In vitro cytotoxic activity of Lactobacillus plantarum BS25 and Pediococcus acidilactici S3 cell free supernatants against colorectal cancer cells (HCT 116)

Abstract

Colorectal cancer is one of the leading causes of mortality worldwide and there is a need to develop chemotherapeutic agents that induce a specific cell death that is less inflammatory. This research focused on the evaluation of the cytotoxic and apoptotic potentials of cell free supernatants (CFS) from two lactic acid bacteria strains (Lactobacillus plantarum BS25 and Pediococcus acidilactici S3) isolated from Philippine traditional fermented foods against the human colorectal cancer cell line (HCT-116) via 3- (4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Results showed that BS25 and S3 CFS exhibited cytotoxicity on HCT-116 cells, with average IC50 values of 27.535% v/v and 26.090% v/v, respectively. Moreover, the cytotoxicity that was observed was further validated via morphological analysis. HCT-116 cells characteristically showed membrane blebbing, granulation, and rounding up, which are typical morphological symptoms of cell death, when treated with the bacterial CFS from both strains. TUNEL staining confirmed DNA fragmentation in HCT-116 cells upon treatment with 100% v/v CFS from BS25 and S3 within 12 hours, which is an indicator of apoptosis. These results show that the CFS from L. plantarum BS25 and P. acidilactici S3 appear to be potentially promising anti-cancer agents for adjunct therapy, which can be further purified via bioassay-guided fractionation methods.