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PI3K pan-inhibition impairs more efficiently proliferation and survival of T-cell acute lymphoblastic leukemia cell lines when compared to isoform-selective PI3K inhibitors.

Lonetti A, Cappellini A, Spartà AM, Chiarini F, Buontempo F, Evangelisti C, Evangelisti C, Orsini E, McCubrey JA, Martelli AM - Oncotarget (2015)

Bottom Line: Intriguingly, the dual p110γ/δ inhibitor IPI-145 was effective in Loucy cells, which are representative of early T-precursor (ETP)-ALL, a T-ALL subtype associated with a poor outcome.PTEN gene deletion did not confer a peculiar reliance of T-ALL cells on PI3K activity for their proliferation/survival, as PTEN was inactivated in PTEN non deleted cells, due to posttranslational mechanisms.PI3K pan-inhibition suppressed Akt activation and induced caspase-independent apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.

ABSTRACT
Class I phosphatidylinositol 3-kinases (PI3Ks) are frequently activated in T-cell acute lymphoblastic leukemia (T-ALL), mainly due to the loss of PTEN function. Therefore, targeting PI3Ks is a promising innovative approach for T-ALL treatment, however at present no definitive evidence indicated which is the better therapeutic strategy between pan or selective isoform inhibition, as all the four catalytic subunits might participate in leukemogenesis. Here, we demonstrated that in both PTEN deleted and PTEN non deleted T-ALL cell lines, PI3K pan-inhibition exerted the highest cytotoxic effects when compared to both selective isoform inhibition or dual p110γ/δ inhibition. Intriguingly, the dual p110γ/δ inhibitor IPI-145 was effective in Loucy cells, which are representative of early T-precursor (ETP)-ALL, a T-ALL subtype associated with a poor outcome. PTEN gene deletion did not confer a peculiar reliance of T-ALL cells on PI3K activity for their proliferation/survival, as PTEN was inactivated in PTEN non deleted cells, due to posttranslational mechanisms. PI3K pan-inhibition suppressed Akt activation and induced caspase-independent apoptosis. We further demonstrated that in some T-ALL cell lines, autophagy could exert a protective role against PI3K inhibition. Our findings strongly support clinical application of class I PI3K pan-inhibitors in T-ALL treatment, with the possible exception of ETP-ALL cases.

No MeSH data available.


Related in: MedlinePlus

PI3K pan-inhibition impairs proliferation in T-ALL cell linesGrowth curves of T-ALL cell lines treated with 5 μM of PI3K selective and pan-inhibitors (A) or with increasing concentration (0.5, 1 and 5 μM) of the dual inhibitor IPI-145 (B). Viable cells were counted before treatment (0 h), and after 16, 24, 40, 48, 64 and 72 h of treatment. Cell growth was calculated as the percentage of viable cells compared to that at T 0 h. Four independent counts for each time point and two independent experiments for each cell line were performed (bars, SD). (C) Doubling time obtained from the cell count analysis. Increase in doubling time indicates a proliferation impairment. The negative doubling time observed in Jurkat cells indicates cell death induction. Asterisks indicate statistically significant differences with respect to untreated cells (*p < 0.05; **p < 0.01; ***p < 0.001). (D) Flow cytrometric analysis of the proliferation marker Ki-67. Cells were treated with 5 μM of the pan inhibitor ZSTK-474 for 72 h. Upper panel: control cells (untreated). Lower panels: treated cells.
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Figure 2: PI3K pan-inhibition impairs proliferation in T-ALL cell linesGrowth curves of T-ALL cell lines treated with 5 μM of PI3K selective and pan-inhibitors (A) or with increasing concentration (0.5, 1 and 5 μM) of the dual inhibitor IPI-145 (B). Viable cells were counted before treatment (0 h), and after 16, 24, 40, 48, 64 and 72 h of treatment. Cell growth was calculated as the percentage of viable cells compared to that at T 0 h. Four independent counts for each time point and two independent experiments for each cell line were performed (bars, SD). (C) Doubling time obtained from the cell count analysis. Increase in doubling time indicates a proliferation impairment. The negative doubling time observed in Jurkat cells indicates cell death induction. Asterisks indicate statistically significant differences with respect to untreated cells (*p < 0.05; **p < 0.01; ***p < 0.001). (D) Flow cytrometric analysis of the proliferation marker Ki-67. Cells were treated with 5 μM of the pan inhibitor ZSTK-474 for 72 h. Upper panel: control cells (untreated). Lower panels: treated cells.

Mentions: We investigated in more detail the effects of the PI3K pathway inhibition on cell proliferation, by analyzing the long-term cell growth over 3 days post-treatment with the drugs. The pan-inhibitor ZSTK-474 significantly impaired cell proliferation in all the cell lines, independently from PTEN status, whereas p110α and p110β inhibition produced negligible effects (Fig. 2A). Specific and dual inhibition of p110γ and p110δ isoforms displayed an irregular pattern. Jurkat and DND-41 cell proliferation was unaffected, conversely in Loucy and ALL-SIL cells either p110δ inhibition or dual p110γ/δ inhibition significantly impaired cell growth (Fig. 2A). Compared to untreated controls, ZSTK-474 markedly slowed down the doubling time in Loucy, DND-41, and ALL-SIL cells, whereas a negative doubling time was estimated in Jurkat cells, suggesting cell death induction (Fig. 2C). Importantly, in Loucy cells, the only cell line responsive to IPI-145, proliferation was impaired already at 0.5 μM after treatment with this dual inhibitor (Fig. 2B and 2C).


PI3K pan-inhibition impairs more efficiently proliferation and survival of T-cell acute lymphoblastic leukemia cell lines when compared to isoform-selective PI3K inhibitors.

Lonetti A, Cappellini A, Spartà AM, Chiarini F, Buontempo F, Evangelisti C, Evangelisti C, Orsini E, McCubrey JA, Martelli AM - Oncotarget (2015)

PI3K pan-inhibition impairs proliferation in T-ALL cell linesGrowth curves of T-ALL cell lines treated with 5 μM of PI3K selective and pan-inhibitors (A) or with increasing concentration (0.5, 1 and 5 μM) of the dual inhibitor IPI-145 (B). Viable cells were counted before treatment (0 h), and after 16, 24, 40, 48, 64 and 72 h of treatment. Cell growth was calculated as the percentage of viable cells compared to that at T 0 h. Four independent counts for each time point and two independent experiments for each cell line were performed (bars, SD). (C) Doubling time obtained from the cell count analysis. Increase in doubling time indicates a proliferation impairment. The negative doubling time observed in Jurkat cells indicates cell death induction. Asterisks indicate statistically significant differences with respect to untreated cells (*p < 0.05; **p < 0.01; ***p < 0.001). (D) Flow cytrometric analysis of the proliferation marker Ki-67. Cells were treated with 5 μM of the pan inhibitor ZSTK-474 for 72 h. Upper panel: control cells (untreated). Lower panels: treated cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
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Figure 2: PI3K pan-inhibition impairs proliferation in T-ALL cell linesGrowth curves of T-ALL cell lines treated with 5 μM of PI3K selective and pan-inhibitors (A) or with increasing concentration (0.5, 1 and 5 μM) of the dual inhibitor IPI-145 (B). Viable cells were counted before treatment (0 h), and after 16, 24, 40, 48, 64 and 72 h of treatment. Cell growth was calculated as the percentage of viable cells compared to that at T 0 h. Four independent counts for each time point and two independent experiments for each cell line were performed (bars, SD). (C) Doubling time obtained from the cell count analysis. Increase in doubling time indicates a proliferation impairment. The negative doubling time observed in Jurkat cells indicates cell death induction. Asterisks indicate statistically significant differences with respect to untreated cells (*p < 0.05; **p < 0.01; ***p < 0.001). (D) Flow cytrometric analysis of the proliferation marker Ki-67. Cells were treated with 5 μM of the pan inhibitor ZSTK-474 for 72 h. Upper panel: control cells (untreated). Lower panels: treated cells.
Mentions: We investigated in more detail the effects of the PI3K pathway inhibition on cell proliferation, by analyzing the long-term cell growth over 3 days post-treatment with the drugs. The pan-inhibitor ZSTK-474 significantly impaired cell proliferation in all the cell lines, independently from PTEN status, whereas p110α and p110β inhibition produced negligible effects (Fig. 2A). Specific and dual inhibition of p110γ and p110δ isoforms displayed an irregular pattern. Jurkat and DND-41 cell proliferation was unaffected, conversely in Loucy and ALL-SIL cells either p110δ inhibition or dual p110γ/δ inhibition significantly impaired cell growth (Fig. 2A). Compared to untreated controls, ZSTK-474 markedly slowed down the doubling time in Loucy, DND-41, and ALL-SIL cells, whereas a negative doubling time was estimated in Jurkat cells, suggesting cell death induction (Fig. 2C). Importantly, in Loucy cells, the only cell line responsive to IPI-145, proliferation was impaired already at 0.5 μM after treatment with this dual inhibitor (Fig. 2B and 2C).

Bottom Line: Intriguingly, the dual p110γ/δ inhibitor IPI-145 was effective in Loucy cells, which are representative of early T-precursor (ETP)-ALL, a T-ALL subtype associated with a poor outcome.PTEN gene deletion did not confer a peculiar reliance of T-ALL cells on PI3K activity for their proliferation/survival, as PTEN was inactivated in PTEN non deleted cells, due to posttranslational mechanisms.PI3K pan-inhibition suppressed Akt activation and induced caspase-independent apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.

ABSTRACT
Class I phosphatidylinositol 3-kinases (PI3Ks) are frequently activated in T-cell acute lymphoblastic leukemia (T-ALL), mainly due to the loss of PTEN function. Therefore, targeting PI3Ks is a promising innovative approach for T-ALL treatment, however at present no definitive evidence indicated which is the better therapeutic strategy between pan or selective isoform inhibition, as all the four catalytic subunits might participate in leukemogenesis. Here, we demonstrated that in both PTEN deleted and PTEN non deleted T-ALL cell lines, PI3K pan-inhibition exerted the highest cytotoxic effects when compared to both selective isoform inhibition or dual p110γ/δ inhibition. Intriguingly, the dual p110γ/δ inhibitor IPI-145 was effective in Loucy cells, which are representative of early T-precursor (ETP)-ALL, a T-ALL subtype associated with a poor outcome. PTEN gene deletion did not confer a peculiar reliance of T-ALL cells on PI3K activity for their proliferation/survival, as PTEN was inactivated in PTEN non deleted cells, due to posttranslational mechanisms. PI3K pan-inhibition suppressed Akt activation and induced caspase-independent apoptosis. We further demonstrated that in some T-ALL cell lines, autophagy could exert a protective role against PI3K inhibition. Our findings strongly support clinical application of class I PI3K pan-inhibitors in T-ALL treatment, with the possible exception of ETP-ALL cases.

No MeSH data available.


Related in: MedlinePlus