Figure 2. Forced expression of TFF3 activated HER signalling activity, while inhibition of TFF3 by AMPC decreased HER signalling activity in BT474 cells.

(A) BT474-VEC and -TFF3 cells were generated. (B) BT474 cells were treated with the indicated concentrations of TFF3 inhibitor AMPC in media supplemented with 5% FBS. Subsequently, the levels of TFF3, phosphorylated and total HER receptors and downstream signalling mediators were analysed using western blot. β-ACTIN was used as input control. The densitometric analyses of protein bands were performed using ImageJ. (C) Activated HER2 decreased TFF3 expression, which in turn reduced TFF3-mediated activation of HER2 signalling in a negative feedback loop. (D) Trastuzumab inhibition of HER2 increased TFF3 expression to compensate for the loss of HER2 signalling.