title: Leukemia inhibitory factor can mediate Ras/Raf/MEK/ERK-induced growth inhibitory signaling in medullary thyroid cancer cells.
abstract: Medullary thyroid carcinoma (MTC) is a multiple endocrine neoplasia type 2 syndrome caused by mutations in extracellular receptor or intracellular kinase domains of the RET proto-oncogene. Activation of the Ras/Raf/MEK/ERK pathway can lead to growth arrest by secreting leukemia inhibitory factor (LIF) in MTC cells harboring a RET receptor domain mutation. Here, we report that Ras/Raf/MEK/ERK can also mediate, via LIF, growth inhibition in MTC cells harboring a RET kinase domain mutation. Ras/Raf/MEK/ERK activation was sufficient to induce growth inhibition and LIF expression in the human MTC line MZ-CRC-1. Presence of LIF-mediated signaling was determined by blocking the activity of culture medium conditioned by Raf-activated cells using anti-LIF neutralizing antibody. In addition, recombinant LIF effectively suppressed cell proliferation via cell cycle arrest in G0/G1 phase. Expression of dominant negative STAT3 abrogated LIF effects, indicating that LIF mediates its signaling through the JAK/STAT3 pathway. These results suggest that growth inhibition and activation of the autocrine/paracrine signaling through LIF/JAK/STAT may be a common response to Ras/Raf activation in different MTC types, and justify further evaluation of LIF as a potential anticancer agent for MTC.
authors.affiliation: Department of Biochemistry, The Medical College of Wisconsin, Milwaukee, 53226, USA.
authors.forename: Dumrongkiet
authors.initials: D
authors.lastname: Arthan
authors.forename: Seung-Keun
authors.initials: SK
authors.lastname: Hong
authors.forename: Jong-In
authors.initials: JI
authors.lastname: Park
mesh_terms: D019898:Autocrine Communication; D018276:Carcinoma, Medullary / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D016923:Cell Death; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D017077:Culture Media, Conditioned / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D053612:Janus Kinases / Q000378:metabolism; D053605:Leukemia Inhibitory Factor / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D009154:Mutation; D019899:Paracrine Communication; D000090063:Proto-Oncogene Mas; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000378:metabolism*; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013964:Thyroid Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D013997:Time Factors; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D017077:Culture Media, Conditioned; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011994:Recombinant Proteins; D050796:STAT3 Transcription Factor; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; D053612:Janus Kinases; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; D018631:ras Proteins