For example, although some melanoma cells will switch into an automatic death mode when restricted, normal cells do not. Since tumors are collections of cells with differing abilities to metastasize, it is possible that the dietary restrictions primarily target those that do it well. Restriction, for example, may change a cell s ability to make or secrete some of the proteins it needs in order to metastasize, says Meadows. Once I establish how the dietary restriction reduces metastasis, it will be easier to target those mechanisms and develop better, more specific therapies, says Meadows. Similar tactics have been used in treatments for other cancers.
Leukemia cells can t survive without asparagine, another amino acid.
Chemotherapy targeting asparagine is part of the standard repertoire of leukemia treatments. In fact, Meadows work on the effect of amino acid restrictions on cancer began while he was in graduate school, where he worked with the scientists who helped develop the leukemia treatments. Since that time, his work has evolved to include the question of whether other cancers might also have specific and different amino acid requirements. He initially investigated the effect of dietary restrictions on tumor growth but soon switched to the effect on metastasis. The spread of a melanoma, or of cancers in general, has more clinical relevance, says Meadows.