Cylindrospermopsin induces oxidative stress and genotoxic effects in the fish CLC cell line

Abstract

Cylindrospermopsin (CYN) is a cyanotoxin detected in water reservoirs worldwide. The toxin is a potent protein synthesis inhibitor capable of adversely influencing a wide range of cell functions. While data on the prooxidative potency of CYN are inconsistent, genotoxic effects towards certain mammalian cell types have been described. However, such a potential on fish cells has not yet been investigated. Hence, the aim of the study was to elucidate the prooxidative and genotoxic impact of CYN on a common carp (Cyprinus carpio L.) leucocyte cell line (CLC). The cells were incubated with the cyanotoxin at concentrations of 0.1, 0.5 or 1 µg ml⁻¹. After 24 h, cytotoxic activity of CYN at the highest used concentration was confirmed by decreased cell membrane integrity and inhibited cell proliferation. Additionally, CYN at 0.5 and 1 µg ml⁻¹ increased intracellular ATP levels and decreased the reduced to oxidized glutathione ratio. Furthermore, a significant increase in the reactive oxygen species (ROS) production with concomitant changes in superoxide dismutase activity was observed after a 3.5-h exposure of the cells to the toxin. Genotoxic activity of CYN, manifested as oxidative DNA damage and elevated number of micronuclei, was also detected in exposed cells. The obtained results indicate that CYN is able to exert a wide range of adverse effects, including oxidative stress and genotoxicity in fish leucocytes.

Dietaryl‐carnitine prevents histopathological changes in tilapia (Oreochromis Niloticus) exposed to cylindrospermopsin

“…Furthermore, the mitochondrial membrane potential (MMP) was increased in CYN‐treated HepG2 cells (Štraser et al, ), and it is known that a high MMP is positively correlated with the production of ROS (Suski et al, ). According to Sieroslawska and Rymuszka (), the relationship between ROS level and mitochondrial status in CYN‐treated cells has not been studied yet. Thus, taking into account the previous works demonstrating the amelioration by LC of mitochondrial damage by different xenobiotics and/or injuries, we assume that LC was able to prevent the lesions in the mitochondrial proteins target of CYN in our study.…”

In Vitro Toxicological Assessment of Cylindrospermopsin: A Review

“…Other authors suggest that oxidative stress may be better defined as a disruption of redox signaling and control [ 58 ]. Table 4 [ 9 , 22 , 24 , 26 , 34 , 35 , 36 , 37 , 38 , 39 , 41 , 59 , 60 , 61 , 62 , 63 ] shows the in vitro studies available in the scientific literature dealing with oxidative stress induced by CYN.…”

“…These differences could be due to the different experimental models (primary cells or cell lines of various origins), CYN concentrations, or exposure periods that were employed. Moreover, given that CYN is also an environmental contaminant, it is noteworthy that few reports are available with fish in vitro models [ 34 , 35 , 61 , 63 ].…”

“…It is important to note that, to the best of our knowledge, the enzyme-modified comet assay, using endonuclease III (Endo III) and formamidopyrimidine DNA glycosylase (Fpg) to detect oxidation of pyrimidines or purine DNA bases, respectively [ 85 ], has rarely been employed to evaluate the role of this mechanism in the genotoxic potential of CYN. Only one study has investigated the oxidation of purine bases (Fpg assay) by CYN [ 61 ]. In addition, the mouse lymphoma gene mutation assay (MLA) (OECD 476) [ 86 ], which is preferred because it detects the broadest set of genotoxic mechanisms—such as chromosomal, gene, base pair substitutions, and frame-shift mutations [ 87 , 88 ]—that are associated with carcinogenesis activity, has not been performed either, despite the indications of CYN carcinogenicity for humans) [ 7 , 69 ].…”

“…In relation to fish, despite the common exposure of fish in natural environments and fish farms to cyanotoxins, there are only four studies on the genotoxic effects of CYN, yielding contradictory results, as mentioned earlier [ 35 , 61 , 63 , 77 ]. Cell-type and interspecific CYN toxicity differences may occur, because, in comparison to the concentration-dependent DNA damage reported in mammal cells [ 28 , 72 ], DNA breaks were not found in fish hepatocytes that were exposed to the same concentrations of CYN [ 35 ].…”