Phosphatidylinositol 3-kinase inhibition potentiates glucocorticoid response in B-cell acute lymphoblastic leukemia.

J Cell Physiol 2018 Mar 7;233(3):1796-1811. Epub 2017 Sep 7.

Institute of Molecular Genetics, Rizzoli Orthopedic Institute, National Research Council, Bologna, Italy.

Despite remarkable progress in polychemotherapy protocols, pediatric B-cell acute lymphoblastic leukemia (B-ALL) remains fatal in around 20% of cases. Hence, novel targeted therapies are needed for patients with poor prognosis. Glucocorticoids (GCs) are drugs commonly administrated for B-ALL treatment. Activation of the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin signaling pathway is frequently observed in B-ALL and contributes to GC-resistance. Here, we analyzed for the first time to our knowledge, the therapeutic potential of pan and isoform-selective PI3K p110 inhibitors, alone or combined with dexamethasone (DEX), in B-ALL leukemia cell lines and patient samples. We found that a pan PI3K p110 inhibitor displayed the most powerful cytotoxic effects in B-ALL cells, by inducing cell cycle arrest and apoptosis. Both a pan PI3K p110 inhibitor and a dual γ/δ PI3K p110 inhibitor sensitized B-ALL cells to DEX by restoring nuclear translocation of the GC receptor and counteracted stroma-induced DEX-resistance. Finally, gene expression analysis documented that, on one hand the combination consisting of a pan PI3K p110 inhibitor and DEX strengthened the DEX-induced up- or down-regulation of several genes involved in apoptosis, while on the other, it rescued the effects of genes that might be involved in GC-resistance. Overall, our findings strongly suggest that PI3K p110 inhibition could be a promising strategy for treating B-ALL patients by improving GC therapeutic effects and/or overcoming GC-resistance.

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http://dx.doi.org/10.1002/jcp.26135DOI Listing
March 2018
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References

(Supplied by CrossRef)
The non-conventional effects of glucocorticoids in cancer
Azher et al.
Journal of Cellular Physiology 2016
Glucocorticoid resistance in paediatric acute lymphoblastic leukaemia
Bhadri et al.
Journal of Paediatrics and Child Health 2012

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