Ornithine decarboxylase and phosphatase activity can be stimulated by low concentrations of interferon in human breast cancer cell lines.

The activity of the enzyme ornithine decarboxylase (ODC) is increased in confluent culture of two breast cancer cell lines (T47D and MCF-7) following a change of medium. The increase in activity is maximum at 12 hours and this level is reduced in cells treated with high concentrations of HuIFN-alpha. However, the increased level of ODC activity seen in the first few hours after medium change can be stimulated by low concentrations of interferon (10-100 units per ml). The activity of the acidic and alkaline phosphatase of the above cell lines are affected by HuIFN-alpha similar to ODC. In stimulating levels of ODC and phosphatases, interferon is acting similar to mitogens, and in T47D and MCF-7 cells this stimulatory effect precedes the inhibitory effect more commonly seen in interferon-treated cells.