title: T-lymphokine-activated killer cell-originated protein kinase functions as a positive regulator of c-Jun-NH2-kinase 1 signaling and H-Ras-induced cell transformation.
abstract: T-lymphokine-activated killer cell-originated protein kinase (TOPK) is overexpressed in highly proliferating tumors such as leukemias and myelomas, and seems to play a key role in tumorigenesis or metastasis. However, the precise role and regulatory mechanism explaining the effects of TOPK on tumor cells still remain elusive. Here, we reported that TOPK regulates UVB-induced c-Jun-NH2-kinase 1 (JNK1) activity, and is essential for H-Ras-induced activator protein-1 activity and cell transformation. We showed that TOPK associated with and phosphorylated JNK1 following UVB irradiation in vitro or in vivo. Moreover, UVB-induced JNK1 activity was greatly augmented in mouse epidermal JB6 Cl41 cells that stably expressed TOPK cDNA. On the other hand, JNK1 activity was markedly attenuated by stable expression of small interfering RNA against TOPK in malignant melanoma RPMI 7951 cells. Interestingly, TOPK interacted with JNK-interacting protein 1 and caused an elevation of JNK-interacting protein 1 scaffolding activity, thereby enhancing JNK1 activity. Furthermore, JNK1 was required for TOPK-mediated activator protein-1 transcriptional activity and transformed foci induced by UVB or H-Ras. Taken together, these findings showed that TOPK positively modulated UVB-induced JNK1 activity and played a pivotal role in JNK1-mediated cell transformation induced by H-Ras. These studies might also provide a novel molecular mechanism for the role of TOPK in UVB-mediated skin carcinogenesis.
authors.affiliation: Hormel Institute, University of Minnesota, Austin, Minnesota.
authors.forename: Sang-Muk
authors.initials: SM
authors.lastname: Oh
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.forename: Yong-Yeon
authors.initials: YY
authors.lastname: Cho
authors.forename: Ki Won
authors.initials: KW
authors.lastname: Lee
authors.forename: Bong Seok
authors.initials: BS
authors.lastname: Kang
authors.forename: Hong-Gyum
authors.initials: HG
authors.lastname: Kim
authors.forename: Tatyana
authors.initials: T
authors.lastname: Zykova
authors.forename: Ann M
authors.initials: AM
authors.lastname: Bode
authors.forename: Zigang
authors.initials: Z
authors.lastname: Dong
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D004789:Enzyme Activation / Q000528:radiation effects; D011905:Genes, ras; D006801:Humans; D020935:MAP Kinase Signaling System; D008545:Melanoma / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D041701:Swiss 3T3 Cells; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D014466:Ultraviolet Rays
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018076:DNA, Complementary; C490666:MAPK8IP1 protein, human; D018808:Transcription Factor AP-1; D017346:Protein Serine-Threonine Kinases; D048055:Mitogen-Activated Protein Kinase 8; D020929:Mitogen-Activated Protein Kinase Kinases; C409022:PDZ-binding kinase