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Evaluation of In Vitro Activity of the Class I PI3K Inhibitor Buparlisib (BKM120) in Pediatric Bone and Soft Tissue Sarcomas.

Anderson JL, Park A, Akiyama R, Tap WD, Denny CT, Federman N - PLoS ONE (2015)

Bottom Line: Anti-proliferative effects were observed in both anchorage dependent and independent conditions and apoptosis was induced within 24 hours of drug treatment.Buparlisib demonstrated cytotoxicity as a single agent, but was found to be more effective when used in combination.The addition of NVP-AEW541 also further reduced phospho-Akt levels and more potently induced apoptosis compared to buparlisib treatment alone.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Division of Hematology/Oncology, Gwynne Hazen Cherry Memorial Laboratories, University of California, Los Angeles, Los Angeles, California, United States of America.

ABSTRACT
Pediatric bone and soft tissue sarcomas often display increased Akt phosphorylation through up regulation of insulin-like growth factor (IGF1) signaling. Additionally, Akt signaling has been linked to resistance to IGF1 receptor (IGF1R) and mTOR (mammalian target of rapamycin) inhibitors in sarcoma, further demonstrating the role of Akt in tumor survival. This suggests targeting components of the PI3K/Akt pathway may be an effective therapeutic strategy. Here, we investigated the in vitro activity of the pan-class I PI3K inhibitor buparlisib (BKM120) in pediatric bone and soft tissue sarcomas. Buparlisib inhibited activation of Akt and signaling molecules downstream of mTORC1 (mTOR complex 1) in Ewing sarcoma, osteosarcoma, and rhabdomyosarcoma cell lines. Anti-proliferative effects were observed in both anchorage dependent and independent conditions and apoptosis was induced within 24 hours of drug treatment. Buparlisib demonstrated cytotoxicity as a single agent, but was found to be more effective when used in combination. Synergy was observed when buparlisib was combined with the IGF1R inhibitor NVP-AEW541 and the mTORC1 inhibitor rapamycin. The addition of NVP-AEW541 also further reduced phospho-Akt levels and more potently induced apoptosis compared to buparlisib treatment alone. Additionally, the combination of buparlisib with the MEK1/2 inhibitor trametinib resulted in synergy in sarcoma cell lines possessing MAPK pathway mutations. Taken together, these data indicate buparlisib could be a novel therapy for the treatment of pediatric bone and soft tissue sarcomas.

No MeSH data available.


Related in: MedlinePlus

Buparlisib inhibits proliferation of pediatric sarcoma cell lines.(A) Cells were treated with media containing 0.1% DMSO or concentrations of buparlisib ranging from 10 nM to 10 μM for 72 hours. Cell viability was determined by MTT assay. Percent cell viability was plotted against log buparlisib concentration and IC50 values were calculated by fitting this data to a four-parameter, variable slope sigmoid dose-response model. Each point is the average of at least three independent experiments. (B) Cell viability IC50 values for pediatric sarcoma cell lines. Columns represent the average of at least three independent experiments, error bars represent 95% confidence intervals. Dashed line indicates median IC50. (C) Scatter plot showing the low correlation (R2 = 0.07311) between cell viability and phospho-Akt IC50 values. The cell lines that possess the lowest (A204) and highest (A4573) phospho-Akt IC50s are indicated on the graph. Dot colors indicate sarcoma type: gray—ES, blue—OS, burgundy—RMS.
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pone.0133610.g004: Buparlisib inhibits proliferation of pediatric sarcoma cell lines.(A) Cells were treated with media containing 0.1% DMSO or concentrations of buparlisib ranging from 10 nM to 10 μM for 72 hours. Cell viability was determined by MTT assay. Percent cell viability was plotted against log buparlisib concentration and IC50 values were calculated by fitting this data to a four-parameter, variable slope sigmoid dose-response model. Each point is the average of at least three independent experiments. (B) Cell viability IC50 values for pediatric sarcoma cell lines. Columns represent the average of at least three independent experiments, error bars represent 95% confidence intervals. Dashed line indicates median IC50. (C) Scatter plot showing the low correlation (R2 = 0.07311) between cell viability and phospho-Akt IC50 values. The cell lines that possess the lowest (A204) and highest (A4573) phospho-Akt IC50s are indicated on the graph. Dot colors indicate sarcoma type: gray—ES, blue—OS, burgundy—RMS.

Mentions: After demonstrating that buparlisib inhibits PI3K/Akt signaling, we examined its anti-proliferative effects in a panel of sarcoma cell lines. Cell viabilities of 11 ES, 8 OS, and 3 RMS cell lines were measured after 72 hours of drug treatment. Cell viabilities of drug treated cells were normalized to those of cells grown in media without drug and fit to a dose-response curve to calculate IC50 values (Fig 4A). All cell lines were sensitive to buparlisib, with IC50 values that ranged from approximately 560 nM to 1.9 μM (S1 Table). In general, ES and RMS cell lines displayed IC50 values near 1.0 μM, while OS cell lines displayed slightly higher values (Fig 4B and S1 Table). MCF-7 cells containing the E545K PIK3CA mutation displayed a lower IC50 of 173 nM, despite having a similar phospho-Akt IC50 (S1B–S1D Fig, S1 Table). Additionally, IC50 values for buparlisib were higher than for the pan-PI3K inhibitor GDC-0941 in sarcoma cell lines (S3 Fig, S1 Table). Sensitivity to buparlisib treatment did not correlate with PTEN expression or basal phospho-Akt levels (Fig 1A and S1 Table). While the cell line with the lowest phospho-Akt IC50 was the most sensitive to buparlisib (A204), overall there was minimal correlation between Akt phosphorylation and cell viability IC50 values (Fig 4C). This agrees with a prior study that demonstrated increased buparlisib sensitivity only in cell lines with an activating PIK3CA mutation [21].


Evaluation of In Vitro Activity of the Class I PI3K Inhibitor Buparlisib (BKM120) in Pediatric Bone and Soft Tissue Sarcomas.

Anderson JL, Park A, Akiyama R, Tap WD, Denny CT, Federman N - PLoS ONE (2015)

Buparlisib inhibits proliferation of pediatric sarcoma cell lines.(A) Cells were treated with media containing 0.1% DMSO or concentrations of buparlisib ranging from 10 nM to 10 μM for 72 hours. Cell viability was determined by MTT assay. Percent cell viability was plotted against log buparlisib concentration and IC50 values were calculated by fitting this data to a four-parameter, variable slope sigmoid dose-response model. Each point is the average of at least three independent experiments. (B) Cell viability IC50 values for pediatric sarcoma cell lines. Columns represent the average of at least three independent experiments, error bars represent 95% confidence intervals. Dashed line indicates median IC50. (C) Scatter plot showing the low correlation (R2 = 0.07311) between cell viability and phospho-Akt IC50 values. The cell lines that possess the lowest (A204) and highest (A4573) phospho-Akt IC50s are indicated on the graph. Dot colors indicate sarcoma type: gray—ES, blue—OS, burgundy—RMS.
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Related In: Results  -  Collection

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pone.0133610.g004: Buparlisib inhibits proliferation of pediatric sarcoma cell lines.(A) Cells were treated with media containing 0.1% DMSO or concentrations of buparlisib ranging from 10 nM to 10 μM for 72 hours. Cell viability was determined by MTT assay. Percent cell viability was plotted against log buparlisib concentration and IC50 values were calculated by fitting this data to a four-parameter, variable slope sigmoid dose-response model. Each point is the average of at least three independent experiments. (B) Cell viability IC50 values for pediatric sarcoma cell lines. Columns represent the average of at least three independent experiments, error bars represent 95% confidence intervals. Dashed line indicates median IC50. (C) Scatter plot showing the low correlation (R2 = 0.07311) between cell viability and phospho-Akt IC50 values. The cell lines that possess the lowest (A204) and highest (A4573) phospho-Akt IC50s are indicated on the graph. Dot colors indicate sarcoma type: gray—ES, blue—OS, burgundy—RMS.
Mentions: After demonstrating that buparlisib inhibits PI3K/Akt signaling, we examined its anti-proliferative effects in a panel of sarcoma cell lines. Cell viabilities of 11 ES, 8 OS, and 3 RMS cell lines were measured after 72 hours of drug treatment. Cell viabilities of drug treated cells were normalized to those of cells grown in media without drug and fit to a dose-response curve to calculate IC50 values (Fig 4A). All cell lines were sensitive to buparlisib, with IC50 values that ranged from approximately 560 nM to 1.9 μM (S1 Table). In general, ES and RMS cell lines displayed IC50 values near 1.0 μM, while OS cell lines displayed slightly higher values (Fig 4B and S1 Table). MCF-7 cells containing the E545K PIK3CA mutation displayed a lower IC50 of 173 nM, despite having a similar phospho-Akt IC50 (S1B–S1D Fig, S1 Table). Additionally, IC50 values for buparlisib were higher than for the pan-PI3K inhibitor GDC-0941 in sarcoma cell lines (S3 Fig, S1 Table). Sensitivity to buparlisib treatment did not correlate with PTEN expression or basal phospho-Akt levels (Fig 1A and S1 Table). While the cell line with the lowest phospho-Akt IC50 was the most sensitive to buparlisib (A204), overall there was minimal correlation between Akt phosphorylation and cell viability IC50 values (Fig 4C). This agrees with a prior study that demonstrated increased buparlisib sensitivity only in cell lines with an activating PIK3CA mutation [21].

Bottom Line: Anti-proliferative effects were observed in both anchorage dependent and independent conditions and apoptosis was induced within 24 hours of drug treatment.Buparlisib demonstrated cytotoxicity as a single agent, but was found to be more effective when used in combination.The addition of NVP-AEW541 also further reduced phospho-Akt levels and more potently induced apoptosis compared to buparlisib treatment alone.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Division of Hematology/Oncology, Gwynne Hazen Cherry Memorial Laboratories, University of California, Los Angeles, Los Angeles, California, United States of America.

ABSTRACT
Pediatric bone and soft tissue sarcomas often display increased Akt phosphorylation through up regulation of insulin-like growth factor (IGF1) signaling. Additionally, Akt signaling has been linked to resistance to IGF1 receptor (IGF1R) and mTOR (mammalian target of rapamycin) inhibitors in sarcoma, further demonstrating the role of Akt in tumor survival. This suggests targeting components of the PI3K/Akt pathway may be an effective therapeutic strategy. Here, we investigated the in vitro activity of the pan-class I PI3K inhibitor buparlisib (BKM120) in pediatric bone and soft tissue sarcomas. Buparlisib inhibited activation of Akt and signaling molecules downstream of mTORC1 (mTOR complex 1) in Ewing sarcoma, osteosarcoma, and rhabdomyosarcoma cell lines. Anti-proliferative effects were observed in both anchorage dependent and independent conditions and apoptosis was induced within 24 hours of drug treatment. Buparlisib demonstrated cytotoxicity as a single agent, but was found to be more effective when used in combination. Synergy was observed when buparlisib was combined with the IGF1R inhibitor NVP-AEW541 and the mTORC1 inhibitor rapamycin. The addition of NVP-AEW541 also further reduced phospho-Akt levels and more potently induced apoptosis compared to buparlisib treatment alone. Additionally, the combination of buparlisib with the MEK1/2 inhibitor trametinib resulted in synergy in sarcoma cell lines possessing MAPK pathway mutations. Taken together, these data indicate buparlisib could be a novel therapy for the treatment of pediatric bone and soft tissue sarcomas.

No MeSH data available.


Related in: MedlinePlus