Functions In Triple Negative Breast Cancer Research Articles

Tetrastigma hemsleyanum polysaccharide combined with doxorubicin promote ferroptosis and immune function in triple-negative breast cancer

The absence of effective therapeutic targets poses considerable obstacles to the treatment of triple-negative breast cancer (TNBC). This study aimed to explore the function and mechanism of polysaccharides derived from the aerial parts of Tetrastigma hemsleyanum (THP) for the treatment of TNBC. THP exerts notable anti-TNBC effects when used alone, and its combination with Doxorubicin (DOX) effectively augments the sensitivity of TNBC cells to DOX. Through RNA sequencing, Fe2+ assays, western blotting, and transmission electron microscopy, THP was identified as a natural inducer of ferroptosis and ferritinophagy through the xCT/GSH/GPX4 and Nrf2/NCOA4/FTH1 pathways. Further research revealed that the THP branched-chain hexose directly binds to the xCT protein to inhibit its expression and promotes ferroptosis. In vivo experiments confirmed the role of THP in inducing ferroptosis and showed that THP improves the tumor microenvironment and immune function by increasing the ratio of CD4+ and CD8+ T cells to regulatory T cells and modulating cytokine levels. As demonstrated by electrocardiography, blood chemistry, and histological analyses, THP alleviates organ toxicity caused by DOX. Overall, these results suggest that THP has significant clinical potential as a natural macromolecular drug and may provide a safe and effective treatment strategy for TNBC when combined with DOX.

Abstract PO2-15-10: Identifying new immune-related biomarkers in TNBC with a look at PD-L1 cell-autonomous role

Abstract Background The programmed death ligand 1 (PD-L1) has recently emerged as a target immunotherapy in Triple-negative breast cancer (TNBC). However, the tumor-intrinsic role of PD-L1 and its pathway still needs to be fully clarified. Recently, a close association between CD73, PD-L1, cancer cell steaminess and epithelial-to-mesenchymal transition phenotypes is emerging. In addition, we have previously demonstrated that miR-320a and miR-145 target PD-L1, whereas miR-30 family is known to target CD73. In this study, we aimed at investigating the role of these miRNAs as prognostic and predictive dynamic biomarkers for immunotherapy in TNBC. Additionally, we investigated whether PD-L1 exerts cellular autonomic functions in TNBC beyond its role in the immune checkpoint. Results CD73 and PD-L1 expression was assessed in a panel of breast cancer lines and the non-malignant breast cells MCF-10. We showed a significantly higher CD73 and PD-L1 expression in MDA-MB-231 (TNBC, Basal B) than in MCF-10. Conversely, in MCF-7 cells (HR +, Luminal A), CD73 and PD-L1 expression is lower than in MCF-10. Furthermore, we showed that low PDL1 expression is correlated with high levels of miR-320a and miR-145, and CD73 expression is inversely related to miR-30 expression. These putative biomarkers were also validated in two patients with different PD-L1 status. From the analysis of the data obtained by real-time qRT-PCR, we found high plasma level of CD73 and low plasma level of miR-320a, miR-145 and miR-30 in the patient with PD-L1 positive BC. On contrary, in the patient with PD-L1-negative BC, we found low plasma level of CD73 and high plasma level of miR-320a, miR-145 and miR-30. Furthermore, to explore whether PD-L1 could also have an intrinsic role in tumor development and invasiveness, we used stably MDA–MB-231 PD-L1-silenced cells. We found that cell growth, colony formation, migration rate and the ability to form spheres are consistently reduced upon shRNA-mediated PDL1 silencing. In particular, we observed a reduction in the number, diameter and volume of the 3D spheres compared to the control cells. To further demonstrate the role of PD-L1, we treated the PDL1-high expression cells MDA-MB-231, PD-L1 silenced MDA-MB-231 clones, and PD-L1 low expression cells MCF-7 with Durvalumab, an anti-PD-L1. Interestingly, we observed that in PD-L1 silenced clones and MCF-7 cells, the sphere-forming ability was increased in presence of Durvalumab treatment. On the contrary, in MDA-MB-231, Durvalumab inhibited the sphere-forming ability. Conclusion Our data confirm that PD-L1 and CD73 are targets of miR-320a/miR-145 and miR-30 respectively. These could be potential predictive dynamic biomarkers for chemotherapy, ICIs and anti-CD73 therapeutic approach. Future validations of these biomarkers in an extensive series of TNBC patients are needed to support their use in clinical practice. Here, we further characterized the cellular autonomic role of PD-L1 in breast cancer and showed a differential role of basal PD-L1 expression in PD-L1 checkpoint inhibitors treatment efficacy. This suggests a potential role in monitoring PD-L1 expression indirect biomarkers (i.e. miR-320a, miR-145 and CD73) during ICIs treatment.

ΔNp63 regulates MDSC survival and metabolism in triple-negative breast cancer

Triple-negative breast cancer (TNBC) contributes greatly to mortality of breast cancer, demanding new targetable options. We have shown that TNBC patients have high ΔNp63 expression in tumors. However, the function of ΔNp63 in established TNBC is yet to be explored. In current studies, targeting ΔNp63 with inducible CRISPR knockout and Histone deacetylase inhibitor Quisinostat showed that ΔNp63 is important for tumor progression and metastasis in established tumors by promoting myeloid-derived suppressor cell (MDSC) survival through tumor necrosis factor alpha. Decreasing ΔNp63 levels are associated with decreased CD4+ and FOXP3+ T-cells but increased CD8+ T-cells. RNA sequencing analysis indicates that loss of ΔNp63 alters multiple MDSC properties such as lipid metabolism, chemotaxis, migration, and neutrophil degranulation besides survival. We further demonstrated that targeting ΔNp63 sensitizes chemotherapy. Overall, we showed that ΔNp63 reprograms the MDSC-mediated immunosuppressive functions in TNBC, highlighting the benefit of targeting ΔNp63 in chemotherapy-resistant TNBC.

Long noncoding RNA LINC00885 upregulates NCK1 to promote cell viability and migration of triple-negative breast cancer cells through sponging miR-654-3p.

LINC00885 is a novel oncogenic long noncoding RNA (LncRNA) which is upregulated in various types of cancer, but its function in triple-negative breast cancer (TNBC) remains unknown. This study aimed to determine the role of LINC00885 on TNBC development. Clinical interrelation and survival analysis were determined using online database. The CCK-8 and Transwell assays were used to detect the proliferation and migration behaviors in TNBC cell lines. The interaction among genes was detected by RNA pull down assay. LncRNA LINC00885 was highly expressed in TNBC compared to normal breast like. Low levels of LINC00885 was related to good prognosis in TNBC patients compared to TNBC patients with high LINC00885. LINC00885-downregulation inhibited, whereas LINC00885-overexpression promoted the proliferation and migration capability of TNBC cell lines. In TNBC cell lines, noncatalytic region of tyrosine kinase 1 (NCK1) expression was positively associated with LINC00885 expression, and shRNA-mediated the depletion of NCK1 significantly abolished LINC00885 upregulation-mediated pro-tumor effects. Combined with online databases, miR-654-3p was screened as the direct target gene of LINC00885, which could directly bind to 3'-untranslated regions (3'-UTR) of NCK1, resulting in the decreased expression of NCK1 in TNBC cell lines. LINC00885 overexpression-mediated the upregulation of NCK1 was abrogated by miR-654-3p mimics. MiR-654-3p mimics significantly rescued the tumor promotive role caused by LINC00885-overexpression. However, exogenous NCK1 notably eliminated the anti-tumor effects caused by miR-654-3p mimics in LINC00885-overexpressed cells. LINC00885 is expressed at a high level in TNBC. LINC00885 promoted proliferation and migration by regulating the miR-654-3p/NCK1 axis in TNBC cell lines. Possibly, LINC00885 can be served as a potential therapeutic target for TNBC.

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

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

High dose Vitamin C inhibits PD-L1 by ROS-pSTAT3 signal pathway and enhances T cell function in TNBC

Vitamin C (VitC) presents excellent anti-tumor effect for long time. Recently, high dose VitC achieved by intravenous administration manifests superior anti-tumor effect. However, the functions and detailed mechanisms of high dose VitC’s role in cancer immunity are not fully understood. This study investigates the effect of high dose VitC on PD-L1 expression in triple negative breast cancer (TNBC) and the potential mechanism. Results showed VitC inhibited PD-L1 expression in breast cancer cell lines and enhanced anti-tumor effects of T cells. Furthermore, we found VitC inhibited PD-L1 transcription through ROS-pSTAT3 signal pathways. Consistent with in vitro results, in vivo study showed VitC suppressed tumor growth in immunocompetent mice and enhanced CD8+ T cells infiltration and function in tumor microenvironment. Our findings identify the effects of high dose VitC on PD-L1 expression and provide a rationale for the use of high dose VitC as immunomodulator for cancer therapy.

Nrf3 promotes the proliferation and migration of triple‑negative breast cancer by activating PI3K/AKT/mTOR and epithelial‑mesenchymal transition.

Nuclear factor erythroid 2-related factor 3 (Nrf3) is increasingly implicated in multiple types of cancer; however, its function in triple-negative breast cancer (TNBC) remains unclear. This study aimed to examine the role of Nrf3 in TNBC. Compared with adjacent normal tissues, TNBC tissues expressed higher levels of Nrf3, and its expression was negatively correlated with survival time. Additionally, Nrf3 knockdown reduced the proliferation and migration of TNBC cells, whereas overexpression of Nrf3 had the opposite effects in vitro and in vivo. Moreover, functional enrichment of TNBC cells overexpressing Nrf3 allowed for the identification of numerous genes and pathways that were altered following Nrf3 overexpression. Further study showed that overexpression of Nrf3 activated the PI3K/AKT/mTOR signaling pathway and regulated the expression of proteins associated with epithelial-mesenchymal transition. Nrf3 was found to directly bind to p110α promoter regions, as evidenced by luciferase reporter and chromatin immunoprecipitation assays. Furthermore, PI3K inhibitors partially decreased the proliferation and migration of the Nrf3 overexpressing TNBC cells. In conclusion, Nrf3 enhances cellular proliferation and migration by activating PI3K/AKT/mTOR signaling pathways, highlighting a novel therapeutic target for TNBC.

An EZH2-NF-κB regulatory axis drives expression of pro-oncogenic gene signatures in triple negative breast cancer

The histone methyltransferase EZH2 has been studied most extensively in the context of PRC2-dependent gene repression. Accumulating evidence indicates non-canonical functions for EZH2 in cancer contexts including promoting paradoxical gene expression through interactions with transcription factors, including NF-κB in triple negative breast cancer (TNBC). We profile EZH2 and NF-κB factor co-localization and positive gene regulation genome-wide, and define a subset of NF-κB targets and genes associated with oncogenic functions in TNBC that is enriched in patient datasets. We demonstrate interaction between EZH2 and RelA requiring the recently identified transactivation domain (TAD) which mediates EZH2 recruitment to, and activation of certain NF-κB-dependent genes, and supports downstream migration and stemness phenotypes in TNBC cells. Interestingly, EZH2-NF-κB positive regulation of genes and stemness does not require PRC2. This study provides new insight into pro-oncogenic regulatory functions for EZH2 in breast cancer through PRC2-independent, and NF-κB-dependent regulatory mechanisms.

CircRNA_0001006 predicts prognosis and regulates cellular processes of triple-negative breast cancer via miR-424-5p

Backgroundcircular RNAs (circRNAs) have been considered novel biomarker candidates for human cancers, such as triple-negative breast cancer (TNBC). circ_0001006 was identified as a differentially expressed circRNA in metastatic breast cancer, but its significance and function in TNBC were unclear. The significance of circ_0001006 in TNBC was assessed and exploring its potential molecular mechanism to provide a therapeutic target for TNBC.Resultscirc_0001006 showed significant upregulation in TNBC and close association with patients’ histological grade, Ki67 level, and TNM stage. Upregulated circ_0001006 could predict a worse prognosis and high risk of TNBC patients. In TNBC cells, silencing circ_0001006 suppressed cell proliferation, migration, and invasion. In mechanism, circ_0001006 could negatively regulate miR-424-5p, which mediated the inhibition of cellular processes by circ_0001006 knockdown.ConclusionsUpregulated circ_0001006 in TNBC served as a poor prognosis predictor and tumor promoter via negatively regulating miR-424-5p.

Silencing Notch4 promotes tumorigenesis and inhibits metastasis of triple-negative breast cancer via Nanog and Cdc42

Elucidation of individual Notch protein biology in specific cancer is crucial to develop safe, effective, and tumor-selective Notch-targeting therapeutic reagents for clinical use [1]. Here, we explored the Notch4 function in triple-negative breast cancer (TNBC). We found that silencing Notch4 enhanced tumorigenic ability in TNBC cells via upregulating Nanog expression, a pluripotency factor of embryonic stem cells. Intriguingly, silencing Notch4 in TNBC cells suppressed metastasis via downregulating Cdc42 expression, a key molecular for cell polarity formation. Notably, downregulation of Cdc42 expression affected Vimentin distribution, but not Vimentin expression to inhibit EMT shift. Collectively, our results show that silencing Notch4 enhances tumorigenesis and inhibits metastasis in TNBC, indicating that targeting Notch4 may not be a potential strategy for drug discovery in TNBC.

Abstract 2681: Combination therapy of heme inhibitory protein (HeSP2) and Cyclopamine tartrate (CycT) with chemotherapeutic drugs is an effective strategy for treatment of TNBC

Abstract Breast cancer (BC) is the second leading cause of cancer death in women. Among the four main types of BC, triple-negative breast cancer (TNBC) accounts for 10 to 15% of BC. Although most TNBC patients have a poor prognosis, there are subsets of patients with tumors that respond well to chemotherapy. However, the outcome of chemotherapy in TNBC worsens over time due to the high expression of the oxidative phosphorylation (OXPHOS) complex. Likewise, drug resistant TNBC cells depend on OXPHOS; targeting oxidative metabolism and mitochondrial respiration can potentially overcome their drug resistance. Our lab recently engineered a heme-sequestering protein 2 (HeSP2) based on HasA hemophore. HeSP2 can effectively inhibit heme uptake and decrease the OXPHOS levels in cancer cells due to its high affinity for heme. Another agent, cyclopamine tartrate (CycT), previously known as a modulator of hedgehog signaling and mitochondrial respiration, can inhibit heme synthesis and reduce the OXPHOS levels. Therefore, using these heme-targeting agents in combination with chemotherapy could be an effective strategy to increase the therapeutic efficacy in TNBC. Cisplatin and etoposide are two chemotherapeutic drugs that have recently been used for treating TNBC. For this purpose, we examine the combination therapy of our OXPHOS inhibitory agents, HeSP2 and CycT, with cisplatin and etoposide in TNBC. In vitro experiment using three different TNBC cell lines, 4T1-Fluc-Neo, EMT6_Fluc_Puro, and MDA-MBA-231 confirmed the inhibitory effect of both HeSP2 and CycT in cell proliferation and colony formation in combination with or without chemo drugs. Results indicate that combination therapy significantly reduced the proliferation and inhibited colony formation in TNBC cells. As HeSP2 and CycT are therapeutic agents that reduce hypoxia and OXPHOS, they may also delay the emergence of drug resistance in cancer cells treated with chemotherapy. Our results indicate that HeSP2 and CycT in combination with chemotherapy drugs could serve as a promising therapy to diminish the tumorigenic function in TNBC and overcome resistance to chemotherapy. Citation Format: Parinaz Sadat Alemi, Maria del Carmen Chacon Castro, Eranda Berisha, Zakia Akter, Li Zhang. Combination therapy of heme inhibitory protein (HeSP2) and Cyclopamine tartrate (CycT) with chemotherapeutic drugs is an effective strategy for treatment of TNBC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2681.

Abstract P4-07-12: Development of Triple-negative breast cancer (TNBC) syngeneic models and TROP2-directed antibody-drug conjugate (ADC) surrogate to model therapeutic combinations

Abstract Background: Sacituzumab govitecan (SG, Trodelvy®) is a human trophoblast cell surface antigen 2 (TROP-2) directed antibody drug conjugate (ADC) coupled to an active form of irinotecan (SN-38) via our novel hydrolyzable linker (CL2A). SG is the only FDA-approved ADC treatment for TNBC patients in the second-line setting. TROP-2 is a transmembrane protein encoded by the tumor-associated calcium signal transducer 2 (TACSTD2) gene and highly expressed in TNBC, an aggressive type of cancer accounting for approximately 15% of all breast cancers. TROP-2 overexpression is associated with poor survival and relapse, but its biological function in TNBC remains poorly understood. Hypothesis/rationale: To better understand TROP-2 and TROP-2-directed ADC biology, we developed and characterized TROP2high vs TROP2low TNBC syngeneic tumors and an SG surrogate directed to murine TROP-2. Experimental design: We established 2 syngeneic TNBC models with differential TROP-2 expression: 4T1 cells were flow sorted into high (>95%) vs low (< 7%) TROP-2 expressors and EMT6 cells were transduced with a murine TACSTD2-encoding lentivirus. Balb/c mice were subcutaneously implanted with 0.5 × 10 E6 TROP-2high, TROP-2low, or parental tumor cells (4T1 or EMT6). Tumor immunophenotyping and transcriptomic analyses were performed 15 and 24 days after implantation. An SG mouse surrogate was engineered to mimic SG, using an anti-TROP-2 antibody (Rab64) that cross-reacts with human and murine TROP-2 covalently attached to SN-38 by the CL2A linker. SG surrogate activity was characterized in vitro and in 4T1 syngeneic models. Results: SG surrogate demonstrated high affinity for human and mouse TROP-2 (KD=1.1 and 1.4 nM, respectively) with SN-38 release rates and PK similar to that of SG. Flow cytometry analysis after bulk cell sorting of 4T1 or lentivirus transduction of EMT6 confirmed high TROP2 expression after at least 3 in vitro passages. Fifteen days after subcutaneous implantation, flow cytometry analysis of tumor single-cell suspensions revealed significant differences in immune infiltrates between 4T1-derived tumor groups (n=5/group; mean percentages in TROP2high vs TROP2low 4T1-derived tumors of cells expressing CD45: 65% vs 10%, P < 0.0001; CD8: 5.5% vs 1%, P = 0.0033; CD4: 22% vs 4%, P = 0.0055; macrophages: 12.5% vs 2.5%, P = 0.0002; myeloid cells: 52% vs 75%, P = 0.0066). In addition, TROP2high 4T1-derived tumors were smaller and had significantly less necrosis than TROP2low and unsorted 4T1-derived tumors 25 days after implantation. Finally, transcriptomics analyses of TROP2high vs TROP2low 4T1-derived tumors demonstrated the association of TACSTD2 expression levels with regulation of distinct molecular pathways. Conclusion: Syngeneic tumors derived from 4T1 cells with differential TROP2 expression levels are associated with differential cellular states and tumor microenvironment composition. In contrast, no significant phenotypic changes were observed in tumors derived from TACSTD2-transduced compared with mock-transduced EMT6 cells. Taken together, these results suggest that expression of the TACSTD2 gene is associated with, but not causative of, different tumor phenotypic states. Additional studies to investigate TROP-2 expression as a correlative marker of patient prognosis and the antitumor immune response are warranted. The effects of in vivo treatment with an SG surrogate on 4T1 tumor growth and immune phenotype will be discussed at the time of the presentation. Citation Format: Chih-Chien Chou, Jordan Kardos, Becky Yang, Jessica Orf, Rutwij Dave, Yurong Lai, Chingwei V. Lee, Giuseppe A. Papalia, Kelli Boyd, Lauri Diehl, Nathalie Scholler. Development of Triple-negative breast cancer (TNBC) syngeneic models and TROP2-directed antibody-drug conjugate (ADC) surrogate to model therapeutic combinations [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-12.

Phosphorylation of USP29 by CDK1 Governs TWIST1 Stability and Oncogenic Functions.

Triple-negative breast cancer (TNBC) is a highly lethal malignancy with limited therapy options. TWIST1, a key transcriptional factor of epithelial-mesenchymal transition (EMT), contributes to self-renewal of cancer stem-like cells (CSCs), chemo-resistance, metastasis, and TNBC-related death. However, the mechanism by which TWIST1 is deregulated in TNBC remains elusive. Here, USP29 is identified as a bona fide deubiquitinase of TWIST1. The deubiquitination of TWIST1 catalyzed by USP29 is required for its stabilization and subsequent EMT and CSC functions in TNBC, thereby conferring chemotherapeutic resistance and metastasis. Furthermore, the results unexpectedly reveal that CDK1 functions as the direct USP29 activator. Mechanistically, CDK1-mediated phosphorylation of USP29 is essential for its deubiquitinase activity toward TWIST1 and TWIST1 driven-malignant phenotypes in TNBC, which could be markedly mitigated by the genetic ablation or pharmacological inhibition of CDK1. Moreover, the histological analyses show that CDK1 and USP29 are highly upregulated in TNBC samples, which positively correlate with the expression of TWIST1. Taken together, the findings reveal a previously unrecognized tumor-promoting function and clinical significance of the CDK1-USP29 axis through stabilizing TWIST1 and provide the preclinical evidence that targeting this axis is an appealing therapeutic strategy to conquer chemo-resistance and metastasis in TNBC.

Isoproterenol-induced Upregulation of HPSE Accelerates Triple-negative Breast Cancer Cell Proliferation and Migration through Enhancing the Transcriptional Activity of HIF-1α.

Triple-negative breast cancer (TNBC) is considered to be the most malignant subtype of breast cancer (BC). Heparanase (HPSE) has been reported to contribute to tumor development, but its potential function in TNBC is not clear. The intention of this study was to investigate whether HPSE affects TNBC progression and to explore the possible mechanisms. Bioinformatics analyses were applied to analyze the expression of HPSE in TNBC samples and normal breast samples. The mRNA and protein levels of HPSE in TNBC cells were detected by RT-qPCR and western blot. Function assays, including CCK-8 assay, colony formation assay, transwell assay and wound healing assay, were conducted to validate the effects of HPSE silencing on TNBC cell proliferation and migration. Mechanism experiments were performed to explore the upstream molecular mechanism of HPSE in TNBC cells. Silencing of HPSE suppressed the proliferation and migration of TNBC cells. Moreover, hypoxia-inducible factor-1 alpha (HIF-1α) interacted with the HPSE promoter and promoted the transcription of HPSE. Isoproterenol (ISO), a pharmacological substitute for chronic stress-induced sympathetic activation, was proven to induce HIF-1α upregulation, so as to transcriptionally activate HPSE in TNBC cells. Furthermore, it manifested that ISO facilitated TNBC cell proliferation and migration in an HPSE-dependent way. HPSE activated by ISO-induced HIF-1α promoted TNBC cell proliferation and migration, which might offer a novel insight for TNBC treatment.

PGRMC1 promotes triple-negative breast cancer cell growth via suppressing ferroptosis

Objective Triple-negative breast cancer (TNBC) is the most malignant form of breast cancer with increasing incidence and mortality worldwide. The progesterone receptor membrane component-1 (PGRMC1) is a well-identified hormone receptor with unknown functions in TNBC. The current study aims to explore the involvement of PGRMC1 in regulation of glutathione metabolism and ferroptosis during development of TNBC, providing new therapy options for TNBC patients. Methods Bioinformatic analysis, cell proliferation assay, western blot assay and other biochemistry methods were performed in TNBC cells. Results Our results revealed that the expression of PGRMC1 is higher in TNBC than the other subtypes of breast cancer. Interestingly, as an iron binding protein, increased PGRMC1 expression in TNBC cells leads to resistance to ferroptosis inducer. On the contrary, silenced PGRMC1 expression enhanced sensitivity of MDA-MB231 cells to Erastin. Mechanistically, overexpression of PGRMC1 decreased the intracellular free iron concentration, which was reduced by AG205 treatment. Conclusions PGRMC1 increases the possibility of TNBC development through binding to intracellular iron and suppressing ferroptosis, providing the molecular basis of combined treatment for TNBC.

CircAR-E2E4-miR-665-STAT3 axis is a potential regulatory network in triple-negative breast cancer

Circular RNAs (circRNAs) are a novel type of endogenous non-coding RNAs (ncRNA). Many studies showed that circRNAs played different biological functions in triple-negative breast cancer (TNBC). However, the potential molecular mechanism of circRNAs in TNBC still remains to be investigated. In this study, circAR-E2E4 was defined as a novel circRNA involved in TNBC progression, derived from and regulated by androgen receptor (AR). CCK-8 assay showed circAR-E2E4 regulated TNBC cell proliferation. Potential binding miRNAs of circAR-E2E4 were predicted and miR-665 was identified to have a great prognosis value. Three databases were employed to predict target genes of miR-665, and STAT3 was regarded as the most potential downstream genes analyzed by protein-protein interaction (PPI), hub gene screening, correlation analysis, and survival analysis. Finally, knockdown of circAR-E2E4 led to the decrease of STAT3 expression. Collectively, the regulatory network circAR-E2E4-miR-665-STAT3 axis we constructed was associated with TNBC progression, providing a promising diagnostic, prognostic, and therapeutic target in future treatment for TNBC.

USP22 Contributes to Chemoresistance, Stemness, and EMT Phenotype of Triple-Negative Breast Cancer Cells by egulating the Warburg Effect via c-Myc Deubiquitination

BackgroundUbiquitin-specific protease 22 (USP22) has been implicated in the progression of breast cancer, while its regulatory functions in triple-negative breast cancer (TNBC) have been rarely reported. This study aimed to elucidate the effect and mechanism of USP22 on the malignant phenotype of TNBC cells. Materials and MethodsThe expression of USP22, stemness genes, and EMT-related markers were analyzed by RT-qPCR and/or Western blotting. Cell stemness was determined by cell spheroid formation, flow cytometry for CD44+/CD24-, and extreme limiting dilution analysis. Cell proliferation and cisplatin (DDP) chemoresistance of TNBC cells were assessed by CCK-8 assay and xenograft model. Glycolysis was measured by Seahorse assay. The mechanism underlying the role of USP22 was explored by Co-immunoprecipitation, ubiquitination assay, and cycloheximide-chase analysis. ResultsUSP22 expression was positively correlated with DDP resistance in TNBC patients and cells. The proliferation, spheroid number, CD44+/CD24- cells, the expression of stemness genes and EMT-related markers in TNBC cells were significantly elevated after USP22 was overexpressed; however, these parameters in DDP-resistant TNBC (TNBC/DDP) cells were significantly reduced after silencing USP22. USP22 overexpression enhanced the extracellular acidification rate, proliferation, spheroid number, CD44+/CD24- cell number, and the expression of stemness genes and EMT-related markers in TNBC/DDP cells, while these effects were restrained by glycolysis inhibitors. Mechanically, USP22 interacted with c-Myc to promote its stabilization by deubiquitination in TNBC cells. Silencing of USP22 increased DDP sensitivity and survival of mice bearing TNBC. ConclusionUSP22 contributes to chemoresistance, stemness, and EMT phenotype of TNBC cells by suppressing the glycolysis via c-Myc deubiquitination.

HC-1119, a deuterated Enzalutamide, inhibits Migration, Invasion and Metastasis of the AR-positive triple-negative breast Cancer cells

Triple-negative breast cancers (TNBCs) are aggressive, and they develop metastasis at earlier stages, relapse more frequently, and exhibits poorer prognosis than other subtypes of breast cancer. Due to the lack of estrogen receptor for endocrine therapy and HER2 for targeted therapy, new targeted therapies for TNBCs are urgently needed. Enzalutamide is a second-generation androgen receptor (AR) inhibitor, and HC-1119 is a new synthetic deuterated enzalutamide. Owing to the isotope effect, HC-1119 has many advantages over enzalutamide, including slow metabolism, high plasma concentration and low brain exposure. However, the efficacy of HC-1119 in inhibition of AR function in triple-negative breast cancer (TNBC) has not been studied. In this study, we found high-level AR expression in both Hs578T and SUM159PT TNBC cell lines. Activation of AR by dihydrotestosterone (DHT) in both cell lines increased AR protein, induced AR-nuclear localization, enhanced cell migration and invasion in culture, and promoted liver metastasis in mice. Importantly, cotreatment with HC-1119 of these cells efficiently abolished all of these effects of DHT on both Hs578T and SUM159PT cells. These results indicate that HC-1119 is a very effective new second-generation AR antagonist that can inhibit the migration, invasion and metastasis of the AR-positive TNBC cells.

Comparative analysis of transient receptor potential channel 5 opposite strand-induced gene expression patterns and protein-protein interactions in triple-negative breast cancer.

In patients with triple-negative breast cancer (TNBC), high tumour mutation burden and aberrant oncogene expression profiles are some of the causes of poor prognosis. Therefore, it is necessary to identify aberrantly expressed oncogenes, since they have the potential to serve as therapeutic targets. Transient receptor potential channel 5 opposite strand (TRPC5OS) has been previously shown to function as a novel tumour inducer. However, the underlying mechanism of TRPC5OS function in TNBC remain to be elucidated. Therefore, in the present study TRPC5OS expression was first measured in tissue samples of patients with TNBC and a panel of breast cancer cell lines (ZR-75-1, MDA-MB-453, SK-BR-3, JIMT-1, BT474 and HCC1937) by using qRT-PCR and Western blotting. Subsequently, the possible effects of TRPC5OS on MDA-MB-231 cells proliferation were determined using Cell Counting Kit-8 and 5-Ethynyl-2′-deoxyuridine assays after Lentiviral transfection of MDA-MB-231. In addition, potential interaction partners of TRPC5OS were explored using liquid chromatography-mass spectrometry (LC-MS)/MS. Gene expression patterns following TRPC5OS overexpression were also detected in MDA-MB-231 cells by using High-throughput sequencing. Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) analysis were then used to systematically verify the potential interactions among the TRPC5OS-regulated genes. The potential relationship between TRPC5OS-interacting proteins and gene expression patterns were studied using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis. TRPC5OS expression was found to be significantly higher in TNBC tumour tissues and breast cancer cell lines compared with luminal tumour tissues and ZR-75-1. In addition, the overexpression of TRPC5OS significantly increased cell proliferation. High-throughput sequencing results revealed that 5,256 genes exhibited differential expression following TRPC5OS overexpression, including 3,269 upregulated genes and 1,987 downregulated genes. GO analysis results indicated that the functions of these differentially expressed genes were enriched in the categories of ‘cell division’ and ‘cell proliferation’ regulation. KEGG analysis showed that the TRPC5OS-regulated genes were associated with processes of ‘homologous recombination’ and ‘TNF signalling pathways’. Subsequently, 17 TRPC5OS-interacting proteins were found using LC-MS/MS and STRING analysis. The most important protein among interacting proteins was ENO1 which was associated with glycolysis and regulated proliferation of cancer. In summary, data from the present study suggest that TRPC5OS overexpression can increase TNBC cell proliferation and ENO1 may be a potential target protein mediated by TRPC5OS. Therefore, TRPC5OS may serve as a novel therapeutic target for TNBC.

HUNK Regulation of Interleukin 4 in Triple Negative Breast Cancer

Triple‐negative breast cancer (TNBC) is a type of breast cancer that does not express hormone receptors (estrogen receptor or progesterone receptor) or human epidermal growth factor receptor 2. Therefore, contrary to other types of breast cancer, TNBC is not sensitive to endocrine therapy or HER2 targeted inhibitors. Some new FDA approve as treatments for TNBC include immunotherapy targets such as immune checkpoint inhibitor (ICI). Unfortunately, inadequate anti‐tumor T‐cell effector function and high abundances of tumor‐associated macrophages (TAMs) has limited the efficacy of ICI therapy. TAMs constituted one of the most abundant immune cell population in mammary tumors. Within the tumor TAMS can be polarized to classicallyactivatedM1‐like and alternativelyactiveM2‐likephenotypes.M2‐likemacrophagescontribute to cancer progression by inducing tumor angiogenic responses, promoting tumor growth and metastasis. In cancer the polarization of macrophages toward a M2 phenotype is directed by cancer‐cell derived factors such as pleiotropic cytokines like interleukin‐4 (IL‐4). New knowledge suggests that IL‐4 expression in cancer cells is regulated by the signal transducer and activator of transcription 3 (STAT3) transcription factor. However, it is still undescribed what signaling pathways are responsible for mediating IL‐4 in breast cancer cells. Intriguingly, we observed that Hormonally Up‐Regulated Neu‐Associated Kinase (HUNK), is responsible for IL‐4 production in the 4T1 mammary tumor cell line, which is considered a metastatic TNBC model. We hypothesis that HUNK regulation of IL‐4 drives TAM’s polarization in triple negative breast cancer cells. We engineered4T1 cells expressing HUNK and HUNK knockdown by shRNA. Our current data shown that4T1 cells expressing HUNK, have elevated levels of STAT3 phosphorylation, IL‐4 production and secretion compared to 4T1 cells where HUNK has been downregulated by shRNA. Furthermore, the loss of IL‐4 secretion in 4T1 HUNK knockdown cells corresponds to a reduced ability of conditioned medium from HUNK knockdown cells to induce alternative activation of macrophages. We also observed that HUNK has a significant effect on M2‐likeTAMspresence in the tumor microenvironment, where tumors derived from HUNK knockdown 4T1 cells have reduced TAMs compared to control tumors. Therefore, our results proposed the identification of a HUNK signaling pathway that is responsible for pro‐metastatic TAM function in TNBC. Our study will evaluate HUNK as a therapeutic target for TNBC metastasis by modulating the TAM population within the tumor microenvironment.