Apoptosis induction of colorectal cancer cells HTL-9 in vitro by the transformed products of soybean isoflavones by Ganoderma lucidum

Abstract

Soybean isoflavones have been one of the potential preventive candidates for antitumor research in recent years. In this paper, we first studied the transformation of soybean isoflavones with the homogenized slurry of Ganoderma lucidum. The resultant transformed products (TSI) contained (703.21±4.35) mg/g of genistein, with transformed rates of 96.63% and 87.82% of daidzein and genistein, respectively, and TSI also could enrich the bioactive metabolites of G. lucidum. The antitumor effects of TSI on human colorectal cancer cell line HTL-9, human breast cancer cell line MCF-7, and human immortalized gastric epithelial cell line GES-1 were also studied. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay showed that TSI could dramatically reduce the viability rates of HTL-9 cells and MCF-7 cells without detectable cytotoxicity on GES-1 normal cells when the TSI concentration was lower than 100 μg/ml. With 100 μg/ml of TSI, HTL-9 cells were arrested in the G1 phase, and late-apoptosis was primarily induced, accompanied with partial early-apoptosis. TSI could induce primarily earlyapoptosis by arresting cells in the G1 phase of MCF-7 cells. For HTL-9 cells, Western-blot and reverse-transcriptase polymerase chain reaction (RT-PCR) analysis showed that TSI (100 μg/ml) can up-regulate the expression of Bax, Caspase-3, Caspase-8, and cytochrome c (Cyto-c), indicating that TSI could induce cell apoptosis mainly through the mitochondrial pathway. In addition, the expression of p53 was up-regulated, while the expression of Survivin and nuclear factor κB (NF-κB) was down-regulated. All these results showed that TSI could induce apoptosis of HTL-9 cells by the regulation of multiple apoptosis-related genes.

中文概要

目的

通过灵芝菌生物转化大豆异黄酮,得到富含苷元及灵芝活性成分的多因子转化产物,并研究了转化产物对结直肠癌细胞HTL-9 的体外凋亡诱导,初步探讨转化产物的抗癌活性及机理。

创新点

灵芝是一种珍贵的药用真菌,大豆异黄酮的苷元物质也具有重要的药理活性,本文首次利用灵芝菌液体发酵的匀浆液生物转化大豆异黄酮,所得到的产物中大豆苷元与染料木素转化率高,同时还富集了灵芝菌的活性成分,并对转化产物的抗癌活性及机理进行了初步探讨。

方法

首先利用灵芝菌液体发酵的匀浆体系生物转化大豆异黄酮(图1)。其次,对转化产物的抗癌活性进行研究,主要包括对癌细胞存活率(图2)、细胞凋亡(图3)及细胞周期分布(图4)的影响。最后,利用蛋白质印迹(Western-blot)与逆转录聚合酶链反应(RT-PCR)技术对凋亡相关的基因和蛋白进行检测(图5 和表2),初步探讨转化产物的体外抗癌机理。

结论

本实验结果显示,转化产物中大豆苷元及染料木素的转化率分别为96.63%和87.82%,其中染料木素的含量可达(703.21±4.35) mg/g,同时转化产物中还富含了灵芝菌的活性成分。其次,对转化产物抗癌活性研究发现,其能有效降低HTL-9 细胞的存活率,可通过将细胞阻滞于G1 期而诱导细胞晚期凋亡。此外,转化产物(100 μg/ml)还可明显上调Bax、Caspase-3、Caspase-8、Cyto-c和p53 的表达量,而Survivin 和NF-κB 表达量发生明显下调。结果表明,转化产物主要通过线粒体途径诱导细胞凋亡,但同时还调控多个与凋亡相关的基因。