Validation of Src Family Kinases (SFKs) and phosphatidylinositol 3-kinases (PI-3Ks) asDrug Targets in Osteosarcoma

Abstract

inhibitors of Src family protein kinases (SFKs) and phosphatidylinositol 3-kinases (PI-3K) are in early clinical trials for adult cancers. Whilst Src is rarely mutated in human tumours, Src levels and kinase activity are elevated and increase with tumour progression in a range of human tumour types including osteosarcoma. Constitutively active PI-3K signalling activity is a common feature of paediatric sarcomas. The aim of this study was to investigate the importance of SFKs and PI-3Ks in survival, proliferation, invasion and motility in a paediatric sarcoma tumour type, osteosarcoma, and to test the hypothesis that combined inhibition of SFKs and PI-3K would benefit osteosarcoma patients. To test this hypothesis, human osteosarcoma cells were used in in vitro and in vivo preclinical models of the disease. 3 osteosarcoma cell lines were selected from a panel of 6 for further study. Incubation with greater than or equal to 0.1μM saracatinib for 24h inhibited SFK signalling as measured by a decrease in the phosphorylation of downstream targets FAK and paxillin in both cell lines. Similarly, inhibition of PI-3K signalling with greater than or equal to 0.1 μM PI-103 reduced levels of p-AKT and p-PRAS40. Concentrations up to 10 μM saracatinib or 10 μM PI-103 did not induce apoptosis. Concentrations up to 10 μM, saracatinib had no effect on proliferation whilst PI-103 was anti-proliferative in both cell lines, causing pronounced G1 phase cell cycle arrest. Both saracatinib and PI-103 inhibited motility at clinically achievable concentrations using a wound healing assay. Both saracatinib and PI-103 inhibited invasion at clinically achievable concentrations, through an 8 micron pore membrane. A combination of 1 μM saracatinib and 1 μM PI-103 was significantly more effective at inhibiting motility (p=

Date of Award	1 Aug 2013
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Caroline Dive (Supervisor) & Guy Makin (Supervisor)