title: Inhibition of MAP-kinase cascade normalizes the proliferation rate of fibroblasts from patients with Type 1 diabetes and nephropathy.
abstract: Faster proliferation rate characterizes human skin fibroblasts from patients with Type 1 diabetes and nephropathy (DN), but the reason of this phenomenon is still unknown. Growth factors control cell proliferation through an intracellular mitogen-activated protein (MAP) kinase cascade. We have examined the effect of the inhibition of MAP kinase/ERK kinase (MEK), a key point of the MAP kinase cascade, on the proliferation rate of fibroblasts from 40 patients with Type 1 diabetes (20 with and 20 without DN) and from 10 nondiabetic participants. Proliferation rate was measured by cell count in the presence or absence of 30 mumol/l of the MEK inhibitor PD 098059. In normal cultural conditions, proliferation rate was faster in fibroblasts from patients with (0.175+/-0.009x10(5) cells day-1, mean+/-S.E.M.) than without DN (0.110+/-0.009) and in nondiabetic participants (0.094+/-0.008; ANOVA P<.0001). The inhibition of MEK induced a stronger reduction of proliferation rate in fibroblasts from patients with (0.079+/-0.006x10(5) cells day(-1); 55% of reduction) than without DN (0.068+/-0.006; 38% of reduction) and in nondiabetic participants (0.064+/-0.006; 32% of reduction), and differences among groups were lost. In parallel, PD 098059 induced a greater reduction of MEK-dependent phosphorylation in lysates of fibroblasts from patients with (73%) than without (40%) DN. In conclusion, the inhibition of MEK normalizes the proliferation rate of fibroblasts from patients with DN, suggesting that the MAP kinase cascade could be involved in this cellular dysfunction.
authors.affiliation: Renal Pathophysiology Laboratory, Division of Medicine, San Raffaele Scientific Institute, I-20132 Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Maestroni
authors.forename: Francesca
authors.initials: F
authors.lastname: Tentori
authors.forename: Giancarla
authors.initials: G
authors.lastname: Meregalli
authors.forename: Daniela
authors.initials: D
authors.lastname: Gabellini
authors.forename: Veronica
authors.initials: V
authors.lastname: Asnaghi
authors.forename: Dora
authors.initials: D
authors.lastname: Ruggieri
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Zerbini
mesh_terms: D000328:Adult; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism; D003928:Diabetic Nephropathies / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one