The sensitivity of HeLa and Chinese hamster (ovary) cells to methylene dimethane sulphonate.

HeLa and Chinese hamster (ovary) cells were exposed in vitro to methylene dimethanesulphonate (MDMS) and their survival of colony-forming ability was assayed in monolayer culture. Asynchronous cultures were exposed to the drug for the whole culture period but cell survival was complicated by the toxicity of formaldehyde which is a final breakdown product of the drug. A short treatment schedule of 15 min within the hydrolytic half life of the agent was therefore employed and the response of synchronous cultures of HeLa cells was then assayed throughout the course of the cells cycle. Cells were most sensitive at the beginning of the DNA synthetic phase (early-S) and most resistant at the end (late-S).