20-hydroxyeicosatetraenoic acid is formed in response to epidermal
growth factor and is a mitogen in the rat proximal tubule.
Lin, Fangming, Amelia Rios, John R. Falck, Yuri Belosldtsev, and
Michal Laniado Schwartzman.
Department of Pharmacology, New York Medical College, Valhalla, NY
10595 and Departments of Molecular Genetics and Pharmacology,
University of Texas Southwestern Medical Center, Dallas, TX 75235
APStracts 2:0124F, 1995.
20-hydroxyeicosatetraenoic acid (20-HETE) is a major cytochrome P450
-arachidonic acid metabolite in the rat kidney and its synthesis along
the nephron is specifically localized to the proximal tubule where
receptor density for EGF is the highest. EGF stimulated endogenous
20-HETE formation in a concentration and time-dependent manner, i.e.,
from 1.6 pmol 20-HETE/mg/min to 2.6+/-0.3 and 3.0+/-0.6 pmol/mg/min
at 10-8 and 10-7 M EGF, respectively. The effect of 20-HETE on
proximal tubular cell proliferation was examined using primary
cultures of rat proximal tubular cells and proximal tubular derived
-cell lines, LLC-PK1 and OK. In both cell lines, 20-HETE increased
thymidine incorporation into DNA with maximal effect at 10-9 M.
Addition of 20-HETE to serum-deprived LLC-PK1 or OK cells for 48 h
caused a concentration-dependent increase in cell number with maximal
effect at 10-9 M. This effect was specific as structurally similar
eicosanoids such as 20-COOH-arachidonic acid, 19(R)-HETE and 19(S)
-HETE did not increase cell number. In 4-day primary cultures of
proximal tubular cells, EGF (10-9 M) and 20-HETE (10-9 M) increased
bromodeoxyuridine (BrdU) incorporation by 40 % and 28%, respectively.
Addition of both resulted in a 2-fold increase in BrdU incorporation.
Although 20-HETE synthesis in cultured cells is greatly diminished
with time, significant pM concentrations can be obtained in 4-day
cultures. Addition of 17-ODYA, an inhibitor of 20-HETE synthesis,
significantly inhibited EGF-stimulated BrdU incorporation. The
demonstrations that EGF stimulate proximal tubular 20-HETE production
and that the latter is a potent mitogen to these cells suggests that
20-HETE may act as a mediator of the EGF effect on cellular growth in
the proximal tubule.
Received 15 December 1994; accepted in final form 5 July 1995.
APS Manuscript Number F444-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.