Figure 2.

Loss of RECQL4 is associated with resistance to taxanes and spontaneous DNA damage response activation. (A): IHC performed with anti-RECQL4 antibody in ER-positive/HER2-negative tumors (61 cases) and ER-negative/HER2-negative tumors (39 cases). RECQL4 was expressed to higher levels in ER-negative/HER2-negative tumors (p = .0264). (B): Death of RECQL4-silenced cells compared with scrambled or untransfected control cells after taxane treatment (1 μM or 4 μM) (*p < .001). Error bars indicate the standard deviation (SD; n = 3). (C): Survival of RECQL4-silenced cells compared with untransfected or BRCA1 siRNA control cells after PARP inhibition (*p < .001). (D): Immunoblot analysis of protein knockdown 96 hours after transfection of control, RECQL4, and BRCA1 siRNA constructs. (E): Nontargeting and RECQL4 siRNA were transfected into MDA-MB-231 cells, and γH2AX foci were counted 96 hours after transfection (mock, transfection with no siRNA) (*p < .001). Error bars represent the SD (n = 3).

Abbreviations: IHC, immunohistochemistry; siRNA, small interfering RNA.