Flavonoid-enriched extracts from Nelumbo nucifera leaves inhibits proliferation of breast cancer in vitro and in vivo

Aim of the study: This study was aimed to investigate the antitumor effect of Nelumbo nucifera Leaf extract (NLE) on human MCF-7 cell line in vitro and in vivo. Materials and methods: Qualitative analysis showed that NLE contained several compounds, including polyphenols, based on high-performance liquid chromatography (HPLC) analysis. We utilized flow cytometry, Western blot analysis, and immunoprecipitation assays to explore the inhibitory effect of NLE on MCF-7 human breast cancer cells. Furthermore, the tumoricidal effect of NLE was further measured using a xenograft nude mouse model. Results: The polyphenols identified in NLE consisted primarily of gallic acid, rutin, and quercetin. Cell-cycle analysis revealed that MCF-7 cells treated with NLE were arrested at the G0/G1 phase (approximately 86.54%). With western blotting, we found that treatment with NLE particularly induced p53 phosphorylation and p21 expression, and down-regulated expression of cyclins and cdks, which was responsible for the high protein expression of RB/E2F. Inactivation of fatty acid synthase (FAS) implied that FAS was a potent regulator as well of NLE-mediated anti-carcinogenesis. In our in vivo analysis, treatment with NLE (0.5 and 1%) effectively reduced tumor volume and tumor weight in mice inoculated with MCF-7 cells compared to the control samples. Conclusions: These results confirmed that cell-cycle arrest was sufficient to elicit tumor regression following NLE treatment. Overall, our studies indicated that NLE has an antitumor activity and significant potential as a chemotherapeutic agent.