Fig. 7.

TOP2A increase by doxorubicin treatment is influenced by lower miR-548c-3p and higher HuR levels. (A and C) Seventy-two hours after transfection with the small RNAs indicated, cells were treated with doxorubicin (1 μM) (A) or cisplatin (10 μM) (C) or left untreated; 24 h later, γ-H2AX, HuR, and β-actin levels were assessed by Western blot analysis and quantified by densitometry. (B) Cells were transfected with the small RNAs and/or plasmids indicated; 48 h later, cells were treated with Dox (1 μM), and the levels of γ-H2AX were assessed by Western blot analysis 24 h later. (D) Schematic of proposed antagonism between miR-548c-3p, which recruits TOP2A mRNA to microRNA-RISC repression machinery and enables Dox resistance (bottom), and HuR, which competes with miR-548c-3p and allows TOP2A translation to occur (top), as we postulate that TOP2A translation occurs during G₂/M and sensitizes cells to doxorubicin. For panels A to C, n = 3.