title: ERK couples chronic survival of NK cells to constitutively activated Ras in lymphoproliferative disease of granular lymphocytes (LDGL).
abstract: Chronic NK lymphoproliferative disease of large granular lymphocytes (LDGL) is characterized by the expansion of activated CD3-, CD16+ or CD56+ lymphocytes. The mechanism of survival of NK cells from LDGL patients is unknown but may be related to antigenic stimulation. There is currently no standard effective therapy for LDGL, and the disease is characteristically resistant to standard forms of chemotherapy. We found evidence of constitutive activation of extracellular-regulated kinase (ERK) in NK cells from 13/13 patients with NK-LDGL (one patient with aggressive and 12 patients with chronic disease). Ablation of ERK activity by inhibitors or a dominant-negative form of MEK, the upstream activator of ERK, reduced the survival of patient NK cells. Ras was also constitutively active in patient NK cells, and exposure of cells to the Ras inhibitor FTI2153 or to dominant-negative-Ras resulted not only in ERK inhibition but also in enhanced apoptosis in both the presence and absence of anti-Fas. Therefore, we conclude that a constitutively active Ras/MEK/ERK pathway contributes to the accumulation of NK cells in patients with NK-LDGL. These findings suggest that strategies to inhibit this signaling pathway may be useful for the treatment of the NK type of LDGL.
authors.affiliation: Hematologic Malignancies, Programs from the Department of Interdisciplinary Oncology, H Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, FL 33612, USA. burnetpk@moffitt.usf.edu
authors.forename: Pearlie K
authors.initials: PK
authors.lastname: Epling-Burnette
authors.forename: Fanqi
authors.initials: F
authors.lastname: Bai
authors.forename: Sheng
authors.initials: S
authors.lastname: Wei
authors.forename: Pratima
authors.initials: P
authors.lastname: Chaurasia
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Painter
authors.forename: Nancy
authors.initials: N
authors.lastname: Olashaw
authors.forename: Andrew
authors.initials: A
authors.lastname: Hamilton
authors.forename: Said
authors.initials: S
authors.lastname: Sebti
authors.forename: Julie Y
authors.initials: JY
authors.lastname: Djeu
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Loughran
mesh_terms: D015153:Blotting, Western; D002470:Cell Survival; D006801:Humans; D016130:Immunophenotyping; D007694:Killer Cells, Natural / Q000166:cytology*; D008214:Lymphocytes / Q000166:cytology*; D008232:Lymphoproliferative Disorders / Q000276:immunology / Q000473:pathology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D020928:Mitogen-Activated Protein Kinases