Fig. 4: IDA regulates XPA protein levels by enhancing XPA protein degradation.

A LNCaP/ABI and 22RV1/ABI cells were treated with DMSO, IDA (0.25 μM), ABI (10 μM), and a combination of IDA with ABI for 24 h. XPA mRNA expression was determined by Real-time PCR (n = 4). B, C LNCaP/ABI (B) and 22RV1/ABI (C) cells were treated with CHX (100 mM) alone or in a combination of IDA (0.25 μM) in the presence of ABI(10 μM) for the indicated periods. Band densities were determined by Image-J software, and the value at time-point 0 was set as 100%. D LNCaP/ABI and 22RV1/ABI cells were treated with DMSO, MG132, and CQ(30 μM) with or without IDA(0.25 μM) for 24 h. XPA protein levels were determined by western blot. E LNCaP/ABI and 22RV1/ABI cells were treated with DMSO, IDA(0.25 μM), ABI(10 μM), and a combination of IDA with ABI for 24 h. LC3B expressions were determined by western blot assay. F LNCaP/ABI cells were treated with DMSO, IDA(0.25 μM), ABI(10 μM), ABI plus IDA for 20 h. Proteasome inhibitor MG132 (1 μM) was included in the assay to protect the ubiquitinated protein from degradation. Ubiquitination of XPA was determined by western blot. Data are presented as means ± s.e.m. Statistical analysis was performed using two-way ANOVA analysis (Two-way ANOVA, *p < 0.05).