Stimulation of phosphoinositol turnover and protein kinase C activation by granulocyte-macrophage colony-stimulating factor in HL-60 cells

Abstract Phosphoinositol turnover, diacylglycerol generation, protein kinase C (PK-C) activity, and intracellular cyclic nucleotides were studied in an established human leukemia cell line, HL-60, in response to one of the hematopoietic cytokines, granulocyte-macrophage colony-stimulating factor (GM-CSF). Continuous exposure of HL-60 cells to GM-CSF induced the cell differentiation that was evaluated by the nitroblue tetrazolium (NBT) reducing activity. GM-CSF also exhibited a proliferative effect on HL-60 cells. GM-CSF at 1 nmol/L, an optimal concentration for cell growth and cell differentiation, induced significant changes in the intracellular inositoltriphosphate (IP3). Diacylglycerol generation was also stimulated by GM-CSF treatment. GM- CSF increased the membrane PK-C activity by 10-fold of the control, whereas no measurable change in cyclic nucleotides was observed. These data indicated that phosphoinositol turnover and the activation of PK-C were included in the GM-CSF signal transducing pathway in HL-60 cell. Phosphoinositol response leading to PK-C activation may act as a trigger signal of cell differentiation by GM-CSF.</jats:p

Stimulation of phosphoinositol turnover and protein kinase C activation by granulocyte-macrophage colony-stimulating factor in HL-60 cells

Phosphoinositol turnover, diacylglycerol generation, protein kinase C (PK-C) activity, and intracellular cyclic nucleotides were studied in an established human leukemia cell line, HL-60, in response to one of the hematopoietic cytokines, granulocyte-macrophage colony-stimulating factor (GM-CSF). Continuous exposure of HL-60 cells to GM-CSF induced the cell differentiation that was evaluated by the nitroblue tetrazolium (NBT) reducing activity. GM-CSF also exhibited a proliferative effect on HL-60 cells. GM-CSF at 1 nmol/L, an optimal concentration for cell growth and cell differentiation, induced significant changes in the intracellular inositoltriphosphate (IP3). Diacylglycerol generation was also stimulated by GM-CSF treatment. GM- CSF increased the membrane PK-C activity by 10-fold of the control, whereas no measurable change in cyclic nucleotides was observed. These data indicated that phosphoinositol turnover and the activation of PK-C were included in the GM-CSF signal transducing pathway in HL-60 cell. Phosphoinositol response leading to PK-C activation may act as a trigger signal of cell differentiation by GM-CSF.</jats:p

Follow-Up Imaging of Inflammatory Myofibroblastic Tumor of the Uterus and Its Spontaneous Regression

Inflammatory myofibroblastic tumor (IMT) is an aggressive benign mass that may arise from various tissues and organs with a great variability of histological and clinical appearances. Due to variable and nonspecific imaging findings, diagnosis of IMT is not obtained before surgery. The aim of this paper is to present CT and MRI findings during four-year follow-up of complete, spontaneous regression of IMT of the uterus. The diagnosis was made by histology and immunohistochemistry analysis of the open excisional biopsy specimen. At that time, the organ of origin was not specified. After analysis of the follow-up imaging findings and the mode of tumor regression, the uterus was proclaimed as the probable site of origin. IMT of the uterus is extremely rare and has been reported in ten cases up to now. The gradual, complete regression of uterine IMT documented by CT and MRI may contribute to understanding of its nature