Abstract. Curcumin has been verified as an anti-cancer compound via multiple molecular targets. Its effective mechanisms include cell cycle arrest, inducing apoptosis, suppressing oncogenes, and enhancing tumor suppressor genes. The resistance of cells to chemotherapy, however, derives from the variable genetic aberration of cancer cells. Consequently, the core signaling pathways of glioblastoma have been explored to evaluate the efficacy of curcumin in proceeding through mutated genes in those pathways. In this study, the efficacy of curcumin was investigated in DBTRG cells. The cytotoxic ability was detected with MTT assay, and the influence of the cell cycle was checked with flow cytometry. The influence of the core signaling pathways was evaluated by Western blotting through the predominantly mutated proteins which included p53, p21, and cdc2 in the p53 pathway, CDKN2A/p16 and RB in the RB pathway, and EGFR, mTOR, Ras, PTEN, and Akt in the RTK-Ras-PI3K pathway. In addition, the apoptotic effect was determined by apoptosis-associated proteins Bcl-2, Bax, and caspase 3. Curcumin exhibits superior cytotoxicity on glioblastoma in a dose-and time-dependent manner in the MTT assay. In the core signaling pathways of glioblastoma, curcumin either significantly influences the p53 pathway by enhancing p53 and p21 and suppressing cdc2 or significantly inhibits the RB pathway by enhancing CDKN2A/p16 and suppressing phosphorylated RB. In the apoptotic pathway, the Bax and caspase 3 are significantly suppressed by curcumin and the Giemsa stain elucidates apoptotic features of DBTRG cells as well. In conclusion, curcumin appears to be an effective antiglioblastoma drug through inhibition of the two core signaling pathways and promotion of the apoptotic pathway.

Microglia has been found to diversify its function by cancerous cells or in a cancerous environment, thereby contributing to cancer growth and metastasis. Its immuno-activity, however, can be modulated by interleukin-12. So a strategy was designed using AAV2 carrying IL-12 to activate microglia then to eliminate cancerous cells. The transduction efficacy of AAV was evaluated with AAV2 encoding GFP and IL-12 on cancerous and CNS cells. The bioactivity of microglia modulated by IL-12 was examined and death receptors 4 and 5 were detected on cancerous cells. The effects of IL-12 and AAV2/IL-12 on microglial cytoxoxicity were evaluated too. The results demonstrated human cell line DBTRG, surgical specimen of GBM, and rat astrocyte expressed GFP quite well. Tremendous IL-12 secretion was detected in DBTRG, RG2, and astrocyte after transfection of AAV2/IL-12. TRAIL releasing and phagocytotic activity of microglia were significant, increasing (p<0.05) after the stimulation of IL-12. DR4 and DR5 were expressed in all of the examined GBM cells. MTT assay of microglial cytotoxicity elicited significant increase (p<0.05) when the IL-12 protein or RG2-secreting IL-12 could have contact with microglial cells. Conclusively, AAV2 is an effective vector in transferring therapeutic genes such as IL-12 to induce or enhance microglial anti-cancer activity.