Pemetrexed induces S-phase arrest and apoptosis via a deregulated activation of Akt signaling pathway.
Pemetrexed is approved for first-line and maintenance treatment of patients with advanced or metastatic non-small-cell lung cancer (NSCLC). The protein kinase Akt/protein kinase B is a well-known regulator of cell survival which is activated by pemetrexed, but its role in pemetrexed-mediated cell death and its molecular mechanisms are unclear. This study showed that stimulation with pemetrexed induced S-phase arrest and cell apoptosis and a parallel increase in sustained Akt phosphorylation and nuclear accumulation in the NSCLC A549 cell line. Inhibition of Akt expression by Akt specific siRNA blocked S-phase arrest and protected cells from apoptosis, indicating an unexpected proapoptotic role of Akt in the pemetrexed-mediated toxicity. Treatment of A549 cells with pharmacological inhibitors of phosphatidylinositol 3-kinase (PI3K), wortmannin and Ly294002, similarly inhibited pemetrexed-induced S-phase arrest and apoptosis and Akt phosphorylation, indicating that PI3K is an upstream mediator of Akt and is involved in pemetrexed-mediated cell death. Previously, we identified cyclin A-associated cyclin-dependent kinase 2 (Cdk2) as the principal kinase that was required for pemetrexed-induced S-phase arrest and apoptosis. The current study showed that inhibition of Akt function and expression by pharmacological inhibitors as well as Akt siRNA drastically inhibited cyclin A/Cdk2 activation. These pemetrexed-mediated biological and molecular events were also observed in a H1299 cell line. Overall, our results indicate that, in contrast to its normal prosurvival role, the activated Akt plays a proapoptotic role in pemetrexed-mediated S-phase arrest and cell death through a mechanism that involves Cdk2/cyclin A activation.
Division of Chest Medicine, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China; Institute of Biomedical Science, National Chung Hsing University, Taichung, Taiwan, Republic of China.
Kun-Chieh
KC
Chen
Division of Chest Medicine, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China.
Tsung-Ying
TY
Yang
Institute of Medicine, Chung Shang Medical University, Taichung, Taiwan, Republic of China; Department of Medical Research, Chung-Shan Medical University Hospital, Taichung, Taiwan, Republic of China.
Chun-Chi
CC
Wu
Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China.
Chi-Chih
CC
Cheng
Department of Medical Research, Chung-Shan Medical University Hospital, Taichung, Taiwan, Republic of China; Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China; Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, Republic of China.
Shih-Lan
SL
Hsu
Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China.
Hsiao-Wen
HW
Hung
Institute of Biomedical Science, National Chung Hsing University, Taichung, Taiwan, Republic of China.
Jian-Wei
JW
Chen
Division of Chest Medicine, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China; Institute of Biomedical Science, National Chung Hsing University, Taichung, Taiwan, Republic of China; Department of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Gee-Chen
GC
Chang
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; 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; D000068437:Pemetrexed; D021381:Protein Transport / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*
D000970:Antineoplastic Agents; D019925:Cyclin A; D005971:Glutamates; D000068437:Pemetrexed; D006147:Guanine; D051057:Proto-Oncogene Proteins c-akt; D051357:Cyclin-Dependent Kinase 2