N6‐isopentenyladenosine: A potential therapeutic agent for a variety of epithelial cancers

Isopentenyladenosine (i 6 A) is a product of isopentenyltransferases and, in mammals, occurs either bound to tRNA or as a free nucleoside. Sporadic reports have suggested an anticancer effect of i 6 A, mostly on leukemia cells. The present analysis of 9 human epithelial cancer cell lines derived from different types of malignant tissue revealed complete suppression of clonogenic activity in 8 of the lines after exposure to i 6 A at a concentration of 10 μM. Mechanistic studies showed that i 6 A tumor suppressor activity is associated with inhibition of cell proliferation, a block in DNA synthesis and morphological changes. These results point to i 6 A and to its possible derivatives as a new potential class of wide‐spectrum anticancer agents. © 2007 Wiley‐Liss, Inc.