Abstract
We searched the genomic database (NCBI) and found a gene which encodes a Class IIb bacteriocin plus with GXXXG motif in Lactobacillus (L.) paracasei ATCC 27092, named BD21. We amplified this DNA fragment by PCR and ligated with an overexpression vector pAB to give pAB-BD21. The MTT assay result showed that BD21 can inhibit the growth of human colon adenocarcinoma cell, SW480. Moreover, flow cytometry analysis also showed that BD21 cause apoptosis and partly necrosis in SW480. Although we found that BD21 can induce apoptosis and partly necrosis in SW480, the mechanisms are not clear. In this study, we show that the levels of caspase-8, caspase-7, caspase-9, caspase-3 and SW480 necrosis marker cyclophilin A had significantly increased. Moreover, Bid may contributed to released the AIF, cytochrome C and Smac from the mitochondria to the cytosol according to the results of Western blot and the SW480 necrosis marker cyclophilin A are also increased. In summary, BD21 may indirectly or directly activate the death receptor and cause apoptosis and necrosis in SW480 cell.