(1) Amplification of EGFR was observed in well-characterised TNBCs (up to 92%); (2) qPCR correlated with SISH with 94% specificity and 75.6% sensitivity; (3) IHC correlated with SISH with 97% sensitivity and 78% specificity; (4) no EGFR, Kras mutations or EML4-ALK translocations were found, but PI3K and Braf mutations were observed in 26% of cases; and (5) small, acentric circular extrachromosomal DNA similar to 'double minutes' in glioblastomas was observed in 18% of SISH sections.
Applied to data from the Cancer Genome Atlas (TCGA), the method identifies the principal known altered modules in glioblastoma (GBM) and highlights the striking mutual exclusivity of genomic alterations in the PI(3)K, p53, and Rb pathways.
Genomic analyses reveal that signature genetic lesions in GBM and LGG include copy gain and amplification of chromosome 7, amplification, mutation, and overexpression of receptor tyrosine kinases (RTK) such as EGFR, and activating mutations in components of the PI3K pathway.
Glioblastoma (GBM) genomes feature recurrent genetic alterations that dysregulate core intracellular signaling pathways, including the G1/S cell cycle checkpoint and the MAPK and PI3K effector arms of receptor tyrosine kinase (RTK) signaling.
Recently, a large-scale mutational analysis of eight PI3K and eight PI3K-like genes revealed somatic mutations in PIK3CA, which encodes the p110alpha catalytic subunit of class IA PI3K, in several types of cancer, including glioblastoma multiforme.
The Cancer Genome Atlas integrative analysis of GBM reported the striking finding of genetic alterations in the p53 and PI3K pathways in more than 80% of GBMs.
Glioblastomas frequently carry genetic alterations resulting in an aberrant activation of the phosphoinositol-3-kinase (Pi3k)/protein kinase B (Akt) signalling pathway, including most notably phosphatase and tensin homolog (PTEN) mutation, epidermal growth factor receptor (EGFR) amplification and rearrangement, as well as carboxyl-terminal modulator protein (CTMP) hypermethylation [Knobbe et al., (2004) Hypermethylation and transcriptional downregulation of the carboxyl-terminal modulator protein gene in glioblastomas.J Natl Cancer Institute, 96, 483-486].
Here, we report on the analysis of 17 genes related to the Pi3k/Akt signalling pathway for genetic alteration and aberrant expression in a series of 103 glioblastomas.
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.
Typical molecular changes in glioblastoma include mutations in genes regulating receptor tyrosine kinase (RTK)/rat sarcoma (RAS)/phosphoinositide 3-kinase (PI3K), p53, and retinoblastoma protein (RB) signaling.
However, there is reason for renewed optimism given the now very detailed knowledge of the cancer genome in GBM and a wealth of novel compounds entering the clinic, including next generation RTK inhibitors, class I PI3K inhibitors, mTOR kinase inhibitors (TORKinibs), and dual PI3(K)/mTOR inhibitors.
We synthesized Gint4.T-conjugated PNPs able of high uptake into U87MG glioblastoma (GBM) cells and with astonishing EC<sub>50</sub> value (38 pM) when loaded with a PI3K-mTOR inhibitor.
Overall, our findings propose that miR-579 functions as a novel tumor suppressor gene in GBM by regulating the PI3K/AKT signaling pathway and may serve as a therapeutic target for clinical therapy of glioblastoma multiform.
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.
In conclusion, the combined inhibition of PI3K/Akt/mTOR and SHH pathways was superior to single pathway inhibition in suppressing glioblastoma growth by targeting GICs.
The EGFR and PI3K/mTORC1/2 pathways are frequently altered in glioblastoma (GBM), but pharmacologic targeting of EGFR and PI3K signaling has failed to demonstrate efficacy in clinical trials.
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.
Mutations in TERT, CDKN2A/CDKN2B, EGFR, and PI3K pathway were commonly observed in both primary and recurrent GBM revealing their prognostic and therapeutic potential.