Evaluation of the cytotoxic and apoptogenic effects of cinnamaldehyde on U87MG cells alone and in combination with doxorubicin

Background and purpose: In the present study, we tried for the first time to examine whether cinnamaldehyde (CA), with herbal nature, can be co-administrated with doxorubicin (DOX, as an anticancer drug) toward U87MG glioblastoma cells to potentiate its cytotoxic effect and overcome or reduce its side effects. Experimental approach: The cytotoxic effect of DOX and CA, either individually or in combination, were evaluated on U87MG cells using the MTT method. The mechanism of action was studied by investigating the mode of cell death using caspase-3 and 9 activations, mitochondrial membrane potential (MMP) as well as sub G1 analysis. The expression of apoptosis- related genes (Bcl-2 and Bax) was also examined. Findings / Results: Cellular toxicity assay revealed that CA and DOX can potentially reduce the viability of U87MG cells with IC50 at 11.6 and 5 μg/mL, respectively. Exposure with the combination of CA and DOX significantly increased cytotoxic effect of DOX on U87MG cells. The results of SUBG1, MMP, and also caspase-3 and -9 activity assays, in association with the results corresponding to the Bax and Bcl-2 gene expressions, altogether revealed that CA can induce apoptosis on U87MG cells. Moreover, apoptogenic effects of DOX were found to be potentiated by CA. Conclusion and implications: The results of this study revealed the promising cytotoxic and apoptogenic role of CA on U87MG cells. Additionally, our findings demonstrated that CA is able to enhance the apoptosis induced by DOX on human glioblastoma cells. Collectively, these data suggested that co-exposure of CA and DOX could be effective for treatment of glioblastoma, but further in vivo and clinical studies are still needed to prove these results.