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Previous issue date: 2012-05-29 === Glioblastoma multiforme (GMB) is the most malignant and common type of all astrocytic tumours. Current standard treatment for GBM patients involves maximum surgical resection of the tumour, followed by radiotherapy and chemotherapy, usually containing the alkylating agent Temozolomide (TMZ). Despite this aggressive combination therapy, the survival rate of GBM patients is still low. This work consisted in investigating the cytotoxic effects of Akt-inhibition by MK-2206 with irradiation (RT) and TMZ on in vitro human malignant glioma. Seven malignant glioma cell lines were cultured and tested for clonogenic survival, invasion inhibition, tumour spheroid growth and proliferation. The Akt-inhibitor MK-2206 and TMZ were added at different time treatments and in varying doses. Cultures were irradiated with single dose and with fractionated γ-irradiation. Cellular modulation of Akt and p-Akt were assessed by Western blot analysis. MK-2206 reduced the levels of phospho- Akt key protein in the PI3Kinase-Akt pathway, decreased cell survival, and inhibited invasion, proliferation and cell growth. The combination of MK-2206 and RT lead to enhanced inhibition of cell proliferation and invasion, which is not observed with RT alone. The radioenhancing effect of MK-2206 was most striking in inhibition of spheroid volume growth by fractionated RT; the radiosensitizing effect of MK-2206 was stronger than that of TMZ. MK-2206 enhanced the in vitro effects of RT and TMZ in terms of decreased cell survival, invasion, proliferation and growth in malignant glioma. Effects could be ascribed to inhibition of PI3K-Akt pathway === O Glioblastoma multiforme (GBM) ? o tipo mais maligno e mais comum de todos tumores astroc?ticos. O tratamento atual para pacientes de GBM envolve m?xima remo??o cir?rgica, seguida de radio e quimioterapia, normalmente com o agente alquilante Temozolamida (TMZ). Apesar da agressividade da terapia combinada, o tempo de sobreviv?ncia dos pacientes ainda ? baixo. Este trabalho procurou investigar os efeitos citot?xicos do inibidor de Akt MK-2206 em combina??o com irradia??o (RT) e TMZ em um painel de c?lulas de gliomas humanos. Sete linhagens de glioma foram cultivadas e testadas em ensaio de sobreviv?ncia clonog?nica, inibi??o de invas?o, e modelos de prolifera??o e crescimento de volume em esfer?ides. O inibidor MK-2206 e TMZ foram adicionados em diferentes tempos de tratamento e diferentes doses. As culturas foram irradiadas com doses ?nicas ou em terapias fracionadas com irradia??o γ. A modula??o celular de Akt e fosfo-Akt foi checada via Western Blot. O composto MK-2206 reduziu a fosforila??o da prote?na chave Akt na via PI3K, diminuindo a sobreviv?ncia celular e inibindo invas?o, prolifera??o e crescimento celular. A combina??o de MK-2206 com RT levou a uma maior inibi??o de invas?o e prolifera??o, o que n?o ? observado somente com a RT. O efeito radiosens?vel de MK-2206 foi ainda maior na inibi??o do volume dos esfer?ides em terapia combinada com RT fracionada, sendo ainda maior do que o efeito combinado com TMZ. MK-2206 aumentou os efeitos in vitro de RT e TMZ em termos de redu??o de sobreviv?ncia celular, invas?o, prolifera??o e crescimento celular em gliomas malignos. Os efeitos podem ser atribu?dos a inibi??o da via PI3KAkt
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