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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 demonstrates increased synergy with rapamycin in PTEN deficient cell lines.(A) PTEN wild type (TC-32, A673, RD) or PTEN  (A4573) cell lines were exposed to a series of 1.5-fold dilutions of buparlisib and rapamycin alone or in combination at a constant ratio of 20:3 (TC-32, A673, RD) or 100:3 (A4573) for 72 hours, then cell viability was determined by MTT assay. Columns represent the average of three independent experiments, error bars represent standard deviation. Combination index values greater than 1, equal to 1, or less than one indicate antagonism, additivity, or synergy. (B) Isobologram plot of the effect of buparlisib combined with rapamycin. The effective doses of rapamycin and buparlisib are plotted on the x- and y-axis with lines of linear additivity connecting the ED50, ED75, and E90 for individual treatments. Points for combination treatment above, on, or below the lines indicate antagonism, additivity, or synergy, respectively. (C) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, and actin in A4573 cells after 1 hour of treatment with buparlisib, rapamycin, or both. (D) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, cleaved PARP, and actin in A4573 cells after 24 hours of treatment with buparlisib, rapamycin, or both.
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pone.0133610.g007: Buparlisib demonstrates increased synergy with rapamycin in PTEN deficient cell lines.(A) PTEN wild type (TC-32, A673, RD) or PTEN (A4573) cell lines were exposed to a series of 1.5-fold dilutions of buparlisib and rapamycin alone or in combination at a constant ratio of 20:3 (TC-32, A673, RD) or 100:3 (A4573) for 72 hours, then cell viability was determined by MTT assay. Columns represent the average of three independent experiments, error bars represent standard deviation. Combination index values greater than 1, equal to 1, or less than one indicate antagonism, additivity, or synergy. (B) Isobologram plot of the effect of buparlisib combined with rapamycin. The effective doses of rapamycin and buparlisib are plotted on the x- and y-axis with lines of linear additivity connecting the ED50, ED75, and E90 for individual treatments. Points for combination treatment above, on, or below the lines indicate antagonism, additivity, or synergy, respectively. (C) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, and actin in A4573 cells after 1 hour of treatment with buparlisib, rapamycin, or both. (D) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, cleaved PARP, and actin in A4573 cells after 24 hours of treatment with buparlisib, rapamycin, or both.

Mentions: While PTEN status did not correlate with sensitivity to buparlisib as a single agent, it appears lower PTEN expression may render cells more sensitive to buparlisib when combined with other agents that inhibit Akt signaling. Based on these results, we investigated whether combination with other targeted agents can display similar effects. Since Akt is also activated upon rapamycin treatment, we evaluated the effects of combining rapamycin with buparlisib. Synergy was observed in the four cell lines tested, with the greatest effects observed in A4573 cells (Fig 7A and 7B). The addition of buparlisib reduced rapamycin-mediated Akt activation and treatment with both drugs more potently suppressed phosphorylation of 4E-BP1 (Fig 7C and 7D). Unlike NVP-AEW541, the drug combination did not increase apoptosis (Fig 7D).


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 demonstrates increased synergy with rapamycin in PTEN deficient cell lines.(A) PTEN wild type (TC-32, A673, RD) or PTEN  (A4573) cell lines were exposed to a series of 1.5-fold dilutions of buparlisib and rapamycin alone or in combination at a constant ratio of 20:3 (TC-32, A673, RD) or 100:3 (A4573) for 72 hours, then cell viability was determined by MTT assay. Columns represent the average of three independent experiments, error bars represent standard deviation. Combination index values greater than 1, equal to 1, or less than one indicate antagonism, additivity, or synergy. (B) Isobologram plot of the effect of buparlisib combined with rapamycin. The effective doses of rapamycin and buparlisib are plotted on the x- and y-axis with lines of linear additivity connecting the ED50, ED75, and E90 for individual treatments. Points for combination treatment above, on, or below the lines indicate antagonism, additivity, or synergy, respectively. (C) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, and actin in A4573 cells after 1 hour of treatment with buparlisib, rapamycin, or both. (D) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, cleaved PARP, and actin in A4573 cells after 24 hours of treatment with buparlisib, rapamycin, or both.
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pone.0133610.g007: Buparlisib demonstrates increased synergy with rapamycin in PTEN deficient cell lines.(A) PTEN wild type (TC-32, A673, RD) or PTEN (A4573) cell lines were exposed to a series of 1.5-fold dilutions of buparlisib and rapamycin alone or in combination at a constant ratio of 20:3 (TC-32, A673, RD) or 100:3 (A4573) for 72 hours, then cell viability was determined by MTT assay. Columns represent the average of three independent experiments, error bars represent standard deviation. Combination index values greater than 1, equal to 1, or less than one indicate antagonism, additivity, or synergy. (B) Isobologram plot of the effect of buparlisib combined with rapamycin. The effective doses of rapamycin and buparlisib are plotted on the x- and y-axis with lines of linear additivity connecting the ED50, ED75, and E90 for individual treatments. Points for combination treatment above, on, or below the lines indicate antagonism, additivity, or synergy, respectively. (C) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, and actin in A4573 cells after 1 hour of treatment with buparlisib, rapamycin, or both. (D) Immunoblot analysis of phospho-Akt (S473), total Akt, phospho-4E-BP1 (T37/46), total 4E-BP1, cleaved PARP, and actin in A4573 cells after 24 hours of treatment with buparlisib, rapamycin, or both.
Mentions: While PTEN status did not correlate with sensitivity to buparlisib as a single agent, it appears lower PTEN expression may render cells more sensitive to buparlisib when combined with other agents that inhibit Akt signaling. Based on these results, we investigated whether combination with other targeted agents can display similar effects. Since Akt is also activated upon rapamycin treatment, we evaluated the effects of combining rapamycin with buparlisib. Synergy was observed in the four cell lines tested, with the greatest effects observed in A4573 cells (Fig 7A and 7B). The addition of buparlisib reduced rapamycin-mediated Akt activation and treatment with both drugs more potently suppressed phosphorylation of 4E-BP1 (Fig 7C and 7D). Unlike NVP-AEW541, the drug combination did not increase apoptosis (Fig 7D).

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