Inhibitory Effect of the Branch Extracts from Taxillus yadoriki Parasitic to Neolitsea sericea against the Cell Proliferation in Human Lung Cancer Cells, A549

참식나무(Neolitsea sericea) 기주 참나무겨우살이(Taxillus yadoriki) 가지 추출물의 폐암세포 A549에 대한 세포생육 억제활성

Abstract

In this study, we evaluated the anti-cancer activity and potential molecular mechanism of 70% ethanol extracts of branches from Taxillus yadoriki parasitic to Neolitsea sericea (TN-NS-B) against human lung cancer cells, A549. TY-NS-B dose-dependently suppressed the growth of A549 cells. TY-NS-B decreased ${\beta}$-catenin protein level, but not mRNA level in A549 cells. The downregulation of ${\beta}$-catenin protein level by TY-NS-B was attenuated in the presence of MG132. Although TY-NS-B phosphorylated ${\beta}$-catenin protein, the inhibition of $GSK3{\beta}$ by LiCl did not blocked the reduction of ${\beta}$-catenin by TY-NS-B. In addition, TY-NS-B decreased ${\beta}$-catenin protein in A549 cells transfected with Flag-tagged wild type ${\beta}$-catenin or Flag-tagged S33/S37/T41 mutant ${\beta}$-catenin construct. Our results suggested that TN-NS-B may downregulate ${\beta}$-catenin protein level independent on $GSK3{\beta}$-induced ${\beta}$-catenin phosphorylation. Based on these findings, TY-NS-B may be a potential candidate for the development of chemopreventive or therapeutic agents for human lung cancer.

이상의 연구 결과로 미루어 볼 때, 참식나무 기주 참나무겨우살이(TY-NS-B)는 $GSK3{\beta}$에 의한 ${\beta}$-catenin 인산화에 의존하지 않는 ${\beta}$-catenin의 분해 유도를 통해 암세포의 생육과 관련된 c-Myc의 발현을 억제하며, 이것은 비소세포성 폐암의 생육억제와 관련이 있는 것으로 판단된다. 또한, 본 결과는 항암을 위한 대체보완소재로 참식나무 기주 참나무겨우살이의 활용이 가능할 것으로 판단된다. 그러나 추가적 연구를 통해 참식나무 기주 참나무겨우살이가 어떻게 ${\beta}$-catenin의 분해 유도에 관여하는지에 대한 기전연구와 관련 활성물질의 분석연구가 필요할 것으로 사료된다.

Fig. 1. Effect of TY-NS-B on the cell growth and β-catenin expression in human lung cancer cells, A549. (A) Cell growth was evaluated by MTT assay at 24 h after TY-NS-B treatment. *p < 0.05 compared to cell without TY-NS-B. (B) A549 cells were treated with TY-NS-B at the indicated concentrations for 24 h. Western blot analysis was performed against β-catenin. Actin was used as internal control. (C) A549 cells were treated with TY-NS-B (25 ㎍/mL) for the indicated times. Western blot analysis was performed against β-catenin. Actin was used as internal control. (D) RT-PCR analysis of β-catenin and c-Myc gene expression was performed at 24 h after TY-NS-B treatment.

Fig. 2. Effect of TY-NS-B on β-catenin proteasomal degradation in human lung cancer cells, A549. (A) A549 cells were pretreat with 20 μM of MG132 for 2 h and then co-treated with TY-NS-B for 10 h. (B) A549 cells were treated with TY-NS-B for the indicated times (C) A549 cells were pretreat with 20 mM of LiCl for 2 h and then co-treated with TY-NS-B for 10 h. (D) A549 cells were transfected with Flag-tagged wild type β-catenin or Flag-tagged S33/S37/T41 mutant β-catenin construct for 48 h and the co-treated with TY-NS-B for 12 h. Western blot analysis was performed against β-catenin. Actin was used as internal control.

Table 1. Sequence of oligonucleotide primers used for RT-PCR