TL;DR
CAG modulates the cell cycle and EMT through the EZH2/PTEN/AKT pathway, effectively overcoming Tmab resistance in HER2-positive BC cells.
BACKGROUND Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC) with limited treatment options. Paclitaxel (PTX) is commonly used, but its effectiveness is hampered by resistance and metastasis. The c-Met receptor, which is often upregulated in TNBC, promotes tumor progression via the HGF/c-Met axis and downstream PI3K/AKT and MAPK pathways. This study explored whether Capmatinib (CAP), a selective c-Met inhibitor, can enhance PTX efficacy in TNBC. METHODS MDA-MB-231 and 4T1 TNBC cell lines were treated with PTX and CAP, alone and in combination. Cytotoxicity, apoptosis, and cell cycle effects were assessed via MTT assays and flow cytometry. Cell migration was evaluated via scratch assays. The expression of epithelial-mesenchymal transition (EMT) markers (E-cadherin, vimentin, and Snail) was measured via real-time PCR. In vivo studies in BALB/c mice have evaluated hematological parameters, poor prognostic gene expression (BCL11, FOXC1, FOXM1), histopathology, and survival. RESULTS In MDA-MB-231 cells, combination therapy increased PTX cytotoxicity, induced G2/M arrest, increased apoptosis, and suppressed migration. Co-treatment upregulated E-cadherin and downregulated vimentin and Snail. A weak synergistic effect was observed in 4T1 cells. In vivo, co-treatment improved hematological indices, reduced the expression of genes related to poor prognosis, inhibited angiogenesis and necrosis, increased lymphocyte infiltration, and prolonged survival. CONCLUSION CAP enhances the antitumor activity of PTX in TNBC by targeting c-Met-mediated pathways. This combination therapy shows potential to overcome resistance and improve treatment outcomes in TNBC.
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.
OBJECTIVE To identify targetable pathways that can overcome resistance to trastuzumab deruxtecan (T-DXd) in endometrial cancer. METHODS We used four endometrial cancer cell lines with different genetic backgrounds (KLE, HEC-1B, Ishikawa, and AN3 CA). Patient-derived endometrial organoids were established from surgically resected tumors and maintained in basement membrane extract with optimized media. Drug interactions were evaluated using Bliss synergy modeling. Organoid growth and treatment response were quantified by imaging-based size measurements. Protein signaling changes were analyzed by immunoblotting and comprehensive phosphoproteomic profiling. Cell cycle effects were assessed by flow cytometry. In vivo efficacy was evaluated using HEC-1B xenograft models treated with T-DXd and trametinib alone or in combination. Immunohistochemistry was performed on tumor and organoid samples to assess pathway activation and proliferation markers. Statistical analyses were conducted using GraphPad Prism 9, R and Python packages. RESULTS T-DXd treatment increases ERK1/2 activation and reduces HER2 expression across various endometrial cancer cell lines. The addition of trametinib, a MEK1/2 inhibitor, to T-DXd, restores HER2 expression and markedly reduces the growth of both endometrial cancer cell lines (in vitro and in vivo), and organoids. Phosphoproteomic assays showed that T-DXd increases phosphorylation of proteins involved in DNA damage and the cell cycle, including ATR. We also found that ERK1/2 plays a key role in activating ATR and causing cell cycle arrest in the G2/M phase. CONCLUSION T-DXd activates ERK1/2 and ATR, which contributes to resistance, and combining T-DXd with a MEK1/2 inhibitor enhances treatment response.