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Preclinical evaluation of the PARP inhibitor BMN-673 for the treatment of ovarian clear cell cancer


Wilkerson, Paul M; Dedes, Konstantin J; Samartzis, Eleftherios Pierre; Dedes, Ioannis; Lambros, Maryou B; Natrajan, Rachael; Gauthier, Arnaud; Piscuoglio, Salvatore; Töpfer, Chantal; Vukovic, Vesna; Daley, Frances; Weigelt, Britta; Reis-Filho, Jorge S (2017). Preclinical evaluation of the PARP inhibitor BMN-673 for the treatment of ovarian clear cell cancer. OncoTarget, 8(4):6057-6066.

Abstract

PURPOSE To determine if models of ovarian clear cell carcinomas (OCCCs) harbouring defects in homologous recombination (HR) DNA repair of double strand breaks (DSBs) are sensitive to cisplatin and/or PARP inhibition.
EXPERIMENTAL DESIGN The HR status of 12 OCCC cell lines was determined using RAD51/γH2AX foci formation assays. Sensitivity to cisplatin and the PARP inhibitor BMN-673 was correlated with HR status. BRCA1, BRCA2, MRE11 and PTEN loss of expression was investigated as a potential determinant of BMN-673 sensitivity. A tissue microarray containing 50 consecutive primary OCCC was assessed for PTEN expression using immunohistochemistry.
RESULTS A subset of OCCC cells displayed reduced RAD51 foci formation in the presence of DNA DSBs, suggestive of HR defects. HR-defective OCCC cells, with the exception of KOC-7c, had higher sensitivity to cisplatin/ BMN-673 than HR-competent OCCC cell lines (Log10 SF50 -9.4 (SD +/- 0.29) vs -8.1 (SD +/- 0.35), mean difference 1.3, p < 0.01). Of the cell lines studied, two, TOV-21G and KOC-7c, showed loss of PTEN expression. In primary OCCCs, loss of PTEN expression was observed in 10% (5/49) of cases.
CONCLUSIONS A subset of OCCC cells are sensitive to PARP inhibition in vitro, which can be predicted by HR defects as defined by γH2AX/RAD51 foci formation. These results provide a rationale for the testing of HR deficiency and PARP inhibitors as a targeted therapy in a subset of OCCCs.

Abstract

PURPOSE To determine if models of ovarian clear cell carcinomas (OCCCs) harbouring defects in homologous recombination (HR) DNA repair of double strand breaks (DSBs) are sensitive to cisplatin and/or PARP inhibition.
EXPERIMENTAL DESIGN The HR status of 12 OCCC cell lines was determined using RAD51/γH2AX foci formation assays. Sensitivity to cisplatin and the PARP inhibitor BMN-673 was correlated with HR status. BRCA1, BRCA2, MRE11 and PTEN loss of expression was investigated as a potential determinant of BMN-673 sensitivity. A tissue microarray containing 50 consecutive primary OCCC was assessed for PTEN expression using immunohistochemistry.
RESULTS A subset of OCCC cells displayed reduced RAD51 foci formation in the presence of DNA DSBs, suggestive of HR defects. HR-defective OCCC cells, with the exception of KOC-7c, had higher sensitivity to cisplatin/ BMN-673 than HR-competent OCCC cell lines (Log10 SF50 -9.4 (SD +/- 0.29) vs -8.1 (SD +/- 0.35), mean difference 1.3, p < 0.01). Of the cell lines studied, two, TOV-21G and KOC-7c, showed loss of PTEN expression. In primary OCCCs, loss of PTEN expression was observed in 10% (5/49) of cases.
CONCLUSIONS A subset of OCCC cells are sensitive to PARP inhibition in vitro, which can be predicted by HR defects as defined by γH2AX/RAD51 foci formation. These results provide a rationale for the testing of HR deficiency and PARP inhibitors as a targeted therapy in a subset of OCCCs.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Gynecology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:24 January 2017
Deposited On:30 Jan 2017 10:14
Last Modified:21 Nov 2017 18:58
Publisher:Impact Journals, LLC
ISSN:1949-2553
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.18632/oncotarget.14011
PubMed ID:28002809

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