Immediate early gene IEX‐1 induces astrocytic differentiation of U87‐MG human glioma cells

Abstract

The immediate early response gene IEX-1 is involved in the regulation of apoptosis and cell growth. In order to increase the apoptotic sensitivity to chemotherapeutic drugs and g-ray, we attempted to establish U87-MG human glioma cell line expressing IEX-1. Unexpectedly, however, transfection of IEX-1 into U87-MG glioma cells resulted in morphological changes to astrocytic phenotype and increase in glial differentiation marker proteins, S-100 and glial fibrillary acidic protein (GFAP). Glial cell differentiation was used to examine in rat C6 glioma cell line, since this cell line express astrocytic phenotypes by increase in intracellular cAMP concentration. Stimulation of human U87-MG glioma cells by membrane-permeable dibutyryl cAMP (dbcAMP) not only elicited their morphological changes but also induced expression of IEX-1 as well as S-100 and GFAP. H89, an inhibitor of protein kinase A (PKA), blocked dbcAMP-induced morphological changes of U87-MG cells and expression of IEX-1. In contrast, morphological changes and expression of S-100 and GFAP induced by IEX-1 were not affected by H89. Morphological changes induced by dbcAMP were totally abolished by functional disruption of IEX-1 expression by anti-sense RNA. These results indicate that IEX-1 plays an important role in astrocytic differentiation of human glioma cells and that IEX-1 functions at downstream of PKA.

Overexpression of immediate early gene X‐1 (IEX‐1) enhances γ‐radiation‐induced apoptosis of human glioma cell line, U87‐MG

“…There is little information regarding the role of IEX‐1 in the nervous system. The possible role of IEX‐1 in cells of neuronal origin have been reported 21 . Our present study first demonstrates the involvement of IEX‐1 in the radiation‐induced apoptosis of glioma cells.…”

“…The possible role of IEX-1 in cells of neuronal origin have been reported. 21 Our present study first demonstrates the involvement of IEX-1 in the radiation-induced apoptosis of glioma cells. The following were clarified in our present study: (i) g-radiation lead to cell death and at least a part of the cell death was apoptosis ( Fig.…”

Oligodendroglia metabolically support axons and contribute to neurodegeneration

“…44,45 Lactate uptake assay was completedas described previously 46 with only small modifications. In brief, cells were incubated with 0.5 μCi/mL L-[1- 14 C] lactic acid (Perkin-Elmer, Boston MA, USA) in HEPES-buffered, Earl’s balanced salt solution (HEBSS) buffer, pH 6.0, containing150mM NaCl, 5mM KCl, 1mM KH 2 PO 4 , 0.2mM CaCl 2 .2H 2 O, 3.3mM MOPS, 10mM HEPES, 1mM MgSO 4 .7H 2 O.…”

AKT plays a pivotal role in the acquisition of resistance to 5-fluorouracil in human squamous carcinoma cells

“…Total cellular protein extracts were used for Western blot analysis (9,10). For the preparation of cell extracts, cells were sonicated in RIPA buffer (25 mM HEPES pH 7.4, 1% Triton-X, 150 mM NaCl, 0.1% sodium dodecylsulfate, 0.5% sodium deoxychlolate, 10 mM EDTA, 1 mM phenylmethylsulfonyl fluoride and 10 μg/ml leupeptin) containing phosphatase inhibitors: 1 mM sodium orthovanadate, 10 mM sodium fluoride and 0.1 mM sodium molybdate.…”