College of Animal Sciences, Zhejiang University, Hangzhou 310058, China.
Int J Mol Sci. 2018 Mar 28;19(4):1013. doi: 10.3390/ijms19041013.
Silkworm pupae () are a high-protein nutrition source consumed in China since more than 2 thousand years ago. Recent studies revealed that silkworm pupae have therapeutic benefits to treat many diseases. However, the ability of the compounds of silkworm pupae to inhibit tumourigenesis remains to be elucidated. Here, we separated the protein of silkworm pupae and performed alcalase hydrolysis. Silkworm pupa protein hydrolysate (SPPH) can specifically inhibit the proliferation and provoke abnormal morphologic features of human gastric cancer cells SGC-7901 in a dose- and time-dependent manner. Moreover, flow cytometry indicated that SPPH can induce apoptosis and arrest the cell-cycle in S phase. Furthermore, SPPH was shown to provoke accumulation of reactive oxygen species (ROS) and depolarization of mitochondrial membrane potential. Western blotting analysis indicated that SPPH inhibited Bcl-2 expression and promoted Bax expression, and subsequently induced apoptosis-inducing factor and cytochrome C release, which led to the activation of initiator caspase-9 and executioner caspase-3, cleavage of poly (ADP-ribose) polymerase (PARP), eventually caused cell apoptosis. Moreover, SPPH-induced S-phase arrest was mediated by up-regulating the expression of E2F1 and down-regulating those of cyclin E, CDK2 and cyclin A2. Transcriptome sequencing and gene set enrichment analysis (GSEA) also revealed that SPPH treatment could affect gene expression and pathway regulation related to tumourigenesis, apoptosis and cell cycle. In summary, our results suggest that SPPH could specifically suppress cell growth of SGC-7901 through an intrinsic apoptotic pathway, ROS accumulation and cell cycle arrest, and silkworm pupae have a potential to become a source of anticancer agents in the future.
蚕蛹（）是中国两千多年来食用的高蛋白营养源。最近的研究表明，蚕蛹具有治疗多种疾病的功效。然而，蚕蛹化合物抑制肿瘤发生的能力仍有待阐明。在这里，我们分离了蚕蛹的蛋白质并进行了碱性蛋白酶水解。蚕蛹蛋白水解物（SPPH）可以特异性地抑制人胃癌细胞 SGC-7901 的增殖，并在剂量和时间依赖性方式下引起异常的形态特征。此外，流式细胞术表明 SPPH 可以诱导细胞凋亡并将细胞周期阻滞在 S 期。此外，SPPH 被证明可以引起活性氧（ROS）的积累和线粒体膜电位的去极化。Western blot 分析表明，SPPH 抑制 Bcl-2 的表达并促进 Bax 的表达，随后诱导凋亡诱导因子和细胞色素 C 的释放，导致起始半胱天冬酶-9 和执行半胱天冬酶-3 的激活，多聚（ADP-核糖）聚合酶（PARP）的裂解，最终导致细胞凋亡。此外，SPPH 诱导的 S 期阻滞是通过上调 E2F1 的表达和下调细胞周期蛋白 E、CDK2 和细胞周期蛋白 A2 的表达来介导的。转录组测序和基因集富集分析（GSEA）也表明，SPPH 处理可以影响与肿瘤发生、细胞凋亡和细胞周期相关的基因表达和途径调节。总之，我们的结果表明，SPPH 可以通过内在的凋亡途径、ROS 积累和细胞周期阻滞特异性地抑制 SGC-7901 细胞的生长，蚕蛹未来有可能成为抗癌药物的来源。
