DDDR-16. CURCUMIN ANALOGS EXHIBIT ANTI-TUMOR ACTIVITY AGAINST GLIOBLASTOMA AT LOWER CONCENTRATIONS THAN CURCUMIN

Abstract PURPOSE Glioblastoma (GBM) has a high risk of recurrence and a poor prognosis due to the difficulty of surgical resection and resistance to the standard treatment, temozolomide. Therefore, the development of new therapeutic agents against GBM is required. This study investigated the anti-tumor activity of the curcumin (Cur) analogs Compound A (ComA) and B (ComB) against GBM. METHODS AND RESULTS To evaluate anti-tumor activity against GBM, we performed a MTT assay. The human glioblastoma cell lines U87-MG and U251 were pre-treated with Cur, ComA, or ComB, then cell viability was examined using a cell counting kit, and IC50 values were calculated. The IC50 values for U87-MG were: Cur, 9.78 µM; ComA, 2.42 µM; and ComB, 1.28 µM. Those for U251 were: Cur, 9.50 µM; ComA, 2.27 µM; ComB, 0.64 µM. To examine the effects of ComA and ComB on normal cells, the same MTT assay was performed on primary cultured astrocytes from neonatal rats. Neither ComA nor ComB resulted in reduced cell viability in astrocytes at concentrations that had an anti-tumor effect on GBM cells (ComA, 3 µM; ComB, 1.5 µM). Next, a cell cycle analysis was performed with PI staining and an apoptosis assay with Annexin V/PI staining using flow cytometry. qPCR was performed to examine the mRNA expression levels of the cell cycle-related proteins CDK1 and CyclinB1. Both ComA and ComB, at lower concentrations than Cur, induced 1) G2/M phase arrest due to a decrease in the mRNA expression levels of CDK1 and CyclinB1 and 2) apoptosis. DISCUSSION These results suggest that both ComA and ComB, at lower concentrations than Cur, have an anti-tumor effect without affecting normal cells by inducing cell cycle arrest and apoptosis against GBM. Further detailed analysis and in vivo studies are expected to lead to the development of novel therapeutic agents for GBM.