Statins inhibit proliferation and cytotoxicity of a human leukemic natural killer cell line

BACKGROUND: Natural killer cells comprise the body’s first line of defense against virus-infected cells. As is true of all lymphocytes, natural killer cell malignancies can develop, however natural killer cell leukemias can be very difficult to treat due to their intrinsic resistance to chemotherapeutic agents. With the recent understanding that statin drugs may have anti-cancer properties, our investigations have focused on the ability of statins to inhibit the growth and cytotoxicity of the YT-INDY natural killer cell leukemia cell line. RESULTS: Our findings indicate that several statin compounds can inhibit YT-INDY proliferation disrupt cell cycle progression and abrogate natural killer cell cytotoxicity. Since natural killer cell leukemia cytotoxicity may play a role in the pulmonary damage seen in these patients, this is an important finding. Cytotoxicity, proliferation and cell cycle progression could be restored by the addition of mevalonate, signifying that the statin effects are brought about through HMG CoA reductase inhibition. The mevalonate pathway intermediate geranylgeranyl pyrophosphate, but not other intermediates in the mevalonate pathway, partially reversed statin-induced inhibition of YT-INDY proliferation and cytotoxicity. These results suggest that blockage of products made in the latter part of the mevalonate pathway may account for the observed inhibitory effects on YT-INDY proliferation and cytotoxicity. However, geranylgeranyl pyrophosphate could not reverse the statin-induced inhibition of the cell cycle. CONCLUSIONS: These results suggest that the statin drugs should be investigated as a potential therapeutic strategy for human natural killer cell leukemias possibly in combination with chemotherapeutic agents.