Preclinical evaluation of olaparib and metformin combination in BRCA1 wildtype ovarian cancer


      • Anti-tumor effects of olaparib are enhanced by metformin in BRCA intact ovarian cancer cells in vitro and in vivo.
      • Olaparib activates AMPK in ovarian cancer cells.
      • This is a promising treatment regimen for women with epithelial ovarian cancer irrespective of BRCA status.



      BRCA mutated ovarian cancers show increased responsiveness to PARP inhibitors. PARP inhibitors target DNA repair and provide a second hit to BRCA mutated tumors, resulting in “synthetic lethality”. We investigated a combination of metformin and olaparib to provide “synthetic lethality” in BRCA intact ovarian cancer cells.


      Ovarian cancer cell lines (UWB1.289, UWB1.289.BRCA, SKOV3, OVCAR5, A2780 and C200) were treated with a combination of metformin and olaparib. Cell viability was assessed by MTT and colony formation assays. Flow cytometry was used to detect cell cycle events. In vivo studies were performed in SKOV3 or A2780 xenografts in nude mice. Animals were treated with single agent, metformin or olaparib or combination. Molecular downstream effects were examined by immunohistochemistry.


      Compared to single drug treatment, combination of olaparib and metformin resulted in significant reduction of cell proliferation and colony formation (p < 0.001) in ovarian cancer cells. This treatment was associated with a significant S-phase cell cycle arrest (p < 0.05). Combination of olaparib and metformin significantly inhibited SKOV3 and A2780 ovarian tumor xenografts which were accompanied with decreased Ki-index (p < 0.001). Metformin did not affect DNA damage signaling, while olaparib induced adenosine monophosphate activated kinase activation; that was further potentiated with metformin combination in vivo.


      Combining PARP inhibitors with metformin enhances its anti-proliferative activity in BRCA mutant ovarian cancer cells. Furthermore, the combination showed significant activity in BRCA intact cancer cells in vitro and in vivo. This is a promising treatment regimen for women with epithelial ovarian cancer irrespective of BRCA status.


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        • Foulkes W.D.
        Made-to-measure medicine: BRCA and gynaecological cancer.
        Lancet Oncol. 2014; 15: 783-785
        • Farmer H.
        • McCabe N.
        • Lord C.J.
        • Tutt A.N.
        • Johnson D.A.
        • Richardson T.B.
        • et al.
        Targeting the DNA repair defect in BRCA mutant cells as a therapeutic strategy.
        Nature. 2005; 434: 917-921
        • Haince J.F.
        • Rouleau M.
        • Hendzel M.J.
        • Masson J.Y.
        • Poirier G.G.
        Targeting poly(ADP-ribosyl)ation: a promising approach in cancer therapy.
        Trends Mol. Med. 2005; 11: 456-463
        • Musella A.
        • Marchetti C.
        • Gasparri M.L.
        • Salerno L.
        • Casorelli A.
        • Domenici L.
        • et al.
        PARP inhibition: a promising therapeutic target in ovarian cancer.
        Cell Mol. Biol. (Noisy-le-grand). 2015; 61: 44-61
        • Kim G.
        • Ison G.
        • McKee A.E.
        • Zhang H.
        • Tang S.
        • Gwise T.
        • et al.
        FDA approval summary: olaparib monotherapy in patients with deleterious germline BRCA-mutated advanced ovarian cancer treated with three or more lines of chemotherapy.
        Clin. Cancer Res. 2015; 21: 4257-4261
        • Konstantinopoulos P.A.
        • Wilson A.J.
        • Saskowski J.
        • Wass E.
        • Khabele D.
        Suberoylanilide hydroxamic acid (SAHA) enhances olaparib activity by targeting homologous recombination DNA repair in ovarian cancer.
        Gynecol. Oncol. 2014; 133: 599-606
        • Sui H.
        • Shi C.
        • Yan Z.
        • Li H.
        Combination of erlotinib and a PARP inhibitor inhibits growth of A2780 tumor xenografts due to increased autophagy.
        Drug Des Devel. Ther. 2015; 9: 3183-3190
        • Clark C.C.
        • Weitzel J.N.
        • O'Connor T.R.
        Enhancement of synthetic lethality via combinations of ABT-888, a PARP inhibitor, and carboplatin in vitro and in vivo using BRCA1 and BRCA2 isogenic models.
        Mol. Cancer Ther. 2012; 11: 1948-1958
        • Gotlieb W.H.
        • Saumet J.
        • Beauchamp M.C.
        • Gu J.
        • Lau S.
        • Pollak M.N.
        • et al.
        In vitro metformin anti-neoplastic activity in epithelial ovarian cancer.
        Gynecol. Oncol. 2008; 110: 246-250
        • Rattan R.
        • Graham R.P.
        • Maguire J.L.
        • Giri S.
        • Shridhar V.
        Metformin suppresses ovarian cancer growth and metastasis with enhancement of cisplatin cytotoxicity in vivo.
        Neoplasia. 2011; 13: 483-491
        • Lengyel E.
        • Litchfield L.M.
        • Mitra A.K.
        • Nieman K.M.
        • Mukherjee A.
        • Zhang Y.
        • et al.
        Metformin inhibits ovarian cancer growth and increases sensitivity to paclitaxel in mouse models.
        Am. J. Obstet. Gynecol. 2015; 212 (479 e1- e10)
        • Foretz M.
        • Guigas B.
        • Bertrand L.
        • Pollak M.
        • Viollet B.
        Metformin: from mechanisms of action to therapies.
        Cell Metab. 2014; 20: 953-966
        • Zhuang Y.
        • Miskimins W.K.
        Metformin induces both caspase-dependent and poly(ADP-ribose) polymerase-dependent cell death in breast cancer cells.
        Mol. Cancer Res. 2011; 9: 603-615
        • DelloRusso C.
        • Welcsh P.L.
        • Wang W.
        • Garcia R.L.
        • King M.C.
        • Swisher E.M.
        Functional characterization of a novel BRCA1-null ovarian cancer cell line in response to ionizing radiation.
        Mol. Cancer Res. 2007; 5: 35-45
        • Stordal B.
        • Timms K.
        • Farrelly A.
        • Gallagher D.
        • Busschots S.
        • Renaud M.
        • et al.
        BRCA1/2 mutation analysis in 41 ovarian cell lines reveals only one functionally deleterious BRCA1 mutation.
        Mol. Oncol. 2013; 7: 567-579
        • Rattan R.
        • Giri S.
        • Hartmann L.C.
        • Shridhar V.
        Metformin attenuates ovarian cancer cell growth in an AMP-kinase dispensable manner.
        J. Cell. Mol. Med. 2011; 15: 166-178
        • Hijaz M.
        • Das S.
        • Mert I.
        • Gupta A.
        • Al-Wahab Z.
        • Tebbe C.
        • et al.
        Folic acid tagged nanoceria as a novel therapeutic agent in ovarian cancer.
        BMC Cancer. 2016; 16: 220
        • Al-Wahab Z.
        • Mert I.
        • Tebbe C.
        • Chhina J.
        • Hijaz M.
        • Morris R.T.
        • et al.
        Metformin prevents aggressive ovarian cancer growth driven by high-energy diet: similarity with calorie restriction.
        Oncotarget. 2015; 6: 10908-10923
        • Al-Wahab Z.
        • Tebbe C.
        • Chhina J.
        • Dar S.A.
        • Morris R.T.
        • Ali-Fehmi R.
        • et al.
        Dietary energy balance modulates ovarian cancer progression and metastasis.
        Oncotarget. 2014; 5: 6063-6075
        • Kortmann U.
        • McAlpine J.N.
        • Xue H.
        • Guan J.
        • Ha G.
        • Tully S.
        • et al.
        Tumor growth inhibition by olaparib in BRCA2 germline-mutated patient-derived ovarian cancer tissue xenografts.
        Clin. Cancer Res. 2011; 17: 783-791
        • Tan D.S.
        • Kaye S.B.
        Chemotherapy for patients with BRCA1 and BRCA2-mutated ovarian cancer: same or different?.
        Am. Soc. Clin. Oncol. Educ Book. 2015; 114-21
        • Fong P.C.
        • Boss D.S.
        • Yap T.A.
        • Tutt A.
        • Wu P.
        • Mergui-Roelvink M.
        • et al.
        Inhibition of poly(ADP-ribose) polymerase in tumors from BRCA mutation carriers.
        N. Engl. J. Med. 2009; 361: 123-134
        • Fong P.C.
        • Yap T.A.
        • Boss D.S.
        • Carden C.P.
        • Mergui-Roelvink M.
        • Gourley C.
        • et al.
        Poly(ADP)-ribose polymerase inhibition: frequent durable responses in BRCA carrier ovarian cancer correlating with platinum-free interval.
        J. Clin. Oncol. 2010; 28: 2512-2519
        • Iglesias P.
        • Costoya J.A.
        The antimitotic potential of PARP inhibitors, an unexplored therapeutic alternative.
        Curr. Top. Med. Chem. 2014; 14: 2346-2365
        • Cai X.
        • Hu X.
        • Tan X.
        • Cheng W.
        • Wang Q.
        • Chen X.
        • et al.
        Metformin induced AMPK activation, G0/G1 phase cell cycle arrest and the inhibition of growth of esophageal squamous cell carcinomas in vitro and in vivo.
        PLoS One. 2015; 10e0133349
        • Del Conte G.
        • Sessa C.
        • von Moos R.
        • Vigano L.
        • Digena T.
        • Locatelli A.
        • et al.
        Phase I study of olaparib in combination with liposomal doxorubicin in patients with advanced solid tumours.
        Br. J. Cancer. 2014; 111: 651-659
        • Huehls A.M.
        • Wagner J.M.
        • Huntoon C.J.
        • Geng L.
        • Erlichman C.
        • Patel A.G.
        • et al.
        Poly(ADP-Ribose) polymerase inhibition synergizes with 5-fluorodeoxyuridine but not 5-fluorouracil in ovarian cancer cells.
        Cancer Res. 2011; 71: 4944-4954
        • Lee J.M.
        • Hays J.L.
        • Annunziata C.M.
        • Noonan A.M.
        • Minasian L.
        • Zujewski J.A.
        • et al.
        Phase I/Ib study of olaparib and carboplatin in BRCA1 or BRCA2 mutation-associated breast or ovarian cancer with biomarker analyses.
        J. Natl. Cancer Inst. 2014; 106: dju089
        • Beauchamp M.C.
        • Knafo A.
        • Yasmeen A.
        • Carboni J.M.
        • Gottardis M.M.
        • Pollak M.N.
        • et al.
        BMS-536924 sensitizes human epithelial ovarian cancer cells to the PARP inhibitor, 3-aminobenzamide.
        Gynecol. Oncol. 2009; 115: 193-198
        • Chen Y.
        • Zhang L.
        • Hao Q.
        Olaparib: a promising PARP inhibitor in ovarian cancer therapy.
        Arch. Gynecol. Obstet. 2013; 288: 367-374
        • Halicka H.D.
        • Zhao H.
        • Li J.
        • Traganos F.
        • Zhang S.
        • Lee M.
        • et al.
        Genome protective effect of metformin as revealed by reduced level of constitutive DNA damage signaling.
        Aging (Albany NY). 2011; 3: 1028-1038
        • Algire C.
        • Moiseeva O.
        • Deschenes-Simard X.
        • Amrein L.
        • Petruccelli L.
        • Birman E.
        • et al.
        Metformin reduces endogenous reactive oxygen species and associated DNA damage.
        Cancer Prev. Res. (Phila.). 2012; 5: 536-543
        • Ogrunc M.
        • Di Micco R.
        • Liontos M.
        • Bombardelli L.
        • Mione M.
        • Fumagalli M.
        • et al.
        Oncogene-induced reactive oxygen species fuel hyperproliferation and DNA damage response activation.
        Cell Death Differ. 2014; 21: 998-1012
        • Liu J.
        • Hou M.
        • Yuan T.
        • Yi G.
        • Zhang S.
        • Shao X.
        • et al.
        Enhanced cytotoxic effect of low doses of metformin combined with ionizing radiation on hepatoma cells via ATP deprivation and inhibition of DNA repair.
        Oncol. Rep. 2012; 28: 1406-1412
        • Fasih A.
        • Elbaz H.A.
        • Huttemann M.
        • Konski A.A.
        • Zielske S.P.
        Radiosensitization of pancreatic cancer cells by metformin through the AMPK pathway.
        Radiat. Res. 2014; 182: 50-59
        • Song C.W.
        • Lee H.
        • Dings R.P.
        • Williams B.
        • Powers J.
        • Santos T.D.
        • et al.
        Metformin kills and radiosensitizes cancer cells and preferentially kills cancer stem cells.
        Sci. Rep. 2012; 2: 362
        • Rattan R.
        • Ali Fehmi R.
        • Munkarah A.
        Metformin: an emerging new therapeutic option for targeting cancer stem cells and metastasis.
        J. Oncol. 2012; 2012: 928127
        • Magnard C.
        • Bachelier R.
        • Vincent A.
        • Jaquinod M.
        • Kieffer S.
        • Lenoir G.M.
        • et al.
        BRCA1 interacts with acetyl-CoA carboxylase through its tandem of BRCT domains.
        Oncogene. 2002; 21: 6729-6739
        • Walker J.W.
        • Jijon H.B.
        • Madsen K.L.
        AMP-activated protein kinase is a positive regulator of poly(ADP-ribose) polymerase.
        Biochem. Biophys. Res. Commun. 2006; 342: 336-341
        • Hardie D.G.
        AMPK–sensing energy while talking to other signaling pathways.
        Cell Metab. 2014; 20: 939-952