title: Insulin-activated, K+-channel-sensitive Akt pathway is primary mediator of ML-1 cell proliferation.
abstract: Voltage-gated K(+) channel activities are involved in regulating growth factor-stimulated cell proliferation in a variety of cell types. Here we report that suppression of a voltage-gated K(+) channel with 4-aminopyridine (4-AP), barium, and tetraethylammonium inhibited both EGF- and insulin-stimulated myeloblastic leukemia ML-1 cell proliferation in a concentration-dependent manner. Both MAPK/ERK and Akt pathways are known to mediate cell proliferative signals of a variety of growth factors including insulin. In serum-starved ML-1 cells, insulin rapidly stimulated phosphorylation of ERK1/2 and Akt, and the phosphorylation levels peaked approximately 30 min after treatment. Pretreatment of ML-1 cells with 4-AP potently and dose-dependently prevented phosphorylation of ERK1/2 and Akt. However, insulin-induced activation of the Akt pathway also played a role in promoting ML-1 cell proliferation. Flow cytometry analysis revealed that although ML-1 cells were primarily arrested at G(1) phase by serum starvation for 36 h, they reentered the cell cycle after treatment with serum or insulin for 24 h. However, concomitant 4-AP treatment was able to attenuate cell cycle progression in synchronized ML-1 cells stimulated with growth factors. Our results strongly suggest that a 4-AP-sensitive K(+) channel activity plays an important role in controlling proliferation of ML-1 cells by affecting the activation of multiple signal transduction processes induced by insulin.
authors.affiliation: Health Science Center, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai Second Medical University, Shanghai, China.
authors.forename: Taylor B
authors.initials: TB
authors.lastname: Guo
authors.forename: Jiawei
authors.initials: J
authors.lastname: Lu
authors.forename: Tie
authors.initials: T
authors.lastname: Li
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Lu
authors.forename: Guotong
authors.initials: G
authors.lastname: Xu
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.forename: Luo
authors.initials: L
authors.lastname: Lu
authors.forename: Wei
authors.initials: W
authors.lastname: Dai
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D010766:Phosphorylation; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D019789:Tetraethylammonium / Q000494:pharmacology
chemical_list: D007328:Insulin; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D011518:Proto-Oncogene Proteins; D001464:Barium; D004815:Epidermal Growth Factor; D019789:Tetraethylammonium; D015761:4-Aminopyridine; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020929:Mitogen-Activated Protein Kinase Kinases