Fig. 4

Isoliquiritigenin (ISL) prolongs survival, delays growth and induces vessel normalization in C6 gliomas with the decreased intratumoral level of 20-HETE and PGE₂. a In the C6 intracranial glioma model, the survival time of the rats (n = 10) injected intraperitoneally with ISL (10 and 20 mg/kg), Sunitinib (80 mg/kg) or vehicle was measured, and 20-HETE and PGE₂ in the tumor tissues from each group were determined at day 12 by LC-MS/MS or ELISA. b In the C6 subcutaneous glioma model, rat C6 glioma cells (5 × 10⁶) were injected subcutaneously into the right flank of Wistar rats. When tumors reached a size of about 100 mm³, the rats (n = 8) received ISL (10 and 20 mg/kg), Sunitinib (80 mg/kg) or vehicle by intraperitoneal injection once daily for a week. Tumor weight was measured, and 20-HETE and PGE₂ were determined by LC-MS/MS or ELISA. The values are presented as the mean ± SEM, ^*P < 0.05, ^**P < 0.01 vs. control, ^#P < 0.05, ^##P < 0.01 vs. sunitinib (80 mg/kg)-treated group. c-h Rat C6 glioma cells (5 × 10⁶) were injected subcutaneously into the right flank of Wistar rats. When tumors reached a size of about 100 mm³, the rats (n = 8) received ISL (10 and 20 mg/kg) or vehicle by intraperitoneal injection once daily for a week. Tumor perfusion at day 0, 2, 4, 6 and 8 was measured using a laser Doppler analyzer. Scale bars, 2 mm (c). The quantitative analysis showed the relative level of tumor perfusion (d). After sacrificing the rats at day 8, hypoxia induced factor (HIF)-1α in the tumor tissues was measured by Western blot (e). Double staining for CD31 (green) and α-SMA (red) in the tumor tissues was shown. Scale bars, 50 μm (f-h). i In the C6 intracranial glioma model, the survival time of the rats (n = 10) injected intraperitoneally with ISL (20 mg/kg), temozolomide (TMZ, 20 mg/kg), ISL (20 mg/kg) plus TMZ (20 mg/kg) or vehicle was measured, and TMZ uptake into tumor tissues was determined at day 12 by high performance liquid chromatography (HPLC). j In another experiment, rat C6 glioma cells (5 × 10⁶) were injected subcutaneously into the right flank of Wistar rats. When tumors reached a size of about 100 mm³, the rats (n = 8) received ISL (20 mg/kg), TMZ (20 mg/kg), ISL (20 mg/kg) plus TMZ (20 mg/kg) or vehicle by intraperitoneal injection once daily for a week. Tumor weight was measured, and TMZ uptake into tumor tissues was determined by HPLC. The values are presented as the mean ± SEM, ^*P < 0.05, ^**P < 0.01 vs. control, ^#P < 0.05, ^##P < 0.01 vs. TMZ (20 mg/kg)-treated group