Increased Expression of Caspase Genes in Colorectal Cancer Cell Line by Nisin

Nisin is a potent bacteriocin produced by Lactococcus lactis subsp. lactis and anti bacterial peptide. Colorectal cancer (CRC) is considered as one of the most prevalent and mortal cancers throughout the world. Genetic variations and environmental factors are responsible for initiation and development of cancer. Regulation of the apoptosis process plays an important role in the development of crc. bax, bcl2, caspase 3, 6, 8 and 9 genes are involved in induction of apoptosis.

The present study describes cytotoxic effects of nisin and bax, bcl2, caspase 3, 6, 8 and 9 gene expression levels in SW480 cells incubated with nisin at different doses and different incubation times.

The SW480 cells were treated with concentrations of nisin at different doses and different incubation times. The cytotoxic effects of nisin were studied using MTT assay. Expression levels of bax, bcl2, caspase 3, 6, 8 and 9 genes were determined by real-time PCR technique.

Our results showed that treatment with 800,1000,1200 and 1500 μg/mL nisin after 24 hour incubation at 37°C significantly reduced cell viability (P < 0.05). In the in vitro experiment, the mRNA expression level of bax, bax/bcl2 ratios, caspase 3 and caspase 9 were significantly increased (P < 0.05). In contrast, the mRNA expression level of caspases 6, 8 didn’t show any significant increase after 24 h and 48 h incubation (P > 0.05).

Our results confirm that nisin induces mitochondrial dependent apoptosis by up regulation of caspase genes expressions. The results of this study contribute to the use of nisin as a suggested therapeutic factor to reduce the progression of colon cancer