Dominant negative MEKK1 inhibits survival of pancreatic cancer cells.
Human pancreatic cancers harbor mutations in the K-ras gene, and these mutations convert the gene oncogenic and constitutively active forms. However, in pancreatic cancer cells little is known about the activation of the downstream pathways of Ras, MEK-ERK and MEKK1-JNK, and their roles in cell survival and proliferation. An analysis of nine pancreatic cancer tissues revealed JNK activation in all tumor samples and ERK activation in three tumor samples. Colony formation assays by transfection of dominant negative mutants of Ras, ERK or MEKK1 into pancreatic cancer cell lines (BxPC-3, PANC-1, MIAPaCa-2 and AsPC-1) and an amnion-derived cell line (FL) revealed that DN-MEKK strongly inhibits the survival of colonies in pancreatic cancer cells, but not in FL cells. In vitro kinase assays and luciferase assays using the Gal4c-Jun system revealed that in pancreatic cancer cells DN-MEKK fails to inhibit JNK activation. In PANC-1 cells, c-Jun was found to be a major component of protein component binding to AP-1 site and CRE, but not in FL cells. The inhibitory effect of DN-MEKK in PANC-1 cells was thought to be the result of the inhibition of c-Jun DNA-binding. The difference of suppression in pancreatic cancer cells and non-pancreatic cancer cells suggested that the MEKK1 pathway mainly contributes to cell survival in pancreatic cancer cells and may provide an advantage for the gene therapy of pancreatic cancers using DN-MEKK expression vectors.
Hirano
Tatsuya
T
Department of Medicine and Clinical Oncology (K1), Graduate School of Medicine, Chiba University, Japan.
Shino
Yuji
Y
Saito
Takeshi
T
Komoda
Fumitake
F
Okutomi
Yoshiyuki
Y
Takeda
Akiko
A
Ishihara
Takeshi
T
Yamaguchi
Taketo
T
Saisho
Hiromitsu
H
Shirasawa
Hiroshi
H
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D002470:Cell Survival / Q000235:genetics; D005260:Female; D005799:Genes, Dominant; D011905:Genes, ras; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; D008297:Male; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism*; D012016:Reference Values; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human