C92
The effect of thymidine phosphorylase on tumour growth
Natasha Wind1, Mark Maconochie2, Brian Telfer1, Philip Reigan1, Sally Freeman1, Kaye Williams1, Ian Stratford1
1University of Manchester, Manchester, UK, 2University of Sussex, Brighton, UK
Background
Thymidine Phosphorylase (TP) displays chemotactic activity in vitro and angiogenic activity in vivo.
Aims
The effect of TP on cell and tumour growth was investigated using a number of murine embryonic fibroblast (MEF) cells that are either wild type, heterozygous or null for TP and cancer cell lines RT112 wt, empty vector (EV11) and TP over-expressing (2T10).
Results
In vitro growth rates of MEFs were identical in air but in anoxia the -/- cell growth reduced after 5 days unlike wt and +/- which continued to proliferate. A significant increase in TP activity with prolonged exposure to anoxia was observed in wt p=0.04 Activity in air was low in all cells. Expression levels determined by Western blot were low in all cell lines bar 2T10s that showed marked over-expression. When established as tumours the 2T10 cells grew more aggressively than EV11 or wt cells and a larger number of blood vessels observed in comparison with the others, EV11=10, RT112=17, 2T10=30 (average vessel count in 5 fields of view, 100x magnification), showing that TP relays an aggressive phenotype in vivo and the need for new cancer therapies. Novel inhibitors of TP were screened against lysates prepared from 2T10s. One inhibitor was found to be 10 fold more potent than current lead compound, inhibiting TP activity at 0.01µM compared with TPI at 0.1µM.
Conclusion
TP appears to have some impact on tumour growth, tumours that over-express the enzyme are more aggressive therefore the availability of new inhibitors could be very beneficial in targeting these tumours.
