Low concentration of formononetin stimulates the proliferation of nasopharyngeal carcinoma cell line CNE2 by upregulating bcl-2 and p-ERK1/2 expression

Abstract

Context Formononetin is a typical phytoestrogen, which is a bioactive component found in red clover plants. Previous studies have shown that formononetin inhibits the proliferation of several types of cancer cells, including prostate cancer and osteosarcoma. However, how formononetin affects the proliferation of CNE2 is not clear.Objective The objective of this study is to investigate the effects of formononetin on nasopharyngeal carcinoma cells in vitro, along with the underlying mechanism.Materials and methods CNE2 cells were incubated with various concentrations of formononetin (0, 0.1, 0.2, 0.3 and 1 μM) for 48 h. Cell proliferation was measured by [3-(4,5-dimethylthiazol-2-yl)]-2,5-diphenyltetrazolium bromide (MTT) assay, while the rate of apoptosis was measured by flow cytometry. Bcl-2 and bax mRNA expression levels were determined by real time polymerase chain reaction (RT-PCR), while p-ERK1/2 and bcl-2 protein expression levels were quantified by Western blotting.Results Formononetin promoted the proliferation of CNE2 cells at low concentrations (0, 0.05, 0.1, 0.2, 0.5, 1, 2 and 5 μM), OD values increased from 0.27 ± 0.01 to 0.30 ± 0.01, 0.30 ± 0.01,0.36 ± 0.01, 0.35 ± 0.01, 0.34 ± 0.01, 0.34 ± 0.01 and 0.32 ± 0.01, respectively. The percentage of late apoptosis declined from 6.77% ± 0.73% (0 μM group) to 6.2% ± 0.4% (0.1 μM group), 3.83% ± 0.71% (0.3 μM group) and 5.1% ± 0.52% (1M group). The mRNA levels of bax and bcl-2 were down- and upregulated, respectively, by formononetin. Bcl-2 and p-ERK1/2 protein levels were also upregulated.Conclusions Formononetin stimulates CNE2 cell proliferation and has an inhibitory effect on CNE2 cells apoptosis, which is mediated by the activation of the ERK1/2 signaling pathways.