The study demonstrates that TFEB regulates the expression of the multidrug efflux transporter ATP-binding cassette subfamily G member 2 (ABCG2), a crucial factor in drug resistance mechanisms, and targets TNKS represents a potentially effective therapeutic approach to address cisplatin resistance and improve treatment outcomes in TNBC.
Triple negative breast cancer (TNBC) continues to have a poor prognosis relative to other forms of this disease. Previous studies have shown that the HOX family of transcription factors generally show increased expression in breast cancer and may have a primarily pro-oncogenic role. In this study, we assessed the sensitivity of a range of TNBC-derived cell lines to an inhibitor of HOX protein function, HTL-001, which blocks the interaction between HOX proteins and the Pre-B-cell Leukaemia Homeobox (PBX) cofactor. The sensitivity of cell lines was measured by MTS viability assays, and gene expression by RT-qPCR. Combination studies were performed with epigenetic modifiers (5-azacytidine (5-aza), Trichostatin A (TSA)) and standard-of-care chemotherapeutic drugs including Paclitaxel. A mouse tumour flank model of MDA-MB-231 cells was used to assess response to HTL-001, paclitaxel, or combination therapy. All the cell lines exhibited high levels of HOX dysregulation compared to an immortalised line derived from normal breast cells, and greater sensitivity to HTL-001-induced apoptosis. Epigenetic changes have previously been shown to be key modulators of HOX expression and, correspondingly, we show that reversing epigenetic changes in these cell lines significantly alters HOX expression and generally reduces sensitivity to HTL-001. In addition, HTL-001 shows synergistic interactions with several established chemotherapeutic agents in vitro. We further demonstrate that HTL-001 can significantly reduce tumour growth in a mouse model of TNBC. Our findings indicate that HOX/PBX dimers are a potential therapeutic target in this cancer.
Richard Morgan, G. Simpson, E. Arunachalam et al.· Current Issues in Molecular...· 0 citations
Triple-negative breast cancer (TNBC) is an aggressive subtype characterized by significant intratumoral heterogeneity and poor prognosis. Our study identified Establishment Factor-Like Protein 2 (EFO2) as a key oncogenic driver of TNBC progression. Using GEO datasets, we identified differentially expressed genes in TNBC. Functional roles of EFO2 were assessed via knockdown in human (MDA-MB-231, HCC1937) and mouse (4 T1, EMT6) TNBC cells, examining proliferation, glycolysis, and co-culture with CD8⁺ T cells. In vivo tumor growth was evaluated. Molecular mechanisms were investigated through co-immunoprecipitation, mutagenesis, luciferase reporter, and ChIP-qPCR assays. We observed that EFO2 was highly expressed in TNBC tissues, and this high expression correlated with shorter patient survival. Functional experiments showed that EFO2 knockdown suppressed tumor growth and proliferation both in vitro and in vivo. Furthermore, EFO2 knockdown inhibited glycolysis, as evidenced by decreased glucose uptake, ATP production, and lactate production. Moreover, EFO2 deficiency enhanced CD8⁺ T cell-mediated cytotoxicity against TNBC cells. Mechanistically, we demonstrated that EFO2 promoted the acetylation of Upstream Transcription Factor 1 (USF1), thereby enhancing transcriptional upregulation of the SLC2A1 promoter, a key glucose transporter. This EFO2/USF1/SLC2A1 signaling axis accelerated glycolysis in TNBC cells, which concurrently sustained tumor proliferation and impaired CD8⁺ T cell effector function, reducing TNBC cell susceptibility to T cell-mediated killing. Our findings identify a novel EFO2/USF1/SLC2A1 signaling axis that modulates glycolytic metabolism and CD8⁺T cell cytotoxicity, positioning EFO2 as a promising therapeutic target for TNBC treatment.
Lin Jia, Liru Li, Junning Peng et al.· Biochemical Pharmacology· 0 citations
In MCF-7 and MDA-MB-231 cells, TBX20 overexpression significantly enhanced cell proliferation, migration, invasion, and resistance to doxorubicin, while suppressing the expression of mitophagy-related proteins LC3-II/LC3-I, PINK1, and BNIP3.
Shuai Nie, Dejian Liu, Jun Hu et al.· PLoS ONE· 0 citations
: Objectives: As an aggressive subtype of breast cancer, triple-negative breast cancer (TNBC) is constrained by the limited availability of effective treatments and the absence of well-validated therapeutic targets. This study aimed to explore whether honokiol, a potent YAP/TAZ inhibitor, suppresses stem cell–like properties and enhances chemotherapeutic efficacy in TNBC by blocking YAP/TAZ–TEAD transcriptional complex. Meth-ods: Through both in vitro and in vivo models of TNBC, the current study examined how honokiol influences cell proliferation, cancer stem cell (CSC) traits, and paclitaxel sensitivity. To uncover the molecular mechanisms, we analyzed the transcript levels and protein abundance of core YAP/TAZ–TEAD pathway members, including YAP, TAZ, TEADs, ANKRD1, and CYR61. Furthermore, we conducted immunofluorescence staining to examine the nuclear localization of YAP/TAZ. Potential direct interactions were identified using molecular docking, which also predicted the binding affinity between honokiol and the TAZ–TEAD complex. Results: Honokiol markedly suppressed the viability and stemness of TNBC cells. It also improved the antitumor efficacy of paclitaxel in both TNBC cells and xenograft models. Mechanistically, honokiol may directly target the TAZ–TEAD complex, as indicated by molecular docking analysis. This interaction led to decreased YAP/TAZ protein levels and blockade of their nuclear accumulation, thereby suppressing the downstream transcriptional targets ANKRD1 and CYR61 in TNBC cells. Conclusion: Collectively, our findings suggest that honokiol is a promising therapeutic agent against TNBC, acting at least in part by suppressing the transcriptional activity of the YAP/TAZ–TEAD complex, thus attenuating cancer stemness and overcoming chemoresistance. These findings highlight honokiol’s translational potential.
BACKGROUND
Triple-negative breast cancer (TNBC) is a clinically challenging disease subtype of breast cancer, with therapeutic outcomes remaining unsatisfactory due to its highly invasive potential. Ferroptosis, a newly identified type of programmed cell death, is mediated by the iron-dependent accumulation of lipid peroxides, presenting a potential therapeutic avenue for the treatment of TNBC. Calycosin (Cal) has demonstrated antitumor effects across various tumors; however, its therapeutic potential based on the ferroptosis pathway for TNBC treatment and the associated mechanisms remains unclear.
METHODS
To achieve this, the cell counting kit-8 assay, flow cytometry assay, wound healing assay, colony formation assay, EdU assay, and xenograft mouse models were performed. Mechanisms were investigated using transcriptomic sequencing, quantitative reverse transcription polymerase chain reaction, and Western blot in vitro and in vivo.
RESULTS
Our findings indicated that Cal significantly reduces the viability of TNBC cells, primarily manifested as suppression of growth, migration, and colony formation through the induction of ferroptosis. Additionally, Cal impairs mitochondrial function in TNBC cells by reducing mitochondrial membrane potential and elevating ferroptosis-related markers, including MDA and 4-HNE accumulation, reactive oxygen species formation, and GSH depletion. Mechanistically, Cal administration may reduce GPX4 levels through the OTUD6B-mediated ubiquitination pathway, thereby enhancing the ubiquitination and degradation of the GPX4 protein. The decreased OTUD6B and GPX4 expression significantly inhibited TNBC growth both in vivo and in vitro, resulting in ferroptosis induction in TNBC cells.
CONCLUSION
This is the first study to demonstrate that Cal exerts anti-TNBC activity through a novel OTUD6B/GPX4-dependent ferroptosis regulatory axis. These findings highlight that Cal warrants further investigation as a potential candidate, and the OTUD6B/GPX4 signaling pathway may represent a significant target for TNBC treatment.
Xue Mao, Yin Lin, Zhifeng Gu et al.· Biochemical and Biophysical...· 0 citations
