Molecular inhibitory mechanism of phospholipase D signaling against anticancer drug-induced apoptosis in stomach cancer cellsMolecular inhibitory mechanism of phospholipase D signaling against anticancer drug-induced apoptosis in stomach cancer cells

초록

Phspholipase D (PLD) catalyses the hydrolysis of the phosphodiester bond of phosphatidylcholine to generate phosphatidic acid and free head group, choline. There are at least two PLD isozymes, PLD1 and PLD2. Genetic and pharmacological approaches implicate both of PLD isozymes in a diverse range of cellular processes that include receptor signaling, control of intracellular membrane transport, and reorganization of the actin cytoskeleton. Several recent studies reported that PLD has a role in signaling pathways that oppose apoptosis and promote cell survival in cancer. In this study, we examined the role of PLD activity in anticancer drug-induced apoptosis in stomach cell lines. At first we made an anticancer drug spectra of normal stomach cell (NSC) and stomach cancer cell lines (SNU484) after treatment of seven different kinds of anticancer drug that are using for cure of cancer patients. We tested PLD activity of NSC and SNU484 after treatment with taxotere which was selected according to anticancer drug spectra on these cells. As results SNU484 has a low basal PLD1 and PLD2 expression. Taxotere treatment resulted in increasing not only PLDs expression but also PLD activity. When PLD was selectively inhibited by pretreating the cells with 1-butanol, taxotere-induced apoptosis was exacerbated in both of NSC and SNU484. We constructed stable stomach cell lines using Retro-virus construction system for overexpression of PLD isozymes (PLD 1 and 2) to elucidate the role of PLD during taxotere-induced apoptosis. These stably transfected cell lines resulted in inhibition of taxotere-induced apoptotic cell death, evidenced by notably decreased apoptotic cell death in PLDs-introduced SNU 484 cells even though in the presence of seven different kinds of anticancer drug for 24 h and inhibited degradation of chromosomal DNA unlike that in GFP-control cells. We also found that Bcl-2 expression was up-regulated and taxotere-induced activation of procaspase-3 was inhibited after transfection of PLD1 and PLD2 in SNU484. Taken together, these results indicate that PLD plays protective role against taxotere-induced cell death in SNU 484 cells through up-regulation of Bcl-2 expression.