Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025019
Cancer cells evade immune detection through checkpoint molecules like PD-L1 and PD-L2 which suppress T-cell activation. While PD-L1 is well-studied, the role of PD-L2 remains unclear. Pyruvate kinase M2 (PKM2), a metabolic enzyme, influences immune checkpoint regulation, but its role in PD-L1 and PD-L2 modulation is not well defined. Here, we investigate the role of pyruvate kinase M2 (PKM2) in modulating the immune checkpoint molecules PD-L1 and PD-L2 via GATA3 in cancer cells, with insights from both human and mouse models. We find that PKM2 enhances PD-L1 expression while inhibiting PD-L2, a dual regulatory mechanism that facilitates immune evasion. Knockdown and overexpression experiments revealed GATA3 as a key mediator. PKM2 knockout reduced GATA3 level, leading to decreased PD-L1 and increased PD-L2 expression. Chromatin immunoprecipitation (ChIP)-qPCR demonstrates that GATA3 functions as a direct transcription factor capable of binding to the promoters of PD-L1 and PD-L2. In silico analyses of 81 esophageal squamous cell carcinoma (ESCC) cases from the TCGA database demonstrate that PKM2 mRNA is unrelated to PD-L1 and PD-L2 expression but is negatively correlated with CD8+ T-cell infiltration in ESCC. To further validate these findings, we establish a xenograft model using immune-competent C57/BL6N mice, where knockdown of PKM2 results in significant downregulation of both PD-L1 and PD-L2 expression. Collectively, these findings underscore the divergent roles of PKM2 in regulating immune checkpoint expression in human and mouse cancer models and suggest that targeting the PKM2-GATA3 axis could enhance cancer immunotherapy by fine-tuning PD-L1 and PD-L2 levels.
Chinese Journal of Tissue Engineering Research•2026•DOI: 10.12307/2026.21447
BACKGROUND: Neobavaisoflavone could promote bone formation and may be a potential small molecule drug for bone regeneration. The use of 3D printed bone tissue engineering scaffolds as drug delivery carriers for neobavaisoflavone is expected to enhance the potential application of bone regeneration. OBJECTIVE: To explore the effects of polylactic acid/polydopamine/neobavaisoflavone bone scaffold on osteoclast and osteoblast activity. METHODS: (1) Fused deposition modeling technology was used to manufacture a 3D printed polylactic acid scaffold. These polylactic acid scaffolds were immersed in a dopamine solution containing or without neobavaisoflavone to produce polylactic acid/polydopamine/neobavaisoflavone scaffolds and polylactic acid/polydopamine scaffolds, respectively. The surface morphology, surface hardness, and compressive strength of the three groups of scaffolds were characterized, and the drug release properties of the polylactic acid/polydopamine/neobavaisoflavone scaffolds were investigated. (2) Mouse embryonic osteoblast MC3T3-E1 cells were co-cultured with the three groups of scaffolds. CCK-8 assay and live/dead staining were used to evaluate the cytocompatibility of the scaffolds. Transwell assay was used to evaluate the effect of scaffolds on osteoblast migration. Alkaline phosphatase quantitative assay and alizarin red staining were used to evaluate the effect of scaffolds on osteoblast differentiation. RAW264.7 cells were co-cultured with the three groups of scaffolds. After osteoclast induction, tartrate-resistant acid phosphatase staining was used to evaluate the effect of scaffolds on osteoclast differentiation. RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that all three groups of scaffolds had three-dimensional structure and regular interconnected porous structure with an average pore size of 400 µm. The surface hardness and compressive strength of polylactic acid/polydopamine scaffolds and polylactic acid/polydopamine/neobavaisoflavone scaffolds were higher than those of polylactic acid scaffolds (P < 0.05). Polylactic acid/polydopamine/neobavaisoflavone scaffolds had good drug release behavior and could continuously release drugs for more than 14 days in vitro. (2) CCK-8 assay and live/dead staining showed that all three groups of scaffolds had good cytocompatibility, and polylactic acid/polydopamine scaffolds and polylactic acid/polydopamine/neobavaisoflavone scaffolds could promote MC3T3-E1 cell proliferation. Transwell assay showed that compared with polylactic acid scaffolds, polylactic acid/polydopamine scaffolds and polylactic acid/polydopamine/neobavaisoflavone scaffolds could promote MC3T3-E1 cell migration. Alkaline phosphatase quantitative assay and alizarin red staining showed that compared with the other two groups, polylactic acid/polydopamine scaffolds and polylactic acid/polydopamine/neobavaisoflavone scaffolds could promote osteogenic differentiation of MC3T3-E1 cells. Tartrate-resistant acid phosphatase staining showed that polylactic acid/polydopamine/neobavaisoflavone scaffolds could inhibit osteoclast differentiation of RAW264.7 cells. (3) These results indicate that polylactic acid/polydopamine/neobavaisoflavone scaffolds have good biosafety and can promote bone regeneration by regulating osteoblast and osteoclast activities.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025019
Cancer cells evade immune detection through checkpoint molecules PD-L1 and PD-L2, which suppress T-cell activation. While PD-L1 is well-studied, the role of PD-L2 remains unclear. Pyruvate kinase M2 (PKM2), a metabolic enzyme, influences immune checkpoint regulation, but its role in PD-L1 and PD-L2 modulation is not well defined. Here, we investigate the role of PKM2 in modulating PD-L1 and PD-L2 via GATA3 in cancer cells, with insights from both human and mouse models. We find that PKM2 enhances PD-L1 expression while inhibiting PD-L2, a dual regulatory mechanism that facilitates immune evasion. Knockdown and overexpression experiments revealed GATA3 as a key mediator. PKM2 knockout reduced GATA3 level, leading to decreased PD-L1 and increased PD-L2 expression. Chromatin immunoprecipitation (ChIP)-qPCR demonstrates that GATA3 functions as a direct transcription factor capable of binding to the promoters of PD-L1 and PD-L2. In silico analyses of 81 esophageal squamous cell carcinoma (ESCC) cases from the TCGA database demonstrate that PKM2 mRNA is unrelated to PD-L1 and PD-L2 expression but is negatively correlated with CD8+ T-cell infiltration in ESCC. To further validate these findings, we establish a xenograft model using immune-competent C57/BL6N mice, where knockdown of PKM2 results in significant downregulation of both PD-L1 and PD-L2 expression. Collectively, these findings underscore the divergent roles of PKM2 in regulating immune checkpoint expression in human and mouse cancer models and suggest that targeting the PKM2-GATA3 axis could enhance cancer immunotherapy by fine-tuning PD-L1 and PD-L2 levels.