TR-02: INHIBITION OF AKT SIGNALING AND TUMOR GROWTH BY SUPERCRITICAL CO₂ EXTRACT OF MANGO GINGER (CURCUMA AMADA ROXB.) IN HUMAN GLIOBLASTOMA CELL LINE IN VITRO AND IN NUDE MICE XENOGRAFTS

Mango ginger (Curcuma amada Roxb.), a tropical medicinal plant and spice from Asia, has not been well-investigated for its anticancer properties unlike turmeric (Curcuma longa L.) or the active ingredient curcumin. The inhibitory effect of supercritical CO₂ extract of mango ginger (CA) on AKT signaling was investigated in U-87MG glioblastoma cells. CA was highly cytotoxic to glioblastoma cell line (IC₅₀ = 4.92 ± 0.81 µg/ml) compared to mHypoE-N1 normal mouse hypothalamus cell line (IC₅₀ = 40.57 ± 0.06 µg/ml). When CA was combined with irinotecan (IR), temozolomide or vincristine, CA showed synergistic cytotoxicity with combination index values of <1 in glioblastoma cells. CA inhibits AKT and AMPKα phosphorylation significantly in a dose-dependent manner. The cell migration, which is necessary for invasion and metastasis, was also inhibited by CA treatment with about 43% inhibition at 20 µg/ml concentration. Analysis of mRNA and protein expression of genes showed that CA modulates expression of genes associated with apoptosis (Bax, Bcl-2, Bcl-X, BNIP3, caspase-3, mutant p53, and p21), cell proliferation (Ki67) and angiogenesis (VEGF). Additionally, HSP90 and AMPKα which interact with the AKT signaling pathway were down regulated by CA treatment. Analysis of tumor growth inhibition in nude mice xenografts transplanted with U-87MG glioblastoma cells showed that CA treatment has reduced tumor growth rate by 40.2%, IR by 23.7% and CA + IR by 99.5%. Both CA and CA + IR treated xenografts showed better survival rate than IR and control (saline) groups (*p < 0.0328). These results indicated the molecular targets underlying the anticancer effect of CA in human glioblastoma cells and the potential use of CA as an adjuvant for therapeutic management of glioblastoma.