A cuproptosis-based nanomedicine suppresses triple negative breast cancers by regulating tumor microenvironment and eliminating cancer stem cells.

Cuproptosis is a new kind of cell death that depends on delivering copper ions into mitochondria to trigger the aggradation of tricarboxylic acid (TCA) cycle proteins and has been observed in various cancer cells. However, whether cuproptosis occurs in cancer stem cells (CSCs) is unexplored thus far, and CSCs often reside in a hypoxic tumor microenvironment (TME) of triple negative breast cancers (TNBC), which suppresses the expression of the cuproptosis protein FDX1, thereby diminishing anticancer efficacy of cuproptosis. Herein, a ROS-responsive active targeting cuproptosis-based nanomedicine CuET@PHF is developed by stabilizing copper ionophores CuET nanocrystals with polydopamine and hydroxyethyl starch to eradicate CSCs. By taking advantage of the photothermal effects of CuET@PHF, tumor hypoxia is overcome via tumor mechanics normalization, thereby leading to enhanced cuproptosis and immunogenic cell death in 4T1 CSCs. As a result, the integration of CuET@PHF and mild photothermal therapy not only significantly suppresses tumor growth but also effectively inhibits tumor recurrence and distant metastasis by eliminating CSCs and augmenting antitumor immune responses. This study presents the first evidence of cuproptosis in CSCs, reveals that disrupting hypoxia augments cuproptosis cancer therapy, and establishes a paradigm for potent cancer therapy by simultaneously eliminating CSCs and boosting antitumor immunity.

Photoswitchable dynamics and RNAi synergist with tailored interface and controlled release reprogramming tumor immunosuppressive niche.

Immunosuppressive tumor microenvironment (ITM) severely limited the efficacy of immunotherapy against triple-negative breast cancer (TNBC). Herein, Apt-LPR, a light-activatable photodynamic therapy (PDT)/RNAi immune synergy-enhancer was constructed by co-loading miR-34a and photosensitizers in cationic liposomes (in phase III clinical trial). Interestingly, the introduction of tumor-specific aptamers creates a special "Liposome-Aptamer-Target" interface, where the aptamers are initially in a "lying down" state but transform to "standing up" after target binding. The interfacing mechanism was elaborately revealed by computational and practical experiments. This unique interface endowed Apt-LPR with neutralized surface potential of cationic liposomes to reduce non-specific cytotoxicity, enhanced DNase resistance to protect aptamers, and preserved target-binding ability for selective drug delivery. Upon near-infrared irradiation, the generated reactive oxygen species would oxidize unsaturated phospholipids to destabilize both liposomes and lysosomes, realizing stepwise lysosomal escape of miR-34a for tumor cell apoptosis and downregulation of PD-L1 to suppress immune escape. Together, tumor-associated antigens released from PDT-damaged mitochondria and endoplasmic reticulum could activate the suppressive immune cells to establish an "immune hot" milieu. The collaborative immune-enhancing strategy effectively aroused systemic antitumor immunity and inhibited primary and distal tumor progression as well as lung metastasis in 4T1 xenografted mouse models. The photo-controlled drug release and specific tumor-targeting capabilities of Apt-LPR were also visualized in MDA-MB-231 xenografted zebrafish models. Therefore, this photoswitchable PDT/RNAi immune stimulator offered a powerful approach to reprogramming ITM and reinforcing cancer immunotherapy efficacy.

Nanodynamo quantifies subcellular RNA dynamics revealing extensive coupling between steps of the RNA life cycle.

The coordinated action of transcriptional and post-transcriptional machineries shapes gene expression programs at steady state and determines their concerted response to perturbations. We have developed Nanodynamo, an experimental and computational workflow for quantifying the kinetic rates of nuclear and cytoplasmic steps of the RNA life cycle. Nanodynamo is based on mathematical modelling following sequencing of native RNA from cellular fractions and polysomes. We have applied this workflow to triple-negative breast cancer cells, revealing widespread post-transcriptional RNA processing that is mutually exclusive with its co-transcriptional counterpart. We used Nanodynamo to unravel the coupling between transcription, processing, export, decay and translation machineries. We have identified a number of coupling interactions within and between the nucleus and cytoplasm that largely contribute to coordinating how cells respond to perturbations that affect gene expression programs. Nanodynamo will be instrumental in unravelling the determinants and regulatory processes involved in the coordination of gene expression responses.

TBC1 domain-containing proteins are frequently involved in triple-negative breast cancers in connection with the induction of a glycolytic phenotype.

Metabolic plasticity is a hallmark of cancer, and metabolic alterations represent a promising therapeutic target. Since cellular metabolism is controlled by membrane traffic at multiple levels, we investigated the involvement of TBC1 domain-containing proteins (TBC1Ds) in the regulation of cancer metabolism. These proteins are characterized by the presence of a RAB-GAP domain, the TBC1 domain, and typically function as attenuators of RABs, the master switches of membrane traffic. However, a number of TBC1Ds harbor mutations in their catalytic residues, predicting biological functions different from direct regulation of RAB activities. Herein, we report that several genes encoding for TBC1Ds are expressed at higher levels in triple-negative breast cancers (TNBC) vs. other subtypes of breast cancers (BC), and predict prognosis. Orthogonal transcriptomics/metabolomics analysis revealed that the expression of prognostic TBC1Ds correlates with elevated glycolytic metabolism in BC cell lines. In-depth investigations of the three top hits from the previous analyses (TBC1D31, TBC1D22B and TBC1D7) revealed that their elevated expression is causal in determining a glycolytic phenotype in TNBC cell lines. We further showed that the impact of TBC1D7 on glycolytic metabolism of BC cells is independent of its known participation in the TSC1/TSC2 complex and consequent downregulation of mTORC1 activity. Since TBC1D7 behaves as an independent prognostic biomarker in TNBC, it could be used to distinguish good prognosis patients who could be spared aggressive therapy from those with a poor prognosis who might benefit from anti-glycolytic targeted therapies. Together, our results highlight how TBC1Ds connect disease aggressiveness with metabolic alterations in TNBC. Given the high level of heterogeneity among this BC subtype, TBC1Ds could represent important tools in predicting prognosis and guiding therapy decision-making.

EZH2 mutation is associated with the development of visceral metastasis by enhancing proliferation and invasion and inhibiting apoptosis in breast cancer cells.

BACKGROUND: The prognosis of breast cancer patients with visceral metastasis (VM) is significantly worse than that of patients without VM. We aimed to evaluate EZH2 (enhancer of zeste homolog 2) mutation as a biomarker associated with VM. METHODS: Data from forty-nine patients with metastatic breast cancer (MBC) pathologically confirmed at our hospital between March 2016 and September 2018 were collected. Metastatic tissue samples were obtained via ultrasound-guided needle biopsy, and paired peripheral blood samples were also collected. Tissue and blood samples were subjected to targeted next-generation sequencing via a 247-gene panel. Stably transfected MDA-MB-231 cells expressing wild-type EZH2 (EZH2WT) or a mutant form of EZH2 (EZH2K515R) were generated. Cell proliferation, colony formation ability, migration and invasion abilities and apoptosis were assessed using CCK-8 assays, plate colony formation assays, Transwell chamber assays and flow cytometry. RESULTS: The incidence of EZH2 mutations in the VM subgroup was greater than that in the non-VM subgroup in the entire cohort (n = 49, 42.3% vs. 13.0%, p = 0.024) and in the triple-negative breast cancer (TNBC) subgroup (n = 20, 50.0% vs. 10.0%, p = 0.05). Patients carrying EZH2 mutations had a significantly greater risk of developing VM than did those in the non-EZH2 mutation group in the entire cohort (HR 2.9) and in the TNBC subgroup (HR 6.45). Multivariate analysis revealed that EZH2 mutation was an independent prognostic factor for VM (HR 2.99, p = 0.009) in the entire cohort and in the TNBC subgroup (HR 10.1, p = 0.006). Data from cBioPortal also showed that patients with EZH2 mutations had a significantly greater risk of developing VM (HR 3.1), and the time to develop VM was significantly earlier in the EZH2 mutation group (31.5 months vs. 109.7 months, p = 0.008). Multivariate analysis revealed that EZH2 mutation (HR 2.73, p = 0.026) was an independent factor for VM after breast cancer surgery. There was no correlation between EZH2 mutations and BRCA1/2 mutations. Most of the patients (81.8%) in our cohort who developed VM carried the "c.1544A > G (p.K515R)" mutation. Compared with EZH2WT MDA-MB-231 cells, EZH2K515R MDA-MB-231 cells had greater colony formation rates (p < 0.01), greater migration and invasion rates (p < 0.001), and lower apoptosis rates (p < 0.01). The proportion of S + G2/M phase cells in the EZH2K515R group was significantly greater than that in the EZH2WT group. CONCLUSIONS: EZH2 mutation is associated with VM development in breast cancer patients. The EZH2K515R mutation leads to VM and a poor prognosis by enhancing proliferation and invasion and inhibiting apoptosis in breast cancer cells.

FDA-approved antivirals ledipasvir and daclatasvir downregulate the Src-EPHA2-Akt oncogenic pathway in colorectal and triple-negative breast cancer cells.

Direct-acting antivirals ledipasvir (LDV) and daclatasvir (DCV) are widely used as part of combination therapies to treat Hepatitis C infections. Here we show that these compounds inhibit the proliferation, invasion, and colony formation of triple-negative MDA-MB-231 breast cancer cells, SRC-transduced SW620 colon cancer cells and SRC- transduced NIH3T3 fibroblasts. DCV also inhibits the expression of PDL-1, which is responsible for resistance to immunotherapy in breast cancer cells. The demonstrated low toxicity in many Hepatitis C patients suggests LDV and DCV could be used in combination therapies for cancer patients. At the molecular level, these direct-acting antivirals inhibit the phosphorylation of Akt and the ephrin type A receptor 2 (EPHA2) by destabilizing a Src-EPHA2 complex, although they do not affect the general kinase activity of Src. Thus, LDV and DCV could be effective drugs for Src-associated cancers without the inherent toxicity of classical Src inhibitors.

Protease activated receptor-1 regulates mixed lineage kinase-3 to drive triple-negative breast cancer tumorigenesis.

Triple-negative breast cancer (TNBC) is difficult to treat breast cancer subtype due to lack or insignificant expressions of targetable estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2). Therefore, finding a targetable protein or signaling pathway in TNBC would impact patient care. Here, we report that a member of the Mixed Lineage Kinase (MLK) family, MLK3, is an effector of G-protein-coupled protease-activated receptors 1 (PAR1) and targeting MLK3 by a small-molecule inhibitor prevented PAR1-mediated TNBC tumorigenesis. In silico and immunohistochemistry analysis of human breast tumors showed overexpression of PAR1 and MLK3 in TNBC tumors. Treating α-thrombin and PAR1 agonist increased MLK3 and JNK activities and induced cell migration in TNBC cells. The PAR1 positive/high (PAR1+/hi) population of TNBC cells showed aggressive tumor phenotype with increased MLK3 signaling. Moreover, combined inhibition of the PAR1 and MLK3 mitigated the TNBC tumor burden in preclinical TNBC models. Our data suggests that activation of the PAR1-MLK3 axis promotes TNBC tumorigenesis. Therefore, combinatorial therapy targeting MLK3 and PAR1 could effectively reduce TNBC tumor burden.

NAC1 promotes stemness and regulates myeloid-derived cell status in triple-negative breast cancer.

Triple negative breast cancer (TNBC) is a particularly lethal breast cancer (BC) subtype driven by cancer stem cells (CSCs) and an immunosuppressive microenvironment. Our study reveals that nucleus accumbens associated protein 1 (NAC1), a member of the BTB/POZ gene family, plays a crucial role in TNBC by maintaining tumor stemness and influencing myeloid-derived suppressor cells (MDSCs). High NAC1 expression correlates with worse TNBC prognosis. NAC1 knockdown reduced CSC markers and tumor cell proliferation, migration, and invasion. Additionally, NAC1 affects oncogenic pathways such as the CD44-JAK1-STAT3 axis and immunosuppressive signals (TGFß, IL-6). Intriguingly, the impact of NAC1 on tumor growth varies with the host immune status, showing diminished tumorigenicity in natural killer (NK) cell-competent mice but increased tumorigenicity in NK cell-deficient ones. This highlights the important role of the host immune system in TNBC progression. In addition, high NAC1 level in MDSCs also supports TNBC stemness. Together, this study implies NAC1 as a promising therapeutic target able to simultaneously eradicate CSCs and mitigate immune evasion.

TRPS1, a sensitive marker for different histological and molecular types of breast cancer.

OBJECTIVES: We explored Trichorhinophalangeal syndrome type 1 (TRPS1) expression in special types of breast carcinoma, and analyzed the correlation between TRPS1 and androgen receptor (AR) expression in triple-negative breast cancer (TNBC). METHODS: TRPS1 expression was analyzed in 801 patients with special types of breast carcinoma. A total of 969 TNBC were used to analyze the correlation between the expression of TRPS1 and AR. TRPS1 expression was evaluated in 1975 cases of breast cancer with different molecular types. RESULTS: A total of 801 special types of breast cancers were stained with TRPS1.TRPS1 was positive in 100% (63/63) of mucinous carcinoma, 100% (7/7) adenoid cystic carcinomas (4 classic adenoid cystic carcinomas and 3 solid-basaloid adenoid cystic carcinomas), 100% (4/4) tubular carcinomas, 100% (2/2) secretory carcinomas, and 99.59% (243/244) invasive lobular carcinomas, 99.26% (267/269) invasive micropapillary carcinomas, 97.44% (38/39) ER-positive neuroendocrine tumors, 94.44% (34/36) metaplastic breast carcinomas (MBCs), 63.73% (65/102) apocrine carcinomas. TRPS1 was negative in all triple-negative neuroendocrine carcinomas (0/7).TRPS1 was positive in 92.86% (26/28) of metastatic special types of breast cancer. TRPS1 and AR expression were analyzed in 969 cases of TNBC. 90.40% were positive for TRPS1, and 42.41% were positive for AR. A significant inverse correlation between TRPS1 and AR expression was shown in TNBC (p < .001). TRPS1 showed a higher positive rate (93.13%) in TNBC compared to GATA binding protein 3 (GATA3), gross cystic disease fluid protein 15 (GCDFP-15) and forkhead box transcription Factor C 1 (FOXC1). CONCLUSIONS: In conclusion, our study demonstrated that TRPS1 is a highly sensitive marker for most special types of breast carcinoma. TRPS1 was positive in 63.73% of apocrine carcinomas. TRPS1 and AR expression was inversely correlated in TNBC.

Breast Cancer Stem Cells Upregulate IRF6 in Stromal Fibroblasts to Induce Stromagenesis.

The microenvironment of a cancer stem cell (CSC) niche is often found in coexistence with cancer-associated fibroblasts (CAFs). Here, we show the first in-depth analysis of the interaction between primary triple-negative breast cancer stem cells (BCSCs) with fibroblasts. Using 2D co-culture models with specific seeding ratios, we identified stromal fibroblast aggregation at the BCSC cluster periphery, and, on closer observation, the aggregated fibroblasts was found to encircle BCSC clusters in nematic organization. In addition, collagen type I and fibronectin accumulation were also found at the BCSC-stromal periphery. MACE-Seq analysis of BCSC-encapsulating fibroblasts displayed the transformation of stromal fibroblasts to CAFs and the upregulation of fibrosis regulating genes of which the Interferon Regulatory Factor 6 (IRF6) gene was identified. Loss of function experiments with the IRF6 gene decreased fibroblast encapsulation around BCSC clusters in 2D co-cultures. In BCSC xenografts, fibroblast IRF6 expression led to an increase in the stromal area and fibroblast density in tumors, in addition to a reduction in necrotic growth. Based on our findings, we propose that fibroblast IRF6 function is an important factor in the development of the stromal microenvironment and in sustaining the BCSC tumor niche.

Digital Whole Slide Image Analysis of Elevated Stromal Content and Extracellular Matrix Protein Expression Predicts Adverse Prognosis in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with a poor prognosis and limited treatment options. This study evaluates the prognostic value of stromal markers in TNBC, focusing on the tumor-stroma ratio (TSR) and overall stroma ratio (OSR) in whole slide images (WSI), as well as the expression of type-I collagen, type-III collagen, and fibrillin-1 on tissue microarrays (TMAs), using both visual assessment and digital image analysis (DIA). A total of 101 female TNBC patients, primarily treated with surgery between 2005 and 2016, were included. We found that high visual OSR correlates with worse overall survival (OS), advanced pN categories, lower stromal tumor-infiltrating lymphocyte count (sTIL), lower mitotic index, and patient age (p < 0.05). TSR showed significant connections to the pN category and mitotic index (p < 0.01). High expression levels of type-I collagen (>45%), type-III collagen (>30%), and fibrillin-1 (>20%) were linked to significantly worse OS (p = 0.004, p = 0.013, and p = 0.005, respectively) and progression-free survival (PFS) (p = 0.028, p = 0.025, and p = 0.002, respectively), validated at the mRNA level. Our results highlight the importance of stromal characteristics in promoting tumor progression and metastasis and that targeting extracellular matrix (ECM) components may offer novel therapeutic strategies. Furthermore, DIA can be more accurate and objective in evaluating TSR, OSR, and immunodetected stromal markers than traditional visual examination.

USP1-mediated deubiquitination of KDM1A promotes the malignant progression of triple-negative breast cancer.

Previous research has indicated the highly expressed lysine-specific histone demethylase 1A (KDM1A) in several human malignancies, including triple-negative breast cancer (TNBC). However, its detailed mechanisms in TNBC development remain poorly understood. The mRNA levels of KDM1A and Yin Yang 1 (YY1) were determined by RT-qPCR analysis. Western blot was performed to measure KDM1A and ubiquitin-specific protease 1 (USP1) protein expression. Cell proliferation, apoptosis, invasion, migration and stemness were evaluated by MTT assay, EdU assay, flow cytometry, transwell invasion assay, wound-healing assay and sphere-formation assay, respectively. ChIP and dual-luciferase reporter assays were conducted to determine the relationship between YY1 and KDM1A. Xenograft tumor experiment and IHC were carried out to investigate the roles of USP1 and KDM1A in TNBC development in vivo. The highly expressed KDM1A was demonstrated in TNBC tissues and cells, and KDM1A knockdown significantly promoted cell apoptosis, and hampered cell proliferation, invasion, migration, and stemness in TNBC cells. USP1 could increase the stability of KDM1A via deubiquitination, and USP1 depletion restrained the progression of TNBC cells through decreasing KDM1A expression. Moreover, YY1 transcriptionally activated KDM1A expression by directly binding to its promoter in TNBC cells. Additionally, USP1 inhibition reduced KDM1A expression to suppress tumor growth in TNBC mice in vivo. In conclusion, YY1 upregulation increased KDM1A expression via transcriptional activation. USP1 stabilized KDM1A through deubiquitination to promote TNBC progression.

JARID2 activation by NFYA promotes stemness of triple-negative breast cancer cells through the PI3K/AKT pathway.

BACKGROUND: This study aimed to investigate the role of Jumonji AT Rich Interacting Domain 2 (JARID2) in regulating triple-negative breast cancer (TNBC) stemness and its mechanism. RESEARCH DESIGN AND METHODS: Bioinformatics analysis examined JARID2 expression, prognosis, and transcription factors. Quantitative polymerase chain reaction, western blot, and immunohistochemistry detected expression. Dual luciferase reporter gene and chromatin immunoprecipitation assays verified binding. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assay detected viability and proliferation. Sphere formation assay detected the sphere formation efficiency. Flow cytometry detected CD44+/CD24- -marked stem cells. A xenograft tumor model verified the effect of JARID2 in vivo. RESULTS: JARID2 and nuclear transcription factor Y subunit α (NFYA) were upregulated in TNBC tissues and positively correlated. Knockdown of JARID2 or NFYA inhibited cell stemness by inhibiting the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/AKT) signaling pathway. Enforced JARID2 expression rescued the suppressive effect of NFYA knockdown on the PI3K/AKT signaling pathway and cell stemness. Knockdown of JARID2 inhibited tumor growth and cell stemness in mice but was alleviated by concurrent overexpression of NFYA. CONCLUSIONS: NFYA promotes TNBC cell stemness by upregulating JARID2 expression and regulating the PI3K/AKT signaling pathway, suggesting JARID2 as a potential target for innovating drugs that target TNBC stem cells.

Prediction of early clinical response to neoadjuvant chemotherapy in Triple-negative breast cancer: Incorporating Radiomics through breast MRI.

This study assessed pretreatment breast MRI coupled with machine learning for predicting early clinical responses to neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC), focusing on identifying non-responders. A retrospective analysis of 135 TNBC patients (107 responders, 28 non-responders) treated with NAC from January 2015 to October 2022 was conducted. Non-responders were defined according to RECIST guidelines. Data included clinicopathologic factors and clinical MRI findings, with radiomics features from contrast-enhanced T1-weighted images, to train a stacking ensemble of 13 machine learning models. For subgroup analysis, propensity score matching was conducted to adjust for clinical disparities in NAC response. The efficacy of the models was evaluated using the area under the receiver-operating-characteristic curve (AUROC) before and after matching. The model combining clinicopathologic factors and clinical MRI findings achieved an AUROC of 0.752 (95% CI 0.644-0.860) for predicting non-responders, while radiomics-based models showed 0.749 (95% CI 0.614-0.884). An integrated model of radiomics, clinicopathologic factors, and clinical MRI findings reached an AUROC of 0.802 (95% CI 0.699-0.905). After propensity score matching, the hierarchical order of key radiomics features remained consistent. Our study demonstrated the potential of using machine learning models based on pretreatment MRI to non-invasively predict TNBC non-responders to NAC.

Combined knockdown of CD151 and MMP9 may inhibit the malignant biological behaviours of triple-negative breast cancer through the GSK-3ß/ß-catenin-related pathway.

Triple-negative breast cancer (TNBC) represents a significant health concern for women worldwide, and the overproduction of MMP9 and CD151 is associated with various cancers, influencing tumour growth and progression. This study aimed to investigate how CD151 and MMP9 affect TNBC cell migration, apoptosis, proliferation, and invasion. Immunohistochemical experiments revealed that CD151 and MMP9 were positively expressed in triple-negative breast cancer, and lymph node metastasis, the histological grade, and CD151 and MMP9 expression were found to be independent prognostic factors for the survival of patients with triple-negative breast cancer. Cytological experiments indicated that the knockdown of CD151 or MMP9 slowed triple-negative breast cancer cell growth, migration, and invasion and increased the apoptosis rate. Compared with CD151 knockdown, double MMP9 and CD151 knockdown further promoted cell death and inhibited TNBC cell proliferation, migration, and invasion. Moreover, ß-catenin and p-GSK-3ß were significantly downregulated. In summary, simultaneously silencing CD151 and MMP9 further suppressed the proliferation, migration and invasion of TNBC cells and promoted their apoptosis. One possible strategy for inducing this effect is to block the GSK-3ß/ß-catenin pathway.

Natural Product-Inspired Discovery of Naphthoquinone-Furo-Piperidine Derivatives as Novel STAT3 Inhibitors for the Treatment of Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, and STAT3 has emerged as an effective drug target for TNBC treatment. Herein, we employed a scaffold-hopping strategy of natural products to develop a series of naphthoquinone-furopiperidine derivatives as novel STAT3 inhibitors. The in vitro assay showed that compound 10g possessed higher antiproliferative activity than Cryptotanshinone and Napabucasin against TNBC cell lines, along with lower toxicity and potent antitumor activity in a TNBC xenograft model. Mechanistically, 10g could inhibit the phosphorylation of STAT3 and the binding affinity was determined by the SPR assay (KD = 8.30 µM). Molecule docking studies suggested a plausible binding mode between 10g and the SH2 domain, in which the piperidine fragment and the terminal hydroxy group of 10g played an important role in demonstrating the success of this evolution strategy. These findings provide a natural product-inspired novel STAT3 inhibitor for TNBC treatment.

[Effects of normal mitochondrial transplantation on proliferation, apoptosis and stemness of triple-negative breast cancer cells].

Objectives: To observe the mitochondrial morphology of normal and triple-negative breast cancer cells, extract mitochondria from normal cells, and investigate the effects of mitochondrial transplantation on proliferation, apoptosis, and stemness of triple-negative breast cancer cells. Methods: The morphology of mitochondria was observed by transmission electron microscope. Mitochondria were extracted by mitochondrial extraction kit, mitochondrial protein was identified by western blot, and mitochondrial activity was detected by mitochondrial membrane potential detection kit. MitoTracker Green or MitoTracker Deep Red fluorescent probes were used to label the mitochondria of living cells, and the degree of mitochondria entering LTT cells was observed by confocal laser microscopy at 12, 24, and 96 hours. The effects of mitochondrial transplantation on proliferation, apoptosis, and stemness of breast cancer cells were examined by CCK8, colony formation assay, flow cytometry, and sphere formation assay after 24 hours of mitochondrial transplantation. Results: The mitochondria of normal cells were rod-shaped or elongated, while the mitochondria of triple-negative breast cancer cells were swollen and vacuolated. Western blot results showed that cytochrome c oxidase subunit I (MT-CO1) protein encoded by mitochondria was present in the isolated mitochondria. The content of heat shock protein 60 (HSP60) was higher in mitochondria than that in cytoplasm. The result of the multi-mode microplate reader showed that the content of mitochondrial J-aggregates/monomer was 1.67±0.06, which was significantly higher than 0.35±0.04 of the control group (P＜0.001). Exogenous mitochondria were observed in LTT cells at 12, 24, and 96 hours after mitochondrial transplantation. The results of the CCK8 experiment showed that OD450 of LTT cells was 0.27±0.13 after 48 hours transplantation, which was lower than 0.62±0.36 of the control group (P=0.023). The OD450 of MDA-MB-468 cells was 0.30±0.03, which was lower than 0.65±0.10 of the control group (P=0.004). After 120 hours of mitochondrial transplantation, OD450 in both groups was still significantly lower than that in the control group (P＜0.01). The number of clones formed by mitochondrial transplantation of LTT cells was 21.33±7.31, which was lower than 35.22±13.59 of the control group (P=0.016). Flow cytometry showed that the early apoptosis rate of LTT cells was (30.07±2.15)% after 24 hours of mitochondrial transplantation, which was higher than 2.07±1.58 of the control group (P＜0.001). The proportion of early apoptosis in MDA-MB-468 cells was 24.47%±5.22%, which was higher than (7.83±2.06)% in the control group (P=0.007). In addition, the number of mitochondria transplanted LTT cells into the cell sphere was 46.25±5.40, which was significantly lower than 62.58±6.43 of the control group (P＜0.001). Conclusion: Normal mitochondria can enter triple-negative breast cancer cells by co-culture, inhibit the proliferation and stemness of triple-negative breast cancer cells, and promote the apoptosis of triple-negative breast cancer cells.

[Retrospective analysis of metaplastic breast cancer cases]. / A metaplasztikus emlodaganat retrospektív elemzése.

Metaplastic breast tumour is a rare, aggressive, mostly triple- negative, dedifferentiated malignancy, which poorly responds to chemotherapy compared to other invasive breast tumours. Since 2000, the WHO has considered it as a separate entity among breast tumours. Given the extremely poor prognosis of the tumour, more studies are needed to establish the most effective treatment strategy supported by data to increase overall survival. The objective of our research was a retrospective analysis of 77 patients with metaplastic breast cancer treated between 01.01.2012 and 28.02.2023 at our institute. Following the descriptive statistics of the patients, the pathological or clinical response was examined in cases of 15 patients treated with neoadjuvant and 14 patients with palliative chemotherapy. Finally, we compared the overall and progression-free survival of metaplastic breast cancer patients treated at our institute with those described in the international literature. The research results, both at our institute and in the literature, are limited by the small number of cases. In our research, with similar numbers of cases as many other investigations, we obtained results close to international data, thereby supporting the collection of data and further research necessary for the most effective treatment strategy for this rare tumour.

Puerarin Decreases the Expression of FUS-Dependent MAPK4 to Inhibit the Development of Triple-Negative Breast Cancer.

Puerarin has been reported to have anticancer properties; however, its mechanism in regulating triple-negative breast cancer (TNBC) remains unclear. Cell function was assessed using a cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine assay, flow cytometry, and transwell assay. Additionally, the glucose assay kit, lactate assay kit, and ADP/ATP ratio assay kit were used to analyze glucose metabolism. mRNA and protein expression levels were analyzed using qRT-PCR and western blotting assays, respectively. The relationship between FUS RNA binding protein (FUS) and mitogen-activated protein kinase 4 (MAPK4) was determined using an RNA immunoprecipitation assay. TNBC cell malignancy in vitro was validated using a xenograft mouse model assay. Puerarin treatment or MAPK4 knockdown effectively inhibited TNBC cell proliferation, invasion, and glucose metabolism, and induced cell apoptosis. Additionally, puerarin treatment downregulated MAPK4 and FUS expression. Conversely, MAPK4 overexpression attenuated the effects of puerarin in TNBC cells. FUS stabilized MAPK4 mRNA expression in TNBC cells. Furthermore, puerarin decreased MAPK4 expression by downregulating FUS in TNBC cells. Finally, puerarin inhibited tumor formation in vivo. Puerarin inhibited TNBC development by decreasing the expression of FUS-dependent MAPK4, indicating that puerarin may serve as a promising therapeutic agent to hind TNBC.

[Biological characteristics of triple negative breast cancer with low expression of HER2].

Objective: To investigate the biological characteristics of triple negative breast cancer (TNBC) with low expression of HER2 (HER2-low). Methods: A total of 93 TNBC cases in Shanxi Cancer Hospital from 2017 to 2019 were collected and divided into HER2-negative and HER2-low groups according to HER2 expression status. The clinicopathological features and prognostic differences between the two groups were retrospectively analyzed and compared, and genetic detection of tumor tissues was performed to clarify somatic mutation status and differences between the two groups. Results: Ninety-three patients aged 26 to 86 years were enrolled, including 60 patients in the HER2-negative group and 33 patients in the HER2-low group. The distribution of HER2-low in luminal androgen receptor (LAR) subtype (14/23, 60.87%) and non-LAR subtype (19/70, 27.14%) was significantly different (P=0.005). There were no significant differences in age, pT stage, histological grade, infiltration mode, lymph node metastasis and survival analysis. The expression of HER2-low in the tumor was heterogeneous, including different proportions of weak, weak to moderate intensity, and incomplete to intact membrane staining. With the change of the proportion of HER2-positive cells, the different distribution of those cells in the total tumor cells was noted, including cluster, mosaic and scattered patterns. The concentration and quality of DNA extracted from 71 of the 93 samples met the requirements for making libraries, including 43 in the HER2-negative group and 28 in the HER2-low group. Genetic mutations were mainly missense mutations, single nucleotide mutations, and point mutations in which base C was replaced by base T. There was no significant difference in genes with mutation frequency>3 times between the two groups. CTNNB1 and FGFR3 genes were only mutated in HER2-low group; while ALK, CYP2D6 and FAT1 genes were only mutated in HER2-negative group. HER2-low group included 18 HER2 1+ cases and 10 HER2 2+ cases. Genes with mutation frequency>3 times between the two groups included PIK3CA, TP53, SLX4, ATM and BRCA1. The mutation frequency of PIK3CA in HER2 2+ was significantly higher than that in HER2 1+ group (P<0.05), and SLX4 gene was only mutated in HER2 1+ group. Conclusions: There are some differences of histological morphology and genetic variation between HER2-negative group and HER2-low group, and also differences in genetic variation between HER2 1+ and HER2 2+ in HER2-low group, which are helpful for more accurate stratification of TNBC and useful for finding the therapeutic target and precise treatment of HER2-low TNBC.