Fig. 2.

Chronic hypoxia-induces treatment resistance in MB and glioblastoma cells. Cell viability was determined using an MTS assay, with absorbance normalised to untreated control. Two MB and one glioblastoma cell lines were pre-cultured in normoxia (21% O₂) or hypoxia (1% O₂) for the indicated time points prior to etoposide, cisplatin or X-ray irradiation treatment. Cells were maintained in 1% O₂ during etoposide [20–100 μM] and cisplatin [1–50 μg/ml] treatment. (a) D283-MED cells treated with etoposide (b) MEB-Med8A treated with etoposide (c) U87MG cells treated with etoposide. (d) D283-MED treated with cisplatin (1–5 μg/ml). (e) MEB-Med8A treated with cisplatin (1–5 μg/ml) (f) U87MG treated with cisplatin (30–50 μg/ml) (g) X-ray irradiation treatment was conducted in 21% O₂ with doses of 30 Gy (D283-MED), 50 Gy (MEB-Med8A) and 2 × 80 Gy dose (U87MG), with 48 h incubation post-treatment. The different doses is to account for different cell sensitivity to irradiation. Data are shown as the mean ± S.E.M of at least 3 independent experiments. A student t-test was performed where (*) indicates statistical significance with p < 0.05