The potential role of breast MRI in evaluation of triple-negative breast cancer and fibroadenoma of less than 3 cm.

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.

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.

A chemical screen identifies PRMT5 as a therapeutic vulnerability for paclitaxel-resistant triple-negative breast cancer.

Paclitaxel-resistant triple negative breast cancer (TNBC) remains one of the most challenging breast cancers to treat. Here, using an epigenetic chemical probe screen, we uncover an acquired vulnerability of paclitaxel-resistant TNBC cells to protein arginine methyltransferases (PRMTs) inhibition. Analysis of cell lines and in-house clinical samples demonstrates that resistant cells evade paclitaxel killing through stabilizing mitotic chromatin assembly. Genetic or pharmacologic inhibition of PRMT5 alters RNA splicing, particularly intron retention of aurora kinases B (AURKB), leading to a decrease in protein expression, and finally results in selective mitosis catastrophe in paclitaxel-resistant cells. In addition, type I PRMT inhibition synergies with PRMT5 inhibition in suppressing tumor growth of drug-resistant cells through augmenting perturbation of AURKB-mediated mitotic signaling pathway. These findings are fully recapitulated in a patient-derived xenograft (PDX) model generated from a paclitaxel-resistant TNBC patient, providing the rationale for targeting PRMTs in paclitaxel-resistant TNBC.

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.

The vitamin D analog EB1089 sensitizes triple-negative breast cancer cells to the antiproliferative effects of antiestrogens.

PURPOSE: Patients bearing estrogen receptor (ER)α-negative breast cancer tumors confront poor prognosis and are typically unresponsive to hormone therapy. Previous studies have shown that calcitriol, the active vitamin D metabolite, can induce ERα expression in ERα-negative cells. EB1089, a calcitriol analog with reduced calcemic effects, exhibits greater potency than calcitriol in inhibiting cancer cell growth. However, the impact of EB1089 on ERα expression in triple-negative breast cancer (TNBC) cells remains unexplored. This study aims to investigate whether EB1089 could induce functional ERα expression in TNBC cell lines, potentially enabling the antiproliferative effects of antiestrogens. MATERIALS AND METHODS: TNBC cell lines HCC1806 and HCC1937 were treated with EB1089, and ERα expression was analyzed using real-time PCR and Western blots. The transcriptional activity of induced ERα was evaluated through a luciferase reporter assay. The antiproliferative effects of tamoxifen and fulvestrant antiestrogens were assessed using the sulforhodamine B assay in the EB1089-treated cells. RESULTS: Our findings indicated that EB1089 significantly induced ERα mRNA and protein expression in TNBC cells. Moreover, EB1089-induced ERα exhibited transcriptional activity and effectively restored the inhibitory effects of antiestrogens, thereby suppressing cell proliferation in TNBC cells. CONCLUSION: EB1089 induced the expression of functional ERα in TNBC cells, restoring the antiproliferative effects of antiestrogens. These results highlight the potential of using EB1089 as a promising strategy for re-establishment of the antiproliferative effect of antiestrogens as a possible management for TNBC. This research lays the foundation for potential advancements in TNBC treatment, offering new avenues for targeted and effective interventions.

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.

SNHG14 promotes triple-negative breast cancer cell proliferation, invasion, and chemoresistance by regulating the ERK/MAPK signaling pathway.

The functional role and molecular mechanisms of small-nucleolar RNA host gene 14 (SNHG14) in triple-negative breast cancer (TNBC) progression remain unclear. The expression levels of SNHG14 in breast cancer samples and cell lines were determined using real-time quantitative polymerase chain reaction. Cell proliferation, migration, and invasion abilities were detected using MTS and transwell assays. By RNA sequencing, differentially expressed genes were identified between the SNHG14 siRNA and the negative control group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were used to predict the targets and pathways regulated by SNHG14. pRAF, pMEK, and pERK expression were measured by western blot. The xenograft model was constructed to access the biological function of SNHG14 in vivo. A minimal patient-derived xenograft model was established to evaluate the sensitivity to chemotherapy drugs. Our data indicated that SNHG14 expression was increased in TNBC tissues and cell lines. SNHG14 knockdown attenuated the proliferation, migration, and invasion abilities of TNBC cells both in vivo and in vitro. High SNHG14 expression was associated with lymph node metastasis and a high Ki67 index. The targets of SNHG14 were mainly enriched in the MAPK signaling pathway. pRAF, pMEK, and pERK expression were downregulated after being transfected with SNHG14 siRNA. Compared with the negative control group, the expression of CACNA1I, DUSP8, FGF17, FGFR4, FOS, PDGFRB, and DDIT3 was increased, and the expression of MKNK1 was decreased in the SNHG14 siRNA group. Minimal patient-derived xenograft model demonstrated that knockdown of SNHG14 enhanced the sensitivity to Docetaxel in vivo. Compared with the DMSO group, the proliferation of Docetaxel-resistant MDA-MB-231 cells was decreased in Dabrafenib, PD184352, and FR180204 treatment groups. SNHG14 knockdown inhibits TNBC progression by regulating the ERK/MAPK signaling pathway, which provides evidence for SNHG14 as a potential target for TNBC therapy.

Integrated machine learning algorithms identify KIF15 as a potential prognostic biomarker and correlated with stemness in triple-negative breast cancer.

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.

The RAL Small G Proteins Are Clinically Relevant Targets in Triple Negative Breast Cancer.

Breast cancer (BC) is the most frequent cancer and second-leading cause of cancer deaths in women in the United States. While RAS mutations are infrequent in BC, triple-negative (TN) and HER2-positive (HER2+) BC both exhibit increased RAS activity. Here, we tested the RAS effectors RALA and RALB, which are overexpressed in BC, as tractable molecular targets in these subtypes. While analysis of the breast cancer patient sample data suggests that the RALs are associated with poor outcome in both TNBC and HER2+ BC, our in vivo and in vitro experimental findings revealed the RALs to be essential in only the TNBC cell lines. While testing the response of the BC cell lines to the RAL inhibitors RBC8 and BQU57, we observed no correlation between drug efficacy and cell line dependency on RAL expression for survival, suggesting that these compounds kill via off-target effects. Finally, we report the discovery of a new small molecule inhibitor, OSURALi, which exhibits strong RAL binding, effectively inhibits RAL activation, and is significantly more toxic to RAL-dependent TNBC cells than RAL-independent HER2+ and normal cell lines. These results support the RALs as viable molecular targets in TNBC and the further investigation of OSURALi as a therapeutic agent.

Advanced Insights into Competitive Endogenous RNAs (ceRNAs) Regulated Pathogenic Mechanisms in Metastatic Triple-Negative Breast Cancer (mTNBC).

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.

Immune checkpoint inhibitor treatment does not impair ovarian or endocrine function in a mouse model of triple negative breast cancer.

Background: Representing 15-20% of all breast cancer cases, triple negative breast cancer (TNBC) is diagnosed more frequently in reproductive-age women and exhibits higher rates of disease metastasis and recurrence when compared with other subtypes. Few targeted treatments exist for TNBC, and many patients experience infertility and endocrine disruption as a result of frontline chemotherapy treatment. While they are a promising option for less toxic therapeutic approaches, little is known about the effects of immune checkpoint inhibitors on reproductive and endocrine function. Results: Our findings in a syngeneic TNBC mouse model revealed that therapeutically relevant immunotherapies targeting PD-1, LAG-3, and TIM-3 had no effect on the quality and abundance of ovarian follicles, estrus cyclicity, or hormonal homeostasis. Similarly, in a tumor-free mouse model, we found that ovarian architecture, follicle abundance, estrus cyclicity, and ovulatory efficiency remain unchanged by PD-1 blockade. Conclusions: Taken together, our results suggest that immunotherapy may be a promising component of fertility-sparing therapeutic regimens for patients that wish to retain ovarian and endocrine function after cancer treatment.

An Investigation of In Vitro Anti-Cancer Efficacy of Dihydroartemisinin-Loaded Bovine Milk Exosomes Against Triple-Negative Breast Cancer.

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.

STC2 suppresses triple-negative breast cancer migration and invasion by inhibition on EMT and promotion on cell apoptosis.

To investigate the effects of higher cellular stanniocalcin 2 (STC2) on suppressing the migration and invasion but promoting the apoptosis of triple-negative breast cancer (TNBC). STC2 in TNBC and the para-carcinoma tissues were analyzed by immunohistochemistry (IHC), while the mRNA level was measured by qPCR. Over-expressing or silencing STC2 was established in MDA-MB-231 cells. Epithelial mesenchymal transition (EMT) related proteins, cell migration, invasion, proliferation and apoptosis were detected. MDA-MB-231 with over-expressing or silencing STC2 were injected into nude mice to formatting tumors, and then EMT related proteins were measured by IHC. Lower STC2 expressed in TNBC tissues than in the para-carcinoma tissues. Silencing STC2 promoted EMT of TNBC cell MDA-MB-231, as well as cell migration, invasion and proliferation, but suppressed MDA-MB-231 apoptosis, while over-expressing STC2 had the opposite results, which might be related to PKC/PI3K/AKT/mTOR pathway. STC2 was the protective gene in TNBC, by suppressing migration and invasion to inhibit MDA-MB-231 cell EMT but promote cell apoptosis, in order to suppress TNBC progression.

Combination of ionizing radiation and 2-thio-6-azauridine induces cell death in radioresistant triple negative breast cancer cells by downregulating CD151 expression.

BACKGROUND: Triple-negative breast cancer (TNBC) represents the most aggressive subtype of breast cancer and is frequently resistant to therapy, ultimately resulting in treatment failure. Clinical trials have demonstrated the potential of sensitizing radiation therapy (RT)-resistant TNBC through the combination of chemotherapy and RT. This study sought to explore the potential of CD151 as a therapy response marker in the co-treatment strategy involving ionizing radiation (IR) and the repurposed antiviral drug 2-Thio-6-azauridine (TAU) for sensitizing RT-resistant TNBC (TNBC/RR). METHODS: The investigation encompassed a variety of assessments, including viability using MTT and LDH assays, cell proliferation through BrdU incorporation and clonogenic assays, cell cycle analysis via flow cytometry, cell migration using wound scratch and Boyden chamber invasion assays, DNA damage assessment through γH2AX analysis, apoptosis evaluation through acridine-orange and ethidium bromide double staining assays, as well as caspase 3 activity measurement using a colorimetric assay. CD151 expression was examined through ELISA, flow cytometry and RT-qPCR. RESULTS: The results showed a significant reduction in TNBC/RR cell viability following co-treatment. Moreover, the co-treatment reduced cell migration, induced apoptosis, downregulated CD151 expression, and increased caspase 3 activity in TNBC/RR cells. Additionally, CD151 was predicted to serve as a therapy response marker for co-treatment with TAU and IR. CONCLUSION: These findings suggest the potential of combination treatment with IR and TAU as a promising strategy to overcome RT resistance in TNBC. Furthermore, CD151 emerges as a valuable therapy response marker for chemoradiotherapy.

Phosphoenolpyruvate carboxykinase-2 (PCK2) is a therapeutic target in triple-negative breast cancer.

PURPOSE: Metabolic rewiring in malignant transformation is often accompanied by altered expression of metabolic isozymes. Phosphoenolpyruvate carboxykinase-2 (PCK2) catalyzes the rate-limiting step of gluconeogenesis and is the dominant isoform in many cancers including triple-negative breast cancer (TNBC). Our goal was to identify small molecule inhibitors of PCK2 enzyme activity. METHODS: We assessed the impact of PCK2 down regulation with shRNA on TNBC cell growth in vitro and used AtomNet® deep convolutional neural network software to identify potential small molecule inhibitors of PCK2-based structure. We iteratively tested candidate compounds in an in vitro PCK-2 enzyme assay. The impact of the top hit on metabolic flux and cell viability was also assessed. RESULTS: PCK2 downregulation decreased growth of BT-549 and MDA-MB-231 cells and reduced metabolic flux through pyruvate carboxylase. The first AtomNet® in silico structural screen of 7 million compounds yielded 86 structures that were tested in PCK2 enzyme assay in vitro. The top hit (IC50 = 2.4 µM) was used to refine a second round of in silico screen that yielded 82 candidates to be tested in vitro, which resulted in 45 molecules with inhibition > 20%. In the second in vitro screen we also included 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate, previously suggested to be PCK2 inhibitor based on structure, which emerged as the top hit. The specificity of this compound was tested in PCK1 and PCK2 enzymatic assays and showed IC50 of 500 nM and 3.5-27 nM for PCK1 and PCK2, respectively. CONCLUSION: 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate is a high affinity PCK2 enzyme inhibitor that also has significant growth inhibitory activity in breast cell lines in vitro and represents a potential therapeutic lead compound.

Management of triple-negative breast cancer by natural compounds through different mechanistic pathways.

Triple-negative breast cancer (TNBC) is the most severe form of breast cancer, characterized by the loss of estrogen, progesterone, and human epidermal growth factor receptors. It is caused by various genetic and epigenetic factors, resulting in poor prognosis. Epigenetic changes, such as DNA methylation and histone modification, are the leading mechanisms responsible for TNBC progression and metastasis. This review comprehensively covers the various subtypes of TNBC and their epigenetic causes. In addition, the genetic association of TNBC with all significant genes and signaling pathways linked to the progression of this form of cancer has been enlisted. Furthermore, the possible uses of natural compounds through different mechanistic pathways have also been discussed in detail for the successful management of TNBC.

Evaluating the Cellular Roles of the Lysine Acetyltransferase Tip60 in Cancer: A Multi-Action Molecular Target for Precision Oncology.

Precision (individualized) medicine relies on the molecular profiling of tumors' dysregulated characteristics (genomic, epigenetic, transcriptomic) to identify the reliance on key pathways (including genome stability and epigenetic gene regulation) for viability or growth, and then utilises targeted therapeutics to disrupt these survival-dependent pathways. Non-mutational epigenetic changes alter cells' transcriptional profile and are a key feature found in many tumors. In contrast to genetic mutations, epigenetic changes are reversable, and restoring a normal epigenetic profile can inhibit tumor growth and progression. Lysine acetyltransferases (KATs or HATs) protect genome stability and integrity, and Tip60 is an essential acetyltransferase due to its roles as an epigenetic and transcriptional regulator, and as master regulator of the DNA double-strand break response. Tip60 is commonly downregulated and mislocalized in many cancers, and the roles that mislocalized Tip60 plays in cancer are not well understood. Here we categorize and discuss Tip60-regulated genes, evaluate Tip60-interacting proteins based on cellular localization, and explore the therapeutic potential of Tip60-targeting compounds as epigenetic inhibitors. Understanding the multiple roles Tip60 plays in tumorigenesis will improve our understanding of tumor progression and will inform therapeutic options, including informing potential combinatorial regimes with current chemotherapeutics, leading to improvements in patient outcomes.

HTB50-2 Inhibits Growth and Migration of Triple-negative Breast Cancer via FOSL2/FOXC1 Signaling Axis and Subsequent Ferroptosis.

BACKGROUND: The manipulation of ferroptosis in cancer cells is a possible therapeutic technique that has been investigated for use in the treatment of cancer. Consequently, ferroptosis-inducing medications have recently received increased interest in cancer therapy. In this research, we assessed the anticancer efficacy of 14ß-hydroxy- 3ß-(ß-D-Glucopyranosyloxy)-5α-bufa-20,22-dienolide (HTB50-2), a natural product derived from the plant Helleborus thibetanus Franch, in Triple-Negative Breast Cancer (TNBC). Moreover, we also studied its potential mechanisms. METHODS: The biological effects of HTB50-2 in a series of breast cancer cell lines were analyzed using sulforhodamine B (SRB) and other methods. The migration ability was analyzed using three methods: wound healing assay, transwell assay, and Western blot. Meanwhile, the potential therapeutic value of HTB50-2 was evaluated in BALB/c mice by orthotopic transplantation. Transcriptome sequencing was conducted to explore the FOS-like antigen 2 (FOSL2) gene, and its role in ferroptosis was verified by Western blot and immunohistochemistry. The association of FOSL2 and ferroptosis-related genes was analyzed using NetworkAnalyst databases, and a TF-Gene interaction network was constructed. RESULTS: Ferroptosis was found to be induced in TNBC cells by HTB50-2. Furthermore, HTB50-2 inhibited tumor development by inducing ferroptosis in TNBC in vivo. Mechanistically, we demonstrated that a transcription factor FOSL2 mediated ferroptosis by HTB50-2. Additionally, it was found that Forkhead box C1 (FOXC1) was regulated by FOSL2 and correlated with ferroptosis. CONCLUSION: Our data suggest that HTB50-2 exerts its anti-cancer properties by ferroptosis via FOSL2/FOXC1 signaling pathway. Hence, HTB50-2 has an important application potential in the treatment of TNBC.

Trop2-targeted therapy in breast cancer.

Human trophoblastic cell surface antigen 2 (Trop2) is a glycoprotein, a cellular marker of trophoblastic and stem cells, and a calcium signaling transducer involved in several signaling pathways, leading to the proliferation, invasion, and metastasis of tumors. It is expressed at a low level in normal epithelial cells, but at a high level in many tumors, making it an ideal target for cancer therapy. According to previous literature, Trop2 is broadly expressed in all breast cancer subtypes, especially in triple negative breast cancer (TNBC). Several clinical trials have demonstrated the effectiveness of Trop2-targeted therapy in breast cancer. Sacituzumab govitecan (SG) is a Trop2-targeted antibody-drug conjugate (ADC) that has been approved for the treatment of metastatic TNBC and hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer. This article reviews the structure and function of Trop2, several major Trop2-targeted ADCs, other appealing novel Trop2-targeted agents and relevant clinical trials to provide a landscape of how Trop2-targeted treatments will develop in the future.