Mitogenic effect of sericin on mammalian cells

Fetal bovine serum (FBS) or other mammal-derived factors are extensively supplemented as growth factor into culture medium. Since mammal-derived factors arouses the concern about the risk of zoonosis, serumand mammal-free culture is strongly required. We focused on sericin hydrolysates, originating from silkworm, and reported that sericin is effective as growth factor to various cells. But it is not elucidated how sericin induces the proliferation and inhibits apoptosis of the cells. In this study, inhibitor assay was done in order to identify signaling factors involved in sericin effect. In hybridoma cells, the involvement of Src was suggested, while ERK1/ 2, PP2A and p38 were not involved. In HepG2 cells, the involvement of Src and ERK1/2 was suggested. From these results, it was implied that the mitogenic effect of sericin might be transduced through different pathways depending on cell line.