title: Sustained activation of ERK and Cdk2/cyclin-A signaling pathway by pemetrexed leading to S-phase arrest and apoptosis in human non-small cell lung cancer A549 cells.
abstract: Pemetrexed, a multitargeted antifolate with the ability to inhibit several enzymes involved in purine and pyrimidine syntheses, has demonstrated clinical activity in non-small cell lung cancer cells, as well as in a broad array of other solid tumors. In this study, we show that inducing cell cycle S-phase arrest and apoptosis in human lung adenocarcinoma A549 cells with pemetrexed is associated with increased cyclin-A and cyclin-dependent kinase 2 (Cdk2) protein and Cdk2/cyclin-A kinase activity. Knockdown of cyclin-A using small interfering RNA (siRNA), and inhibiting Cdk2 activity with flavopiridol, strikingly reduced S-phase arrest and apoptosis. Moreover, pemetrexed induced sustained activation of extracellular signal-regulated kinase1/2 (ERK1/2). Knockdown of ERK1/2 using specific siRNA, as well as known inhibitors (PD98059 and U0126), effectively suppressed the expression of cyclin-A and Cdk2, and reduced S-phase arrest and apoptosis induced by pemetrexed. These data provide the first evidence that pemetrexed-induced S-phase arrest and apoptosis is associated with an increase in Cdk2 and cyclin-A expression and activation, which is ERK-dependent and upstream of caspase-3. Our findings suggest that the ERK-mediated Cdk2/cyclin-A signaling pathway is an important regulator of pemetrexed-induced S-phase arrest and apoptotic cell death.
authors.affiliation: Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung, Taiwan, Republic of China.
authors.forename: Tsung-Ying
authors.initials: TY
authors.lastname: Yang
authors.forename: Gee-Chen
authors.initials: GC
authors.lastname: Chang
authors.forename: Kun-Chieh
authors.initials: KC
authors.lastname: Chen
authors.forename: Hsiao-Wen
authors.initials: HW
authors.lastname: Hung
authors.forename: Kuo-Hsuan
authors.initials: KH
authors.lastname: Hsu
authors.forename: Gwo-Tarng
authors.initials: GT
authors.lastname: Sheu
authors.forename: Shih-Lan
authors.initials: SL
authors.lastname: Hsu
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology*; D045744:Cell Line, Tumor; D019925:Cyclin A / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005971:Glutamates / Q000494:pharmacology*; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008175:Lung Neoplasms / Q000473:pathology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D000068437:Pemetrexed; D016196:S Phase / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
chemical_list: D019925:Cyclin A; D005971:Glutamates; D047908:Intracellular Signaling Peptides and Proteins; D000068437:Pemetrexed; D006147:Guanine; D051357:Cyclin-Dependent Kinase 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3