Limits...
Pharmacological targeting of the PI3K/mTOR pathway alters the release of angioregulatory mediators both from primary human acute myeloid leukemia cells and their neighboring stromal cells.

Reikvam H, Nepstad I, Bruserud Ø, Hatfield KJ - Oncotarget (2013)

Bottom Line: Hierarchical clustering analysis showed that disruption of PI3K/Akt/mTOR pathways decreased AML cell release of CXCL8-11 for a large subset of patients, whereas the effects on other mediators were divergent.Various stromal cells (endothelial cells, fibroblasts, cells with osteoblastic phenotype) also showed constitutive release of angioregulatory mediators, and inhibitors of both the PI3K and mTOR pathway had anti-proliferative effects on stromal cells and resulted in decreased release of these angioregulatory mediators.PI3K and mTOR inhibitors can decrease constitutive cytokine release both by AML and stromal cells, suggesting potential direct and indirect antileukemic effects.

View Article: PubMed Central - PubMed

Affiliation: Section for Hematology, Department of Clinical Science, University of Bergen, Norway.

ABSTRACT
Acute myeloid leukemia (AML) is a heterogeneous and aggressive malignancy with poor overall survival. Constitutive as well as cytokine-initiated activation of PI3K/Akt/mTOR signaling is a common feature of AML patients, and inhibition of this pathway is considered as a possible therapeutic strategy in AML. Human AML cells and different stromal cell populations were cultured under highly standardized in vitro conditions. We investigated the effects of mTOR inhibitors (rapamycin and temsirolimus) and PI3K inhibitors (GDC-0941 and 3-methyladenin (3-MA)) on cell proliferation and the constitutive release of angioregulatory mediators by AML and stromal cells. Primary human AML cells were heterogeneous, though most patients showed high CXCL8 levels and detectable release of CXCL10, Ang-1, HGF and MMP-9. Hierarchical clustering analysis showed that disruption of PI3K/Akt/mTOR pathways decreased AML cell release of CXCL8-11 for a large subset of patients, whereas the effects on other mediators were divergent. Various stromal cells (endothelial cells, fibroblasts, cells with osteoblastic phenotype) also showed constitutive release of angioregulatory mediators, and inhibitors of both the PI3K and mTOR pathway had anti-proliferative effects on stromal cells and resulted in decreased release of these angioregulatory mediators. PI3K and mTOR inhibitors can decrease constitutive cytokine release both by AML and stromal cells, suggesting potential direct and indirect antileukemic effects.

Show MeSH

Related in: MedlinePlus

Associations between mRNA levels and supernatant protein levels for HGF and Ang-2mRNA levels in primary AML cells were compared with proteins levels measured after AML cell culture for 24 hours. (LEFT) Both mRNA and supernatant protein levels were available for 31 patients, and mRNA HGF levels differed significantly when comparing the 19 patients with detectable constitutive HGF secretion (grey box) with the 12 patients showing no detectable HGF release (white box) (Mann-Whitney U-test, p=0.0079). (RIGHT) mRNA Ang-2 levels showed a significant correlation with the Ang-2 protein concentration in culture supernatants of AML cells derived from 13 patients (p=0.0245, r=0.618, Pearson's correlation).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3757241&req=5

Figure 3: Associations between mRNA levels and supernatant protein levels for HGF and Ang-2mRNA levels in primary AML cells were compared with proteins levels measured after AML cell culture for 24 hours. (LEFT) Both mRNA and supernatant protein levels were available for 31 patients, and mRNA HGF levels differed significantly when comparing the 19 patients with detectable constitutive HGF secretion (grey box) with the 12 patients showing no detectable HGF release (white box) (Mann-Whitney U-test, p=0.0079). (RIGHT) mRNA Ang-2 levels showed a significant correlation with the Ang-2 protein concentration in culture supernatants of AML cells derived from 13 patients (p=0.0245, r=0.618, Pearson's correlation).

Mentions: We used microarray analysis to examine mRNA levels in non-cultured leukemia cells for 31 of the 60 AML patients investigated for their constitutive cytokine release. We performed both (i) correlation analysis between detectable cytokine protein levels and mRNA levels and (ii) comparison of mRNA levels for patients with detectable and undetectable cytokine levels. For most of the angioregulatory mediators we did not find any significant correlations between protein/mRNA levels or difference in mRNA levels between patients with detectable and undetectable mediator release. However, two exceptions were seen: (i) patients with undetectable HGF release had a significantly lower HGF-mRNA expression (p=0.0079, Mann-Whitney U-test, Fig. 3); and (ii) Ang-2 mRNA expression showed a significant correlation with supernatant protein levels (p=0.0245, r=0.618, Pearson's correlation, Fig. 3). Thus, only these two cytokines show evidence for a regulation of protein expression at the mRNA level.


Pharmacological targeting of the PI3K/mTOR pathway alters the release of angioregulatory mediators both from primary human acute myeloid leukemia cells and their neighboring stromal cells.

Reikvam H, Nepstad I, Bruserud Ø, Hatfield KJ - Oncotarget (2013)

Associations between mRNA levels and supernatant protein levels for HGF and Ang-2mRNA levels in primary AML cells were compared with proteins levels measured after AML cell culture for 24 hours. (LEFT) Both mRNA and supernatant protein levels were available for 31 patients, and mRNA HGF levels differed significantly when comparing the 19 patients with detectable constitutive HGF secretion (grey box) with the 12 patients showing no detectable HGF release (white box) (Mann-Whitney U-test, p=0.0079). (RIGHT) mRNA Ang-2 levels showed a significant correlation with the Ang-2 protein concentration in culture supernatants of AML cells derived from 13 patients (p=0.0245, r=0.618, Pearson's correlation).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3757241&req=5

Figure 3: Associations between mRNA levels and supernatant protein levels for HGF and Ang-2mRNA levels in primary AML cells were compared with proteins levels measured after AML cell culture for 24 hours. (LEFT) Both mRNA and supernatant protein levels were available for 31 patients, and mRNA HGF levels differed significantly when comparing the 19 patients with detectable constitutive HGF secretion (grey box) with the 12 patients showing no detectable HGF release (white box) (Mann-Whitney U-test, p=0.0079). (RIGHT) mRNA Ang-2 levels showed a significant correlation with the Ang-2 protein concentration in culture supernatants of AML cells derived from 13 patients (p=0.0245, r=0.618, Pearson's correlation).
Mentions: We used microarray analysis to examine mRNA levels in non-cultured leukemia cells for 31 of the 60 AML patients investigated for their constitutive cytokine release. We performed both (i) correlation analysis between detectable cytokine protein levels and mRNA levels and (ii) comparison of mRNA levels for patients with detectable and undetectable cytokine levels. For most of the angioregulatory mediators we did not find any significant correlations between protein/mRNA levels or difference in mRNA levels between patients with detectable and undetectable mediator release. However, two exceptions were seen: (i) patients with undetectable HGF release had a significantly lower HGF-mRNA expression (p=0.0079, Mann-Whitney U-test, Fig. 3); and (ii) Ang-2 mRNA expression showed a significant correlation with supernatant protein levels (p=0.0245, r=0.618, Pearson's correlation, Fig. 3). Thus, only these two cytokines show evidence for a regulation of protein expression at the mRNA level.

Bottom Line: Hierarchical clustering analysis showed that disruption of PI3K/Akt/mTOR pathways decreased AML cell release of CXCL8-11 for a large subset of patients, whereas the effects on other mediators were divergent.Various stromal cells (endothelial cells, fibroblasts, cells with osteoblastic phenotype) also showed constitutive release of angioregulatory mediators, and inhibitors of both the PI3K and mTOR pathway had anti-proliferative effects on stromal cells and resulted in decreased release of these angioregulatory mediators.PI3K and mTOR inhibitors can decrease constitutive cytokine release both by AML and stromal cells, suggesting potential direct and indirect antileukemic effects.

View Article: PubMed Central - PubMed

Affiliation: Section for Hematology, Department of Clinical Science, University of Bergen, Norway.

ABSTRACT
Acute myeloid leukemia (AML) is a heterogeneous and aggressive malignancy with poor overall survival. Constitutive as well as cytokine-initiated activation of PI3K/Akt/mTOR signaling is a common feature of AML patients, and inhibition of this pathway is considered as a possible therapeutic strategy in AML. Human AML cells and different stromal cell populations were cultured under highly standardized in vitro conditions. We investigated the effects of mTOR inhibitors (rapamycin and temsirolimus) and PI3K inhibitors (GDC-0941 and 3-methyladenin (3-MA)) on cell proliferation and the constitutive release of angioregulatory mediators by AML and stromal cells. Primary human AML cells were heterogeneous, though most patients showed high CXCL8 levels and detectable release of CXCL10, Ang-1, HGF and MMP-9. Hierarchical clustering analysis showed that disruption of PI3K/Akt/mTOR pathways decreased AML cell release of CXCL8-11 for a large subset of patients, whereas the effects on other mediators were divergent. Various stromal cells (endothelial cells, fibroblasts, cells with osteoblastic phenotype) also showed constitutive release of angioregulatory mediators, and inhibitors of both the PI3K and mTOR pathway had anti-proliferative effects on stromal cells and resulted in decreased release of these angioregulatory mediators. PI3K and mTOR inhibitors can decrease constitutive cytokine release both by AML and stromal cells, suggesting potential direct and indirect antileukemic effects.

Show MeSH
Related in: MedlinePlus