Arginine deiminase originating fromLactococcus lactisssp.lactisAmerican Type Culture Collection (ATCC) 7962 induces G1-phase cell-cycle arrest and apoptosis in SNU-1 stomach adenocarcinoma cells

Abstract

There are multiple lines of evidence that lactic acid bacteria (LAB) exert cancer-preventive effects. However, the underlying mechanisms are poorly understood. In the present study we found that the cytoplasmic fraction ofLactococcus lactisssp.lactisAmerican Type Culture Collection (ATCC) 7962 exerted the strongest antiproliferative effects (half-maximal inhibitory concentration (IC50) = 17 μg/ml) in SNU-1 human stomach cancer cells and arginine deiminase (ADI;EC3.5.3.6) activity. We also cloned, expressed and purified ADI fromL. lactisssp.lactisATCC 7962 (LADI). Both purified ADI fromL. lactis(PADI; IC50 = 2 μg/ml) and recombinant ADI originating from LADI (IC50 = 0·6 μg/ml) inhibited the proliferation of SNU-1 cells. LADI induced G0/G1-phase arrest, sub-G1accumulation, DNA condensation and DNA fragmentation in SNU-1 cells. 4′,6-Diamidino-2-phenylindole (DAPI) staining and DNA fragmentation data provide evidence that LADI induces apoptosis in SNU-1 cells. LADI increased the expressions of p53 and p27Kip1, and decreased the expressions of cyclin D1, c-myc and Bcl-xL in SNU-1 cells. However, LADI had no effects on the expressions of p21Cip1and Bcl-2. Collectively, these data indicate that ADI induces apoptosis and G0/G1-phase arrest of SNU-1 cells, which might contribute to the chemopreventive potential of LAB.