Figure 2

PADI2 expression is elevated in luminal B BT-474 cells, murine MMTV-neu tumors, and is correlated with the luminal subtype. (a) Four different breast cancer cell lines were selected to represent the common subtypes of breast cancer: MCF7 (luminal A), BT-474 (luminal B), SK-BR-3 (HER2/ERBB2+), and MDA-MD-231 (basal). PADI2 expression is highest in both of the HER2/ERBB2 overexpressing cell lines, with the highest level seen in the luminal B BT-474 cells (ER+/PR+). (b) Relative PADI2 mRNA levels in the cell lines compared to MCF10A. (c) Tumors from MMTV-neu mice (luminal subtype) show a ~15-fold increase in PADI2 compared to normal mammary tissue. Both MMTV-Wnt-1 hyperplastic mammary tissue and tumors (basal subtype) show elevated levels of PADI2 compared to normal mammary tissue; however, PADI2 expression levels in MMTV-Wnt-1 tumors are ~10-fold less than those seen in the MMTV-neu tumors. PADI2 mRNA levels were determined by qRT-PCR (TaqMan) using MCF10A cells as a reference and GAPDH normalization. Expression levels were analyzed using the 2 ^{-ΔΔ C(t)} method, and data are expressed as the mean ± SD from three independent experiments (* p < 0.05, ** p < 1 × 10^-6). (d) RNA-seq analysis of 57 breast cancer cell lines shows that PADI2 expression is significantly higher in luminal lines versus basal (* p = 0.007) and higher in basal versus basal-NM/claudin-low (** p = 0.002).