beta-L-1,3-dioxolane-cytidine: A novel nucleoside that inhibits proliferation and induces differentiation of keratinocytes in vitro

beta-L-1,3-Dioxolane-cytidine (L-(-)-OddC) is a novel L-nucleoside, and its antitumor activity is under investigation in clinical trials. To evaluate the potential of L-(-)-OddC for treating hyperproliferative diseases of the skin, we examined its activity in human keratinocytes in vitro. The dose o f L-(-)-OddC that inhibited the rate of proliferation of keratinocytes by 5 0% was 50 nM. L-(-)-OddC was about as cytotoxic as 9-beta-D-arabinofuranosy lcytosine but was about 1,000 time more potent than 3'-azidothymidine. L-(- )-OddC caused irreversible growth arrest and induced differentiation of ker atinocytes. L-(-)-OddC altered morphology, increased the cell size of kerat inocytes and increased the expression of involucrin. These data suggest tha t L-(-)-OddC may have potential as a therapeutic agent against hyperprolife rative skin diseases.