Cytotoxic and pro-oxidative effects of Imperata cylindrica aerial part ethyl acetate extract in colorectal cancer in vitro

详细信息    查看全文

• 作者：Amy Ho Yan Kwok ; Yan Wang ; Wing Shing Ho ; ^{ws203ho@cuhk.edu.hk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Imperata cylindrica ; Colorectal cancer ; Prostanoids ; Cytotoxicity ; Oxidative stress
• 刊名：Phytomedicine
• 出版年：2016
• 出版时间：15 May 2016
• 年：2016
• 卷：23
• 期：5
• 页码：558-565
• 全文大小：2612 K

文摘

Colorectal cancer (CRC) is the third most common cancer. Its global incidence and mortality have been on the rise. Recent strategy of therapies has involved the use of non-steroid anti-inflammatory drugs and cyclooxygenase-selective inhibitors. Aerial parts of Imperata cylindrical L. Raeusch (IMP) have been used as an anti-inflammatory agent in traditional Chinese medicine.

Hypothesis

Asarachidonate acid cascadeis often involved in inflammation-related malignancy and IMP is an anti-inflammatory agent, hence it is hypothesized that IMP aerial part ethyl acetate extract exerts cytotoxic effects on colorectal cancer cells in vitro.

Study design

The HT-29 adenocarcinoma cell line was used to elucidate its pro-apoptotic activities. Flow cytometry and fluorescent microscopy were performed to assess cell cycle arrest and the accumulation of reactive oxygen species (ROS). The mRNA and hormone levels of arachidonate acid pathways were studied via quantitative reverse transcription PCR (qRT-PCR) and ELISA.

Results

The 50% growth inhibitory effect (GI₅₀) of the IMP extract on HT-29 was measured with a value of 14.5 µg/ml. Immuno-blot and caspase-3/7 activity assay showed the pro-apoptotic effect of IMP on the activation of caspase cascade. G2/M arrest was observed via flow cytometry. The ROS activity was modulated by the IMP extraction a concentration-dependent manner in HT-29 cells. The IMP extract increased PGE₂ and PGF_2α levels qRT-PCR revealed that transcripts of rate-limiting PGE₂- and PGF_2α-biosynthetic enzymes – COX-1, mPGES1 and AKR1C3 were notably up-regulated. Among the prostanoid receptors, EP₁ and FP transcripts were up-regulated while EP₄ transcripts decreased. The findings suggest that the proliferative effect of PGE₂, which is generally believed to associate with heightened DNA synthesis and cross-talk with MAPK pathways, is likely triggered by the pro-apoptotic or -oxidative effects exerted by IMP extract in HT-29 cells. Concurring with this notion, indomethacin (COX-1/2-inhibitor) was demonstrated to potentiate the cytotoxic effect of IMP extract (GI₅₀ ≦ 10.8 µg/ml). The results show that the cytotoxic effect of IMP extract predominates over the influence of proliferative prostanoids released by challenged colorectal cancer cells, and may present a potential source for development of novel anti-cancer drugs.