Effects of silk sericin on the proliferation and apoptosis of colon cancer cells

Abstract

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 scientifi c data that support the protective effect of silk sericin against cancer cells of the colon and suggests that this protein may have signifi cant health benefi ts and could potentially be developed as a dietary supplement for colon cancer prevention.

Silkworm Sericin: Properties and Biomedical Applications

“…Kaewkorn et al [73] studied the effect of sericin in the proliferation and apoptosis of colon tumour cells. The small-size sericin, 61–132 kDa, showed an inhibitory effect on human colorectal cancer cells (SW480) when compared to normal human fetal colonic mucosal cells (FHC).…”

Dose-related effects of sericin on preadipocyte behavior within collagen/sericin hybrid scaffolds

“…Thus, it has been proved to have important antibacterial and ultraviolet (UV) resistance properties [26], as well as excellent antioxidant, anti-apoptotic and antiinflammatory potentials [27,28]. Furthermore, sericin has also been reported to suppress in vitro lipid peroxidation [29] and to display anti-tumor properties [30,31]. In serum-free cultures, this protein was shown to enhance proliferation and attachment of mammalian cell lines including hybridoma cells [32].…”

The effect of dietary sericin on rats

“…Sericin has previously been shown to have anti-tumour effect, particularly in colon cancers [3][4][5] . Sericin may enhance systemic immunity implicated in elimination of tumour cells.…”

“…This protein consists of a group of polypeptides with molecular mass ranging from 20-400 kDa. Pharmacological activities of sericin includes anti-oxidant 1 , anti-coagulant 2 , anti-cancer activities [3][4][5] , tyrosinase inhibition 6 , liver and gastric protection 7,8 , as well as cholesterol lowering 9,10 . Sericin promotes wound healing process without causing inflammation 11 and is widely used in tissue engineering 12,13 .…”