Normal Breast Epithelial Cell Line Research Articles

MiR-301b-3p promotes breast cancer development through inhibiting the expression of transforming growth factor-beta receptor 2.

Breast cancer (BC) is a serious health threat to the patients. The present work explored the mechanism of miR-301b-3p and transforming growth factor-beta receptor 2 (TGFBR2 ) in affecting BC progression. The miR-301b-3p-inhibitor and si-TGFBR2 solution were added to the DEME/F12 medium to culture the BC and normal breast epithelial cell lines to prepare negative control, miR-301b-3p-IN and miR-301b-3p-IN+si-TGFBR2 in the two types of cell lines. The relative expression of target genes and the interference effect were analyzed by quantitative real-time PCR (qRT- PCR). Cell viability was detected applying cell counting kit-8 (CCK-8) assay. Transwell and wound healing assay were conducted to evaluate the invasion and migration of BC cells after miR-301b-3p inhibition. Additionally, cell apoptosis and the expression STAT protein were measured by flow cytometry and Western blot, respectively. The qRT-PCR results showed that miR-301b-3p were high-expressed but the level of TGFBR2 was significantly inhibited in BC cells. The miR-301b-3p-inhibitor significantly downregulated the expression of miR-301b-3p and upregulated that of TGFBR2. Meanwhile, inhibition of miR-301b-3p suppressed the cell viability, invasion, and migration of BC cells, which, however, were restored by the inhibition of TGFBR2. MiR-301b-3p conferred anti-apoptosis ability to BC cells, while TGFBR2 promoted apoptosis of BC cells through producing an antagonistic effect with miR-301b-3p. We found that miR-301b-3p played a crucial role in the phosphorylation of STAT1 and STAT3 to promote BC progression. The present findings demonstrated that miR-301b-3p played a crucial role in promoting BC cell growth, invasion and migration and anti-apoptosis, and that targeting TGFBR2 could inhibit the tumor-promoting effect of miR-301b-3p.

DDX5-Targeting Fragile X Mental Retardation Protein Regulates the Wnt/β-catenin Signaling Pathway to Promote Epithelial Mesenchymal Transition in Breast Cancer

To investigate the role of fragile X mental retardation protein (FMRP) in promoting cell migration and epithelial-mesenchymal transition (EMT) in breast cancer (BC) and the potential mechanisms involved. The mRNA and protein expressions of FMRP in MCF-10A, a normal human breast epithelial cell line, and four breast cancer cell lines, including MCF-7, BT474, MDA-MB-231, and HCC1937, were analyzed by RT-PCR and Western blot. The expression of FMRP in BC tissues was measured by immunohistochemistry (IHC). FMRP expression in BC and its relationship with clinical prognosis were analyzed using GEO database. Lentiviral infection and siRNA interference were used to construct FMRP overexpression and interference vectors, respectively, and the human breast cancer cell line MCF-7 was subsequently transfected. A Control group, an interference empty vector group (the NC group), a knockdown vector group (the siFMRP group), an overexpression empty vector group (the Lv-NC group), and an overexpression vector group (the Lv-FMRP group) were set up. The migration and invasion abilities of the cells were assessed by scratch assay and Transwell assay. The expression of EMT markers, including E-cadherin, an epithelial marker, N-cadherin, an mesenchymal markers, vimentin, zinc finger E-box binding homeobox 1 (ZEB1), and snail family zinc finger 2 (Slug), in the cells of each group was determined by Western blot. The interaction between FMRP and DEAD-box RNA helicase-5 (DDX5) protein was analyzed by immunocoprecipitation combined with mass spectrometry (IP-MS). The regulatory effect of FMRP on DDX5 protein expression was assessed using the protein synthesis inhibitor cycloheximide (CHX) and proteasome inhibitor MG132. In addition, transfection with siDDX5 vector was conducted to observe whether DDX5 could reverse the effects of FMRP overexpression on cell migration and EMT. The localization and expression of β-catenin were determined by immunofluorescence staining, and the expression of core markers of Wnt/β-catenin signaling pathway was examined by Western blot. FMRP was highly expressed in BC tissues and cells (P<0.05), and overall survival (OS) and recurrence-free survival (RFS) of the FMRP high expression group were significantly lower than those of the FMRP low expression group (P<0.05). The migration ability of MCF-7 cells was weakened after FMRP knockdown, while overexpression of FMRP promoted cell migration (P<0.05). After FMRP knockdown, the expression of E-cadherin was increased, while the expression levels of N-cadherin, vimentin, ZEB1, and Slug were decreased, which inhibited the occurrence of EMT. In contrast, the overexpression of FMRP promoted the EMT process (P<0.05). FMRP interacted with DDX5 protein and promoted DDX5 protein stability by blocking the ubiquitin-proteasome pathway. DDX5 knockdown reversed the effect of FMRP overexpression to promote cell migration and EMT (P<0.05), effectively inhibited β-catenin nuclear translocation, and decreased β-catenin nuclear distribution. Furthermore, it was found that the expression of p-β-catenin, GSK3β and Axin2 protein was increased and the expression of C-myc protein was decreased after DDX5 downregulation (P<0.05). On the other hand, the expression of these proteins was reversed by combined FMRP overexpression (P<0.05). FMRP targets DDX5 and promotes BC cell migration and EMT via the activation of the Wnt/β-catenin signaling pathway.

Exosomal HMGB1 educate PD-L1+-tumor associated macrophages via glycometabolic reprogramming to induce lung-tropic metastasis of triple negative breast cancer.

1090 Background: Lung metastasis occurs in one third of triple negative breast cancer (TNBC), the underlying molecular mechanism remains largely unclear. Mounting evidence suggests that PD-L1+-tumor associated macrophages (PD-L1+-TAMs) are closely associated with immune suppression, invasion, and metastasis. Tumor-derived exosomes have been reported to remodel tumor microenvironment and accelerate metastasis through packing and delivering a variety of biologically active molecules. The aim of this study was to investigate whether TNBC-derived exosomes were able to polarize lung macrophages towards PD-L1+-TAMs and promote a pre-metastatic immunosuppressive niche, therefore discovering the underlying mechanism of lung-tropic metastasis. Methods: Exosomes obtained from EO771 TNBC cell line (EO771/exo) and HC11 normal breast epithelial cell line (HC11/exo) were characterized. Absorption of exosomes by macrophages was observed by confocal microscopy. Mass spectrometry was used to identify the significantly highly expressed HMGB1 protein in EO771/exo, and ligands of HMGB1 on lung macrophages were detected by co-immunoprecipitation. Significance of EO771/exo and HMGB1 in inducing PD-L1+-TAMs and generating a pre-metastatic immunosuppressive niche were confirmed by both in vitro and in vivo studies. Functions of EO771/exo and HMGB1 on glycolysis and lactate production were evaluated by metabolism assays. Results: EO771/exo could polarize macrophages toward PD-L1+-TAMs and generate a pre-metastatic immunosuppressive niche. Mass spectrometry, clinical samples, and bioinformatics analysis showed that HMGB1 was significantly expressed in EO771/exo and was involved in cellular communication and metabolism processes. Co-immunoprecipitation and 3-dimensional modeling suggested a strong binding of HMGB1 with Tim-3 ligand on lung macrophages. Macrophages incubated with EO771/exo exhibited an enhanced glycolysis and lactate production. Flow cytometry demonstrated that green fluorescent protein (GFP)-EO771 tumor-bearing mice had more lung micro-metastases than brain and liver. Immunofluorescence and laser confocal microscopy demonstrated that EO771/exo were able to increase lung micro-metastases and escalate PD-L1 expression on lung macrophages. Moreover, elevated PD-L1+-TAMs and reduced CD3+CD8+ T lymphocytes were detected in TNBC positive axillary lymph nodes and lung metastasis specimens than TNBC negative axillary lymph nodes. Conclusions: Exosomal HMGB1 from TNBC could target Tim-3 ligand on lung macrophages and accelerate glycolysis and lactate production to induce PD-L1+-TAMs, thereby suppressing CD3+CD8+ T lymphocytes immunity and generating a pre-metastasis immune-suppressive niche. Our research would uncover a novel mechanism of lung-tropic metastasis.

Abstract PO1-06-11: Exosomal HMGB1 induce PD-L1+-tumor associated macrophages through glycometabolic reprogramming to promote lung-tropic metastasis of triple negative breast cancer

Abstract Background: Lung metastasis occurs in 30% of triple negative breast cancer (TNBC), the detailed molecular mechanism remains largely unexplored. Accumulating evidence suggests that PD-L1+-tumor associated macrophages (PD-L1+-TAMs) are closely related to immune suppression, invasion, and metastasis. Tumor-derived exosomes have been reported to remodel tumor microenvironment and accelerate metastasis via packing and delivering a variety of biologically active molecules. Our previous studies found that exosomes from breast cancer cells polarized macrophages toward TAMs within the primary tumor nest. The aim of this study was to reveal whether TNBC-derived exosomes were able to polarize lung macrophages towards PD-L1+-TAMs and generate a pre-metastatic immunosuppressive niche, therefore discovering the underlying mechanism of lung-tropic metastasis. Methods: Exosomes isolated from EO771 TNBC cell line (EO771/exo) and HC11 normal breast epithelial cell line (HC11/exo) were characterized. Uptake of exosomes by macrophages was visualized by confocal microscopy. Mass spectrometry was applied to identify the significantly highly expressed HMGB1 protein in EO771/exo, and ligands of HMGB1 on lung macrophages were detected by co-immunoprecipitation. Functions of EO771/exo and HMGB1 in inducing PD-L1+-TAMs and generating a pre-metastatic immunosuppressive niche were confirmed by both in vitro and in vivo studies. Roles of EO771/exo and HMGB1 on glycolysis and lactate production were evaluated by metabolism assays. Associations between PD-L1+-TAMs and CD3+CD8+ T lymphocytes within TNBC axillary lymph nodes and lung metastasis specimens were analyzed by immunofluorescence and immunohistochemistry. Results: Confocal microscopy showed constant internalization and absorption of EO771/exo by macrophages. EO771/exo could polarize macrophages toward PD-L1+-TAMs and generate a pre-metastatic immunosuppressive niche, with respect to HC11/exo. Mass spectrometry, clinical samples, and bioinformatics analysis revealed that HMGB1 was highly expressed in EO771/exo and was involved in cellular communication and metabolism processes. Co-immunoprecipitation and 3-dimensional modeling indicated a strong binding of HMGB1 with Tim-3 ligand on lung macrophages. Macrophages treated with EO771/exo displayed an enhanced glycolysis and lactate production. Flow cytometry demonstrated that green fluorescent protein (GFP)-EO771 tumor-bearing mice had more lung micro-metastases than brain and liver. Immunofluorescence and laser confocal microscopy confirmed that EO771/exo, with respect to HC11/exo, were able to increase lung micro-metastases and escalate PD-L1 expression on lung macrophages. Moreover, elevated PD-L1+-TAMs and reduced CD3+CD8+ T lymphocytes were found in TNBC positive axillary lymph nodes and lung metastasis specimens than TNBC negative axillary lymph nodes. Conclusions: Exosomal HMGB1 from TNBC could target Tim-3 ligand on lung macrophages and accelerate glycolysis and lactate production to induce PD-L1+-TAMs, thereby suppressing CD3+CD8+ T lymphocytes immunity and generating a pre-metastasis immune-suppressive niche. Our research would uncover a novel mechanism of lung-tropic metastasis and provide a new therapeutic approach for TNBC treatment. Keywords: breast cancer; lung metastasis; exosomes; tumor-associated macrophages; metabolic reprogramming Citation Format: Wei-Xian Chen, Jia-Hao Wu, Tian-Cheng Cheng, Sujin Yang. Exosomal HMGB1 induce PD-L1+-tumor associated macrophages through glycometabolic reprogramming to promote lung-tropic metastasis of triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-06-11.

Encapsulation and Delivery of Mitoxantrone Using Zirconium-Based Metal–Organic Frameworks (MOFs) and Their Cytotoxic Potential in Breast Cancer Cells

Mitoxantrone (MTX) is a drug employed in breast cancer treatment, but its application is largely limited due to side effects. A controlled delivery approach can potentially reduce the side effects. In this study, two zirconium (Zr)-based MOFs, UiO-66 and UiO-66-NH2, were studied for a more controlled delivery of MTX with a 40% and 21% loading capacity, respectively. Characterisation via powder X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectrometry, scanning electron microscopy, and dynamic light scattering confirmed the integrity of structure post-MTX loading. UV–vis spectrophotometry revealed distinctive release profiles, with UiO-66-MTX exhibiting a 25% cumulative release after 96 h in water and 120 h in PBS +10% FBS. UiO-66-NH2-MTX displayed a more sustained release, reaching 62% in water and 47% in PBS +10% FBS after 168 h. The interaction between MTX and the MOFs was also proposed based on computational modelling, suggesting a stronger interaction of UiO-66NH2 and MTX, and an optimised interaction of MTX in the tetrahedral and octahedral pores of the MOFs. The study also reports the release profile of the drug and antiproliferative activity against a panel of breast cancer cell lines (MDA-MB-231, MDA-MB-468, and MCF7) and a normal breast epithelial cell line (MCF10A). MTX-encapsulated MOFs were thoroughly characterised, and their biological activity was assessed in vitro. MTT cell viability assay indicated a higher IC50 value for MTX-loaded MOFs compared to free MTX in physiological conditions, albeit with a slower release profile. These findings suggest the potential of these MTX-loaded MOFs as an alternative avenue for formulation to mitigate side effects.

An analysis of the prognostic role of reactive oxygen species-associated genes in breast cancer.

This study aimed to type breast cancer in relation to reactive oxygen species (ROS), clinical indicators, single nucleotide variant (SNV) mutations, functional differences, immune infiltration, and predictive responses to immunotherapy or chemotherapy, and constructing a prognostic model. We used uniCox analysis, ConsensusClusterPlus, and the proportion of ambiguous clustering (PAC) to analyze The Cancer Genome Atlas (TCGA) data to determine optimal groupings and obtain differentially expressed ROS-related genes. Clinical indicators were then combined with the classification results and the Chi-square test was used to assess differences. We further examined SNV mutations, and functional differences using gene set enrichment analysis (GSEA) analysis, the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, immune cell infiltration, and response to immunotherapy and chemotherapy. A prognostic model for breast cancer was constructed using these differentially expressed genes, immunotherapy or chemotherapy responses, and survival curves. RT-qPCR was used to detect the differences in the expression of LCE3D, CA1, PIRT and SMR3A in breast cancer cell lines and normal breast epithelial cell line. We identified two distinct tumor types with significant differences in ROS-related gene expression, clinical indicators, SNV mutations, functional pathways, and immune infiltration. The response to specific chemotherapy drugs and immunotherapy treatments also documented significant differences. The prognostic model constructed with 16 genes linked to survival could efficiently divide patients into high- and low-risk groups. The high-risk group showed a poorer prognosis, higher tumor purity, distinct immune microenvironment, and lower immunotherapy response. RT-qPCR results showed that LCE3D, CA1, PIRT and SMR3A are highly expressed in breast cancer. Our methodical examination presented an enhanced insight into the molecular and immunological heterogeneity of breast cancer. It can contribute to the understanding of prognosis and offer valuable insights for personalized treatment strategies. Further, the prognostic model can potentially serve as a powerful tool for risk stratification and therapeutic decision-making in clinical settings.

Abstract A089: Role of Vardhamana Pippali Rasayana (VPR) in human breast cancer cells

Abstract Serious concerns include delayed diagnosis and adverse side-effects of conventional treatment leading to residual morbidity in Breast cancer (BC) globally. Traditional Indian medicines/herbs via combination of conventional cancer are gaining increasing acceptance worldwide, playing a pivotal role as proven by their efficacy evaluation studies. Many plants are known to reduce the cell proliferation and tumor development after their treatment. Vardhamana Pippali Rasayana (VPR), an Ayurvedic herbal preparation of pippali (Piper longum) in gradually increasing and tapering dose is used to treat many cancers without any adverse side-effects. However, its anti-cancer role in breast cancer is not known yet. The present study has explored the cytotoxic and apoptotic effects of VPR in triplicates on human breast cancer (MCF7) and normal breast epithelial (MCF10A) cell lines at different concentrations after extracting piperine in aqueous and hydro-alcoholic soxhlet extract (0.25 to 50 μg/μl). The cytotoxic activity was carried out by MTT assay and results showed that a low IC50 was observed at 3.75 μg/μl of VPR against MCF-7 as compared with normal breast epithelial cells. Detection of apoptotic cells using suitable Annexin V was done and there was a time-dependent increase in percentage of annexin V positive cells upon treatment. The above results indicate that VPR may have a strong anti-cancerous potential. But other functional assays are warranted to validate the efficacy of the drug against breast cancer which are under progress in our laboratory. Citation Format: Dr.Richa Tripathi, Shivam Singh, Subhash Gupta, VG Huddar, Tanuja M Nesari, Ashok Sharma. Role of Vardhamana Pippali Rasayana (VPR) in human breast cancer cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A089.

Downregulation of MALAT1 in triple-negative breast cancer cells

BackgroundMALAT1 is one of the most abundant nuclear long non-coding RNAs, which has been found to be elevated in various types of cancers. However, conflicting reports on MALAT1 in breast cancer cell lines challenge understanding of MALAT1's involvement in breast cancer progression. AimMeasurement of normalized relative quantity (NRQ) of MALAT1 transcripts in cell lines representing triple-negative breast cancer (TNBC) and luminal breast cancer. Materials and methodsThe studies were performed using cell lines representing luminal breast cancer (T47D, MCF-7), TNBC (MDA-MB-468, CAL-51, MDA-MB-231), and MCF-10A cell line of normal breast epithelial cells. Total RNA was isolated from six independent cell cultures of each line, treated with DNase I, and used to synthesize complementary DNA, which was used in quantitative real-time PCR (qPCR) assays. Four MALAT1 fragments and reference genes CCSER2, ANKRD17, PUM1, GAPDH were amplified. ResultsGeometric means of the NRQ of MALAT1 in breast cancer cell lines had the shortest 95% confidence intervals when CCSER2 was used for normalization. MALAT1 major transcript levels thus estimated in TNBC cell lines were found to be statistically significantly reduced compared to levels in both MCF-10A cells and luminal breast cancer cell lines, while MALAT1 minority splice variants were found to be increased in almost all breast cancer cell lines. ConclusionCCSER2-normalized qPCR results indicate MALAT1 downregulation in cell lines representing the more aggressive breast cancer subtype compared to both the normal breast epithelial cell line and the estrogen receptor-positive breast cancer cell lines.

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 &lt;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 &lt;0.01). Patients with high LncRNA SCHLAP1 expression had a significantly lower two-year survival rate (P &lt;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 &lt;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.

Expression and Clinical Significance of TIGIT in Primary Breast Cancer.

The roles of T cell immunoreceptor with Ig and ITIM domains (TIGIT) in the diagnosis of primary breast cancer (PBC) are still unclear. This study was designed to investigate the expression of TIGIT in PBC patients, with an aim to analyze its diagnostic value in PBC. We first explore the expression of TIGIT in cancer patients based on TCGA database, and then we analyzed its correlation with clinicopathological features. Afterwards, we compared the protein and mRNA expressions of TIGIT in two BC cell lines (MCF-7 and MDA-MB-231) and normal breast epithelial cell line (MCF-10A). Subsequently, 56 PBC female patients admitted to the Taizhou People's Hospital from October 2018 to June 2021 were included in this study. Flow cytometry was used to detect TIGIT level on peripheral blood CD3+ T cells of PBC patients and healthy controls. TIGIT expression in PBC tissues was detected by immunohistochemistry (IHC) and immunofluorescence staining. TCGA database showed that compared with adjacent tissues, TIGIT was significantly upregulated in tumor tissues. High TIGIT expression was positively correlated with tumor stage and negatively correlated with recurrence free survival (RFS) and overall survival (OS). TIGIT level in BC cell lines, peripheral blood and tumor tissues of PBC patients was significantly higher than that of control (P < 0.05). TIGIT level was correlated with age (P < 0.05), rather than tumor size, pathological type, lymph node metastasis, ER, PR, HER-2, and P53. ROC curve showed that the optimal critical value of peripheral blood TIGIT for BC screening was 23.38%. Postoperative TIGIT level in peripheral blood was significantly decreased compared to the preoperative TIGIT level (P < 0.05). TIGIT was upregulated in PBC and was correlated with age. It may be a potential target for the diagnosis and immunotherapy of PBC.

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.

Abstract P5-11-03: Knockdown of TMEM45A regulates malignant progression of triple-negative breast cancer by inhibiting TGF-β/Smad signaling pathway-mediated EMT

Abstract Objectives: The incidence of breast cancer has jumped to first place in the global malignant tumor. As an essential component of the TMEM family, TMEM45A is abnormally highly expressed in some malignant tumors, and plays a role in promoting and regulating the occurrence and development of tumors. This study analyzed the expression of TMEM45A in breast cancer tissues and breast cancer cell lines, and explored the relationship with clinical subtypes. To examine the effects of TMEM45A on TNBC cell proliferation, migration, invasion and other biological functions, and to preliminarily clarify the molecular mechanism of TMEM45A regulating the epithelial-mesenchymal transition of TNBC cell lines. Methods: 1. Download and analyze the TCGA database, analyze the difference in the expression of TMEM45A in normal breast tissue and different subtypes of breast cancer tissue, and detect the protein expression level of TMEM45A in 8 pairs of cancer tissues and adjacent tissues by western blot experiment. 2. Detection of TMEM45A protein expression in normal breast epithelial cell line MCF10A and five breast cancer cell lines (MCF-7, MDA-MB-231, BT-549, MDA-MB-468, SK-BR-3) by western blot experiment. 3. Using small interfering RNA technology to down-regulate the protein expression levels of MDA-MB-231 and BT-549 TNBC cell lines with relatively high TMEM45A expression. The changes in cell proliferation ability were detected by CCK8 assay and clone formation assay, and the changes in cell migration ability and invasion ability were detected by wound healing assay and transwell assay, respectively. 4. After down-regulating TMEM45A in two TNBC cell lines, the expression changes of epithelial cell phenotype marker E-cadherin, mesenchymal phenotype marker N-cadherin, Vimentin, and critical molecules in TGF-β/Smad signal transduction pathway (TGFβ1, Smad2, Smad3, p-Smad2, p-Smad3) were detected by western blot experiment. Results: 1. Based on the TCGA database, the results showed that the expression level of TMEM45A mRNA in breast cancer was significantly higher than in normal breast tissue. The expression level of TMEM45A mRNA in any breast cancer subtype was higher than that in normal breast tissue, and it was the highest in the TNBC subtype. In the results of western blot experiments of clinical breast cancer specimens, the expression of TMEM45A in breast cancer tissues was significantly higher than that in the corresponding adjacent tissues, which further confirmed the reliability of the results of the TCGA database. 2. In normal breast epithelial cell line MCF10A and five breast cancer cell lines, MCF10A has the lowest expression level of TMEM45A protein. Among the five breast cancer cell lines, MDA-MB-231 had the highest expression of TMEM45A, followed by BT-549. 3. CCK8 assay, clone formation assay, wound healing assay and transwell assay showed that down-regulating TMEM45A protein levels in the two TNBC cell lines could significantly reduce cell proliferation, migration and invasion abilities. 4. After down-regulating TMEM45A protein levels in two TNBC cell lines, EMT-related indicators E-cadherin protein expression levels increased, N-cadherin and Vimentin protein expressions decreased, and the expression levels of essential protein molecules Smad2 and Smad3 in the TGF-β/Smad signal transduction pathway did not change significantly, while p-Smad2, p-Smad3 and TGF-β1 protein expressions decreased. Conclusions: TMEM45A is relatively highly expressed in breast cancer tissues and cell lines, especially in the subtype of TNBC. Down-regulation of TMEM45A expression can inhibit the proliferation, migration and invasion of TNBC cell lines. Mechanistically, TMEM45A may reverse EMT by inhibiting the activity of the TGF-β/Smad pathway. Citation Format: Yingkun Xu, Shengchun Liu. Knockdown of TMEM45A regulates malignant progression of triple-negative breast cancer by inhibiting TGF-β/Smad signaling pathway-mediated EMT [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-11-03.

Sequential coupling of phases in unjamming transition of epithelial cells via spatiotemporal analysis on physical phenotypes.

Changes in cellular phenotypes are noticeable traits of various pathophysiological events, including cancer metastasis, morphogenesis, and tissue regeneration. For instance, epithelial cells undergo distinct phenotypic transitions known as jamming and unjamming, which correspond to the cessation and awakening of the cell motility, respectively. When epithelial cells become crowded, the pack of cells is halted and maintains the hexagonal shape resulting in a well-designed barrier function. In contrast, the jammed epithelial cells regain motile functions when the cell is exposed to external cues such as growth factors, physical pressure, and empty spaces. Especially, cell migration, a key component for processing pathophysiological situations, requires the unjamming transition (UJT) as a prerequisite. While many researchers have investigated UJT recently, UJT remains largely unexplored. Here, we attempt to induce the UJT of the normal breast epithelial cell line (MCF 10A) by introducing the empty spaces after the cells are densely jammed. The MCF10A monolayer encounters the spaces, cells near the boundary initiate migration toward the empty region and transmits the migratory behavior to the posterior cells. If the cells are simply assumed to be linked particles, the migration transmission will occur gradually. However, the migration of cells in the rear part is formed at a certain time and location. To clarify the intriguing transition in the cellular motility of follower cells, we spatiotemporally quantify physical characteristics, including traction force, intercellular stress, and morphology of constituent cells. The extensive analysis on correlations between physical variables suggests that the UJT of epithelial cells begins with the accumulation of intercellular stress and completes with the cell division-driven relaxation of stress. In conclusion, this study successively proposes the integrated mechanism of UJT, that inclusively involves cell division, traction force, and cellular morphology.

Atractylenolide I Inhibits Triple-Negative Breast Cancer Cell Proliferation and Promotes Apoptosis via Blocking the Janus Kinase 2/Signal Transducer and Activator of Transcription 3 Signaling Pathway

Bioactive agent Atractylenolide I (AT-1) has been shown to possess therapeutic value for treating various malignancies. The purpose of the current study is to clarify the potential effect of AT-1 on the development of triple-negative breast cancer (TNBC) and to investigate relevant signaling pathways involved in its mechanism. MTT assay was used to assess the effect of different concentrations of AT-1 on cell survival rate in MCF-10A normal breast epithelial cell line and MDA-MB-231 TNBC cell line. Exogenous IL-6 and WP1066 respectively acted as the agonist and the inhibitor of JAK2/STAT3. Determination of MDA-MB-231 cell viability, proliferation and apoptosis employed MTT, colony formation assay and TUNEL. Western blotting was conducted to measure the expression of proliferation- and apoptosis-related proteins. The viability of MCF-10A cells was unaffected by AT-1, whereas in MDA-MB-231 cells the proliferation level was decreased and the apoptosis level was increased after AT-1 treatment. IL-6 partially restored the expression of AT-1-blocked JAK2/STAT3, and WP1066 inhibited JAK2/STAT3 expression in combination with IL-6 and AT-1. Furthermore, compared with the AT-1 group, co-incubation of IL-6 and AT-1 partially restored the proliferative capacity and reduced the apoptosis of MDA-MB-231 cells, while WP1066 reversed these effects in combination with IL-6 and AT-1. AT-1 suppressed proliferation and promoted apoptosis in TNBC cells likely through inhibiting the activation of JAK2/STAT3 signaling pathway. The findings from this study may provide guidance for future studies on AT-1 and theoretical basis of AT-1 pharmacological activities.

Abstract 13: Novel CRISPR screening approach identifies regulators of cell-free DNA release in vitro

Abstract Despite the well-documented benefits of circulating tumor DNA (ctDNA) based liquid biopsy, including screening, prognostication, and treatment monitoring, there remain several concerns with its application. Chief among these concerns are imperfect sensitivity and specificity, particularly pre-diagnosis and after tumor resection, when ctDNA burden is low. Cell death, either through apoptosis or necrosis, has been the most widely accepted mechanism of DNA release. Recent studies have also suggested active release through extracellular vesicles as a paradigm for DNA release. However, this pathway remains highly debated in terms of its contribution, mechanism, and even credibility. To address the deficiencies in ctDNA detection in the clinic and the lack of basic mechanistic knowledge of cf/ctDNA release, we performed an in vitro CRISPR screen on MCF10A cells to identify regulators of DNA release. This normal breast epithelial cell line was chosen because MCF10A cells release DNA into cell culture media with a similar fragmentation pattern to that observed in human blood. After lentiviral infection with the genome-wide Brunello CRISPR-Cas9 knockout library, the population of knockouts identified in the genomic DNA of cells attached to the plates was compared to the population of knockouts found in the DNA released into the cell-depleted culture media. Genes with skewed representation were considered potential regulators of DNA release. Our analysis identified several genes in the TRAIL apoptotic pathway including FADD, as well as several genes encoding RNA-binding proteins including Sam68. Knockout of Sam68 and FADD in MCF10As, MDA-MB-468 breast cancer cells, and NCI-H841 lung cancer cells lead to decreases in DNA release. Previous studies have hypothesized that the fragment size of released DNA is dependent on release mechanism. However, the decreases observed in our knockout cell lines were not limited to a specific fragment size of DNA. Application of the small molecule apoptosis inhibitor Z-VAD-FMK also recapitulated the DNA release phenotype seen in our knockout cell lines. From these results, we conclude that apoptosis is the major source of DNA release from cancer cells, and that fragment size is not the indicator of release mechanism it has been presumed to be. Mechanistic studies of DNA release such as this could lead to the ability to modify the amount of ctDNA in circulation, which would significantly improve accurate detection in the clinic. Citation Format: Brad A. Davidson, Adam X. Miranda, Sarah Croessmann, Ben Ho Park. Novel CRISPR screening approach identifies regulators of cell-free DNA release in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 13.

Insight into drug sensitizing effect of diallyl disulfide and diallyl trisulfide from Allium sativum L. on paclitaxel-resistant triple-negative breast cancer cells

Ethnopharmacological relevanceAyurvedic practitioners and herbal healers in India and China have extensively used garlic (Allium sativum L.) to treat cancers. Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are major volatile organosulfur phytochemical constituents found in garlic. Aim of the studyTo find new insight into the drug sensitizing effect of DADS and DATS on paclitaxel (PTX)-resistant triple-negative breast cancer cells (TNBC/PR). Materials and methodsThis study estimates the non-toxic concentration of DADS and DATS against normal healthy breast epithelial cell line (MCF-12A) by using a trypan blue viability assay. Also, it evaluates the effect of DADS and DATS on the sensitization of established stable TNBC/PR cell clones (MDA-MB 231 PR and MDA-MB 468 PR) by MTT, BrdU incorporation, intracellular ROS, cell cycle, and apoptosis assays. ResultsThe results show that DADS and DATS are non-cytotoxicity against MCF-12A cells. Nevertheless, DADS and DATS have shown significantly high cytotoxicity against MDA-MB 231 PR and MDA-MB 468 PR cells. They also inhibited PTX-resistant cell proliferation by blocking the cell cycle. Further, they induced apoptosis by activation of caspase 3 and 9. N-acetyl cysteine pre-treatment inhibited DADS and DATS-induced intracellular ROS release. In silico study shows that DADS and DATS interact with a large extracellular loop (LEL) of CD151 with a binding energy of −4.0 kcal/mol and transmembrane domain (TM) with a binding affinity of 11.7 and 13.6 kcal/mol, respectively. They also inhibited the surface expression of CD151 in TNBC/PR cells. ConclusionThis study implies that DADS and DATS could be considered for sensitizing drug-resistant breast cancers.

Polyamine synthesis enzyme AMD1 is closely related to the tumorigenesis and prognosis of human breast cancer

Adenosylmethionine decarboxylase 1 (AMD1) has been implicated in carcinogenesis and tumor progression. However, the potential biomechanism and biological implications of AMD1 in breast cancer (BC) remain unclear. The purpose of this study was to investigate the effect of abnormal expression of AMD1 in BC. The expression of AMD1 in different human BC cell lines was studied by using western blotting and qRT–PCR. In vitro cell proliferation, clone formation, cell cycle and apoptosis assays were performed to explore the effect of AMD1 on cellular proliferation. Xenograft mouse models were established to elucidate the role of AMD1 in BC growth. The expression profiles of AMD1 in 28 pairs of BC tissues and adjacent noncancerous tissues (ANTs) were investigated by using western blotting and immunohistochemistry. The clinical implication and prognostic evaluation of AMD1 in BC were examined by excavating the online database. We found that the expression levels of AMD1 in BC cell lines were significantly higher than those in the normal human breast epithelial cell line MCF-10A. In addition, AMD1 potentiated proliferation, induced cell cycle progression and inhibited apoptosis in BC cells. Subcutaneous tumor xenografts also supported the promotive role of AMD1 in BC growth. We discovered that the level of AMD1 in BC tissues was significantly higher than that in ANTs. Using the online database, increased AMD1 was found to be associated with clinical indicators and predicted a poor prognosis in patients with BC. Our findings indicate that AMD1 elicits potent oncogenic effects on the malignant progression of BC. AMD1 might serve as a promising diagnostic biomarker and therapeutic target for patients with BC.

MiR‐379‐5p inhibits the proliferation, migration, and invasion of breast cancer by targeting KIF4A

BackgroundMany studies have shown that microRNAs (miRNAs) play an essential role in gene regulation and tumor development. This study aimed to explore the expression of miR‐379‐5p and its mechanisms of affecting proliferation, migration, and invasion in breast cancer (BC).MethodsMiRNAs and mRNAs expression data of BC and normal breast tissue samples were downloaded from the TCGA and GEO databases. qRT‐PCR was used to detect the expression of miR‐379‐5p in human normal breast epithelial cell lines and human BC cell lines. The proliferation ability of transfected cells was detected by colony formation and EdU assays. The mobility and invasion ability of transfected cells was measured by wound healing and transwell assays. The relative protein expression of transfected cells was detected by western blot. Dual luciferase reporter assay was performed to identify the targeted binding of miR‐379‐5p and KIF4A.ResultsMiR‐379‐5p was lowly expressed in BC tissue samples and BC cell lines. The target genes of miR‐379‐5p were involved in many cancer‐related signaling pathways. PPI analysis and the cytoHubba algorithm of Cytoscape identified 10 genes as the hub genes. Survival analysis showed that only KIF4A expression in 10 hub genes was significantly associated with the prognosis of BC patients and was significantly upregulated in BC. Overexpression of miR‐379‐5p inhibited proliferation, migration, and invasion in the BC cell line MDA‐MB‐231, which could be reversed by KIF4A.ConclusionsMiR‐379‐5p inhibits proliferation, migration, and invasion of BC by targeting KIF4A.

Diabetic Triple Negative Breast Cancer: Polyamine Enzymes, Ornithine decarboxylase and Spermine oxidase as Potential Targets

Breast cancer (BC) is the second leading cause of death in women. Co‐existence of diabetes and BC, termed diabetic BC, can be lethal, leading to higher mortality (15‐40%) than BC alone. In triple negative breast cancer (TNBC) patients, chance of TNBC recurrence is about 3 months, and chance of mortality can be as high as 75%. TNBC is highly refractive, heterogenous, and resistant to most chemotherapies. Polyamines, which are ubiquitous in most cells, and play a role in cell growth, have been shown to be elevated in cancer, though their role in diabetic BC has not been explored. We hypothesized that high glucose/diabetic conditions increase TNBC cell proliferation through modification of the enzymes (ornithine decarboxylase and spermine oxidase) in the polyamine pathway. The objective was to determine potential targets in the polyamine pathway to mitigate TNBC advancement in diabetic conditions. For this purpose, MDA‐MB‐231 (TNBC) and MCF10‐A (normal breast epithelial) cell lines were used. Both were treated with low (5mM) and high glucose (25mM) concentrations and effects on polyamine levels, polyamine enzyme, and cell proliferation were monitored. Polyamine levels were assayed using reverse phase high performance liquid chromatography. Cell proliferation was assessed using a fluorescence‐based assay, and polyamine enzyme expression was monitored at the mRNA and protein level using RT‐PCR and Western Blots. Samples were sent to Johns Hopkins University for polyamine enzyme activity analysis. Further, an approved inhibitor of polyamine synthesis, alpha‐difluoromethylornithine (a‐DFMO, 5mM) was used in combination with glucose treatments. Under diabetic/high glucose conditions, putrescine levels were elevated in MDA‐MB‐231 cells (135%), which correlated with higher cell proliferation (123%). Polyamine enzyme activity of ODC increased (from ~75 pMolCO2/hr/mg protein to ~150 pMolCO2/hr/mg protein) and SMOX decreased (from ~0.4 pMolH202/min/mg protein to ~0.06 pMolH202/min/mg protein) in concert with changes observed at protein levels with high glucose exposure. DFMO was effective in reducing polyamine levels and cell proliferation, however re‐supplementation of polyamines (spermidine and spermine) restored cell proliferation to that, indicating that DFMO is only cytostatic. MCF‐10A cells showed marked elevation in cell proliferation with high glucose. DFMO prevented this increase; however no apparent change was observed in polyamine levels. The polyamine biosynthetic enzymes (ornithine decarboxylase and spermine oxidase) play an active role in increasing cell proliferation under high glucose conditions in TNBC. Since DFMO caused only cytostatic effects, there is a need for a more targeted approach to regulate polyamine levels and mitigate TNBC growth under diabetic conditions.

Reduction of Metastasis via Epigenetic Modulation in a Murine Model of Metastatic Triple Negative Breast Cancer (TNBC).

Simple SummaryWe investigate the use of the small molecule epigenetic modulator 4SC-202 as a potential cancer therapeutic or adjuvant for Triple Negative Breast Cancer (TNBC). Epigenetic modulation involves alteration of the cellular phenotype without altering the genotype. Here, we investigate how 4SC-202 affects tumor growth, the ability of tumor cells to migrate, and the growth of tumors in vivo. This study demonstrates that 4SC-202 kills tumor cells, reduces their ability to migrate, and decreases metastasis of the tumor cells and tumor burden in a highly metastatic murine model of TNBC. These preclinical studies provide critical information on the potential efficacy of 4SC-202 as a potential therapeutic or adjuvant for TNBC.This study investigates the effects of a dual selective Class I histone deacetylase (HDAC)/lysine-specific histone demethylase 1A (LSD1) inhibitor known as 4SC-202 (Domatinostat) on tumor growth and metastasis in a highly metastatic murine model of Triple Negative Breast Cancer (TNBC). 4SC-202 is cytotoxic and cytostatic to the TNBC murine cell line 4T1 and the human TNBC cell line MDA-MB-231; the drug does not kill the normal breast epithelial cell line MCF10A. Furthermore, 4SC-202 reduces cancer cell migration. In vivo studies conducted in the syngeneic 4T1 model, which closely mimics human TNBC in terms of sites of metastasis, reveal reduced tumor burden and lung metastasis. The mechanism of action of 4SC-202 may involve effects on cancer stem cells (CSC) which can self-renew and form metastatic lesions. Approximately 5% of the total 4T1 cell population grown in three-dimensional scaffolds had a distinct CD44high/CD24low CSC profile which decreased after treatment. Bulk transcriptome (RNA) sequencing analyses of 4T1 tumors reveal changes in metastasis-related pathways in 4SC-202-treated tumors, including changes to expression levels of genes implicated in cell migration and cell motility. In summary, 4SC-202 treatment of tumors from a highly metastatic murine model of TNBC reduces metastasis and warrants further preclinical studies.