In many cases, the process of
cancer cell differentiation is associated with the programmed cell death. In the present study, interestingly, we found that
eupatilin, one of the pharmacologically active ingredients of Artemisia asiatica that has been reported to induce apoptosis in human
gastric cancer AGS cells, also triggers differentiation of these cells. Treatment of AGS cells with
eupatilin induced cell cycle arrest at the G(1) phase with the concomitant induction of p21(cip1), a cell cycle inhibitor. This led us to test whether
eupatilin may trigger AGS cells to differentiate into the matured phenotypes of epithelial cells and this phenomenon may be coupled to the apoptosis.
Eupatilin induced changes of AGS cells to a more flattened morphology with increased cell size, granularity, and mitochondrial mass. It also markedly induced
trefoil factor 1 (TFF1), a gene responsible for the gastrointestinal cell differentiation.
Eupatilin dramatically induced redistribution of
tight junction proteins such as
occludin and ZO-1, and
F-actin at the junctional region between cells. It also induced phosphorylation of
extracellular signal-regulated kinase 2 and p38
kinase. Blockade of ERK signaling by
PD098059 or the dominant-negative ERK2 significantly reduced
eupatilin-induced TFF1 and p21 expression as well as ZO-1 redistribution, indicating that ERK cascades may mediate
eupatilin-induced AGS cell differentiation. Collectively, our results suggest that
eupatilin acts as a novel anti-
tumor agent by inducing differentiation of
gastrointestinal cancer cells rather than its direct role in inducing apoptotic cell death.