541 The abnormal bone remodeling associated with prostate cancer bone metastasis is attenuated by TAS-115, the dual inhibitor for HGF/VEGF signaling

Results: As expected, vemurafenib induced a concentration-dependent reduction in P-MEK1/2 and P-ERK1/2 levels, consistent with signaling pathway inhibition. There was a concomitant fall in extracellular lactate (down to 70±11% of controls, p = 0.01) that coincided with reduced hexokinase-II expression, indicative of decreased glycolytic activity. Analysis of C-labelled intracellular intermediates formed from [1-C] glucose revealed a reduction in [3-C] lactate (to 47±14% of controls, p = 0.002) coupled with a build-up of intracellular [1-C] glucose (up to 240±42%, p = 0.004) and [2,3-C] glutamate up to 157±26% (p = 0.02-pyruvate carboxylase activity) while [4-C] glutamate (pyruvate dehydrogenase activity) remained unchanged (101±20% of controls). These effects are consistent with reduced utilization of glucose as well as its preferential routing to the TCA cycle via pyruvate carboxylase. Conclusions: Our data show that BRAF inhibition with vemurafenib alters glucose utilization in BRAF mutant human melanoma cells in favour of TCA cycle metabolism. Further work is required to establish the significance of this metabolic shift and the potential to exploit it for improving therapeutic activity.