Growth arrest and induction of apoptosis in high-risk leukemia cells by strawberry components in vitro

Strawberries (Fragaria x ananassa) contain phytochemicals that have anti-inflammatory and anti-cancer activity. We investigated the ability of purified strawberry fractions to induce apoptotic cell death in pre-B acute lymphoblastic leukemia (ALL) lines, including lines derived from patients with high-risk B-ALL carrying the t(4;11)(q21;q23) chromosomal translocation. The isolated strawberry constituents were first screened for their anti-cancer activity using a 24 h fluorescence microplate method for detecting mitochondrial membrane depolarization. Active samples were further investigated for induction of apoptosis after addition of multiple doses to the leukemia cells over a period of 72 h. Quercetin, kaempferol, and ellagic acid induced significant apoptosis in the three cancer cell lines, as measured by loss of nuclear DNA, loss of mitochondrial membrane potential, and activation of caspase-3. Our data show that constituents of strawberries induce apoptosis in high-risk leukemia cells and may have potential in the prevention or treatment of this disease.