nirmatrelvir  (MedChemExpress)

Journal: Translational Cancer Research

Article Title: Targeting the METTL3/PCNA axis with STM2457 overcomes cisplatin resistance in osteosarcoma

doi: 10.21037/tcr-2025-1429

Figure Lengend Snippet: STM2457 inhibits proliferation and synergizes with cisplatin in cisplatin-resistant OS cells. (A) Dose-response curves of STM2457 (0–20 µM, 48 hours) on cell viability in MG-63/DDP and U2OS/DDP cells, as determined by CCK-8 assay. IC 50 values are shown as mean ± SD (n=3; **, P<0.01 vs. untreated control for MG-63/DD; ## , P<0.01 vs. untreated control for U2OS/DDP). (B) CI analysis of STM2457 (10 µM) and cisplatin (10 µM) treatment for 48 hours. Synergistic effects (CI <1) are highlighted. Data represent mean ± SD (n=3; **, P<0.01; ***, P<0.001 vs. untreated control for MG-63/DDP; ## , P<0.01; ### , P<0.001 vs. untreated control for U2OS/DDP). CCK-8, Cell Counting Kit-8; CI, combination index; Cis, cisplatin; ns, not significant; IC 50 , half-maximal inhibitory concentration; OS, osteosarcoma; SD, standard deviation.

Article Snippet: STM2457 (Cat# HY-138687, MedChemExpress, Monmouth Junction, NJ, USA) was dissolved in dimethyl sulfoxide (DMSO, Sigma-Aldrich) and stored at −80 °C.

Techniques: CCK-8 Assay, Control, Cell Counting, Concentration Assay, Standard Deviation

Journal: Translational Cancer Research

Article Title: Targeting the METTL3/PCNA axis with STM2457 overcomes cisplatin resistance in osteosarcoma

doi: 10.21037/tcr-2025-1429

Figure Lengend Snippet: STM2457 enhances cisplatin-induced apoptosis in resistant OS cells. (A) Representative immunofluorescence images showing cleaved Caspase-3 (green), nuclear morphology (Hoechst, blue), and merged views. White arrows indicate apoptotic cells with nuclear fragmentation. Scale bar: 50 µm. (B) Quantification of apoptotic rates. Data are presented as mean ± SD (n=3; *, P<0.05; ***, P<0.001 vs. control for MG-63/DDP; # , P<0.05; ### , P<0.001 vs. control for U2OS/DDP). DAPI, 4',6-diamidino-2-phenylindole; ns, not significant; OS, osteosarcoma; SD, standard deviation.

Article Snippet: STM2457 (Cat# HY-138687, MedChemExpress, Monmouth Junction, NJ, USA) was dissolved in dimethyl sulfoxide (DMSO, Sigma-Aldrich) and stored at −80 °C.

Techniques: Immunofluorescence, Control, Standard Deviation

Journal: Translational Cancer Research

Article Title: Targeting the METTL3/PCNA axis with STM2457 overcomes cisplatin resistance in osteosarcoma

doi: 10.21037/tcr-2025-1429

Figure Lengend Snippet: STM2457 suppresses migration capacity of cisplatin-resistant OS cells. (A) Representative immunofluorescence images showing vimentin (red), nuclear morphology (Hoechst, blue), and merged views. White arrows indicate apoptotic cells with nuclear fragmentation. Scale bar: 50 µm. (B) Quantitative analysis of vimentin-positive cells. Data are mean ± SD (n=3; **, P<0.01; ***, P<0.001 vs. control for MG-63/DDP; ## , P<0.01; ### , P<0.001 vs. control for U2OS/DDP). DAPI, 4',6-diamidino-2-phenylindole; ns, not significant; OS, osteosarcoma; SD, standard deviation.

Article Snippet: STM2457 (Cat# HY-138687, MedChemExpress, Monmouth Junction, NJ, USA) was dissolved in dimethyl sulfoxide (DMSO, Sigma-Aldrich) and stored at −80 °C.

Techniques: Migration, Immunofluorescence, Control, Standard Deviation

Journal: Translational Cancer Research

Article Title: Targeting the METTL3/PCNA axis with STM2457 overcomes cisplatin resistance in osteosarcoma

doi: 10.21037/tcr-2025-1429

Figure Lengend Snippet: STM2457 downregulates PCNA via METTL3-dependent m6A methylation. (A) qRT-PCR analysis of PCNA mRNA levels in MG-63/DDP and U2OS/DDP cells treated with STM2457 (10 µM, 48 hours). GAPDH was used as a reference. Data are mean ± SD (n=3; *, P<0.05; ***, P<0.001 vs. control for MG-63/DDP; # , P<0.05; ### , P<0.001 vs. control for U2OS/DDP). (B) Western blot analysis of PCNA protein expression. (C) Densitometric quantification of PCNA protein levels normalized to β-actin. Data are mean ± SD (n=3; *, P<0.05; ***, P<0.001 vs. control for MG-63/DDP; # , P<0.05; ### , P<0.001 vs. control for U2OS/DDP). (D) Western blot analysis of METTL3 protein expression. (E) Densitometric quantification of METTL3 protein levels normalized to β-actin. Data are mean ± SD (n=3). (F) Global m6A RNA methylation levels measured by colorimetric assay in STM2457-treated cells (10 µM, 48 hours). Data are normalized to input RNA (mean ± SD, n=3; *, P<0.05 vs. control for MG-63/DDP; # , P<0.05 vs. control for U2OS/DDP). (G,H) PCNA mRNA stability assessed by qRT-PCR after actinomycin D (5 µg/mL) treatment in MG-63/DDP and U2OS/DDP cells under different treatments. Half-life (t 1/2 ) was calculated from decay curves (mean ± SD, n=3). GAPDH, glyceraldehyde-3-phosphate dehydrogenase; METTL3, methyltransferase-like 3; mRNA, messenger RNA; ns, not significant; PCNA, proliferating cell nuclear antigen; qRT-PCR, quantitative real-time polymerase chain reaction; SD, standard deviation.

Article Snippet: STM2457 (Cat# HY-138687, MedChemExpress, Monmouth Junction, NJ, USA) was dissolved in dimethyl sulfoxide (DMSO, Sigma-Aldrich) and stored at −80 °C.

Techniques: Methylation, Quantitative RT-PCR, Control, Western Blot, Expressing, Colorimetric Assay, Real-time Polymerase Chain Reaction, Standard Deviation

Journal: Translational Cancer Research

Article Title: Targeting the METTL3/PCNA axis with STM2457 overcomes cisplatin resistance in osteosarcoma

doi: 10.21037/tcr-2025-1429

Figure Lengend Snippet: PCNA is a critical functional mediator of STM2457’s anti-tumor effects in cisplatin-resistant osteosarcoma cells. (A) Cell viability after siRNA-mediated PCNA knockdown (si-PCNA) or STM2457 (10 µM) treatment in MG-63/DDP and U2OS/DDP cells (CCK-8 assay; mean ± SD, n=3; **, P<0.01 vs. si-NC for MG-63/DDP; ## , P<0.01 vs. si-NC for U2OS/DDP). (B,C) Immunofluorescence images (B) and quantification (C) of apoptosis (cleaved Caspase-3 staining): PCNA overexpression decreased STM2457-induced apoptosis. Data are mean ± SD (n=3; **, P<0.01 vs. vector + NC for MG-63/DDP; ## , P<0.01 vs. vector + NC for U2OS/DDP). (D,E) Representative immunofluorescence images (D) and quantification (E) of migration capacity (vimentin-positive cells). PCNA overexpression restored STM2457-inhibited migration. Scale bar: 50 µm. Data are mean ± SD (n=3; *, P<0.05 vs. vector + NC for MG-63/DDP; # , P<0.05 vs. vector + NC for U2OS/DDP). (F) Cisplatin resistance restoration: PCNA overexpression increased cisplatin IC 50 , diminishing STM2457’s chemosensitization effect. Data are mean ± SD (n=3; ***, P<0.001 vs. vector + Cis for MG-63/DDP; ### , P<0.001 vs. vector + Cis for U2OS/DDP). White arrows indicate apoptotic cells with nuclear fragmentation. CCK-8, Cell Counting Kit-8; Cis, cisplatin; DAPI, 4',6-diamidino-2-phenylindole; IC 50 , half-maximal inhibitory concentration; NC, negative control; ns, not significant; PCNA, proliferating cell nuclear antigen; SD, standard deviation; si-NC, scrambled negative control siRNA.

Article Snippet: STM2457 (Cat# HY-138687, MedChemExpress, Monmouth Junction, NJ, USA) was dissolved in dimethyl sulfoxide (DMSO, Sigma-Aldrich) and stored at −80 °C.

Techniques: Functional Assay, Knockdown, CCK-8 Assay, Immunofluorescence, Staining, Over Expression, Plasmid Preparation, Migration, Cell Counting, Concentration Assay, Negative Control, Standard Deviation