Flavonoids Inhibit Cell Growth and Induce Apoptosis in B16 Melanoma 4A5 Cells

Abstract

We investigated the growth inhibitory activity of several flavonoids, including apigenin, luteolin, kaempherol, quercetin, butein, isoliquiritigenin, naringenin, genistein, and daizein against B16 mouse melanoma 4A5 cells. Isoliquiritigenin and butein, belonging to the chalcone group, markedly suppressed the growth of B16 melanoma cells and induced cell death. The other flavonoids tested showed little growth inhibitory activity and scarcely caused cell death. In cells treated with isoliquiritigenin or butein, condensation of nuclei and fragmentation of nuclear DNA, which are typical phenomena of apoptosis, were observed by Hoechst 33258 staining and by agarose gel electrophoresis of DNA. Flowcytometric analysis showed that isoliquiritigenin and butein increased the proportion of hypodiploid cells in the population of B16 melanoma cells. These results demonstrate that isoliquiritigenin and butein inhibit cell proliferation and induce apoptosis in B16 melanoma cells. Extracellular glucose decreased the proportion of hypodiploid cells that appeared as a result of isoliquiritigenin treatment. p53 was not detected in cells treated with either of these chalcones, however, protein of the Bcl-2 family were detected. The level of expression of Bax in cells treated with either of these chalcones was markedly elevated and the level of Bcl-XL decreased slightly. Isoliquiritigenin did not affect Bcl-2 expression, but butein down-regulated Bcl-2 expression. From these results, it seems that the pathway by which the chalcones induce apoptosis may be independent of p53 and dependent on proteins of the Bcl-2 family. It was supposed that isoliquiritigenin induces apoptosis in B16 cells by a mechanism involving inhibition of glucose transmembrane transport and promotion of Bax expression. On the other hand, it was suggested that butein induces apoptosis via down-regulation of Bcl-2 expression and promotion of Bax expression. This mechanism differs from the isoliquiritigenin induction pathway.

Evaluation of anti–apoptotic activity of different dietary antioxidants in renal cell carcinoma against hydrogen peroxide

“…Although the role of apoptosis in pathological situation for cancer suppression has been already evaluated [9][10][11] . This study demonstrates that antioxidants have the potential scavenging effect on intracellular oxidative damage directly induced by H 2 O 2 which, in turn, lead to an improvement in the percentage cell viability.…”

“…Apoptosis, in association with oxidative stress, is an active cell death mechanism, which occurs during several pathological situations for cancer suppression [9][10][11] . It can be induced by two different pathways, the deathreceptor pathway and mitochondrial pathway (mediated by caspase-8 and caspase-9, respectively).…”

Apigenin and cancer chemoprevention: Progress, potential and promise (Review)

“…Apigenin has also been shown to induce WAF1/p21 levels resulting in cell cycle arrest and apoptosis in androgen-responsive human prostate cancer, LNCaP cells and androgen-refractory DU145 cells, regardless of the Rb status and p53-dependence or p53 independence (52,53). In addition, apigenin has been shown to induce apoptosis in a wide range of malignant cells (54)(55)(56). Apigenin treatment has been shown to alter the Bax/Bcl-2 ratio in favor of apoptosis, associated with release of cytochrome c and induction of Apaf-1, which leads to caspase activation and PARP-cleavage (53).…”

In Vitro-Screening for Cancer-Suppressive Effect of Food Components

“…Therefore, the inhibition of cancer cell growth and the induction of apoptotic cancer cell death are important mechanisms of cancer prevention. Apoptosis is one of the major mechanisms of cancer suppression 5,7,10 . The apoptotic cells are fragmented and removed by phagocytosis.…”