Fig. 4

PRRG4 regulates mtDNA content and mitochondrial function through STAT3. A Stattic decreases mtDNA content enhanced by PRRG4 overexpression in breast cancer cells. Cells with PRRG4 overexpression were treated with vehicle or Stattic (3 µM for MDA-MB-231, and 2 µM for HCC1954 cells) for 20 h before being subjected to qPCR analysis for mtDNA content. B Overexpression of a dominant negative STAT3 mutant (STAT3-DN) decreases mtDNA content in SUM149PT cells. C Overexpression of PRRG4 increases the basal ATP (Base) and oligomycin-sensitive ATP (Oligo-sensitive) contents through STAT3. Cells with PRRG4-WT were treated with vehicle or Stattic (3 µM for MDA-MB-231, and 2 µM for HCC1954 cells) for 20 h. Cells were treated with 1 µg/mL oligomycin for 1 h. D Overexpression of PRRG4 increases the basal, ATP-linked respiration (oligo-sensitive), and maximum respiratory capacity (FCCP) through STAT3. MDA-MB-231 cells were treated with vehicle or Stattic (3 µM) for 20 h. The basal, ATP-linked respiration, and maximum respiratory capacity were calculated in response to treatment with oligomycin (0.08 µg/mL) and FCCP (0.08 µM), respectively. *p < 0.05, **p < 0.01, ***p < 0.001