YD15 설암 세포에 대한 quercetin의 작용기전 연구

Abstract

Quercetin, one of flavonol compounds with anti-oxidant and anti-inflammatory properties, has been shown anti-carcinogenic activities on various cancer cell types. In this study, we investigated the cellular effects of quercetin on YD15 tongue carcinoma cells. In an MTT data quercetin was cytotoxic on YD15 cells and quercetin strongly inhibited the proliferation of YD15 cells. The inhibition of cell proliferation was accompanied by cell cycle arrest at S phase and/or G2/M phase and apoptosis with increased cell population at sub-G1, depending on time and dose of quercetin. Quercetin dramatically inhibited the expression of several cell cycle proteins such as cyclin D1, cycline B1 and cdk4 at high dose and slightly inhibited the expression of cyclin E1, cdk1. Quercetin-induced p21 expression was maximized at 10 µg/ml and reduced at higher dose (> 10 µg/ml). Quercetin decreased procaspase 3 with the concomitant activation of caspase 7 and cleaved PARP. The level of cleaved caspase 7 and PARP was maximized at 10 µg/ml of quercetin. Interestingly, the expression of Bcl-2 family proteins was not affected by quercetin treatment. Instead, aberrant multipolar mitotic spindle was induced at 10 µg/ml. This was accompanied by centrosome supernumerary / declustering and the increased frequency of multinucleated cells. The multipolar mitotic spindles with supernumerary / declustered centrosomes, induced by 10 µg/ml quercetin, were disappeared with the formation of pseudo-bipolar mitotic spindle (with pseudo-two centrosomes) when quercetin was removed supporting that quercetin induced multipolar mitosis leading to cell cycle arrest, and mitotic catastrophe causing cell death by apoptosis. Quercetin also induced senescence. The positive staining of senescence-associated beta galactosidase (SA-βgal) and the suppression of Lamin B1 expression at both mRNA and protein confirmed that quercetin induced senescence on YD15 cells. Finally, quercetin suppressed AKT phosphorylation while increasing ERK phosphorylation. Reduced AKT phosphorylation might be involved in the inhibition of cell proliferation. Taken together, our data supports that quercetin suppressed the proliferation of YD15 cells through the mitotic catastrophe and the induction of senescence.