Abstract: Osteopontin. (OPN), a secreted acidic phosphoglycoprotem found in many tissues and body fluids, is produced in increased amounts in response.
Osteopontin inhibits nitric oxide production by activated RAW264 7 macrophages
and cytotoxicity
.
Ellen
E. Rollo,
Departments Jersey
Abstract:
ofBiological
Osteopontin
macrophage
(OPN),
and
thesis. A human bacteriophage encoded protein
OPN T7-based purified coli carrying
inhibited
NO
11AW264.7 cells plus interferon-’y.
with
abundance shape
an
of of
the
a
and
tPj.coiogy
secreted
nitric
acidic
oxide
(NO)
syn-
by
the the of
cells
Rutgers
Words:
macrophage-like
resistance to Rickettsia pears to map closely
to the
some
5, consistent
of macrophages chemotactic
OPN-dependent
decrease
NO
synthase
in
mRNA.
curve,
with
the The
a maximal
macrophage-mediated
60: 397-404;
with
1996.
cytokines
.
inflammatory
response
mice
tumor
cells
the course and is a polyclonal immunoglobulin B cells this
The protein a thrombin
contains cleavage
several site
binding sequence Gly-Arg-Gly-Asp-Ser facilitates cell attachment and signaling grin. OPN is present in human plasma the
nM
primary
(J. Harris,
personal
function
of OPN
phosphoglycoprotein fluids [see refs.
and
correlation
that
ETA1/OPN
of injection smooth muscle
macrophages
[12],
metastatic
been
OPN
[9]. OPN is also cells [10]. The in MRLIMpJexpress abnorcorrelates with
the
contribute
malignant
to
phenotype
cells secrete at compared with ref.
between
of tumor
also
13 for review]
production cells
least their
[14,
and
of OPN 15].
a
and
Consistent
is the finding that the concentration of patients with disseminated carci-
is considerably in facilitating
[see
noted
capacity
individuals
may
it
transformed protein when
counterparts has
may
mechanism [5, 8]. Subresults in the infiltration
elevated
[16].
Strong
when evidence
development
compared for
with
a direct
of a malignancy
norrole
of
comes
conserved moand the integrin
(GRGDS), which via the av3 inteat about 30 ng/mL,
communication). is not
mal
1-4
site
murine autoimmune disorder. OPN also appears to augment
nomas Osteopontin (OPN) is a ubiquitous found in a variety of tissues and body
thought
severity of the disease [1 1]. Because OPN B cell activator, capable of stimulating (Ig)M and IgG production by mixtures of
with this observation of OPN in the plasma
INTRODUCTION
locus
defense of ETA1
to the vascular
of cancer cells. Many 10-fold more of this
destruction.
Ric
the
a rapid response administration for
infection, and it apon mouse chromo-
tsutsugamushi
subset of proliferating T cells (CD4, CD8) lpr inbred mice with autoimmune disease mally high levels of OPN in a manner that
the
or -1
New
the OPN cDNA has been cloned as gene-i (Etal) on the basis of its activation of T cells [5]. Moreover, alleles of Etal is associated with
macrophages toward NOcells, an action that was synthase inhibitor, NG Inhibition of NO production
inducible
Biol.
for reviews]. tifs, u 1uding
Piscataway,
In this latter context, early T cell activation rapid induction after expression of certain
nontransformed Key
University,
natural killer (NK) cells express OPN in response to activation by various cytokines or inflammatory mediators, suggesting that it may also be involved in host defense reactions [1, 2, 5-7].
constitute cutaneous
dose-response
from
J. Leukoc.
Toxicology,
with lipopolysaccharide also inhibited the cytolytic
effect over a narrow range of OPN concentrations, suggested a complex interaction of OPN with cell surface receptors. Our data support the hypothesis that tumor-cell-derived OPN functions to protect the tumor
T. Denhardt and
cDNA was cloned into vector, pET8C, and from an induced culture the plasmid. Recombinant
production
stimulated OPN
activity of the activated sensitive P815 mastocytoma blocked by the NO monomethyl-L-arginine. correlated
Sciences
and David
found in many tissues and body in increased amounts in response and after malignant transformawe examined the action of OPN on
cytotoxicity
Escherichia
L. Laskin,t
08855
phosphoglycoprotem fluids, is produced to certain infections lion. In this study
OPN
Debra
known,
Although considerable
data suggest that it plays a role in various mineralization processes, both normal and pathological. Fibroblasts, epithelial cells, osteoclasts, macrophages, T lymphocytes, and
Abbreviations: FBS, fetal bovine serum; IFN, interferon; iNOS, inducible nitric oxide synthase; IPTG, isopropyl -D-thingalactopyranoside; LPS, lipopolysaccharide; i-NMMA, NCmonomethyl.L-arginine; OPN, osteopontin; NK, natural killer; Ig, immunoglobulin; SDS, sodium dodecyl sulfate; PAGE, polyacrylamide gel electrophoresis; DMEM, Dulbecco’s modified Eagle’s medium. Correspondence: Dr. David Denhardt, Nelson Biological Laboratories, P0 Box 1059, Rutgers University, Piscataway, NJ 08855. Present address of Ellen E. Rollo: VAMC-Northport, Building 62 (151), 79 Middleville Rd., Northport, NY 11768. Received March 14, 1996; revised June 3, 1996; accepted June 7, 1996.
Journal
of Leukocyte
Biology
Volume
60,
September
1996
397
from the observation that a reduction in OPN expression in transformed cells by means of an anti-OPN antisense RNA reduced their tumorigenicity and their ability to form cobnies in soft agar [17, 18]. In addition, antisense-mediated down-regulation of OPN expression in JB6 mouse epidermal cells inhibited TPA-induced anchorage-independent growth [i9]. The question addressed in this study concerns mechanisms by which tumor cells evade host immune defenses, in particular nitric oxide (NO). NO is a highly reactive free radical
implicated
and the produced
inhibition of cellular proliferation from L-arginine by NO synthase
in
macrophage-mediated
of which
(Type
II, or iNOS)
Western
blotting
human
OPN
and
immunoprecipitation
antibody
LF7
with
confirmed
the
the
identity
bone-derived
ofthe
Western blotting Proteins fate
were
electrophoretically
(SDS)
washed,
blocked
TrisHC1,
pH
The
transferred
polyacrylamide with 7.5,
primary
gels
0.5
antibody
3%
to
gelatin
M NaC1, was
from
sodium
nitrocellulose. and
and
0.1%
Tween
incubated
anti-2arC
(for
dodecyl 20
with
detecting
mouse
systems,
[20-24]. (NOS), one
by various
induction
of
iNOS
in
for
the
targets. metastasis
It is form
(A)
kidney
cytolytic
proximal
concomitant
cytotoxicity
the
NO-sensitive
P815
MATERIALS
kQa 97.4
action
tubule
rOPN
of
facilithe
31.0
epithelial
OPN may protect cytotoxicity by into synthesize NO [26].
of the
(B)
kQa
action of OPN on macrophages and
activated
mastocytoma
AND
or LF7
that
To test this possibility, we analyzed the NO production by activated RAW264.7 the
mM
4
cytokines
Because OPN and suppresses
cells [25], it has been proposed tumor cells from macrophage-mediated hibiting the ability of macrophages
20
antibody.
cytotoxicity
is induced
tumor and
in OPN)
at least
model
were
primary
42.7
toward formation
sul-
Membranes
662
in some
protein
as OPN.
and inflammatory mediators. This enzyme effects the high output of NO by activated macrophages that is responsible, macrophages tates tumor
anti-
induced
cells
97.4
.4 66.2
toward
rOPN
662..
cells.
31.0
METHODS
21.5
Reagents Restriction
endonucleases,
and
BamHI
erly,
MA),
linkers
other
were
Pharmacia
LKB
Mannheim (Indianapolis, (4.00 units/pt was a kind Brunswick,
NJ).
028:B12, MO). by
was The
Dr.
against
and column.
(Arlington
C-terminal
Sodium
Cloning
CA),
portion
in
E.
All
cell
and expression
(no.
generously
was
media
with
Limuiws
of 60-100
provided
was
fused
to
purified
from free
662*
raised
OPN
affinity
were
97
Louis,
antiserum
CJS1)
culture
by assay
at a sensitivity
(St.
of mouse
coli [27]
[5 Crjchromate
IL).
was
IFN-y (New Serotype
Company
Anti-2arC
kQa
Boehringer-
coli,
E.
(C)
(Bev-
WI). Murine Laboratories
from
LF7
MD).
NcoI
and
BioLabs NJ),
Chemical
antibody
Bethesda,
as determined Mesa,
(LPS)
OPN
England
(Madison, Biomedical
Sigma
synthesized
Heights,
endotoxin, Costa
bone
80-amino-acid
-galactosidase an OPN
IN), or Promega gift from Pestka from
(NIH,
enzymes,
New
(Piscataway,
Lipopolysaccharide
Fisher
the
from
Biotechnology
purchased
anti-human L.
DNA-modifying
purchased
rOPN 42.7
on
Amersham
of detectable
amebocyte
lysate
Fig.
(ICN,
1. Synthesis
pET8C.OPN;
of human OPN cDNA
lane
lecular-mass The
900-base
into
the
from using which OPN MD.
17
Dr.
coding
region
promoter-based Studier,
Brookhaven
and
BamHI
linkers.
lacked mRNA
exon
5 encoding
provided
by
recombinant
of human
plasmid
F. W.
NcoI
The
pair
Drs.
OPN
expression
amino
used
acids
OPN-expressing
was
no. 42-55,
and
M. Young,
plasmid
was
coli
BL21(DE3)pLysS.pET8C.OPN,
which
1 mM IPTG for 3 h at 34#{176}C [28]. a large amount of OPN protein
398
Journal
to
of
Leukocyte
was
As illustrated was produced
Biology
grown in lane by the
Volume
NY),
ards;
purification
full-length
NIH,
Bethesda, into
and
the
The
E.
coli
3, 4):
induced
with
protein;
September
side: lane
3, inclusion
6,
1996
fractions cell
on
standards; of the
purified
Confirmation
OPN PAGE
lane lane
protein
was
gel (lanes
LF7 antiserum; lane protein as described
blot
lane
4, inhibition in Materials
purified
gel.
7,
4, inclusion
purified
a Coomassie lane
Western blotting and Methods.
2,
Right: column
OPN
protein.
blue-stained
Western
OPN
body
cut.
hydroxyapatite
of the on
stand-
sulfate
by inhibition standards;
of the
lane
ammonium
analyzed
1, 2) and
1, low-molecular-mass 3, Western
pellet;
identity
pro-
polyacrylamide
2, low-molecular-mass
5, 20-40%
low-molecular-mass (C)
lane
low-mo-
osteopontin
an SDS-12%
preparation
33.
blue-stained cultures: Lane 3, uninduced
5, SDS-PAGE
of recombinant
lysate;
lane
Coomassie
and induced pET8C; lane lane
Purification
body
supernatant;
(A)
pET8C.OPN;
(B)
1, induced
of OPN.
of uninduced 2, induced
4, induced
of selected
lane
SDS-10%
strain
4 of Figure l#{192}, induced culture.
60,
Analysis
fraction
gels lane
standards.
preparation lane
of the
create then
Left
variant,
expression
BL21(DE3)pLysS
(a gift
Upton, a splice
tein.
cloned
pET8C
transfected
isopmpyl--D-thiogalactopyranoside-(IVFG)-inducible
E.
was
Laboratory,
cDNA
L. Fisher
Ia cDNA vector
National The
and
SDS-12% polyacrylamide 1, uninduced pET8C;
pg/mL.
blotting the
protein of the
(lanes
purified using
OPN
anti-OPN
purified
OPN
(for
detecting
human
OPN)
BL21(DE3)pLysS.pET8C [29].
After
washing,
anti-rabbit
IgG
Hercules,
CA).
blot
with
drogen
the
(H+L)
we
erum
To
the
inhibition
preincubated
identity
of an
Western
blotting
as
excess
of
with
1 h,
centrifuged,
recognize
OPN)
Cultures an
of
coli
E.
described
antibody.
in
resuspended
the
in water,
7.0,
and
0.01-0.5
M at
sodium
-0.3
analyzed
dialyzed
blotting.
Fractions
buffer
electrophoresed bands
on
excised,
sodium
containing
acetate/0.1%
shaking.
OPN
remove
was
traces
gels
basis
antibody
of the
to be
lysate
of
the
described
body
su-
OPN
was
sue
buffer,
[32].
culture
OPN
Cytotoxicity
were
bach
pooled, the
in
OPN 10
overnight, 90%
and
LF7
of the
a!.
was
quantified Unless
supplemented
cytotoxicity
assays.
culture
TIB
resistant/NO-sensitive can
Type
medium
GIBCO, every
Preparation analysis
TIB
to
tions
of OPN
cells
were
35-mm a
Western
days
64)
line
were
supplemented MD),
when
P815 in
with
10%
(Amen-
fetal
penicillin,
humid
atmosphere
of 5%
-80%
confluent.
washed
bovine and
and
incubated
blot
cDNAs
probe,
used
the
fragment cells (3000
HindIH of
the
was
Plus ride, was
OH)
membrane and then
probes
of mouse
nitric
oxide
included
OPN
cDNA
synthase
Kit
from
[27],
25 tCi Arlington
cDNA
and
from
for
measured
at 540
nm
flat-bottom
tis-
cytotoxicity
man
LS5000CE
and
-
with
is
occasional
the
of 10%
Triton
in
jiL
medium
measured
wells
cells
was
P815
determined
cells. was
with
1 h, added
8 h) RAW264.7 After
incu-
removed
the
use
Instruments,
calculated
using
containing
determined
for 45
iO’
.
from
of a BeckInc.,
the
following
spontaneous release)/(Maximum % cytolysis, where spontaneous
-
100%
X
target for
(Beckman was
target
labeled
ratio
and
of culture
x
(for This
for RAW264.7
counter
was
X-100
stimulated
or
concentra-
1 h in a sterile
The 2
After with
incubated
and
of3:1.
FBS.
various
medium,
medium,
ratio
release
measured
of radioactivity
and
swirling. in
Cr release
release)
5% medium
for
scintillation
(Experimental spontaneous
IFN-y
in all
flat-bottom
mastocytoma
(E:T)
51
with
of fresh
of [5tCrjchromate
containing
.
used
for 8 h at 37#{176}C.P815
radioactivity
Specific
jiL
U/mL
in fresh
released
CA).
100
DMEM
was
in 96-well
in DMEM
with
resuspended
dish
FBS
plated
of Lors-
red-free
iCi
h at 37#{176}C,50
release
from
dish
washed,
procedure
phenol
were
100
250
petri
16
well,
target
cells
by lysing
target
cells
release
was
mm.
Spontaneous
results
show
only.
re-
Maximum with
20 piL
25-30%
of
release.
analysis
stated
obtained
NcoI
the
as the
96-well
of the
cells/well
refed
to be optimal
Statistical
a -actin
(iNOS)
random primer was labeled with 10 mCi/mL; Amersham Corp.,
isolated After
bridized
blot
(SO
nitrite
otherwise,
from one
at least
of three
the three
or more
separate similar
an
average
experiments
±
SE
of the
or triplicate
values samples
experiments.
RAW264.7
of [a32P]dCTP Heights,
IL)
RESULTS
Pharmacia.
blot analysis
Cincinnati, dehyde.
fragment
Oligolabeling
Northern RNA
Northern
inducible
[31]. Each Ci/mmol,
using
for
i0’
plus
with
of the
each
total
x
resuspended
well
Unless The
was
using
were
supernatant
sodium
heat-inactivated cells
at an effector-to-target
release SO
CO2,
samples
x
incubated which was
medium
the
with
indicated,
5%
were LPS
again,
formula: lease
and
probes for Northern
Ul-
dishes (0.75 Cells, untreated
of culture
by a modification
ng/mL
then
Fullerton,
Dulbecco’s
tg/mL
of radiolabeled
50
(TNFa)[22]
grown
LKB
IFN-’y, were stimulation, and
reader
otherwise
at 6
cells
labeled
were
to each
Type
factor-a
jiL)
reaction
of the
RAW264.7
bacterial
cells
with
(American
necrosis cell
no.
37#{176}C in a
3-4
RAW264.7
tumor
mastocytoma
(DMEM)
at
line
the
Gaithersburg,
streptomycin
subcultured
and
Collection
Eagle’s (FBS,
ig/mL
71)
mouse
Culture
modified serum
cell
no.
(75
Griess
with
dishes
100
bation
monocyte/macrophage
was intensi-
an
culture FBS.
centrifuged,
microplate
[22].
without
native
antibody
tissue without
100 U/mL 1 h before
Aliquots
absorbance
(GIBCO)
cells
Collection
OPN
Band
using
of macrophage-mediated
with
1C).
mouse
the
solution
plates.
et
tissue
anti-OPN
inhibition
solution.
autoradiograms
points,
by the
EL31O
2 h at 37#{176}Cthe
to be OPN
the
The
mM
methanol
SDS
confirmed with as
West-
were
with
a
Cell culture Culture
rehybridized prehybridization
by
M sodium
(Pharmacia).
nitrite
experimentally
The
and the
hybridization
stripped
0.015
that
fresh
blots
M NaCl,
SDS
scanning
time
Measurement
using
and
for
a Bio-Tek
gradient.
Both
was
with
Fractions
with
above
0.15
1.0%
plating.
various
assayed
standard
saturated,
gels,
by incubation
culture
in
autoradiographed. the
of NO production
h after at
7.0. OPN
and
together,
cells were plated into 24-well in phenol red-free DMEM
2
step
temperature
that
preliminary
incubation
generated
by
washed
except with
quantified
usually
does
phosphate
of the by
and
tL)
20%
(PAGE)
solution
band
specifically
replaced
Measurement
OPN
column
in water.
signal
above,
XL densitometer
removed
inclusion
pH
eluted
at room
a single of the
induced
(Fig.
7.4,
were
procedure
containing
7.0)
majority
from
showed
the
electrophoresis
resuspended
ability
blocked
the
blotting
pH
and
of
M sodium
(pH
OPN
precipitated
of SDS,
polyacrylamide on the
the
SDS,
1B,
SDS-polyacrylamide
and
and
mm
30
containing
were
hybridized
to
induced,
not
cut
buffer, the
preparative
minced,
but
from
0.01
gel
7,
for
as described
troScan
ability
of the
a hydroxylapatite
phosphate
by SDS-polyacrylamide
grown,
a series
sulfate
on
sodium
In
OPN
phosphate
M
[30].
against
pH
were
or treated with 100 ng/mL LPS and/or with various dilutions of OPN added
in Figure
saturated,
ammonium
chromatographed
membrane
RAW 264.7 106 cells/well)
shown
40%
the
ties
protein)
its
boiling
blots
probes
coli
K.
of
iNOS
removed
antis-
induced
(depleted
As
precipitate
20-40%
LF7
induced
were
bodies that
would
Thus
hy-
hybridization,
and
probe
in a Western
follows:
by a modification
[29].
inclusion
sulfate
pernatant.
eluted
et al.
0.02%
After
-actin citrate,
washed
human OPN made
we established
ammonium
ern
as primary
preparation
accumulate
experiments
pH
supernatant
in Sambrook
signal
the
BL21(DE3)pLysS.pET8C
body
on the plus
OPN
(containing
the
of recombinant
inclusion
not
and
used
Purification
an
lysate
(Bio-Rad,
visualized
in methanol
solution.
goat
peroxidase
was
coli
antibodies
affinity-purified
to horseradish
BL21(DE3)pLysS.pET8C.OPN for
with
E.
an
coli
anti-E.
incubated material
verify
with
neutralize
4-ch.loro-1-naphthol
performed was
was
conjugated
mg/mL
peroxide.
blot,
blot
to
Immunoreactive
0.5
pretreated
lysate
using 10% added
using and
Tri-Reagent
analyzed
electrophoresis, (DuPont-NEN, 50%
deionized
(Molecular
on
1.5%
agarose
the
RNA
gel
Boston, formamide,
was
MA). 1.0%
Research gels
Center
containing
blotted
dextran sulfate for 30 mm at 42#{176}C.The at a concentration of 5 x iO dpm/mL
formal-
Kinetics cells
of NO synthesis
by activated
RAW264.7
to a GeneScreen
Membranes SDS,
Inc.,
were 1 M sodium
prehy-
RAW264.7
chlo-
periods linear
denatured probe of hybridization
Rollo
et a!.
OPN
inhibits
cells
were
incubated
up to 72 h. NO production over a 6-8 h period, reaching
induction
of iNOS
and
with
IFN-y
was found maximum
macrophage
and/or
LPS
for
to be roughly levels after
cytotoxicity
399
To confirm
24
22
that
OPN
was
responsible
of NO synthesis, the OPN with the anti-2arC antibody nab region of recombinant
.
U)
20 U
4,
Figure 0
16
the ability OPN with
14
action
incubation
of OPN
of OPN to reduce preimmune serum
of OPN,
for the
preparation was prepared against mouse OPN [27].
although
with
the
antibody
NO production. also appeared
to a lesser
inhibition
preincubated the C-termiAs shown in abrogated Incubation to inhibit
extent.
of the
Neither
anti-
0
E
OPN serum nor preimmune NO production. Figure 5 illustrates the
12
C 4)
10
4-’
8
4.’
z
--
10
10.2
100
OPN
and
1O
102
IFN-’y.
cells.
Dose-dependent
Cells
IFN-yplus of
OPN.
action
at 5
x 105/well
100
ng/mL
After
15
on NO production
in a 96-well
LPS h,
of OPN
in the
dish
were
presence
supernatants
ofthe
were
The
at about
(pM)
by RAW
264.7
activated
with
U/mL
indicated
concentrations
collected
and
100
nitrite
with
stimulation, The total or absence reaching
content
determined.
inhibitory
6 h. An
duction 2.
-30
tion
kinetics
action
h of stimulation (100 [33].
with
optimal
units/mL IFN-y and As measured either
or the final
yield
of product,
concentrations
100 ng/mL by the rate
of OPN
was
as early
evident
NOS
inhibitor
L-NMMA
Effects
of OPN
Figure
2
on by
in the preswith LPS
was
first
apparent
in NO
as about
6.5
pro-
h after
with maximum inhibition of 60-65% at 8 h. yield of NO produced by the cells in the presence of OPN appeared to be approximately the same, a plateau of about 70-80 nmol per 5 X 10” cells; of OPN the cultures cultures to reach the
took plateau.
about
of in-
LPS; data not of NO produc-
the two mediators
resulted
effect
production
reduction
OPN
together
0
(pM)
0.1
1
10
yielded the most effective induction, while LPS alone was the least effective. The addition of L-arginine to the cubtures increased NO production, whereas the addition of the pendent inhibition fect of L-NMMA
any
of NO
50%
OPN
had
a 72-h period simultaneously
approximate
however, in the presence twice as long as control
ducers shown)
alone
activated RAW264.7 cells over ence or absence of OPN added
0_
Fig.
serum
s4
OS
1*-
I-&th
in a concentration-de-
of nitrite production. The could be blocked by excess
inhibitory L-arginine.
ef-
on NO production 50
shows
that
picomolar
inhibited
NO
production
with
plus
IFN-’y
LPS
by with
studies among OPN.
is
most
The
stimulated 40
of about
these OPN
conditions. synthesized
4.
a’.
3. Northern
mRNA
levels
stimulated trations
blot as
with (pM)
Northern
LPS
autoradiogram; diographic
and
of OPN
blotting
as bottom
signals
analysis
a function IFN-’y
of the of
10
(pM)
action
OPN in the
presence
for 8 h. RNA
was
described
in
Materials
panel,
normalization
to the
3-actin
signal.
of OPN
on
concentration. then
of the extracted and of the
iNOS
and
OPN
RAW264.7 indicated and
Methods. OPN
and
were concen-
analyzed Top iNOS
by panel,
autora-
production,
data
not
OPN was responsible To establish that ity,
U
‘4. 0
0
E
we
used
These
data
for the inhibition NO was responsible
L-NMMA,
an
ability
confirmed
inhibitor
of NOS, RAW264.7
The
to synthesize suppressed
NO and to kill by L-NMMA with concentration
that
of cytotoxicity. for the cytotoxic-
of activated
production.
L-NMMA
C
shown).
to block
NO
cells
p8i5
mastocytoma a similar dependence
both
cells
was on the
that
have
[33].
4., 4.,
z
DISCUSSION Among
the
been
implicated
received
4. Effect ofanti-OPN
Fig.
production.
RAW264.7
100
ng/mL
The
bars
room
LPS labeled
(0; d
mune OPN
cells
f represent
with
that
anti-2arC
e represent,
respectively,
In preliminary the
production.
effective 0.05
P
100
U/mL
or presence
was
of NO IFN-y
preincubated
for
(c)
anti-2arC
antiserum
the
dilution
2arC
or
1 h at
preparation
was the
effect
t-test).
results IFN-y,
and
NO synthesis
negligible
(3-5%).
The
cells
The ability pronounced
LPS.
OPN itself A substantial
duction
was
observed
together;
and
in
cultures
these
correlated
P815 presence quantities
cells
OPN
with a cultured or absence of nitrite
cytotoxic. in target
by
able 30-35%.
both
cell
the
cytolytic
Inhibition LPS
this
P815
X
10
has
recently in macro-
form
macrophages
of NOS kill
some
is OPN.
and
cytotoxicity
known to be synthesized as by macrophages [i , 5, to facilitate tumor growth
The present in blocking toward
cells,
by
the
studies demonmacrophage NO
NO-sensitive
suppressing
target,
the
increase
in
100
to U)
4) U 0
0
NO pro-
E C
used
4,
action
4.’ .
z
negligible cells). As
observed with NO production (Fig. 4), preincubation of OPN with anti-OPN antiserum for 1 h at room temperature prior to addition to macrophage-P8i5 cocultures, largely reversed the inhibition of cytotoxicity. The data are presented in Figure 7. Neither affinity-purified anti-OPN antiserum nor preimmune serum alone at the concentrations used had any obvious effect on cytotoxicity (or NO
Rollo
Whereas
substance
mastocytoma
NO production. and IFN-y, in the
produced
review].
secreted
production
was with
were
NO
production
by a cytokine-inducible
for
and metastasis [17, 18, 36]. strate that OPN is effective
of cytotoxicity in
X-100, nmol/1.5
and
IFN-’y
NO
and was
or IFN-y
killing
killing,
by a rat colon carcinoma line of a substance that suppressed cytokine-induced NO production by a rat brain microvessel-derived endothelial cell line [35]. We suggest
of cytotoxicity in NO produc-
and
to reduce
34
The
these responses with IFN-y than
LPS
15-20% decrease with or without of Triton (0.2-0.4
LPS
amount increase
to inhibit treated
when was
16 h later.
of either
modest fourfold
of OPN in cells was not increase
assayed
6. In the absence of LPS minimal and cytotoxicity
addition
the cultures induced a ( 15%) and an approximate tion. more
were
are shown in Figure NO production was
is regulated ref.
cell
attention.
OPN is a ubiquitous cytokine by various tumor cells as well 13]. In tumor cells, it appears
The effect of OPN on RAW264.7-mediated cytotoxicity toward P815 mastocytoma cells was next examined. Macrophages were stimulated with LPS and/or IFN-y for 8 h. Target cells were then added at an E:T ratio of 3: 1 and cytotoxicity
tumor
macrophages
tumor cell targets quite effectively by secretion of NO, other tumor cells are able to avoid or escape cytotoxicity [22-24]. The reason for this differential responsiveness is
that
Effect of OPN on macrophage-mediated cytotoxicity toward P81 5 mastocytoma
in
from
unknown but may be due to the release of inhibitors by the tumor cells. Murata et a!. recently reported the secretion
preimmune or preim-
for inhibiting
(Student’s
and
(b) of OPN.
antibodies
experiments
most
inhibition
with
(a, control) OPN
either
alone. NO
stimulated
absence
to determine on
on OPN-mediated
were
h in the
c and
and
serum
calibrated
of
for8
temperature
serum
antibodies
[see
-Q’,
released
considerable
phages q
c
mediators
et al.
OPN
0
10
20
30
40
Time Fig.
5.
with
LPS
were
activated
with
or presence were collected
of 1.0 and
inhibits
Time
course
and
IFN-’y
induction
of NO in the 100 pM the
production
presence
U/mL OPN. nitrite
of iNOS
At the content
60
70
80
cells
stimulated
(hours) by RAW264.7
or absence
IFN-yand
and
50
100
ofOPN.
RAW264.7
ng/mL
LPS,
indicated time determined.
points,
macrophage
in the
cytotoxicity
cells absence
supernatants
401
(A)
production
of NO
and cytotoxicity in RAW264.7 macrophages was in response to very low concentrations of OPN,
Inhibition
observed and ap-
peared >‘
80
ti
70 60
0
50
>% U
that
40
20
iNOS
0 18
14
U
12
‘4
I E
6
4
4..
:
0
LPS
IFN-y
--
-
rOPN
-+
-+
6. OPN-induced
absence the
++
--
100
ofO.1 P815
LPS
mastocytoma Data
and/or
presented
medium
from
the
mulation
of nitrite.
Samples
Cr release
assay.
.-+
-+
killing
synthesis.
A
NO
production
and
types. Consistent of the iNOS
NO-mediated
U/mL ratio
the
were
of3:1.
of
collected
were
or
5tCr-la-
hours
action of OPN was maximal at 6-8 to previous reports of the time course
induction
in macrophages production and by our findings
[22].
That
samples
RAW264.7 inhibition
the inhibi-
cytotoxicity were due to that antibodies to OPN
cells were was observed
seen with the presence of OPN
preof
on NO
transient. Thus, at 6-8 h, by 48 h
of nitrite in the culture supernatants were similar in and OPN-treated cultures. Nevertheless, this inhiwas sufficient to reduce cytotoxicity and NO producby
the
macrophages.
These
data
suggest
that
a
assayed
and
was
our
observation
that
there
is a 10-fold
dif-
are of
for the
accu-
those
taken
after
Of note
and
(B) Samples
immediately
in a 50%
h, of
damage in areas of inflammation. OPN synthesized by tumor cells may function as a defense against macrophagemediated destruction [26].
later
in Materials
experiments.
in (A)
presence with
Sixteen
triplicate
separate
or treated
in the
cultured
as described
mean
three
NO production
untreated
IFN-y were
ef-
with an inhibition gene is the finding
produce OPN. OPN produced by macrophages and fibroblasts may function as an autoregulatory molecule limiting cytotoxic mediator release and thus reducing tissue
and
cells,
OPN,
at an E:T
experiments
for the
++
determined
are from
++
cell
100
human was
of results
-
of tumor
cells,
cytotoxicity
representative culture
ng/mL
++
--
(A) RAW264.7
pM recombinant
percentage
Methods.
inhibition
RAW2#{212}4.7 cells.
for 8 h with
mRNA
transient increase in the local concentration of cytokines like OPN may be important in the regulation of macrophage activity. Appropriately stimulated fibroblasts and macrophages as well as tumor cells have the capacity to
2
beled
gene
tion
by stimulated
block
tory effects of NO OPN is supported
levels control bition
0
Fig.
may
production whereas
10
‘5
of iNOS
abrogated its action. The partial inhibition immune serum (Fig. 4) may result from OPN in normal serum. Kinetic studies revealed that the effects
16 Cl)
2
OPN
that the inhibitory which corresponds
*
10
-ii
IFN-y-induced
to inhibition
fects in a variety of cell by OPN of transcription
30
(B)
to be due
and
similar reduction in iNOS mRNA synthesis by OPN has been described in kidney proximal tubule epithelial cells, where it was shown that the inhibition was at least in part at the level of transcription [25, 40]. These results suggest
‘4
4.,
of LPS
4.. U ‘4
0
iNOS mRNA diators. This
abundance suggests
targets
macrophage-mediated
ing (TGF-)
from the
synthesis has
NO synthesis However, the
of
also
induced that OPN NO.
been
by the inflammatory may protect certain destruction
Transforming
reported
and cytotoxicity in mechanism underlying
0
4.. 5% U
by inhibitgrowth
to inhibit
4.,
metumor
the
factor-3
induction
macrophages the actions
of
[37, 38]. of TGF-
OPN
and OPN are distinct; TGFacts by up-regulating arginase activity, depleting the cells of the substrate for the iNOS enzyme [37, 38]. Taurine chloramine has also been reported to abrogate the induction of iNOS mRNA in RAW 264.7 cells by LPS and IFN-?, possibly by interfering with the synthesis of a protein scription of the iNOS gene
402
Journal
of
Leukocyte
required
for
the
increased
tran-
Preimmune Fig.
7.
anti-OPN
Volume
60,
September
1996
Reconstitution antibodies
P
0.05
-
+
-
+
-
-
-
+
+
-
-
-
-
-
-
+
+
of cytotoxicity before
carried out as described OPN was preincubated antiserum.
[39].
Biology
Anti-OPN
addition
by to cultures.
preincubation Cytotoxicity
in Materials and Methods for 1 h with either preimmune (Student’s
1-test).
except serum
+
of OPN
with
assays
were
that 0.1 pM or anti-OPN
ference in the concentration of OPN required to inhibit NO production and cytotoxicity in RAW264.7 cells. Thus, whereas cytotoxicity was blocked by 0.1 pM OPN, i pM was required to maximally inhibit production of NO by RAW264.7
cells.
cytotoxicity P815 cells.
assays In this
The
reduced
requirement
may be due regard, Feng
for
to production et a!. [36]
OPN
in
of OPN by have reported
that OPN expression by tumor cells is inversely correlated with resistance to macrophage-mediated killing and tumor cell survival. These data, together with the present findings, provide evidence to support the hypothesis that OPN can function to protect struction by macrophages. tects
tumor
stimulating ing focal [Lopez
cell
targets
cells from nonspecific process by which OPN
is unknown.
the phosphorylation adhesion kinase and and
Denhardt,
that OPN may ing to inhibition inhibit
tumor The
unpublished
NO-induced
OPN
Further
studies
depro-
is capable
results].
apoptosis the
P815
cells
[41].
with
necessary
some
aspect
to explore
of this these
research
Institutes Cancer
was
and
Oxide
Production
by Recombinant
tial fulfillment gers University,
11.
regulated
supported the the
by grants Nicholas Bureau
of
the
C. Palczuk Biological
S. Rittling
and
This report E. E. Rolbo and Human
H.
Passmore
is taken entitled
for a critique from
the
Inhibition
of
Macrophage-Mediated
and
Osteopontin
of the requirements New Brunswick,
for
presented a Ph.D.
19.
20.
21.
Nitric 23.
in parfrom
24.
Rut-
NJ. 25.
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