Radiosensitization Effects of a Zataria multiflora Extract on Human Glioblastoma Cells

Although radiotherapy is one of the most effective strategies in the treatment of cancers, it is associated with short and long term side effects on normal tissues. Zataria multiflora Boiss (Laminacea) (ZM) has several biological properties such as antioxidant and anti-inflammation activities.Here we investigated cell killing effects of a hydroalcoholic Zataria multiflora extract on cell death induced by ionizing radiation in a human glioblastoma cell line (A172) and human non-malignant fibroblasts (HFFF2) in vitro.

A172 and HFFF2 cells were treated with a hydroalcoholic extract of dried aerial parts of Zataria multiflora at different concentrations (25, 50, 100, 150 and 200 μg/ml) and then exposed to ionizing radiation (IR). Cell proliferation and DNA fragmentation were evaluated. Thymol content in the extract was analyzed and quantified by HPLC methods.

A172 cell proliferation was significantly inhibited by ZM. The percentage cell survival was 91.8 ± 8.57 for cells treated with 200 μg/ml of ZM extract alone while it was 76.0 ± 4.27 and 66.2 ± 8.42 for cells treated with ZM and exposed to IR at doses of 3 Gy and 6Gy, respectively. Radiation-induced apoptosis in A172 cells was significantly increased following treatment with ZM at doses of 200 μg/ml. ZM extract did not exhibit any enhanced cell killing effects and apoptosis caused by IR on HFFF2 cells.

These data show selective radiosensitization effects of ZM in A172 cells apparently due to increased radiation-induced apoptosis.