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Bcl-2 and Bcl-xL in Peroxide-Resistant A549 and U87MG Cells
Journal article   Open access   Peer reviewed

Bcl-2 and Bcl-xL in Peroxide-Resistant A549 and U87MG Cells

Heidi K. Bojes, P. K. Suresh, Edward M. Mills, Douglas R. Spitz, Julia E. Sim and James P. Kehrer
Toxicological sciences, Vol.42(2), pp.109-116
04/1998
DOI: 10.1093/toxsci/42.2.109
PMID: 9579023
url
https://doi.org/10.1093/toxsci/42.2.109View
Published (Version of record) Open Access

Abstract

Overexpression of the bcl-2 and the related bcl-xL protoonco-gene proteins enhance cell survival by inhibiting apoptosis induced by many agents including oxidants. Whether these proteins contribute to survival in oxidant-resistant cells is not known. The current study assessed the expression of bcl-2 and bcl-xL proteins in human glioblastoma U87MG cells and human lung adenocar-cinoma A549 cells selected for resistance to 0, 50, 100, 200, and 400 μM H2O2 by exposure to this oxidant one time each passage for 9 months. When examined 7 to 32 days after cessation of peroxide exposure (times when peroxide resistance was maintained), bcl-2 protein levels were significantly increased in most peroxide-resistant U87MG cells. However, the increase was not dose dependent and was not accompanied by an increase in mRNA levels. A549 cells did not express significant levels of bcl-2 protein, although bcl-2 mRNA was detectable. A549 cells expressed large amounts of bcl-xL and immunohistochemistry demonstrated extensive localization of this protein around the nucleus. However, expression of this protein was not altered in peroxide-resistant lines nor was bcl-2 protein increased to a measurable level. U87MG cells also expressed bcl-xL but it was not altered in peroxide-resistant cells. Although the increased bcl-2 protein in peroxide-resistant U87MG cells may contribute to their oxidant tolerance, the lack of a dose-response relationship, the failure to induce bcl-xL protein, and the absence of any bcl-2 or bcl-xL protein induction in peroxide-resistant A549 cells suggest these genes are not primary factors in oxidant resistance.
A549 cells bcl-2 bcl-xL hydrogen peroxide oxidant toxicity U87MG cells

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