Pathogenesis of Triple-Negative Breast Cancer

Real-world perioperative treatment patterns and economic burden of recurrence in early-stage HER2-negative breast cancer: a SEER-Medicare study

AIM

This study aimed to describe treatment patterns and quantify the economic impact of recurrence in early-stage human epidermal growth factor receptor 2 (HER2)-negative breast cancer (BC).

MATERIALS & METHODS

Medicare beneficiaries with stages I-III HER2-negative BC and lumpectomy or partial/total mastectomy were identified from SEER-Medicare data (2010-2019). Perioperative therapies were reported in the neoadjuvant and adjuvant setting. Locoregional recurrence and distant metastasis were identified using a claims-based algorithm developed with clinical input and consisting of a diagnosis-based and treatment-based indicator. All-cause and BC-related healthcare resource utilization (HRU) per-patient-month and monthly healthcare costs were estimated from the recurrence date for patients with recurrence and from an imputed index date for patients without recurrence using frequency matching. HRU and costs were compared between groups stratified by hormone receptor-positive (HR+) or triple negative BC (TNBC) using multivariable regression models.

RESULTS

Of 28,655 patients, 8.5% experienced recurrence, 90.4% had HR+ disease, and 5.6% received neoadjuvant therapy. Relative to patients without recurrence, patients with recurrence had more advanced disease (stage II/III: 73.7% vs. 34.0%) and higher-grade tumors (Grade 3/4: 40.6% vs. 18.0%) at diagnosis. Recurrence in HR+/HER2-negative BC and TNBC was associated with higher rates of all-cause hospitalizations (incidence rate ratio [IRR]: 2.84 and 3.65), emergency department (ED) visits (IRR: 1.75 and 2.00), and outpatient visits (IRR: 1.46 and 1.55; all p < 0.001). Similarly, recurrence was associated with higher rates of BC-related HRU, particularly for ED visits in HR+/HER2-negative BC (IRR: 4.24; p < 0.001) and hospitalizations in TNBC (IRR: 11.71; p < 0.001). Patients with HR+/HER2-negative BC and TNBC recurrence incurred higher monthly all-cause (cost difference [CD]: $3988 and $4651) and BC-related healthcare costs (CD: $3743 and $5819).

CONCLUSIONS

Our findings highlight the considerable economic burden of recurrence in early-stage HER2-negative BC and underscore the unmet need for optimization of therapies that reduce recurrence in this population.

Protein lactylation within the nucleus independently predicts the prognosis of non‑specific triple‑negative breast cancer

Protein lactylation represents a pervasive post-translational modification prevalent in histones and diverse proteins, fostering tumor initiation and progression. Nonetheless, the impact of protein lactylation on the prognosis of non-specific triple-negative breast cancer (TNBC) remains uncertain. In the present study, the pan-lysine lactylation (panKlac) levels in cytoplasmic and nuclear compartments were semi-quantitatively examined using a tissue microarray encompassing 77 non-specific TNBC tissues. The association of the prognosis of patients with the panKlac levels in the cytoplasmic and nuclear compartments or other tumor attributes was assessed using Kaplan-Meier and Cox regression analyses. Furthermore, the molecular pathways involved in the promotional effect of lactylation on cell proliferation were determined through a transcriptomic analysis. The results indicated that the panKlac levels were markedly higher in tumor tissues than in para-tumor mammary regions and showed no significant correlations with various clinicopathological parameters, such as tumor dimension, lymph node involvement or histological grading. Notably, high panKlac levels within the nucleus served as an independent predictor of recurrence-free survival, whereas high cytoplasmic panKlac levels were a protective factor for patient survival. The panKlac levels were also markedly elevated in the TNBC cell line, MDA-MB-231. Additionally, glycolysis inhibition significantly reduced the global panKlac levels and concurrently diminished cell proliferation. According to the comprehensive transcriptomic analysis results, pathways related to ribosomal subunit biosynthesis/assembly and aminoacyl-tRNA biosynthesis were involved in the tumor-promoting mechanisms of lactylation. Further results revealed the oncogenic propensity of tyrosyl-tRNA synthetase 1 (YARS1) and its association with lactate production. Overall, Klac levels within the nucleus are an independent prognostic indicator for patients with non-specific TNBC. It is imperative to delve deeper into the roles and mechanisms of nuclear protein lactylation and YARS1 in non-specific TNBC.

Gadolinium ion-loaded mesoporous organosilica nanoplatform for enhanced radiotherapy in breast tumor treatment

Triple-negative breast cancer (TNBC) is a highly aggressive subtype with limited therapeutic options, often exhibiting resistance to standard radiotherapy (RT) and chemotherapy. Recent advancements in nanomedicine provide an opportunity to enhance treatment efficacy through innovative drug delivery systems and radiosensitizers. In this study, we present a novel nanotheranostic platform, MOs-G@DOX, engineered to enhance the therapeutic efficacy of RT in the treatment of TNBC. This platform consists of gadolinium-containing mesoporous organosilica nanoparticles (MOs-G) that serve a dual function as a drug carrier and a radiosensitizer. The MOs-G were synthesized via a surfactant-mediated sol-gel process, followed by gadolinium incorporation through nanoprecipitation. The antitumor drug doxorubicin (DOX) was subsequently loaded into the mesoporous structure, forming the MOs-G@DOX nanoplatform. Comprehensive in vitro and in vivo studies demonstrated that MOs-G@DOX exhibits excellent biocompatibility and significantly enhances the radiosensitivity of TNBC cells, leading to superior tumor growth inhibition compared to conventional treatments. The stability of MOs-G, with minimal gadolinium ion leakage, further underscores its potential as a safe and effective nanomedicine. Additionally, the combination of MOs-G@DOX with RT showed a marked increase in reactive oxygen species (ROS) generation and tumor cell apoptosis, which were confirmed through histological analyses. These findings suggest that MOs-G@DOX is a promising candidate for advancing cancer therapy, particularly in the context of RT for TNBC.

Core-shell vector-mediated co-delivery of CRISPR/Cas9 system and hydrophobic drugs against triple-negative breast cancer stem cells

Cancer stem cells (CSCs) play an important role in the development of triple-negative breast cancer (TNBC), including metastasis, invasion, tumorigenicity, and drug resistance. Moreover, non-CSCs can spontaneously transform into CSCs in special tumor microenvironments, thereby leading to poor prognosis or even failed treatments. Therefore, reversing CSCs into normal tumor cells in a sustained-acting manner is a promising strategy. It has been reported that down-regulation of FBXO44 protein expression inhibits tumor cell stemness. Moreover, CRISPR/Cas9 technology, a well-known precise gene editing tool, was adopted to permanently block FBXO44 within the genome upon its successful implementation. Given this, a core-shell nanoparticle (NP) consisting of amphiphilic polymer core and crosslinked-hyaluronic acid shell (nDOX-PL/pFBXO44 NPs) is developed in this work to concurrently deliver FBXO44-targeted CRISPR/Cas9 plasmids (pFBXO44) and doxorubicin (DOX) for combinational CSC reprogramming and chemotherapy of TNBC, which exhibits tumor cell targeting, endosomal escape, and reduction responsiveness to release DOX and plasmids in the cytoplasma. CRISPR/Cas9-mediated downregulation of FBXO44 expression could convert CSC into normal tumor cells, and effectively inhibit tumor growth without obvious side effects in vivo after combining with chemotherapy. In summary, we developed an intelligent system to co-deliver genetic and hydrophobic drugs, achieving effective cancer stemness reversal and synergistic suppression of contractable TNBC.

Canine mammary tumors as a promising adjunct preclinical model for human breast cancer research: similarities, opportunities, and challenges

Despite significant progress in the field of human breast cancer research and treatment, there is a consistent increase in the incidence rate of 0.5 percent annually, posing challenges in the development of effective novel therapeutic strategies. The failure rate of drugs in clinical trials stands at approximately 95%, primarily attributed to the limitations and lack of reliability of existing preclinical models, such as mice, which do not mimic human tumor biology. This article examines the potential utility of canine mammary tumors as an adjunct preclinical model for investigating human breast cancer. Given the numerous similarities between canine and human breast cancer, canines present a promising alternative model. The discussion delves into the intricate molecular and clinical aspects of human breast cancer and canine mammary tumors, shedding light on the tumors' molecular profiles, identifying specific molecular markers, and the application of radiological imaging modalities. Furthermore, the manuscript addresses the current constraints of preclinical cancer studies, the benefits of using canines as models, and the obstacles linked to the canine mammary tumors model. By concentrating on these elements, this review aims to highlight the viability of canine models in enhancing our understanding and management of human breast cancer.

FOSL1 transcriptionally dictates the Warburg effect and enhances chemoresistance in triple-negative breast cancer

BACKGROUND

Dysregulated energy metabolism has emerged as a defining hallmark of cancer, particularly evident in triple-negative breast cancer (TNBC). Distinct from other breast cancer subtypes, TNBC exhibits heightened glycolysis and aggressiveness. However, the transcriptional mechanisms of aerobic glycolysis in TNBC remains poorly understood.

METHODS

The Cancer Genome Atlas (TCGA) cohort was utilized to identify genes associated with glycolysis. The role of FOSL1 in glycolysis and tumor growth in TNBC cells was confirmed through both loss-of-function and gain-of-function experiments. The subcutaneous xenograft model was established to evaluate the therapeutic potential of targeting FOSL1 in TNBC. Additionally, chromatin immunoprecipitation and luciferase reporter assays were employed to investigate the transcriptional regulation of glycolytic genes mediated by FOSL1.

RESULTS

FOSL1 is identified as a pivotal glycolysis-related transcription factor in TNBC. Functional verification shows that FOSL1 enhances the glycolytic metabolism of TNBC cells, as evidenced by glucose uptake, lactate production, and extracellular acidification rates. Notably, FOSL1 promotes tumor growth in TNBC in a glycolysis-dependent manner, as inhibiting glycolysis with 2-Deoxy-D-glucose markedly diminishes the oncogenic effects of FOSL1 in TNBC. Mechanistically, FOSL1 transcriptionally activates the expression of genes such as SLC2A1, ENO1, and LDHA, which further accelerate the glycolytic flux. Moreover, FOSL1 is highly expressed in doxorubicin (DOX)-resistant TNBC cells and clinical samples from cases of progressive disease following neoadjuvant chemotherapy. Targeting FOSL1 proves effective in overcoming chemoresistance in DOX-resistant MDA-MB-231 cells.

CONCLUSION

In summary, FOSL1 establishes a robust link between aerobic glycolysis and carcinogenesis, positioning it as a promising therapeutic target, especially in the context of TNBC chemotherapy.

PD‑1/PD‑L1 inhibitor‑based immunotherapy in locally advanced or metastatic triple‑negative breast cancer: A meta‑analysis

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that is negative for oestrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 expression. Locally advanced and metastatic TNBC not only have a worse prognosis and are more invasive than TNBC, but are also the most immunogenic subtypes of breast cancer. There is still a lack of clarity regarding the optimal treatment of locally advanced or metastatic TNBC. The present study aimed to assess the efficacy and safety of programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitor-based immunotherapy [i.e., immune checkpoint inhibitors (ICIs)] alone or in combination with other therapies for the treatment of locally advanced or metastatic TNBC. The PubMed, Cochrane Library, Embase and MEDLINE databases were searched up to July 19, 2023 to identify studies that examined the efficacy and safety of ICIs for treating TNBC. The primary outcomes were progression-free survival (PFS) and overall survival (OS). The secondary outcomes were safety and adverse events. The data were analysed using Review Manager 5.4. A total of 8 studies (3,338 patients) were included in the present meta-analysis. Compared with other therapies, ICIs had a significantly different effect on OS [hazard ratio (HR)=0.83; 95% confidence interval (CI)=0.69-1.00; P<0.05; I2=59%] in patients with locally advanced or metastatic TNBC. In addition, ICIs significantly prolonged PFS compared with other therapies (intent-to-treat: HR=0.81; 95% CI=0.75-0.88; P<0.00001; I2=0%). Immunotherapy based on PD-1/PD-L1 inhibitors showed variable efficacy on OS and PFS in TNBC, while a significant improvement was observed for PD-L1(+). Future studies should focus on PD-L1 subgroup status, which may help optimize personalized treatment regimens for TNBC.

LncRNA MCM3AP-AS1 promotes chemoresistance in triple-negative breast cancer through the miR-524-5p/RBM39 axis

Triple-negative breast cancer (TNBC) is the most lethal subtype of BC, with unfavorable treatment outcomes. Evidence suggests the engagement of lncRNA MCM3AP-AS1 in BC development. This study investigated the action of MCM3AP-AS1 in chemoresistance of TNBC cells. Drug-resistant TNBC cell lines SUM159PTR and MDA-MB-231R were constructed by exposure to increasing concentrations of doxorubicin/docetaxel (DOX/DXL). MCM3AP-AS1 and miR-524-5p expression levels were determined by RT-qPCR. RNA binding motif 39 (RBM39) level was measured using Western blot. Cell viability and apoptosis were assessed by CCK-8 assay and flow cytometry. The targeted binding of miR-524-5p with MCM3AP-AS1 or RBM39 was predicted by ECORI database and validated by dual-luciferase assays. The gain-and-loss of function assays were conducted in cells to investigate the interactions among MCM3AP-AS1, miR-524-5p, and RBM39. TNBC xenograft mouse models were established through subcutaneous injection of MCM3AP-AS1-silencing MDA-MB-231R cells and intraperitoneally administrated with DOX/DXL to verify the role of MCM3AP-AS1 in vivo. MCM3AP-AS1 was upregulated in drug-resistant TNBC cells, and MCM3AP-AS1 silencing could sensitize drug-resistant TNBC cells to chemotherapeutic drugs by promoting apoptosis. MCM3AP-AS1 targeted miR-524-5p. After DOX/DXL treatment, miR-524-5p inhibition partially reversed the effect of MCM3AP-AS1 silencing on inhibiting chemoresistance and promoting apoptosis of drug-resistant TNBC cells. miR-524-5p targeted RBM39. Silencing MCM3AP-AS1 promoted apoptosis via the miR-524-5p/RBM39 axis, thereby enhancing chemosensitivity of drug-resistant TNBC cells. MCM3AP-AS1 knockdown upregulated miR-524-5p, downregulated RBM39, and restrained tumor development in vivo. MCM3AP-AS1 silencing potentiates apoptosis of drug-resistant TNBC cells by upregulating miR-524-5p and downregulating RBM39, thereby suppressing chemoresistance in TNBC.

FOS-Mediated PLCB1 Induces Radioresistance and Weakens the Antitumor Effects of CD8+ T Cells in Triple-Negative Breast Cancer

Radioresistance and immune evasion are interactive and crucial events leading to treatment failure and progression of human malignancies. This research studies the role of phospholipase C beta 1 (PLCB1) in these events in triple-negative breast cancer (TNBC) and the regulatory mechanism. PLCB1 was bioinformatically predicted as a dysregulated gene potentially linked to radioresistance in TNBC. Parental TNBC cell lines were exposed to fractionated radiation for 6 weeks. PLCB1 expression was decreased in the first 2 weeks but gradually increased from Week 3. PLCB1 knockdown increased the radiosensitivity of the cells, as manifested by a decreased half-inhibitory dose of irradiation, reduced cell proliferation, apoptosis resistance, mobility, and tumorigenesis in mice. The FOS transcription factor promoted PLCB1 transcription and activated the PI3K/AKT signaling. Knockdown of FOS similarly reduced radioresistance and T cells-mediated immune evasion. However, the radiosensitivity of TNBC cells and the antitumor effects of CD8+ T cells could be affected by a PI3K/AKT activator or by the PLCB1 upregulation. The PLCB1 or FOS knockdown also suppressed radioresistance and tumorigenesis of the TNBC cells in mice. In conclusion, FOS-mediated PLCB1 induces radioresistance and weakens the antitumor effects of CD8+ T cells in TNBC by activating the PI3K/AKT signaling pathway.

New Approach in the Interpretation of Complex Triple-negative Breast Cancer Immunohistochemistry Specimens Processed With VENTANA PD-L1 (SP142) Assay

Triple-negative breast cancer (TNBC) is challenging to treat because of its lack of specific molecular targets. The IMMUNOPEG study aimed to evaluate a novel structured method for interpreting TNBC immunohistochemistry specimens processed with VENTANA PD-L1 (SP142) assay. The study involved 10 pathologists who evaluated 50 different immunohistochemistry specimens of TNBC with programmed death ligand 1 (PD-L1) expression considered challenging and that were previously evaluated by the scientific committee, using the NAVIFY Digital Pathology platform. Initially, the overall percent agreement (OPA) was 74%, with a negative percent agreement (NPA) of 68.2% for samples classified as negative, and a positive percent agreement (PPA) of 94.5% for positive samples. After training on the method, the OPA improved significantly to 81.6%, with the NPA increasing to 80.5% and the PPA decreasing to 85.5%. The mean percentage of the tumor area occupied by PD-L1-stained immune cells decreased from 2.5% to 1.6% post-training, approaching to the scientific committee's consensus of 1.029%. The study found that the pathologists' confidence in their assessments increased significantly when using the structured method, which was found to be easy to use by 9 out of 10 pathologists. All pathologists agreed that the structured method was useful for assessing PD-L1 expression. The study suggests that this method has potential value in interpreting challenging cases of PD-L1 immunohistochemistry (IHC) in TNBC. Further refinement and a training protocol may be necessary to enhance the method's efficiency. The potential for generalizing this structured method to other IHC procedures and pathologies warrants additional research.

STK32C modulates doxorubicin resistance in triple-negative breast cancer cells via glycolysis regulation

Understanding the mechanisms underlying doxorubicin resistance in triple-negative breast cancer (TNBC) holds paramount clinical significance. In our study, we investigate the potential of STK32C, a little-explored kinase, to impact doxorubicin sensitivity in TNBC cells. Our findings reveal elevated STK32C expression in TNBC specimens, associated with unfavorable prognosis in doxorubicin-treated TNBC patients. Subsequent experiments highlighted that STK32C depletion significantly augmented the sensitivity of doxorubicin-resistant TNBC cells to doxorubicin. Mechanistically, we unveiled that the cytoplasmic subset of STK32C plays a pivotal role in mediating doxorubicin sensitivity, primarily through the regulation of glycolysis. Furthermore, the kinase activity of STK32C proved to be essential for its mediation of doxorubicin sensitivity, emphasizing its role as a kinase. Our study suggests that targeting STK32C may represent a novel therapeutic approach with the potential to improve doxorubicin's efficacy in TNBC treatment.

circUBR5 promotes ribosome biogenesis and induces docetaxel resistance in triple-negative breast cancer cell lines via the miR-340-5p/CMTM6/c-MYC axis

OBJECTIVE

Docetaxel (DTX) represents an effective chemotherapeutic agent for treating triple-negative breast cancer (TNBC), but the efficacy is strongly limited by drug resistance. c-MYC-mediated ribosome biogenesis is considered a feasible strategy to confront chemoresistance in BC. We elucidated the impact of CMTM6 on TNBC DTX chemoresistance by governing c-MYC-mediated ribosome biogenesis, and its upstream ceRNA regulatory pathways.

METHODS

DTX-resistant TNBC cells MDA-MB-231R and HCC1937R were generated by exposing sensitive cells MDA-MB-231 and HCC1937 to escalating doses of DTX. The expression patterns of CMTM6 and c-MYC were assessed by Western blot. The relationships between CMTM6 and miR-340-5p, circUBR5 and miR-340-5p were determined using bioinformatics analysis, luciferase assay, RIP, RNA in situ hybridization and biotin-labeled miR co-precipitation assay. Following ectopic expression and depletion experiments in DTX-resistant cells, cell chemoresistance, apoptosis, colony formation and nascent protein synthesis were evaluated.

RESULTS

CMTM6 expression was elevated in DTX-resistant TNBC cells. CMTM6 knockdown enhanced apoptosis of DTX-resistant TNBC cells and increased their sensitivity to DTX by blocking c-MYC-mediated ribosome biogenesis. Mechanistically, miR-340-5p targeted CMTM6 and negatively regulated the expression of CMTM6 in DTX-resistant TNBC cells. Moreover, circUBR5 attenuated the repression on CMTM6 expression as a ceRNA for miR-340-5p. circUBR5 knockdown inactivated c-MYC-mediated ribosome biogenesis, and therefore enhanced DTX efficacy by promoting miR-340-5p binding to CMTM6.

CONCLUSION

circUBR5 knockdown facilitated miR-340-5p-targeted CMTM6 via a ceRNA mechanism, thereby reducing c-MYC-mediated ribosome biogenesis and accelerating chemosensitization of DTX-resistant TNBC cells, which offered a theoretical guideline for clinical research on the feasibility of inhibiting ribosome biogenesis to reduce TNBC chemoresistance.

The prognostic marker KRT81 is involved in suppressing CD8 + T cells and predicts immunotherapy response for triple-negative breast cancer

Triple-negative breast Cancer (TNBC) is an aggressive subtype lacking estrogen, progesterone, and HER2 receptors. Known for limited targeted therapies, it poses challenges and requires personalized treatment strategies. Differential analysis revealed a significant decrease in keratin 81 (KRT81) expression in non-TNBC samples and an increase in TNBC samples, lower KRT81 expression correlated with better TNBC patient outcomes. It emerged as an independent predictive factor for TNBC, with associations found between its expression and clinically relevant features. We further developed a nomogram for survival probability assessment based on Cox regression results, demonstrating its accuracy through calibration curves. Gene annotation analysis indicated that KRT81 is involved in immune-related pathways and tumor cell adhesion. KRT81 is associated with immune cell infiltration of Follicular helper T cells (Tfh) and CD8 + T cells, suggesting its potential impact on the immunological microenvironment. The study delved into KRT81's predictive value for immunotherapy responses, high expression of KRT81 was associated with greater potential for immune evasion. Single-cell RNA sequencing analysis pinpointed KRT81 expression within a specific malignant subtype which was a risk factor for TNBC. Furthermore, KRT81 promoted TNBC cell proliferation, migration, invasion, and adhesion was confirmed by gene knockout or overexpression assay. Co-culture experiments further indicated KRT81's potential role in inhibiting CD8 + T cells, and correlation analysis implied KRT81 was highly correlated with immune checkpoint CD276, providing insights into its involvement in the immune microenvironment via CD276. In conclusion, this comprehensive study positions KRT81 as a promising prognostic marker for predicting tumor progression and immunotherapy responses in TNBC.

Synthesis of Zinc Oxide-Doped Carbon Dots for Treatment of Triple-Negative Breast Cancer

Introduction

The anti-cancer properties of zinc oxide-doped carbon dots (CDs/ZnO) in inhibiting triple-negative breast cancer (TNBC) progression merit more investigation.

Methods

With citric acid as the carbon source, urea applied as the nitrogen source, and zinc oxide (ZnO) used as a reactive dopant, CDs/ZnO were synthesized by microwave heating in the current study, followed by the characterization and biocompatibility assessments. Subsequently, the anti-cancer capabilities of CDs/ZnO against TNBC progression were evaluated by various biochemical and molecular techniques, including viability, proliferation, migration, invasion, adhesion, clonogenicity, cell cycle distribution, apoptosis, redox homeostasis, metabolome, and transcriptome assays of MDA-MB-231 cells. Additionally, the in vivo anti-cancer potentials of CDs/ZnO against TNBC progression were analyzed using TNBC xenograft mouse models.

Results

The biocompatibility of CDs/ZnO was supported by the non-significant changes in the pathological and physiological parameters in the CDs/ZnO treated mice, alongside a non-cytotoxic effect of CDs/ZnO on the proliferation of normal cells. Notably, the CDs/ZnO treatments effectively decreased the viability, proliferation, migration, invasion, adhesion, and clonogenicity of MDA-MB-231 cells. Furthermore, the CDs/ZnO treatments induced cell cycle arrest, apoptosis, redox imbalance, metabolome disturbances, and transcriptomic alterations of MDA-MB-231 cells by regulating the MAPK signaling pathway. Additionally, the CDs/ZnO treatments markedly suppressed the in vivo tumor growth in the TNBC xenograft mouse models.

Conclusion

In this study, we synthesized CDs/ZnO via microwave heating, using citric acid as the carbon source, urea as the nitrogen source, and ZnO as a reactive dopant. We confirmed the biosafety and potent anti-cancer efficacy of CDs/ZnO in inhibiting TNBC progression by disrupting malignant cell behaviors through modulation of the MAPK signaling pathway.

The splicing machinery is dysregulated and represents a therapeutic vulnerability in breast cancer

Breast cancer (BCa) is a highly prevalent pathological condition (̴30% in women) with limited and subtype-dependent prognosis and therapeutic options. Therefore, BCa management might benefit from the identification of novel molecular elements with clinical potential. Since splicing process is gaining a great relevance in cancer, this work analysed the expression of multiple Spliceosome Components (SCs = 17) and Splicing Factors (SFs = 26) and found a drastic dysregulation in BCa (n = 69) vs. control (negative biopsies; n = 50) samples. Among all the components analysed, we highlight the upregulation of ESRP1 and down-regulation of PRPF8 and NOVA1 in BCa vs. control samples. Indeed, ESRP1 was specially overexpressed in triple-negative BCa (TNBCa) and associated with worse prognosis (i.e., higher BCa grade and lower overall survival), suggesting an association of ESRP1 with BCa aggressiveness. On the other hand, PRPF8 expression was generally downregulated in BCa with no associations to clinical characteristics, while NOVA1 expression was lower in TNBCa patients and highly aggressive tumours. Consistently, NOVA1 overexpression in vitro reduced functional parameters of aggressiveness in ER-/PR- cell lines (MDA-MB-231 and BT-549) but not in ER+/PR+ cells (MCF7), suggesting a critical role of NOVA1 in subtype-specific BCa. Finally, the in vitro pharmacological inhibition of splicing machinery using pladienolide B decreased aggressiveness features in all the BCa cell lines, showing a subtype-independent inhibitory potential, but being relatively innocuous in normal-like breast cells. These results demonstrate the profound dysregulation of the splicing machinery in BCa and their potential as source of promising diagnosis/prognosis markers, as well as valuable therapeutic targets for BCa.

Concurrent Amplification of Ferroptosis and Immune System Activation Via Nanomedicine-Mediated Radiosensitization for Triple-Negative Breast Cancer Therapy

Radiation therapy (RT) is one of the core therapies for current cancer management. However, the emergence of radioresistance has become a major cause of radiotherapy failure and disease progression. Therefore, overcoming radioresistance to achieve highly effective treatment for refractory tumors is significant yet challenging. Here, pH-responsive DSPE-PEoz modified hollow Bi2Se3-RSL3/diABZi (DP-HBN/RA) nanomedicine is designed as a radiation sensitizer for efficient treatment of triple-negative breast cancer by simultaneously amplifying ferroptosis and immune system activation. DP-HBN/RA can efficiently concentrate X-ray radiation energy inside the tumor, thereby promoting precise ionizing radiation exposure in tumor cells to produce large amounts of reactive oxygen species (ROS), leading to lipid peroxidation-induced ferroptosis. Meanwhile, ferroptotic cell death is intensified through the inactivation of GPX4 by RSL3 released from DP-HBN/RA to acidic conditions in the tumor microenvironment. Additionally, DP-HBN/RA enhances RT efficacy to exacerbate unrepairable DNA damage and release DNA fragments that activate the cGAS-STING signal pathway, evoking a systematic immune response. Ingeniously, the released diABZi reinforces cGAS-STING activation to boost the immunology antitumor effect. This work links the induction of ferroptosis and the initiation of systematic immune response to achieve highly effective tumor suppression, which opens up new avenues for future treatments of refractory tumors.

Molecular structure of polysaccharide mediated autophagy markers KIF23 and PRC1 proteins and their regulatory role in triple negative cancer through the p53 signaling pathway

As a process of intracellular degradation and recycling of its own components, abnormal regulation of autophagy has been strongly associated with the development of multiple cancer types, including triple-negative breast cancer. The amino acid sequences of KIF23 and PRC1 proteins were analyzed by bioinformatics method, their three-dimensional structures were predicted, and their interactions with polysaccharides were studied by molecular docking technology. The localization and expression patterns of KIF23 and PRC1 in cells were studied by cell biology techniques. By constructing breast cancer cell lines that stably overexpress or knock down KIF23 and PRC1, we evaluated the effect of these proteins on autophagy activity. Finally, molecular biological methods such as Western blot and real-time quantitative PCR were used to detect the expression changes of proteins related to p53 signaling pathway and the levels of autophagy markers such as LC3 and p62, thereby revealing the regulatory effects of KIF23 and PRC1 on autophagy of triple-negative breast cancer cells through p53 signaling pathway. The study found that the KIF23 and PRC1 proteins have complex three-dimensional structures, and their interactions with polysaccharides may affect their function during cell division and autophagy. In triple-negative breast cancer cells, overexpression of KIF23 and PRC1 significantly enhanced autophagy activity, while knockdown of these proteins inhibited autophagy. Further experiments showed that KIF23 and PRC1 regulate the expression of autophagy related proteins by influencing the activity of p53 signaling pathway. Overexpression of KIF23 and PRC1 led to inhibition of the p53 signaling pathway, while knocking down these proteins activated the p53 signaling pathway, which was consistent with reduced autophagy activity.

Recent advances targeting chemokines for breast cancer

Breast cancer (BC) is a complex and heterogeneous disease, and its onset and progression involve the interplay of multiple molecular mechanisms. Chemokines and their receptors are key regulators of cell migration and immune responses and contribute significantly to the pathophysiology of BC. This article reviews the classification, functions, and mechanisms of chemokines and their receptors in the proliferation, migration, invasion, and angiogenesis of BC cells. This study explores the regulatory roles of chemokines and their receptors in the immune microenvironment of BC, particularly the ways they influence the infiltration, polarization, and antitumor immune responses of immune cells. Finally, this article summarizes the current treatment strategies for breast cancer that utilize chemokines and their receptors and provides insights into future research directions and trends in this field.

METTL3/IGF2BP1 promotes the development of triple-negative breast cancer by mediating m6A methylation modification of PRMT7

BACKGROUND

PRMT7 is upregulated in breast cancer and promotes tumor metastasis. Here we aimed to explore the function and mechanism of PRMT7 in triple-negative breast cancer (TNBC).

METHODS

The expression of PRMT7, METTL3 and IGF2BP1 was detected by immunohistochemistry (IHC), qRT-PCR and western blot. Cell viability and proliferation were measured using MTT and EdU assay. Flow cytometry and TUNEL assays were used to evaluate apoptosis. Invasion and migration were assessed by transwell and wound healing assays, respectively. Glucose consumption and lactate production were measured to assess glycolysis. In addition, the interaction between METTL3 and PRMT was verified by methylated RNA immunoprecipitation. The roles of METTL3 and PRMT in vivo were investigated through a xenograft model.

RESULTS

PRMT7 was upregulated in TNBC tissues and cells, and the knockdown of PRMT7 inhibited cell proliferation, invasion, migration and glycolysis, but induced apoptosis in TNBC cells. METTL3/IGF2BP1 enhanced PRMT7 expression by mediating the m6A methylation modification of PRMT7. Besides, METTL3 knockdown suppressed the progression of TNBC cells and regulated the WNT/β-catenin pathway via PRMT7. Moreover, silencing METTL3 restrained TNBC tumor growth in vivo through regulating PRMT7.

CONCLUSION

METTL3/IGF2BP1 facilitates the progression of TNBC by mediating m6A methylation modification of PRMT7.

Transcriptomic analysis reveals potential crosstalk genes and immune relationship between triple-negative breast cancer and depression

TNBC, the most aggressive form of breast cancer, lacks accurate and effective therapeutic targets. Immunotherapy presents a promising approach for addressing TNBC. Anxiety and depression are frequently concurrent symptoms in TNBC patients. MDD affects the tumor immune microenvironment of TNBC, with its characteristic genes affecting the pathophysiology of MDD and potentially increasing the risk of TNBC recurrence and metastasis. This study reveals significant differences in T lymphocyte infiltration between high-risk and low-risk TNBC groups based on MDD feature genes. This finding aids in identifying TNBC patients who may benefit from immunotherapy, providing new insights for future TNBC immunotherapy strategies. Our aim is to identify MDD-related genes involved in the pathogenesis of TNBC and to provide predictive biomarkers for TNBC immunotherapy.

Correlation Between Disease-Free Survival Endpoints and Overall Survival in Elderly Patients with Early-Stage HER2-Negative Breast Cancer: A SEER-Medicare Analysis

INTRODUCTION

Recent trial-level meta-analyses have established disease-free survival (DFS) as a valid surrogate for overall survival (OS) in human epidermal growth factor receptor 2-negative (HER2-) breast cancer (BC), irrespective of disease stage, and in early-stage hormone receptor-positive (HR+)/HER2- BC. To advance the understanding of the association between additional DFS endpoints and OS, this study assessed the patient-level correlations between DFS and OS, invasive DFS (IDFS) and OS, and distant DFS (DDFS) and OS in Medicare beneficiaries with early-stage HER2- BC, overall and in subgroups of patients with HR+/HER2- BC and triple-negative BC (TNBC).

METHODS

Patients with stages I-III HER2- BC aged ≥ 66 years were identified from SEER-Medicare data (2010-2019). DFS, IDFS, DDFS, and OS were assessed using Kaplan-Meier analyses. Normal scores rank correlation was estimated between each DFS endpoint and OS, overall and separately in patients with HR+/HER2- BC and TNBC.

RESULTS

Of 28,655 patients, 90.4% had HR+/HER2- BC and 9.6% had TNBC (median follow-up 4 years). Median DFS, IDFS, and DDFS were 4.5, 5.9, and 6.3 years, respectively, in HR+/HER2- BC and 3.0, 3.8, and 4.4 years, respectively, in TNBC. Median OS was not reached (5-year OS, HR+/HER2- BC 83.7%; TNBC 67.7%). A significant positive correlation was observed between each DFS endpoint and OS across cohorts, with the strongest correlation observed between DDFS and OS in HR+/HER2- BC (correlation coefficient 0.60; 95% confidence interval 0.57-0.62; p < 0.001) and in TNBC (0.69; 0.65-0.71; p < 0.001).

CONCLUSION

We observed significant positive patient-level correlations between DFS and OS, IDFS and OS, and DDFS and OS in early-stage HER2- BC. Our IDFS and DDFS findings advance the understanding of the role of these DFS endpoints as predictors of OS, and their potential utility as surrogate endpoints in clinical trials of early-stage HER2- BC, given additional validation in trial-level meta-analyses.

Expression and prognostic impact of hypoxia- and immune escape-related genes in triple-negative breast cancer: A comprehensive analysis

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that lacks effective therapeutic options. Hypoxia and immune escape are critical factors that contribute to the progression of and resistance to therapy in patients with TNBC. Nevertheless, few studies have comprehensively analyzed hypoxia and immune escape in patients with TNBC. This study aimed to examine the expression of hypoxia- and immune escape-related genes in TNBC and their influence on prognosis. TNBC datasets were downloaded and processed from The Cancer Genome Atlas and Gene Expression Omnibus. Differential expression analysis identified 4949 differentially expressed genes, between TNBC and normal tissues. The intersection yielded 116 hypoxia- and immune escape-related differentially expressed genes (H&IERDEGs), including KIF4A, BIRC5, and BUB1. Enrichment analyses indicated that H&IERDEGs were significantly enriched in biological processes, including cell chemotaxis, leukocyte migration, and cytokine-cytokine receptor interaction. Subsequently, weighted gene co-expression network analysis identified 43 module genes that were found to define two TNBC subtypes. We constructed a prognostic risk model consisting of eight signature genes, which demonstrated a high predictive performance to predict the overall survival (OS) of patients with TNBC with an area under the curve (AUC) exceeding 0.9 at 1 year survival. This indicates that the model effectively differentiates between outcomes, reflecting its robust performance. This study investigated the roles and potential mechanisms of hypoxia- and immune escape-related genes in TNBC and constructed a prognostic risk model with a high predictive performance. These findings offer novel molecular markers and potential therapeutic targets for TNBC.

Tumor Microenvironment-Responsive Nanoparticles Enhance IDO1 Blockade Immunotherapy by Remodeling Metabolic Immunosuppression

The clinical efficacy of immune checkpoint blockade (ICB) therapy is significantly compromised in the metabolically disordered tumor microenvironment (TME), posing a formidable challenge that cannot be ignored in current antitumor strategies. In this study, TME-responsive nanoparticles (HMP1G NPs) loaded with 1-methyltryptophan (1-MT; an indoleamine 2,3-dioxygenase 1 [IDO1] inhibitor,) and S-nitrosoglutathione (GSNO; a nitric oxide donor) is developed to enhance the therapeutic efficacy of 1-MT-mediated ICB. The HMP1G NPs responded to H+ and glutathione in the TME, releasing Mn2+, GSNO, and 1-MT. The released Mn2+ catalyzed the production of abundant reactive oxygen species and nitric oxide from hydrogen peroxide and GSNO, and the generated nitric oxide, synergistically with 1-MT, inhibited the accumulation of kynurenine mediated by IDO1 in the tumor. Mechanistically, HMP1G NPs downregulated tumor cell-derived IDO1 via the aryl hydrocarbon receptor/signal transducer and activator of transcription 3/interleukin signaling axis to improve kynurenine/tryptophan metabolism and immunosuppression. In a murine breast cancer model, treatment with HMP1G NPs elicited effective antitumor immunity and enhanced survival outcomes. This study highlights a novel nano-platform that simultaneously improves metabolism and enhances ICB efficacy to achieve a new and efficient antitumor strategy.

The Genomic and Biologic Landscapes of Breast Cancer and Racial Differences

Breast cancer is a significant health challenge worldwide and is the most frequently diagnosed cancer among women globally. This review provides a comprehensive overview of breast cancer biology, genomics, and microbial dysbiosis, focusing on its various subtypes and racial differences. Breast cancer is primarily classified into carcinomas and sarcomas, with carcinomas constituting most cases. Epidemiology and breast cancer risk factors are important for public health intervention. Staging and grading, based on the TNM and Nottingham grading systems, respectively, are crucial to determining the clinical outcome and treatment decisions. Histopathological subtypes include in situ and invasive carcinomas, such as invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC). The review explores molecular subtypes, including Luminal A, Luminal B, Basal-like (Triple Negative), and HER2-enriched, and delves into breast cancer's histological and molecular progression patterns. Recent research findings related to nuclear and mitochondrial genetic alterations, epigenetic reprogramming, and the role of microbiome dysbiosis in breast cancer and racial differences are also reported. The review also provides an update on breast cancer's current diagnostics and treatment modalities.

Discovery of a novel Fam20C inhibitor for treatment of triple-negative breast cancer

Sequence similarity 20 family member C (Fam20C), a Golgi casein kinase, has a gradually elucidated mechanism in triple-negative breast cancer (TNBC) and is considered a possible target for therapeutic intervention. In this study, we combined virtual screening and chemical synthesis methods to obtain a new small-molecule Fam20C inhibitor, compound 5k, which possesses desirable kinase inhibitory activity against Fam20C and significant anti-proliferative activity against MDA-MB-231 and BT-549 cells. Subsequently, cellular thermal shift assay (CETSA), molecular docking, and molecular dynamics (MD) simulations revealed that compound 5k binds to Fam20C. Moreover, compound 5k showed favorable antitumor efficacy in TNBC cells and xenograft models by promoting apoptosis and inhibiting migration. Mechanistically, compound 5k can inhibit the proliferation, promote apoptosis, and inhibit migration of TNBC cells by targeting Fam20C, thereby inhibiting the deterioration of TNBC and preventing its progression. Taken together, these results suggest that compound 5k can be utilized as a novel Fam20C inhibitor, laying a foundation for the discovery of more small-molecule drugs for the treatment of TNBC in the future.

Olaparib monotherapy in advanced triple-negative breast cancer patients with homologous recombination deficiency and without germline mutations in BRCA1/2: The NOBROLA phase 2 study

PURPOSE

To evaluate olaparib in advanced triple negative breast cancer (TNBC) patients with homologous recombination deficiency (HRD) and no germline BRCA1/2 mutations (gBRCA1/2mut).

METHODS

NOBROLA (NCT03367689) is a single-arm, open-label, multicenter, phase IIa trial, enrolling adult patients with advanced TNBC without gBRCA1/2mut and with HRD, who were treated with olaparib. The primary endpoint was clinical benefit rate (CBR) per RECIST v.1.1.

RESULTS

Six of 114 patients were eligible and received olaparib. Median follow up was 8.5 months. CBR and overall response rate (ORR) were 50 % (95 % CI, 11.8-88.2).

CONCLUSIONS

The observed results could prompt further investigation.

TRIAL

ClinicalTrials.gov identifier NCT03367689.

A gap analysis of UK biobank publications reveals SNPs associated with intrinsic subtypes of breast cancer

Breast cancer is a multifaceted disease and a leading cause of cancer morbidity and mortality in females across the globe. In 2020 alone, 2.3 million women were diagnosed and 685,000 died of breast cancer worldwide. With the number of diagnoses projected to increase to 3 million per year by 2040 it is essential that new methods of detection and disease stratification are sought to decrease this global cancer burden. Although significant improvements have been made in breast cancer diagnosis and treatment, the prognosis of breast cancer remains poor in some patient groups (i.e. triple negative breast cancer), necessitating research into better patient stratification, diagnosis and drug discovery. The UK Biobank, a comprehensive biomedical and epidemiological database with a wide variety of multiomics data (genomics, proteomics, metabolomics) offers huge potential to uncover groundbreaking discoveries in breast cancer research leading to improved patient stratification. Combining genomic, proteomic, and metabolic profiles of breast cancer in combination with histological classification, can aid treatment decisions through accurate diagnosis and prognosis prediction of tumor behaviour. Here, we systematically reviewed PubMed publications reporting the analysis of UK Biobank data in breast cancer research. Our analysis of UK Biobank studies in the past five years identified 125 publications, of which 76 focussed on genomic data analysis. Interestingly, only two studies reported the analysis of metabolomics and proteomics data, with none performing multiomics analysis of breast cancer. A meta-analysis of the 76 publications identified 2870 genetic variants associated with breast cancer across 445 genes. Subtype analysis revealed differential genetic alteration in 13 of the 445 genes and the identification of 59 well-established breast cancer genes. in differential pathways. Pathway interaction analyses illuminated their involvement in general cancer biomolecular pathways (e.g. DNA damage repair, Gene expression). While our meta-analysis only measured genetic differences in breast cancer due to current usage of UK Biobank data, minimal multi-omics analyses have been performed and the potential for harnessing multi-omics strategies within the UK Biobank cohort holds promise for unravelling the biological signatures of distinct breast cancer subtypes further in the future.

Triple-Negative Breast Cancer in Older Patients: Does SLNB Guide Therapy?

BACKGROUND

Older breast cancer patients represent a heterogeneous population. Studies demonstrate that sentinel lymph node biopsy (SLNB) omission may be appropriate in some clinical scenarios, yet patients with triple-negative breast cancer (TNBC) are often excluded from these studies. This study evaluated differences in treatment and survival for older patients with TNBC based on SLNB receipt and result.

METHODS

Patients 70 years old or older with a diagnosis of cT1-2/cN0/M0 TNBC (2010-2019) who underwent surgery were selected from the National Cancer Database. Logistic regression estimated the association of SLNB with therapy, and Cox proportional hazards models estimated the association of SLNB with overall survival (OS) after adjustment for select factors.

RESULTS

Of the 15,167 patients included in the study (median age, 77 years), 13.02% did not undergo SLNB, 5.14% had pN1 disease, 0.12% had pN2 disease, and 0.01% had pN3 disease. Most of the patients (83.9%) underwent surgery first, and 16.1% received neoadjuvant chemotherapy. Of those who underwent surgery first and SLNB, 6.2% had pN+ disease. Receipt of SLNB was associated with a higher likelihood of chemotherapy (odds ratio [OR] 1.85; 95% confidence interval [CI] 1.55-2.21), regardless of pN status. Compared with those who did not undergo a SLNB, a negative SLNB was significantly associated with lower mortality (hazard ratio [HR] 0.68; 95% CI 0.63-0.75), although there was no difference for a positive SLNB (HR 1.14; 95% CI 0.98-1.34). The patients receiving chemotherapy first showed no difference in survival based on SLNB receipt or result (p = 0.23).

CONCLUSIONS

Most older patients with TNBC do not have nodal involvement and do not receive chemotherapy. The receipt and results of SLNB may be associated with outcomes for some who undergo surgery first, but not for those who receive neoadjuvant chemotherapy.

Integrating mTOR Inhibition and Photodynamic Therapy Based on Carrier-Free Nanodrugs for Breast Cancer Immunotherapy

Conventional photodynamic therapy (PDT) in cancer treatment needs to utilize oxygen to produce reactive oxygen species to eliminate malignant tissues. However, oxygen consumption in tumor microenvironment exacerbates cancer cell hypoxia and may promote vasculature angiogenesis. Since the mammalian target of rapamycin (mTOR) signaling pathway plays a vital role in endothelial cell proliferation and fibrosis, mTOR inhibitor drugs hold the potential to reverse hypoxia-evoked angiogenesis for improved PDT effect. In this study, a carrier-free nanodrug formulation composed of Torin 1 as mTORC1/C2 dual inhibitor and Verteporfin as a photosensitizer and Yes-associated protein inhibitor is developed. These two drug molecules can self-assemble into stable nanoparticles through π-π stacking and hydrophobic interactions with good long-term stability. The nanodrugs can prompt synergistic apoptosis, combinational anti-angiogenesis, and strong immunogenic cell death effects upon near-infrared light irradiation in vitro. Furthermore, the nanosystem also exhibits improved antitumor effect, anti-cancer immune response, and distant tumor inhibition through tumor microenvironment remodeling in vivo. In this way, the nanodrugs can reverse PDT-elicited angiogenesis and promote cancer immunotherapy to eliminate tumor tissues and prevent metastasis. This nanosystem provides insights into integrating mTOR inhibitors and photosensitizers for safe and effective breast cancer treatment in clinical settings.

Harnessing the synergistic potential of NK1R antagonists and selective COX-2 inhibitors for simultaneous targeting of TNBC cells and cancer stem cells

Triple-negative breast cancer (TNBC) lacks the expression of oestrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), rendering it unresponsive to endocrine therapy and HER2 targeted treatments. Though certain chemotherapeutics targeting the cell cycle have shown efficacy to a certain extent, the presence of chemotherapy-resistant cancer stem cells (CSCs) presents a significant challenge in tackling TNBC. Multiple lines of evidence suggest the upregulation of neuropeptide Substance P (SP), its NK-1 receptor (NK1R) and the Cyclooxygenase-2 (COX-2) enzyme in TNBC patients. Upregulation of the SP/NK1R system and COX-2 influences major signalling pathways involved in cell proliferation, growth, survival, angiogenesis, inflammation, metastasis and stem cell activity. The simultaneous activation and crosstalk between the pathways activated by SP/NK1R and COX-2 consequently increase the levels of key regulators of self-renewal pathways in CSCs, promoting stemness. The combination therapy with NK1R antagonists and COX-2 inhibitors can simultaneously target TNBC cells and CSCs, thereby enhancing treatment efficacy and reducing the risk of recurrence and relapse. This review discusses the rationale for combining NK1R antagonists and COX-2 inhibitors for the better management of TNBC and a novel strategy to deliver drug cargo precisely to the tumour site to address the challenges associated with off-target binding.

PTGR1-mediated immune evasion mechanisms in late-stage triple-negative breast cancer: mechanisms of M2 macrophage infiltration and CD8+ T cell suppression

Triple-negative breast cancer (TNBC) is a heterogeneous disease characterized by metabolic dysregulation. Tumor cell immune escape plays an indispensable role in the development of TNBC tumors. Furthermore, in the abstract, we explicitly mention the techniques used and enhance the clarity and impact of our findings. "Based on bioinformatics analysis results, we utilized CRISPR/Cas9 technology to knockout the target gene and established a mouse model of breast cancer. Through experiments such as CCK8, scratch assay, and Transwell assay, we further investigated the impact of target gene knockout on the malignant behavior of tumor cells. Subsequently, we conducted immunohistochemistry and Western Blot experiments to study the expression of macrophage polarization and infiltration-related markers and evaluate the effect of the target gene on macrophage polarization. Next, through co-culture experiments, we simulated the tumor microenvironment and used immunohistochemistry staining to observe and analyze the distribution and activation status of M2 macrophages and CD8+ T cells in the co-culture system. We validated in vivo experiments the molecular mechanism by which the target gene regulates immune cell impact on TNBC progression.

Immunoglobulin-binding protein and Toll-like receptors in immune landscape of breast cancer

Breast cancer (BC) is a complex disease exhibiting significant heterogeneity and encompassing various molecular subtypes. Among these, triple-negative breast cancer (TNBC) stands out as one of the most challenging types, characterized by its aggressive nature and poor prognosis. This review embarks on a comprehensive exploration of the immune landscape of BC, with a primary focus on the functional and structural characterization of immunoglobulin-binding protein (BiP) and its pivotal role in regulating the unfolded response (UPR) pathway of proteins. Moreover, we unravel the multifaceted functions of BiP in BC, with a special emphasis on the involvement of cell surface BiP in TNBC metastasis, drug resistance, and its contribution to the formation of the tumor microenvironment (TME). We also provide mechanistic insights into how ER-resident BiP mediates the sensitization of drug-resistant BC to different treatment strategies, thereby offering promising avenues for therapeutic intervention. We also delve into the role of Toll-like receptors (TLRs), shedding light on their diverse expression patterns across BC and their influence on modulating the tumor immune response. Understanding the interplay between BiP, TLRs, and the immune response, especially in TNBC, opens avenues for novel immunotherapies. Future research should focus on developing targeted therapies that activate ER-resident BiP or inhibit cell surface BiP, and modulate TLR signaling. Moreover, exploring BiP as a biomarker for TNBC diagnosis, prognosis, and treatment response will be crucial for personalized medicine.

Identifying therapeutic strategies for triple-negative breast cancer via phosphoproteomics

INTRODUCTION

Given the poor prognosis of patients with TNBC, it is urgent to identify new biomarkers and therapeutic targets to enable personalized treatment strategies and improve patient survival. Comprehensive insights beyond genomic and transcriptomic analysis are crucial to improved outcomes for patients. As proteins are the workhorses of cellular function with their activity primarily regulated by phosphorylation, advanced phosphoproteomics techniques, such as mass spectrometry and antibody arrays, are essential for elucidating kinase signaling pathways that drive TNBC progression and contribute to therapy resistance.

AREA COVERED

This review discusses the critical need to integrate phosphoproteomics into TNBC research, evaluates commonly used technologies and their applications, and explores their advantages and limitations. We highlight significant findings from phosphoproteomic analyses in TNBC and address the challenges of implementing these technologies into clinical practice.

EXPERT OPINION

Rapid advances in phosphoproteomics analysis facilitate subtype stratification, adaptive response monitoring, and identification of biomarkers and therapeutic targets in TNBC. However, challenges in analyzing protein phosphorylation, especially in deep spatially resolved analysis of malignant cells and the tumor ecosystem, hinder the translation of phosphoproteomics to the CLIA setting. Nonetheless, phosphoproteomics offers a powerful tool that, when integrated into routine clinical practice, has the potential to revolutionize patient care.

Impact of HDAC6-mediated progesterone receptor expression on the response of breast cancer cells to hormonal therapy

Modulation of estrogen receptor (ER) and progesterone receptor (PR) expression, as well as their emerging functional crosstalk, remains a potential approach for enhancing the response to hormonal therapy in breast cancer. Aberrant epigenetic alterations induced by histone deacetylases (HDACs) were massively implicated in dysregulating the function of hormone receptors in breast cancer. Although much is known about the regulation of ER signaling by HDAC, the precise role of HDAC in modulating the expression of PR and its impact on the outcomes of hormonal therapy is poorly defined. Here, we demonstrate the involvement of HDAC6 in regulating PR expression in breast cancer cells. The correlation between HDAC6 and hormone receptors was investigated in patients' tissues by immunohistochemistry (n = 80) and publicly available data (n = 3260) from breast cancer patients. We explored the effect of modulating the expression of HDAC6 as well as its catalytic inhibition on the level of hormone receptors by a variety of molecular analyses, including Western blot, immunofluorescence, Real-time PCR, RNA-seq analysis and chromatin immunoprecipitation. Based on our in-silico and immunohistochemistry analyses, HDAC6 levels were negatively correlated with PR status in breast cancer tissues. The downregulation of HDAC6 enhanced the expression of PR-B in hormone receptor-positive and triple-negative breast cancer (TNBC) cells. The selective targeting of HDAC6 by tubacin resulted in the enrichment of the H3K9 acetylation mark at the PGR-B gene promoter region and enhanced the expression of PR-B. Additionally, transcriptomic analysis of tubacin-treated cells revealed enhanced activity of acetyltransferase and growth factor signaling pathways, along with the enrichment of transcription factors involved in the transcriptional activity of ER, underscoring the crucial role of HDAC6 in regulating hormone receptors. Notably, the addition of HDAC6 inhibitor potentiated the effects of anti-ER and anti-PR drugs mainly in TNBC cells. Together, these data highlight the role of HDAC6 in regulating PR expression and provide a promising therapeutic approach for boosting breast cancer sensitivity to hormonal therapy.

Developing an Arene Binuclear Ruthenium(II) Complex to Induce Ferroptosis and Activate the cGAS-STING Pathway: Targeted Inhibiting Growth and Metastasis of Triple Negative Breast Cancer

To effectively inhibit the growth and metastasis of triple-negative breast cancer (TNBC), we developed a high-efficiency and low-toxicity arene ruthenium (Ru) complex based on apoferritin (AFt). To achieve this, we optimized a series of Ru(II) 1,10-phenanthroline-2,9-diformaldehyde thiosemicarbazone complexes by studying their structure-activity relationships to obtain an arene binuclear Ru(II) complex (C5) with significant cytotoxicity and high accumulation in the mitochondria of tumor cells. Subsequently, a C5-AFt nanoparticle (NPs) delivery system was constructed. We found that the C5/C5-AFt NPs effectively inhibited TNBC growth and metastasis with few side effects. The C5-AFt NPs improved the anticancer and targeting abilities of C5 in vivo. Moreover, we confirmed the mechanism by which C5/C5-AFt NPs inhibit tumor growth and metastasis via mitochondrial damage-mediated ferroptosis and activation of the cGAS-STING pathway.

Transcriptional factor KLF9 overcomes 5-fluorouracil resistance in breast cancer via PTEN-dependent regulation of aerobic glycolysis

The emergence of resistance to 5-Fluorouracil (5-FU) is a staple in breast cancer chemotherapy. This paper delves into the role of PTEN in breast cancer resistance to 5-FU and examines the underlying molecular pathways. PTEN expression was detected in bioinformatics databases and upstream transcription factors (TFs) were identified. PTEN mRNA and protein levels, aerobic glycolysis proteins, lactate production, glucose consumption, and cell viability were measured. Binding interactions were confirmed, and cell proliferation assessed. In breast cancer cells, PTEN expression was downregulated. PTEN overexpression counteracted 5-FU resistance through the suppression of aerobic glycolysis. KLF9, as a TF upstream of PTEN, enhanced the levels of PTEN. In conclusion, the TF KLF9 inhibits the aerobic glycolysis level of breast cancer cells by up-regulating PTEN expression, thereby reducing their resistance to 5-FU. The discovery of this mechanism provides a new theoretical basis for the treatment of breast cancer.

Immunosuppressive SOX9-AS1 Resists Triple-Negative Breast Cancer Senescence Via Regulating Wnt Signalling Pathway

Long noncoding RNAs (lncRNAs) are involved in the regulation of triple-negative breast cancer (TNBC) senescence, while pro-carcinogenic lncRNAs resist senescence onset leading to the failure of therapy-induced senescence (TIS) strategy, urgently identifying the key senescence-related lncRNAs (SRlncRNAs). We mined seven SRlncRNAs (SOX9-AS1, LINC01152, AC005152.3, RP11-161 M6.2, RP5-968 J1.1, RP11-351 J23.1 and RP11-666A20.3) by bioinformatics, of which SOX9-AS1 was reported to be pro-carcinogenic. In vitro experiments revealed the highest expression of SOX9-AS1 in MDA-MD-231 cells. SOX9-AS1 knockdown inhibited cell growth (proliferation, cycle and apoptosis) and malignant phenotypes (migration and invasion), while SOX9-AS1 overexpression rescued these effects. Additionally, SOX9-AS1 knockdown facilitated tamoxifen-induced cellular senescence and the transcription of senescence-associated secretory phenotype (SASP) factors (IL-1α, IL-1β, IL-6 and IL-8) mechanistically by resisting senescence-induced Wnt signal (GSK-3β/β-catenin) activation. Immune infiltration analysis revealed that low SOX9-AS1 expression was accompanied by a high infiltration of naïve B cells, CD8+ T cells and γδ T cells. In conclusion, SOX9-AS1 resists TNBC senescence via regulating the Wnt signalling pathway and inhibits immune infiltration. Targeted inhibition of SOX9-AS1 enhances SASP and thus mobilises immune infiltration to adjunct TIS strategy.

Differential Abundance of DNA Damage Sensors and Innate Immune Signaling Proteins in Inositol Polyphosphate 4-Phosphatase Type II-Negative Triple-Negative Breast Cancer Classified by Immunotype

The influence of neoplastic cells on the tumor microenvironment is poorly understood. In this study, eight patient samples representing two immunotypes of triple-negative breast cancer (TNBC), defined by quantitative histologic criteria as T-cell desert and T-cell infiltrated (TCI), were compared via label-free quantitative protein mass spectrometry of material extracted directly from targeted regions of formalin-fixed, paraffin-embedded tissue sections. Of 2934 proteins quantitated, 439 were significantly differentially abundant, among which 361 were overabundant in TCI-TNBC. The 361-protein group included proteins involved in major histocompatibility complex-I antigen processing and presentation, viral defense, DNA damage response, and innate immune signaling. Immunohistochemical validation of selected proteins showed good positive correlation between neoplastic cell histoscores and label-free quantitation. Extension of immunohistochemical analysis to a total of 58 inositol polyphosphate 4-phosphatase type II-negative TNBC confirmed elevated levels of the DNA damage sensor interferon-γ-inducible protein 16, inflammasome adaptor apoptosis-associated speck-like protein containing a CARD (ASC), and pore-forming protein gasdermin D in TCI-TNBC neoplastic cells. By contrast, cGMP-AMP synthase inhibitor barrier to autointegration factor (BAF) was elevated in the neoplastic cells of T-cell desert TNBC. These findings demonstrate a previously unknown correlation between the degree of T-cell infiltration in inositol polyphosphate 4-phosphatase type II-negative TNBC and the levels, in cognate neoplastic cells, of proteins that modulate innate immune signaling in response to DNA damage.

Evolving therapeutics and ensuing cardiotoxicities in triple-negative breast cancer

Defined as scarce expression of hormone receptors and human epidermal growth factor receptor 2, triple-negative breast cancer (TNBC) is labeled as the most heterogeneous subtype of breast cancer with poorest prognosis. Despite rapid advancements in precise subtyping and tailored therapeutics, the ensuing cancer therapy-related cardiovascular toxicity (CTR-CVT) could exert detrimental impacts to TNBC survivors. Nowadays, this interdisciplinary issue is incrementally concerned by cardiologists, oncologists and other pertinent experts, propelling cardio-oncology as a booming field focusing on the whole-course management of cancer patients with potential cardiovascular threats. Here in this review, we initially profile the evolving molecular subtyping and therapeutic landscape of TNBC. Further, we introduce various monitoring approaches of CTR-CVT. In the main body, we elaborate on typical cardiotoxicities ensuing anti-TNBC treatments in detail, ranging from chemotherapy (especially anthracyclines), surgery, anesthetics, radiotherapy to immunotherapy, with future perspectives on promising directions in the era of artificial intelligence and traditional Chinese medicine.

Evolving immunotherapeutic solutions for triple-negative breast carcinoma

Triple-negative breast carcinoma (TNBC) remains a formidable clinical hurdle owing to its high aggressiveness and scant therapeutic options. Nonetheless, the evolving landscape of immunotherapeutic strategies opens up promising avenues for tackling this hurdle. This review discusses the advancing immunotherapy for TNBC, accentuating personalized interventions due to tumor microenvironment (TME) diversity. Immune checkpoint inhibitors (ICIs) hold pivotal significance, both as single-agent therapies and when administered alongside cytotoxic agents. Moreover, the concurrent inhibition of multiple immune checkpoints represents a potent approach to augment the efficacy of cancer immunotherapy. Synergistic effects have been observed when ICIs are combined with targeted treatments like PARP inhibitors, anti-angiogenics, and ADCs (antibody-drug conjugates). Emerging tactics include tumor vaccines, cellular immunotherapy, and oncolytic viruses, leveraging the immune system's ability for selective malignant cell destruction. This review offers an in-depth examination of the diverse landscape of immunotherapy development for TNBC, furnishing meticulous insights into various advancements within this field. In addition, immunotherapeutic interventions offer hope for TNBC, needing further research for optimization.

Repurposing propofol for breast cancer therapy through promoting apoptosis and arresting cell cycle

Breast cancer is the most prevalent cancer among women worldwide, characterized by a high mortality rate and propensity for metastasis. Although surgery is the standard treatment for breast cancer, there is still no effective method to inhibit tumor metastasis and improve the prognosis of patients with breast cancer after surgery. Propofol, one of the most widely used intravenous anesthetics in surgery, has exhibited a positive association with improved survival outcomes in patients with breast cancer post‑surgery. However, the underlying molecular mechanism remains to be elucidated. The present study revealed that triple negative breast cancer cells, MDA‑MB‑231 and 4T1, exposed to propofol exhibited a significant decrease in cell viability. Notably, propofol exhibited minimal cytotoxic effects on HUVECs under the same conditions. Furthermore, propofol significantly inhibited the migration and invasion ability of MDA‑MB‑231 and 4T1 cells. Propofol promoted apoptosis in 4T1 cells through upregulation of Bax and cleaved caspase 3, while downregulating B‑cell lymphoma‑extra large. Concomitantly, propofol induced cell cycle arrest of 4T1 cells by downregulating cyclin E2 and phosphorylated cell division cycle 6. Furthermore, propofol exhibited excellent anticancer efficacy in a 4T1 breast cancer allograft mouse model. The present study sheds light on the potential of propofol as an old medicine with a novel use for breast cancer treatment.

Phase separation of phospho-HDAC6 drives aberrant chromatin architecture in triple-negative breast cancer

How dysregulated liquid-liquid phase separation (LLPS) contributes to the oncogenesis of female triple-negative breast cancer (TNBC) remains unknown. Here we demonstrate that phosphorylated histone deacetylase 6 (phospho-HDAC6) forms LLPS condensates in the nuclei of TNBC cells that are essential for establishing aberrant chromatin architecture. The disordered N-terminal domain and phosphorylated residue of HDAC6 facilitate effective LLPS, whereas nuclear export regions exert a negative dominant effect. Through phase-separation-based screening, we identified Nexturastat A as a specific disruptor of phospho-HDAC6 condensates, which effectively suppresses tumor growth. Mechanistically, importin-β interacts with phospho-HDAC6, promoting its translocation to the nucleus, where 14-3-3θ mediates the condensate formation. Disruption of phospho-HDAC6 LLPS re-established chromatin compartments and topologically associating domain boundaries, leading to disturbed chromatin loops. The phospho-HDAC6-induced aberrant chromatin architecture affects chromatin accessibility, histone acetylation, RNA polymerase II elongation and transcriptional profiles in TNBC. This study demonstrates phospho-HDAC6 LLPS as an emerging mechanism underlying the dysregulation of chromatin architecture in TNBC.

Non-coding RNAs and estrogen receptor signaling in breast cancer: Nanotechnology-based therapeutic approaches

This review investigates the regulatory role of non-coding RNAs (ncRNAs) in estrogen receptor (ER) signaling pathways, particularly in the context of breast cancer therapy, with an emphasis on the emerging potential of nanotechnology for drug delivery. The information was obtained from reputable databases, including PubMed, Elsevier, Springer, Wiley, Taylor, and Francis, which contain past and present research. Breast cancer remains the most prevalent cancer among women worldwide, and ER signaling mechanisms heavily influence its progression. Treatment options have traditionally encompassed surgery, chemotherapy, radiation therapy, targeted therapy, and hormone therapy. In recent decades, nanomedicine has emerged as a promising approach to breast cancer treatment. By passively targeting tumor cells and reducing toxicity, nanodrugs can overcome the challenges of conventional chemotherapy. Additionally, nanocarriers can stimulate tumor cells, enhancing treatment efficacy. Recent advancements in nanomedicine offer promising approaches for targeted cancer therapy, potentially overcoming the limitations of conventional treatments. This review explores the interactions between long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) with ER pathways, their impact on breast cancer progression, and how these interactions can be leveraged to enhance therapeutic efficacy through nanotechnology-based drug delivery systems.

The lncRNA AFAP1-AS1 is upregulated in metastatic triple-negative breast tumors and controls hypoxia-activated vasculogenic mimicry and angiogenesis

BACKGROUND

Vasculogenic mimicry (VM) is an alternative intratumoral microcirculation system that depends on the capacity of tumor cells to reorganize and grow in three-dimensional (3D) channel architectures like the capillaries formed by endothelial cells. Both VM and angiogenesis may coordinately function to feed cancer cells, allowing tumor growth. Long noncoding RNAs (lncRNAs) regulate critical cellular functions in cancer cells, including cell proliferation, apoptosis, angiogenesis, invasion, and metastasis. The lncRNA, known as actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1), has been described as an oncogene in diverse types of cancers. However, its role in VM and metastasis in triple-negative breast cancer (TNBC) is unknown.

METHODS

Reverse transcription and quantitative polymerase chain reaction (RT‒qPCR) experiments were performed to evaluate the expression of 10 selected lncRNAs from literature in metastatic and nonmetastatic biopsies from TNBC patients. The expression of AFAP1-AS1 was analyzed in Genotype-Tissue Expression Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) datasets. The AFAP1-AS1 expression was knocked in TNBC Hs578T cells by transfection of specific siRNAs. Channel-like formation assays were performed using 3D cultures over Matrigel in hypoxia-treated Hs578T cancer cells with diminished expression of AFAP1-AS1. The angiogenesis tests were conducted using human umbilical vein endothelial cells (HUVECs) and AFAP1-AS1- silenced Hs578T cells on 3D cell cultures. The presence of VM (CD31-/PAS+) in tumor tissues from TNBC patients with and without metastasis was assessed through immunohistochemistry using endothelial marker CD31 antibodies and periodic acid-Schiff (PAS) staining.

RESULTS

Compared with normal mammary tissues, AFAP1-AS1 expression was higher in breast cancer tissues. Moreover, AFAP1-AS1 expression was upregulated in the TNBC subtype compared to receptor-positive breast tumors. In addition, the expression of AFAP1-AS1 was correlated with the expression of the thirteen genes characteristic of a previously reported hypoxia signature. Interestingly, AFAP1-AS1 was upregulated in primary TNBC tumors from patients who developed metastasis compared with the nonmetastatic group. Functional analysis revealed that the knockdown of AFAP1-AS1 in Hs578T cells significantly impaired the hypoxia-induced VM, accompanied by a decrease in the development of 3D channel networks. Similarly, AFAP1-AS1 knockdown counteracts the angiogenic potential of cancer cells, as indicated by a reduction in the number of polygons, sprouting cells, and nodes in HUVEC cells. Remarkably, an increase in CD31-/PAS + staining of 3D channel networks in primary breast tumors from metastatic patients was found compared with the nonmetastatic group. Finally, we found that the number of blood vessels increased in the nonmetastatic group more than in the metastatic cohort.

CONCLUSIONS

Our data suggested that AFAP1-AS1 controls both VM and angiogenesis in Hs578T breast cancer cells and that increased metastasis is associated with VM in TNBC patients.

Sacituzumab Govitecan in Triple Negative Breast Cancer: A Systematic Review of Clinical Trials

BACKGROUND/OBJECTIVES

Triple-negative breast cancer is difficult to treat due to the absence of hormone receptors and Her2neu. Sacituzumab govitecan is a new therapeutic approach that uses an antibody directed against the Trop-2 antigen present in solid epithelial tumors, linked to the active metabolite SN-38, similar to irinotecan, to specifically target cancer cells while minimizing damage to healthy cells. The objective of the present review was to evaluate the efficacy and safety of sacituzumab govitecan as a single treatment in patients with triple-negative breast cancer and to compare its results with the standard conventional chemotherapy regimen currently used in this disease.

METHODS

A systematic review of randomized clinical trials of sacituzumab govitecan was performed. The search was performed in Medline (PubMed), Web of Science, and Cochrane from September 2022 to January 2024.

RESULTS

Thirty-eight articles are included and evaluated according to inclusion and exclusion criteria corresponding to the two most relevant clinical trials, including specific analyses of cohorts and subgroup study arms within these trials. Data from more recent clinical trials are also reviewed.

CONCLUSIONS

The efficacy results showed a significantly greater clinical benefit with sacituzumab govitecan compared to standard chemotherapy in patients with triple-negative breast cancer. This drug will become a treatment of substantial impact in future treatment guidelines for this type of cancer.

tRNA-derived fragments: Unveiling new roles and molecular mechanisms in cancer progression

tRNA-derived fragments (tRFs) are novel small noncoding RNAs (sncRNAs) that range from approximately 14 to 50 nt. They are generated by the cleavage of mature tRNAs or precursor tRNAs (pre-tRNAs) at specific sites. Based on their origin and length, tRFs can be classified into three categories: (1) tRF-1 s; (2) tRF-3 s, tRF-5 s, and internal tRFs (i-tRFs); and (3) tRNA halves. They play important roles in stress response, signal transduction, and gene expression processes. Recent studies have identified differential expression of tRFs in various tumors. Aberrantly expressed tRFs have critical clinical value and show promise as new biomarkers for tumor diagnosis and prognosis and as therapeutic targets. tRFs regulate the malignant progression of tumors via various mechanisms, primarily including modulation of noncoding RNA biogenesis, global chromatin organization, gene expression regulation, modulation of protein translation, regulation of epigenetic modification, and alternative splicing regulation. In conclusion, tRF-mediated regulatory pathways could present new avenues for tumor treatment, and tRFs could serve as promising therapeutic targets for cancer therapy.

Uncovering novel pathogenic variants and pathway mutations in triple-negative breast cancer among the endogamous mizo tribe

PURPOSE

The incidence of triple-negative breast cancer (TNBC) in India is higher compared to Western populations. The objective of this study is to identify novel and less reported variants in TNBC in Mizoram, a state with a high cancer incidence in India.

METHODS

We analysed whole exome sequencing data from triple-negative breast cancer (TNBC) patients in the Mizo population to identify key and novel variants. Moreover, we analysed reported breast cancer-related genes and pathway alterations.

RESULTS

Somatic mutation analysis revealed that TP53 was the most frequently mutated gene and TP53, CACNA1E, IGSF3, RYR1, and FAM155A as significantly mutated driver genes. Based on the ACMG guidelines, we identified a rare pathogenic germline variant of BRCA1 (p.C1697R) in 13% and a likely pathogenic frameshift insertion in RBMX (p.P106Ffs) in 73% of the patients. We also found that the ATM, STK11, and CDKN2A genes were significantly mutated in germline TNBC samples compared to healthy samples. Moreover, we identified novel somatic variants in CHEK2 (p.K182M) and NF1 (p.C245X), and novel germline variants RB1 (p.D111G), CDH1 (p.A10Gfs), CDKN2A (p.V96G), CDKN2A (p.S12Afs*22), MAP3K1 (CAAdelins0), MSH6 (p.L1226_L1230del), and PMS2 (TTCdelins0). Pathway analysis revealed that most somatic mutations were highly associated with PI3K-Akt signalling pathway and MAPK signalling pathways in TNBC.

CONCLUSIONS

These findings identified novel variants and key genes contributing to disease development and progression. Further analysis of less studied genes, including RBMX, MRC1, ATM, CTNNB1, and CDKN2A, in TNBC may reveal new potential genes for targeted therapeutic strategies and contribute to clinical advancements in the treatment of TNBC.

Marine Staurosporine Analogues: Activity and Target Identification in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with high mortality and drug resistance and no targeted drug available at present. Compound 4, a staurosporine alkaloid derived from Streptomyces sp. NBU3142 in a marine sponge, exhibits potent anti-TNBC activity. This research investigated its impact on MDA-MB-231 cells and their drug-resistant variants. The findings highlighted that compound 4 inhibits breast cancer cell migration, induces apoptosis, arrests the cell cycle, and promotes cellular senescence in both regular and paclitaxel-resistant MDA-MB-231 cells. Additionally, this study identified mitogen-activated protein kinase kinase kinase 11 (MAP3K11) as a target of compound 4, implicating its role in breast tumorigenesis by affecting cell proliferation, migration, and cell cycle progression.

Improving efficacy of TNBC immunotherapy: based on analysis and subtyping of immune microenvironment

Triple-negative breast cancer (TNBC) is a highly aggressive type of breast cancer that encompasses several distinct subtypes. Recent advances in immunotherapy offer a promising future for the treatment of these highly heterogeneous and readily metastatic tumors. Despite advancements, the efficacy of immunotherapy remains limited as shown by unimproved efficacy of PD-L1 biomarker and limited patient benefit. To enhance the effectiveness of TNBC immunotherapy, we conducted investigation on the microenvironment, and corresponding therapeutic interventions of TNBC and recommended further investigation into the identification of additional biomarkers that can facilitate the subtyping of TNBC for more targeted therapeutic approaches. TNBC is a highly aggressive subtype with dismal long-term survival due to the lack of opportunities for traditional endocrine and targeted therapies. Recent advances in immunotherapy have shown promise, but response rates can be limited due to the heterogeneous tumor microenvironments and developed therapy resistance, especially in metastatic cases. In this review, we will investigate the tumor microenvironment of TNBC and corresponding therapeutic interventions. We will summarize current subtyping strategies and available biomarkers for TNBC immunotherapy, with a particular emphasis on the need for further research to identify additional prognostic markers and refine tailored therapies for specific TNBC subtypes. These efforts aim to improve treatment sensitivity and ultimately enhance survival outcomes for advanced-stage TNBC patients.

Electroporation enhances cell death in 3D scaffold-based MDA-MB-231 cells treated with metformin

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer lacks estrogen, progesterone, and HER2 receptors and hence, is therapeutically challenging. Towards this, we studied an alternate therapy by repurposing metformin (FDA-approved type-2 diabetic drug with anticancer properties) in a 3D-scaffold culture, with electrical pulses. 3D cell culture was used to simulate the tumor microenvironment more closely and MDA-MB-231, human TNBC cells, treated with both 5 mM metformin (Met) and 8 electrical pulses at 2500 V/cm, 10 µs (EP1) and 800 V/cm, 100 µs (EP2) at 1 Hz were studied in 3D and 2D. They were characterized using cell viability, reactive oxygen species (ROS), glucose uptake, and lactate production assays at 24 h. Cell viability, as low as 20 % was obtained with EP1 + 5 mM Met. They exhibited 1.65-fold lower cell viability than 2D with EP1 + 5 mM Met. ROS levels indicated a 2-fold increase in oxidative stress for EP1 + 5 mM Met, while the glucose uptake was limited to only 9 %. No significant change in the lactate production indicated glycolytic arrest and a non-conducive environment for MDA-MB-231 growth. Our results indicate that 3D cell culture, with a more realistic tumor environment that enhances cell death using metformin and electrical pulses could be a promising approach for TNBC therapeutic intervention studies.