Breast Cancer Research最新文献

Background: Circulating tumor cell (CTC) clusters exhibit significantly greater metastatic potential than single CTCs and are associated with poorer overall survival in cancers. However, the molecular mechanisms driving CTC cluster formation remain unclear. p21-activated kinase 2 (PAK2) plays a critical role in cytoskeletal remodeling and is frequently associated with advanced tumor progression and poor prognosis. In this study, we explored the role of PAK2 in CTC cluster formation in breast cancer.

Methods: We performed an integrated bioinformatics analysis of transcriptomic profiles from single CTCs and CTC clusters via GEO datasets to identify differentially expressed genes (DEGs) and candidate hub genes associated with CTC clustering. Functional enrichment analyses and gene set enrichment analysis were subsequently conducted to explore relevant pathways. The biological function of the identified hub gene PAK2 was validated via in vitro CTC cluster formation cell models and in vivo orthotopic in situ breast cancer mouse models. Mechanistic studies focused on PAK2-mediated phosphorylation of E-cadherin. Additionally, the therapeutic potential of targeting PAK2 was evaluated via the use of the selective PAK inhibitor FRAX597 in vivo.

Results: Bioinformatics analyses revealed that CTC clusters are characterized by enhanced cell-cell adhesion, increased proliferative capacity and survival advantages. Among the identified hub genes, PAK2 was significantly upregulated in breast cancer tissues and cell lines, and its elevated expression was associated with poor patient prognosis. Functional experiments demonstrated that PAK2 promotes CTC cluster formation by increasing E-cadherin phosphorylation at Ser840, thereby strengthening cell-cell adhesion. Pharmacologic inhibition of PAK2 with FRAX597 impaired CTC cluster formation, suppressed tumor growth, reduced metastasis and decreased CTC cluster numbers in vivo.

Conclusions: This study revealed that PAK2 promotes CTC cluster formation and breast cancer metastasis by enhancing E-cadherin-mediated cell-cell adhesion. These results provide novel insights into the molecular mechanisms underlying CTC cluster formation and highlight PAK2 as a potential therapeutic target and diagnostic marker for preventing breast cancer metastasis.

Background: Triple negative breast cancer (TNBC), characterized by its aggressive clinical behavior and propensity for distant metastasis, presents critical challenges in therapeutic management. Emerging evidence implicates lipid metabolic reprogramming as a key facilitator of tumor progression and metastatic dissemination. However, the precise molecular mechanisms underlying lipid metabolic dysregulation in TNBC metastasis remain poorly characterized. Our work systematically elucidates the mechanistic role of ALDH3A2 in orchestrating lipid metabolic adaptations that drive breast cancer metastasis.

Methods: Transcriptomic analysis of clinical datasets identified metastasis-related metabolic regulators. Cellular migration/invasion assays and murine metastasis models were utilized to assess metastatic effects of ALDH3A2. Lipidomic profiling coupled with pathway analysis characterized metabolic alterations. Mechanistic studies integrated western blot analysis with lipid droplet quantification. Computational approaches including structure-based virtual screening and molecular docking simulations were employed for inhibitor discovery.

Results: ALDH3A2 was significantly upregulated in TNBC clinical specimens and showed significant association with adverse clinical outcomes. Functional validation confirmed that ALDH3A2 potentiates TNBC cell migration/invasion through epithelial-mesenchymal transition (EMT) activation. Metabolic profiling revealed ALDH3A2-driven lipid accumulation, evidenced by increased lipid droplet formation and elevated triglyceride levels. Specifically, arachidonic acid (AA) enrichment was observed in ALDH3A2-overexpressing cells, corresponding to enhanced glycerophospholipid metabolism. Mechanistic studies demonstrated that ALDH3A2-mediated AMP/ATP imbalance suppresses AMPK phosphorylation while activating mTOR/SREBP1 signaling. mTOR inhibition effectively attenuated ALDH3A2-induced lipid metabolic alterations. Importantly, oxaliplatin was identified as a potential therapeutic agent targeting ALDH3A2-mediated AA metabolism to suppress metastasis.

Conclusions: Our work establishes ALDH3A2 as a pivotal regulator of lipid metabolic reprogramming in TNBC metastasis, providing mechanistic insights into AA-mediated tumor progression. These findings position ALDH3A2 as a promising therapeutic target and prognostic biomarker for TNBC management.

Background: Cancer progression is driven by somatic mutations, with alterations in driver genes such as tumor suppressors and oncogenes playing critical roles. In breast cancer (BRCA), mutations in MAP3K1 and MAP2K4 are recurrent, especially in estrogen receptor-positive (ER⁺) subtypes, yet their functional significance and mechanistic contributions remain incompletely understood. This study aims to elucidate the role of MAP3K1/MAP2K4 mutations in BRCA pathogenesis.

Methods: We performed integrated genomic analyses using data from The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohorts. Functional validation was conducted in breast cancer cell lines (e.g., MCF-7, ZR-75-1) using shRNA-mediated knockdown, overexpression of dominant-negative MKK4 (MKK4DN), and western blotting. In vivo tumor growth and metastasis were assessed using a xenograft mouse model. Proteomic and phosphoproteomic data from Clinical Proteomic Tumor Analysis Consortium (CPTAC) were analyzed to evaluate JNK pathway activity and FOSL1 expression across multiple cancer types.

Results: MAP3K1 and MAP2K4 were identified as frequently mutated in BRCA, with mutation spectra dominated by loss-of-function alterations. These mutations exhibited mutual exclusivity with TP53 alterations and were enriched in ER + tumors. Mechanistically, MAP3K1/MAP2K4 loss led to reduced JNK2 phosphorylation, impaired p53 activation at Ser15, and subsequent upregulation of FOSL1 (encoding FRA1), promoting tumor proliferation and metastasis. In vivo, MKK4DN (dominant-negative MAP2K4) expression enhanced tumor growth and lung metastasis, accompanied by decreased phospho-JNK/p53 and increased FRA1. Pan-cancer analysis revealed that MAP3K1/MAP2K4 mutations compensate for TP53 loss in regulating FOSL1 expression, particularly in tumors with moderate TP53 mutation rates.

Conclusions: Our findings establish MAP3K1 and MAP2K4 as key tumor suppressors in BRCA that operate via the JNK2-p53-FOSL1 axis. Their inactivation provides an alternative mechanism for p53 pathway disruption, adhering to the "minimal necessary alteration" principle in cancer signaling. This study highlights the dual regulatory mechanisms controlling FRA1 expression and offers insights into breast cancer heterogeneity, with potential implications for targeted therapy and patient stratification.

Background: Molecular breast imaging (MBI) has shown utility as a supplement to mammography in women with dense breasts. Background parenchymal uptake (BPU), which describes the level of Tc-99 m sestamibi in fibroglandular tissue on MBI, varies among women with similar density. Higher BPU is associated with greater breast cancer risk. The goal of this work is to investigate the histological correlations of BPU that may explain this association with risk.

Methods: In healthy women with dense tissue on mammography, we prospectively biopsied regions of fibroglandular tissue exhibiting one of the extreme categories of BPU on MBI: either photopenic or marked. Tissue composition of specimens was assessed by measuring area of epithelium, stroma, and fat and counting lobules. Lobular involution status was assessed by an expert pathologist as either none, partial, or complete. Ki-67 index and estrogen receptor-alpha expression were also assessed. Histologic features of photopenic and marked specimens were compared.

Results: Biopsies were performed in 48 women (mean age 54.9 years [SD 11.1 years]), including 20 with marked BPU and 28 with photopenic BPU. Women with marked BPU were younger (mean age 49.9 vs. 58.4 years, p = 0.004), had higher body mass index (p = 0.01), and were more likely premenopausal (p = 0.005). Marked BPU specimens had a higher proportion of epithelium (14.5% vs. 2.2%, p < 0.001), lower stromal content (44.8% vs. 84.2%, p = 0.005), similar fat (18.9% vs. 12.9%, p = 0.41), and greater lobule counts (15.5 vs. 6.3, p < 0.001) compared to photopenic specimens. Complete lobular involution was less frequent in marked tissue than in photopenic tissue (10.5% vs. 76%, p < 0.001). Ki-67 index was higher in marked BPU tissues (5.4% vs. 1.6%, p = 0.006), though the difference was attenuated after adjustment for epithelial area (p = 0.26). Estrogen receptor-alpha expression did not differ between marked and photopenic groups (25.6% vs. 28.4%, p = 0.12).

Conclusions: Marked BPU on MBI is associated with greater epithelial content, less lobular involution, and higher proliferative activity-features characteristic of tissue at elevated risk for malignant transformation. These findings suggest that BPU provides functional information beyond mammographic density, supporting its role as an imaging biomarker for breast cancer risk in women with dense breasts.

Trial registration: NCT01240278 || 11/15/2010 and NCT01588834 || 05/01/2012.

Background: Protagonistic role of platelets promote capillary infiltration of tumors for distant metastasis along with immunosurveillance. Despite existing reports highlighting role of platelets in tumorigenesis, its impact on breast cancer stem cells (BCSCs) remain underexplored. Our first ever report on murine and human system, accentuate that, tumor educated platelets (TEPs) of luminal A and TNBC subtypes are distinct from healthy counterparts, collaborating with BCSCs to generate sub-variants that elevate tumor aggressiveness.

Methods: Impact of TEPs on BCSCs was evaluated from primary breast tumor and blood samples of luminal A/TNBC patients along with EC/4T1 murine breast tumor models and MCF-7/MDA-MB-231 cell lines. For downstream assays, TEPs were co-cultured with breast tumor samples or cell lines, followed by magnetic sorting of lin^-CD44⁺CD24^- BCSCs. TEP induced alterations of BCSCs were evaluated from 3D tumorsphere, colony formation, transwell migration, scratch-wound healing, matrigel invasion, in-vitro tube formation assays. Fluorescence-confocal microscopy, RT-PCR, flow-cytometry, western-blotting was utilized to decipher the role of genes and protein involved in stemness, metastasis along with the transcription factors in the downstream signaling cascade, followed by verifications by RNAi.

Results: TEPs have elevated expression of P-selectin and interacts with BCSCs via P-selectin and PSGL1 on BCSCs surface. Treatment with aspirin had restorative impact on P-selectin level, converting TEPs from active to resting platelet (RP) state. Under TEPs influence, BCSCs were tumorigenic, clonogenic, multidrug resistant, invasive with numerous invadopodia and remained skewed towards mesenchymal phenotype. Administration of RP reduced TEP associated BCSC virulence both in-vivo and in-vitro. P-selectin-PSGL1 interaction results in binding of WNT to FRIZZLED followed by stabilization and nuclear translocation of β-catenin. Nuclear β-catenin promotes stemness-EMT (Epithelial to mesenchymal transition)-metastasis, along with stimulation of autocrine VEGF-VEGFR2 cascade. Inhibition of WNT and VEGFR2 by RNAi confirmed the critical role of this axis in regulating TEP's influence on BCSCs.

Conclusion: These insights into TEP-BCSC interplay, acknowledges TEPs, as-well-as unveils novel receptor-ligand signaling cascade between TEPs and BCSCs, that could be a beneficial therapeutic strategy to target cancer metastasis.

Background: ​​Triple-negative breast cancer (TNBC) patients exhibiting high PD-L1 expression demonstrate poor responses to anti-PD-L1 therapy and aggressive lung metastasis. The paradoxical role of PD-L1 beyond its immune checkpoint function and the impact of interferon-γ-secreted during immunotherapy-on metastasis remain poorly understood.

Methods: Integrated reanalysis of single-cell RNA sequencing (scRNA-seq) data from TNBC lung metastases identified enriched signaling pathways. IFN-γ function was assessed using murine and human TNBC cell lines, employing in vitro assays and in vivo modeling in both immunocompetent and immunodeficient mice. CRISPR/Cas9-mediated PD-L1 ablation, pharmacological inhibitors, RNA sequencing (RNA-seq), chromatin immunoprecipitation sequencing (ChIP-seq), co-immunoprecipitation (Co-IP), bioinformatics analyses, and in vivo metastasis assays were utilized to dissect underlying mechanisms.

Results: scRNA-seq revealed significant enrichment of IFN-γ signaling within a distinct metastatic TNBC cluster. IFN-γ pretreatment potently enhanced the lung metastatic capacity of TNBC cells in both immunocompetent and immunodeficient murine models. CRISPR/Cas9-mediated PD-L1 ablation abolished IFN-γ-driven metastasis without affecting proliferation, indicating an immune checkpoint-independent mechanism. Mechanistically, IFN-γ facilitated HDAC2-mediated deacetylation of PD-L1, promoting its nuclear translocation. RNA-seq identified lymphocyte antigen 6 complex locus E (LY6E) as a key downstream effector, with expression correlating with PD-L1 in TNBC patient samples. Nuclear PD-L1 bound to the RNA polymerase II subunit POLR2A to form a transcriptional complex that directly activated LY6E expression, thereby driving metastatic dissemination.

Conclusion: Our findings unveil a novel IFN-γ-nuclear PD-L1/POLR2A-LY6E signaling axis critical for TNBC lung metastasis. This immune-independent mechanism, driven by nuclear PD-L1 transcriptional activity, provides a mechanistic basis for the limited efficacy of anti-PD-L1 antibodies against metastasis and nominates nuclear PD-L1 complexes and LY6E as potential therapeutic targets to overcome metastatic resistance in TNBC.

Background: Breast cancer (BC) remains the most commonly diagnosed malignancy among women worldwide, with metabolic dysregulation of glucose and hyperinsulinemia increasingly recognised as contributors to its development and progression. However, despite accumulating evidence linking metabolic imbalances to tumorigenesis, the precise therapeutic opportunities arising from targeting these metabolic pathways remain insufficiently defined.

Objective: To explore the potential of metformin and its derivatives, in combination with other anticancer agents, to suppress BC cell proliferation by targeting glucose metabolism.

Results: Preclinical and epidemiological evidence indicates that metformin may reduce BC incidence and improve survival, with particularly pronounced benefits observed in triple-negative and Human Epidermal Growth Factor Receptor 2(HER2) positive subtypes, especially when used in combination with chemotherapy or targeted therapies. The drug's anticancer potential is mediated through both systemic and tumor-intrinsic mechanisms. Systemically, metformin enhances insulin sensitivity and suppresses hepatic glucose production, thereby lowering circulating insulin and IGF-1 levels and attenuating growth factor-driven proliferation. At the tumor level, it activates AMP-activated protein kinase, inhibits the mammalian target of rapamycin pathway, disrupts mitochondrial oxidative phosphorylation, and induces apoptosis through metabolic stress. In addition, novel biguanide derivatives have demonstrated superior antitumor efficacy by inducing cell-cycle arrest at the G0/G1 and G2/M phases and inhibiting cancer cell migration, underscoring the therapeutic promise of structural modifications. However, despite these encouraging findings, restuls from large clinical trials have been inconsistent, particularly in non-diabetic populations, and the extent to which metformin's metabolic effects translate into direct oncologic benefit remains unclear. Importantly, elevated systemic insulin and IGF-1 remain key drivers of mitogenic and anti-apoptotic signaling in breast epithelial cells, reinforcing the rationale for targeting metabolic vulnerabilities in BC prevention and therapy.

Conclusion: Metformin and its derivatives exert dual anticancer effects by modulating systemic insulin signaling and targeting tumor-intrinsic pathways. Nevertheless, inconsistencies between preclinical efficacy and clinical outcomes highlight the need for biomarker-guided approaches and deeper investigation into tumour-specific metabolic contects. These complementary mechanisms highlight their potential in precision BC therapy, warranting biomarker-driven studies and optimized therapeutic combinations.