Abstract 3780: Aven-mediated checkpoint kinase control regulates proliferation and resistance to chemotherapy in osteosarcoma cells

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Osteosarcoma is the most common primary bone malignancy with relatively high incidence in young people. Here, we found that expression of Aven was inversely correlated with metastasis-free survival in osteosarcoma patients and is increased in metastases compared to primary osteosarcoma biopsies. Also in chondrosarcoma, the second most common bone sarcoma, expression correlated with increased histological grade. Aven is an adaptor protein that has been implicated in anti-apoptotic signaling and serves as an oncoprotein in acute lymphoblastic leukemia. In human osteosarcoma cells, silencing Aven triggered a G2 cell cycle arrest. Chk1 protein levels were attenuated and ATR-Chk1 DNA damage response signaling in response to chemotherapy was abolished in Aven-depleted osteosarcoma cells while ATM, Chk2, and p53 activation remained intact. Osteosarcoma is notoriously difficult to treat with standard chemotherapy, and we examined whether pharmacological inhibition of the Aven-controlled ATR-Chk1 response could sensitize osteosarcoma cells to genotoxic compounds. Indeed, pharmacological inhibitors targeting Chk1/Chk2 or those selective for Chk1 synergized with standard chemotherapy in 2D cultures. Likewise, in 3D extracellular matrix-embedded cultures Chk1 inhibition effectively sensitized human osteosarcoma cells to chemotherapy. Together, these findings implicate Aven in ATR-Chk1 signaling and point towards Chk1 inhibition as a strategy to sensitize osteosarcomas to chemotherapy. Citation Format: Zuzanna Baranski, Tijmen T.H. Booij, Yvonne de Jong, Jolieke van Oosterwijk, Anne-Marie Cleton, Leo Price, Bob van de Water, Judith V.M.G. Bovee, Pancras C.W. Hogendoorn, Erik Danen. Aven-mediated checkpoint kinase control regulates proliferation and resistance to chemotherapy in osteosarcoma cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3780. doi:10.1158/1538-7445.AM2015-3780