D cells was determined using the Caspase-Glo3/7 assay. A subcutaneous tumor xenograft was performed to examine the effect of miR-766 on tumor growth in vivo. ResultsUpregulation of miR-766 improved the proliferation, invasion, and migration of BCa cells. Furthermore, miR-766 reduced the sensitivity of MCF-7 and T47D cells to 5-fluorouracil treatment. The tumor xenograft experiment showed that miR-766 promoted BCa growth in vivo. miR-766 decreased 5-flurouracil–induced apoptosis by regulation of BAX and Bcl-2 expression. miR-766 also affected the epithelial–mesenchymal transition by altering E-cadherin, N-cadherin, SNAIL, and vimentin expression in MCF-7 and T47D cells. Further study showed that the expression of phosphatase and tensin homolog and phosphorylated AKT in MCF-7 and T47D cells had changed after aberrant expression of miR-766.Conclusion: miR-766 displayed important roles in tumorigenesis and progression in BCa cells and might act as a potential biomarker to predict the chemotherapy response and progression in BCa.

Antiviral Activity of Compound L3 against Dengue and Zika Viruses In Vitro and In Vivo.

Dengue virus (DENV) and Zika virus (ZIKV) are mosquito-borne flaviviruses that cause severe illness after infection. Currently, there are no specific or effective treatments against DENV and ZIKV. Previous studies have shown that tyrosine kinase activities and signal transduction are involved in flavivirus replication, suggesting a potential therapeutic strategy for DENV and ZIKV. In this study, we found that compound L3 can significantly reduce viral protein expression and viral titers in HEK-293, MCF-7, HepG2, and Huh-7 cells and exhibits superior therapeutic efficacy against flaviviral infection compared to other tyrosine kinase inhibitors. In addition, compound L3 can decrease endogenous HER2 activation and inhibit the phosphorylation of the HER2 downstream signaling molecules Src and ERK1/2, the levels of which have been associated with viral protein expression in MCF-7 cells. Moreover, silencing HER2 diminished DENV-2 and ZIKV expression in MCF-7 cells, which suggests that HER2 activity is involved in flavivirus replication. Furthermore, in DENV-2-infected AG129 mice, treatment with compound L3 increased the survival rates and reduced the viremia levels. Overall, compound L3 demonstrates therapeutic efficacy both in vitro and in vivo and could be developed as a promising antiviral drug against emerging flaviviruses or for concurrent DENV and ZIKV outbreaks.

Silencing of Growth Differentiation Factor-15 Promotes Breast Cancer Cell Invasion by Down-regulating Focal Adhesion Genes.

As metastasis accounts for most breast cancer (BC)-related deaths, identifying key players becomes research priority. Growth differentiation factor-15 (GDF15), a member of the transforming growth factor-β superfamily, is affected by the actin cytoskeleton and has been associated with cancer. However, its exact role in BC cell invasiveness is vague. GDF15 short-hairpin (shRNA)-mediated silencing was used to inhibit GDF15 expression in MCF-7 and MDA-MB-231 BC cells and gene expression of relevant focal adhesion (FA) genes, cell migration, invasion and tumor spheroid invasion were subsequently analyzed. GDF15 silencing promoted cell migration, cell invasion as well as tumor spheroid invasion and up-regulated urokinase plasminogen activator (uPA) and FA genes, integrin-linked kinase (ILK), LIM zinc finger domain containing 1 (LIMS1), α-parvin (PARVA), and RAS suppressor-1 (RSU1). Computational analysis of Cancer Genome Atlas BC dataset however, revealed no significant correlation between GDF15 expression and metastasis pointing towards a more complex molecular interplay between GDF15, actin cytoskeleton and FA-related genes which ultimately affects their expression pattern, in vivo. GDF15 suppresses BC cell invasion in vitro through down-regulation of FA genes but its role in BC is more complicated in vivo and warrants further investigation.

Estradiol-Induced MMP-9 Expression via PELP1-Mediated Membrane-Initiated Signaling in ERα-Positive Breast Cancer Cells.

Proline-, glutamic acid-, leucine-rich protein 1 (PELP1) is a novel estrogen receptor (ER) coregulator, demonstrated distinctive characters from other ERα coregulators, and has been suggested to be involved in metastasis of several cancers. In ERα-positive breast cancer, PELP1 overexpression enhanced ruffles and filopodium-like structure stimulated by estradiol (E2) through extranuclear cell signaling transduction hereby increased cell motility. However, whether PELP1 is also involved in extracellular matrix remodeling of ERα-positive breast cancer cells is still unknown. In this study, we investigated the role of PELP1 in E2-induced MMP-9 expression and the underlined mechanism. The results demonstrated the following: E2-induced ERα-positive MCF-7 breast cancer cell MMP-9 mRNA and protein expression in a rapid response and concentration-dependent manner. Knocked down PELP1 significantly suppressed E2-induced MMP-9 expression. E2-bovine serum albumin (BSA), a large molecular membrane-impenetrable conjugate of E2, can also upregulate MMP-9 protein expression in MCF-7, and the action of E2-BSA can be abolished by PI3K inhibitor LY294002; treating MCF-7 simultaneously with PELP1-shRNA and LY294002 did not show synergetic inhibitory effect on E2-BSA-induced MMP-9 expression. Our results indicated that estrogen-induced MMP-9 expression in ER-positive breast cancer cells may be through PELP1-mediated PI3K/Akt signaling pathway.

Phototoxic effectiveness of zinc phthalocyanine tetrasulfonic acid on MCF-7 cells with overexpressed P-glycoprotein

The development of multidrug resistance is often associated with the over-expression of P-glycoprotein (P-gp). This protein prevents drug accumulation and extrudes them out of the cell before they reach the intended target. The aim of this study was to develop an in vitro MCF-7 cell line with increased expression of P-gp and test the phototoxicity of a novel photoactivated zinc phthalocyanine tetrasulfonic acid (ZnPcS4) on these cells. The over-expressed P-gp MCF-7 cells (MCF-7/DOX) were developed from wildtype (WT) MCF-7 cells by a stepwise continuous exposure of the WT cells to different concentrations of Doxorubicin (DOX) (0.1 – 1 μM) over a period of 4 months. The P-gp expression was measured using flow cytometry, immunofluorescence and enzyme immunoassay. To verify whether zinc phthalocyanine-mediated photodynamic therapy (ZnPcS4 – PDT) is effective in MCF-7/DOX, we studied the subcellular localization, phototoxicity and nuclear damage. The flow cytometry result showed two distinct peaks of P-gp positive and negative expression in MCF-7/DOX cell population, which correlates with the ELISA-based assay (p˂0.001). The ME16C (Normal breast cells) was used as control. The localization studies showed that ZnPcS4 have greater affinity for lysosome than mitochondria. Phototoxicity results indicated that photoactivated zinc phthalocyanine decreased the cell proliferation and viability as the drug and laser light dosages increased to 16 μM and 20 J/cm2 respectively. PDT-induced cytotoxicity using lactose dehydrogenase (LDH) enzyme leakage as measure did not increase likewise. The ZnPcS4-induced PDT was less effective for MCF-7/DOX cells which could be attributed to decreased retention of ZnPcS4 in major cellular organelles due to the presence of increased drug efflux P-gp. The current findings suggest that, increased P-gp expression, a characteristic of multidrug resistance together with other related intrinsic mechanisms might contribute to render MCF-7/DOX cells less sensitive to ZnPcS4-induced phototoxicity.

ERα36 as a Potential Therapeutic Target for Tamoxifen-Resistant Breast Cancer Cell Line Through EGFR/ERK Signaling Pathway.

BackgroundAcquired tamoxifen resistance is one of the major barriers to the successful treatment of breast cancer. Recently, overexpression of ERα36 was demonstrated to be a potential mechanism for the generation of acquired tamoxifen resistance. This study aims to evaluate the possibility of ERα36 being a therapeutic target for tamoxifen-resistant breast cancer.MethodsA tamoxifen-resistant cell subline (MCF-7/TAM) was established by culturing MCF-7 cells in medium plus 1 μM tamoxifen over 6 months. Colony-forming assay was used to determine the sensitivity of MCF-7/TAM cells to tamoxifen. Stable transfection was used to knockdown ERα36 expression in MCF-7/TAM cells. MTT assay and Transwell migration assay were used to assess the in vitro proliferation and migration, respectively. Nude mouse tumorigenicity assay was used to evaluate in vivo tumorigenicity. Western blot analysis and quantitative real-time PCR (qRT-PCR) were used to examine the expression of ERα36, ERα, EGFR and phosphorylated ERK1/2. The dual-luciferase reporter assay was used to determine the effect of ERα36 on the activity of EGFR-promotor.ResultsMCF-7/TAM cells possessed greatly increased ERα36 expression and EGFR expression and exhibited significantly increased in vitro proliferation and migration ability, as well as increased in vivo tumor growth ability, compared to parental MCF-7 cells. Knockdown of ERα36 expression inhibited in vitro proliferation and migration, as well as in vivo tumor growth ability of MCF-7/TAM cells. ERα36 regulated EGFR expression at the transcriptional level, and knockdown of ERα36 in MCF-7/TAM cells downregulated EGFR expression and then blocked EGFR/ERK signaling pathway.ConclusionKnockdown of ERα36 inhibits the growth of MCF-7/TAM cells in vitro and in vivo by blocking EGFR/ERK signaling pathway. ERα36 may be a candidate therapeutic target for the treatment of tamoxifen-resistant breast cancer.

Precise ratiometric co-loading, co-delivery and intracellular co-release of paclitaxel and curcumin by aid of their conjugation to the same gold nanorods to exert synergistic effects on MCF-7/ADR cells

It is necessary for effective combinational effects that multiple chemotherapeutic agents enter and act on the same tumor cells simultaneously at a suitable ratio. Due to their individual physicochemical or biopharmaceutical properties, they cannot reach the same cells at its predetermined ratio after co-administration. Herein, we report a novel system with precise ratiometric co-loading, co-delivery and intracellular co-release of paclitaxel (PTX) and curcumin (CUR), to investigate their synergistic effects. We prepared the system by conjugating PTX and CUR at different ratios onto the same gold nanorods (GNRs). We demonstrated that PTX and CUR could be precisely ratiometric co-loaded to form dual-drug conjugated biotin-PEG modified GNRs (abbreviated as PTX/CUR@BPGNRs), which could co-deliver dual drugs into tumor cells with a predetermined ratio and co-release them intracellularly. The PTX/CUR@BPGNRs with the mass ratio of PTX and CUR at 1:1 exhibited the best synergistic effect on multidrug resistant MCF-7/ADR cells while the free PTX and CUR mixture with the mass ratio of at 1:0.75 displayed the strongest synergism. Cytotoxicity studies showed that PTX/CUR@BPGNRs are superior to free drug mixture. Furthermore, PTX/CUR@BPGNRs could remarkably induce apoptosis of MCF-7/ADR cells under near-infrared irradiation. Moreover, we found that PTX/CUR@BPGNRs significantly inhibited P-glycoprotein (P-gp) expression in MCF-7/ADR cells.

Inhibition of aldehyde dehydrogenase-1 and p-glycoprotein-mediated multidrug resistance by curcumin and vitamin D3 increases sensitivity to paclitaxel in breast cancer

Treatment of breast cancer by paclitaxel (PAX) often encounters therapeutic failure most likely caused by innate/acquired resistance. Cancer stem cells (CSCs) and multidrug resistance complex (MDR-1 or P-glycoprotein) overexpression are main mechanisms implicated in chemoresistance. Increased aldehyde dehrogenase-1 (ALDH-1) was previously correlated with the stemness features of CSCs and hence is used as a marker for identification and CSCs targeting. The present study, therefore, aimed at investigating the effect of both curcumin (CUR) and vitamin D3 (D3) on MDR-1 and ALDH-1 expression and consequently the resistance to PAX both in vitro and in vivo. CUR was isolated from Turmeric rhizomes and identified using UPLC-ESI-MS/MS. For in vitro studies, the antiproliferative effect of PAX, CUR, 1,25(OH)2D3 (the active form of D3, also known as calcitriol) was determined, each alone and combined (PAX+CUR, PAX+1,25(OH)2D3, and PAX+CUR+1,25(OH)2D3) on MCF-7 breast cancer cells. Ehrlich ascites carcinoma solid tumor animal model was also used for in vivo studies. Combining CUR and/or 1,25(OH)2D3 to PAX showed synergistic cytotoxic interaction on MCF-7 cells. The apoptotic potential was also enhanced, as evidenced by a significant increase in caspase-7 and -9 as well as the pro-apoptotic Bax whereas a decrease in Bcl-2 levels was reported. Combining CUR and 1,25(OH)2D3 to PAX caused a downregulation in both MDR-1 and ALDH-1 gene expression in MCF-7 besides a decrease in their protein levels. In vivo, the triple therapy group (PAX+CUR+D3) showed the least tumor size. It also showed the lowest levels of MDR-1 and ALDH-1. PAX alone, however, showed increased levels of MDR-1 and ALDH-1 compared to control. Overall, the present study showed that PAX, as a monotherapy, demonstrated acquired resistance possibly by increasing MDR-1 expression and enriching CSCs population, as evidenced by increased ALDH-1. However, using CUR and D3 enhanced tumor response to PAX.

Effect of hypoxia on human equilibrative nucleoside transporters hENT1 and hENT2 in breast cancer.

Elevated proliferation rates in cancer can be visualized with positron emission tomography (PET) using 3'-deoxy-3'-l-[18F]fluorothymidine ([18F]FLT). This study investigates whether [18F]FLT transport proteins are regulated through hypoxia. Expression and function of human equilibrative nucleoside transporter (hENT)-1, hENT2, and thymidine kinase 1 (TK1) were studied under normoxic and hypoxic conditions, and assessed with [18F]FLT-PET in estrogen receptor positive (ER+)-MCF7, triple-negative MDA-MB231 breast cancer (BC) cells, and MCF10A cells (human mammary epithelial cells). Functional involvement of hENT2 [18F]FLT transport was demonstrated in all cell lines. In vitro [18F]FLT uptake was higher in MDA-MB231 than in MCF7: 242 ± 9 vs. 147 ± 18% radioactivity/mg protein after 60 min under normoxia. Hypoxia showed no significant change in radiotracer uptake. Protein analysis revealed increased hENT1 (P < 0.0963) in MDA-MB231. Hypoxia did not change expression of either hENT1, hENT2, or TK1. In vitro inhibition experiments suggested involvement of hENT1, hENT2, and human concentrative nucleoside transporters during [18F]FLT uptake into all cell lines. In vivo PET imaging revealed comparable tumor uptake in MCF7 and MDA-MB231 tumors over 60 min, reaching standardized uptake values of 0.96 ± 0.05 vs. 0.89 ± 0.08 (n = 3). Higher hENT1 expression in MDA-MB231 seems to drive nucleoside transport, whereas TK1 expression in MCF7 seems responsible for comparable [18F]FLT retention in ER+ tumors. Our study demonstrates that hypoxia does not significantly affect nucleoside transport as tested with [18F]FLT in BC.-Krys, D., Hamann, I., Wuest, M., Wuest, F. Effect of hypoxia on human equilibrative nucleoside transporters hENT1 and hENT2 in breast cancer.

ER-mediated anti-tumor effects of shikonin on breast cancer

Estrogen receptor (ER) is expressed in most Breast cancer (BC) patients. G protein-coupled estrogen receptor (GPER), which is a membrane-bound estrogen receptor, is associated with the tumor development and progression in BC. Shikonin (SK) is a natural compound that is known to have anti-tumor effects. This study aims to assess the effects of shikonin on the cell proliferation, cell cycle and cell apoptosis of BC and whether the effects are related to ER/GPER signaling pathway. The results demonstrated that shikonin inhibited the cellular proliferation of MCF-7 BC cells via G0/G1 arrest and apoptosis in concentration-dependent manner. The anti-proliferative effect of SK on SK-BR-3 BC cells was associated with apoptosis. Both ERα and GPER were expressed in MCF-7 cells, while ERα were negative and GPER were positive in SK-BR-3 cells. Furthermore, shikonin downregulated the expression of ERα and GPER, and this effect was not affected by the estrogen environment. In addition, shikonin downregulated the EGFR and p-ERK expression in MCF-7 and SK-BR-3, which was also not affected by the estrogen environment. EGFR and p-ERK were still suppressed by co-treatment with the selective GPER against G1 or antagonist G15. In conclusion, these results suggest that shikonin shows anti-tumor effects on MCF-7 and SK-BR-3 cells. The effects seem to be associated with EGFR/p-ERK downregulation via ERα and GPER inhibition.

Epidermal Growth Factor and Adenosine Triphosphate Induce Natrium Iodide Symporter Expression in Breast Cancer Cell Lines.

AIM:This study aims to investigate the effect of ATP, EGF and combination of those two to the Natrium Iodide Symporter (NIS) expression in MCF7, SKBR3 and HaCaT cell lines.METHODS:MCF7, SKBR3 and HaCaT cell lines were treated with ATP, EGF and combination of those two for 6, 12 and 24 hours. The expression of NIS mRNA was measured through quantitative-reverse transcription-polymerase chain reaction (qRT-PCR). The NIS protein expression was confirmed by immunocytofluorescence.RESULTS:NIS mRNA was expressed in SKBR3 and HaCaT cell lines but not in MCF7. The levels of NIS mRNA expression, after treatment by epidermal growth factor (EGF), adenosine Tri-Phosphate (ATP) or the combination of both for 6 and 12 hours were not significantly different from those of untreated cells. However, the treatment by a combination of ATP and EGF for 24 hours increases the level of NIS mRNA expression by 1.6 fold higher than that of the untreated cells (1.6241 ± 0.3, p < 0.05) and protein NIS expression increase significantly by the treatment than untreated cells (P < 0.05).CONCLUSION:The level of NIS expression varies among the different subtypes of breast cancer cell lines. MCF7 cell line is representing the luminal A subtype of breast cancer does not express NIS. Only SKBR3 cell line express NIS and this subtype might be suitable to receive radioiodine therapy as those cells expressing NIS. A combination treatment of EGF and ATP increases the expression of NIS mRNA and protein at the membrane in SKBR3 cells.

Abstract 3040: The expressional effects of RBBP6 in breast cancer cells are p53-dependent

Abstract The incidence rate of breast cancer has increased beyond that of lung cancer, making it the most common malignancy among women. Breast tumor progression is partly because of p53 inactivation by overexpressed that possess p53 binding domain. RBBP6 forms a member of ubiquitous regulatory proteins because its RING finger-like domain has an E3 ligase activity. The overexpression of RBBP6 in several malignancies makes it a potential target in cancer management. However, there is no evidence on whether the effect of RBBP6 on cell growth and apoptosis is cell line dependent, more especially in breast cancer cell lines that have distinct p53 expression profiles. Therefore, the aim of this study was to evaluate the RBBP6 effects on cell growth and apoptosis in breast cancer cell lines with different p53 expression profiles. RBBP6 expression was successfully manipulated using gene silencing and protein overexpression techniques in MCF-7 and MDA-MB-231 cell lines. Transfected cells were co-treated with anti-cancer agents followed by apoptosis detection using confocal microscopy and flow cytometry, which was further confirmed by caspase 3/7 activity and quantification of apoptotic genes. RBBP6 was overexpressed in breast cancer tissues that were classified as stage 3 and 4 while in stage 1 it was expressed but at much lower levels. The wt. p53-expressing MCF-7 cell line was more susceptible to apoptosis induction as opposed to the mt. p53-expressing MDA-MB-231. RBBP6 silencing led to a significant accumulation of p53 expression in MCF-7 as compared to MDA-MB-231. Co-treatment with GABA and camptothecin seemed to sensitize the cells to apoptosis induction. These data suggest that RBBP6 silencing triggers significant levels of intrinsic apoptosis and over-expression appears to promote cell proliferation in wild-type p53-expressing MCF-7 rather than in MDA-MB-231 cells. In conclusion, the effect of RBBP6 on cell proliferation and apoptosis induction in breast cancer seem to be cell line dependent based on p53 status. Note: This abstract was not presented at the meeting. Citation Format: Pontsho Moela, Lesetja Motadi, Marcia Lekganyane. The expressional effects of RBBP6 in breast cancer cells are p53-dependent [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3040.

Abstract 4715: Combination of Tacedinaline and EHMT2 inhibition increases breast cancer cell death involving BIRC5 repression and GADD45A induction

Abstract The genomes of cancer cells are different from those of normal cells. These differences include genetic and epigenetic alterations, such as variations of DNA methylation and histone modifications, which cause differential gene expression, increased cell growth/migration capacity, and may induce resistance to anticancer therapy. Thus, epigenetic modulation may have a chance to correct abovementioned cancer cell’s aberrations in gene expression and cell behaviors, resulting in eradication of primary and/or suppression of refractory cancers. Tacedinaline (CI-994) and UNC0638 are specific inhibitors of class I histone deacetylase (HDAC) and histone methyltransferase EHMT2 (G9a), which cause an increase of histone acetylation and a decrease of histone H3 dimethylation at lysine 9, respectively. Here we examined the therapeutic effect of CI-994 and UNC0638 combination on the triple-negative (MDA-MB-231) and estrogen receptor-positive (MCF-7) breast cancer cell lines. The results showed that the combination of CI-994 and UNC0638 was able to induce more severe cell death than either agent alone. Although the sub-G1 fraction and Annexin V-positive cells were increased, CI-994 and UNC0638 did not significantly induce the activities of caspases 3, 8 and 9, suggesting the involvement of non-canonical and caspase-independent cell death mechanism. Instead, CI-994 suppressed the expression of BIRC5 (Survivin, a member of the inhibitor of apoptosis protein) and, in combination with UNC0638, induced the expression of GADD45A (involved in stress-induced apoptosis). Mechanistically, combination of CI-994 and UNC0638 resulted in the changes of epigenetic marks, such as acetylation and methylation of histone H3, at the loci of BIRC5 and GADD45A, which were correlated with their altered gene expressions. Genetic knockdown of BIRC5 expression in MCF-7 decreased cell viability, supporting the pro-survival role of BIRC5 in breast cancer cells. Importantly, the targets of CI-994 (HDAC1, HDAC2) and UNC0638 (EHMT2), as well as BIRC5 were overexpressed in breast cancer specimens, especially those of triple-negative breast cancer (TNBC), based on the analyses of The Cancer Genome Atlas dataset. Meanwhile, the expression of GADD45A was downregulated. BIRC5 upregulation and GADD45A downregulation in breast cancer were associated with patient’s overall survival. These results suggest that Tacedinaline and UNC0638, or targeting the class I HDAC and EHMT2, may be a potential strategy to treat breast cancer including TNBC. Citation Format: Pei-Yi Chu, Ji-Ching Lai, Ming-Feng Hou, Chang-Shen Lin. Combination of Tacedinaline and EHMT2 inhibition increases breast cancer cell death involving BIRC5 repression and GADD45A induction [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4715.

Effect of the key histone modifications on the expression of genes related to breast cancer

Abnormal histone modifications (HMs) and transcription factors (TFs) can alter the expression of cancer-related genes to promote tumorigenesis. We studied the variations of 11 HMs and 2 TFs in human breast cancer cells (MCF-7) compared to human normal mammary epithelial cells (HMEC), and the effects of HMs/TFs in various regions of the genome on the expression changes of breast cancer-related genes. Based on HMs and TFs signals' differences between MCF-7 and HMEC flanking TSSs, the up- and down-regulated genes in MCF-7 were predicted by Random Forest, and important HMs and regions were found. Results indicate that H3K79me2, H3K27ac, and H3K4me1 are particularly important for the changes of gene expression in MCF-7. Especially, H3K79me2 around the 60-th bin flanking TSSs may be the key for regulating gene expression. Our studies reveal H3K79me2 may be a core HM for breast cancer.

Research on Mechanism of FGFR1 Inhibitor BAY1163877 against Proliferation of Breast Cancer Cells

To investigate the effect and mechanism of fibroblast growth factor receptor 1 (FGFR1) inhibitor BAY1163877 on proliferation and apoptosis of breast cancer cells. The expression of FGFR1 in human breast cell lines was detected by qRT-PCR and western blot. IC50 of BAY1163877 and cell viability were measured by CCK-8 method. Cell proliferation was observed by colony assay. Cell apoptosis after treatment of BAY1163877 was tested by flow cytometry. The expressions of p-FGFR1/FGFR1 and p-STAT3/STAT3 protein were detected by Western blot. According to the results of qRT-PCR and Western blot, FGFR1 high expression of breast cancer cell line MDA-MB-231 and FGFR1 low expression of breast cancer cell line MCF-7 were selected. BAY1163877 inhibits proliferation of MDA-MB-231 and MCF-7 cells and induces apoptosis of MDA-MB-231 and MCF-7 cells. The results of Western blot showed that the expression of p-FGFR1 and p-STAT3 protein in MDA-MB-231 was reduced after BAY1163877 treatment and the expression in MCF-7 was not significantly changed. BAY1163877 inhibits the proliferation and induces the apoptosis of high FGFR1 expression breast cancer cell line MDA-MB-231, and its mechanism may be related to the decrease of p-FGFR1 and p-STAT3 protein expression. BAY1163877 inhibits the proliferation and induces the apoptosis of MCF-7, but its mechanism still needs the further study.

Ribosomal DNA as DAMPs Signal for MCF7 Cancer Cells

Introduction: The cell free ribosomal DNA (cf-rDNA) is accrued in the total pool of cell free DNA (cfDNA) in some non-cancer diseases and demonstrates DAMPs characteristics. The major research questions: (1) How does cell free rDNA content change in breast cancer; (2) What type of response in the MCF7 breast cancer cells is caused by cf-rDNA; and (3) What type of DNA sensors (TLR9 or AIM2) is stimulated in MCF7 in response to the action of cf-rDNA?Materials and Methods: CfDNA and gDNA were isolated from the blood plasma and the cells derived from 38 breast cancer patients and 20 healthy female controls. The rDNA content in DNA was determined using non-radioactive quantitative hybridization. In order to explore the rDNA influence on MCF7 breast cancer cells, the model constructs (GC-DNAs) were applied: pBR322-rDNA plasmid (rDNA inset 5836 bp long) and pBR322 vector. ROS generation, DNA damage, cell cycle, expression of TLR9, AIM2, NF-kB, STAT3, and RNA for 44 genes affecting the cancer cell viability were evaluated. The methods used: RT-qPCR, fluorescent microscopy, immunoassay, flow cytometry, and siRNA technology.Results: The ratio R = cf-rDNA/g-rDNA for the cases was higher than for the controls (median 3.4 vs. 0.8, p < 10−8). In MCF7, GC-DNAs induce a ROS burst, DNA damage response, and augmentation of NF-kB and STAT3 activity. The number of the apoptotic cells decreases, while the number of cells with an instable genome (G2/M– arrest, micronuclei) increase. Expression of anti-apoptotic genes (BCL2, BCL2A1, BCL2L1, BIRC3, MDM2) is elevated, while expression of pro-apoptotic genes (BAX, BID, BAD, PMAIP1, BBC3) is lowered. The cells response for pBR322-rDNA is much more intense and develops much faster, than response for pBR322, and is realized through activation of TLR9- MyD88 - NF-kB- signaling. This difference in response speed is owing to the heightened oxidability of pBR322-rDNA and better ability to penetrate the cell. Induction of TLR9 expression in MCF7 is followed by blocking AIM2 expression.Conclusion: (1) Ribosomal DNA accumulates in cfDNA of breast cancer patients; (2) Cell free rDNA induce DNA damage response and stimulates cells survival, including cells with an instable genome; (3) Cell free rDNA triggers TLR9- MyD88- NF-kB- signaling, with significantly repressing the expression of AIM2.

TAAR1 levels and sub-cellular distribution are cell line but not breast cancer subtype specific.

Trace amine-associated receptors are G protein-coupled receptors of which TAAR1 is the most well-studied. Recently, Vattai et al. (J Cancer Res Clin Oncol 143:1637-1647 https://doi.org/10.1007/s00432-017-2420-8 , 2017) reported that expression of TAAR1 may be a marker of breast cancer (BC) survival, with a positive correlation also suggested between TAAR1 expression and HER2 positivity. Neither a role for TAAR1 in breast tissue, nor in cancer, had previously been suspected. We, therefore, sought to provide independent validation and to further examine these putative relationships. First, a bioinformatic analysis on 58 total samples including normal breast tissue, BC-related cell lines, and tumour samples representing different BC sub-types found no clear correlation between TAAR1 mRNA levels and any BC subtype, including HER2 + . We next confirmed the bioinformatics data correlated to protein expression using a well validated anti-human TAAR1 antibody. TAAR1 mRNA levels correlated with the relative intensity of immunofluorescence staining in six BC cell lines (MCF-7, T47D, MDA-MB-231, SKBR3, MDA-MB-468, BT-474), but not in the MCF-10A immortalized mammary gland line, which had high mRNA but low protein levels. As expected, TAAR1 protein was intracellular in all cell lines. Surprisingly MCF-7, SKBR3, and MDA-MB-468 showed pronounced nuclear localization. The relative protein expression in MCF-7, MDA-MB-231, and MCF-10A lines was further confirmed by semi-quantitative flow cytometry. Finally, we demonstrate that the commercially available anti-TAAR1 antibody has poor selectivity, which likely explains the lack of correlation with the previous study. Therefore, while we clearly demonstrate variable expression and sub-cellular localization of TAAR1 across BC cell lines, we find no evidence for association with BC subtype.

C-Myc induced the regulation of long non-coding RNA RHPN1-AS1 on breast cancer cell proliferation via inhibiting P53.

The global burden of breast cancer has been increasing, the mechanism of which is related to multifactorial accumulation of gene mutations. Dysregulation of long noncoding RNA (LncRNA) has been linked to multiple kinds of tumorigenesis. We aimed to identify functionally relevant targets of RHPN1 Antisense RNA 1 (RHPN1-AS1) in breast cancer using breast cancer cell line-based model. Quantitative RT-PCR revealed higher expression levels of RHPN1-AS1 in human breast cancer tissues and cell line MCF-7. RHPN1-AS1 was also located in MCF-7 cells by fluorescence in situ hybridization and western blot assays. Knockdown of RHPN1-AS1 delivered by lentivirus system inhibited MCF-7 cell proliferation indicated by the cell proliferation and colony formation assays, and the knockdown of RHPN1-AS1 enhanced P53 protein expression in MCF-7 and MDA-MB-231 cells. In addition, luciferase reporter assay validated that RHPN1-AS1 is a molecular sponge of miR-4261, and direct transcriptional target of c-Myc. RHPN1-AS1 exerts tumorigenesis by regulating P53 expression via MDM2 gene. These findings provide insights into the role and mechanism of action of lncRNA RHPN-AS1 in breast cancer.

MON-038 The Effects of Isoliquiritigenin (ISL) on the Expression of Estrogen Receptor and Tumor Suppressor Genes BRCA-1 and P53 in Breast Cancer Cells

Naturally sourced treatments are increasingly sought for health issues including breast cancer. Isoliquiritigenin (ISL), a phenolic flavonoid in licorice root, has recently received attention in public and scientific communities for its antioxidant, anti-inflammatory and tumor suppressive effects. Standard medical practice now includes determining receptor status of breast cancers and estimates show that 55-65% of women with a BRCA1 gene mutation will develop hereditary breast cancer, therefore finding treatment options for receptor-positive patients is critically important. This study examined the effects of ISL, alone and in combination with hormones and anti-hormones, on ERα, p53, and BRCA1 expression in MCF-7 and T-47D breast cancer cells by utilizing western blot analyses, cellular viability assays, confocal microscopy, apoptosis assay and RT-qPCR analyses. To ensure treatment conditions without the presence of endogenous steroids or growth factors, cells were cultured in a medium containing 5% charcoal-stripped fetal bovine serum (FBS) for a duration of 6 days. For western blot analyses, cells were treated with various concentrations of ISL ranging from 5-100 µM for 24 hours. Compared to the control, a concentration dependent decrease of ERα (85%) and BRCA1 (60%) was noted in both cell lines, while the expression of p53 seemed to be altered based on the specific breast cancer cell lines. In our hormone studies, we used the optimal concentration of 50μM ISL alone and in combination with hormones and anti-hormones. After 24-hour treatment of ISL, E2, and E2 with ISL on the breast cancer, cells showed a decrease in ERα and BRCA-1 expression compared to the control. Combination treatment of ISL with anti-hormone ICI revealed a significant down regulation (approximately 65-85%) of ERα, BRCA-1, and p53 in T-47D cells. The same treatment conditions in MCF-7 cells revealed a significant down regulation of ERα and BRCA-1, while p53 expression was up regulated. Image cytometric analysis with propidium iodide staining was performed to examine the effects that ISL has on cellular viability in T-47D and MCF-7 cells. Cells treated for 6 days with 50 μM ISL concentration with hormone and anti-hormones displayed a decrease in cell proliferation compared to the control in both cell lines. RT-qPCR studies revealed a transcriptional expression of ESR1 and BRCA-1 mRNA levels that correlate with the translational data obtained via western blot analyses. Cytolocalization studies are in progress and apoptosis assays are currently being performed to determine the mechanism(s) of cell death. Our studies offer an intriguing direction to explore the molecular mechanisms of ISL on the steroid receptors and tumor suppressor gene in breast cancer cells.