We explored the in vitro and in vivo mechanism of antitumor action of the synthetic
flavonoid 2'-nitroflavone on LM3 murine mammary
adenocarcinoma cells. In vitro assays showed that
2'-nitroflavone increased the population of LM3 hypodiploid cells and produced a typical ladder of DNA fragmentation. Apoptotic cell death was also characterized by the activation of
caspase-8, -9 and -3, by an increment in the expression levels of the proapoptotic
protein Bax and by the release of
cytochrome c to cytosol. The in vivo effect of
2'-nitroflavone on
tumor growth was studied in BALB/c mice injected subcutaneously with LM3 cells. Results showed that
tumor volume and weight were significantly reduced at doses of 10 and 40 mg/kg of
2'-nitroflavone, respectively. Apoptotic cells were identified by TUNEL assay in
tumor slices from mice treated with 10 mg/kg of
2'-nitroflavone. Western blot analysis of
tumor lysate supernatants from treated mice revealed an upregulation of the total levels of Bax and
Fas receptor. In addition, administration of 40 mg/kg of
2'-nitroflavone to nontumor-bearing mice showed no histopathological effects on different organ tissues. This is the first report of the in vivo growth inhibitory effect of
2'-nitroflavone as an apoptotic agent likely useful for mammary
adenocarcinoma treatment.