EFFECTS OF IGF-1R NUCLEAR LOCALIZATION IN GLIOBLASTOMA CELLS

MARTIN AYELEN; BERGADA, I; CLEMENT, FLORENCIA; MARIANA GUTIERREZ; VENARA MARCELA; PATRICIA A. PENNISI

Cuzco

Congreso; Congreso Anula de la Sociedad Latinoamericana de Endocrinología Pediátricia; 2018

SLEP

Background: CNS tumors are the most frequent solid tumorsin children. In pediatric gliomas, IGF-1R nuclear localization wassignificantly associated with both high-grade tumors and increasedrisk of death, suggesting that nuclear IGF-1R localizationmay contribute to an aggressive phenotype.Aim: To characterize the impact of IGF-1R overexpression andnuclear localization in glioma cells.Methods: U87Mg glioblastoma cells were transfected withpEGFP-IGF1R to generate stably transfected cells. Lys1025-1100-1120 were targeted by mutagenesis to avoid IGF-1R nuclear translocation.Proliferation assays were carried out during 5 days, andwounding assay for 18 h with/without IGF-1. Protein extracts wereobtained from whole lysates or after subcellular fractionation andprocessed by western blot (WB). Gene expression was quantifiedby rqPCR. IGF-1R/IR inhibitor OSI906 was used at 0.5 uM. Malenude mice were injected for in vivo experiments (1,5e6cells/flank/mice).Results: Stably transfected cells with 5(B4U87) or 50(B2U87)times basal expression of IGF-1R showed higher tumor incidenceand shorter latency time compared to parental cells when injectedin nude mice. In vitro, an increase in pAKT, pERK and pMAPK38was observed after IGF-1 stimulation. Nuclear localization of IGF-1R was verified by IF and WB (8 h IGF-1 stimulation). These effectswere blocked by 1 h preincubation with OSI906. AlthoughCyclinD1 levels were slightly increased in B2U87 and B4U87 cellsin response to 24 h IGF-1 stimulation, proliferation and apoptosiswere not different from parental cells. Wounding assay showed anincreased motility in both B2U87 and B4U87 compared to parentalcells. Moreover, GLUT-1 expression showed a two-fold increaseafter 24 h IGF-1 stimulation that was abrogated by OSI906.Cells expressing GFP-IGF-1R1025x-1100x-1120x showed no IGF-1R nuclear localization and a lower increase in GLUT-1 expressionupon IGF-1 stimulation.Conclusion: IGF-1R overexpression and nuclear localizationmay contribute to an aggressive phenotype of glioblastoma by increasingmotility and metabolism of tumor cells rather than increasingits proliferation.