Evaluation of: Lee C, Dhillon J, Wang MY et al.: Targeting YB-1 in HER-2 overexpressing
breast cancer cells induces apoptosis via the mTOR/STAT3 pathway and suppresses
tumor growth in mice.
Cancer Res. 68 (21), 8661-8666 (2008). The
transcription factor Y-box
binding protein (YB)-1 is highly expressed in
breast cancer cells and is strongly linked with
breast cancer patient prognosis. In this paper,
siRNA knockdown of YB-1 was used to investigate
breast cancer cell proliferation. Six
breast cancer cell lines that either overexpress HER-2 or were triple negative demonstrated growth inhibition following YB-1 knockdown. In particular, YB-1 knockdown induced apoptosis in BT-474-m1 and Au565 cells. Knockdown of YB-1 also decreased phosphorylation of STAT3S727, ERK1/2T202/Y204, mTORS2448 and total mTOR expression. When STAT3 was knocked down by siSTAT3, apoptosis was induced and constitutively active phosphorylated STAT3 was found to rescue YB-1-induced apoptosis. Furthermore, YB-1 knockdown remarkably suppressed colony formation in a soft
agar assay, while delayed
tumor formation was observed in mice. YB-1 knockdown inhibited cell growth and it is thought to involve induction of apoptosis via the mTOR/STAT3 intracellular signaling pathway. YB-1 is a promising molecular target for HER-2-overexpressing or
triple-negative breast cancer cells.