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This study presents the use of nanoscale covalent organic frameworks (nCOFs) conjugated with tumor-targeting peptides for the targeted therapy of triple-negative breast cancer (TNBC). While peptides have previously been used for targeted delivery, their conjugation with COFs represents an innovative approach in this field. In particular, we have developed alkyne-functionalized nCOFs chemically modified with cyclic RGD peptides (Alkyn-nCOF-cRGD). This configuration is designed to specifically target αvß3 integrins that are overexpressed in TNBC cells. These nCOFs exhibit excellent biocompatibility and are engineered to selectively disintegrate under acidic conditions, allowing for precise and localized drug release in tumor environment. Doxorubicin, a chemotherapeutic agent, has been encapsulated in these nCOFs with high loading efficiency. The therapeutic potential of Alkyn-nCOF-cRGD has been demonstrated in vitro and in vivo models. It shows significantly improved drug uptake and targeted cell death in TNBC, highlighting the efficacy of receptor-mediated endocytosis and pH-controlled drug release. This strategy leverages the unique properties of nCOFs with targeted drug delivery to achieve significant advances in personalized cancer therapy and set a new standard for precision chemotherapeutic delivery.

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Triple-negative breast cancer is aggressive and challenging to treat because of a lack of targets and heterogeneity among tumors. A paramount factor in the mortality from breast cancer is metastasis, which is driven by genetic and phenotypic alterations that drive epithelial-mesenchymal transition, stemness, survival, migration and invasion. Many genetic and epigenetic mechanisms have been identified in triple-negative breast cancer that drive these metastatic phenotypes; however, this knowledge has not yet led to the development of effective drugs for metastatic triple-negative breast cancer (mTNBC). One that may not have received enough attention in the literature is post-translational regulation of broad sets of cancer-related genes through inhibitory microRNAs and the complex competitive endogenous RNA (ceRNA) regulatory networks they are influenced by. This field of study and the resulting knowledge regarding alterations in these networks is coming of age, enabling translation into clinical benefit for patients. Herein, we review metastatic triple-negative breast cancer (mTNBC), the role of ceRNA network regulation in metastasis (and therefore clinical outcomes), potential approaches for therapeutic exploitation of these alterations, knowledge gaps and future directions in the field.

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The complex heterogeneity of tumor microenvironment (TME) of triple-negative breast cancer (TNBC) presents a significant obstacle to cytotoxic immune response and successful treatment, building up one of the most hostile oncological phenotypes. Among the most abundant TME components, tumor-associated macrophages (TAMs) have pivotal pro-tumoral functions, involving discordant roles for the nuclear factor kappa-B (NF-κB) transcription factors and directing to higher levels of pathway complexity. In both resting macrophages and TAMs, we recently revealed the existence of the uncharacterized NF-κB p65/p52 dimer. In the present study, we demonstrated its enhanced active nuclear localization in TAMs and validated selected immune target genes as directly regulated by dimer binding on DNA sequences. We demonstrated by ChIP-qPCR that p65/p52 enrichment on HSPG2 and CSF-1 regulatory regions is strictly dependent on macrophage polarization and tumor environment. Our data provide novel mechanisms of transcriptional regulation in TAMs, orchestrated by the varied and dynamic nature of NF-κB combinations, which needs to be considered when targeting this pathway in cancer therapies. Our results offer p65/p52, together with identified regulatory regions on genes impacting macrophage behavior and tumor biology, as novel molecular targets for TNBC, aimed at modulating TAMs functions towards anti-tumoral phenotypes and thus improving cancer treatment outcomes.

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Cancer stem cells (CSCs) have the potential to self-renew and induce cancer, which may contribute to a poor prognosis by enabling metastasis, recurrence, and therapy resistance. Hence, this study was performed to identify the association between CSC-related genes and triple-negative breast cancer (TNBC) development. Stemness gene sets were downloaded from StemChecker. Based on the online databases, a consensus clustering algorithm was conducted for unsupervised classification of TNBC samples. The variations between subtypes were assessed with regard to prognosis, tumor immune microenvironment (TIME), and chemotherapeutic sensitivity. The stemness-related gene signature was established and random survival forest analysis was employed to identify the core gene for validation experiments and tumor sphere formation assays. 499 patients with TNBC were classified into three subgroups and the Cluster 1 had a better OS than others. After that, WGCNA study was performed to identify genes important for Cluster 1 subtype. Out of all 8 modules, the subtype of Cluster 1 and the yellow module with 103 genes demonstrated the largest positive association. After that, a four-gene stemness-related signature was established. Based on the yellow module, the 39 potential pivotal genes were subjected to the random forest survival analysis to find out the gene that was relatively important for OS. KIF15 was confirmed as the targeted gene by LASSO and random survival forest analyses. In vitro experiments, the downregulation of KIF15 promoted the stemness of TNBC cells. The expression levels of stem cell markers Nanog, SOX2, and OCT4 were found to be elevated in TNBC cell lines after KIF15 inhibition. A stemness-associated risk model was constructed to forecast the clinical outcomes of TNBC patients. The downregulation of KIF15 expression in a subpopulation of TNBC stem cells may promote stemness and possibly TNBC progression.

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Triple-negative breast cancer (TNBC) represents the most formidable subtype of breast cancer, characterized by a notable dearth in targeted therapeutic options. Deciphering the underlying molecular mechanisms of TNBC is pivotal for improving patient outcomes. Recent scientific advancements have spotlighted long non-coding RNAs (lncRNAs) as key players in the genesis, progression, and metastasis of cancers. This review delineates the significant influence of lncRNAs on the advancement, detection, and neoadjuvant chemotherapy efficacy in TNBC, detailing the diverse expression patterns of aberrant lncRNAs. The paper explores the specific mechanisms by which lncRNAs regulate gene expression in both the nucleus and cytoplasm, with a special focus on their involvement in TNBC's post-transcriptional landscape. Thorough investigations into TNBC-associated lncRNAs not only forge new avenues for early diagnosis and potent treatment strategies but also highlight these molecules as promising therapeutic targets, heralding an era of personalized and precision medicine in TNBC management.

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Breast cancer emerges as one of the most prevalent malignancies in women, its incidence showing a concerning upward trend. Among the diverse array of breast cancer subtypes, triple-negative breast cancer (TNBC) assumes notable significance, due to lack of estrogen, progesterone, and HER-2 receptors. More focus has to be placed on creating effective therapy due to the high prevalence and rising incidence of TNBC. Currently, conventional passive treatments have several drawbacks that have not yet been resolved. On the other hand, as innovative immunotherapy approaches, cancer vaccines have offered promising prospects in combatting advanced stages of TNBC. Therefore, the main objective of this study was to utilize WT1 and NY-ESO-1 antigenic proteins in designing a multiepitope vaccine against TNBC. Initially, to generate robust immune responses, we identified antigenic epitopes of both proteins and assessed their immunogenicity. In order to reduce junctional immunogenicity, promiscuous epitopes were joined using the suitable adjuvant (50S ribosomal L7/L12 protein) and incorporated appropriate linkers (GPGPG, AAY, and EAAAK). The best predicted 3D model was refined and validated to achieve an excellent 3D model. Molecular docking analysis and dynamic simulation were conducted to demonstrate the structural stability and integrity of the vaccine/TLR-4 complex. Finally, the vaccine was cloned into the vector pET28 (+). Thus, analysis of the constructed vaccine through immunoinformatics indicates its capability to elicit robust humoral and cellular immune responses in the targeted organism. As such, it holds promise as a therapeutic weapon against TNBC and may open doors for further research in the field.

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Background: The majority of small-sized (<3 cm) triple-negative breast cancer (TNBC) exhibit smooth margins upon palpation and are often oval or rounded masses. Distinguishing these masses preoperatively from fibroadenomas (FAs) would be very meaningful for clinical practice. The aim of our study was to evaluate the magnetic resonance imaging (MRI) appearance of TNBC and differentiate it from FAs. Methods: In this retrospective single-center study, we included 37 patients with TNBCs and 36 patients with FAs who underwent breast MRI. We employed the χ2 test and t-test to compare the differences in morphological features, dynamic contrast-enhanced MRI (DCE-MRI) parameters, and apparent diffusion coefficient (ADC) values between the two groups. Additionally, we constructed non-parametric receiver operating characteristic (ROC) curves using ADC values, with pathological results serving as the gold standard. Results: A total of 37 TNBC lesions and 39 FA lesions were included in the final analysis. TNBCs exhibited more frequent irregular shape, irregular margins, peritumoral edema, fast enhancement in the initial phase, rim enhancement, and time-signal intensity curve (TIC) type III compared to FAs (all P<0.05). Conversely, low-signal segregation in T2-weighted imaging (T2WI) and TIC type I were commonly found in FAs. The mean ADC value of TNBCs was significantly lower than that of FAs [(1.104±0.13)×10-3 vs. (1.613±0.16)×10-3 mm2/s, P<0.05]. The cutoff ADC for differentiating TNBCs from FAs was 1.239×10-3 mm2/s, yielding an area under the curve (AUC) of 0.997, a sensitivity of 94.6%, and a specificity of 100%. Conclusions: The morphological presentation of MRI, internal enhancement features of the mass, TIC curves, and ADC values provide valuable differential diagnostic information for TNBC and FA masses with a maximum diameter of less than 3 cm.

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Repurposing drugs offers several advantages, including reduced time and cost compared to developing new drugs from scratch. It leverages existing knowledge about drug safety, dosage, and pharmacokinetics, expediting the process of clinical trials and regulatory approval. Dihydroartemisinin (DHA) is a semi-synthetic and active metabolite of all artemisinin molecules and is FDA-approved for the treatment of malaria. Apart from having anti-malarial properties, DHA also possesses anticancer properties. However, its pharmacological actions are limited by toxicity and solubility problems. To overcome these challenges and enhance its anticancer effectiveness, we designed an exosomal formulation of DHA. We isolated exosomes from bovine milk using differential ultracentrifugation and loaded DHA using sonication. Scanning and transition electron microscopy revealed a size of roughly 100 nm, with a spherical shape. Furthermore, in pH 7.4 and 5.5, the exosomes exhibited burst release followed by sustained release. Multiple in vitro cell culture tests demonstrated that Exo-DHA exhibited enhanced anticancer activity, including cytotoxicity, cellular uptake, generation of reactive oxygen species (ROS), disruption of mitochondrial membrane potential, and inhibition of colony formation. Additional evidence supporting Exo-DHA's anti-migration ability came from transwell migration and scratch assays. Based on these results, it was concluded that the anticancer efficacy of DHA was improved when loaded into bovine milk-derived exosomes. While the in vitro results are encouraging, more in vivo testing in suitable animal models and biochemical marker analysis are warranted.

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c-MYC is overexpressed in 70% of human cancers, including triple-negative breast cancer (TNBC), yet there is no clinically approved drug that directly targets it. Here, we engineered the mRNA-stabilizing poly U sequences within the 3'UTR of c-MYC to specifically destabilize and promote the degradation of c-MYC transcripts. Interestingly, the engineered derivative outcompetes the endogenous overexpressed c-MYC mRNA, leading to reduced c-MYC mRNA and protein levels. The iron oxide nanocages (IO-nanocages) complexed with MYC-destabilizing constructs inhibited primary and metastatic tumors in mice bearing TNBC and significantly prolonged survival by degrading the c-MYC-STAT5A/B-PD-L1 complexes that drive c-MYC-positive TNBC. Taken together, we have described a novel therapy for c-MYC-driven TNBC and uncovered c-MYC-STAT5A/B-PD-L1 interaction as the target.

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BACKGROUND: Squama Manis is a valuable traditional Chinese medicine with a long history of medicinal use in the treatment of breast-related diseases. However, owing to the excessive exploitation and utilization of the resources, Squama Manis has been included in the list of rare and endangered wild animals. The conservation of the resources of Squama Manis and continuing its clinical application has become an urgent problem, and the search for small-molecule substitutes for Squama Manis is an effective way to achieve this goal. Previous studies have identified PA3264 as a possible active ingredient in Squama Manis. In this study, we systematically investigated the pharmacological effects and mechanisms of PA3264 in the treatment of triple-negative breast cancer (TNBC), a representative breast-related disease. METHODS: Cell viability and colony formation assays were performed after treatment with the target dipeptide PA3264 in vitro. Next, 4T1 orthotopic tumors and humanized PBMC-CDX mouse models were generated to examine the antitumor effect of PA3264 in vivo. Transcriptome sequencing and molecular docking experiments were performed to predict pathways to function. Western blotting and quantitative real-time PCR were used to validate the molecular mechanisms underlying the anticancer effects of PA3264. RESULTS: PA3264 significantly inhibited cell viability and migration of breast cancer cells in vitro. Furthermore, PA3264 suppressed the tumor size and reduced the tumor weight in vivo. Finally, it was verified that PA3264 prevented the progression of breast cancer by inhibiting the PI3K/AKT/NF-κB pathway, causing cell cycle arrest, and promoting apoptosis. CONCLUSIONS: This study elucidated that PA3264 derived from rare and endangered Squama Manis was a novel bioactive peptide for treating triple-negative breast cancer from a scientific research perspective.

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Triple-negative breast cancer (TNBC) has short survival rates. This study aimed to prepare a novel formula of sorafenib, carbon nanotubes (CNTs), and folic acid to be tested as a drug delivery system targeting versus TNBC compared with free sorafenib and to evaluate the formula stability, in vitro pharmacodynamic, and in vivo pharmacokinetic properties. The formula preparation was done by the synthesis of polyethylene glycol bis amine linker, CNT PEGylation, folic acid attachment, and sorafenib loading. The prepared formula has been characterized using X-ray diffraction, Flourier-transform infrared, 1HNMR, UV, high resolution-transmission electron microscope, field emission scanning electron microscopy, and Zeta potential. In vitro studies included drug release determination, MTT assay, flow cytometry to determine the apoptotic stage with percent, cell cycle analysis, and apoptotic marker assays for caspase-3, 8, 9, cytochrome c, and BCL-2. The in vivo study was performed to determine bioavailability and half-life in rats. The in vitro MTT antiproliferative assay revealed that the formula was threefold more cytotoxic toward TNBC cells than free sorafenib, and the flow cytometry showed a significant increase in apoptosis and necrosis. The formula has a greater inhibitory effect on BCL-2 and a lessening effect on cytochrome c and caspases 3, 8, and 9 than free sorafenib. In vivo experiments proved that our novel formula was superior to free sorafenib by increasing bioavailability by eight times and prolonging the half-life by three times. These results confirmed the successful preparation of the desired formula with better pharmacodynamic and pharmacokinetic properties. These promising results may show a novel therapeutic strategy for TNBC patients.

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The study investigated the effect of Compound Shougong Powder(CSGP) on the biological functions of triple-negative breast cancer(TNBC) cells and whether its mechanism of action was related to the epithelial-mesenchymal transition(EMT) signaling pathway. TNBC cells(MDA-MB-231 and BT-549) were treated with different concentrations of CSGP-containing serum. MTS assay was used to detect the effect of CSGP on the proliferation of TNBC cells. The EdU staining was used to detect the effect of CSGP on the proliferation of TNBC cells. Flow cytometry was used to examine the impact of CSGP on apoptosis of TNBC cells. Wound-healing and Transwell assays were used to evaluate the effects of different concentrations of CSGP on the migration and invasion capabilities of TNBC cells. RNA sequencing technology was utilized to elucidate its mechanism. Subsequently, qRT-PCR was performed to measure the mRNA expression levels of E-cadherin, N-cadherin, Slug, Snail, Vimentin, Twist, Zinc finger E-box-Binding homeobox 1(Zeb1), and Zinc finger E-box-Binding homeobox 2(Zeb2). Western blot was used to assess the protein expression levels of Slug, Vimentin, and E-cadherin. After intervention with CSGP, the proliferation of MDA-MB-231 and BT-549 cells significantly decreased, while the apoptosis rate markedly increased. The expression levels of the epithelial marker protein E-cadherin significantly increased, while the expression levels of the EMT-related transcription factors Slug and Vimentin showed a decrease. In conclusion, CSGP inhibits the EMT, thereby suppressing the malignant progression of TNBC.

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Triple-negative breast cancer (TNBC) represents a major therapeutic challenge due to its heterogeneous and aggressive phenotype, and limited target-specific treatment options. The trophoblast cell surface antigen (Trop-2), a transmembrane glycoprotein overexpressed in various cancers, has emerged as a promising target for TNBC. Sacituzumab govitecan (SG), an antibody-drug conjugate (ADC) that targets Trop-2, has recently entered treatment algorithms for advanced and metastatic TNBC, independently from Trop-2 expression status, with manageable toxicity. Despite the impressive results, questions remain unsolved regarding its efficacy, safety profile, and Trop-2 biological role in cancer. Currently, Trop-2 cannot be designated as a predictive biomarker in SG treatment, albeit its expression correlates with disease outcome, yet its levels are not uniform across all TNBCs. Additionally, data regarding Trop-2 expression variations in primary and metastatic sites, and its interplay with other biomarkers are still ambiguous but mandatory in light of future applications of SG in other indications and settings. This poses the questions of a careful evaluation of the efficacy and toxicity profile of SG in such early stages of disease, and in personalized and combinatorial strategies. Research and clinical data are mandatory to address SG drawbacks and minimize its benefits, to realize its full potential as therapeutic agent in different epithelial tumors.

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Breast cancer (BC) is a significant cause of cancer-related mortality, and triple-negative breast cancer (TNBC) is a particularly aggressive subtype associated with high mortality rates, especially among younger females. TNBC poses a considerable clinical challenge due to its aggressive tumor behavior and limited therapeutic options. Aberrations within the PI3K/AKT pathway are prevalent in TNBC and correlate with increased therapeutic intervention resistance and poor outcomes. MicroRNAs (miRs) have emerged as crucial PI3K/AKT pathway regulators influencing various cellular processes involved in TNBC pathogenesis. The levels of miRs, including miR-193, miR-4649-5p, and miR-449a, undergo notable changes in TNBC tumor tissues, emphasizing their significance in cancer biology. This review explored the intricate interplay between miR variants and PI3K/AKT signaling in TNBC. The review focused on the molecular mechanisms underlying miR-mediated dysregulation of this pathway and highlighted specific miRs and their targets. In addition, we explore the clinical implications of miR dysregulation in TNBC, particularly its correlation with TNBC prognosis and therapeutic resistance. Elucidating the roles of miRs in modulating the PI3K/AKT signaling pathway will enhance our understanding of TNBC biology and unveil potential therapeutic targets. This comprehensive review aims to discuss current knowledge and open promising avenues for future research, ultimately facilitating the development of precise and effective treatments for patients with TNBC.

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Triple-negative breast cancer (TNBC) is the deadliest form of breast cancer with limited treatment options. The persistence of highly tumorigenic CD44-expressing subpopulation referred to as cancer stem cells (CSCs), endowed with the self-renewal capacity, has been associated with therapeutic resistance, hence clinical relapses. To mitigate these undesired events, targeted immunotherapies using antibody-photoconjugate (APC) or antibody-drug conjugate (ADC), were developed to specifically release cytotoxic payloads within targeted cells overexpressing cognate antigen receptors. Therefore, an αCD44(scFv)-SNAP-tag antibody fusion protein was engineered through genetic fusion of a single-chain antibody fragment (scFv) to a SNAPf-tag fusion protein, capable of self-conjugating with benzylguanine-modified light-sensitive near-infrared (NIR) phthalocyanine dye IRDye700DX (BG-IR700) or the small molecule toxin auristatin-F (BG-AURIF). Binding of the αCD44(scFv)-SNAPf-IR700 photoimmunoconjugate to antigen-positive cells was demonstrated by confocal microscopy and flow cytometry. By switching to NIR irradiation, CD44-expressing TNBC was selectively killed through induced phototoxic activities. Likewise, the αCD44(scFv)-SNAPf-AURIF immunoconjugate was able to selectively accumulate within targeted cells and significantly reduced cell viability through antimitotic activities at nano- to micromolar drug concentrations. This study provides an in vitro proof-of-concept for a future strategy to selectively destroy light-accessible superficial CD44-expressing TNBC tumors and their metastatic lesions which are inaccessible to therapeutic light.

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Metastatic recurrence is still a major challenge in breast cancer treatment. Patients with triple negative breast cancer (TNBC) develop early recurrence and relapse more frequently. Due to the lack of specific therapeutic targets, new targeted therapies for TNBC are urgently needed. Phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway is one of the active pathways involved in chemoresistance and survival of TNBC, being considered as a potential target for TNBC treatment. Our present study identified ticagrelor, an anti-platelet drug, as a pan-PI3K inhibitor with potent inhibitory activity against four isoforms of class I PI3K. At doses normally used in clinic, ticagrelor showed weak cytotoxicity against a panel of breast cancer cells, but significantly inhibited the migration, invasion and the actin cytoskeleton organization of human TNBC MDA-MB-231 and SUM-159PT cells. Mechanistically, ticagrelor effectively inhibited PI3K downstream mTOR complex 1 (mTORC1) and mTORC2 signaling by targeting PI3K and decreased the protein expression of epithelial-mesenchymal transition (EMT) markers. In vivo, ticagrelor significantly suppressed tumor cells lung metastasis in 4T1 tumor bearing BALB/c mice model and experimental lung metastasis model which was established by tail vein injection of GFP-labeled MDA-MB-231 cells. The above data demonstrated that ticagrelor can inhibit the migration and invasion of TNBC both in vitro and in vivo by targeting PI3K, suggesting that ticagrelor, a pan-PI3K inhibitor, might represent a promising therapeutic agent for the treatment of metastatic TNBC.

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BACKGROUND: Lysine methyltransferase 2D (KMT2D) mediates mono-methylation of histone H3 lysine 4 (H3K4me1) in mammals. H3K4me1 mark is involved in establishing an active chromatin structure to promote gene transcription. However, the precise molecular mechanism underlying the KMT2D-mediated H3K4me1 mark modulates gene expression in triple-negative breast cancer (TNBC) progression is unresolved. METHODS AND RESULTS: We recognized Y-box-binding protein 1 (YBX1) as a "reader" of the H3K4me1 mark, and a point mutation of YBX1 (E121A) disrupted this interaction. We found that KMT2D and YBX1 cooperatively promoted cell growth and metastasis of TNBC cells in vitro and in vivo. The expression levels of KMT2D and YBX1 were both upregulated in tumour tissues and correlated with poor prognosis for breast cancer patients. Combined analyses of ChIP-seq and RNA-seq data indicated that YBX1 was co-localized with KMT2D-mediated H3K4me1 in the promoter regions of c-Myc and SENP1, thereby activating their expressions in TNBC cells. Moreover, we demonstrated that YBX1 activated the expressions of c-Myc and SENP1 in a KMT2D-dependent manner. CONCLUSION: Our results suggest that KMT2D-mediated H3K4me1 recruits YBX1 to facilitate TNBC progression through epigenetic activation of c-Myc and SENP1. These results together unveil a crucial interplay between histone mark and gene regulation in TNBC progression, thus providing novel insights into targeting the KMT2D-H3K4me1-YBX1 axis for TNBC treatment. HIGHLIGHTS: YBX1 is a KMT2D-mediated H3K4me1-binding effector protein and mutation of YBX1 (E121A) disrupts its binding to H3K4me1. KMT2D and YBX1 cooperatively promote TNBC proliferation and metastasis by activating c-Myc and SENP1 expression in vitro and in vivo. YBX1 is colocalized with H3K4me1 in the c-Myc and SENP1 promoter regions in TNBC cells and increased YBX1 expression predicts a poor prognosis in breast cancer patients.

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Triple negative breast cancer (TNBC) presents a significant global health concern due to its aggressive nature, high mortality rate and limited treatment options, highlighting the urgent need for targeted therapies. Beauvericin, a bioactive fungal secondary metabolite, possess significant anticancer potential, although its molecular targets in cancer cells remain unexplored. This study has investigated possible molecular targets of beauvericin and its therapeutic insights in TNBC cells. In silico studies using molecular docking and MD simulation predicted the molecular targets of beauvericin. The identified targets included MRP-1 (ABCC1), HDAC-1, HDAC-2, LCK and SYK with average binding energy of -90.1, -44.3, -72.1, -105 and -60.8 KJ/mol, respectively, implying its multifaceted roles in reversing drug resistance, inhibiting epigenetic modulators and oncogenic tyrosine kinases. Beauvericin has significantly reduced the viability of MDA-MB-231 and MDA-MB-468 cells, with IC50 concentrations of 4.4 and 3.9 µM, while concurrently elevating the intracellular ROS by 9.0 and 7.9 folds, respectively. Subsequent reduction of mitochondrial transmembrane potential in TNBC cells, has confirmed the induction of oxidative stress, leading to apoptotic cell death, as observed by flow cytometric analyses. Beauvericin has also arrested cell cycle at G1-phase and impaired the spheroid formation and clonal expansion abilities of TNBC cells. The viability of spheroids was reduced upon beauvericin treatment, exhibiting IC50 concentrations of 10.3 and 6.2 µM in MDA-MB-468 and MDA-MB-231 cells, respectively. In conclusion, beauvericin has demonstrated promising therapeutic potential against TNBC cells through possible inhibition of MRP-1 (ABCC1), HDAC-1, HDAC-2, LCK and SYK.

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Triple-negative breast cancer (TNBC) cells are often resistant to FAS (CD95)-mediated apoptosis, but the underlying molecular mechanism(s) is not fully understood yet. Notably, the expression of the type II transmembrane protein, CD74, is correlated with chemotherapy-resistant and more invasive forms of cancers via unknown mechanisms. Here, we analyzed gene expression pattern of cancer patients and/or patient-derived xenograft (PDX) models and found that mRNA and protein levels of CD74 are highly expressed in TNBC and correlated with cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) properties. Mechanistically, we found that AKT activation is likely critical for maintaining CD74 expression and protein stability to favor its oncogenic functions. Physiologically, epidermal growth factor (EGF) along with CD74 could activate AKT signaling, likely through binding of phosphorylated AKT (S473) to CD74, whereas inhibition of AKT could impair stability of CD74. We also revealed that CD74 binds to FAS and interferes with the intrinsic signaling of FAS-mediated apoptosis. As such, selective targeting of the CD74/FAS complex using the AKT inhibitor along with the CD74-derived peptide could synergistically restore and activate FAS-mediated apoptosis. Therefore, our approach of mobilizing apoptosis pathways likely provides a rationale for TNBC treatment by targeting the CD74/FAS and CD74-AKT axes.