Human Breast Cancer Metastasis Research Articles

Abstract 5417: PHGDH expression level impacts tumorigenesis and metastasis in human breast cancer

Abstract Background: Phosphoglycerate dehydrogenase (PHGDH) is a metabolic enzyme, which is associated with the first step of serine synthesis. The gene encoding this enzyme is often elevated in some types of human cancer, including breast cancer. There are some researches that High-PHGDH expression promotes cancer cell proliferation and tumorigenesis. However, latest study showed that although breast tumors with high expression levels of PHGDH had more possibility to undergo primary-tumor growth, were less likely to metastasize than tumors with low expression of PHGDH by using mouse cell derived mouse models and PDX models. Nevertheless, the applicability of these outcomes to human breast cancer cell lines remains uncertain. Methods: The survival analysis according to PHGDH mRNA expression was analyzed in METABRIC datasets of breast cancer and the whole-transcriptome sequencing data of 120 breast cancer patients. To investigate the effect of PHGDH in human TNBC cell lines, PHGDH overexpressing MDA-MB-231 cell lines and PHGDH knockdown MDA-MB-468 cell lines were established. Subsequent functional experiments were performed to explore the influence of PHGDH on breast cancer tumorigenesis and metastasis. Results: In the analysis using METABRIC datasets, overall survival and disease-free survival were reduced in patients with high PHGDH expression and basal type breast cancer showed the highest mRNA level of PHGDH. Using whole-transcriptome sequencing data of 120 breast cancer patients, we also found PHGDH expression level was higher in cancer tissue(n=120) than normal tissue(n=90). In particular, triple-negative breast cancer indicated higher PHGDH level than luminal type breast cancer. We also used this data to perform analysis of overall survival, disease-free survival, metastasis free survival of non-TNBC patient and it resulted in reducing survival rate when patient showed high-PHGDH expression. However, TNBC patients demonstrated diametrical results in the identical analysis. We examined the impact of PHGDH overexpression in MDA-MB-231 cells and PHGDH knockdown in MDA-MB-468 cells, observing increased proliferation and decreased migration in breast cancer cells with elevated PHGDH levels. Conversely, PHGDH knockdown exhibited opposing effects. Subsequently analysis of markers associated with epithelial-mesenchymal transition revealed a correlation with PHGDH expression. Conclusions: Our data suggest that a potential role for PHGDH in breast cancer as a marker of reduced survival in triple-negative breast cancer, and as a regulator of cancer cell proliferation and metastasis. Citation Format: Jihong Baik, Juhee Kim, Sangeun Lee, Ayoung Park, Kyoungseob Shin, Sunghoon Kwon, Hanbyoel Lee, Wonshik Han. PHGDH expression level impacts tumorigenesis and metastasis in human breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5417.

Abstract 6630: Non-cell-autonomous cancer progression from chromosomal instability

Abstract Chromosomal instability (CIN) is a driver of cancer metastasis, yet the extent to which this effect depends on the immune system remains unknown. Using ContactTracing—a newly developed, validated and benchmarked tool to infer the nature and conditional dependence of cell-cell interactions from single-cell transcriptomic data—we show that CIN-induced chronic activation of the cGAS-STING pathway promotes downstream signal re-wiring in cancer cells, leading to a pro-metastatic tumor microenvironment. This re-wiring is manifested by type I interferon tachyphylaxis selectively downstream of STING and a corresponding increase in cancer cell-derived endoplasmic reticulum (ER) stress response. Reversal of CIN, depletion of cancer cell STING or inhibition of ER stress response signaling abrogates CIN-dependent effects on the tumor microenvironment and suppresses metastasis in immune competent, but not severely immune compromised, settings. Treatment with STING inhibitors reduces CIN-driven metastasis in melanoma, breast and colorectal cancers in a manner dependent on tumor cell-intrinsic STING. Finally, we show that CIN and pervasive cGAS activation in micronuclei are associated with ER stress signaling, immune suppression and metastasis in human triple-negative breast cancer, highlighting a viable strategy to identify and therapeutically intervene in tumors spurred by CIN-induced inflammation. Citation Format: Jun Li, Melissa Hubisz, Ethan Earlie, Mercedes Duran, Christy Hong, Austin Varela, Emanuele Lettera, Matthew Deyell, Bernardo Tavora, Jonathan Havel, Phyu Su, Amit Dipak Amin, Karolina Budre, Erina Kamiya, Julie-Ann Cavallo, Christopher Garris, Simon Powell, Jorge Reis-Filho, Hannah Wen, Sarah Bettigole, Atif Khan, Benjamin Izar, Eileen Parkes, Ashley Laughney, Samuel Bakhoum. Non-cell-autonomous cancer progression from chromosomal instability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6630.

Abstract 4129: Mitochondria-targeted antioxidant MitoQ inhibits human breast cancer metastasis in mice

Abstract In oncology, the occurrence of distant metastases often marks the transition from curative to palliative care. Such outcome is highly predictable for triple-negative and HER2-positive breast cancer patients, even if tumors are detected early, and there is no treatment to prevent metastasis. Here, considering that mitochondria are bioenergetic sensors of the tumor microenvironment, we report in preclinical mouse models that human breast cancer relapse is not a fatality: local recurrence and metastatic dissemination can be prevented by MitoQ, a mitochondria-targeted antioxidant that already underwent Phase I safety and Phase II efficacy trials in humans for pathologies other than cancer. Metastatic prevention was confirmed in the MMTV-PyMT model of spontaneously metastatic mouse breast cancer. After oral delivery, MitoQ was effective at nanomolar concentrations at which nonmalignant cells were spared. In anticipation of future clinical trials, a robust signature of the response to MitoQ was defined, applicable to bulk primary tumor biopsies. Citation Format: Tania Capeloa, Pierre Sonveaux. Mitochondria-targeted antioxidant MitoQ inhibits human breast cancer metastasis in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4129.

Antibodies toward Na+,HCO3--cotransporter NBCn1/SLC4A7 block net acid extrusion and cause pH-dependent growth inhibition and apoptosis in breast cancer.

Na+,HCO3--cotransporter NBCn1/Slc4a7 accelerates murine breast carcinogenesis. Lack of specific pharmacological tools previously restricted therapeutic targeting of NBCn1 and identification of NBCn1-dependent functions in human breast cancer. We develop extracellularly-targeted anti-NBCn1 antibodies, screen for functional activity on cells, and evaluate (a) mechanisms of intracellular pH regulation in human primary breast carcinomas, (b) proliferation, cell death, and tumor growth consequences of NBCn1 in triple-negative breast cancer, and (c) association of NBCn1-mediated Na+,HCO3--cotransport with human breast cancer metastasis. We identify high-affinity (KD ≈ 0.14 nM) anti-NBCn1 antibodies that block human NBCn1-mediated Na+,HCO3--cotransport in cells, without cross-reactivity towards human NBCe1 or murine NBCn1. These anti-NBCn1 antibodies abolish Na+,HCO3--cotransport activity in freshly isolated primary organoids from human breast carcinomas and lower net acid extrusion effectively in primary breast cancer tissue from patients with macrometastases in axillary lymph nodes. Inhibitory anti-NBCn1 antibodies decelerate tumor growth in vivo by ~50% in a patient-derived xenograft model of triple-negative breast cancer and pH-dependently reduce colony formation, cause G2/M-phase cell cycle accumulation, and increase apoptosis of metastatic triple-negative breast cancer cells in vitro. Inhibitory anti-NBCn1 antibodies block net acid extrusion in human breast cancer tissue, particularly from patients with disseminated disease, and pH-dependently limit triple-negative breast cancer growth.

Retraction: Diallyl Disulfide Suppresses SRC/Ras/ERK Signaling-Mediated Proliferation and Metastasis in Human Breast Cancer by Up-Regulating miR-34a

Retraction: Diallyl Disulfide Suppresses SRC/Ras/ERK Signaling-Mediated Proliferation and Metastasis in Human Breast Cancer by Up-Regulating miR-34a

A PERK-Specific Inhibitor Blocks Metastatic Progression by Limiting Integrated Stress Response-Dependent Survival of Quiescent Cancer Cells.

The integrated stress response (ISR) kinase PERK serves as a survival factor for both proliferative and dormant cancer cells. We aim to validate PERK inhibition as a new strategy to specifically eliminate solitary disseminated cancer cells (DCC) in secondary sites that eventually reawake and originate metastasis. A novel clinical-grade PERK inhibitor (HC4) was tested in mouse syngeneic and PDX models that present quiescent/dormant DCCs or growth-arrested cancer cells in micro-metastatic lesions that upregulate ISR. HC4 significantly blocks metastasis, by killing quiescent/slow-cycling ISRhigh, but not proliferative ISRlow DCCs. HC4 blocked expansion of established micro-metastasis that contained ISRhigh slow-cycling cells. Single-cell gene expression profiling and imaging revealed that a significant proportion of solitary DCCs in lungs were indeed dormant and displayed an unresolved ER stress as revealed by high expression of a PERK-regulated signature. In human breast cancer metastasis biopsies, GADD34 expression (PERK-regulated gene) and quiescence were positively correlated. HC4 effectively eradicated dormant bone marrow DCCs, which usually persist after rounds of therapies. Importantly, treatment with CDK4/6 inhibitors (to force a quiescent state) followed by HC4 further reduced metastatic burden. In HNSCC and HER2+ cancers HC4 caused cell death in dormant DCCs. In HER2+ tumors, PERK inhibition caused killing by reducing HER2 activity because of sub-optimal HER2 trafficking and phosphorylation in response to EGF. Our data identify PERK as a unique vulnerability in quiescent or slow-cycling ISRhigh DCCs. The use of PERK inhibitors may allow targeting of pre-existing or therapy-induced growth arrested "persister" cells that escape anti-proliferative therapies.

Non-cell-autonomous cancer progression from chromosomal instability

Chromosomal instability (CIN) is a driver of cancer metastasis1–4, yet the extent to which this effect depends on the immune system remains unknown. Using ContactTracing—a newly developed, validated and benchmarked tool to infer the nature and conditional dependence of cell–cell interactions from single-cell transcriptomic data—we show that CIN-induced chronic activation of the cGAS–STING pathway promotes downstream signal re-wiring in cancer cells, leading to a pro-metastatic tumour microenvironment. This re-wiring is manifested by type I interferon tachyphylaxis selectively downstream of STING and a corresponding increase in cancer cell-derived endoplasmic reticulum (ER) stress response. Reversal of CIN, depletion of cancer cell STING or inhibition of ER stress response signalling abrogates CIN-dependent effects on the tumour microenvironment and suppresses metastasis in immune competent, but not severely immune compromised, settings. Treatment with STING inhibitors reduces CIN-driven metastasis in melanoma, breast and colorectal cancers in a manner dependent on tumour cell-intrinsic STING. Finally, we show that CIN and pervasive cGAS activation in micronuclei are associated with ER stress signalling, immune suppression and metastasis in human triple-negative breast cancer, highlighting a viable strategy to identify and therapeutically intervene in tumours spurred by CIN-induced inflammation.

Eta polycaprolactone (ε-PCL) implants appear to cause a partial differentiation of breast cancer lung metastasis in a murine model

BackgroundCells in every epithelium can be roughly divided in three compartments: stem cell (SC) compartment, transient amplifying cell (TA) compartment and terminally differentiated (TD) compartment. Maturation of stem cells is characterized by epithelial stromal interaction and sequential maturational movement of stem cell’s progeny through those compartments. In this work we hypothesize that providing an artificial stroma, which murine breast cancer metastatic cells can infiltrate, will induce their differentiation.MethodsBALB/c female mice were injected with 106 isogenic 4T1 breast cancer cells labeled with GFP. After 20 days primary tumors were removed, and artificial ε-PCL implants were implanted on the contralateral side. After 10 more days mice were sacrificed and implants along with lung tissue were harvested. Mice were divided in four groups: tumor removal with sham implantation surgery (n = 5), tumor removal with ε-PCL implant (n = 5), tumor removal with VEGF enriched ε-PCL implant (n = 7) and mice without tumor with VEGF enriched ε-PCL implant (n = 3). Differentiational status of GFP + cells was assessed by Ki67 and activated caspase 3 expression, thus dividing the population in SC like cells (Ki67+/dim aCasp3−), TA like cells (Ki67+/dim aCasp3+/dim) and TD like cells (Ki67− aCasp3+/dim) on flow cytometry.ResultsLung metastatic load was reduced by 33% in mice with simple ε-PCL implant when compared to tumor bearing group with no implant. Mice with VEGF enriched implants had 108% increase in lung metastatic load in comparison to tumor bearing mice with no implants. Likewise, amount of GFP + cells was higher in simple ε-PCL implant in comparison to VEGF enriched implants. Differentiation-wise, process of metastasizing to lungs reduces the average fraction of SC like cells when compared to primary tumor. This effect is made more uniform by both kinds of ε-PCL implants. The opposite process is mirrored in TA like cells compartment when it comes to averages. Effects of both types of implants on TD like cells were negligible. Furthermore, if gene expression signatures that mimic tissue compartments are analyzed in human breast cancer metastases, it turns out that TA signature is associated with increased survival probability.Conclusionε-PCL implants without VEGF can reduce metastatic loads in lungs, after primary tumor removal. Both types of implants cause lung metastasis differentiation by shifting cancer cells from SC to TA compartment, leaving the TD compartment unaffected.

Chronic Exposure to Low Levels of Parabens Increases Mammary Cancer Growth and Metastasis in Mice.

Methylparaben (MP) and propylparaben (PP) are commonly used as food, cosmetic, and drug preservatives. These parabens are detected in the majority of US women and children, bind and activate estrogen receptors (ER), and stimulate mammary tumor cell growth and invasion in vitro. Hemizygous B6.FVB-Tg (MMTV-PyVT)634Mul/LellJ female mice (n = 20/treatment) were exposed to MP or PP at levels within the US Food and Drug Administration's "human acceptable daily intake." These paraben-exposed mice had increased mammary tumor volume compared with control mice (P < 0.001) and a 28% and 91% increase in the number of pulmonary metastases per week compared with the control mice, respectively (P < 0.0001). MP and PP caused differential expression of 288 and 412 mammary tumor genes, respectively (false discovery rate < 0.05), a subset of which has been associated with human breast cancer metastasis. Molecular docking and luciferase reporter studies affirmed that MP and PP bound and activated human ER, and RNA-sequencing revealed increased ER expression in mammary tumors among paraben-exposed mice. However, ER signaling was not enriched in mammary tumors. Instead, both parabens strongly impaired tumor RNA metabolism (eg, ribosome, spliceosome), as evident from enriched KEGG pathway analysis of differential mammary tumor gene expression common to both paraben treatments (MP, P < 0.001; PP, P < 0.01). Indeed, mammary tumors from PP-exposed mice had an increased retention of introns (P < 0.05). Our data suggest that parabens cause substantial mammary cancer metastasis in mice as a function of their increasing alkyl chain length and highlight the emerging role of aberrant spliceosome activity in breast cancer metastasis.

Co-expression of Matrix Metalloproteinase 9 (MMP9) and Motility-related Protein-1 (MRP-1/CD9) in Human Breast Cancer

Background: Controversial evidence exists regarding the metastasis-suppressor or promoting activity of motility-related protein-1 (MRP-1/CD9) in breast cancer (BC). Objectives: we aimed at investigating the possible correlation of CD9 with a metastasis marker matrix metalloproteinase 9 (MMP9) in human BC tissues. Methods: A total of 19 BC and 5 normal breast tissues were analyzed. The mRNA expression of CD9 and MMP9 was measured by quantitative PCR. The correlation of genes’ expression with each other and clinicopathological features (i. e. tumor pathology, grade, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), P53, and KI67) was tested by relevant statistical analysis methods. Results: There was no significant difference between patients with BC and the control group regarding the expression of MMP9 (P = 0.394) and CD9 (P = 0.887). A significant strong positive correlation was observed between CD9 and MMP-9 expressions (r = 0.761 and P = 0.0002). The MMP9 expression was significantly higher in ER or PR positive compared to ER or PR negative tumors (P = 0.046). Conclusions: Given the strong correlation with MMP9, it seems that CD9 might have a role in metastasis in human BC. However, much more studies are required to further support this hypothesis.

Matrix metalloproteinase 2 is a target of the RAN-GTP pathway and mediates migration, invasion and metastasis in human breast cancer

RAS-related nuclear protein(RAN) is a nuclear shuttle and normally regulates events in the cell cycle. When overexpressed in cultured cells, it causes increases in cell migration/invasion in vitro and its overexpression is associated with early breast cancer patient deaths in vivo. However, the underlying mechanism is unknown. The effect of RAN overexpression on potential targets MMP2, ATF3, CXCR3 was investigated by Real-Time PCR/Western blots in the triple receptor negative breast cancer(TRNBC) cell line MDA-MB231 and consequent biological effects were measured by cell adhesion, cell migration and cell invasion assays. Results showed that knockdown of RAN lead to a reduction of MMP2 and its potential regulators ATF3 and CXCR3. Moreover, knockdown of ATF3 or CXCR3 downregulated MMP2 without affecting RAN, indicating that RAN regulates MMP2 through ATF3 and CXCR3. Knockdown of RAN and MMP2 reduced cell adhesion, cell migration and cell growth in agar, whilst overexpression of MMP2 reversed the knockdown of RAN. Furthermore, immunohistochemical staining for RAN and MMP2 are positively associated with each other in the same tumour and separately with patient survival times in breast cancer specimens, suggesting that a high level of RAN may be a pre-requisite for MMP2 overexpression and metastasis. Moreover, positive immunohistochemical staining for both RAN and MMP-2 reduces further patient survival times over that for either protein separately. Our results suggest that MMP2 expression can stratify progression of breast cancers with a high and low incidence of RAN, both RAN and MMP2 in combination can be used for a more accurate patient prognosis. Simple summaryRan is an important regulator of normal cell growth and behaviour. We have established in cell line models of breast cancer (BC) a molecular pathway between RAN and its protein-degrading effector MMP-2 and properties related to metastasis in culture. Using immunohistochemistry (IHC) staining of primary BCs, we have shown that RAN and MMP-2 are on their own significantly associated with patient demise from metastatic BC. Moreover, when staining for MMP-2 is added to that for RAN in the primary tumours, there is a significant decrease in patient survival time over that for either protein alone. Thus a combination of staining for RAN and MMP2 is an excellent marker for poor prognosis in breast cancer.

Assessment of MRI to estimate metastatic dissemination risk and prometastatic effects of chemotherapy

Metastatic dissemination in breast cancer is regulated by specialized intravasation sites called “tumor microenvironment of metastasis” (TMEM) doorways, composed of a tumor cell expressing the actin-regulatory protein Mena, a perivascular macrophage, and an endothelial cell, all in stable physical contact. High TMEM doorway number is associated with an increased risk of distant metastasis in human breast cancer and mouse models of breast carcinoma. Here, we developed a novel magnetic resonance imaging (MRI) methodology, called TMEM Activity-MRI, to detect TMEM-associated vascular openings that serve as the portal of entry for cancer cell intravasation and metastatic dissemination. We demonstrate that TMEM Activity-MRI correlates with primary tumor TMEM doorway counts in both breast cancer patients and mouse models, including MMTV-PyMT and patient-derived xenograft models. In addition, TMEM Activity-MRI is reduced in mouse models upon treatment with rebastinib, a specific and potent TMEM doorway inhibitor. TMEM Activity-MRI is an assay that specifically measures TMEM-associated vascular opening (TAVO) events in the tumor microenvironment, and as such, can be utilized in mechanistic studies investigating molecular pathways of cancer cell dissemination and metastasis. Finally, we demonstrate that TMEM Activity-MRI increases upon treatment with paclitaxel in mouse models, consistent with prior observations that chemotherapy enhances TMEM doorway assembly and activity in human breast cancer. Our findings suggest that TMEM Activity-MRI is a promising precision medicine tool for localized breast cancer that could be used as a non-invasive test to determine metastatic risk and serve as an intermediate pharmacodynamic biomarker to monitor therapeutic response to agents that block TMEM doorway-mediated dissemination.

Graph attention network for link prediction of gene regulations from single-cell RNA-sequencing data.

Single-cell RNA sequencing (scRNA-seq) data provides unprecedented opportunities to reconstruct gene regulatory networks (GRNs) at fine-grained resolution. Numerous unsupervised or self-supervised models have been proposed to infer GRN from bulk RNA-seq data, but few of them are appropriate for scRNA-seq data under the circumstance of low signal-to-noise ratio and dropout. Fortunately, the surging of TF-DNA binding data (e.g. ChIP-seq) makes supervised GRN inference possible. We regard supervised GRN inference as a graph-based link prediction problem that expects to learn gene low-dimensional vectorized representations to predict potential regulatory interactions. In this paper, we present GENELink to infer latent interactions between transcription factors (TFs) and target genes in GRN using graph attention network. GENELink projects the single-cell gene expression with observed TF-gene pairs to a low-dimensional space. Then, the specific gene representations are learned to serve for downstream similarity measurement or causal inference of pairwise genes by optimizing the embedding space. Compared to eight existing GRN reconstruction methods, GENELink achieves comparable or better performance on seven scRNA-seq datasets with four types of ground-truth networks. We further apply GENELink on scRNA-seq of human breast cancer metastasis and reveal regulatory heterogeneity of Notch and Wnt signalling pathways between primary tumour and lung metastasis. Moreover, the ontology enrichment results of unique lung metastasis GRN indicate that mitochondrial oxidative phosphorylation (OXPHOS) is functionally important during the seeding step of the cancer metastatic cascade, which is validated by pharmacological assays. The code and data are available at https://github.com/zpliulab/GENELink. Supplementary data are available at Bioinformatics online.

Long Non-Coding RNA LINC00052 Targets miR-548p/Notch2/Pyk2 to Modulate Tumor Budding and Metastasis of Human Breast Cancer.

Abnormal expression of long non-coding RNAs (lncRNAs) is involved in many pathological processes of cancers. However, the role of lncRNA LINC00052 in breast cancer progression is still unclear. Here, LINC00052 expression was detected by in situ hybridization and quantitative real-time PCR assays. Cell Counting Kit-8, wound healing, and transwell assays were used to investigate changes in the proliferation, migration, and invasion of breast cancer cells. MiR-548p was found associated with LINC00052 or Notch2 by RNA pull-down, dual-luciferase reporter, and qRT-PCR assays. The effect of LINC00052 on lung metastasis was explored through in vivo experiments. High LINC00052 expression was observed in breast cancer tissues and cells. LINC00052 silencing inhibited the proliferation, migration, and invasion of MCF7 cells, and LINC00052 overexpression produced the opposite results. MiR-548p, a target gene of LINC00052, partially rescued the effects of LINC00052 on proliferation, migration, and invasion of MCF7. Notch2 was the target of miR-548p and LINC00052 could promote Notch2 expression. Moreover, the phosphorylation of proline-rich tyrosine kinase 2 (Pyk2), a downstream factor of Notch2, was increased by LINC00052, and a Pyk2 mutant could inhibit the cell migration and invasion induced by LINC00052 overexpression in MDA-MB-468 cells, which was similar to the function of the miR-548p mimic. We further demonstrated that LINC00052 exacerbated the metastases of breast cancer cells in vivo. Our research demonstrated that LINC00052 is highly expressed in breast cancer and promotes breast cancer proliferation, migration, and invasion via the miR-548p/Notch2/Pyk2 axis. LINC00052 could serve as a potential therapeutic target for breast cancer.

Analysis of the Clinical Molecular Characteristics and Neoadjuvant Chemotherapy Response in Patients with Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer and Axillary Lymph Node Metastasis

Objective: This study aimed to investigate the clinical molecular characteristics in patients with human epidermal growth factor receptor 2 (HER2)-negative breast cancer and axillary lymph node metastasis and explored the related factors of the neoadjuvant chemotherapy (NAC) response. Methods: The data of 185 patients with HER2-negative breast cancer and axillary lymph node metastasis who were treated in the Department of Breast Center of the Affiliated Hospital of Qingdao University from July 2017 to July 2021 were retrospectively analyzed. The clinical features and the related factors for the responses of the primary tumor and axillary lymph node metastasis to NAC were analyzed. Statistical analysis was conducted using the SPSS 26.0 statistical software. Univariate analysis was conducted using the χ2 test, and multivariate analysis was conducted using logistic regression analysis. Results: The differences in estrogen receptor (ER), progesterone receptor (PR), and Ki67 among the three HER2-negative subgroups (the immunohistochemistry (IHC)0 group, IHC1+ group, and IHC2+/in situ hybridization– group) were statistically significant (p &lt; 0.05). Univariate analysis revealed that the differences in the tumor stage, ER, PR, and Ki67 among the groups based on the response of the primary tumor to NAC were statistically significant (p &lt; 0.05), and the differences in ER, PR, and Ki67 among the groups based on the response of axillary lymph node metastasis to NAC were statistically significant (p &lt; 0.05). Multivariate analysis revealed that the difference in Ki67 among the groups based on the response of axillary lymph node metastasis to NAC was statistically significant (p &lt; 0.05). Conclusions: When the expression level of HER2-negative IHC increases, the positive rates of ER and PR increase. A smaller tumor, negative ER, negative PR, and a Ki67 level &gt;30% indicate a good effect of NAC for primary tumors. Negative ER, negative PR, and a Ki67 level &gt;30% indicate a good effect of NAC for axillary lymph node metastasis. Therefore, Ki67 may be an independent factor affecting the efficacy of NAC for axillary lymph node metastasis.

Isoforms of Neuropilin-2 Denote Unique Tumor-Associated Macrophages in Breast Cancer.

Tumor-associated macrophages (TAMs) exert profound influence over breast cancer progression, promoting immunosuppression, angiogenesis, and metastasis. Neuropilin-2 (NRP2), consisting of the NRP2a and NRP2b isoforms, is a co-receptor for heparin-binding growth factors including VEGF-C and Class 3 Semaphorins. Selective upregulation in response to environmental stimuli and independent signaling pathways endow the NRP2 isoforms with unique functionality, with NRP2b promoting increased Akt signaling via receptor tyrosine kinases including VEGFRs, MET, and PDGFR. Although NRP2 has been shown to regulate macrophage/TAM biology, the role of the individual NRP2a/NRP2b isoforms in TAMs has yet to be evaluated. Using transcriptional profiling and spectral flow cytometry, we show that NRP2 isoform expression was significantly higher in TAMs from murine mammary tumors. NRP2a/NRP2b levels in human breast cancer metastasis were dependent upon the anatomic location of the tumor and significantly correlated with TAM infiltration in both primary and metastatic breast cancers. We define distinct phenotypes of NRP2 isoform-expressing TAMs in mouse models of breast cancer and within malignant pleural effusions from breast cancer patients which were exclusive of neuropilin-1 expression. Genetic depletion of either NRP2 isoform in macrophages resulted in a dramatic reduction of LPS-induced IL-10 production, defects in phagosomal processing of apoptotic breast cancer cells, and increase in cancer cell migration following co-culture. By contrast, depletion of NRP2b, but not NRP2a, inhibited production of IL-6. These results suggest that NRP2 isoforms regulate both shared and unique functionality in macrophages and are associated with distinct TAM subsets in breast cancer.

ECSIT inhibits cell death to increase tumor progression and metastasis via p53 in human breast cancer

BackgroundCurrently, breast cancer has surpassed lung cancer as the most common cancer and the molecular mechanism involved in tumor initiation and metastasis was unclear. Therefore, it is necessary to advance our understanding of tumor progression and metastasis and find out new targets. An evolutionarily conserved signaling intermediate in Toll pathways (ECSIT) is involved in the innate immune response and has been shown as tumor suppressors by downregulating nuclear factor-kappa B (NF-κB) pathway. However, the role of ECSIT in the progression and metastasis of human breast cancer remains unknown.MethodsWe overexpressed ECSIT by transfection of a eukaryotic expression plasmid and constructed a breast cancer cell line with stable knockdown of ECSIT by short hairpin RNA. And we silenced p53 through small interfering RNA. In vivo, we replicated a xenograft mouse model in nude mice. The effects on the proliferation, viability, migration and invasion were studied by 5-ethynyl-2-deoxyuridine, cell counting Kit-8, wound healing and invasion assays. Propidium iodide/Hoechst 33342 staining and cleaved-caspase-3 staining were used to verify cell death. Western blot, immunohistochemistry (IHC) and histological analyses were used to explore the regulatory mechanism of tumor changes.ResultsWe reported the association of ECSIT with human breast cancer. In vitro assays demonstrated that ECSIT promoted MDA-MB-231 cell proliferation (by 66.15%), migration and invasion (by 58.29%). Knockdown of ECSIT significantly decreased cell proliferation (by 38.33%), viability, migration and invasion (by 62.37%), and increased cell death (by 41.1%). The in vivo results further confirmed that knockdown of ECSIT depressed tumorigenicity (by 29.46%) and metastasis (by 76.19%). Mechanistic investigations indicated that silencing of ECSIT could decrease the expression of p65 (by 46.05%), a subunit of NF-κB, and increase p53 protein expression in nuclei (by 89.53%). Moreover, we demonstrated that knockdown of p53 abolished the protection against cell death, which indicated that ECSIT might be involved in breast cancer progression through a p53-dependent pathway.ConclusionsOur studies provide new insight into the mechanisms underlying the role of ECSIT as well as a novel target for human breast cancer, and the development of novel ECSIT inhibitors is important for the management of TNBC.

Suppression of SIN3A by miR-183 Promotes Breast Cancer Metastasis.

SIN3A expression is decreased in metastatic breast cancer in part due to miR-183.

Abstract P1-19-02: Repurposing the FOXO4 senolytic against triple-negative breast cancer

Abstract Metastatic breast cancer is the second most common cause of cancer-related death in women. Triple Negative Breast Cancer (TNBC) has tan especially poor prognosis partly due to these tumors lacking relevant molecular targets. The most commonly mutated gene in TNBC is the tumor suppressor TP53. Mostly, p53 mutations give rise to stably expressed proteins with tumor promoting functions. Therefore, there is an urgent need for therapeutics that can target p53-mutated TNBCs. Here we show that an anti-senescence compound can target metastatic cancers. We found that, in TNBCs, mutant p53 attained a distinctive conformation that has novel oncogenic roles through binding to the transcription factor Forkhead box O (FOXO) 4 sequestered within promyelocytic leukemia (PML) foci. Since these nuclear structures are specific to senescent cells, we tested the senolytic FOXO4 peptide. In cytotoxicity experiments, we found this compound to target TNBCs specifically over other breast cancer subtypes. Most importantly, these compounds decrease metastatic burden in the most commonly-used mouse model for human breast cancer metastasis. In summary, our results demonstrate that mutant p53-driven cancers presented senescent cell-specific characteristics that makes them a great candidate for the FOXO4-directed anti-senescence therapy. We expect that creative repurposing of senolytics to translate to other types of cancer that are driven by mutant p53. Citation Format: Diana Putavet, Marjolein Baar, Tao Shi, Johannes Lehmann, Tim Leyten, Esmee Bouma, Antoine Khalil, Harm-Jan Vos, Boudewijn Burgering, Tobias Dansen, Patrick Derksen, Peter de Keizer. Repurposing the FOXO4 senolytic against triple-negative breast cancer [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 P1-19-02.

Disruption of Prostaglandin E2 Signaling in Cancer-Associated Fibroblasts Limits Mammary Carcinoma Growth but Promotes Metastasis.

The inflammatory lipid prostaglandin E2 suppresses cancer-associated fibroblast expansion and activation to limit primary mammary tumor growth while promoting metastasis.