Fig. 4

A positive feedback loop between ID3 and PPARγ enhances the radiosensitivity of colorectal cancer cells. A Western blotting (left panel) and statistical analysis (right panel) of PPARγ expression in HCT116 cells with ID3 knockdown or overexpression. PPARγ was negatively correlated with the expression of ID3. B Western blotting (left panel) and statistical analysis (right panel) of ID3 expression in HCT116 cells treated with PPARγ agonist pioglitazone hydrochloride (PH) or PPARγ inhibitor T0070907. After PPARγ activation, ID3 decreased, while after PPARγ inhibition, ID3 increased. C Lysates of HCT116 cells were subjected to co-immunoprecipitation using an anti-Myc antibody followed by western blotting (left panel) using anti-PPARγ and anti-ID3 antibodies. A statistical graph is located on its right. The result showed that MDC1 interacted with ID3. D Western blotting (left panel) and statistical analysis (right panel) of ID3 and PPARγ expression in HCT116-NC and HCT116-Id3 KD cells after irradiation. β-actin was used as a loading control. After ID3 depletion, irradiation could no longer affect PPARγ expression. E Clonogenic assay was used to assess the effect of ID3 depletion and PPARγ inhibitor T0070907 on the clonogenic activity of HCT116 cells after irradiation. F Statistical analysis of the surviving fraction in clonogenic assays. G. Comet tail moments in both control and ID3-depleted HCT116 cells after exposure to T0070907 and 6-Gy irradiation. Experiments were repeated at least three times. Data are expressed as mean ± SD (n = 3). ∗ P < 0.05.NC: siRNA control, PC: pcDNA3.1 control, KD: knockdown, OE: overexpress