JNK activation is critical for Aplidin-induced apoptosis.
Aplidin is an antitumor drug that induces apoptosis and activates EGFR, Src, JNK and p38MAPK. Here, we show that Aplidin induces c-JUN, JUN B, JUN D, c-FOS, FRA-1 and FOS B genes of the activator-protein (AP)-1 family, and also p65/RELA, a major component of nuclear factor-kappa B (NF-kappaB). Concordantly, Aplidin increases AP-1 and NF-kappaB activity. c-FOS induction depends on EGFR, Src and JNK/p38MAPK. In contrast, induction of c-JUN does not require EGFR activity and p65/RELA induction is only partially dependent on these kinases. We used several genetically deficient cells to identify the critical target of Aplidin. Mouse embryo fibroblasts (MEFs) deficient for src, yes and fyn, and those lacking all p38MAPK isoforms displayed normal Aplidin sensitivity (IC50=12 nM). In contrast, MEFs lacking jnk1 and jnk2, which do not express any JNK isoform, were much less sensitive (IC50>500 nM). Furthermore, cells lacking c-jun or expressing a c-Jun protein in which JNK targets Ser(63/73) were mutated (c-JunAA) showed intermediate sensitivity (IC50=60 nM). Additionally, Aplidin has higher cytotoxic activity against proliferating than quiescent cells, which is reflected in higher JNK activation. We conclude that phosphorylation by JNK of c-Jun and additional substrate(s) is crucial for Aplidin activity.
Cuadrado
Ana
A
Pharma Mar SA, E-28770 Colmenar Viejo, Madrid, Spain.
González
Laura
L
Suárez
Yajaira
Y
Martínez
Teresa
T
Muñoz
Alberto
A
D000911:Antibodies, Monoclonal / Q000378:metabolism; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism; D002455:Cell Division; D045744:Cell Line, Tumor; D002470:Cell Survival; D047630:Depsipeptides; D004789:Enzyme Activation; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D010456:Peptides, Cyclic / Q000633:toxicity*; D010766:Phosphorylation; D011233:Precipitin Tests; D016755:Proto-Oncogene Proteins c-jun / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000187:drug effects / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D047630:Depsipeptides; D016328:NF-kappa B; D010456:Peptides, Cyclic; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D020928:Mitogen-Activated Protein Kinases; C098980:plitidepsin