FIGURE 2.

Dipotassium glycyrrhizinate (DPG) increases apoptosis and inhibits proliferation in glioblastoma cell lines. U87MG (A) and T98G (B) cells were incubated with 18 mM and 24 mM of DPG, respectively, for 48 and 72 h. T98G was also treated using 24 mM DPG for 96 h. The genomic DNA was isolated and analyzed on 1.5% agarose gel with ethidium bromide staining. M: DNA marker 100 base pairs; C: untreated control cells. Results are representative of one of three similar experiments performed. U87MG (C) and T98G (D) cells were treated with DPG (18 mM for 72 h and 24 mM for 96 h of DPG, respectively). After DPG incubation TUNEL assay was done using in situ cell death detection kit as per the manufacturer’s protocol and the quantitative estimation of TUNEL cells after DPG exposure was measured using ImageJ. Each experiment was repeated three times. The results show a significant increase in the number of apoptotic U87MG cells (P = 0.03) after DPG treatments as compared to the untreated control cells. T98G (P = 0.19) cell also presents an increase in the apoptotic cell number. (E) Cleaved caspase-3 was measured by Western blotting analysis after treatment with 18 mM (U87MG) and 24 mM (T98G). The induction of the cleaved form of caspase-3 (11 kDa) protein increased 48 h after treatment. DPG increased cleaved caspase-3, indicating that apoptosis required caspase activation. (F) Also, DPG significantly increases PARP-1 expression in U87MG (P = 0.05) and T98G (P = 0.01) cells when compared with untreated cells. DPG inhibits the proliferating rate of U87MG (G) and T98G (H) cell lines in a time-dependent trend, in comparison with untreated control cells. Data represent means and standard deviations of a representative experiment performed in triplicate. Statistics were performed in a two-tailed t-test with P < 0.01.