hal cell migration and angiogenesis in vivo in mice. Studies on proteinases ... assay in the presence of 2% FBS. The extent of tube formation by endothelial cells ...
Vol. 9, 305-312,
April
Cell Growth
1998
Inhibition of Angiogenic Differentiation Vein Endothelial Cells by Curcumin1
Deepa Thaloor, Anoop K. Singh, Paruchuri V. Prasad, Hynda K. Radha K. Maheshwari2
Gurmel
S. Sidhu,
Kleinman, and
Center for Combat Casualty and Life Sustainment Research, Department of Pathology, Uniformed Services University of Health Sciences, Bethesda, Maryland 20814 [D. T., A. K. S., G. S. S., P. V. P.,
R. K. M.]; Birla Institute of Technology
and Science, Pilani, Rajasthan,
India 333031 [D. T., A. K. S.]; and National Institute NIH, Bethesda, Maryland 20892-4370 [H. k. k.]
of Dental
Research,
Introduction Angiogenesis, the process leading to neovascularization,
Umbilical
development, reproduction, tissue and organ growth, and wound healing (1). Uncontrolled angiogenesis is pathological and is often associated with conditions such as arthritis, psoriasis, diabetic retinopathy, hemangiomas, inflammation, or atherosclerosis (2, 3). Angiogenesis is a crucial step in the growth and metastasis of cancers (4), and increased tumor angiogenesis has been associated with an increased mcidence of distant metastasis (5). The identification of agents that
Abstract Angiogenesis is a crucial step in the growth and metastasis of cancers. Curcumin inhibits tumor initiation and growth. We analyzed the effect of curcumin on endothelial cell migration, attachment, and tube formation on Matrigel. Curcumin had no effect on endothelial cell migration or attachment to either plastic or Matrigel. Curcumin treatment resulted in a dose-dependent inhibition of tube formation when the cells were treated before plating or at the time of plating on Matrigel. Curcumin treatment also caused the preformed tubes to break down. Curcumin inhibited angiogenesis in a s.c. Matrigel plug model in mice. The role of metalloproteinases has been shown to be important in angiogenesis; therefore, zymography was performed to determine whether curcumin affected protease activity. Zymographs of curcumintreated culture supernatants showed a decrease in the gelatinolytic activities of secreted 53- and 72-kDa metalloproteinases. Western and Northern analysis showed a dose-dependent decrease in the protein expression and transcript of 72 kDa, indicating that curcumin may be exerting its inhibitory effect at both the transcriptional and posttranscnptional level. These findings suggest that curcumin acts as an angiogenesis inhibitor by modulating protease activity during endothelial morphogenesis. Curcumin could be developed as an antiangiogenic drug.
of Human
& Differentiation
can
inhibit
angiogenesis
is of great
clinical
importance.
Several neutral MMPs3 seem to be involved in matrix dogradation (6). MMPs have been implicated in a variety of disease processes such as tumor metastasis, tumor angiogenesis, and rheumatoid arthritis (7). The activities of the protemnases are regulated by various mechanisms including their secretion in the zymogen form, regulation at the level of gene expression (8, 9), and modulation of their activities by specific inhibitors, namely, tissue inhibitors of metalloproteinases (1 0, 1 1). Recently, Schnaper et a!. (1 2) have shown that a decrease in the gelatmnolytic activities of both the 72and 92-kDa metalloproteinases was associated with a decrease in tube formation by endothelial cells, whereas an enhancement of activity increased tube formation. Curcumin (diferuloylmethane), a major component of the food flavor, turmeric, has been isolated from the rhizomes of Curcuma longa. Curcumin has been widely used for centuries in indigenous medicine for the treatment of a variety of inflammatory conditions and other diseases, and its nontoxic effect has been demonstrated (1 3). The anticarcinogenic properties of curcumin in animals have been demonstrated by the inhibition of tumor initiation induced by benzo(a)pyrene and 7,12-dimethylbenz(a)anthracene (14, 15) and tumor promotion induced by phorbol esters (1 6) on mouse skin and on carcinogen-induced tumorigenesis in the fore stomach, duodenum, and colon of mice (1 7). Curcumin suppresses mitogen-mnduced proliferation of blood mononuclear cells, inhibits neutrophil activation and mixed lymphocyte reaction, and also inhibits both serum-induced and plateletderived growth factor-dependent mitogenesis of smooth muscle cells (18, 19). Curcumin has been shown to inhibit 1 2-O-tetradecanoylphorbol-13-acetate-induced
of generating new blood vessels is essential during embryonic
Received 5/29/97; revised 1/28/98; accepted 2/2/98. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 1 8 U.S.C. Section 1 734 solely to mdicate this fact. 1 Supported by Naval Medical Research and Development Command Grants G1 74FQ and G174HD. 2 To whom requests for reprints should be addressed, at Center for Combat Casualty and Life Sustainment Research, Department of Pathology, Uniformed Services University of Health Sciences, Bethesda, MD 20814. Phone: (301) 295-3394/3497; Fax: (301) 295-1640.
progres-
sion of epidermal cells through the cell cycle (19). Curcumin has been reported to be a partial inhibitor of cellular protein kinases (20, 21). Based on these pleiotropic biological activities of curcumm, we studied its effect on angiogenesis in an in vitro model using HUVECs on Matrigel and in vivo in the s.c. Matrigel plug
model.
Data
reported
in this
study
show
that
curcumin
The abbreviations used are: MMP, matrix metalloproteinase; HUVEC, human umbilical vein endothelial call; ECGS, endothelial cell growth supplement; FBS, fetal bovine serum; NEM, N-ethyl maleimide; PMSF, phenylmethylsulfonyl fluoride; SSPE, saline-sodium phosphate-EDTA. 3
f’
3
Curcumin
Inhibits
Angiogenesis
Curcumin (jiM)
0
1
5
10
25
with
higher
25)
resulted
of curcumin
(1 0 and 25 M;
in decreased
tube
2O5kD-
with
forming
serum
assay
concentration,
we
in the presence
Fig. 2A, 10 and
formation,
and
appeared to be thin and incomplete. To check whether the effect of curcumin varies
ll6kD 9OkD 66kD-
doses
(22). The effect
on tube formation the tubeThe extent of tube
of 2% FBS.
of curcumin
tubes
performed
formation by endothelial cells in the presence when compared with 1 0% serum is only about
-
the
treatment
of 2% serum half-maximal
on tube formation
in
45kD-
the presence of 2% serum is shown in Fig. 2B. An inhibitory effect on the network formation could be seen with as little as 1 p.M curcumin, although the maximal effect was observed at 10 p.M curcumin, where there is complete inhibition of tube
26kD-
formation. Treatment with a lower concentration (5 ).LM) resulted in incomplete and sparse tube
2B, 5). Because against
14.2kD
-
evidenced
-
serum
the inhibitory
seems
effect
by an earlier
of curcumin formation (Fig.
to have a protective
on tube
formation
experiment,
effect
by curcumin
we used
as
medium
con-
2% FBS in all additional experiments. Effect of Curcumin Treatment at Different Times on Tube Formation. We investigated whether curcumin-induced inhibition of tube formation is reversible. HUVEC cells taming
Fig. 1. Protein synthesis in curcumin-treated cells. The autoradiogram shows the metabolic labeling of HUVECs. HUVECs were treated with various doses of curcumin and labeled with r5S]methionine. The proteins were analyzed on 10% polyacrylamide gels containing SDS by gel electrophoresis. The arrows indicate the proteins inhibited by curcumin at a concentration of 25 )LM.
had
no effect
inhibited
on cell
tube
manner.
migration
formation also
Curcumin
and
on
attachment.
Matrigel
inhibited
ity and expression
Curcumin
ECGS-stimulated
of the 53- and 72-kDa
Studies on the activ-
metalloproteinases
on plastic and Matrigel (data assay showed that curcumin
nificant
on the migration
control
assay
(data
not
shown);
used in this study to
curcumin
HUVECs (1-10
block
with
the
j.LM) did
not
chemotaxis.
inhibit
proteins)
curcumin
(Fig.
Curcumin ment the
was
of proteins
in the
Capillary
Tube
with
of plating
varying
on
doses
Matrigel
60-, 36-, and of 25 j.LM
In the
14).
entiated to form 0). Lower doses the differentiation were
presence
an extensive of curcumin of endothelial thinner
than
Formation.
of curcumin
in medium
tion
tubes
of
of proteins
presence
(1-25
of 10%
FBS,
untreated
(Fig. 14, controls.
that
tube
HUVECs were
1 and
treatment
by 75%
Treatment
from the formation,
with
on Matrigel
various
but
with
[Fig. 3A, a (1 (10-25 [Fig. 3B, a
cell culture indicating
did that
for 6 h, and then the tubes
concentrations
of curcumin.
did not significantly affect the almost 6 h after its addition. However, treatment resulted in the disintegration
preformed thereafter of the
Cur-
tubes for curcumin preformed
tubes in a dose-dependent manner (Fig. 3A, b). Prolonged incubations of HUVECs on Matrigel resulted in the thickening of tubes that underwent further remodeling [Fig. 3B, b (0)]. Treatment of the tubes with 1 MM curcumin did not show much change in the preformed tubes [Fig. 3B, b (1)1, whereas treatment
and
the
were
formation
vessels
p.M
[Fig.
curcumin
tubes
that
Treatment
tubes
with
by almost
80%
3B,
seemed
b (5,
to lack
25 p.M curcumin
(Fig.
3A,
dis-
and
b),
10,
interthe
to shrink.
Inhibits
curcumin
iments
25
in broken
communication.
seemed
cause sel
5, 10, and
with
25) resulted
Curcumin
10%
5),
were plated
treated
tubes
differ-
the
1 p.M curcumin
whereas
formation
of
inhibited
with
tube formation,
inhibited
pretreatment
effect of curcumin on tube formation was irreversible. To determine the effect of curcumin on preformed tubes,
p.M) at
of tube formaHUVECs
for
and the cells were
.LM) significantly
and 25)]. Removal of curcumin prevent the inhibition in tube
integrated
network of thick tubes (Fig. 2A, (1-5 (.LM) did not markedly affect cells
showed
(5-25
(Fig. 3A, a). Pretreatment
curcumin
Treat-
containing
inhibition
analysis
curcumin
incomplete
cellular
in a dose-dependent
the
of
that curcumin
(including
inhibited
FBS resulted (Fig.
migration labeling
or type
of curcumin
concentrations
off with media,
cumin
1).
Reduces
of HUVECs time
compared
cell
Metabolic
amount
not shown). had no sig-
test the ability
demonstrated the
the
inhibit
there was a small decrease in the cells were treated with 25 MM curcu-
mm (Fig. 1). The synthesis 30.7-kDa
the
various
and 5)]. However, curcumin at higher concentrations LM) completely inhibited angiogenic differentiation
not
when
not formally
[35S]methionine
synthesized; however, protein synthesis when
of cells however,
does
could
Cell Attachment, .LM) did
with
formation
5 M
not
the cell attachment The cell migration with
tube
(10
Results Effect of Curcumin on Cell Migration, and Protein Synthesis. Curcumin (1-25
with
was washed
Quantitative
HUVECs
showed
of HUVECs. The inhibition of angiogenesis by curcumin be partly due to the inhibition of the metalloproteinases.
difference
times.
endothe-
in mice. inhibited
pretreated
3 h. Curcumin
counted and plated on Matrigel. Pretreatment of cells for 3 h with curcumin before plating cells on Matrigel seemed to be the most effective, as compared with all other treatment
in a dose-dependent
hal cell migration and angiogenesis in vivo proteinases demonstrated that curcumin
were
Angiogenesis
inhibited performed in
vivo.
in
the tube to determine
in Matrigel plugs containing plugs containing ECGS
showed
a significant
decrease
(P
cells
0.0035)
it inhibits
invade
angiogenic and 25 =
in Mice. Beexper-
in vitro,
whether
Endothelial
Matrigel
Vivo
formation
tM
and
yesform
factors (23). curcumin
in the number
of
Cell Growth & Differentiation
Cur. (riM)
0
1
5
10
X7
25
A
B
\
..
Fig. 2.
Inhibition
of tube
Matrigel-precoated dose-dependent
cells
formation
by curcumin.
HUVECs
(4 x lO4celIs/well)
in the plugs
compared
to plugs
containing
EGGS
alone;
however, at the lower concentrations of curcumin, no significant difference was observed in the migration of cells (Fig. 4A). H&E staining of the Matrigel plugs containing ng/ml) showed that a large number of endothelial grated small
curcumin were that curcumin
the
EGGS (100 cells mi-
into the plug and formed tubes (Fig. 4B, top panel). A number of cells in the plugs containing EGGS and
formation
observed inhibited
(Fig. 4B, bottom panel), indicating the migration of cells and vessel
in vivo.
Curcumin
Blocks
effect
of curcumin
graphic
in medium
assay
Proteinase
Expression.
on proteinases,
to visualize
we
the proteinases
To determine used
a zymo-
expressed
by HU-
change
in the activity conditioned
data
However,
buffer containing ity was observed
when and
the
incubated
supernatants with
of
proteases.
of the proteolytic various
protease
buffer. cellular
Results (Table 1) indicate proteinases in HUVEGs
certain of gels
metalloproteinase in the presence
activities inhibitors
was further
probed
in the gel incubation
that the activities of extraare specifically inhibited by
inhibitors. of NEM and
or the
curcumin-
to incubation
in
is required
,
suggest
that
the presence for activating the
of divalent
cations,
regulated
these
by curcumin
Western treated
cumin
using
antibodies
showed
a reduction
pendent
on the dose
monoclonal
We did not further because
it was
of the
anti-72-kDa 72-kDa
of curcumin pursue expressed
such
metalloproteinases,
proteinases
proteinase (Fig.
the work
of in
analysis with cur-
that
also was
de-
6).
on the 53-kDa
at a very
low
level.
proteinNorthern
analysis showed that curcumin inhibited the RNA transcripts of 72-kDa proteinases in a dose-dependent manner (Fig. 7), indicating that curcumin inhibited 72-kDa proteinase accuat the transcriptional
level.
substrate
curcumin, no inhibition of proteolytic activ(data not shown), suggesting that curcumin
to the secreted
the control as compared
belong to the class of metalloproteinases. of 72-kDa proteinases in endothelial cells
mulation
5).
zymographed
of either medium
Because
groups.
(Fig. were
The identity
2% serum (B) were plated on Curcumin treatment resulted in a
both
as Ga2
proteinases
by including
(A) and
buffer containing calcium alone, the addition completely inhibited the proteolytic activities
ase
not bind
serum
the substrate EDTA or DII
on plastic in the presence of 2% FBS after 6 h with different doses of curcumin. HUVEGs sethe 53- and 72-kDa proteases. Gurcumin (10 the gelatinolytic activities of the 53- and 72-kDa
did
10%
treated
VECs grown of treatment creted both p.M) inhibited HUVEGs
containing
24-well plates and treated with curcumin (0-25 )LM). After 6 h, the cultures were fixed and stained. inhibition of tube formation. Numerals above the panels represent the concentration of curcumin.
Whereas the incubation PMSF did not show any
Discussion Angiogenesis is a highly regulated process that involves a complex cascade of events. Given the physiological and pathological importance of angiogenesis, extensive studies have been carried out to identify the factors that regulate this process. A number of growth factors, such as fibroblast growth and
factor
tumor
(24),
necrosis
vascular factor
endothelial a (26), stimulate
growth
factor
angiogenesis
(25), in
308
Curcumin
Inhibits
Angiogenesis
A C
0 .
120 100
0 .
80
80
a)
a)
60
60
a)
a)
a)
40
a)
20
a) Q.
120 100
a) a)
40
C
a) 0
20
a)
a.
0 0
1
5
Curcumin
10
0
25
0
(pM)
1
5
Curcumin
a
10
25
(pM)
b
B Cur (pM)
0
1
5
10
25
a
b
Fig. 3. Effect of pretreatment versus posttube treatment on tube formation by curcumin. A, the difference in tube area between cells cultured in media alone containing 2% serum compared with those cultured with curcumin (1-25 ).LM). a, HUVECs were treated with varying doses of curcumin (0-25 M) for 3 h. After treatment, the cells were washed with PBS, and 4 x 1 O’ cells/well were plated in triplicate on Matrigel-coated 24-well plates. b, preformed tubes were treated with curcumin (0-25 MM), and tubes were fixed and stained after 12 h. The effect on tube formation was quantitated by scanning the pictures after fixation and staining using the NIH Image program. Data points represent the percentage of the average length of the tubes in three random fields of quadruplicate with + SE. *, P < 0.001 significant difference from media alone (Student’s t test). B, representative pictures of tubes formed in the presence and absence of curcumin (a, pretreated; b, posttube treatment). Numerals above the panels represent the concentration of curcumin.
vivo.
In view
of the therapeutic
value
of angiogenic
inhibitors,
some angiostatic compounds including medroxyprogesterone acetate have been identified (27-29). Because curcumin has been reported to inhibit tumor initiation (14, 15) and
tumor promotion mm on angiogenic model model.
and
vessel
(1 6), we investigated the effects of curcudifferentiation using an in vitro Matrigel formation
using
an in vivo
Matrigel
plug
Cell Growth & Differentiation
309
A 2O
Ji
‘15
T
‘I
,1o
z5
Hfl
o
io
is
(M)
Curcumin
B
Control
Curcumin
Curcumin inhibits angiogenesis in vivo in the s.c. Matngel assay. A, graph showing the results of three in vivo experiments expressed as the number of cells that migrated ± SE in three microscopic fields for each s.c. Matrigel plug. Fields were equidistant from the edge of the plug. *, P = 0.0035, a significant difference from ECGS alone (Welch’s t test). B, histological sections of Matrigel plugs. Top panels, 100 ng/ml ECGS (positive control); bottom panels, 1 00 ng/ml ECGS and 25 M curcurnin. These section shows the two extremes observed in both treatments. Fig. 4.
Nontoxic and
doses
protein
ferentiation
The the
pretreating
effects
inhibited
cells
may
of HUVEGs with
the
drug
cell viability
angiogenic
in a dose-dependent
of curcumin
differentiation the
that did not affect
significantly
HUVECs
of
Matrigel. cause
of curcumin
synthesis
inhibit
angiogenesis
dif-
higher
than
on
serum.
manner
be irreversible,
be-
is still
inhibited
after
then
washing
them
and
plete
inhibition
was
a higher
inhibition
when
Matrigel,
suggesting
differentiation. curcumin
incubation
cells The
depends
medium.
observed
at
concentration were
treated
that
early
inhibition
a lower
concentration,
was required genes
may
of angiogenic
on the serum
The effective
for complete
at the time
concentration
be
on
involved
in
concentration
by in the
required
to
serum
is much
presence
of 2%
shown a serum-dependent on Matrigel. The mechanism
in tube formation
of curcumin
seems
in angiogenic
to require
3-6
h of incubation
that curcumin did cascades affecting
on Matrigel
involves
attachment, migration, and the productionof ble of modifying the extracellular process. cell attachment
ously
that
curcumin
with
not act dithe steps
differentiation.
oftubes
affect
of
with regard to how it binds to the cell and at the cellular level is not known. The
endothelial cells, suggesting rectly. It may induce signaling The formation
of 1 0%
to do so in the
et a!. (22) have
its effects
effect
presence
required
of curcumin
involved
of plating
differentiation present
action
induces
extensively before plating on Matrigel. In fact, pretreatment is more effective in preventing tube formation, because comwhereas
Kinsella
difference
in the
that
and
migration.
inhibits
cell
endothelial enzymes Gurcumin
We have
proliferation
shown
cell capadid not previ-
in a dose-de-
310
Curcumin
Inhibits
Angiogenesis
Serum
0
1
5
10
25
Table
1
Characterization
of the proteinases
Control
EDTA
DTT
PMSF
NEM
Proteinases C -72kDa -53kDa
92 kD---
72 kD-
---.--
.----
a
.
Conditioned
cumin
was
Methods.”
53 kD-
Cur
C
Cur
C
Cur
C
Cur
C
++
+
-
-
-
-
++
+
++
++
+
-
-
-
-
++
+
++
medium separated
from
HUVECs
on
SDS-PAGE
After electrophoresis,
treated
with
or without
as described
pendent
manner
the
(30).
hypothesis formation
that inhibition by endothelial
of MMP-2 activity decreases cells, suggesting that curcumin
duced a decrease in MMP-2 that led to the inhibition formation. Furthermore, we have seen that curcumin inhibit from
the
proteolytic
untreated
cells
activity were
when
without
significantly
affecting
the viability
of
the
incubated
media
that the effect of curcumin to the regulation of metal-
is probably
tumor growth and prevent and clinical applications
on the
Matrigel
on Matrigel
therapeutic
do not
proliferate
differenti-
molecules
to cell cycle
secondary
ated tubes
effect
before
of curcumin
tube
by curcumin
therefore,
was added after the completion of in angiogenesis. This may be due
of remodeling
by curcumin, of tubes. differentiation
the
extent
of angiogenesis
in vivo
work
vessels
of fully
to the disintegration inhibited angiogenic
examined
Previous
HUVECs
disintegration
may not also be related
curcumin involved
to the modulation mately leads Gurcumin
formation.
(31). The
events, because the initial events
on mitogenesis
has shown in Matrigel
inhibition
in a Matrigel that plugs
plug
which in
endothelial
cells
containing
in mice.
angiogenic
and
factors
(23). Gurcumin inhibited the endothelial cells’ infiltration and vessel formation in the plugs, indicating that curcumin possess antiangiogenic activity in vivo. These results support the observation
vitro
Gurcumin
that
could
which
as antiangiogenic
is easily attainable
is the
reorganization and
inhibitors
role
angiogenesis pression
in matrix
atm
zymography. pression of the
demonstrated
53-kDa
that
monoclonal
ase inhibited
curcumin anti-72-kDa
tube formation
in a dose-dependent proteinase,
play a major
and
differentially
the
initiation
regulated
proteinases
as revealed
Gurcumin induced a decrease 72-kDa protein, and the mRNA
ase at both the transcriptional
MMP-2
manner, (12). The
ma-
assembled
secreted glycoproteins and indicate that metalloprotein-
of metalloproteinases
regulated
the
by gelin the oxtranscript
72-kDa
gelatinase/type
by endothelial suggesting results
of
the ox-
protein-
and posttranscriptional
level.
IV collagen-
cells on Matrigel the role of 72-kDa
are consistent
with
Based
potential
been
hampered
angiogenesis
metasof such
by the
without
lack
of
undesired
on the
antiangiogenic
further
for the development
property,
of a
and
Methods
Material. HUVECs were purchased from Clonetics, Inc. (San Diego, CA). Media-199, streptomycin, penicillin, gentamicin, fungizone, and 0.05% trypsmn-EDTA were obtained from Life Technologies, Inc. (Gaithersburg, MD). ECGS was purchased from Collaborative Research, Inc. (Bedford, MA). FBS was obtained from Hyclone Laboratories, Inc. (Logan, UT). Curcumin, DMSO, heparin, L-glutamine, PMSF, NEM, and DTT were pur-
chased from Sigma Chemical Co. (St. Louis, MO). Rabbit antifactor VIII lgG was obtained from DAKO Corp. (Carpinteria, CA). Monoclonal antihuman
MMP-2
was purchased from Oncogene Sciences (Cambridge, antirabbit lgG was purchased from Organon Teknika (Durham, NC), whereas goat antimouse lgG conjugated to alkaline phosphatase was obtained from Bio-Rad (Hercules, CA). Culture of HUVECs. Cultures of HUVECs were maintained in media199 supplemented with 2-10% FBS; 100 g.g/rnl ECGS; 100 units of penicillin, streptornycin, and fungizone; 50 mg/mI gentarnicin; and 50 units/mI heparin in 5% CO2 and 95% 02 at 37”C. All experiments were carried out between passages three and seven. Cells were checked periodically for the expression of factor VIII by immunofluorescence.
MA). FITC-labeled
drug, bein vivo (32).
network
reorganization
(12). Gurcumin
of 72- and
formation.
of the extracellular
dynamic
outside of the cell using specific proteoglycans. Recent reports regulatory
tube
concentration
is a complex
ases and tissue
inhibited
be developed
cause its effective Remodeling
curcumin
effects.
could be studied anticancer agent.
curcumin
Materials
vitro;
invade
have
to inhibit
one of the most prom-
ulti-
by curcumin model
strategies
able
of tube did not buffers
ising strategies to restrict tasis. The development
The
tube in-
conditioned
not explain the inhibition of angiogenic differentiation when the cells were treated before plating or at the time of plating
Mouse
and
with
in substrate
loproteinase expression. Antiangiogenic therapy
trix,
cur-
jLM
overnight
could
cells
in
+
25
in “Materials
the gels were incubated
containing curcumin, suggesting on angiogenesis may be related
form
+
either substrate buffer (control) or buffer containing EDTA (1 0 mM), DII (5 mM), PMSF (1 mM), or NEM (5 mM). The gels were stained and visualized. The presence of activity is expressed as + ; the absence of proteolytic activity is expressed as - . C, untreated; Cur, treated with 25 M curcumin.
Fig. 5. Zymogram analysis of the gelatinolytic activities. Conditioned medium of HUVECs treated with curcumin (0-25 j.M) was harvested after 6 h and subjected to a nonreducing SDS-PAGE through a 1 0% acrylamide resolving gel containing gelatin as described in “Materials and Methods.” The gels were incubated in the substrate buffer overnight at 37”C and stained with Coomassie Blue. Gelatinolytic activity is indicated by bands in the gel at 92, 72, and 53 kDa. Lane 1, 2% serum; Lanes 2-6, curcumin. Numerals on the lanes represent the curcumin concentration.
was
Cur
the
Cell Attachment Assay. This assay was performed previously (33). HUVECs (4 x 1O cells/well) were plated in on either BSA-precoated 24-well plates or Matrigel, and added at a final concentration of 0, 1 , 5, 10, or 25 M. After either 2 h on plastic or 45 mm on Matrigel, the supernatant
and the cells were fixed and stained
as described four replicates curcumin was incubation for was aspirated,
using Duff-Quick (Baxter Scientific
Products, McGraw Park, IL). Metabolic Labeling of Cells with (S]Methionine. HUVECs were plated overnight on plastic in media-i 99. After 24 h, the cells were washed with rnethionine-free media and incubated for 2 h with methionine-free media containing 2% dialyzed serum, r5S]methionmne (2 Ci/d), and curcumin (1-25 LM). Medium was replaced with regular medium containing curcumin (i-25 j.M), and the cells were incubated for an additional 7 h. The cells were washed with PBS, and the lysate was prepared in radio-
Cell Growth
Curcumin pM
0
1
5
Cu rcu m In iM
1025
0
5
1
& Differentiation
10
25
72kD
.1
72 kD Fig. 6. Western analysis of the 72-kDa proteinase. protein from culture supernatants of HUVECs treated jiM)
for 6 h were separated
on 10% SDS-PAGE,
Equal amounts of with curcumin (0-25
transferred
lulose membrane, and probed with monoclonal anti-72-kDa bands were developed with alkaline phosphatase-conjugated
lgG and 5-bromo-4-chloro-3-indolyl
phosphate/nitroblue
immunoprecipitation assay buffer containing proteinase proteins were analyzed on 10% acrylamide SDS-PAGE.
to a nitrocelantibody. The antirnouse tetrazoliurn.
inhibitors.
The
Cell Migration Assay. Cell migration was measured as described previously (34). Two 2-mm scratches were made in each well of a 6-well plate containing confluent HUVECs using a modified rubber cell scraper. The wells were rinsed, and 1 .5 ml of complete medium containing 0, 1 , 5, 10, or 25 LM curcumin or basic fibroblast growth factor (10 ng/mI) were added as a positive control. After 24 h of incubation, two additional
scratches were made as reference marks, the medium was aspirated, and the cells were fixed and stained using Diff-Quick. Cell migration into the scratched area was evaluated by counting the calls under an inverted phase microscope. Angiogenesis
Assay.
Twenty-four-well
with 0.3 ml of Matrigel (14-20 solidify
at 37”C
for 1 h. Media-199
added to the Matrigel-coated
culture
mg protein/mI), (250 l)
plates
were
coated
which was then allowed to
containing
2 or 10%
FBS was
wells. HUVECs were then trypsinized
using
trypsin-EDTA (Life Technologies, Inc.), washed, suspended in appropriate media, and added to Matrigel-coated wells (40,000 cells/well in 250 il of media). Various concentrations of curcumin from these stock solutions such that DMSO
were added had no effect
cell differentiation.
for 6 h at 37”C in a 5% CO2
The cells were incubated
to the culture on endothelial
humidified atmosphere, the culture supernatant was aspirated, and the cells were fixed with Diff-Quick Solution ll(Baxter Scientific Products). The area covered by the tube network was quantitated using an optical rnaging technique in which pictures of the tubes were scanned in Adobe Photoshop and quantitated in the NIH Image program. Each dose of control or test compound was assayed in triplicate. In addition, all experiments were performed at least three times, and the results are expressed as the mean and the SE from at least three such experiments.
For pretreatment
studies, 2% FBS-containing
media were added to the
cells and incubated overnight. The cells were then treated with curcumin (1 -25 M) for 3 h. After treatment, curcurnin was washed off, the cells were trypsmnized, and 40,000 cells/well of each treatment were plated in tripli-
cate on Matrigel-coated plates. Tube formation was observed after 6 h. Posttreatment studies were carried out by treating tubes formed on Matrigel for 6 h with curcumin (1-25 after 12 h, the tubes were fixed In Vivo Matrlgel Plug Assay.
SM). Tubes were observed and stained. This assay was performed
every 2 h, and as described
by Passaniti et al. (23). Briefly, Matrigel (liquid at 4”C) was mixed with 100 ng/ml
ECGS
alone
or in combination
with curcumin (5-25 p.i) and injected female mice. After injection, the Matrigel polymerized to form a plug. After 7 days, the animals were sacrificed, and the Matrigel plugs were removed and fixed in 10% neutral-buffered formaIm solution (Sigma Chemical Co.) and embedded in paraffin. Histological sections were stained with Masson’s tnchrome, and photornicrography was performed. Zymogram Analysis. Cells were treated with curcumin (1-25 M) for 6 h, and the supematants were collected for analysis of proteinase activity. SDS-substrate gels were prepared by a modification of standard SDS-PAGE electrophoresis (35). Type I gelatin was added to the standard acrylamide polymerization mixture at a final concentration of 1 mg/mI. The protein concentration in the media from cells cultivated on plastic was estimated using a protein estimation kit (Pierce, Rockford, IL). Equal protein from each sample was mixed (3:1) with sample buffer [10% SDS, 4% glycerol, 0.25 M Tris-HCI (pH 6.8), and 0.1 % brornophenol blue] and
s.c. into three or four C57B1/6N
loaded into the wells of a 4% acrylamide
stacking
gel and a 10% acryl-
amide resolving gel. Gels were run at 1 5 mA/h during stacking mA/h during the resolving phase at 4#{176}C. After electrophoresis,
were soaked
in 2.5% Triton X-iOO with gentle shaking
and at 20 the gels
for 30 mm at
28S
Fig. 7. Northern analysis of rnRNA for the 72-kDa proteinases. HUVECs grown to 75% confluence on plastic were conditioned overnight in medium containing 2% serum and treated with curcurnin (0-25 iM) for 3 h. RNA was isolated using the RNAzoI method, electrophoresed on a 1 % agarose gel, and probed with 72-kDa as described in “Materials and Methods.” Ethidium bromide-stained 28S RNA shows equal RNA.
ambient were
temperature with one change of detergent solution. The gels rinsed with water for 20 mm and incubated overnight at 37”C in
substrate buffer [50 mM Tns-HCI buffer (pH 8), 5 m CaCl2, and 0.02% Tween 20]. After incubation, the gels were stained for 1 h in 0.5% Coomassie Blue R-250 in acetic acid:methanol:water acetic acid:methanol:water (1 :4:6). After intensive
(1 :3:6) and destained in destaining, proteolytic
areas appeared as clear bands against a blue background. weights
of the proteolytic
bands
were determined
The molecular
in relation
to the refer-
ence marker proteins, which were simultaneously
loaded in the gel. The molecular weight markers were: (a) rnyosin, 205,000; (b) fJ-galactosidase, 12i 000; (c) BSA, 86,000; (c ovalburnin, 50,500; (e) carbonic anhydrase,
33,600; (1) soybean trypsin inhibitor, 27,800; (g) lysozyme, 1 9,400; and (h) aprotinin, 7,400 (Bio-Rad). To examine whether curcumin binds to the secreted proteases, the supematants of HUVECs grown on plastic were zymographed and incubated in substrate buffer containing curcumin (0, 1 , 5, 10, or 25 MM). Characterization of the Proteinases. For the characterization of pro-
teinases,
proteins
were separated
on SDS-PAGE,
and the gels were
incubated
for 1 8 h in substrate buffer containing either 1 0 mM EDTA, 1 m PMSF, 5 mM NEM, or 5 rn DTT. Characterization of proteinases was based on a comparison of the gelatinolytic activity of proteinases in the presence and absence of inhibitors. lmmunoblotting. HUVECs were plated in 6-well tissue culture plates in media-199 containing 2% serum. The cells were conditioned overnight in 2% FBS-containing media and treated with various concentrations of curcumin for 6 h. Equal amounts of protein were denatured and resolved by electrophoresis on 10% SDS-PAGE gels using standard techniques (35) and transferred to nitrocellulose filters (Schleicher & Schuell, Keene, NH) at 4”C for 4 h. Nonspecific binding was prevented by blocking in 5% nonfat dried milk for 4 h in TBST buffer [100 rn Tris-HCI (pH 7.5), 0.9% w/v NaCI, and 0.1 % v/v Tween 20]. Blots were washed three times for 15 mm each at room temperature with TBST and incubated individually with
anti-MMP-2 Blots were
monoclonal
antibody
(Oncogene
Sciences)
at 4”C for 12 h.
washed again with TBST and immersed in alkaline phosphatase-conjugated goat-antirnouse lgG (Bio-Rad), followed by washing with TBST. Immunoreactivity was visualized by the addition of nitroblue tetrazolium and 5-bromo-4-chloro-3-indoyl phosphate (Prornega, Madison, WI). Northern Analysis. HUVECs (8 x 1 06 cells) at passage five or six were plated in large 1 50-cm2 tissue culture flasks. After 1 2 h, the medium was
replaced
with fresh rnedia-199
containing
2% FBS. Cells were treated
with curcumin (1-25 .tM) for 3 h, washed with cold PBS, and lysed in TRIzol (Life Technologies, Inc.). RNA was isolated as specified by the manufacturer. Further purification of the RNA was done by precipitation with 0.3 M sodium acetate and ethanol. RNA was quantitated by measunng its absorption at 260 nm in a Beckmann DU640 spectrophotorneter. Equal amounts of RNA (10 .tg) were denatured in 6x loading buffer [0.25% w/v bromphenol blue, 0.25% w/v xylene cyanol, 30% w/v glycerol, 1 .2% SDS, and 60 mM sodium phosphate (pH 6.8)] at 75”C for 5 mm. RNA was electrophoresed on a 1 % agarose gel at 3-7 V/cm in 1 0 m sodium phosphate buffer (pH 6.8), with continuous circulation of the buffer. The
311
312
Curcumin
Inhibits
Angiogenesis
separated RNA was stained with ethidium under UV light. The RNA was then transferred
bromide
and photographed
16. Huang,
to a Nytran membrane from (Schleicher & Schuell) by the capillary method in 20x SSPE. Transferred RNA was cross-linked by UV light for 2 mm and hybridized with cDNA of the 72-kDa metalloproteinase. The cDNA was labeled with [a-32PIdCTP (Arnersham, Arlington Heights, IL) using an oligolabeling kit (Promega) and purified using nick columns (Pharmacia, Piscataway, NJ). The labeled probe (1 x lO6cpm/ml) was added to the blot that had been previously prehybridized for 8 h at 42#{176}C with the hybridization solution Hybrisol (Oncor, Gaithersburg, MD) and incubated at 42#{176}C for 16 h with the labeled
probe. The blot was washed three times with 1 x SSPE containing 0.1% SDS at room temperature and once with 0.1 x SSPE containing 0.1 % SDS for 30 mm at 50#{176}C. The blot was exposed to X-ray developed in a Kodak X-OMAT2O autoprocessor.
film for 12 h and then
M. T., Smart,
R. C., Wong,
G. 0., and Conney,
promotion in mouse skin by 12-0-tetradecanoylphorbol-13-acetate. car Res., 48: 5941-5946, 1988.
18. Srivastava, curcumin, 22: 2-6,
A., and Srimal,
a non-steroidal, 1990.
A. C. On the mechanism
anti-inflammatory
agent.
Indian
19. Huang, H. C., Jan, T. R., and Yen, S. F. Inhibitory
an
anti-inflammatory J. Pharmacol., 221: protein
Acknowledgments or assertions
contained
herein
are the private
views
authors and should not be construed
as official or as necessarily
the views of the Uniformed Services the Department of Defense.
University
of the Health
of the
reflecting
Sciences
or
kinase
agent, on vascular 381-384, 1992.
smooth
B. B. Curcumin
V. Angiogenesis.
L Hyperlipidemia DC), 193: 1044-1049, 1976.
R., and Harker,
J. Biol. Chem.,
267: cells
N. Tumor carcinoma.
and atherosclerosis.
Science
Fibrinolysis,
4 (Suppl.):
A., and Graeff, 3-26, 1992.
J. Angiogenesis
other diseases.
of proBiochim.
C regulates
kinase.
H. Tumor-associated
in cancer, vascular, , 1995.
and
in inva-
rheumatoid
and
8. Chin, J. A., Murphy, G., and Werb, Z. Stromelysmn: a connective tissuedegrading metalloendopeptidase secreted by stimulated rabbit synovial fibroblasts in parallel with collagenase. J. Biol. Chem., 260: 12367-12376, 1985.
10. Hanemaaijer, R., Koolwijk, Hinsbergh, V. W. M. Regulation human vein and microvascular
L M. TGFj31 a foe binding
inhibition of tranSin/ sequence. Cell, 61:
P., Le Clercq, L, Do Vree, W. J. A., and van of matrix metalloproteinase expression in endothelial cells. Biochem. J., 296: 803-
809, 1993. 1 1 . Herron, G. S., Banda, M. J., Clark, E. J., Gavrilovic, J., and Werb, 1 Secretion of metalloproteinases by stimulated capillary endothelial cells. II. Expression of collagenase and stromelysin is regulated by endogenous inhibitors. J. Biol. Chem., 261: 2814-2818, 1986. 12. Schnaper, H. W., Grant, D. S., Stetler-Stevenson, W. G., Fridman, R., D’orazi, G., Murphy. A. N., Bird, A. E., Hoythya, M., Fuerst, T. A., French, D. L, Quigley, J. P., and Kleinman, H. Type IV collagenase(s), and TIMP5 modulate endothelial cell morphogenesis in vitro. J. Cell. Physiol., 156: 234-246, 1993.
13. Ammon, H. P., and WahI, M. A. Pharmacology Planta Med., 57: 17, 1991.
is a non-competitive and Left., 341: 19-22, 1994.
endothelial
cell tube formation 199: 56-62, 1992.
of Curcuma
longa.
on basement
25. Pepper,
M. S., Ferrara, N., Orci, L, and Montesano, growth
factor
plasrnmnogen activator Biophys.
(VEGF)
induces
inhibitors
the plasmmnogen
Res. Commun.,
28. Li, W. W., Casey, A., Gonzales, E. M., and Folkman, J. Angiostatic steroids potentiated by sulfated cyclodextrins inhibit neovascularization. lnvestig. Ophthalmol. Vis. Sci., 32: 2898-2905, 1991. 29. Pepper, M. S., Vassali, J. D., Wilks, J. W., Schwelgerer, L, Orci, L, and Montesano, A. Modulation of bovine microvascular endothelial cells proteolytic
properties
419-434,
1994.
by inhibitors
30. Singh, inhibitsthe
A. K., Sidhu, proliferation
of angiogenesis.
J. Cell. Biochem.,
Swiss
M. A., and Bhide,
stomach mice.
Nutr.
S. V. Chemopreventive effect of turmeric induced by chemical carcinogens in 17: 77-83, 1992.
and skin tumors Cancer,
55:
G. S., Deepa, T., and Maheshwari, A. k. Curcumin and cellcycle progression of human umbilical vein cell. Cancer Left., 107: 109-1 15, 1996.
endothelial
31 . kubota, Y., kleinman, H. k., Martin, G. A., and Jawley, T. J. Role of laminin and basement membrane in the morphological differentiation of human
endothelial 1988.
calls
Into capillary-like
structures.
J. Cell
Biol.,
107:
1589-1598,
32. Khanna, M., Singh, S., and Sarin, J. P. S. The metabolic curcumin in rats. Indian Drugs, 18: 207-209, 1981. 33. Grant,
D. S., Tashiro,
and Kleinman,
of human
Cell, 58: 933-943,
endothelial 35.
Laemmli,
disposition
of
B., Yamada, Y., Martia, G. A., domains of laminin mediate the differ-
K.l., Segui-Real,
H. K. Two different
34. Pepper, M. S., and Meda, P. Basic fibroblast growth junctional communication and connexin 43 expression
15. Azuine,
and
cells. Bio-
27. Crum, A., Szabo, S., and Folkman, J. A new class of steroids inhibits angiogenesis in the presence of heparin and hepann fragment. Scienca (Washington DC), 230: 1375-1378, 1985.
zo(a)pyrene and 7,1 2-dimethyl 13: 2183-2186, 1992.
Carcmnogenesis(Lond.),
R. Vascular
26. Montrucchio, G., Lupia, E., Battaglia, E., Passerini, G., Bussolino, F., Emanuelli, G., and Camussi, G. Tumor necrosis factor a-induced angiogenesis depends on in situ platelet activating factor biosynthesis. J. Exp. Med., 180: 377-382, 1994.
entiation
benz(a)anthracene.
mem-
activators
in microvascular endothelial 181: 902-906 1991.
14. Huang, M. T., Wang, 1 V., Georgiadis, C. A., Laskin, J. D., and Conney, A. H. Inhibitory effects of curcumin on tumor initiation by ben-
against
in
24. Villaschi, S., and Nicosia, A. F. Angiogenic role of endogenous basic fibroblast growth factor released by rat aorta after injury. Am. J. Pathol., 143: 181-189, 1993.
chem. proteases.
Nat. Med., 1: 27-31
9. kerr, L D., Miller, D., and Matrisian, stromelysin gene is mediated through 261-278, 1990.
FEBS
on
3-acetate
23. Passaniti, A., Taylor, A. M., Pill, R., Guo, Y., Long, P. V., Haney, J. A., Pauly, A. A., Grant, D. S., and Martin, G. R. A simple quantitative method forassessing angiogenesis and antiangiogenic agents using reconstituted basement membrane, heparin, and fibroblast growth factor. Lab. Invest., 67: 519-528, 1992.
endothelial
angiogenesis and metastasis: correlation N. EngI. J. Med., 324: 1-8, 1991.
6. Schmitt, M., Janicke, 7. Folkman,
10931-
in inflam-
4. Moscatelli, D., and Rifkin, D. B. Membrane matrix localization teases: a common theme in tumor invasion and angiogenesis. Biophys. Acta, 948: 67-85, 1988. 5. Weidner, sive breast
of phosphorylase
brane, Matrigei. Exp. Cell Res.,
2. Pober, J. S., and Cotran, R. S. The role of endothelial mation. Transplantation (Baltimore), 50: 537-544, 1990.
(Washington
effect of curcumin
induced
22. Kinsella, J. L, Grant, D. S., Weeks, B. S., and Klelnman, H. k. Protein
References
3. Ross,
cell proliferation.
21 . Reddy, S., and Aggarwal, inhibitor
of
effect of curcumin,
muscle
NIH 3T3 cells. Carcinogenesis selective
C activity
of action J. Pharmacol.,
by 12-0-tetradecanoyl-1 (Lond.), 14: 857-861 , 1993.
kinase
1 . Folkman, J., and Shing, 10934, 1992.
Can-
17. Huang, M. T., Lou, V. A., Ma, W., Newark, H. L, Reuhl, K. A., and Conney, A. H. Inhibitory effect of dietary curcumin on forestomach, duodenal, and colon caranogenesis in mice. Cancer Res., 54: 5841-5847, 1994.
20. Liu, J. Y., Lin, S. J., and Lin, J. k. Inhibitory The opinions
A. H. Inhibitory
effect of curcumin, chlorgenic acid, caffeic acid, and ferulic acid on tumor
endothelial
cells
into capillary-like
structures
in vitro.
1989.
cells. J. Cell. Physiol, U. k. Cleavage
the head of bacteriophage
13:
196-20,
factor increases in microvascular
1992.
proteins during the assembly T4. Nature (Lond.), 227: 680-685, 1970. of structural
of
