Gentamicin-induced apoptosis in renal cell lines and embryonic rat fibroblasts.
El Mouedden M, Laurent G, Mingeot-Leclercq MP, Tulkens PM
Unite de Pharmacologie Cellulaire et Moleculaire, Universite Catholique de Louvain, B-1200 Brussels, Belgium.
Gentamicin, an aminoglycoside antibiotic, induces apoptosis in the proximal
tubule epithelium of rats treated at low, therapeutically relevant doses
(El Mouedden et al., Antimicrob. Agents Chemother. 44, 665-675, 2000).
Renal cell lines (LLC-PK(1) and MDCK-cells) have been used to further characterize
and quantitate this process (electron microscopy; terminal deoxynucleotidyl
transferase-mediated dUTP-biotin nick-end labeling of fragmented DNA [TUNEL];
and DNA size analysis [oligonucleosomal laddering]). Cells were exposed
for up to 4 days to gentamicin concentrations of up to 3 mM. Apoptosis
developed, almost linearly, with time and drug concentration, and was (i)
preventable within the time-frame of the experiments by overexpression
of the anti-apoptotic protein Bcl-2, and by co-incubation with cycloheximide
(MDKC but not LLC-PK(1) cells); (ii) associated with an increased activity
of caspases (MDCK cells; bcl-2 transfectants showed no increase of caspase
activities and Z-VAD.fmk afforded full protection). Gentamicin-induced
apoptosis also developed to a similar extent in embryonic fibroblasts cultured
under the same conditions. In the 3 cell types, apoptosis (measured after
4 days) was directly correlated with cell gentamicin content (apoptotic
index [approximately 10 to 18% of TUNEL (+) cells for a content of 20 microg
of gentamicin/mg protein; kidney cortex of rats showing apoptosis in proximal
tubule epithelium typically contains approximately 10 microg of gentamicin/mg
protein). Thus, gentamicin has an intrinsic capability of inducing apoptosis
in eucaryotic cells. Development of apoptosis in proximal tubules of kidney
cortex in vivo after gentamicin systemic administration is therefore probably
related to its capacity to concentrate in this epithelium after systemic
administration.
PMID: 10869472, UI: 20330623