Activation of nonsteroidal anti-inflammatory drug-activated gene-1 via extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase revealed a isochaihulactone-triggered apoptotic pathway in human lung cancer A549 cells.
The novel lignan isochaihulactone inhibits cell proliferation and is an effective inducer of apoptosis in a variety of carcinoma cell lines. To determine the mechanisms underlying these effects, we examined isochaihulactone-induced changes in gene expression using oligodeoxynucleotide-based microarray screening of a human lung carcinoma cell line, A549. Isochaihulactone-inducible genes included the early growth response gene-1 (EGR-1) and nonsteroidal anti-inflammatory drug-activated gene (NAG-1). Isochaihulactone increased EGR-1 and then NAG-1 mRNA and protein expression. Pure isochaihulactone induced phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. Isochaihulactone-induced increases in EGR-1 and NAG-1 expression were reduced by the mitogen-activated protein kinase kinase 1/2 inhibitor 2'-amino-3'-methoxyflavone (PD98059), and this effect was not blocked by the phosphatidylinositol 3-kinase/protein kinase B pathway inhibitor 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002). Inhibition of isochaihulactone-induced NAG-1 expression by EGR-1 small interfering RNA blocked isochaihulactone-induced apoptosis in A549 cells, suggesting that induction of EGR-1 expression decreases survival of A549 cells. RNA interference using double-stranded RNA specific for NAG-1 also inhibited isochaihulactone-induced apoptosis, and cells transfected to increased NAG-1 expression had a greater apoptotic response to isochaihulactone and reduced colony formation efficiency. In addition, treatment of nude mice with isochaihulactone increased the in vivo NAG-1 expression as examined by immunohistochemistry from tumor biopsy. Isochaihulactone treatment increased the luciferase activity of NAG-1 in A549 cells transfected with the NAG-1 promoter construct. This induction increased expression of NAG-1 that was p53-independent and Sp1-dependent. Our findings suggest that NAG-1 expression is up-regulated by isochaihulactone through an ERK-dependent pathway involving the activation of EGR-1.
Chen
Yi-Lin
YL
Graduate Institute of Biotechnology, National Ilan University, Ilan, Taiwan, Republic of China.
Lin
Po-Cheng
PC
Chen
Shee-Ping
SP
Lin
Chai-Ching
CC
Tsai
Nu-Man
NM
Cheng
Yeung-Leung
YL
Chang
Wen-Liang
WL
Lin
Shinn-Zong
SZ
Harn
Horng-Jyh
HJ
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D052117:Benzodioxoles / Q000494:pharmacology*; D045744:Cell Line, Tumor; D016207:Cytokines / Q000235:genetics*; D051766:Early Growth Response Protein 1 / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D055436:Growth Differentiation Factor 15; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000502:physiology; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011401:Promoter Regions, Genetic
D000970:Antineoplastic Agents; D052117:Benzodioxoles; D016207:Cytokines; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C526140:GDF15 protein, human; C526141:Gdf15 protein, mouse; D055436:Growth Differentiation Factor 15; C512868:isochaihulactone; D019869:Phosphatidylinositol 3-Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D015107:4-Butyrolactone