Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand.
Biol Res. 2012;45(1):45-50. doi: 10.4067/S0716-97602012000100006.
Sericin is a silk protein woven from silkworm cocoons (Bombyx mori). In animal model, sericin has been reported to have anti-tumoral action against colon cancer. The mechanisms underlying the activity of sericin against cancer cells are not fully understood. The present study investigated the effects of sericin on human colorectal cancer SW480 cells compared to normal colonic mucosal FHC cells. Since the size of the sericin protein may be important for its activity, two ranges of molecular weight were tested. Sericin was found to decrease SW480 and FHC cell viability. The small sericin had higher anti-proliferative effects than that of the large sericin in both cell types. Increased apoptosis of SW480 cells is associated with increased caspase-3 activity and decreased Bcl-2 expression. The anti-proliferative effect of sericin was accompanied by cell cycle arrest at the S phase. Thus, sericin reduced SW480 cell viability by inducing cell apoptosis via caspase-3 activation and down-regulation of Bcl-2 expression. The present study provides scientific data that support the protective effect of silk sericin against cancer cells of the colon and suggests that this protein may have significant health benefits and could potentially be developed as a dietary supplement for colon cancer prevention.
丝胶是一种由蚕茧（Bombyx mori）织成的丝蛋白。在动物模型中，已报道丝胶对结肠癌具有抗肿瘤作用。丝胶对癌细胞活性的作用机制尚未完全阐明。本研究比较了丝胶对人结直肠癌细胞 SW480 与正常结肠黏膜 FHC 细胞的影响。由于丝胶蛋白的大小可能对其活性很重要，因此测试了两种分子量范围。结果发现丝胶降低了 SW480 和 FHC 细胞的活力。小分子量丝胶在两种细胞类型中的增殖抑制作用均高于大分子量丝胶。SW480 细胞凋亡增加与 caspase-3 活性增加和 Bcl-2 表达减少有关。丝胶的增殖抑制作用伴随着细胞周期在 S 期停滞。因此，丝胶通过激活 caspase-3 和下调 Bcl-2 表达诱导细胞凋亡，从而降低 SW480 细胞活力。本研究提供了科学数据，支持丝胶对结肠癌细胞的保护作用，并表明这种蛋白质可能具有重要的健康益处，并有可能开发为结肠癌预防的膳食补充剂。
