Additive anticancer effects of chrysin and low dose cisplatin in human malignant glioma cell (U87) proliferation and evaluation of the mechanistic pathway.

Purpose: To evaluate the anticancer effect of chrysin and its additive combination with low-dose cisplatin in human glioma (U87) cancer cells and to study its underlying mechanism. Methods: Inverted phase and fluorescence microscopic studies were done to demonstrate the effect of chrysin and its combination with cisplatin on cellular morphology and apoptosis. Annexin V-FITC assay was used to quantify the extent of apoptosis in chrysin and chrysin+cisplatin treated cells. Flow cytometry using propidium iodide (PI) as a staining agent was used to study the effect of chrysin and its combination with cisplatin on cell cycle phase distribution. Results: The results showed chrysin brought about a potent and dose-dependent antiproliferative effect in human glioma cancer cells. However, the combination of chrysin with low dose cisplatin led to a much higher growth inhibitory effects indicating an additive effect between the two compounds. The combined effect of chrysin and cisplatin also gave rise to a greater apoptosis induction as well as cell cycle arrest in comparison to the treatment by chrysin or cisplatin alone. Fluorescence microscopy as well as inverted phase contrast microscopy also revealed that the combination of chrysin plus cisplatin resulted in greater apoptosis induction as well as cell morphology alterations. Combination treatment of chrysin and cisplatin resulted in greater percentage of cells in early as well as in late apoptotic stages. The combination effect was also seen in mitochondrial membrane potential loss. Conclusion: Chrysin additively potentiates the antiproliferative, cell cycle arrest and apoptotic activity of cisplatin in human glioma cancer (U87) cells.