Abstract

The effects of two flavones (baicalein, chrysin) and two flavonols (galangin, kaempferol) on induction of differentiation in a human esophageal squamous cell carcinoma (KYSE-510) cell line were investigated in this study. Four compounds were found to be able to inhibit proliferation of KYSE-510 cells in a dose- and time-dependent manner. The inhibitory potency of them on the growth of KYSE-510 cells was in the order of galangin > chrysin > baicalein >kaempferol. The KYSE-510 cells treated with these compounds for 24 h showed differentiation characteristics including the differentiation-specific morphological changes, the augmentation of differentiation markers and the inhibition of human telomerase reverse transcriptase. The potency of these compounds on induction of differentiation was similar to that of them on growth inhibition. To elucidate the possible mechanisms by which these compounds modulate proliferation and differentiation in KYSE-510 cells, the alterations of three genes (p21^waf1, cyclin B1 and D1) related to proliferation and differentiation were investigated by real-time RT-PCR and Western blot. The results showed that the up-regulation of p21^waf1 and down-regulation of cyclin B1 and D1 at the mRNA and protein levels in KYSE-510 cells treated with four compounds were observed, which implied that p21^waf1, cyclin B1 and D1 might be target genes of these compounds in inducing differentiation.

Key words: Flavones, flavonols, differentiation, esophageal cancer.

Abbreviation

BSA, Bovine serum albumin; DMSO, dimethyl sulfoxide; EB, ethidium bromide; EDTA, ethylenediaminetetraacetic acid; FBS, fetal bovine serum; FITC, fluorescein isothiocyanate; 5-FU, 5-fluorouracil; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide; PBS, phosphate- buffered saline; PI, propidium iodide; PMSF,phenylmethyl sulfonylfluoride; RNase, ribonuclease sodium dodesyl sulfate–polyacrylamide gel; TBS, tris buffered saline.