Human Proximal Tubule Epithelial Cells (HK-2) as a Sensitive In Vitro System for Ochratoxin A Induced Oxidative Stress.

Enrique García-Pérez,Hwa-Young Kim,Hyun Jung Lee,Dojin Ryu,Hae Dun Kim

doi:10.3390/toxins13110787

Enrique García-Pérez, Hwa-Young Kim + Show 3 more

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https://doi.org/10.3390/toxins13110787

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Abstract

Ochratoxin A (OTA) is a mycotoxin that is potentially carcinogenic to humans. Although its mechanism remains unclear, oxidative stress has been recognized as a plausible cause for the potent renal carcinogenicity observed in experimental animals. The effect of OTA on oxidative stress parameters in two cell lines of LLC-PK1 and HK-2 derived from the kidneys of pig and human, respectively, were investigated and compared. We found that the cytotoxicity of OTA on LLC-PK1 and HK-2 cells was dose- and time-dependent in both cell lines. Furthermore, increased intracellular reactive oxygen species (ROS) induced by OTA in both cell lines were observed in a time-dependent manner. Glutathione (GSH) was depleted by OTA at >48 h in HK-2 but not in LLC-PK1 cells. While the mRNA levels of glucose-6-phosphate dehydrogenase (G6PD) and glutathione peroxidase 1 (GPX1) in LLC-PK1 were down-regulated by 0.67- and 0.66-fold, respectively, those of catalase (CAT), glutathione reductase (GSR), and superoxide dismutase 1 (SOD) in HK-2 were up-regulated by 2.20-, 2.24-, and 2.75-fold, respectively, after 72 h exposure to OTA. Based on these results, we conclude that HK-2 cells are more sensitive to OTA-mediated toxicity than LLC-PK1, and OTA can cause a significant oxidative stress in HK-2 as indicated by changes in the parameter evaluated.

Highlights

Ochratoxin A (OTA) is a potent mycotoxin that is a possible human carcinogen classified in Group 2B by the International Agency for Research on Cancer (IARC) [1]
After 72 h OTA exposure, HK-2 cells up-regulated the transcription of CAT, GSR, and superoxide dismutase 1 (SOD), which are important antioxidant enzymes required for the detoxification of reactive oxygen species (ROS) and regeneration of GSH
glucose-6-phosphate dehydrogenase (G6PD) and glutathione peroxidase (GPX) mRNA levels in LLC-PK1 cells were the only genes affected after 72 h OTA treatment by down-regulating its transcription, which may indicate that longer OTA exposure time is required to observe an adverse effect in LLC-PK1 cells

Summary

Introduction

Ochratoxin A (OTA) is a potent mycotoxin that is a possible human carcinogen classified in Group 2B by the International Agency for Research on Cancer (IARC) [1]. Due to the different growth requirements of the fungal species that produce OTA in the genera of Aspergillus and Penicillium, OTA can be found in a wide variety of agricultural commodities and their processed products, including cereal grains, coffee, nuts, and wine [2,3,4]. While epidemiological data are lacking, the array of toxicities in animals associated with dietary exposure to OTA suggests OTA as a public health concern. OTA is well known for its kidney toxicity in different animal species, and it causes kidney tumors in rodents [5,6]. OTA is known to be hepatotoxic, teratogenic, mutagenic, and immunosuppressive [7,8,9]. The exact mechanism of OTA toxicity or chemical carcinogenesis has not been elucidated yet. According to the proposed mechanisms related to OTA toxicity, acute and chronic toxicity of OTA are related directly or indirectly to (a) inhibition of mitochondrial respiration and ATP production [10,11]; (b) inhibition of protein synthesis [12,13]; (c) OTAinduced DNA damage [14,15]; (d) lipid peroxidation [16,17,18]; and (e) the production of Toxins 2021, 13, 787 chronic toxicity of OTA are related directly or indirectly to (a) inhibition of mitochondrial respiration and ATP production [10,11]; (b) inhibition of protein synthesis [12,13]2; o(fc1)

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