Anticancer effects of a silkworm protein (sericin) in lung cancer cells

Background: Lung cancer is a wide-spread malignancy across the world. With the limited availability of therapeutic options, 5-year survival is low in advanced stages of lung cancer. Sericin, a biowaste protein from silkworm cocoon has shown anti-cancer potential against various cancers in pre-clinical research with minimal side-effects. Current study was designed to determine cytotoxic effects and expression modulations imposed by sericin in lung cancer cells. Materials & Methods: Sericin from local cocoons was extracted via degumming process. Human lung cancer cells (H1299) were cultured and exposed to different concentrations of extracted and commercially available sericin (0.03-1 mg/ml) for 24-72 hours. Effects on proliferation were determined by MTT dye reduction assay. Following the total RNA extraction and cDNA synthesis, expressional alterations in cell cycle (CDKN1A, CDKN1B) and stress (GADD45A, GADD45B) relevant genes were determined via real-time PCR methodology. Results: Sericin exposure induced the concentration and time dependent inhibitory effects on cancer cell proliferation. Comparable results from commercially available sericin and local extracted sericin confirmed the reliable extraction process adopted in this study. CDKN family of genes (cell cycle inhibitors) was up-regulated in response to the sericin exposure. GADD genes (markers of cell stress) were also induced in the cancer cells in response to sericin exposure. Conclusion: Lung cancer cells were responsive towards sericin exposure as observed by inhibition of the proliferation. Sericin interfered with expression levels of cell cycle inhibitor and stress related gene families. Further studies are needed to understand the anticancer potential of sericin against lung cancer cells.