The anti-tumor activity of exopolysaccharides from Pseudomonas strains against HT-29 colorectal cancer cell line

Abstract

The anti-tumor activity of extracted exopolysaccharides (EPSs) (without any side effects) of Pseudomonas aeruginosa on HT-29 colorectal cancer cell line has not been previously investigated. The extraction and partial characterization of EPS from the strains of P. aeruginosa including A (CIP A22(PTCC1310)). and B (a clinical strain) were performed. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MiT) and sulphorhodamine B (SRB) assays as well as microscopy were used to estimate the cell viability and morphological changes in HT-29 cells subjected to EPS at 0, 7.6,15.8, 31.2, 62.5 and 125 mu g/ml. The apoptotic effects of EPS were also examined by flow cytometry. The EPSs were found to be cytotoxic against HT-29 cells with 1050 values at 44.8 (EPS-A) and 12.7 (EPS-B) The counteraction of 125 mu g/ml of EPS-A (87.5 and 56.7) and EPS-B (86.7 and 592) resulted in the highest repressive rates using the MIT and SRB assays, respectively. Flow cytometric results showed that EPS-A and EPS-B could induce apoptosis (33 and 39) and necrosis (65 and 59). The extracted EPSs of both bacterial strains can be used as natural, effective, efficient and anti-cancer drugs. However, more characterization at molecular and structural levels in this respect may be required. (C) 2020 Elsevier B.V. All tights reserved.