Overexpression of phospholipase D suppresses taxotere-induced cell death in stomach cancer cells.
Phospholipase D (PLD) catalyzes the hydrolysis of phosphatidylcholine to generate phosphatidic acid (PA) and choline. There are at least two PLD isozymes, PLD1 and PLD2. Genetic and pharmacological approaches implicate both PLD isozymes in a diverse range of cellular processes, including receptor signaling, membrane transport control, and actin cytoskeleton reorganization. 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 in taxotere-induced apoptosis in stomach cell lines; normal stomach (NSC) and stomach cancer cells (SNU 484). Taxotere treatment resulted in increase of PLD activity. To confirm the role of PLD in taxotere-induced apoptosis, PLDs were transfected into SNU 484 cells. Overexpression of PLD isozymes resulted in inhibition of taxotere-induced apoptotic cell death, evidenced by decreased degradation of chromosomal DNA, and increased cell viability. Concurrently, Bcl-2 expression was upregulated, and taxotere-induced activation of procaspase 3 was inhibited after PLD's transfection. However, when PLD was selectively inhibited by specific siRNA-PLD1 or -PLD2, taxotere-induced apoptosis was exacerbated in SNU 484 cells. On top of this, PA -- the product of PLDs, also resulted in upregulation of Bcl-2 in SNU 484. Although PA-induced Bcl-2 expression was blocked by mepacrine, an inhibitor of phospholipase A(2) (PLA(2)), increased Bcl-2 expression by PA was not abrogated by propranolol, an inhibitor of PA phospholyhydrolase (PAP). Taken together, PLD1 and PLD2 are closely related with Bcl-2 expression together with PLA(2), but not with PAP, during taxotere-induced apoptosis in SNU 484 cells.
Cho
Ju Hwan
JH
Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul, Korea.
Hong
Seong-Kweon
SK
Kim
Eun-Young
EY
Park
Shin-Young
SY
Park
Chang-Hwan
CH
Kim
Jung Mogg
JM
Kwon
Oh Jung
OJ
Kwon
Sung-Joon
SJ
Lee
Ki-Sung
KS
Han
Joong-Soo
JS
D000970:Antineoplastic Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D017209:Apoptosis; D000077143:Docetaxel; D015870:Gene Expression; D006801:Humans; D010712:Phosphatidic Acids / Q000378:metabolism; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034622:RNA Interference; D013274:Stomach Neoplasms / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D043823:Taxoids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014162:Transfection
D000970:Antineoplastic Agents; D010712:Phosphatidic Acids; D019253:Proto-Oncogene Proteins c-bcl-2; D043823:Taxoids; D000077143:Docetaxel; C105606:phospholipase D2; D010739:Phospholipase D; C106801:phospholipase D1