Human proximal tubular cell line

Romiti N, Tramonti G, Donati A, Chieli E. Effects of grapefruit juice on the multidrug transporter P-glycoprotein in the human proximal tubular cell line HK-2. Life Sci 2004 76(3) 293-302. 

Flahn FI, FluckCW, Rainer M, Najam-ul-Flaq M, Bakry R, AbbergerT, Jennings P, Pfaller W, and Bonn GK. Analysis of glutathione in supernatants and lysates of a human proximal tubular cell line from perfusion culture upon intoxication with cadmium chloride by HPLC and LC-ESI-MS. Anal Bioanal Chem 388 1763-1769,2007. 

CSA has also been shown to cause toxico-tolerance in vitro. CsA, which is transported via the P-glycopro-tein, increases the expression of P-glycoprotein in rat proximal tubular cells [183] and in the human proximal tubular cell line HK-2 [183a]. CSA also induces the expression of HSP 70 in LLC-PKj cells, which increases tolerance to subsequent exposure to CSA [184]. 

Nanomolar concentrations of OTA resulted in the stable and irreversible dedifferentiation of MDCK-C7 cells, characterized by a distinct morphology as compared to the parent cell line (spindle-shape, pleiomor-phic, narrow intercellular spaces, increased cell size), a reduced proliferation rate and numerical chromosomal aberrations [202]. Further studies could demonstrate that OTA exposure resulted in apoptosis, which was associated with induced c-jun amino-terminal-kinase (JNK) activation [203]. Long term exposure (14 days) of human proximal tubular cells to nanomolar concentrations of OTA under serum free conditions led to cell hypertrophy, NF-kappaB activation, fibronectin secre-... 

Induction of oollagen secretion (a marker of fibrosis) has been shown in the OK proximal tubular cell line and in cultured primary human renal proximal tubular oells exposed to ochratoxin A. Collagen seoretion was both time and dose dependent, as was the induction of cell toxicity (Sauvant et al., 2005a). 

In a cultured human renal proximal tubular cell line, HK-2, a concentration-related increase in the level of ROS compared with controls was observed after 6 h exposure to ochratoxin A at 50-600 pmol/l. Pretreatment with A/-acetyl-L-cysteine, an antioxidant ROS scavenger, decreased the level of ROS and increased cell survival. A/-Acetyl-L-cysteine also reduced DNA damage at 50-200 pmol/l, as measured by the comet assay, but not at higher ochratoxin A concentrations of >400 pmol/l, at which the generation of ROS outpaced the reduction by A/-acetyl-L-cysteine (Arbillaga et al., 2007a). 

Prediction of Renal PT Toxicity with HPTC HPTC were used for the development of the first predictive renal in vitro model (Li et al., 2013) (Table 23.1). Three batches of HPTC derived from different donors were screened with 41 compounds. Human (HK-2) and porcine (LLC-PKl) immortalized renal proximal tubular cell lines were nsed for comparison. All of the 41 compounds were either widely used drugs or environmental toxicants and indnstrial chemicals with well-characterized effects on human kidneys. Thus, the in vitro results could be directly compared to human clinical data. The compounds were classified into three groups (1) nephrotoxicants that are directly toxic for PTC in human kidneys, (2) nephrotoxicants that damage the kidney in different ways and are not directly toxic for PTC in humans, and (3) compounds that are not nephrotoxic in humans. 

In a study of six mercury compounds, mercury chloride, mercury nitrate, sodium ethylmercurithi-osalicylate, methyl mercury chloride, mercury acetate and phenylmercury acetate in MDCK cells, LLC-PKl cells and human primary proximal tubular cells (hPTC) and non-renal cell lines (SAOS and Hep G2) it was found that all mercury compounds were toxic to all cell types as evidenced by neutral red uptake, thymidine incorporation and the MTT assay [189]. However, sodium ethylmercurithiosalicylate, methyl mercury chloride and phenylmercury acetate were one order of magnitude more toxic than the other compounds. In addition the GSH synthesis inhibitor L-buthionine sulfoximine (BSO) potentiated the toxicity of all mercury compounds [189]. In a study using primary rabbit proximal tubular cells it was also shown that methyl mercury chloride is more toxic than mercury chloride [190]. Differences in the extent and rate of metal uptake were also evident. Maximum cellular uptake of Hg " occurred within 6-24 hr after exposure and was not concentration-dependent, whereas maximum uptake of CHgHg" occurred within 3 hr of exposure and was concentration- dependent [190]. 

There have been several investigations into the use of hormonally defined medium in order to maintain the differentiation of primary cells, as it is suspected that serum may be a factor in dedifferentiation. The application of defined medium also allows a more standardized approach to cell culture delivering greater reproducibility and transferability. For renal tubular epithelial cells defined medium supplements have been described as far back as 1982 [148], We have been, over the last number of years, successfully cultivating human renal proximal tubular cells (primaries and cell lines) in serum free hormonally defined medium containing EGF, hydrocortisone, insulin, transferrin, and sodium selenite using DMEM-Hams F12 as the base medium [36, 112, 114, 149], Both the HK-2 cell line and the RPTEC/TERT1 have been developed in serum-free conditions. 

Further evidence to support a direct toxic effect of AmB on renal cells is the demonstration of increased apoptosis in proximal tubular and medullary interstitial cell lines [65]. The occurrence of apoptosis has also been confirmed in an in-vivo model in rats in which AmB administration also caused hypokalemia, loss of concentrating ability and dehydration. Interestingly, prevention of apoptosis by recombinant human insulin growth factor-1 (rhIGF-1) ameliorated the tubular toxidly indicating the importance of apoptosis in AmB-induced renal tubular toxicity process. A possible mechanism for this action is suggested by a recent study that has demonstrated that AmB exposure increases cellular ceramide as well as sphingomyelin levels in proximal tubular cells [66]. It is noteworthy that... 

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