Figure 5

MYB and ZEB1 expression are inversely correlated in various in vivo and in vitro biologic settings. (A) MYB expression is reduced in EMT. (i) Exposure of MDA-MB-468 cells to hypoxia (1% oxygen) for up to 5 days led to significant (*P < 0.05, repeated measures one-way ANOVA with Dunnet multiple comparison test) induction of the hypoxia-indicator gene carbonic anhydrase 9 (CAIX) and significant EMT-related gene changes, including the induction of ZEB1 and repression of MYB. (ii) Treatment of PMC42-LA cells with 10 ng/ml EGF for 9 days (EGF-containing media replenished every 3 days) induced an EMT in which ZEB1 expression was significantly (*P < 0.05, Student paired t test) induced and MYB repressed. For both (i) and (ii), results shown are QRT-PCR data, expressed as fold change (corrected to untreated cells), of three independent experiments, and error bars represent SEM. Morphologic changes of MDA-MB-468 cells exposed to hypoxia and EGF-treated PMC42-LA are found in Additional file 5A and B, respectively. Further evidence of MYB-expression reduction in EMT is found in Additional file 6A and B. (B) Plot of expression of MYB across various breast tumors of increasing aggressiveness, using data derived from a publically available microarray dataset [50]. (C) MYB tumoral staining correlates with CDH1 and inversely correlates with VIM in (i) matched human breast tumor primary (Primary T) and sentinel lymph node metastases (LN MET); and in (ii) nonrelated human breast cancer bone metastases. Magnification 400×; scale bar, 150 μm. Findings further supported by IHC shown in Additional file 5D.