Growth inhibition of human malignant glioma cells induced by the PI3-K-specific inhibitor.
OBJECTIVE
The phosphatase and tensin homolog deleted from chromosome 10 (PTEN) functions as a tumor suppressor by negatively regulating the growth/survival signals of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway. The PI3-K/Akt pathway in PTEN-deficient tumors may be one of the key targets for anticancer therapy. The authors examined the effects of the PI3-K inhibitor 2-(4-morpholinyl)-8-phenylchromone (LY294002) on human malignant glioma cells, and compared these effects on PTEN-deficient cells with those on PTEN-wild-type (PTEN-wt) cells.


METHODS
Using human malignant glioma cell lines, including the PTEN-deficient cells A172 and U87MG and the PTEN-wt cells LN18 and LN229, the effects of LY294002 on cell growth, apoptosis, and chemotherapeutic agent-induced cytotoxicity were evaluated. The LY294002 inhibited the growth of U87MG cells associated with reduced phosphatidylinositol 3,4,5,-trisphosphate and phosphorylated Akt, and also induced growth inhibition in three other cell lines. Although LY294002 caused apoptosis in all four cell lines, apoptosis seemed to contribute to only a small portion of growth inhibition induced by LY294002. There was no link between the status of PTEN and the median inhibitory concentration values for LY294002 or between the gene status and the extent of LY294002-induced apoptosis. The LY294002 significantly augmented the cytotoxicity induced by etoposide in PTEN-deficient cells, but not in PTEN-wt cells. Enhancement of 1,3-bis(2-chloroethyl)-1-nitrosourea- and cisplatin-induced cytotoxicity by LY294002 was not linked to the status of PTEN. No marked difference in the amounts of phosphorylated Akt was found between PTEN-deficient and PTEN-wt cells.


CONCLUSIONS
The findings show that PI3-K is a possible target for therapy in patients with gliomas, and PI3-K inhibitors in combination with chemotherapeutic agents could be potent therapeutic modalities for patients with malignant gliomas.
Shingu
Takashi
T
Department of Biochemistry and Neurosurgery, Shimane Medical University, Izumo, Japan. nogeka@shimane-med.ac.jp
Yamada
Kazuo
K
Hara
Nobumasa
N
Moritake
Kouzo
K
Osago
Harumi
H
Terashima
Masaharu
M
Uemura
Takeshi
T
Yamasaki
Toshiki
T
Tsuchiya
Mikako
M
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects* / Q000502:physiology*; D002867:Chromones / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005910:Glioma / Q000503:physiopathology*; D006131:Growth Inhibitors / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D009025:Morpholines / Q000494:pharmacology*; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000172:deficiency / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000494:pharmacology*
D002867:Chromones; D004791:Enzyme Inhibitors; D006131:Growth Inhibitors; D009025:Morpholines; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human