We have examined the relative roles of the two major phospholipid products of PI3K activity, phosphatidylinositol 3,4-biphosphate [PtdIns(3,4)P2] and phosphatidylinositol 3,4,5-triphosphate [PtdIns(3,4,5)P3], in the regulation of PKB activity in glioblastoma cells containing high levels of both of these lipids due to defective PTEN expression.
These results suggest that genetic alterations of class IA PI3K subunit genes can occasionally play a role in human glioblastoma by activating the PI3K-AKT signaling pathway independently of PTEN mutation.
Inhibition of PI3K in U87MG glioblastoma cells, which have activated PI3K/Akt activity secondary to phosphatase and tensin homologue deleted on chromosome 10 (PTEN) mutation, with LY294002 blunted the induction of HIF-1alpha protein and its targets vascular endothelial growth factor and glut1 mRNA in response to hypoxia.
Given this disparity and to address the relation of patient age to mutation frequency, we examined 10 exons of PIK3CA in 73 glioblastoma samples by PCR amplification followed by direct DNA sequencing.
Combination of all-trans retinoic acid and interferon-gamma suppressed PI3K/Akt survival pathway in glioblastoma T98G cells whereas NF-kappaB survival signaling in glioblastoma U87MG cells for induction of apoptosis.
Introduction of normal PTEN together with H-Ras(G12V) into U251 glioblastoma cells reduced the PI3K-dependent activation of Akt, but had no effect on vacuolation.
Rapamycin has anticancer activity in PTEN-deficient glioblastoma and warrants further clinical study alone or in combination with PI3K pathway inhibitors.
The suggested dependence of glioblastoma tumors on PI3K signaling implies that PI3K inhibitors should lead to effective killing of these cancer cells, but that has been shown not to be the case.
In addition, we demonstrate that the extracellular signal-regulated kinase (ERK)1/2 pathway is only partially implicated in the modulation of CXCL12-induced glioblastoma cell movement, whereas the phosphoinositol-3 kinase (PI3K) pathway is not involved.
These findings suggest that the PI3K/mTor signaling pathway is critical for the maintenance of glioblastoma CSLC properties, and targeting both mTor and PI3K of CSLCs may be an effective therapeutic strategy in glioblastoma.
Our findings suggest that there is p70S6K-mediated, cross-inhibitory regulation between the MEK/ERK and PI3K/mTOR pathways, in which each contribute to the maintenance of the self-renewal and tumorigenic capacity of glioblastoma CSLCs.
In the present study, we report decreased cell proliferation and invasive ability upon the LY294002-induced inhibition of PI3K in both U251 and LN229 human glioblastoma cells in vitro.
Insulin growth factor-2 binding protein 3 (IGF2BP3) is a glioblastoma-specific marker that activates phosphatidylinositol 3-kinase/mitogen-activated protein kinase (PI3K/MAPK) pathways by modulating IGF-2.
The PI3K pathway is commonly activated in glioblastoma and promotes tumor cell survival, suggesting that its inhibition would make cells more sensitive to cytotoxic agents.
CsA, comparably to pharmacological inhibitors of PI3K/Akt signaling (LY294002, A443654), reduced motility of glioblastoma cells, diminished MMP-2 gelatinolytic activity and MMP-2 and MT1-MMP expression.
We have investigated mTOR signaling in glioma cells with the allosteric mTORC1 inhibitor rapamycin, the mTORC1/2 inhibitor Ku-0063794, a dual PI3K/mTORC1/2 kinase inhibitor PI-103, and siRNA against raptor, rictor, or mTOR, and evaluated the value of mTOR inhibitors for the treatment of glioblastoma.
Pretreatment with PI3K inhibitor wortmannin and MEK1 inhibitor PD98059 prevented the mycelial fermentation-induced cytotoxicity in GBM8401 and U-87MG cells, suggesting the involvement of PI3K/Akt and MEK1 pathways in mycelial fermentation-driven glioblastoma cell apoptosis and autophagy.
PIK3R3, the gene that encodes the PI3K regulatory subunit p55γ, is over-expressed in glioblastoma and ovarian cancers, but its expression in gastric cancer (GC) is not known.