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Sustaining proliferative signaling
[Role of suppressor encoprotein PTEN in IGF-1 induced activation of ERK in endometrial carcinoma cells].
BACKGROUND & OBJECTIVES:
The machanism of signal transduction of insulin-like growth factor (IGF-1) in endometrial carcinoma is still unknow. The objective of this paper was to study extracellular signal-regulated kinase(ERK) activation in endometrial carcinoma cell line Ishikawa under the stimulation of IGF-1, and to elucidate the role of suppressor encoprotein phosphatase and tensin homologue(PTEN) in activation of ERK.
METHODS:
Retrovirus vector of PTEN and PTEN (G129E) was constructed. Ishikawa was transfected in vitro. Expressionstable cell line was screened by G418. Western blot was applied to examine PTEN expression in Ishikawa cells after transfection. Optimal concentration and time of IGF-1 and 17-beta-estrodial which activated ERK in Ishikawa-PTEN and Ishikawa-PTEN(G129E) cells were detected. Western blot was applied to examine ERK activation under the stimulation of 17-beta-estrodial in NIH3T3 fibroblasts after transient transfection of pCXN2hER alpha and pCXN2hER beta.
RESULTS:
IGF-1 activated ERK cascades(mainly ERK2) in Ishikawa cells. There was no obvious difference in ERK activation among different doses of IGF-1 (20, 40, and 80 micrograms/L), But the maximal activations of ERK2 took place at 5 min after stimulation with IGF-1. The activation of ERK2 was inhibited obviously by PTEN at 30 min, 2 h, and 24 h. There was no obvious difference in ERK activation between Ishikawa-PTEN(G129E) and Ishikawa-EGFP. 17-beta-estrodial activated ERK cascades (mainly ERK2) in Ishikawa cells. The activation of ERK was increased with increasing of concentration. The maximal activations of ERK2 took place at 5 min after stimulation with 17-beta-estrodial. The activation of ERK2 was inhibited obviously by PTEN, not by PTEN(G129E). 17-beta-estrodial activated ERKs cascades in NIH3T3 fibroblasts after transient transduction of pCXN2h-ER alpha.
CONCLUSIONS:
17-beta-estrodial and IGF-1 activated ERK cascades in Ishikawa cells. Lipid phosphatase of PTEN had an inhibitory role in the activation of ERK under the stimulation of 17-beta-estrodial and IGF-1.