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Am J Obstet Gynecol. 2013 Nov;209(5):465.e1-9. doi: 10.1016/j.ajog.2013.07.020. Epub 2013 Jul 24.

Oncogenic PIK3CA gene mutations and HER2/neu gene amplifications determine the sensitivity of uterine serous carcinoma cell lines to GDC-0980, a selective inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2).

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  • 1Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, CT.

Abstract

OBJECTIVE:

To evaluate PIK3CA mutational status and c-erbB2 gene amplification in a series of primary uterine serous carcinomas (USC) cell lines. To assess the efficacy of GDC-0980, a potent inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2), against primary USC harboring HER2/neu gene amplification and/or PIK3CA mutations.

STUDY DESIGN:

Twenty-two primary USC cell lines were evaluated for c-erbB2 oncogene amplification by fluorescence in situ hybridization (FISH) assays and for PIK3CA gene mutations by direct DNA sequencing of exons 9 and 20. In vitro sensitivity to GDC-0980 was evaluated by flow-cytometry-based viability and proliferation assays. Downstream cellular responses to GDC-0980 were assessed by measuring phosphorylation of the 4-EBP1 protein by flow-cytometry.

RESULTS:

Five of 22 (22.7%) USC cell lines contained oncogenic PIK3CA mutations although 9 (40.9%) harbored c-erbB2 gene amplification by FISH. GDC-0980 caused a strong differential growth inhibition in FISH+ USC when compared with FISH- (GDC-0980 IC50 mean ± SEM = 0.29 ± 0.05 μM in FISH+ vs 1.09 ± 0.20 μM in FISH- tumors, P = .02). FISH+ USC harboring PIK3CA mutations were significantly more sensitive to GDC-0980 exposure when compared with USC cell lines harboring wild-type PIK3CA (P = .03). GDC-0980 growth-inhibition was associated with a significant and dose-dependent decline in phosphorylated 4-EBP1 levels.

CONCLUSION:

Oncogenic PIK3CA mutations and c-erbB2 gene amplification may represent biomarkers to identify patients harboring USC who may benefit most from the use of GDC-0980.

Copyright © 2013 Mosby, Inc. All rights reserved.

KEYWORDS:

GDC-0980; HER2/neu; PIK3CA; endometrial neoplasms; mTOR inhibitor; uterine serous tumors

[PubMed - indexed for MEDLINE]
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