DRES-07. TMZ-LEV- IFN COCKTAIL REGIMEN SIGNIFICANTLY INHIBITED THE GROWTH OF GLIOMA IN VIVO

Abstract

Abstract OBJECTIVE Temozolomide (TMZ), is the first line chemotherapeutic drug for glioma. Previous studies have suggested that interferon (IFN) and levetiracetam (LEV) could respectively reverse the resistance of TMZ by down-regulating MGMT expression. This study, we aim to investigate the therapeutic effect of a cocktail chemotherapy regimen combining TMZ, LEV, IFN in vivo. METHODS Glioma cell lines U251 and SKMG-4 (MGMT protein expression positive), U138 and GSC-1(MGMT protein expression negative) were used for producing xenograft tumors. The xenograft tumors were established by subcutaneously injecting 1×106 glioma cells into female BALB/C nude mice and divided into 5 treatment groups: Control, TMZ, TMZ+IFN, TMZ+LEV, TMZ+LEV+IFN. The treatment with TMZ (50 mg/kg, i.p.), IFN (2×105 IU, s.c.), LEV (150 mg/kg, i.p.) once a day for five consecutive days and xenograft tumors were measured every two days. RESULTS We identified that U138, U251, SKMG-4 tumor growth among TMZ, TMZ+IFN, TMZ+LEV, TMZ+LEV+IFN were all significantly inhibited (P< 0.05), compared with the control. As for U251 and SKMG-4, tumor killing effect of all 4 treatment groups were not different (P > 0.05). In the treatment of mice bearing U138 glioma, the tumor weight of TMZ+LEV+IFN (0.2688±0.1169 g) group was the lowest and significantly lower than that of TMZ+LEV (0.6574±0.08174g, P=0.0261), TMZ+IFN(0.6108±0.07317 g, P=0.0381), and TMZ (0.9054±0.07154 g, P=0.0017) group. Glioma stem cells GSC-1 was highly resistant to TMZ, tumor volume of TMZ group was not different from control group (P >0.05). While compared with TMZ (1.993±0.1274 g) group, in TMZ+IFN (1.506±0.1223g, P=0.0203), TMZ+LEV (1.178±0.1807g, P=0.0042), and TMZ+LEV+IFN (1.049±0.2171 g, P=0.0038) groups, GSC-1 tumor growth were significantly inhibited(P< 0.05). CONCLUSION Our data demonstrate that both IFN and LEV can sensitize TMZ effect on glioma in vivo, even for MGMT(+) tumors, and TMZ-LEV-IFN cocktail regimen seems the best. Key words: glioma, TMZ, LEV, IFN