E3 ubiquitin ligase BCA2 promotes breast cancer stemness by up-regulation of SOX9 by LPS.

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer. Breast cancer stem cells (BCSCs) are believed to play a crucial role in the carcinogenesis, therapy resistance, and metastasis of TNBC. It is well known that inflammation promotes stemness. Several studies have identified breast cancer-associated gene 2 (BCA2) as a potential risk factor for breast cancer incidence and prognosis. However, whether and how BCA2 promotes BCSCs has not been elucidated. Here, we demonstrated that BCA2 specifically promotes lipopolysaccharide (LPS)-induced BCSCs through LPS induced SOX9 expression. BCA2 enhances the interaction between myeloid differentiation primary response protein 88 (MyD88) and Toll-like receptor 4 (TLR4) and inhibits the interaction of MyD88 with deubiquitinase OTUD4 in the LPS-mediated NF-κB signaling pathway. And SOX9, an NF-κB target gene, mediates BCA2's pro-stemness function in TNBC. Our findings provide new insights into the molecular mechanisms by which BCA2 promotes breast cancer and potential therapeutic targets for the treatment of breast cancer.

In silico identification of a novel Cdc2-like kinase 2 (CLK2) inhibitor in triple negative breast cancer.

Dysregulation of RNA splicing processes is intricately linked to tumorigenesis in various cancers, especially breast cancer. Cdc2-like kinase 2 (CLK2), an oncogenic RNA-splicing kinase pivotal in breast cancer, plays a significant role, particularly in the context of triple-negative breast cancer (TNBC), a subtype marked by substantial medical challenges due to its low survival rates. In this study, we employed a structure-based virtual screening (SBVS) method to identify potential CLK2 inhibitors with novel chemical structures for treating TNBC. Compound 670551 emerged as a novel CLK2 inhibitor with a 50% inhibitory concentration (IC50) value of 619.7 nM. Importantly, Compound 670551 exhibited high selectivity for CLK2 over other protein kinases. Functionally, this compound significantly reduced the survival and proliferation of TNBC cells. Results from a cell-based assay demonstrated that this inhibitor led to a decrease in RNA splicing proteins, such as SRSF4 and SRSF6, resulting in cell apoptosis. In summary, we identified a novel CLK2 inhibitor as a promising potential treatment for TNBC therapy.

CD163+ macrophages in the triple-negative breast tumor microenvironment are associated with improved survival in the Women's Circle of Health Study and the Women's Circle of Health Follow-Up Study.

BACKGROUND: Tumor-associated macrophages (TAMs) are a prominent immune subpopulation in the tumor microenvironment that could potentially serve as therapeutic targets for breast cancer. Thus, it is important to characterize this cell population across different tumor subtypes including patterns of association with demographic and prognostic factors, and breast cancer outcomes. METHODS: We investigated CD163+ macrophages in relation to clinicopathologic variables and breast cancer outcomes in the Women's Circle of Health Study and Women's Circle of Health Follow-up Study populations of predominantly Black women with breast cancer. We evaluated 611 invasive breast tumor samples (507 from Black women, 104 from White women) with immunohistochemical staining of tissue microarray slides followed by digital image analysis. Multivariable Cox proportional hazards models were used to estimate hazard ratios for overall survival (OS) and breast cancer-specific survival (BCSS) for 546 cases with available survival data (median follow-up time 9.68 years (IQR: 7.43-12.33). RESULTS: Women with triple-negative breast cancer showed significantly improved OS in relation to increased levels of tumor-infiltrating CD163+ macrophages in age-adjusted (Q3 vs. Q1: HR = 0.36; 95% CI 0.16-0.83) and fully adjusted models (Q3 vs. Q1: HR = 0.30; 95% CI 0.12-0.73). A similar, but non-statistically significant, association was observed for BCSS. Macrophage infiltration in luminal and HER2+ tumors was not associated with OS or BCSS. In a multivariate regression model that adjusted for age, subtype, grade, and tumor size, there was no significant difference in CD163+ macrophage density between Black and White women (RR = 0.88; 95% CI 0.71-1.10). CONCLUSIONS: In contrast to previous studies, we observed that higher densities of CD163+ macrophages are independently associated with improved OS and BCSS in women with invasive triple-negative breast cancer. Trial registration Not applicable.

Type II Interleukin-4 Receptor Activation in Basal Breast Cancer Cells Promotes Tumor Progression via Metabolic and Epigenetic Modulation.

Interleukin-4 (IL4) is a Th2 cytokine that can signal through two different receptors, one of which-the type II receptor-is overexpressed by various cancer cells. Previously, we have shown that type II IL4 receptor signaling increases proliferation and metastasis in mouse models of breast cancer, as well as increasing glucose and glutamine metabolism. Here, we expand on those findings to determine mechanistically how IL4 signaling links glucose metabolism and histone acetylation to drive proliferation in the context of triple-negative breast cancer (TNBC). We used a combination of cellular, biochemical, and genomics approaches to interrogate TNBC cell lines, which represent a cancer type where high expression of the type II IL4 receptor is linked to reduced survival. Our results indicate that type II IL4 receptor activation leads to increased glucose uptake, Akt and ACLY activation, and histone acetylation in TNBC cell lines. Inhibition of glucose uptake through the deletion of Glut1 ablates IL4-induced proliferation. Additionally, pharmacological inhibition of histone acetyltransferase P300 attenuates IL4-mediated gene expression and proliferation in vitro. Our work elucidates a role for type II IL4 receptor signaling in promoting TNBC progression, and highlights type II IL4 signaling, as well as histone acetylation, as possible targets for therapy.

Methyl CpG binding protein MBD2 has a regulatory role on the BRCA1 gene expression and its modulation by resveratrol in ER+, PR+ & triple-negative breast cancer cells.

BACKGROUND: Resveratrol has demonstrated its ability to regulate BRCA1 gene expression in breast cancer cells, and previous studies have established the binding of MBD proteins to BRCA1 gene promoter regions. However, the molecular mechanism underlying these interactions remains to be elucidated. The aimed to evaluate the impact of MBD proteins on the regulation of BRCA1, BRCA2, and p16 genes and their consequential effects on breast cancer cells. METHODS: Efficacy of resveratrol was assessed using the MTT assay. Binding interactions were investigated through EMSA, ChIP, & MeIP assay. Expression analyses of MBD genes and proteins were conducted using qRT-PCR and western blotting, respectively. Functional assays, including clonogenic, migratory, and sphere formation assays were used to assess cancer cells' colony-forming, metastatic, and tumor-forming abilities. The cytotoxicity of resveratrol on cancer cells was also tested using an apoptosis assay. RESULTS: The study determined an IC50 of 30µM for resveratrol. MBD proteins were found to bind to the BRCA1 gene promoter. Resveratrol exhibited regulatory effects on MBD gene expression, subsequently impacting BRCA1 gene expression and protein levels. Higher concentrations of resveratrol resulted in reduced colony and sphere formation, decreases migration of cancer cells, and an increases number of apoptotic cells in breast cancer cells. Impact Identification of MBD2-BRCA1 axis indicates their significant role in the induction of apoptosis and reduction of metastasis and proliferation in breast cancer cells. Further therapy can be designed to target these MBD proteins and resveratrol could be used along with other anticancer drugs to target breast cancer. CONCLUSIONS: In conclusion MBD2 protein interact to the BRCA1 gene promoter, and resveratrol modulates MBD2 gene expression, which in turn regulates BRCA1 gene expression, and inhibits cell proliferation, migration, and induces apoptosis in ER+, PR+ & Triple negative breast cancer cells.

Posttranslational protein modifications as gatekeepers of cancer immunogenicity.

Triple-negative breast cancer (TNBC) presents a formidable challenge in oncology due to its aggressive phenotype and the immunosuppressive nature of its tumor microenvironment (TME). In this issue of the JCI, Zhu, Banerjee, and colleagues investigated the potential of targeting the OTU domain-containing protein 4 (OTUD4)/CD73 axis to mitigate immunosuppression in TNBC. They identified elevated CD73 expression as a hallmark of immunosuppression in TNBC. Notably, the CD73 expression was regulated by OTUD4-mediated posttranslational modifications. Using ST80, a pharmacologic inhibitor of OTUD4, the authors demonstrated the restoration of cytotoxic T cell function and enhanced efficacy of anti-PD-L1 therapy in preclinical models. These findings underscore the therapeutic potential of targeting the OTUD4/CD73 axis in TNBC.

Overexpressing S100A9 ameliorates NK cell dysfunction in estrogen receptor-positive breast cancer.

BACKGROUND: Estrogen receptor (ER) positive human epidermal growth factor receptor 2 (HER2) negative breast cancer (ER+/HER2-BC) and triple-negative breast cancer (TNBC) are two distinct breast cancer molecular subtypes, especially in tumor immune microenvironment (TIME). The TIME of TNBC is considered to be more inflammatory than that of ER+/HER2-BC. Natural killer (NK) cells are innate lymphocytes that play an important role of tumor eradication in TME. However, studies focusing on the different cell states of NK cells in breast cancer subtypes are still inadequate. METHODS: In this study, single-cell mRNA sequencing (scRNA-seq) and bulk mRNA sequencing data from ER+/HER2-BC and TNBC were analyzed. Key regulator of NK cell suppression in ER+/HER2-BC, S100A9, was quantified by qPCR and ELISA in MCF-7, T47D, MDA-MB-468 and MDA-MB-231 cell lines. The prognosis predictability of S100A9 and NK activation markers was evaluated by Kaplan-Meier analyses using TCGA-BRAC data. The phenotype changes of NK cells in ER+/HER2-BC after overexpressing S100A9 in cancer cells were evaluated by the production levels of IFN-gamma, perforin and granzyme B and cytotoxicity assay. RESULTS: By analyzing scRNA-seq data, we found that multiple genes involved in cellular stress response were upregulated in ER+/HER2-BC compared with TNBC. Moreover, TLR regulation pathway was significantly enriched using differentially expressed genes (DEGs) from comparing the transcriptome data of ER+/HER2-BC and TNBC cancer cells, and NK cell infiltration high/low groups. Among the DEGs, S100A9 was identified as a key regulator. Patients with higher expression levels of S100A9 and NK cell activation markers had better overall survival. Furthermore, we proved that overexpression of S100A9 in ER+/HER2-cells could improve cocultured NK cell function. CONCLUSION: In conclusion, the study we presented demonstrated that NK cells in ER+/HER2-BC were hypofunctional, and S100A9 was an important regulator of NK cell function in ER+BC. Our work contributes to elucidate the regulatory networks between cancer cells and NK cells and may provide theoretical basis for novel drug development.

Exploring the regulatory role of FBXL19-AS1 in triple-negative breast cancer through the miR-378a-3p/OTUB2 axis.

The regulatory potential of long noncoding RNA (lncRNA) FBXL19-AS1 has been highlighted in various cancers, but its effect on triple-negative breast cancer (TNBC) remains unclear. Here, we aimed to elucidate the role of FBXL19-AS1 in TNBC and its underlying mechanism. RT-qPCR was employed to detect the expressions of FBXL19-AS1 and miR-378a-3p in tissues and cells. Immunohistochemical staining and western blot were utilized to detect the expression levels of proteins. Cell activities were detected using flow cytometry, CCK-8, and transwell assay. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were deployed to investigate interactions of different molecules. Protein-protein interaction (PPI) network, gene ontology (GO), and Kyoto encyclopedia of genes and genomes (KEGG) pathways were used to analyze the downstream pathway. In vivo xenograft model was conducted to detect the effect of FBXL19-AS1 on tumor growth. FBXL19-AS1 was overexpressed in TNBC tissues and cell lines compared with counterparts. FBXL19-AS1 knockdown suppressed TNBC cell activities, whereas its overexpression exhibited the opposite effect. Mechanistically, FBXL19-AS1 was found to interact with miR-378a-3p. Further analysis revealed that miR-378a-3p exerted tumor-suppressive effects in TNBC cells. Additionally, miR-378a-3p targeted and downregulated the expression of ubiquitin aldehyde binding 2 (OTUB2), a deubiquitinase associated with TNBC progression. In vivo experiments substantiated the inhibitory effects of FBXL19-AS1 knockdown on TNBC tumorigenesis, and a miR-378a-3p inhibitor partially rescued these effects. The downstream pathway of the miR-378a-3p/OTUB2 axis was explored, revealing connections with proteins involved in modifying other proteins, removing ubiquitin molecules, and influencing signaling pathways, including the Hippo signaling pathway. Western blot analysis confirmed changes in YAP and TAZ expression levels, indicating a potential regulatory network. In summary, FBXL19-AS1 promotes exacerbation in TNBC by suppressing miR-378a-3p, leading to increased OTUB2 expression. The downstream mechanism may be related to the Hippo signaling pathway. These findings propose potential therapeutic targets for TNBC treatment.

ASS1 inhibits triple-negative breast cancer by regulating PHGDH stability and de novo serine synthesis.

Argininosuccinate synthase (ASS1), a critical enzyme in the urea cycle, acts as a tumor suppressor in many cancers. To date, the anticancer mechanism of ASS1 has not been fully elucidated. Here, we found that phosphoglycerate dehydrogenase (PHGDH), a key rate-limiting enzyme in serine synthesis, is a pivotal protein that interacts with ASS1. Our results showed that ASS1 directly binds to PHGDH and promotes its ubiquitination-mediated degradation to inhibit serine synthesis, consequently suppressing tumorigenesis. Importantly, the tumor suppressive effects of ASS1 were strongly abrogated by PHGDH knockout. In addition, ASS1 knockout and knockdown partially rescued cell proliferation when serine and glycine were depleted, while the inhibitory effect of ASS1 overexpression on cell proliferation was restored by the addition of serine and glycine. These findings unveil a novel role of ASS1 and suggest that the ASS1/PHGDH serine synthesis pathway is a promising target for cancer therapy.

In vitro study on anti-proliferative and anti-cancer activity of picrosides in triple-negative breast cancer.

Picrorhiza kurroa, an "Indian gentian," a known Himalayan medicinal herb with rich source of phytochemicals like picrosides I, II, and other glycosides, has been traditionally used for the treatment of liver and respiratory ailments. Picrosides anti-proliferative, anti-oxidant, anti-inflammatory and other pharmacological properties were evaluated in treating triple-negative breast cancer (TNBC). Picroside I and II were procured from Sigma-Aldrich and were analyzed for anti-cancer activity in triple-negative breast cancer (MDA-MB-231) cells. Cell viability was analyzed using MTT and trypan blue assays. Apoptosis was analyzed through DNA fragmentation and Annexin V/PI flow cytometric analysis. Wound healing and cell survival assays were employed to determine the inhibition of invasion capacity and anti-proliferative activity of picrosides in MDA-MB-231 cells. Measurement of intracellular ROS was studied through mitochondrial membrane potential assessment using DiOC6 staining for anti-oxidant activity of picrosides in MDA-MB-231 cells. Both Picroside I and II have shown decreased cell viability of MDA-MB-231 cells with increasing concentrations. IC50 values of 95.3 µM and 130.8 µM have been obtained for Picroside I and II in MDA-MB-231 cells. Early apoptotic phase have shown an increase of 20% (p < 0.05) with increasing concentrations (0, 50, 75, and 100 µM) of Picroside I and 15% (p < 0.05) increase with Picroside II. Decrease in mitochondrial membrane potential of 2-2.5-fold (p < 0.05) was observed which indicated decreased reactive oxygen species (ROS) generation with increasing concentrations of Picroside I and II. An increasing percentage of 70-80% (p < 0.05) cell population was arrested in G0/G1 phase of cell cycle after Picroside I and II treatment in cancer cells. Our results suggest that Picroside I and II possess significant anti-proliferative and anti-cancer activity which is mediated by inhibition of cell growth, decreased mitochondrial membrane potential, DNA damage, apoptosis, and cell cycle arrest. Therefore, Picroside I and II can be developed as a potential anti-cancer drug of future and further mechanistic studies are underway to identify the mechanism of anti-cancer potential.

Regulation of cellular and molecular markers of epithelial-mesenchymal transition by Brazilin in breast cancer cells.

Breast cancer is the most common invasive neoplasm and the leading cause of cancer death in women worldwide. The main cause of mortality in cancer patients is invasion and metastasis, where the epithelial-mesenchymal transition (EMT) is a crucial player in these processes. Pharmacological therapy has plants as its primary source, including isoflavonoids. Brazilin is an isoflavonoid isolated from Haematoxilum brasiletto that has shown antiproliferative activity in several cancer cell lines. In this study, we evaluated the effect of Brazilin on canonical markers of EMT such as E-cadherin, vimentin, Twist, and matrix metalloproteases (MMPs). By Western blot, we evaluated E-cadherin, vimentin, and Twist expression and the subcellular localization by immunofluorescence. Using gelatin zymography, we determined the levels of secretion of MMPs. We used Transwell chambers coated with matrigel to determine the in vitro invasion of breast cancer cells treated with Brazilin. Interestingly, our results show that Brazilin increases 50% in E-cadherin expression and decreases 50% in vimentin and Twist expression, MMPs, and cell invasion in triple-negative breast cancer (TNBC) MDA-MB-231 and to a lesser extend in MCF7 ER+ breast cancer cells. Together, these findings position Brazilin as a new molecule with great potential for use as complementary or alternative treatment in breast cancer therapy in the future.

Estetrol/GPER/SERPINB2 transduction signaling inhibits the motility of triple-negative breast cancer cells.

BACKGROUND: Estetrol (E4) is a natural estrogen produced by the fetal liver during pregnancy. Due to its favorable safety profile, E4 was recently approved as estrogenic component of a new combined oral contraceptive. E4 is a selective ligand of estrogen receptor (ER)α and ERß, but its binding to the G Protein-Coupled Estrogen Receptor (GPER) has not been described to date. Therefore, we aimed to explore E4 action in GPER-positive Triple-Negative Breast Cancer (TNBC) cells. METHODS: The potential interaction between E4 and GPER was investigated by molecular modeling and binding assays. The whole transcriptomic modulation triggered by E4 in TNBC cells via GPER was explored through high-throughput RNA sequencing analyses. Gene and protein expression evaluations as well as migration and invasion assays allowed us to explore the involvement of the GPER-mediated induction of the plasminogen activator inhibitor type 2 (SERPINB2) in the biological responses triggered by E4 in TNBC cells. Furthermore, bioinformatics analysis was aimed at recognizing the biological significance of SERPINB2 in ER-negative breast cancer patients. RESULTS: After the molecular characterization of the E4 binding capacity to GPER, RNA-seq analysis revealed that the plasminogen activator inhibitor type 2 (SERPINB2) is one of the most up-regulated genes by E4 in a GPER-dependent manner. Worthy, we demonstrated that the GPER-mediated increase of SERPINB2 is engaged in the anti-migratory and anti-invasive effects elicited by E4 in TNBC cells. In accordance with these findings, a correlation between SERPINB2 levels and a good clinical outcome was found in ER-negative breast cancer patients. CONCLUSIONS: Overall, our results provide new insights into the mechanisms through which E4 can halt migratory and invasive features of TNBC cells.

[Study of metal organic framework with siRNA for overcoming matrix barrierin breast cancer].

Objective: This study aimed to develop a new delivery strategy that utilized metal organic framework (MOF) loaded with small-interfering RNA (siRNA) targeting ITGAV to overcome tumor matrix barrier, and thus enhance drug penetration and immune accessibility in breast cancer. Methods: MOF@siITGAV particles were constructed and characterized. The uptake of MOF@siITGAV in breast cancer cell line 4T1 was observed by the cellular uptake assay. The toxicity of MOF@siITGAV was detected by cell counting kit 8 (CCK-8). The blank control group, naked siITGAV group and MOF@siITGAV group were set. Real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) and Western blot were used to detect the expressions of ITGAV. The level of transforming growth factor ß1 (TGF-ß1) in the cell culture medium was detected by enzyme-linked immunosorbent assay (ELISA). The penetration of MOF@siITGAV in 4T1 cells was tested by constructing 3D spheroids. Mouse models of triple negative breast cancer were established. The effect of MOF@siITGAV on the growth of transplanted tumors and main organs was verified. Imminohistochemical (IHC) was used to test the expression of collagen and CD8. Results: MOF@siITGAV particles were constructed with sizes of (198.0±3.3) nm and zeta potential of -(20.2±0.4) mV. MOF@siITGAV could be engulfed by 4T1 cells and triggered to release siRNA. Compared to the blank control group, the expression of ITGAV in the MOF@siITGAV group [(46.5±11.3)%] and the naked siITGAV group [(109.9±19.0)%] was lower. TGF-ß1 in the cell culture medium of the blank control group, naked siITGAV group, and MOF@siITGAV group was (474.5±34.4) pg/ml, (437.2±16.5) pg/ml, and (388.4±14.4) pg/ml, respectively. MOF@siITGAV could better penetrate into 4T1 spheroids and exhibit no obvious toxicity. The cell viability was (99.7±3.5)%, (98.2±5.2)%, (97.3±6.6)%, (92.1±8.1)%, and (92.4±4.1)%, respectively, after MOF@siITGAV treatment with the concentration of 0, 10, 20, 40, 80, and 160 µg/ml, respectively, for 24 h. The tumor growth in the MOF@siITGAV group was suppressed significantly. After 15-day treatment, the tumor volume of the MOF@siITGAV group was (135.3±41.9) mm3, smaller than that of the blank control group [(691.1±193.0) mm3] (P=0.025). The expression of collagen and the number of CD8 positive cells of the MOF@siITGAV group were lower than those of the other two groups. No significant abnormalities were observed in the main organs of mice. Conclusions: Targeting the integrinαv on the surface of cancer cells could destroy extracellular matrix, improve drug delivery, and increase immune infiltration.

Transcriptomics Studies Reveal Functions of Transglutaminase 2 in Breast Cancer Cells Using Membrane Permeable and Impermeable Inhibitors.

Transglutaminase 2 (TG2) performs many functions both under physiological and pathological conditions. In cancer, its expression is associated with aggressiveness, propensity to epithelial-mesenchymal transition, and metastasis. Since TG2 performs key functions both outside and inside the cell, using inhibitors with different membrane permeability we analyzed the changes in the transcriptome induced in two triple-negative cell lines (MDA-MB-436 and MDA-MB-231) with aggressive features. By characterizing pathways and gene networks, we were able to define the effects of TG2 inhibitors (AA9, membrane-permeable, and NCEG2, impermeable) in relation to the roles of the enzyme in the intra- and extracellular space within the context of breast cancer. The deregulated genes revealed p53 and integrin signaling to be the common pathways with some genes showing opposite changes in expression. In MDA-MB-436, AA9 induced apoptosis, modulated cadherin, Wnt, gastrin and cholecystokinin receptors (CCKR) mediated signaling, with RHOB and GNG2 playing significant roles, and affected the Warburg effect by decreasing glycolytic enzymes. In MDA-MB-231 cells, AA9 strongly impacted HIF-mediated hypoxia, including AKT and mTOR pathway. These effects suggest an anti-tumor activity by blocking intracellular TG2 functions. Conversely, the use of NCEG2 stimulated the expression of ATP synthase and proteins involved in DNA replication, indicating a potential promotion of cell proliferation through inhibition of extracellular TG2. To effectively utilize these molecules as an anti-tumor strategy, an appropriate delivery system should be evaluated to target specific functions and avoid adverse effects. Additionally, considering combinations with other pathway modulators is crucial.

Diagnostic utility and sensitivities of matrix Gla protein (MGP), TRPS1 and GATA3 in breast cancer: focusing on metastatic breast cancer, invasive breast carcinoma with special features, and salivary gland-type tumours.

Matrix Gla protein (MGP) and trichorhinophalangeal syndrome type 1 (TRPS1) have recently emerged as novel breast-specific immunohistochemical (IHC) markers, particularly for triple-negative breast cancer (TNBC) and metaplastic carcinoma. The present study aimed to validate and compare the expression of MGP, TRPS1 and GATA binding protein 3 (GATA3) in metastatic breast carcinoma (MBC), invasive breast carcinoma (IBC) with special features, including special types of invasive breast carcinoma (IBC-STs) and invasive breast carcinoma of no special type with unique features, and mammary and non-mammary salivary gland-type tumours (SGTs). Among all enrolled cases, MGP, TRPS1 and GATA3 had comparable high positivity for ER/PR-positive (p=0.148) and HER2-positive (p=0.310) breast carcinoma (BC), while GATA3 positivity was significantly lower in TNBC (p<0.001). Similarly, the positive rates of MGP and TRPS1 in MBCs (99.4%), were higher than in GATA3 (90.9%, p<0.001). Among the IBC-STs, 98.4% of invasive lobular carcinomas (ILCs) were positive for all three markers. Among neuroendocrine tumours (NTs), all cases were positive for TRPS1 and GATA3, while MGP positivity was relatively low (81.8%, p=0.313). In the neuroendocrine carcinoma (NC) subgroup, all cases were positive for GATA3 and MGP, while one case was negative for TRPS1. All carcinomas with apocrine differentiation (APOs) were positive for GATA3 and MGP, while only 60% of the cases demonstrated moderate staining for TRPS1. Among mammary SGTs, MGP demonstrated the highest positivity (100%), followed by TRPS1 (96.0%) and GATA3 (72.0%). Positive staining for these markers was also frequently observed in non-mammary SGTs. Our findings further validate the high sensitivity of MGP and TRPS1 in MBCs, IBC-STs, and breast SGTs. However, none of these markers are capable of distinguishing between mammary and non-mammary SGTs.

Novel combinatorial autophagy inhibition therapy for triple negative breast cancers.

BACKGROUND: Triple negative breast cancer (TNBC) has the worst prognosis among breast cancer subtypes. It is characterized by lack of estrogen, progesterone and human epidermal growth factor 2 receptors, and thus, have limited therapeutic options. Autophagy has been found to be correlated with poor prognosis and aggressive behaviour in TNBC. This study aimed to target autophagy in TNBC via a novel approach to inhibit TNBC progression. METHODS: Immunoblotting and confocal microscopy were carried out to examine the effect of tumor microenvironmental stressors on autophagy. Cellular proliferation and migration assays were used to test the effect of different autophagy inhibitors and standard chemotherapy alone or in combination. In vivo xenograft mouse model was utilized to assess the effect of autophagy inhibitors alone or in combination with Paclitaxel. High resolution mass spectrometry based proteomic analysis was performed to explore the mechanisms behind chemoresistance in TNBC. Lastly, immunohistochemistry was done to assess the correlation between autophagy related proteins and clinical characteristics in TNBC tissue specimens. RESULTS: Metabolic stressors were found to induce autophagy in TNBC cell lines. Autophagy initiation inhibitors, SAR405 and MRT68921, showed marked synergy in their anti-proliferative activity in both chemosensitive and chemoresistant TNBC cell models. Paradoxically, positive expression of autophagosome marker LC3 was shown to be associated with better overall survival of TNBC patients. CONCLUSION: In this study, a novel combination between different autophagy inhibitors was identified which inhibited tumor cell proliferation in both chemosensitive and chemoresistant TNBC cells and could result in development of a novel treatment modality against TNBC.

Single cell lineage tracing reveals clonal dynamics of anti-EGFR therapy resistance in triple negative breast cancer.

BACKGROUND: Most primary Triple Negative Breast Cancers (TNBCs) show amplification of the Epidermal Growth Factor Receptor (EGFR) gene, leading to increased protein expression. However, unlike other EGFR-driven cancers, targeting this receptor in TNBC yields inconsistent therapeutic responses. METHODS: To elucidate the underlying mechanisms of this variability, we employ cellular barcoding and single-cell transcriptomics to reconstruct the subclonal dynamics of EGFR-amplified TNBC cells in response to afatinib, a tyrosine kinase inhibitor (TKI) that irreversibly inhibits EGFR. RESULTS: Integrated lineage tracing analysis revealed a rare pre-existing subpopulation of cells with distinct biological signature, including elevated expression levels of Insulin-Like Growth Factor Binding Protein 2 (IGFBP2). We show that IGFBP2 overexpression is sufficient to render TNBC cells tolerant to afatinib treatment by activating the compensatory insulin-like growth factor I receptor (IGF1-R) signalling pathway. Finally, based on reconstructed mechanisms of resistance, we employ deep learning techniques to predict the afatinib sensitivity of TNBC cells. CONCLUSIONS: Our strategy proved effective in reconstructing the complex signalling network driving EGFR-targeted therapy resistance, offering new insights for the development of individualized treatment strategies in TNBC.

Synergistic effect of human uterine cervical mesenchymal stem cell secretome and paclitaxel on triple negative breast cancer.

BACKGROUND: Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer and, despite its adverse effects, chemotherapy is the standard systemic treatment option for TNBC. Since, it is of utmost importance to consider the combination of different agents to achieve greater efficacy and curability potential, MSC secretome is a possible innovative alternative. METHODS: In the present study, we proposed to investigate the anti-tumor effect of the combination of a chemical agent (paclitaxel) with a complex biological product, secretome derived from human Uterine Cervical Stem cells (CM-hUCESC) in TNBC. RESULTS: The combination of paclitaxel and CM-hUCESC decreased cell proliferation and invasiveness of tumor cells and induced apoptosis in vitro (MDA-MB-231 and/or primary tumor cells). The anti-tumor effect was confirmed in a mouse tumor xenograft model showing that the combination of both products has a significant effect in reducing tumor growth. Also, pre-conditioning hUCESC with a sub-lethal dose of paclitaxel enhances the effect of its secretome and in combination with paclitaxel reduced significantly tumor growth and even allows to diminish the dose of paclitaxel in vivo. This effect is in part due to the action of extracellular vesicles (EVs) derived from CM-hUCESC and soluble factors, such as TIMP-1 and - 2. CONCLUSIONS: In conclusion, our data demonstrate the synergistic effect of the combination of CM-hUCESC with paclitaxel on TNBC and opens an opportunity to reduce the dose of the chemotherapeutic agents, which may decrease chemotherapy-related toxicity.

The incorporation of acetylated LAP-TGF-ß1 proteins into exosomes promotes TNBC cell dissemination in lung micro-metastasis.

Triple-negative breast cancer (TNBC) stands as the breast cancer subtype with the highest recurrence and mortality rates, with the lungs being the common site of metastasis. The pulmonary microenvironment plays a pivotal role in the colonization of disseminated tumor cells. Herein, this study highlights the crucial role of exosomal LAP-TGF-ß1, the principal form of exosomal TGF-ß1, in reshaping the pulmonary vascular niche, thereby facilitating TNBC lung metastasis. Although various strategies have been developed to block TGF-ß signaling and have advanced clinically, their significant side effects have limited their therapeutic application. This study demonstrates that in lung metastatic sites, LAP-TGF-ß1 within exosomes can remarkably reconfigure the pulmonary vascular niche at lower doses, bolstering the extravasation and colonization of TNBC cells in the lungs. Mechanistically, under the aegis of the acetyltransferase TIP60, a non-canonical KFERQ-like sequence in LAP-TGF-ß1 undergoes acetylation at the K304 site, promoting its interaction with HSP90A and subsequent transport into exosomes. Concurrent inhibition of both HSP90A and TIP60 significantly diminishes the exosomal burden of LAP-TGF-ß1, presenting a promising therapeutic avenue for TNBC lung metastasis. This study not only offers fresh insights into the molecular underpinnings of TNBC lung metastasis but also lays a foundation for innovative therapeutic strategies.

Upregulation of FGF9 and NOVA1 in cancer-associated fibroblasts promotes cell proliferation, invasion and migration of triple negative breast cancer.

Cancer-associated fibroblasts (CAFs) play a pivotal role in cancer progression. This study aimed to explore the roles of CAFs-derived Fibroblast growth factor 9 (FGF9) and Neuro-oncological ventral antigen 1 (NOVA1) in triple negative breast cancer (TNBC) progression. MDA-MB-231 and BT-549 cells were cocultured with CAF conditioned-medium (CAF-CM) or normal fibroblasts conditioned-medium (NF-CM). MTT, EdU, colony formation, wound healing, transwell migration, and invasion assays were employed to determine cell proliferation, migration and invasion, respectively. Western blot and RT-qPCR were carried out to examine the protein and mRNA expression of FGF9 and NOVA1. Xenograft tumor experiments were conducted to evaluate the effects of CAFs, FGF9, and NOVA1 on tumor growth in vivo. Our results showed that CAFs significantly promoted the proliferation, invasion, and migration of TNBC cells. FGF9 and NOVA1 were significantly upregulated in TNBC CAFs, tissues and cells. CAF-CM also could increase the expression of FGF9 and NOVA1 in TNBC cells. Knockdown of FGF9 or NOVA1 could hamper cell proliferation, invasion, migration, and EMT of TNBC cells. Moreover, CAFs with FGF9/NOVA1 knockdown also could inhibit TNBC progression. Besides, CAFs significantly accelerated tumor growth in vivo, which was blocked by FGF9/NOVA1 knockdown in nude mice. In conclusion, our results indicated the tumor-promoting role of CAFs in TNBC progression. FGF9 and NOVA1 upregulation in CAFs induced cell proliferation, migration and invasion in vitro, and facilitated tumor growth in vivo in TNBC development.