Figure 3.

PER2 promotes the oxaliplatin sensitivity via impairing DNA adducts repair. a) Comet assay breaks. DNA strand breaks of globally oxaliplatin‐treated (30 µmol L⁻¹, 48 h). Breaks were quantified as % tail DNA and olive tail moment. At least 50 cells were analyzed per sample. b) Analysis of fluorescent protein expression from oxaliplatin‐incubated vector with cherry in OSCC cells (final concentration: 50 µmol L⁻¹, 12 h, at 37 °C). The vector with GFP was used as control. Scale bar, 100 µm. c) Representative confocal images of DDB2, ERCC1, and XRCC1 in PER2‐overexpressing or knockdown CAL27 cells. Scale bar, 20 µm. d) Western blot and densitometric quantification of the indicated proteins of DNA adducts repair markers in PER2‐overexpressing (left) or PER2‐knockdown (right) SCC15, SCC25, and CAL27 cells with oxaliplatin (20 µmol L⁻¹) treatment. GAPDH was used as the loading control. e) Western blot (left) and densitometric quantification (right) of the indicated proteins of DNA adducts repair markers in PER2‐knockdown or control CAL27 cells after treatment with oxaliplatin (L‐OHP, 20 µmol L⁻¹) with or without CHIR‐124 (0.3 nmol L⁻¹). f) Apoptosis was evaluated by flow cytometry of CAL27 cells after oxaliplatin (20 µmol L⁻¹) treatment with or without CHIR‐124 (0.3 nmol L⁻¹), Rabusertib (7 nmol L⁻¹), UPF1069 (0.3 µmol L⁻¹), or AG‐14361 (4 nmol L⁻¹). Cells stained with Annexin V and PI. g) Cell‐cycle phases were determined by flow cytometry of cells treated with oxaliplatin (20 µmol L⁻¹). h) The circadian oscillation of DDB2, ERCC1, XRCC1, and POL‐β mRNA levels in OSCC cells at the indicated time points. i) Western blot and densitometric quantification of the indicated proteins of DNA adducts repair markers in OSCC cells after treated with or without oxaliplatin (20 µmol L⁻¹) at indicated time points. GAPDH was used as the loading control. *P < 0.05, **P < 0.01, and ***P < 0.001 (compared with wild type). ANOVA was used. Data represent the mean ± SD of three independent experiments.