The effect of curcumin in combination with radiation therapy and hyperthermia for a glioblastoma spheroid model

Background: The most common form of human primary brain tumor resistant to treatment is glioblastoma multiforme. For brain tumors, it is essential to optimize the treatment regimen with curcumin as a sensitizing agent and adjunctive to traditional or alternative therapy. This study aimed to determine the combined effects of cell death and apoptosis caused by curcumin before and after radiation with hyperthermia on glioblastoma in a monolayer cell culture and spheroid cell model. Materials and Methods: The spheroid cells were separately or simultaneously treated with the IC50% concentration of curcumin before and after 2 Gy radiation. Hyperthermia was then applied by incubating the cells at 43 degrees C for 1 hr. The survival rate of the cells was measured via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Bax, Bcl-2, and caspase-3 expressions were quantified with real-time PCR (RTPCR). Results: Cell viability significantly decreased in the curcumin (before) with radiation group (CCM+IR) by 51.12%, and in the radiation, curcumin, and hyperthermia group (IR+ CCM+ H) by 31.01%. The expression level of Bax and caspase3 significantly increased in the combination of radiation, curcumin, and hyperthermia group (IR+ CCM+ H) by 3.80 +/- 0.02 and 5.13 +/- 0.12, respectively. The Bcl-2 expression level in the radiation with curcumin and hyperthermia group was 0.41 +/- 0.01, compared to the curcumin before radiation group (0.70 +/- 0.05) and the curcumin after radiation group (0.60 +/- 0.02). Conclusion: Curcumin was more effective on cell death after radiation. It caused a synergistic effect in combination with other adjuvant therapies for glioblastoma spheroid cells.