Experimental data supports antineoplastic effects of silkworm protein sericin against colorectal cancer cells.

Colorectal cancer (CRC) is the 3rd most common cancer in the world. Currently available therapeutic options against CRC hold limited efficacy, substantial side-effects and high costs. Exploring naturally occurring resources to find better options is required to overcome these challenges. Sericin, a naturally occurring protein secreted from silk gland of silkworm "Bombyx mori" is an alternative option in this context. In this study, sericin was extracted from locally available cocoons, while commercially available sericin was purchased for comparison purposes. Multiple bioassays were performed to evaluate the effects of sericin on cancer-related cell processes including proliferation (MTT), colony formation, migration (scratch and invasion), apoptosis (annexin-V and DAPI), cell cycle (FACS) and autophagy (AO/EB) analysis in three human CRC cell lines (SW480, SW620, HCT116). Exposure with extracted and purified sericin fractions induced anti-proliferative effects (up to 40%) in the CRC cells in a time and concentration dependent format. Exposure with low concentration of sericin inhibited migration (13-33%) and colony formation (20-46%) in the CRC cells. Sericin treatment also induced apoptotic effects in the CRC cells as reflected by annexin-V, DAPI and AO/EB staining. Sericin exposure-imposed arrest in S-phase of the cell cycle as measured by propidium iodide-based staining and flow cytometry analysis. Sericin affects vital functional properties of the CRC cells including proliferation, cell cycle, apoptosis, migration and colony formation. Further investigations are needed for the translation of sericin into a therapeutic compound.