Inhibits Breast Cancer Proliferation Research Articles

Macrophage subtypes inhibit breast cancer proliferation in culture.

Macrophages are a highly plastic cell type that adopt distinct subtypes and functional states depending on environmental cues. These functional states can vary wildly, with distinct macrophages capable of displaying opposing functions. We sought to understand how macrophage subtypes that exist on two ends of a spectrum influence the function of other cells. We used a co-culture system with primary human macrophages to probe the effects of macrophage subtypes on breast cancer cell proliferation. Our studies revealed a surprising phenotype in which both macrophage subtypes inhibited cancer cell proliferation compared to cancer cells alone. Of particular interest, using two different proliferation assays with two different breast cancer cell lines, we showed that differentiating macrophages into a "pro-tumor" subtype inhibited breast cancer cell proliferation. These findings are inconsistent with the prevailing interpretation that "pro-tumor" macrophages promote cancer cell proliferation and suggest a re-evaluation of how these interpretations are made.

Isoliquiritigenin-infused electrospun nanofiber inhibits breast cancer proliferation and invasion through downregulation of PI3K/Akt/mTOR and MMP2/9 pathways

Mastectomy followed by chemotherapy and radiotherapy is the current treatment regimen for breast cancer (BC). However, these approaches have systemic side effects and often lead to ineffective treatment outcomes. Therefore, a novel controlled release system is required to prevent tumor recurrence. Isoliquiritigenin (ISL), a dietary flavonoid, was shown to be effective against BC in our laboratory. However, its hydrophobicity and low bioavailability limit its anti-BC efficacy. Thus, the present study was designed to fabricate electrospun ISL-nanofiber scaffolds (ISL-NF) that can inhibit breast cancer growth and migratory capacity of BC cells in vitro and in vivo. The ISL-NF was prepared using an advanced coaxial electrospinning-cryocutting method, and characterized. Various assays, including cell viability, transwell, would healing, western blotting, and staining, were employed to explore the underlying mechanisms. In vitro studies showed that ISL-NF treatment for 24 h significantly inhibited cell proliferation, and migration and improved apoptosis in various BC cell lines. ISL-NF also decreased the protein expression of PI3K, Akt, mTOR, matrix metalloproteinase (MMP)-2, and MMP-9, thereby inhibiting BC cell invasion. Consistent with the in vitro study, ISL-NF treatment decreased tumor size and weight and inhibited tumor migration in 4T1 tumor-bearing mice. Based on the study, we suggest that ISL-NF may be useful in the treatment of BC.

The anti-proliferative effects of a frankincense extract in a window of opportunity phase ia clinical trial for patients with breast cancer

PurposeBoswellic acids, active components of frankincense, suppress tumor proliferation in vitro with a strong clinical trial safety profile in patients with inflammatory diseases. We performed a Phase Ia window of opportunity trial of Boswellia serrata (B. serrata) in patients with breast cancer to evaluate its biologic activity and safety.MethodsPatients with invasive breast cancer were treated pre-operatively with B. Serrata (2400 mg/day PO) until the night before surgery for a median of 11 days (SD 6 days; range: 5–23 days). Paraffin-embedded sections from pretreatment diagnostic core biopsies and post-treatment surgical excisions were evaluated using a tunnel assay and immunohistochemistry staining with Ki-67 antibodies. A non-intervention retrospective control arm consisting of core and surgical tissue specimens from untreated patients was used to compare patients treated with B. Serrata. The change in proliferation and apoptosis between diagnostic core specimens and surgical specimens was compared between the control and treatment groups using a two-tailed paired t-test.ResultsTwenty-two patients were enrolled, of which 20 received treatment, and 18 had sufficient tissue for IHC. There was an increase in percent change in proliferation from core biopsy to surgical excision in the control group (n = 18) of 54.6 ± 21.4%. In the B. serrata-treated group there was a reduction in proliferation between core biopsy and excision (n = 18) of 13.8 ± 11.7%. This difference was statistically significant between the control and B. serrata-treated groups (p = 0.008). There was no difference in change in apoptosis. There were no serious adverse events related to the drug.ConclusionBoswellia serrata inhibited breast cancer proliferation and was well-tolerated in a Phase Ia window of opportunity trial.

Apolipoprotein L3 inhibits breast cancer proliferation and modulates cell cycle via the P53 pathway.

Background: Breast cancer is the second most common cause of cancer-related mortality globally. Apolipoprotein L3 (APOL3), a member of the apolipoprotein family, has been implicated in the pathogenesis of cardiovascular diseases. Nevertheless, the functions and underlying mechanisms of APOL3 in breast cancer have yet to be elucidated. Methods: The patient data were sourced from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. Quantitative real-time PCR (qRT-PCR), western blotting, and immunohistochemistry (IHC) assays were used to assess expression of APOL3. Cell proliferation rates were determined by Cell Counting Kit-8 (CCK-8) and colony formation assays. Flow cytometry was used to examine cell cycle distribution. Western blotting was conducted to investigate the expression of cell cycle related proteins. A xenograft model was used to evaluate the effect of APOL3 in vivo. APOL3-binding proteins were identified through mass spectrometry, co-immunoprecipitation (CO-IP) assay and immunofluorescence assay. Results: APOL3 expression was significantly downregulated in breast cancer, and its low expression was correlated with poor prognostic outcomes. Overexpression of APOL3 suppressed breast cancer cell proliferation, induced cell cycle disruption. Conversely, knockdown of APOL3 promoted cell proliferation. In vivo animal experiments demonstrated that APOL3 overexpression can inhibit tumor proliferation. Mass spectrometry, CO-IP and immunofluorescence assay confirmed the interaction between APOL3 and Y-box binding protein 1 (YBX1). Furthermore, YBX1 knockdown following APOL3 knockdown mitigated the enhanced proliferation. These results provide new ideas for clinically targeting APOL3 to inhibit proliferation in breast cancer. Conclusions: Our findings indicate that APOL3 inhibits breast cancer cell proliferation and cell cycle modulating P53 pathway through the interaction of YBX1.

Bruceine A inhibited breast cancer proliferation and metastasis by inducing autophagy via targeting PI3K-AKT signaling pathway.

Although there have been significant advances in cancer treatment, the urgent need to inhibit breast cancer metastasis remained unmet. Bruceine A (BA) is a natural compound extracted from Bruceae Fructus and has long been recognized to have antitumor effects with high safety and biocompatibility. However, the mechanisms and/or targets of BA for metastatic breast cancer treatment are still not fully elucidated. In this study, we systematically investigated the effects of BA on inhibition of breast cancer metastasis and its underlying mechanisms. We found that, in addition to its cytotoxic effects, BA significantly inhibited the invasion and migration capabilities of two types of breast cancer cell lines (MDA-MB-231 and MCF-7) while concurrently promoting apoptosis in these cells. Further mechanistic studies revealed that, by targeting the canonical PI3K-AKT signaling pathway, BA initiated autophagy of both types of breast cancer cell lines invitro. Invivo results further confirmed the invitro findings, manifested by shrinkage of size and weight of breast tumor as well as initiation of autophagy (indicated by upregulation of LC3I/II) through targeting PI3K-AKT pathway on mice model. These data collectively demonstrated the potential of BA in antimetastasis of breast cancer cells, suggesting its future clinical transformation in metastatic breast cancer therapy.

The p53/ZEB1-PLD3 feedback loop regulates cell proliferation in breast cancer

Breast cancer is the most prevalent cancer globally, endangering women’s physical and mental health. Phospholipase D3 (PLD3) belongs to the phosphodiesterase family (PLD). PLD3 is related to insulin-mediated phosphorylation of the AKT pathway, suggesting that it may play a role in the occurrence and development of malignant tumors. This study may further explore the molecular mechanism of PLD3 inhibiting breast cancer cell proliferation. In this study, we demonstrated that PLD3 and miR-6796 are co-expressed in breast cancer. PLD3 can bind with CDK1 and inhibit its expression, leading to mitotic arrest and inhibiting breast cancer proliferation. Wild-type p53 regulates PLD3 and miR-6796 expression by competitively binding to the PLD3 promoter with ZEB1. DNMT3B, as the target gene of miR-6796, is recruited into the PLD3 promoter by combining with ZEB1 to regulate the DNA methylation of the PLD3 promoter and ultimately affect PLD3 and miR-6796 expression. In conclusion, we revealed the role and molecular mechanism of PLD3 and its embedded miR-6796 in breast cancer proliferation, providing clues and a theoretical foundation for future research and development of therapeutic targets and prognostic markers for breast cancer.

Icariside I reduces breast cancer proliferation, apoptosis, invasion, and metastasis probably through inhibiting IL-6/STAT3 signaling pathway.

Breast cancer is a common malignancy in women. More than 90% of breast cancer deaths are caused by metastasis. Epimedii Folium (EF) is a commonly used herb with anti-tumor benefits, but its underlying mechanisms and active components for breast cancer prevention are little understood. This study assessed the therapeutic role of Icariside I (ICS I) in Epimedium flavonoids (EF) on lung metastasis of breast cancer, including the underlying mechanism. Western blot, RT-qPCR, wound healing assay, colony formation assay, and flow cytometry were used to investigate the inhibition of breast cancer cells growth and migration by EF and ICS I through disrupting the IL-6/STAT3 pathway. Combined with 4T1 breast cancer model in mice, Western blot, RT-qPCR, Hematoxylin and Eosin staining, immunohistochemistry were used to evaluate the therapeutic role of ICS I in proliferation, apoptosis, invasion, and metastasis of breast cancer. EF can inhibit STAT3 phosphorylation and reduce the colony formation and migration of breast cancer cells. Detecting the active ingredients in EF, we found ICS I can reduce the activation of STAT3 in 4T1 breast cancer cells, impair colony formation and migration. Moreover, ICS I induced cells G1 phase arrest and modulated Cyclin D1, CDK4, bcl-2, and bax to inhibit proliferation and survival of breast cancer cells. Similarly, the in vivo studies demonstrated that ICS I significantly suppressed tumor development and lung metastasis in the 4T1 mouse model. Tumor cells in vehicle group were arranged in a spoke-like pattern with obvious heterogeneity, and multinucleated tumor giant cells were seen. But, the tumor cells in the ICS I group were disorganized and necrotic lysis was seen in some areas. In ICS I-treated group, tumors' STAT3 phosphorylation level, IL-6, Cyclin D1, CDK4, bcl-2, and vimentin expression were downregulated, bax and cleaved caspase 3 expression were upregulated. In the lung tissue, we could find less metastasis of breast cancer cells and less lung injury in the ICS I group. Besides, the expression of metastasis-related genes MMP9 and vimentin was decreased in the lung tissue of ICS I group. These findings suggest that ICS I can inhibit breast cancer proliferation, apoptosis, invasion and metastasis probably via targeting IL-6/STAT3 pathway. Therefore, ICS I has the potential to become an innovative therapeutic candidate to breast cancer prevention and treatment.

Cyclometalated iridium(III) complexes as anti-breast cancer and anti-metastasis agents via STAT3 inhibition

Breast cancer is the most commonly diagnosed cancer and second‑leading cause of cancer deaths in women. Signal transducer and activator of transcription 3 (STAT3) plays a critical role in promoting breast cancer cell proliferation, invasion, angiogenesis, and metastasis, and the high expression of STAT3 is related to the occurrence and poor chemotherapy sensitivity of breast cancer. Iridium(III) complexes Ir-PTS-1– 4 containing a pterostilbene-derived ligand were synthesized to inhibit the STAT3 pathway in breast cancer. Ir-PTS-4 inhibited the proliferation of breast cancer cells by suppressing the expression of phosphorylated STAT3 and STAT3-related cyclin D1, arresting cell cycle in the S-phase, inducing DNA damage and reactive oxygen species (ROS) generation, eventually leading to autophagic cell death. The cell metastasis and invasion were also inhibited after Ir-PTS-4 treatment. Besides, Ir-PTS-4 exhibited excellent anti-proliferation activity in 3D multicellular tumor spheroids, showing potential for the treatment of solid tumors. This work presents the rational design of metal-based anticancer agents to block the STAT3 pathway for simultaneously inhibiting breast cancer proliferation and metastasis.

FAM129A Aggravates the Malignant Progression of Breast Cancer with the Synergistical Interaction with CXCL14

To detect differential levels of FAM129A and CXCL14 in breast cancer samples, and to explore their influences on breast cancer proliferation. Differential levels of FAM129A and CXCL14 in breast cancer samples were examined by qRT-PCR. The correlation between FAM129A level and clinic pathological factors in breast cancer patients was analyzed. The regulatory effects of FAM129A and CXCL14 on proliferative potential in highly invasive breast cancer cell lines MCF-7 and SKBR-3 were assessed by CCK-8 and EdU assay. The interaction between FAM129A and CXCL14 was explored by bioinformatics analysis and Dual-Luciferase reporter assay. FAM129A was upregulated in breast cancer samples, and it was positively correlated to TNM staging in breast cancer patients. Knockdown of FAM129A markedly attenuated in vitro proliferative ability in breast cancer. CXCL14 was lowly expressed in breast cancer tissues and cell lines, which was able to inhibit breast cancer proliferation. FAM129A could bind CXCL14 and negatively regulate its level in breast cancer samples. Rescue experiments demonstrated that knockdown of CXCL14 could abolish the inhibited proliferative ability in breast cancer cells with FAM129A knockdown. FAM129A is upregulated in breast cancer samples with highly invasive potential, and it is linked to TNM staging. It aggravates the malignant proliferation of breast cancer cells by targeting and downregulating CXCL14.

FOXA1 O-GlcNAcylation-mediated transcriptional switch governs metastasis capacity in breast cancer.

FOXA1, a transcription factor involved in epigenetic reprogramming, is crucial for breast cancer progression. However, the mechanisms by which FOXA1 achieves its oncogenic functions remain elusive. Here, we demonstrate that the O-linked β-N-acetylglucosamine modification (O-GlcNAcylation) of FOXA1 promotes breast cancer metastasis by orchestrating the transcription of numerous metastasis regulators. O-GlcNAcylation at Thr432, Ser441, and Ser443 regulates the stability of FOXA1 and promotes its assembly with chromatin. O-GlcNAcylation shapes the FOXA1 interactome, especially triggering the recruitment of the transcriptional repressor methyl-CpG binding protein 2 and consequently stimulating FOXA1 chromatin-binding sites to switch to chromatin loci of adhesion-related genes, including EPB41L3 and COL9A2. Site-specific depletion of O-GlcNAcylation on FOXA1 affects the expression of various downstream genes and thus inhibits breast cancer proliferation and metastasis both in vitro and in vivo. Our data establish the importance of aberrant FOXA1 O-GlcNAcylation in breast cancer progression and indicate that targeting O-GlcNAcylation is a therapeutic strategy for metastatic breast cancer.

A Novel Paclitaxel Derivative for Triple-Negative Breast Cancer Chemotherapy.

Paclitaxel-triethylenetetramine hexaacetic acid conjugate (PTX-TTHA), a novel semi-synthetic taxane, is designed to improve the water solubility and cosolvent toxicity of paclitaxel in several aminopolycarboxylic acid groups. In this study, the in vitro and in vivo antitumor effects and mechanisms of PTX-TTHA against triple-negative breast cancer (TNBC) and its intravenous toxicity were evaluated. Results showed the water solubility of PTX-TTHA was greater than 5 mg/mL, which was about 7140-fold higher than that of paclitaxel (<0.7 µg/mL). PTX-TTHA (10-105 nmol/L) could significantly inhibit breast cancer proliferation and induce apoptosis by stabilizing microtubules and arresting the cell cycle in the G2/M phase in vitro, with its therapeutic effect and mechanism similar to paclitaxel. However, when the MDA-MB-231 cell-derived xenograft (CDX) tumor model received PTX-TTHA (13.73 mg/kg) treatment once every 3 days for 21 days, the tumor inhibition rate was up to 77.32%. Furthermore, PTX-TTHA could inhibit tumor proliferation by downregulating Ki-67, and induce apoptosis by increasing pro-apoptotic proteins (Bax, cleaved caspase-3) and TdT-mediated dUTP nick end labeling (TUNEL) positive apoptotic cells, and reducing anti-apoptotic protein (Bcl-2). Moreover, PTX-TTHA demonstrated no sign of acute toxicity on vital organs, hematological, and biochemical parameters at the limit dose (138.6 mg/kg, i.v.). Our study indicated that PTX-TTHA showed better water solubility than paclitaxel, as well as comparable in vitro and in vivo antitumor activity in TNBC models. In addition, the antitumor mechanism of PTX-TTHA was related to microtubule regulation and apoptosis signaling pathway activation.

Cryptochrome 2 acetylation attenuates its antiproliferative effect in breast cancer

Breast cancer is the most commonly diagnosed cancer, and its global impact is increasing. Its onset and progression are influenced by multiple cues, one of which is the disruption of the internal circadian clock. Cryptochrome 2 (Cry2) genetic dysregulation may lead to the development of some diseases and even tumors. In addition, post-translational modifications can alter the Cry2 function. Here, we aimed to elucidate the post-translational regulations of Cry2 and its role in breast cancer pathogenesis. We identified p300-drived acetylation as a novel Cry2 post-translational modification, which histone deacetylase 6 (HDAC6) could reverse. Furthermore, we found that Cry2 inhibits breast cancer proliferation, but its acetylation impairs this effect. Finally, bioinformatics analysis revealed that genes repressed by Cry2 in breast cancer were mainly enriched in the NF-κB pathway, and acetylation reversed this repression. Collectively, these results indicate a novel Cry2 regulation mechanism and provide a rationale for its role in breast tumorigenesis.

Isopimaric acid, an ion channel regulator, regulates calcium and oxidative phosphorylation pathways to inhibit breast cancer proliferation and metastasis

Breast cancer is the globally most common malignant tumor and the biggest threat to women. Even though the diagnosis and treatment of breast cancer are progressing continually, a large number of breast cancer patients eventually develop a metastatic tumor, especially triple-negative breast cancer (TNBC). Recently, metal ion homeostasis and ion signaling pathway have become important targets for cancer therapy. In this study, We analyzed the effects and mechanisms of isopimaric acid (IPA), an ion channel regulator, on the proliferation and metastasis of breast cancer cells (4 T1, MDA-MB-231and MCF-7) by cell functional assay, flow cytometry, western blot, proteomics and other techniques in vitro and in vivo. Results found that IPA significantly inhibited the proliferation and metastasis of breast cancer cells (especially 4 T1). Further studies on the anti-tumor mechanism of IPA suggested that IPA might affect EMT and Wnt signaling pathways by targeting mitochondria oxidative phosphorylation and Ca2+ signaling pathways, and then inducing breast cancer cell cycle arrest and apoptosis. Our research reveals the therapeutic value of IPA in breast cancer and provides a theoretical basis for the new treatment of breast cancer.

Tetrahydrocurcumin regulates the tumor immune microenvironment to inhibit breast cancer proliferation and metastasis via the CYP1A1/NF-κB signaling pathway

The NF-κB signaling pathway is overactivated in tumor cells, and the activation of the NF-κB signaling pathway releases a large number of inflammatory factors, which enhance tumor immunosuppression and promote tumor metastasis. The cytochrome P450 (CYP450) system consists of important metabolic enzymes present in different tissues and progressive tumors, which may lead to changes in the pharmacological action of drugs in inflammatory diseases such as tumors. In this study, the anticancer effect of tetrahydrocurcumin (THC), an active metabolite of curcumin, on breast cancer cells and the underlying mechanism were investigated. Result showed that THC selectively inhibited proliferation and triggered apoptosis in breast cancer cells in a concentration- and time-dependent manner. Moreover, THC-induced cell apoptosis via a mitochondria-mediated pathway, as indicated by the upregulated ratio of Bax/Bcl-2 and reactive oxygen species (ROS) induction. In addition, THC could affect the CYP450 enzyme metabolic pathway and inhibit the expression of CYP1A1 and activation of the NF-κB pathway, thereby inhibiting the migration and invasion of breast cancer cells. Furthermore, after overexpression of CYP1A1, the inhibitory effects of THC on the proliferation, metastasis, and induction of apoptosis in breast cancer cells were weakened. The knockdown of CYP1A1 significantly enhanced the inhibitory effect of THC on the proliferation, metastasis, and apoptosis induction of breast cancer cells. Notably, THC exhibited a significant tumor growth inhibition and anti-pulmonary metastasis effect in a tumor mouse model of MCF-7 and 4T1 cells by regulating the tumor immunosuppressive microenvironment. Collectively, these results showed that TH could effectively trigger apoptosis and inhibit the migration of breast cancer cells via the CYP1A1/NF-κB signaling pathway, indicating that THC serves as a potential candidate drug for the treatment of breast cancer.

Dissecting the Functional Role of the TRIM8 Protein on Cancer Pathogenesis.

Simple SummaryThe tripartite motif (TRIM) gene family is a large group of E3 ubiquitin ligase proteins that can also have proteasome-independent functions. This review summarizes the structural organization, the biological functions and the mechanisms involved in cancer pathogenesis of TRIM proteins. Furthermore, this paper focuses on TRIM8, a member of the TRIM family proteins, describing its role both as a tumor suppressor and as an oncogene.TRIM/RBCC are a large family of proteins that include more than 80 proteins, most of which act as E3 ligases and catalyze the direct transfer of Ubiquitin, SUMO and ISG15 on specific protein substrates. They are involved in oncogenesis processes and in cellular immunity. On this topic, we focus on TRIM8 and its multiple roles in tumor pathologies. TRIM8 inhibits breast cancer proliferation through the regulation of estrogen signaling. TRIM8 downregulation in glioma is involved in cell proliferation, and it is related to patients’ survival. Several studies suggested that TRIM8 regulates the p53 suppressor signaling pathway: it is involved in the NF-kB pathway (Nuclear Factor kappa light- chain-enhancer of activated B cells) and in STAT3 (Signal Transducer and Activator of Transcription 3) of the JAK-STAT pathway. In this review, we summarize how the association between these different pathways reflects a dual role of TRIM8 in cancer as an oncogene or a tumor suppressor gene.

Knockdown of circ_0102273 inhibits the proliferation, metastasis and glycolysis of breast cancer through miR-1236-3p/PFKFB3 axis.

The key regulatory roles of circular RNAs (circRNAs) in human diseases have been demonstrated, including breast cancer (BC). The purpose of this study is to explore the role of circ_0102273, a newly discovered circRNA, in BC progression. The expression levels of circ_0102273, microRNA (miR)-1236-3p and 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3) were determined by quantitative real-time PCR. Cell proliferation, migration and invasion were measured using colony formation assay, EdU staining, wound healing assay and transwell assay. Glucose consumption, lactate production and ATP level were detected to evaluate cell glycolysis. The interaction between miR-1236-3p and circ_0102273 or PFKFB3 was confirmed by dual-luciferase reporter assay and RIP assay. Additionally, western blot analysis was utilized for measuring PFKFB3 protein expression. In-vivo experiments were performed to further explore the function of circ_0102273 in BC tumorigenesis. Our data showed that circ_0102273 was highly expressed in BC tumor tissues and cells, and its downregulation could inhibit BC cell proliferation, metastasis and glycolysis. MiR-1236-3p was confirmed to be sponged by circ_0102273, and its inhibitor could reverse the negative regulation of sh-circ_0102273 on BC cell proliferation, metastasis and glycolysis. PFKFB3 could be targeted by miR-1236-3p, and its expression could be positively regulated by circ_0102273. In addition, miR-1236-3p could suppress BC cell proliferation, metastasis and glycolysis, while this effect could be abolished by PFKFB3. Furthermore, circ_0102273 knockdown also had been discovered to reduce BC tumorigenesis in vivo. In summary, our research proposed that circ_0102273 might be a potential target for BC treatment, which could inhibit BC proliferation, metastasis and glycolysis through the miR-1236-3p/PFKFB3 axis.

Abstract P5-12-10: A commensal’s exopolysaccharide inhibits breast cancer proliferation in vitro but promotes tumor growth in vivo

Abstract Background: Recent decades have started to realize the importance of the microbiome in cancer initiation, progression and response to therapy. Recent findings suggest that both the local and distal microbiome may influence tumor growth. Although many studies focused on the gut microbiome, the breast itself also possesses a unique microbiome which differs between healthy and breast cancer patients, and between tumor subtypes. However, it is poorly understood whether these bacteria in the gut or the breast microenvironment may interact with breast cancer cells and if that interaction alters tumor growth. Bacteria produce metabolites and other signaling molecules to alter the host’s response. We have identified and purified an exopolysaccharide (EPS) produced by the commensal bacterium Bacillus subtilis, which was shown to act directly on the host’s innate immune cells to protect against various inflammatory diseases. This study aims to investigate if, and how the bacterial product (EPS) alters proliferation and tumor growth of breast cancer cells.Methods: Cell proliferation of bulk cells was conducted on PBS or EPS treated breast cancer cells (T47D, MDA-MB-468, MDA-MB-453, HCC1428, BT549, MDA-MB-231, ZR-75-30, and MCF-7) using trypan blue exclusion and the XTT assay. Flow cytometry was used to assess apoptosis with Annexin V, and cell cycle progression with propidium iodide. Cancer stem cell survival was assessed using the mammosphere forming assay. CRISPR/Cas9-mediated knockout of the Toll-like-receptor 4 (TLR4) was used to assess the requirement of TLR4 signaling on EPS-mediated phenotypes. RNA-sequencing was performed on both EPS-sensitive and resistant breast cancer cell lines after treatment with PBS or EPS for 20 hours. T47D xenografts studies were performed in vivo using EPS pretreatment and continual treatment via i.p. injection.Results: EPS inhibited proliferation of some breast cancer cell lines (T47D, MDA-MB-468, MDA-MB-453, HCC1428) in a concentration dependent manner while having little effect on others (BT549, MDA-MB-231, ZR-75-30, MCF7). EPS acted via distinct mechanisms depending on the cell line, increasing apoptosis in MDA-MB-468 cells while inducing G0/G1 cell cycle arrest in T47D cells. Although EPS directly inhibited bulk cell proliferation, the cancer stem cell population of T47D cells was increased by EPS. EPS is known to require TLR4 signaling to modulate immune cells. CRISPR/Cas9 knockout of TLR4 demonstrated that it was not required for EPS-mediated inhibition of T47D breast cancer cells, suggesting a novel mechanism of action in this cell line. RNA-sequence analysis showed that EPS altered interferon signaling and cell cycle progression pathways. Interferon signaling activates the STAT family of transcription factors, and western blots confirmed that 3h of EPS treatment induced STAT1 phosphorylation and p21 accumulation, indicating that EPS activated this pathway. Contrary to in vitro proliferation data, in vivo results showed that EPS-treated cells formed significantly larger tumors compared to PBS controls (273mg vs 59mg). The slope of tumor growth was also significantly faster in the EPS-treated group. Conclusions: These findings demonstrated the multifacet of EPS’s effect on breast cancer cells. EPS inhibits the proliferation of certain breast cancer cells in vitro, possibly via activation of STAT1 and p21 signaling, but also increases survival of cancer stem cells and promotes more aggressive tumor growth in vivo. This highlights the complexity of the influence of commensal bacteria on breast cancer growth, which can be highly context-dependent. Deeper understanding of this complex interplay between the host-microbe-tumor will be vital to the development of novel bacterial strategies in the future. Citation Format: Mai Rachel Nguyen, Katherine L Knight, Clodia Osipo. A commensal’s exopolysaccharide inhibits breast cancer proliferation in vitro but promotes tumor growth in vivo [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-12-10.

Baicalin-loaded folic acid-modified albumin nanoparticles (FA-BSANPs/BA) induce autophagy in MCF-7 cells via ROS-mediated p38 MAPK and Akt/mTOR pathway

BackgroundBreast cancer is the most frequently occurring cancer among women. Baicalin has been shown to inhibit breast cancer proliferation, but poor aqueous solubility and unknown mechanism of action limit its application. This study aimed to investigate the antiproliferative effects of baicalin-loaded folic acid-modified albumin nanoparticles (FA-BSANPs/BA) in breast cancer MCF-7 cells and its relationship with autophagy and ROS-mediated p38 MAPK and Akt/mTOR signaling pathways. Cell viability was detected by MTT assay. Flow cytometry and fluorescence microscopy were used to detect cell cycle, apoptosis and autophagy. Western blot was used to detect protein expression.ResultsCompared with the control and free baicalin groups, FA-BSANPs/BA inhibited viability of MCF-7 cells and increased cells in S phase, apoptotic bodies, pro-apoptotic proteins, autophagy markers and autophagosomes. These effects could be reversed when combined with the autophagy inhibitor 3-methyladenine. FA-BSANPs/BA increased the levels of phosphorylated p38 MAPK, inhibited the levels of phosphorylated Akt and mTOR, and increased the level of ROS in MCF-7 cells. The effects of FA-BSANPs/BA could be reversed or enhanced using inhibitors of Akt, mTOR, p38 MAPK and ROS scavengers.ConclusionsEncapsulation in folate albumin nanoparticles improved the antiproliferative activity of baicalin. FA-BSANPs/BA induced autophagy and apoptosis via ROS-mediated p38 MAPK and Akt/mTOR signaling pathways in human breast cancer cells.

Oxytocin Inhibits Breast Cancer Proliferation and Migration by Regulating the UlLK1/Autophagy Axis

Oxytocin Inhibits Breast Cancer Proliferation and Migration by Regulating the UlLK1/Autophagy Axis

CLDN6 Suppresses c–MYC–Mediated Aerobic Glycolysis to Inhibit Proliferation by TAZ in Breast Cancer

Claudin 6 (CLDN6) was found to be a breast cancer suppressor gene, which is lowly expressed in breast cancer and inhibits breast cancer cell proliferation upon overexpression. However, the mechanism by which CLDN6 inhibits breast cancer proliferation is unclear. Here, we investigated this issue and elucidated the molecular mechanisms by which CLDN6 inhibits breast cancer proliferation. First, we verified that CLDN6 was lowly expressed in breast cancer tissues and that patients with lower CLDN6 expression had a worse prognosis. Next, we confirmed that CLDN6 inhibited breast cancer proliferation through in vitro and in vivo experiments. As for the mechanism, we found that CLDN6 inhibited c–MYC–mediated aerobic glycolysis based on a metabolomic analysis of CLDN6 affecting cellular lactate levels. CLDN6 interacted with a transcriptional co–activator with PDZ-binding motif (TAZ) and reduced the level of TAZ, thereby suppressing c–MYC transcription, which led to a reduction in glucose uptake and lactate production. Considered together, our results suggested that CLDN6 suppressed c–MYC–mediated aerobic glycolysis to inhibit the proliferation of breast cancer by TAZ, which indicated that CLDN6 acted as a novel regulator of aerobic glycolysis and provided a theoretical basis for CLDN6 as a biomarker of progression in breast cancer.