Overexpression of bax in human glioma cell lines

Object. Cells that lose their ability to undergo apoptosis may promote the development of neoplasms and result in resistance to clinical treatment wit h DNA-damaging modalities such as radio- and chemotherapy. Four established human glioma cell lines that are resistant to apoptosis were transfected w ith the proapoptotic gene bar and assessed for their sensitivity to a proap optotic stimulus. Methods. Two cell lines had a wild-type p53 genotype (U87 and D247MG) and t wo had mutant p53 genotypes (U138 and U373). Constitutive overexpression of murine bax was achieved in U138 and U373 only, which resulted in an increa sed sensitivity of these lines to the apoptosis-inducing effect of cytosine arabinoside (ara-C). Multiple attempts to produce constitutive overexpress ion of bax in U87 and D247MG cells resulted in spontaneous, near-complete c ell loss. Vector-only control transfections were successful in all four cel l lines. Inducible overexpression of bax was achieved in the U87 cells and elevated levels of BAX were observed as early as 6 hours after gene inducti on. This overexpression of BAX resulted in the spontaneous induction of apo ptosis in these cells. Conclusions. Overexpression of BAX in four human glioma cell lines resulted in increased sensitivity to apoptosis. In the two lines that had a wild-ty pe p53 genotype, overexpression of BAX produced spontaneous apoptosis. In c ontrast, the lines that had mutant, nonfunctional P53 did not undergo spont aneous apoptosis, but they were rendered more sensitive to the apoptosis-in ducing effect of ara-C. Modulation of BAX expression may be a useful therap eutic modality for gliomas, regardless of p53 genotype.