Effects of L-paracasei subp. paracasei X12 on cell cycle of colon cancer HT-29 cells and regulation of mTOR signalling pathway

L. paracasei subp. paracasei X12(1) is obtained from traditional cheese in northwestern China and exhibited effective anticancer activities in previous screening experiments. Here, its effects on colon cancer cell line HT-29 cell cycle and the roles of mammalian target of rapamycin (mTOR) signalling were investigated. Firstly, the effects of Lactobacillus X12 at different multiplicity of infection (MOI) on HT-29 cell cycle were detected by flow cytometry. In order to determine the specific regulators involved, cyclin D-1, cyclin E-1, the positive regulators, and p21, p16, and p27, the negative regulatory factors, were further explored by RT-PCR technique. Finally, mTOR signalling was focused to demonstrate its relationship with cell cycle arrest. Overall, the present findings suggested that Lactobacillus X12 can block HT-29 cell cycle at G(1) phase through inhibiting cyclin E-1, meanwhile enhancing p27, which were mediated by mTOR/4EBP(1)(2) signalling pathway. These results will provide a theoretical basis for further development of Lactobacillus. (C) 2015 Elsevier Ltd. All rights reserved.