Effects of delta9-tetrahydrocannabinol in Lewis lung adenocarcinoma cells in tissue culture.

We found a dose-related decrease in DNA synthesis in transformed cell cultures treated with delta9-tetrahydrocannabinol (delta9-THC). The decrease, observed over a 4-hour period, was not accompanied by a change in the radioactive precursor pool as compared to that of control culture. The distribution of labeled products clearly differed from that observed after treatment with cytosine arabinoside. delta9-THC inhibited DNA synthesis at some point beyond the uptake of 3H-thymidine.