Inhibition Effect of Cell-Free Supernatants of Environmental Acanthamoeba Strains on the Viability of Metastatic Cell-Lines

Abstract

It is known that some of the therapeutic agents against cancer cells are isolated from natural sources such as plants and animals. However, due to increasing drug resistance, studies on the discovery of new sources are needed. In this study, it was aimed to investigate the inhibition effects of four native Acanthamoeba strains on different cancer cell lines (MDA-MB-231, PC3, MAT-LyLu). 3T3 cells were used as normal cell line. All strains were recultured by using non-nutrient agar spread by heat-inactivated Escherichia coli ATCC 25922. A.castellanii ATCC 50373 was used as the standard strain. Molecular identification of the native Acanthamoeba isolates was done by polymerase chain reaction (PCR) and DNA sequence analysis using specific primer pairs (P-FLA-F, P-FLA-R, JDP-F, JDP-R). Axenic cultures of all strains were obtained in 25 cm2 tissue culture flasks and in peptone yeast extract glucose (PYG) medium. In order to investigate the effect of cell-free supernatants obtained from axenic cultures on cancer cell lines and 3T3 cell viability, MTT method was applied using different concentrations of cell-free supernatants (1%, 2%, 5%, 10%, 15%). It was determined that the viability of 3T3 cells was not affected by any Acanthamoeba cell-free supernatants (p≤ 0.05). All of the samples tested were found to have a significant inhibitory effect (p<0.05) on the viability of PC3 and MAT-LyLu cells (human and rat prostate cancer cell line). However, none of the samples had an inhibitory effect on the viability of MDA-MB-231 (breast cancer cell-line). Two native Acanthamoeba cell-free supernatants showed higher inhibitory potency (28% and 21.9%) at 2% concentration against PC3 cells compared to the reference strain (16%). Similarly, the same Acanthamoeba samples were also shown to have a better inhibition potential on the viability of MAT-LyLu cells than the reference strain. It was found that the inhibitory potential of Acanthamoeba cell-free supernatants may not be related to proteins and proteases. The results obtained from this study showed that Acanthamoeba species living in the aquatic environment isolated from our country have a potential inhibitory effect against the tested cancer cell lines. In addition to plants and animals, Acanthamoeba cell-free supernatants can also be a source for natural therapeutic substances that act against cancer cells. However, it is necessary to carry out new studies using more strains in order to detect strains with higher inhibitory effects.